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Sample records for nonlinear perforate behavior

  1. Finite element model calibration of a nonlinear perforated plate

    Science.gov (United States)

    Ehrhardt, David A.; Allen, Matthew S.; Beberniss, Timothy J.; Neild, Simon A.

    2017-03-01

    This paper presents a case study in which the finite element model for a curved circular plate is calibrated to reproduce both the linear and nonlinear dynamic response measured from two nominally identical samples. The linear dynamic response is described with the linear natural frequencies and mode shapes identified with a roving hammer test. Due to the uncertainty in the stiffness characteristics from the manufactured perforations, the linear natural frequencies are used to update the effective modulus of elasticity of the full order finite element model (FEM). The nonlinear dynamic response is described with nonlinear normal modes (NNMs) measured using force appropriation and high speed 3D digital image correlation (3D-DIC). The measured NNMs are used to update the boundary conditions of the full order FEM through comparison with NNMs calculated from a nonlinear reduced order model (NLROM). This comparison revealed that the nonlinear behavior could not be captured without accounting for the small curvature of the plate from manufacturing as confirmed in literature. So, 3D-DIC was also used to identify the initial static curvature of each plate and the resulting curvature was included in the full order FEM. The updated models are then used to understand how the stress distribution changes at large response amplitudes providing a possible explanation of failures observed during testing.

  2. Nonlinearities in Behavioral Macroeconomics.

    Science.gov (United States)

    Gomes, Orlando

    2017-07-01

    This article undertakes a journey across the literature on behavioral macroeconomics, with attention concentrated on the nonlinearities that the behavioral approach typically suggests or implies. The emphasis is placed on thinking the macro economy as a living organism, composed of many interacting parts, each one having a will of its own, which is in sharp contrast with the mechanism of the orthodox view (well represented by the neoclassical or new Keynesian dynamic stochastic general equilibrium - DSGE - model). The paper advocates that a thorough understanding of individual behavior in collective contexts is the only possible avenue to further explore macroeconomic phenomena and the often observed 'anomalies' that the benchmark DSGE macro framework is unable to explain or justify. After a reflection on the role of behavioral traits as a fundamental component of a new way of thinking the economy, the article proceeds with a debate on some of the most relevant frameworks in the literature that somehow link macro behavior and nonlinearities; covered subjects include macro models with disequilibrium rules, agent-based models that highlight interaction and complexity, evolutionary switching frameworks, and inattention based decision problems. These subjects have, as a fundamental point in common, the use of behavioral elements to transform existing interpretations of the economic reality, making it more evident how irregular fluctuations emerge and unfold on the aggregate.

  3. Second-Order Nonlinearity in Triangular Lattice Perforated Gold Film due to Surface Plasmas Resonance

    Directory of Open Access Journals (Sweden)

    Renlong Zhou

    2014-01-01

    Full Text Available We have studied the excitation second-order nonlinearity through a triangular lattice perforated gold film instead of square lattice in many papers. Under the excitation of surface plasmas resonance effect, the second order nonlinearity exists in the noncentrosymmetric split-ring resonators arrays. Reflection of fundamental frequency wave through a triangular lattice perforated gold film is obtained. We also described the second harmonic conversion efficiencies in the second order nonlinear optical process with the spectra. Moreover, the electric field distributions of fundamental frequency above the gold film region are calculated. The light propagation through the holes results in the enhancement of the second order nonlinearity including second harmonic generation as well as the sum (difference frequency generation.

  4. Flow Behavior in Z-Path Fluidized-Moving Bed with Inclined Perforated Plate

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The flow behaviors in a gas-solid contactor with inclined perforated plates that form a zigzag path were experimentally studied. In this contactor solid particles slide down along the inclined perforated plates by the upflowing gas. This structure, called as "z-path-moving bed", has some of the advantages of both moving and fluidized beds. The discharge rate of solid particles, inclination angle of the perforated plate, aperture ratio of the perforated plate, size of particles and gas velocity were chosen as parameters for experimental conditions. The stable operation conditions were certained for the particles and apparatus used. The pressure drop, bed height and residence time distribution of particles were measured versus gas velocity.

  5. Optimisation of micro-perforated cylindrical silencers in linear and nonlinear regimes

    Science.gov (United States)

    Bravo, Teresa; Maury, Cédric; Pinhède, Cédric

    2016-02-01

    This paper describes analytical and experimental studies conducted to understand the potential of lightweight non-fibrous alternatives to dissipative mufflers for in-duct noise control problems, especially under high sound pressure levels (SPLs) and in the low frequency domain. The cost-efficient multi-modal propagation method has been extended to predict nonlinear effects in the dissipation and the transmission loss (TL) of micro-perforated cylindrical liners with sub-millimetric holes diameter. A validation experiment was performed in a standing wave tube to measure the power dissipated and transmitted by a nonlocally reacting liner under moderate and high SPLs. Although nonlinear effects significantly reduce the dissipation and TL around the liner maximum damping frequency, these power quantities may be enhanced below the half-bandwidth resonance. An optimal value of the in-hole peak particle velocity has been found that maximizes the TL of locally reacting liners at low frequencies. Optimisation studies based on dissipation or TL maximization showed the sensitivity of the liner constituting parameters to variations in the design target range such as the center frequency, the levels of acoustic excitation and the nature of the surface impedance (locally or nonlocally reacting). An analysis is proposed of the deviation observed at low frequencies between the optimum impedance of the locally reacting liner under moderate SPLs and Cremer's optimum impedances.

  6. Buckling Behavior of Cold-Formed Studs with Thermal Perforations

    Directory of Open Access Journals (Sweden)

    Garifullin Marsel

    2016-01-01

    Full Text Available Studies have shown that the optimal structural scheme for low-rise buildings that meets all regulatory requirements is a frame system. In this connection, thin-walled cold-formed steel (CFS profiles seem to be the best material for constructing light steel framed (LSF walls. The framework of LSF walls is usually constructed from CFS C-shaped profiles. To increase the thermal effectiveness of a wall, CFS profiles usually have thermal perforations and thus are called thermoprofiles. However, these openings have a negative impact on bearing capacity of profiles and require accurate evaluation. In this article a relatively new reticular-stretched thermoprofile with diamond-shaped openings is considered. The article deals with the buckling analysis of perforated CFS C-sections subjected to compression.

  7. Nonlinear behavior of Helmholtz resonators

    Science.gov (United States)

    Hersh, A. S.

    1990-10-01

    A semi-empirical fluid mechanical model has been derived to predict the nonlinear acoustic behavior of thin-walled, single-orifice Helmholtz resonators. The model assumed that the sound particle velocity field approaches the resonator in a spherically symmetric manner. The incident and cavity sound pressure fields are connected in terms of an orifice discharge coefficient and an end correction parameter whose values are determined empirically. The accuracy of the model was verified by comparing predicted with measured impedance over a wide range of sound amplitudes and frequencies for two different resonator geometries and with measurements conducted by Ingard and Ising.

  8. Nonlinear dynamics in human behavior

    Energy Technology Data Exchange (ETDEWEB)

    Huys, Raoul [Centre National de la Recherche Scientifique (CNRS), 13 - Marseille (France); Marseille Univ. (France). Movement Science Inst.; Jirsa, Viktor K. (eds.) [Centre National de la Recherche Scientifique (CNRS), 13 - Marseille (France); Marseille Univ. (France). Movement Science Inst.; Florida Atlantic Univ., Boca Raton, FL (United States). Center for Complex Systems and Brain Sciences

    2010-07-01

    Humans engage in a seemingly endless variety of different behaviors, of which some are found across species, while others are conceived of as typically human. Most generally, behavior comes about through the interplay of various constraints - informational, mechanical, neural, metabolic, and so on - operating at multiple scales in space and time. Over the years, consensus has grown in the research community that, rather than investigating behavior only from bottom up, it may be also well understood in terms of concepts and laws on the phenomenological level. Such top down approach is rooted in theories of synergetics and self-organization using tools from nonlinear dynamics. The present compendium brings together scientists from all over the world that have contributed to the development of their respective fields departing from this background. It provides an introduction to deterministic as well as stochastic dynamical systems and contains applications to motor control and coordination, visual perception and illusion, as well as auditory perception in the context of speech and music. (orig.)

  9. Nonlinear System Identification and Behavioral Modeling

    CERN Document Server

    Huq, Kazi Mohammed Saidul; Kabir, A F M Sultanul

    2010-01-01

    The problem of determining a mathematical model for an unknown system by observing its input-output data pair is generally referred to as system identification. A behavioral model reproduces the required behavior of the original analyzed system, such as there is a one-to-one correspondence between the behavior of the original system and the simulated system. This paper presents nonlinear system identification and behavioral modeling using a work assignment.

  10. Numerical Simulations for Nonlinear Waves Interaction with Multiple Perforated Quasi-Ellipse Caissons

    Directory of Open Access Journals (Sweden)

    Xiaozhong Ren

    2015-01-01

    Full Text Available A three-dimensional numerical flume is developed to study cnoidal wave interaction with multiple arranged perforated quasi-ellipse caissons. The continuity equation and the Navier-Stokes equations are used as the governing equation, and the VOF method is adopted to capture the free surface elevation. The equations are discretized on staggered cells and then solved using a finite difference method. The generation and propagation of cnoidal waves in the numerical flume are tested first. And the ability of the present model to simulate interactions between waves and structures is verified by known experimental results. Then cnoidal waves with varying incident wave height and period are generated and interact with multiple quasi-ellipse caissons with and without perforation. It is found that the perforation plays an effective role in reducing wave runup/rundown and wave forces on the caissons. The wave forces on caissons reduce with the decreasing incident wave period. The influence of the transverse distance of multiple caissons on wave forces is also investigated. A closer transverse distance between caissons can produce larger wave forces. But when relative adjacent distance L/D (L is the transverse distance and D is the width of the quasi-ellipse caisson is larger than 3, the effect of adjacent distance is limited.

  11. Geometrically nonlinear behavior of piezoelectric laminated plates

    Science.gov (United States)

    Rabinovitch, Oded

    2005-08-01

    The geometrically nonlinear behavior of piezo-laminated plates actuated with isotropic or anisotropic piezoelectric layers is analytically investigated. The analytical model is derived using the variational principle of virtual work along with the lamination and plate theories, the von Karman large displacement and moderate rotation kinematic relations, and the anisotropic piezoelectric constitutive laws. A solution strategy that combines the approach of the method of lines, the advantages of the finite element concept, and the variational formulation is developed. This approach yields a set of nonlinear ordinary differential equations with nonlinear boundary conditions, which are solved using the multiple-shooting method. Convergence and verification of the model are examined through comparison with linear and nonlinear results of other approximation methods. The nonlinear response of two active plate structures is investigated numerically. The first plate is actuated in bending using monolithic piezoceramic layers and the second one is actuated in twist using macro-fiber composites. The results quantitatively reveal the complicated in-plane stress state associated with the piezoelectric actuation and the geometrically nonlinear coupling of the in-plane and out-of-plane responses of the plate. The influence of the nonlinear effects ranges from significant stiffening in certain combinations of electrical loads and boundary conditions to amplifications of the induced deflections in others. The paper closes with a summary and conclusions.

  12. Nonlinear behavior of the tarka flute's distinctive sounds

    Science.gov (United States)

    Gérard, Arnaud; Yapu-Quispe, Luis; Sakuma, Sachiko; Ghezzi, Flavio; Ramírez-Ávila, Gonzalo Marcelo

    2016-09-01

    The Andean tarka flute generates multiphonic sounds. Using spectral techniques, we verify two distinctive musical behaviors and the nonlinear nature of the tarka. Through nonlinear time series analysis, we determine chaotic and hyperchaotic behavior. Experimentally, we observe that by increasing the blow pressure on different fingerings, peculiar changes from linear to nonlinear patterns are produced, leading ultimately to quenching.

  13. Complex behavior in chains of nonlinear oscillators

    Science.gov (United States)

    Alonso, Leandro M.

    2017-06-01

    This article outlines sufficient conditions under which a one-dimensional chain of identical nonlinear oscillators can display complex spatio-temporal behavior. The units are described by phase equations and consist of excitable oscillators. The interactions are local and the network is poised to a critical state by balancing excitation and inhibition locally. The results presented here suggest that in networks composed of many oscillatory units with local interactions, excitability together with balanced interactions is sufficient to give rise to complex emergent features. For values of the parameters where complex behavior occurs, the system also displays a high-dimensional bifurcation where an exponentially large number of equilibria are borne in pairs out of multiple saddle-node bifurcations.

  14. Modeling of unusual nonlinear behaviors in superconducting microstrip transmission lines

    Energy Technology Data Exchange (ETDEWEB)

    Javadzadeh, S. Mohammad Hassan, E-mail: smh_javadzadeh@ee.sharif.edu [School of Electrical Engineering, Sharif University of Technology, P.O. Box 11365-9363, Tehran (Iran, Islamic Republic of); Farzaneh, Forouhar; Fardmanesh, Mehdi [School of Electrical Engineering, Sharif University of Technology, P.O. Box 11365-9363, Tehran (Iran, Islamic Republic of)

    2013-03-15

    Highlights: ► Avoiding of considering just quadratic or modulus nonlinearity. ► Proposing a nonlinear model to predict unusual nonlinear behaviors at low temperatures. ► Description of temperature dependency of nonlinear behaviors in superconducting lines. ► Analytical formulation for each parameter in our proposed model. ► Obtaining very good results which shows this model can predict unusual nonlinear behavior. -- Abstract: There are unusual nonlinear behaviors in superconducting materials, especially at low temperatures. This paper describes the procedure to reliably predict this nonlinearity in superconducting microstrip transmission lines (SMTLs). An accurate nonlinear distributed circuit model, based on simultaneously considering of both quadratic and modulus nonlinearity dependences, is proposed. All parameters of the equivalent circuit can be calculated analytically using proposed closed-form expressions. A numerical method based on Harmonic Balance approach is used to predict nonlinear phenomena like intermodulation distortions and third harmonic generations. Nonlinear analyses of the SMTLs at the different temperatures and the input powers have been presented. This proposed model can describe the unusual behaviors of the nonlinearity at low temperatures, which are frequently observed in the SMTLs.

  15. Measuring nonlinear behavior in time series data

    Science.gov (United States)

    Wai, Phoong Seuk; Ismail, Mohd Tahir

    2014-12-01

    Stationary Test is an important test in detect the time series behavior since financial and economic data series always have missing data, structural change as well as jumps or breaks in the data set. Moreover, stationary test is able to transform the nonlinear time series variable to become stationary by taking difference-stationary process or trend-stationary process. Two different types of hypothesis testing of stationary tests that are Augmented Dickey-Fuller (ADF) test and Kwiatkowski-Philips-Schmidt-Shin (KPSS) test are examine in this paper to describe the properties of the time series variables in financial model. Besides, Least Square method is used in Augmented Dickey-Fuller test to detect the changes of the series and Lagrange multiplier is used in Kwiatkowski-Philips-Schmidt-Shin test to examine the properties of oil price, gold price and Malaysia stock market. Moreover, Quandt-Andrews, Bai-Perron and Chow tests are also use to detect the existence of break in the data series. The monthly index data are ranging from December 1989 until May 2012. Result is shown that these three series exhibit nonlinear properties but are able to transform to stationary series after taking first difference process.

  16. Analysis of nonlinear behavior of loudspeakers using the instantaneous frequency

    DEFF Research Database (Denmark)

    Huang, Hai; Jacobsen, Finn

    2003-01-01

    It is well know that the weakest link in a sound reproduction chain is the loudspeaker. The most significant effect on the sound quality is nonlinear distortion of loudspeakers. Many methods are applied to analyze the nonlinear distortion of loudspeakers. Almost all of the methods are based...... on the Fourier transform. In this work, a new method using the instantaneous frequency is introduced for describing and characterizing loudspeaker nonlinearities. First, numerical integration is applied to simulate the nonlinearities of loudspeakers caused by two nonlinear parameters, force factor and stiffness......, separately. Then, a practical loudspeaker is used in an experiment and its nonlinear characteristics are analyzed with the instantaneous frequency. The results provide a clear physical interpretation of the nonlinearities of loudspeakers and will be useful for understanding the nonlinear behavior...

  17. A nonlinear Schroedinger wave equation with linear quantum behavior

    Energy Technology Data Exchange (ETDEWEB)

    Richardson, Chris D.; Schlagheck, Peter; Martin, John; Vandewalle, Nicolas; Bastin, Thierry [Departement de Physique, University of Liege, 4000 Liege (Belgium)

    2014-07-01

    We show that a nonlinear Schroedinger wave equation can reproduce all the features of linear quantum mechanics. This nonlinear wave equation is obtained by exploring, in a uniform language, the transition from fully classical theory governed by a nonlinear classical wave equation to quantum theory. The classical wave equation includes a nonlinear classicality enforcing potential which when eliminated transforms the wave equation into the linear Schroedinger equation. We show that it is not necessary to completely cancel this nonlinearity to recover the linear behavior of quantum mechanics. Scaling the classicality enforcing potential is sufficient to have quantum-like features appear and is equivalent to scaling Planck's constant.

  18. Nonlinear constitutive behavior of ferroelectric materials

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The ferroelectric specimen is considered as an aggregation of many randomly oriented domains. According to this mechanism,a multi-domain mechanical model is developed in this paper. Each domain is represented by one element. The applied stress and electric field are taken to be the stress and electric field in the formula of the driving force of domain switching for each element in the specimen. It means that the macroscopic switching criterion is used for calculating the volume fraction of domain switching for each element. By using the hardening relation between the driving force of domain switching and the volume fraction of domain switching calibrated,the volume fraction of domain switching for each element is calculated. Substituting the stress and electric field and the volume fraction of domain switching into the constitutive equation of ferroelectric material,one can easily get the strain and electric displacement for each element. The macroscopic behavior of the ferroelectric specimen is then directly calculated by volume averaging. Mean-while,the nonlinear finite element analysis for the ferroelectric specimen is carried out. In the finite element simulation,the volume fraction of domain switching for each element is calculated by using the same method mentioned above. The in-teraction between different elements is taken into account in the finite element simulation and the local stress and electric field for each element is obtained. The macroscopic behavior of the specimen is then calculated by volume averaging. The computation results involve the electric butterfly shaped curves of axial strain versus the axial electric field and the hysteresis loops of electric displacement versus the electric field for ferroelectric specimens under the uniaxial coupled stress and electric field loading. The present theoretical prediction agrees reasonably with the experimental results.

  19. Chaotic behavior in nonlinear polarization dynamics

    Energy Technology Data Exchange (ETDEWEB)

    David, D.; Holm, D.D.; Tratnik, M.V. (Los Alamos National Lab., NM (USA))

    1989-01-01

    We analyze the problem of two counterpropagating optical laser beams in a slightly nonlinear medium from the point of view of Hamiltonian systems; the one-beam subproblem is also investigated as a special case. We are interested in these systems as integrable dynamical systems which undergo chaotic behavior under various types of perturbations. The phase space for the two-beam problem is C{sup 2} {times} C{sup 2} when we restricted the the regime of travelling-wave solutions. We use the method of reduction for Hamiltonian systems invariant under one-parameter symmetry groups to demonstrate that the phase space reduces to the two-sphere S{sup 2} and is therefore completely integrable. The phase portraits of the system are classified and we also determine the bifurcations that modify these portraits; some new degenerate bifurcations are presented in this context. Finally, we introduce various physically relevant perturbations and use the Melnikov method to prove that horseshoe chaos and Arnold diffusion occur as consequences of these perturbations. 10 refs., 7 figs., 1 tab.

  20. Nonlinear electronic transport behavior in Indium Nitride

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Cloves G., E-mail: cloves@pucgoias.edu.br [Departamento de Fisica, Pontificia Universidade Catolica de Goias, CP 86, 74605-010 Goiania, Goias (Brazil)

    2012-11-15

    A theoretical study on the nonlinear transport of electrons and of the nonequilibrium temperature in n-doped Indium Nitride under influence of moderate to high electric fields (in this nonlinear domain) is presented. It is based on a nonlinear quantum kinetic theory which provides a description of the dissipative phenomena developing in the system. The electric current and the mobility in the steady state are obtained, and their dependence on the electric field strength and on the concentration (that is, a mobility dependent nonlinearly on field and concentration) is obtained and analyzed. -- Highlights: Black-Right-Pointing-Pointer We have reported on the topic of nonlinear transport (electron mobility) in n-doped InN. Black-Right-Pointing-Pointer The results evidence the presence of two distinctive regimes. Black-Right-Pointing-Pointer The dependence of the mobility on the electric field is manifested through of the relaxation times.

  1. Nonlinear Finite Strain Consolidation Analysis with Secondary Consolidation Behavior

    Directory of Open Access Journals (Sweden)

    Jieqing Huang

    2014-01-01

    Full Text Available This paper aims to analyze nonlinear finite strain consolidation with secondary consolidation behavior. On the basis of some assumptions about the secondary consolidation behavior, the continuity equation of pore water in Gibson’s consolidation theory is modified. Taking the nonlinear compressibility and nonlinear permeability of soils into consideration, the governing equation for finite strain consolidation analysis is derived. Based on the experimental data of Hangzhou soft clay samples, the new governing equation is solved with the finite element method. Afterwards, the calculation results of this new method and other two methods are compared. It can be found that Gibson’s method may underestimate the excess pore water pressure during primary consolidation. The new method which takes the secondary consolidation behavior, the nonlinear compressibility, and nonlinear permeability of soils into consideration can precisely estimate the settlement rate and the final settlement of Hangzhou soft clay sample.

  2. Theory of nonlinear elastic behavior in rock

    Energy Technology Data Exchange (ETDEWEB)

    McCall, K.R.

    1993-04-01

    We study plane wave propagation in an isotropic, homogeneous solid with cubic and quartic anharmonicity. Attenuation is introduced through use of a retarded displacement response. We develop a Green function technique to exhibit the solution for the displacement field as a systematic hierarchy in the nonlinear parameters. This solution is applied to three problems: propagation from monochromatic and broadband sources, and the shape of nonlinear stress curves.

  3. Theory of nonlinear elastic behavior in rock

    Energy Technology Data Exchange (ETDEWEB)

    McCall, K.R.

    1993-01-01

    We study plane wave propagation in an isotropic, homogeneous solid with cubic and quartic anharmonicity. Attenuation is introduced through use of a retarded displacement response. We develop a Green function technique to exhibit the solution for the displacement field as a systematic hierarchy in the nonlinear parameters. This solution is applied to three problems: propagation from monochromatic and broadband sources, and the shape of nonlinear stress curves.

  4. Perforating pilomatricoma.

    Science.gov (United States)

    Zulaica, A; Peteiro, C; Quintas, C; Pereiro, M; Toribio, J

    1988-12-01

    A case of perforating pilomatricoma is described. A few published cases have shared the following features: rapid development, reddish exophytic clinical appearance with surface alterations suggestive of perforation, relatively shallow location making contact with the epidermis, and the occurrence of transepithelial elimination phenomena.

  5. Acoustic Treatment Design Scaling Methods. Volume 4; Numerical Simulation of the Nonlinear Acoustic Impedance of a Perforated Plate Single-Degree-of-Freedom Resonator Using a Time-Domain Finite Difference Method

    Science.gov (United States)

    Kraft, R. E.

    1999-01-01

    Single-degree-of-freedom resonators consisting of honeycomb cells covered by perforated facesheets are widely used as acoustic noise suppression liners in aircraft engine ducts. The acoustic resistance and mass reactance of such liners are known to vary with the intensity of the sound incident upon the panel. Since the pressure drop across a perforated liner facesheet increases quadratically with the flow velocity through the facesheet, this is known as the nonlinear resistance effect. In the past, two different empirical frequency domain models have been used to predict the Sound Pressure Level effect of the incident wave on the perforated liner impedance, one that uses the incident particle velocity in isolated narrowbands, and one that models the particle velocity as the overall velocity. In the absence of grazing flow, neither frequency domain model is entirely accurate in predicting the nonlinear effect that is measured for typical perforated sheets. The time domain model is developed in an attempt to understand and improve the model for the effect of spectral shape and amplitude of multi-frequency incident sound pressure on the liner impedance. A computer code for the time-domain finite difference model is developed and predictions using the models are compared to current frequency-domain models.

  6. High power laser perforating tools and systems

    Science.gov (United States)

    Zediker, Mark S; Rinzler, Charles C; Faircloth, Brian O; Koblick, Yeshaya; Moxley, Joel F

    2014-04-22

    ystems devices and methods for the transmission of 1 kW or more of laser energy deep into the earth and for the suppression of associated nonlinear phenomena. Systems, devices and methods for the laser perforation of a borehole in the earth. These systems can deliver high power laser energy down a deep borehole, while maintaining the high power to perforate such boreholes.

  7. Epileptic EEG: a comprehensive study of nonlinear behavior.

    Science.gov (United States)

    Daneshyari, Moayed; Kamkar, L Lily; Daneshyari, Matin

    2010-01-01

    In this study, the nonlinear properties of the electroencephalograph (EEG) signals are investigated by comparing two sets of EEG, one set for epileptic and another set for healthy brain activities. Adopting measures of nonlinear theory such as Lyapunov exponent, correlation dimension, Hurst exponent, fractal dimension, and Kolmogorov entropy, the chaotic behavior of these two sets is quantitatively computed. The statistics for the two groups of all measures demonstrate the differences between the normal healthy group and epileptic one. The statistical results along with phase-space diagram verify that brain under epileptic seizures possess limited trajectory in the state space than in healthy normal state, consequently behaves less chaotically compared to normal condition.

  8. Nonlinear electro-mechanobiological behavior of cell membrane during electroporation

    KAUST Repository

    Deng, Peigang

    2012-01-01

    A nonlinear electroporation (EP) model is proposed to study the electro-mechanobiological behavior of cell membrane during EP, by taking the nonlinear large deformation of the membrane into account. The proposed model predicts the critical transmembrane potential and the activation energy for EP, the equilibrium pore size, and the resealing process of the pore. Single-cell EP experiments using a micro EP chip were conducted on chicken red blood cells at different temperatures to determine the activation energy and the critical transmembrane potential for EP. The experimental results are in good agreement with the theoretical predictions. © 2012 American Institute of Physics.

  9. Mathematical Systems Theory : from Behaviors to Nonlinear Control

    CERN Document Server

    Julius, A; Pasumarthy, Ramkrishna; Rapisarda, Paolo; Scherpen, Jacquelien

    2015-01-01

    This treatment of modern topics related to mathematical systems theory forms the proceedings of a workshop, Mathematical Systems Theory: From Behaviors to Nonlinear Control, held at the University of Groningen in July 2015. The workshop celebrated the work of Professors Arjan van der Schaft and Harry Trentelman, honouring their 60th Birthdays. The first volume of this two-volume work covers a variety of topics related to nonlinear and hybrid control systems. After giving a detailed account of the state of the art in the related topic, each chapter presents new results and discusses new directions. As such, this volume provides a broad picture of the theory of nonlinear and hybrid control systems for scientists and engineers with an interest in the interdisciplinary field of systems and control theory. The reader will benefit from the expert participants’ ideas on exciting new approaches to control and system theory and their predictions of future directions for the subject that were discussed at the worksho...

  10. Nonlinear vibration behaviors of casing pipe in the deep water

    Science.gov (United States)

    Tang, You-Gang; Zhang, Su-Xia; Yi, Cong

    2006-10-01

    The vortex-induced nonlinear vibration of casing pipes in the deep water was investigated considering the loads of current and combined wave-current. The vortex-induced vibration equation of a casing pipe was set up with considering the beam mode and Morison's nonlinear fluid loads as well as the vortex-excited loads. The approach of calculating vortex-excited nonlinear vibration by Galerkin's method was proposed. The natural vibration frequencies and modes were obtained, and the response including primary resonance induced by current and the composite resonance under combined wave-current for the 170 m long casing pipe in the 160 m depth of water were investigated. The results show that the dynamics response of casing pipe obviously increases, and the complicated response behaviors of casing pipe are described under combined wave-current.

  11. Analysis of nonlinear elastic behavior in miniature pneumatic artificial muscles

    Science.gov (United States)

    Hocking, Erica G.; Wereley, Norman M.

    2013-01-01

    Pneumatic artificial muscles (PAMs) are well known for their excellent actuator characteristics, including high specific work, specific power, and power density. Recent research has focused on miniaturizing this pneumatic actuator technology in order to develop PAMs for use in small-scale mechanical systems, such as those found in robotic or aerospace applications. The first step in implementing these miniature PAMs was to design and characterize the actuator. To that end, this study presents the manufacturing process, experimental characterization, and analytical modeling of PAMs with millimeter-scale diameters. A fabrication method was developed to consistently produce low-cost, high performance, miniature PAMs using commercially available materials. The quasi-static behavior of these PAMs was determined through experimentation on a single actuator with an active length of 39.16 mm (1.54 in) and a diameter of 4.13 mm (0.1625 in). Testing revealed the PAM’s full evolution of force with displacement for operating pressures ranging from 207 to 552 kPa (30-80 psi in 10 psi increments), as well as the blocked force and free contraction at each pressure. Three key nonlinear phenomena were observed: nonlinear PAM stiffness, hysteresis of the force versus displacement response for a given pressure, and a pressure deadband. To address the analysis of the nonlinear response of these miniature PAMs, a nonlinear stress versus strain model, a hysteresis model, and a pressure bias are introduced into a previously developed force balance analysis. Parameters of these nonlinear model refinements are identified from the measured force versus displacement data. This improved nonlinear force balance model is shown to capture the full actuation behavior of the miniature PAMs at each operating pressure and reconstruct miniature PAM response with much more accuracy than previously possible.

  12. Non-linear Behavior of Curved Sandwich Panels

    DEFF Research Database (Denmark)

    Berggreen, Carl Christian; Jolma, P.; Karjalainen, J. P.;

    2003-01-01

    In this paper the non-linear behavior of curved sandwich panels is investigated both numerically and experimentally. Focus is on various aspects of finite element modeling and calculation procedures. A simply supported, singly curved, CFRP/PVC sandwich panel is analyzed under uniform pressure load...... and results are compared to test data. A novel test arrangement utilizing a water filled cushion to create the uniform pressure load on curved panel specimen is used to obtain the experimental data. The panel is modeled with three different commercial finite element codes. Two implicit and one explicit code...... are used with various element types, modeling approaches and material models. The results show that the theoretical and experimental methods generally show fair agreement in panel non-linear behavior before collapse. It is also shown that special attention to detail has to be taken, because the predicted...

  13. The thermomechanics of nonlinear irreversible behaviors an introduction

    CERN Document Server

    Maugin, Gérard A

    1999-01-01

    In this invaluable book, macroscopic irreversible thermodynamics is presented in its realm and its splendor by appealing to the notion of internal variables of state. This applies to both fluids and solids with or without microstructures of mechanical or electromagnetic origin. This unmatched richness of essentially nonlinear behaviors is the result of the use of modern mathematical techniques such as convex analysis in a clear-cut framework which allows one to put under the umbrella of "irreversible thermodynamics" behaviors which until now have been commonly considered either not easily cove

  14. Behavioral deficits in sepsis-surviving rats induced by cecal ligation and perforation

    Directory of Open Access Journals (Sweden)

    T. Barichello

    2007-06-01

    Full Text Available Sepsis and its complications are the leading causes of mortality in intensive care units, accounting for 10-50% of deaths. Intensive care unit survivors present long-term cognitive impairment, including alterations in memory, attention, concentration, and/or global loss of cognitive function. In the present study, we investigated behavioral alterations in sepsis-surviving rats. One hundred and ten male Wistar rats (3-4 months, 250-300 g were submitted to cecal ligation and puncture (CLP, and 44 were submitted to sham operation. Forty-four rats (40% survived after CLP, and all sham-operated animals survived and were used as control. Twenty animals of each group were used in the object recognition task (10 in short-term memory and 10 in long-term memory, 12 in the plus-maze test and 12 in the forced swimming test. Ten days after surgery, the animals were submitted individually to an object recognition task, plus-maze and forced swimming tests. A significant impairment of short- and long-term recognition memory was observed in the sepsis group (recognition index 0.75 vs 0.55 and 0.74 vs 0.51 for short- and long-term memory, respectively (P < 0.05. In the elevated plus-maze test no difference was observed between groups in any of the parameters assessed. In addition, sepsis survivors presented an increase in immobility time in the forced swimming test (180 vs 233 s, P < 0.05, suggesting the presence of depressive-like symptoms in these animals after recovery from sepsis. The present results demonstrated that rats surviving exposure to CLP, a classical sepsis model, presented recognition memory impairment and depressive-like symptoms but not anxiety-like behavior.

  15. Nonlinear dynamic behaviors of a floating structure in focused waves

    Science.gov (United States)

    Cao, Fei-feng; Zhao, Xi-zeng

    2015-12-01

    Floating structures are commonly seen in coastal and offshore engineering. They are often subjected to extreme waves and, therefore, their nonlinear dynamic behaviors are of great concern. In this paper, an in-house CFD code is developed to investigate the accurate prediction of nonlinear dynamic behaviors of a two-dimensional (2-D) box-shaped floating structure in focused waves. Computations are performed by an enhanced Constrained Interpolation Profile (CIP)-based Cartesian grid model, in which a more accurate VOF (Volume of Fluid) method, the THINC/SW scheme (THINC: tangent of hyperbola for interface capturing; SW: Slope Weighting), is used for interface capturing. A focusing wave theory is used for the focused wave generation. The wave component of constant steepness is chosen. Comparisons between predictions and physical measurements show good agreement including body motions and free surface profiles. Although the overall agreement is good, some discrepancies are observed for impact pressure on the superstructure due to water on deck. The effect of grid resolution on the results is checked. With a fine grid, no obvious improvement is seen in the global body motions and impact pressures due to water on deck. It is concluded that highly nonlinear phenomena, such as distorted free surface, large-amplitude body motions, and violent impact flow, have been predicted successfully.

  16. Nonlinear behaviors of parity-time-symmetric lasers

    CERN Document Server

    Yang, Jianke

    2016-01-01

    We propose a time-dependent partial differential equation model to investigate the dynamical behavior of the parity-time (PT) symmetric laser during the nonlinear stage of its operation. This model incorporates physical effects such as the refractive index distribution, dispersion, material loss, nonlinear gain saturation and self-phase modulation. We show that when the loss is weak, multiple stable steady states and time-periodic states of light exist above the lasing threshold, rendering the laser multi-mode. However, when the loss is strong, only a single stable steady state of broken PT symmetry exists for a wide range of the gain amplitude, rendering the laser single-mode. These results reveal the important role the loss plays in maintaining the single-mode operation of PT lasers.

  17. Distinct behavioral phenotypes in novel "fast" kindling-susceptible and "slow" kindling-resistant rat strains selected by stimulation of the hippocampal perforant path.

    Science.gov (United States)

    Langberg, Tomer; Dashek, Ryan; Mulvey, Bernard; Miller, Kimberly A; Osting, Susan; Stafstrom, Carl E; Sutula, Thomas P

    2016-01-01

    Kindling is a phenomenon of activity-dependent neural circuit plasticity induced by repeated seizures that results in progressive permanent increases in susceptibility to epilepsy. As the permanent structural and functional modifications induced by kindling include a diverse range of molecular, cellular, and functional alterations in neural circuits, it is of interest to determine if genetic background associated with seizure-induced plasticity might also influence plasticity in neural circuitry underlying other behaviors. Outbred Sprague-Dawley (SD) rats were selected and bred for ~15 generations for "fast' or "slow" rates of kindling development in response to stimulation of the perforant path input to the hippocampus. After 7-8 generations of selection and breeding, consistent phenotypes of "fast" and "slow" kindling rates were observed. By the 15th generation "fast" kindling rats referred to as Perforant Path Kindling Susceptible (PPKS) rats demonstrated a kindling rate of 10.7 ± 1.1 afterdischarges (ADs) to the milestone of the first secondary generalized (Class V) seizure, which differed significantly from "slow" kindling Perforant Path Kindling Resistant (PPKR) rats requiring 25.5 ± 2.0 ADs, and outbred SD rats requiring 16.8 ± 2.5 ADs (pkindling) strain with increased susceptibility to seizure-induced plasticity demonstrated statistically significant increases in motor exploratory activity in the open field test and reduced spatial learning the Morris water maze, but demonstrated normal fear conditioned learning comparable to outbred SD rats and the "slow" kindling-resistant PPKR strain. These results confirm that selection and breeding on the basis of responses to repeated pathway activation by stimulation can produce enduring modification of genetic background influencing behavior. These observations also suggest that genetic background underlying susceptibility or resistance to seizure-induced plasticity in hippocampal circuitry also differentially

  18. Nonlinear behavior for nanoscale electrostatic actuators with Casimir force

    Energy Technology Data Exchange (ETDEWEB)

    Lin Wenhui [College of Science, China Agricultural University, Beijing 100083 (China); Zhao Yapu [State Key Laboratory of Nonlinear Mechanics (LNM), Institute of Mechanics, Chinese Academy of Sciences, Beijing 100080 (China)]. E-mail: yzhao@lnm.imech.ac.cn

    2005-03-01

    The influence of Casimir force on the nonlinear behavior of nanoscale electrostatic actuators is studied in this paper. A one degree of freedom mass-spring model is adopted and the bifurcation properties of the actuators are obtained. With the change of the geometrical dimensions, the number of equilibrium point varies from zero to two. Stability analysis shows that one equilibrium point is Hopf point and the other is unstable saddle point when there are two equilibrium points. We also obtain the phase portraits, in which the periodic orbits exist around the Hopf point, and a homoclinic orbit passes through the unstable saddle point.

  19. Nonlinear dynamic behaviors of ball bearing rotor system

    Institute of Scientific and Technical Information of China (English)

    WANG Li-qin; CUI Li; ZHENG De-zhi; GU Le

    2009-01-01

    Nonlinear forces and moments caused by ball bearing were calculated based on relationship of displacement and deflection and quasi-dynamic model of bearing. Five-DOF dynamic equations of rotor supported by ball bearings were estimated. The Newmark-β method and Newton-Laphson method were used to solve the equations. The dynamic characteristics of rotor system were studied through the time response, the phase portrait, the Poincar? maps and the bifurcation diagrams. The results show that the system goes through the quasiperiodic bifurcation route to chaos as rotate speed increases and there are several quasi-periodic regions and chaos regions. The amplitude decreases and the dynamic behaviors change as the axial load of ball bearing increases; the initial contact angle of ball bearing affects dynamic behaviors of the system obviously. The system can avoid non-periodic vibration by choosing structural parameters and operating parameters reasonably.

  20. Asymptotic behavior for a quadratic nonlinear Schrodinger equation

    Directory of Open Access Journals (Sweden)

    Pavel I. Naumkin

    2008-02-01

    Full Text Available We study the initial-value problem for the quadratic nonlinear Schrodinger equation $$displaylines{ iu_{t}+frac{1}{2}u_{xx}=partial _{x}overline{u}^{2},quad xin mathbb{R},; t>1, cr u(1,x=u_{1}(x,quad xin mathbb{R}. }$$ For small initial data $u_{1}in mathbf{H}^{2,2}$ we prove that there exists a unique global solution $uin mathbf{C}([1,infty ;mathbf{H}^{2,2}$ of this Cauchy problem. Moreover we show that the large time asymptotic behavior of the solution is defined in the region $|x|leq Csqrt{t}$ by the self-similar solution $frac{1}{sqrt{t}}MS(frac{x}{sqrt{t}}$ such that the total mass $$ frac{1}{sqrt{t}}int_{mathbb{R}}MS(frac{x}{sqrt{t}} dx=int_{mathbb{R}}u_{1}(xdx, $$ and in the far region $|x|>sqrt{t}$ the asymptotic behavior of solutions has rapidly oscillating structure similar to that of the cubic nonlinear Schrodinger equations.

  1. Strain Rate Effect on the Tensile Behavior of Fibers and Its Application to Ballistic Perforation of Multi-layered Fabrics

    Institute of Scientific and Technical Information of China (English)

    GU Bo-hong; PAN Xiong-qi

    2002-01-01

    Rate-dependent property of material is very important in analysis of ballistic impact. The tensile property of Twaron(R) filaments at strain rate range from 0.01/s to1 000/s was obtained by MTS materials testing and split Hopkinson tension bar. Rate sensitivity of Twaron(R) filaments is discussed. Application of high strain rate property to ballistic perforation of multi- layered fabrics conforms to the actual situation than that of quasi-static property. The revised analytical model can be used to calculate the process of ballistic penetration and perforation on soft armour, such as fabric target plate,at intuitive approach and simple algorithm with a little computer process time. Predictions of the residual velocities and energy absorbed by the multi- layered fabric show good agreement with experimental data.

  2. Spontaneous external gallbladder perforation

    Energy Technology Data Exchange (ETDEWEB)

    Noeldge, G.; Wimmer, B.; Kirchner, R.

    1981-04-01

    Spontaneous perforation of the gallbladder is one complication of cholelithiasis. There is a greater occurence of free perforation in the peritoneal cavity with bilary pertonitis, followed by the perforation into the stomach, small intestine and colon. A single case of the nowadays rare spontaneous perforation in and through the abdominal wall will be reported. Spontaneous gallbladder perforation appears nearly asymptomatic in its clinical course because of absent biliary peritonitis.

  3. Complex spatiotemporal behavior in a chain of one-way nonlinearly coupled elements

    DEFF Research Database (Denmark)

    Gaididei, Yuri Borisovich; Berkemer, Rainer; Gorria, C.;

    2011-01-01

    The dynamics of asymmetrically coupled nonlinear elements is considered. It is shown that there are two distinctive regimes of oscillatory behavior of one-way nonlinearly coupled elements depending on the relaxation time and the strength of the coupling. In the subcritical regime when...... nonlinear model....

  4. Linear and nonlinear behavior of human and artificial lip reeds

    Science.gov (United States)

    Campbell, Murray; Richards, Orlando

    2003-10-01

    In a musical instrument of the lip reed aerophone class, the flow of air from the player's lungs into the resonating air column is modulated by the periodic opening and closing of the pressure-controlled valve formed by the player's lips. The nature of the operation of this valve has been the subject of considerable study in recent years. Since the pressure-flow relationship is strongly nonlinear, the behavior of the coupled system of lips and air column can only be modeled using the methods of nonlinear dynamics. Extensive studies of artificial lip reeds, in which the lips are simulated by water-filled latex tubes, have shown them to be capable of reproducing musically important features of human playing, including the lipping of notes both below and above an acoustic resonance of the air column. Measurements of the linear response of artificial reeds have guided the development of more realistic models of the lip reed, while studies of both real and artificial lips using a high-speed digital camera have shed fresh light on the nature of the lip motion at the large amplitudes typical of loud playing. [Work supported by EPSRC.

  5. Nonlinear behavior of vibrating molecules on suspended graphene waveguides

    CERN Document Server

    Banerjee, Amrita

    2015-01-01

    Suspended graphene waveguides were deposited on micron-scale periodic metal (plasmonic) structures. Raman scattering of test molecules (B. Megaterium), deposited on the waveguides' surface, exhibited azimuthal cycles upon rotation: at these micron scales, spontaneous Raman ought to be independent of phase matching conditions. In addition, we observed angular-selective quadratic intensity dependence contrary to the typical linear behavior of spontaneous Raman. The effects were observed at very modest pump laser intensities (<10 MW/cm2 at the sample surface, oftenly used in Raman experiments). We attributed these observations to nonlinear coupling between the vibrating molecules and surface plasmon polariton (SPP) modes at the molecular vibration frequency. It was assessed that the polariton mode propagates through fairly long distances (over 100 microns).

  6. Dynamic behavior of a nonlinear rational difference equation and generalization

    Directory of Open Access Journals (Sweden)

    Shi Qihong

    2011-01-01

    Full Text Available Abstract This paper is concerned about the dynamic behavior for the following high order nonlinear difference equation x n = (x n-k + x n-m + x n-l /(x n-k x n-m + x n-m x n-l +1 with the initial data { x - l , x - l + 1 , … , x - 1 } ∈ ℝ + l and 1 ≤ k ≤ m ≤ l. The convergence of solution to this equation is investigated by introducing a new sequence, which extends and includes corresponding results obtained in the references (Li in J Math Anal Appl 312:103-111, 2005; Berenhaut et al. Appl. Math. Lett. 20:54-58, 2007; Papaschinopoulos and Schinas J Math Anal Appl 294:614-620, 2004 to a large extent. In addition, some propositions for generalized equations are reported.

  7. Asymptotic behavior of solutions to nonlinear parabolic equation with nonlinear boundary conditions

    Directory of Open Access Journals (Sweden)

    Diabate Nabongo

    2008-01-01

    Full Text Available We show that solutions of a nonlinear parabolic equation of second order with nonlinear boundary conditions approach zero as t approaches infinity. Also, under additional assumptions, the solutions behave as a function determined here.

  8. The Behavior of Filters and Smoothers for Strongly Nonlinear Dynamics

    Science.gov (United States)

    Zhu, Yanqiu; Cohn, Stephen E.; Todling, Ricardo

    1999-01-01

    The Kalman filter is the optimal filter in the presence of known Gaussian error statistics and linear dynamics. Filter extension to nonlinear dynamics is non trivial in the sense of appropriately representing high order moments of the statistics. Monte Carlo, ensemble-based, methods have been advocated as the methodology for representing high order moments without any questionable closure assumptions (e.g., Miller 1994). Investigation along these lines has been conducted for highly idealized dynamics such as the strongly nonlinear Lorenz (1963) model as well as more realistic models of the oceans (Evensen and van Leeuwen 1996) and atmosphere (Houtekamer and Mitchell 1998). A few relevant issues in this context are related to the necessary number of ensemble members to properly represent the error statistics and, the necessary modifications in the usual filter equations to allow for correct update of the ensemble members (Burgers 1998). The ensemble technique has also been applied to the problem of smoothing for which similar questions apply. Ensemble smoother examples, however, seem to quite puzzling in that results of state estimate are worse than for their filter analogue (Evensen 1997). In this study, we use concepts in probability theory to revisit the ensemble methodology for filtering and smoothing in data assimilation. We use Lorenz (1963) model to test and compare the behavior of a variety implementations of ensemble filters. We also implement ensemble smoothers that are able to perform better than their filter counterparts. A discussion of feasibility of these techniques to large data assimilation problems will be given at the time of the conference.

  9. Electrodynamic soil plate oscillator: Modeling nonlinear mesoscopic elastic behavior and hysteresis in nonlinear acoustic landmine detection

    Science.gov (United States)

    Korman, M. S.; Duong, D. V.; Kalsbeck, A. E.

    2015-10-01

    An apparatus (SPO), designed to study flexural vibrations of a soil loaded plate, consists of a thin circular elastic clamped plate (and cylindrical wall) supporting a vertical soil column. A small magnet attached to the center of the plate is driven by a rigid AC coil (located coaxially below the plate) to complete the electrodynamic soil plate oscillator SPO design. The frequency dependent mechanical impedance Zmech (force / particle velocity, at the plate's center) is inversely proportional to the electrical motional impedance Zmot. Measurements of Zmot are made using the complex output to input response of a Wheatstone bridge that has an identical coil element in one of its legs. Near resonance, measurements of Zmot (with no soil) before and after a slight point mass loading at the center help determine effective mass, spring, damping and coupling constant parameters of the system. "Tuning curve" behavior of real{ Zmot } and imaginary{ Zmot } at successively higher vibration amplitudes of dry sifted masonry sand are measured. They exhibit a decrease "softening" in resonance frequency along with a decrease in the quality Q factor. In soil surface vibration measurements a bilinear hysteresis model predicts the tuning curve shape for this nonlinear mesoscopic elastic SPO behavior - which also models the soil vibration over an actual plastic "inert" VS 1.6 buried landmine. Experiments are performed where a buried 1m cube concrete block supports a 12 inch deep by 30 inch by 30 inch concrete soil box for burying a VS 1.6 in dry sifted masonry sand for on-the-mine and off-the-mine soil vibration experiments. The backbone curve (a plot of the peak amplitude vs. corresponding resonant frequency from a family of tuning curves) exhibits mostly linear behavior for "on target" soil surface vibration measurements of the buried VS 1.6 or drum-like mine simulants for relatively low particle velocities of the soil. Backbone curves for "on target" measurements exhibit

  10. Reactive perforating collagenosis

    Directory of Open Access Journals (Sweden)

    Yadav Mukesh

    2009-01-01

    Full Text Available Reactive perforating collagenosis is a rare cutaneous disorder of unknown etiology. We hereby describe a case of acquired reactive perforating collagenosis in a patient of diabetes and chronic renal failure.

  11. Optimization of hardening/softening behavior of plane frame structures using nonlinear normal modes

    DEFF Research Database (Denmark)

    Dou, Suguang; Jensen, Jakob Søndergaard

    2016-01-01

    /softening behavior of nonlinear mechanical systems. The iterative optimization procedure consists of calculation of nonlinear normal modes, solving an adjoint equation system for sensitivity analysis and an update of design variables using a mathematical programming tool. We demonstrate the method with examples......Devices that exploit essential nonlinear behavior such as hardening/softening and inter-modal coupling effects are increasingly used in engineering and fundamental studies. Based on nonlinear normal modes, we present a gradient-based structural optimization method for tailoring the hardening...

  12. Nonlinear Behavior Of Saturated Porous Media Under External Impact

    Science.gov (United States)

    Perepechko, Y.

    2005-12-01

    This paper deals with nonlinear behavior of liquid saturated porous media in gravity filed under external impact. The continuum is assumed to be a two-velocity medium; it consists of a deformable porous matrix (with Maxwell's reology) and a Newtonian liquid that saturates this matrix. The energy dissipation in this model takes place due the interface friction between the solid matrix and saturating liquid, and also through relaxation of inelastic shear stress in the porous matrix. The elaborated nonisothermal mathematical model for this kind of medium is a thermodynamically consistent and closed model. Godunov's explicit difference scheme was used for computer simulation; the method implies numerical simulation for discontinuity decay in flux calculations. As an illustrative example, we consider the formation of dissipation structures in a plain layer of that medium after pulse or periodic impact on the background of liquid filtration through the porous matrix. At the process beginning, one can observe elastic behavior of the porous matrix. Deformation spreading through the saturated porous matrix occurs almost without distortions and produces a channel-shaped zone of stretching with a high porosity. Later on, dissipation processes and reology properties of porous medium causes the diffusion of this channel. We also observe a correlation between the liquid distribution (porosity for the solid matrix) and dilatancy fields; this allows us to restore the dilatancy field from the measured fluid saturation of the medium. This work was supported by the RFBR (Grant No. 04-05-64107), the Presidium of SB RAS (Grant 106), the President's Grants (NSh-2118.2003.5, NSh-1573.2003.5).

  13. In situ nonlinear elastic behavior of soil observed by DAET

    Energy Technology Data Exchange (ETDEWEB)

    Larmat, Carene [Los Alamos National Laboratory; Renaud, Guillaume [Eramus Medical Center, Rotterdam, The Netherlands; Rutledge, James T. [EES-17: GEOPHYSICS; Lee, Richard C. [Los Alamos National Laboratory; Guyer, Robert A. [Los Alamos National Laboratory; Johnson, Paul A. [Los Alamos National Laboratory

    2012-07-05

    The key to safe design of critical facilities (strong ground motion in low velocity materials such as soils). Current approaches are predictions from measurements of the elastic non-linear properties of boreholes samples. Need for in-situ, local and complete determination of non-linear properties of soil, rock in response to high-strain motion.

  14. Augmented twin-nonlinear two-box behavioral models for multicarrier LTE power amplifiers.

    Science.gov (United States)

    Hammi, Oualid

    2014-01-01

    A novel class of behavioral models is proposed for LTE-driven Doherty power amplifiers with strong memory effects. The proposed models, labeled augmented twin-nonlinear two-box models, are built by cascading a highly nonlinear memoryless function with a mildly nonlinear memory polynomial with cross terms. Experimental validation on gallium nitride based Doherty power amplifiers illustrates the accuracy enhancement and complexity reduction achieved by the proposed models. When strong memory effects are observed, the augmented twin-nonlinear two-box models can improve the normalized mean square error by up to 3 dB for the same number of coefficients when compared to state-of-the-art twin-nonlinear two-box models. Furthermore, the augmented twin-nonlinear two-box models lead to the same performance as previously reported twin-nonlinear two-box models while requiring up to 80% less coefficients.

  15. Augmented Twin-Nonlinear Two-Box Behavioral Models for Multicarrier LTE Power Amplifiers

    Directory of Open Access Journals (Sweden)

    Oualid Hammi

    2014-01-01

    Full Text Available A novel class of behavioral models is proposed for LTE-driven Doherty power amplifiers with strong memory effects. The proposed models, labeled augmented twin-nonlinear two-box models, are built by cascading a highly nonlinear memoryless function with a mildly nonlinear memory polynomial with cross terms. Experimental validation on gallium nitride based Doherty power amplifiers illustrates the accuracy enhancement and complexity reduction achieved by the proposed models. When strong memory effects are observed, the augmented twin-nonlinear two-box models can improve the normalized mean square error by up to 3 dB for the same number of coefficients when compared to state-of-the-art twin-nonlinear two-box models. Furthermore, the augmented twin-nonlinear two-box models lead to the same performance as previously reported twin-nonlinear two-box models while requiring up to 80% less coefficients.

  16. Nonlinear behavior of three-terminal graphene junctions at room temperature

    Science.gov (United States)

    Kim, Wonjae; Pasanen, Pirjo; Riikonen, Juha; Lipsanen, Harri

    2012-03-01

    We demonstrate nonlinear behavior in three-terminal T-branch graphene devices at room temperature. A rectified nonlinear output at the center branch is observed when the device is biased by a push-pull configuration. Nonlinearity is assumed to arise from a difference in charge transfer through the metal-graphene contact barrier between two contacts. The sign of the rectification can be altered by changing the carrier type using the back-gate voltage.

  17. Analysis of Dynamic Model of a Structure with Nonlinear Damped Behavior

    Directory of Open Access Journals (Sweden)

    G. Domairry

    2010-04-01

    Full Text Available In this work, it has been attempted to analytically treat the nonlinear behavior of structures. Since analysing nonlinear problems is of great difficulty, different numerical methods and software are advised to treat such problems. Despite the increasing expenses of building structures to maintain their linear behavior, nonlinearity has been inevitable, and therefore, nonlinear analysis has beenof great importance to the scientists in the field. As structures confront lateral forces and intense earthquakes especially near fault regions, a part of the structure remains linear, but some part of itbehaves nonlinearly for example dampers, columns and beams. This is simulated by a damped in nonlinear oscillator. In this paper, the nonlinear equation of oscillator with damping which has nonlinear behavior is representative of the dynamic behavior of a structure has been solved analytically. In the end, the obtained results are compared with numerical ones and shown in graphs and in tables;analytical solutions are in good agreement with those of the numerical method.

  18. Measurements and Modeling of the Nonlinear Behavior of a Guitar Pickup at Low Frequencies †

    Directory of Open Access Journals (Sweden)

    Antonin Novak

    2017-01-01

    Full Text Available Description of the physical behavior of electric guitars is still not very widespread in the scientific literature. In particular, the physical models describing a nonlinear behavior of pickups still requires some refinements. The study presented in this paper is focused on nonlinear modeling of the pickups. Two main issues are raised. First, is the currently most used nonlinear model (a Hammerstein model sufficient for the complex nonlinear behavior of the pickup? In other words, would a more complex model, such as a Generalized Hammerstein that can deal better with the nonlinear memory, yield better results? The second troublesome issue is how to measure the nonlinear behavior of a pickup correctly. A specific experimental set-up allowing for driving the pickup in a controlled way (string displacement perpendicular to the pickup and to separate the nonlinear model of the pickup from other nonlinearities in the measurement chain is proposed. Thanks to this experimental set-up, a Generalized Hammerstein model of the pickup is estimated for frequency range 15–500 Hz and the results are compared with a simple Hammerstein model. A comparison with experimental results shows that both models succeed in describing the pickup when used in realistic conditions.

  19. Asymptotic behavior of a nonlinear functional-integral equation of cell kinetics with unequal division.

    Science.gov (United States)

    Arino, O; Kimmel, M

    1989-01-01

    A model of cell cycle kinetics is proposed, which includes unequal division of cells, and a nonlinear dependence of the fraction of cells re-entering proliferation on the total number of cells in the cycle. The model is described by a nonlinear functional-integral equation. It is analyzed using the operator semigroup theory combined with classical differential equations approach. A complete description of the asymptotic behavior of the model is provided for a relatively broad class of nonlinearities. The nonnegative solutions either tend to a stable steady state, or to zero. The simplicity of the model makes it an interesting step in the analysis of dynamics of nonlinear structure populations.

  20. Dynamical Behavior of Nonlinear Viscoelastic Timoshenko Beams with Damage on a Viscoelastic Foundation

    Institute of Scientific and Technical Information of China (English)

    盛冬发; 张燕; 程昌钧

    2004-01-01

    Based on convolution-type constitutive equations for linear viscoelastic materials with damage and the hypotheses of Timoshenko beams with large deflections, the nonlinear equations governing dynamical behavior of Timoshenko beams with damage on viscoelastic foundation were firstly derived. By using the Galerkin method in spatial domain, the nonlinear integro-partial differential equations were transformed into a set of integro-ordinary differential equations. The numerical methods in nonlinear dynamical systems, such as the phase-trajectory diagram, Poincare section and bifurcation figure, were used to solve the simplified systems of equations. It could be seen that simplified dynamical systems possess the plenty of nonlinear dynamical properties. The influence of load and material parameters on the dynamic behavior of nonlinear system were investigated in detail.

  1. Nonlinear behavior analysis of spur gear pairs with a one-way clutch

    Science.gov (United States)

    Gill-Jeong, Cheon

    2007-04-01

    Nonlinear behavior analysis of a paired spur gear system with a one-way clutch was used to verify whether a one-way clutch is effective for reducing torsional vibration. The dynamic responses were studied over a wide frequency range by speed sweeping to check the nonlinear behavior using numerical integration. The gear system with a one-way clutch showed typical nonlinear behavior, such as softening nonlinearity and jump phenomena. The oscillating component of the dynamic transmission error was reduced over the entire frequency range compared to a system without a one-way clutch, and double-side contact could be prevented, even with very small backlash. Installing a one-way clutch on both sides of the gear system was more effective at mitigating the negative effects of various parameter changes than installing one only on the input or output side.

  2. An analysis of nonlinear behavior in delta-sigma modulators

    Science.gov (United States)

    Ardalan, Sasan H.; Paulos, John J.

    1987-06-01

    The paper introduces a new method of analysis for delta-sigma modulators based on modeling the nonlinear quantizer with a linearized gain, obtained by minimizing a mean-square-error criterion, followed by an additive noise source representing distortion components. In the paper, input signal amplitude dependencies of delta-sigma modulator stability and signal-to-noise ratio are analyzed. It is shown that due to the nonlinearity of the quantizer, the signal-to-noise ratio of the modulator may decrease as the input amplitude increases prior to saturation. Also, a stable third-order delta-sigma modulator may become unstable by increasing the input amplitude beyond a certain threshold. Both of these phenomena are explained by the nonlinear analysis of this paper. The analysis is carried out for both dc and sinusoidal excitations.

  3. Decoupling Nonclassical Nonlinear Behavior of Elastic Wave Types

    Science.gov (United States)

    Remillieux, Marcel C.; Guyer, Robert A.; Payan, Cédric; Ulrich, T. J.

    2016-03-01

    In this Letter, the tensorial nature of the nonequilibrium dynamics in nonlinear mesoscopic elastic materials is evidenced via multimode resonance experiments. In these experiments the dynamic response, including the spatial variations of velocities and strains, is carefully monitored while the sample is vibrated in a purely longitudinal or a purely torsional mode. By analogy with the fact that such experiments can decouple the elements of the linear elastic tensor, we demonstrate that the parameters quantifying the nonequilibrium dynamics of the material differ substantially for a compressional wave and for a shear wave. This result could lead to further understanding of the nonlinear mechanical phenomena that arise in natural systems as well as to the design and engineering of nonlinear acoustic metamaterials.

  4. Numerical insight into the seismic behavior of eight masonry towers in Northern Italy: FE pushover vs non-linear dynamic analyses

    Energy Technology Data Exchange (ETDEWEB)

    Milani, Gabriele, E-mail: milani@stru.polimi.it, E-mail: gabriele.milani@polimi.it; Valente, Marco [Department of Architecture, Built Environment and Construction Engineering (ABC), Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milan (Italy)

    2015-12-31

    This study presents some FE results regarding the behavior under horizontal loads of eight existing masonry towers located in the North-East of Italy. The towers, albeit unique for geometric and architectural features, show some affinities which justify a comparative analysis, as for instance the location and the similar masonry material. Their structural behavior under horizontal loads is therefore influenced by geometrical issues, such as slenderness, walls thickness, perforations, irregularities, presence of internal vaults, etc., all features which may be responsible for a peculiar output. The geometry of the towers is deduced from both existing available documentation and in-situ surveys. On the basis of such geometrical data, a detailed 3D realistic mesh is conceived, with a point by point characterization of each single geometric element. The FE models are analysed under seismic loads acting along geometric axes of the plan section, both under non-linear static (pushover) and non-linear dynamic excitation assumptions. A damage-plasticity material model exhibiting softening in both tension and compression, already available in the commercial code Abaqus, is used for masonry. Pushover analyses are performed with both G1 and G2 horizontal loads distribution, according to Italian code requirements, along X+/− and Y+/− directions. Non-linear dynamic analyses are performed along both X and Y directions with a real accelerogram scaled to different peak ground accelerations. Some few results are presented in this paper. It is found that the results obtained with pushover analyses reasonably well fit expensive non-linear dynamic simulations, with a slightly less conservative trend.

  5. Exposing the nonlinear viscoelastic behavior of asphalt-aggregate mixes

    Science.gov (United States)

    Levenberg, Eyal; Uzan, Jacob

    2012-05-01

    In this study asphalt-aggregate mixes are treated as both viscoelastic and viscoplastic. Following a damage mechanics approach, a nonlinear viscoelastic constitutive formulation is generated from a linear formulation by replacing `applied stresses' with `effective viscoelastic stresses'. A non-dimensional scalar entity called `relative viscoelastic stiffness' is introduced; it is defined as the ratio of applied to effective viscoelastic stress and encapsulates different types of nonlinearities. The paper proposes a computational scheme for exposing these nonlinearities by uncovering, through direct analysis of any test data, changes experienced by the `relative viscoelastic stiffness'. In general terms, the method is based on simultaneous application of creep and relaxation formulations while preserving the interrelationship between the corresponding time functions. The proposed scheme is demonstrated by analyzing a uniaxial tension test and a uniaxial compression test (separately). Results are presented and discussed, unveiling and contrasting the character of viscoelastic nonlinearities in both cases. A conceptual viewpoint is offered to explain the observations, illustrating the requirements from any candidate constitutive theory.

  6. Nonlinear elastic behavior of phantom materials for elastography

    Energy Technology Data Exchange (ETDEWEB)

    Pavan, Theo Z; Madsen, Ernest L; Frank, Gary R; Hall, Timothy J [Medical Physics Department, University of Wisconsin, Room 1005, Wisconsin Institutes for Medical Research, 1111 Highland Avenue, Madison, WI 53705 (United States); Adilton O Carneiro, Antonio, E-mail: tjhall@wisc.ed [Departamento de Fisica e Matematica, FFCLRP, Universidade de Sao Paulo, Av. Bandeirantes, 3900, Monte Alegre, Ribeirao Preto, Sao Paulo (Brazil)

    2010-05-07

    The development of phantom materials for elasticity imaging is reported in this paper. These materials were specifically designed to provide nonlinear stress/strain relationship that can be controlled independently of the small strain shear modulus of the material. The materials are mixtures of agar and gelatin gels. Oil droplet dispersions in these materials provide further control of the small strain shear modulus and the nonlinear parameter of the material. Since these materials are mostly water, they are assumed to be incompressible under typical experimental conditions in elasticity imaging. The Veronda-Westman model for strain energy density provided a good fit to all materials used in this study. Materials with a constant gelatin concentration (3.0% dry weight) but varying agar concentration (0.6-2.8% dry weight) demonstrated the same power law relationship between elastic modulus and agar concentration found for pure agar (1.89 {+-} 0.02), consistent with percolation theory, and provided a consistent nonlinearity parameter of 4.5 {+-} 0.3. The insights provided by this study will form the basis for stable elastography phantoms with stiffness and nonlinear stress/strain relationships in the background that differ from those in the target.

  7. The Behavior of Indonesian Stock Market: Structural Breaks and Nonlinearity

    Directory of Open Access Journals (Sweden)

    Rahmat Heru Setianto

    2011-09-01

    Full Text Available This study empirically examines the behaviour of Indonesian stock market under the efficient market hypothesis framework by emphasizing on the random walk behaviour and nonlinearity over the period of April 1983 - December 2010. In the first step, the standard linear unit root test, namely the augmented Dickey-Fuller (ADF test, Phillip-Perron (PP test and Kwiatkowski-Philllips-Schmidt-Shin (KPSS test identify the random walk behaviour in the indices. In order to take account the possible breaks in the index series Zivot and Adrews (1992 one break and Lumsdaine and Papell (1997 two breaks unit root test are employed to observe whether the presence of breaks in the data series will prevent the stocks from randomly pricing or vice versa. In the third step, we employ Harvey et al. (2008 test to examine the presence of nonlinear behaviour in Indonesian stock indices. The evidence of nonlinear behaviour in the indices, motivate us to use nonlinear unit root test procedure recently developed by Kapetanios et al. (2003 and Kruse (2010. In general, the results from standard linear unit root test, Zivot and Adrews (ZA test and Lumsdaine and Papell (LP test provide evidence that Jakarta Composite Index characterized by a unit root. In addition, structural breaks identified by ZA and LP test are corresponded to the events of financial market liberalization and financial crisis. The nonlinear unit root test procedure fail to rejects the null hypothesis of unit root for all indices, suggesting that Jakarta Composite Index characterized by random walk process supporting the theory of efficient market hypothesis.

  8. Oscillatory and Asymptotic Behavior of a Second-Order Nonlinear Functional Differential Equations

    Institute of Scientific and Technical Information of China (English)

    张全信; 高丽; 王少英

    2012-01-01

    This paper is concerned with oscillatory and asymptotic behavior of solutions of a class of second order nonlinear functional differential equations. By using the generalized Riccati transformation and the integral averaging technique, new oscillation criteria and asymptotic behavior are obtained for all solutions of the equation. Our results generalize and improve some known theorems.

  9. Strategies in Perforated Diverticulitis

    NARCIS (Netherlands)

    J. Vermeulen (Jefrey)

    2010-01-01

    textabstractAlthough diverticulitis is a common disease affecting the gastrointestinal tract, few is known about the optimal surgical treatment of its most severe form: perforated diverticulitis. Regardless of the selected operation, perforated diverticulitis is associated with mortality rates up to

  10. Pedicled perforator flaps

    DEFF Research Database (Denmark)

    Demirtas, Yener; Ozturk, Nuray; Kelahmetoglu, Osman;

    2009-01-01

    Described in this study is a surgical concept that supports the "consider and use a pedicled perforator flap whenever possible and indicated" approach to reconstruct a particular skin defect. The operation is entirely free-style; the only principle is to obtain a pedicled perforator flap to recon......Described in this study is a surgical concept that supports the "consider and use a pedicled perforator flap whenever possible and indicated" approach to reconstruct a particular skin defect. The operation is entirely free-style; the only principle is to obtain a pedicled perforator flap...... more practical and creative to use a free-style manner during pedicled perforator flap surgery, instead of being obliged to predefined templates for this type of procedure....

  11. WAVE INTERACTION WITH PERFORATED CAISSON BREAKWATERS

    Institute of Scientific and Technical Information of China (English)

    Chen Xue-feng

    2003-01-01

    The reflection coefficient of perforated caissons and the total horizontal forces acting on them were experimentally and numerically analyzed and discussed when wave propagates normally. To consider the viscosity effect of fluid and nonlinear action of waves on structures, the VOF (Volume Of Fluid) method combined with the k-ε turbulence model was used to simulate the interaction between waves and structures. Governing equations were solved with the finite difference method. Through 2D experimental study in the wave flume, the empirical relationship between the reflection coefficient of perforated caissons and the main affecting factors were obtained from the experimental data using the least square method. Also the correlation between the ratio of the total horizontal force acting on perforated caisson and the force acting on solid caisson and the main affecting factors were regressed from the experimental data.

  12. ANALYSIS OF THE ACOUSTIC BEHAVIOR OF MULTILAYER PANELS WITH PERFORATED SHEET METAL FAÇADE ELEMENT AS COMPARED TO THE OUTSIDE NOISE

    Directory of Open Access Journals (Sweden)

    ALINA – ELENA CRETU

    2016-06-01

    Full Text Available This project is a study about covering both structural and economical requirements in order to enhance the utility and pleasure of a perforated metal façade. Optimizes the use of the elements of the multilayer panels and are part of the facade of many buildings, based on the criterion of sound absorption of these multilayer boards which use perforated sheet mainly for esthetic reasons and thermal.

  13. Swarming behaviors in multi-agent systems with nonlinear dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Wenwu, E-mail: wenwuyu@gmail.com [Department of Mathematics, Southeast University, Nanjing 210096 (China); School of Electrical and Computer Engineering, RMIT University, Melbourne VIC 3001 (Australia); Chen, Guanrong [Department of Electronic Engineering, City University of Hong Kong, Hong Kong (China); Cao, Ming [Faculty of Mathematics and Natural Sciences, ITM, University of Groningen (Netherlands); Lü, Jinhu [Institute of Systems Science, Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing 100190 (China); Zhang, Hai-Tao [Department of Control Science and Engineering, State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2013-12-15

    The dynamic analysis of a continuous-time multi-agent swarm model with nonlinear profiles is investigated in this paper. It is shown that, under mild conditions, all agents in a swarm can reach cohesion within a finite time, where the upper bounds of the cohesion are derived in terms of the parameters of the swarm model. The results are then generalized by considering stochastic noise and switching between nonlinear profiles. Furthermore, swarm models with limited sensing range inducing changing communication topologies and unbounded repulsive interactions between agents are studied by switching system and nonsmooth analysis. Here, the sensing range of each agent is limited and the possibility of collision among nearby agents is high. Finally, simulation results are presented to demonstrate the validity of the theoretical analysis.

  14. Nonlinear dynamical behavior of shallow cylindrical reticulated shells

    Institute of Scientific and Technical Information of China (English)

    WANG Xin-zhi; LIANG Cong-xing; HAN Ming-jun; YEH Kai-yuan; WANG Gang

    2007-01-01

    By using the method of quasi-shells , the nonlinear dynamic equations of three-dimensional single-layer shallow cylindrical reticulated shells with equilateral triangle cell are founded. By using the method of the separating variable function, the transverse displacement of the shallow cylindrical reticulated shells is given under the conditions of two edges simple support. The tensile force is solved out from the compatible equations, a nonlinear dynamic differential equation containing second and third order is derived by using the method of Galerkin. The stability near the equilibrium point is discussed by solving the Floquet exponent and the critical condition is obtained by using Melnikov function. The existence of the chaotic motion of the single-layer shallow cylinmapping.

  15. Swarming behaviors in multi-agent systems with nonlinear dynamics.

    Science.gov (United States)

    Yu, Wenwu; Chen, Guanrong; Cao, Ming; Lü, Jinhu; Zhang, Hai-Tao

    2013-12-01

    The dynamic analysis of a continuous-time multi-agent swarm model with nonlinear profiles is investigated in this paper. It is shown that, under mild conditions, all agents in a swarm can reach cohesion within a finite time, where the upper bounds of the cohesion are derived in terms of the parameters of the swarm model. The results are then generalized by considering stochastic noise and switching between nonlinear profiles. Furthermore, swarm models with limited sensing range inducing changing communication topologies and unbounded repulsive interactions between agents are studied by switching system and nonsmooth analysis. Here, the sensing range of each agent is limited and the possibility of collision among nearby agents is high. Finally, simulation results are presented to demonstrate the validity of the theoretical analysis.

  16. Asymptotic Behavior of Solutions for Nonlinear Volterra Discrete Equations

    Directory of Open Access Journals (Sweden)

    E. Messina

    2008-01-01

    Full Text Available We consider nonlinear difference equations of unbounded order of the form xi=bi−∑j=0iai,jfi−j(xj,  i=0,1,2,…, where fj(x  (j=0,…,i are suitable functions. We establish sufficient conditions for the boundedness and the convergence of xi as i→+∞. Some of these conditions are interesting mainly for studying stability of numerical methods for Volterra integral equations.

  17. Analysis of fractional non-linear diffusion behaviors based on Adomian polynomials

    Directory of Open Access Journals (Sweden)

    Wu Guo-Cheng

    2017-01-01

    Full Text Available A time-fractional non-linear diffusion equation of two orders is considered to investigate strong non-linearity through porous media. An equivalent integral equation is established and Adomian polynomials are adopted to linearize non-linear terms. With the Taylor expansion of fractional order, recurrence formulae are proposed and novel numerical solutions are obtained to depict the diffusion behaviors more accurately. The result shows that the method is suitable for numerical simulation of the fractional diffusion equations of multi-orders.

  18. Nonlinear behavior of electron acoustic waves in an un-magnetized plasma

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, Manjistha; Khan, Manoranjan [Department of Instrumentation Science, Jadavpur University, Kolkata 700 032 (India); Chakrabarti, Nikhil [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India); Roychoudhury, Rajkumar [Indian Statistical Institute, Kolkata 700 108 (India)

    2011-10-15

    The nonlinear electron acoustic wave, which is found in the earth's magnetosphere by satellite observations, is studied analytically by Lagrangian fluid description. The basic linear mode is observed in a two temperature electron species plasma where ions form stationary charge neutral background. We have obtained nonlinear description of this mode, which depends on both time and space. A possible solution shows a soliton like structure, which is localized in space, and the amplitude increases with time in the absence of dispersion. Small dispersive correction, however, shows spread of the solution in space. This method can be generalized to study the nonlinear behavior of a general class of multispecies plasma.

  19. Nonlinear Dynamical Behavior in BS Evolution Model Based on Small-World Network Added with Nonlinear Preference

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ying-Yue; YANG Qiu-Ying; CHEN Tian-Lun

    2007-01-01

    We introduce a modified small-world network adding new links with nonlinearly preferential connection instead of adding randomly, then we apply Bak-Sneppen (BS) evolution model on this network. We study several important structural properties of our network such as the distribution of link-degree, the maximum link-degree, and the length of the shortest path. We further argue several dynamical characteristics of the model such as the important critical value fc, the f0 avalanche, and the mutating condition, and find that those characteristics show particular behaviors.

  20. Multiscale Study of the Nonlinear Behavior of Heterogeneous Clayey Rocks Based on the FFT Method

    Science.gov (United States)

    Jiang, Tao; Xu, Weiya; Shao, Jianfu

    2015-03-01

    A multiscale model based on the fast Fourier transform (FFT) is applied to study the nonlinear mechanical behavior of Callovo-Oxfordian (COx) argillite, a typical heterogeneous clayey rocks. COx argillite is modeled as a three-phase composite with a clay matrix and two types of mineral inclusions. The macroscopic mechanical behavior of argillite samples with different mineralogical compositions are satisfactorily predicted by unified local constitutive models and material parameters. Moreover, the numerical implementation of the FFT-based nonlinear homogenization is easier than direct homogenization, such as the FEM-based homogenization, because it automatically satisfies the periodic boundary condition.

  1. Mean-field theory of strongly nonlinear random composites: Strong power-law nonlinearity and scaling behavior

    Science.gov (United States)

    Wan, W. M. V.; Lee, H. C.; Hui, P. M.; Yu, K. W.

    1996-08-01

    The effective response of random media consisting of two different kinds of strongly nonlinear materials with strong power-law nonlinearity is studied. Each component satisfies current density and electric-field relation of the form J=χ\\|E\\|βE. A simple self-consistent mean-field theory, which leads to a simple way in determining the average local electric field in each constituent, is introduced. Each component is assumed to have a conductivity depending on the averaged local electric field. The averaged local electric field is then determined self-consistently. Numerical simulations of the system are carried out on random nonlinear resistor networks. Theoretical results are compared with simulation data, and excellent agreements are found. Results are also compared with the Hashin-Shtrikman lower bound proposed by Ponte Castaneda et al. [Phys. Rev. B 46, 4387 (1992)]. It is found that the present theory, at small contrasts of χ between the two components, gives a result identical to that of Ponte Castaneda et al. up to second order of the contrast. The crossover and scaling behavior of the effective response near the percolation threshold as suggested by the present theory are discussed and demonstrated.

  2. Understanding of flux-limited behaviors of heat transport in nonlinear regime

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yangyu, E-mail: yangyuhguo@gmail.com [Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Engineering Mechanics and CNMM, Tsinghua University, Beijing 100084 (China); Jou, David, E-mail: david.jou@uab.es [Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia (Spain); Wang, Moran, E-mail: mrwang@tsinghua.edu [Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Engineering Mechanics and CNMM, Tsinghua University, Beijing 100084 (China)

    2016-01-28

    The classical Fourier's law of heat transport breaks down in highly nonequilibrium situations as in nanoscale heat transport, where nonlinear effects become important. The present work is aimed at exploring the flux-limited behaviors based on a categorization of existing nonlinear heat transport models in terms of their theoretical foundations. Different saturation heat fluxes are obtained, whereas the same qualitative variation trend of heat flux versus exerted temperature gradient is got in diverse nonlinear models. The phonon hydrodynamic model is proposed to act as a standard to evaluate other heat flux limiters because of its more rigorous physical foundation. A deeper knowledge is thus achieved about the phenomenological generalized heat transport models. The present work provides deeper understanding and accurate modeling of nonlocal and nonlinear heat transport beyond the diffusive limit. - Highlights: • Exploring flux-limited behaviors based on a categorization of existing nonlinear heat transport models. • Proposing phonon hydrodynamic model as a standard to evaluate heat flux limiters. • Providing accurate modeling of nonlocal and nonlinear heat transport beyond the diffusive limit.

  3. PATH INTEGRAL SOLUTION OF NONLINEAR DYNAMIC BEHAVIOR OF STRUCTURE UNDER WIND EXCITATION

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    A numerical scheme for the nonlinear behavior of structure under wind excitation is investigated. With the white noise filter of turbulent-wind fluctuations, the nonlinear motion equation of structures subjected to wind load was modeled as the Ito' s stochastic differential equation. The state vector associated with such a model is a diffusion process. A continuous linearization strategy in the time-domain was adopted.Based on the solution series of its stochastic linearization equations, the formal probabilistic density of the structure response was developed by the path integral technique. It is shown by the numerical example of a guyed mast that compared with the frequency-domain method and the time-domain nonlinear analysis, the proposed approach is highlighted by high accuracy and effectiveness. The influence of the structure non-linearity on the dynamic reliability assessment is also analyzed in the example.

  4. Ambiguities in input-output behavior of driven nonlinear systems close to bifurcation

    Directory of Open Access Journals (Sweden)

    Reit Marco

    2016-06-01

    Full Text Available Since the so-called Hopf-type amplifier has become an established element in the modeling of the mammalian hearing organ, it also gets attention in the design of nonlinear amplifiers for technical applications. Due to its pure sinusoidal response to a sinusoidal input signal, the amplifier based on the normal form of the Andronov-Hopf bifurcation is a peculiar exception of nonlinear amplifiers. This feature allows an exact mathematical formulation of the input-output characteristic and thus deeper insights of the nonlinear behavior. Aside from the Hopf-type amplifier we investigate an extension of the Hopf system with focus on ambiguities, especially the separation of solution sets, and double hysteresis behavior in the input-output characteristic. Our results are validated by a DSP implementation.

  5. Analysis of the nonlinear behavior of adhesives in bonded assemblies - Comparison of TAST and Arcan tests

    OpenAIRE

    Cognard, J; Creac' Hcadec, R; Sohier, L; Davies, Peter

    2008-01-01

    This paper describes a study in which the shear behavior of a structural epoxy adhesive has been measured using the standard thick adherend shear test (TAST) specimen and a modified Arcan test A. numerical study of the TAST test taking into account the nonlinear behavior of the adhesive and the finite deformations of the adhesive joint, shows that there is a localization of plastic zones close to the adhesive-substrate interface near the free edge of the adhesive. Experimental tests carried o...

  6. Nonlinear Dynamical Behavior in Neuron Model Based on Small World Network with Attack and Repair Strategy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xue; YANG Qiu-Ying; ZHENG Tai-Yu; ZHANG Ying-Yue; ZHENG Li; ZHANG Gui-Qing; CHEN Tian-Lun

    2008-01-01

    In this paper, we investigate the effect due to the change of topology structure of network on the nonlinear dynamical behavior, by virtue of the OFC neuron evolution model with attack and repair strategy based on the small world. In particular, roles of various parameters relating to the dynamical behavior are carefully studied and analyzed. In addition, the avalanche and EEG-like wave activities with attack and repair strategy are also explored in detail in this work.

  7. Nanomodeling of Nonlinear Thermoelastic Behavior of AA5454/ Silicon Nitride Nanoparticulate Metal Matrix Composites

    Directory of Open Access Journals (Sweden)

    Chennakesava R Alavala

    2016-01-01

    Full Text Available The aim of the present work was to estimate non-linear thermoelastic behavior of three-phase AA5454/silicon nitride nanoparticle metal matrix composites. The thermal loading was varied from subzero temperature to under recrystallization temperature. The RVE models were used to analyze thermo-elastic behavior. The AA5454/silicon nitride nanoparticle metal matrix composites have gained the elastic modulus below 0oC and lost at high temperatures.

  8. Complex Nonlinear Behavior in Metabolic Processes: Global Bifurcation Analysis of Escherichia coli Growth on Multiple Substrates

    Directory of Open Access Journals (Sweden)

    Hyun-Seob Song

    2013-09-01

    Full Text Available The nonlinear behavior of metabolic systems can arise from at least two different sources. One comes from the nonlinear kinetics of chemical reactions in metabolism and the other from nonlinearity associated with regulatory processes. Consequently, organisms at a constant growth rate (as experienced in a chemostat could display multiple metabolic states or display complex oscillatory behavior both with potentially serious implications to process operation. This paper explores the nonlinear behavior of a metabolic model of Escherichia coli growth on mixed substrates with sufficient detail to include regulatory features through the cybernetic postulate that metabolic regulation is the consequence of a dynamic objective function ensuring the organism’s survival. The chief source of nonlinearity arises from the optimal formulation with the metabolic state determined by a convex combination of reactions contributing to the objective function. The model for anaerobic growth of E. coli was previously examined for multiple steady states in a chemostat fed by a mixture of glucose and pyruvate substrates under very specific conditions and experimentally verified. In this article, we explore the foregoing model for nonlinear behavior over the full range of parameters, γ (the fractional concentration of glucose in the feed mixture and D (the dilution rate. The observed multiplicity is in the cybernetic variables combining elementary modes. The results show steady-state multiplicity up to seven. No Hopf bifurcation was encountered, however. Bifurcation analysis of cybernetic models is complicated by the non-differentiability of the cybernetic variables for enzyme activities. A methodology is adopted here to overcome this problem, which is applicable to more complicated metabolic networks.

  9. Asymptotic Behavior of Equilibrium Point for a Class of Nonlinear Difference Equation

    Directory of Open Access Journals (Sweden)

    Gong Fei

    2009-01-01

    Full Text Available We study the asymptotic behavior of the solutions for the following nonlinear difference equation where the initial conditions are arbitrary nonnegative real numbers, are nonnegative integers, , and are positive constants. Moreover, some numerical simulations to the equation are given to illustrate our results.

  10. Asymptotic Behavior of Global Solution for Nonlinear Generalized Euler-Possion-Darboux Equation

    Institute of Scientific and Technical Information of China (English)

    LIANGBao-song; CHENZhen

    2004-01-01

    J. L Lions and W. A. Stranss [1] have proved the existence of a global solution of the initial boundary value problem for nonlinear generalized Euler-Possion-Darboux equation. In this paper we are going to investigate the asymptotic behavior of the global solution by a difference inequality.

  11. Oscillatory and Asymptotic Behavior of Solutions for Nonlinear Impulsive Delay Differential Equations

    Institute of Scientific and Technical Information of China (English)

    Wei-hua Mao; An-hua Wan

    2006-01-01

    The oscillatory and asymptotic behavior of the solutions for third order nonlinear impulsive delay differential equations are investigated. Some novel criteria for all solutions to be oscillatory or be asymptotic are established. Three illustrative examples are proposed to demonstrate the effectiveness of the conditions.

  12. Modeling the nonlinear PMMA behavior near glass transition temperature: application to its thermoforming

    Science.gov (United States)

    Gilormini, P.; Chevalier, L.; Régnier, G.

    2011-01-01

    Using suitable constitutive equations, numerical simulation allows predicting the properties of transparencies that are thermoformed near their glass transition temperature. Such equations are presented, which describe the nonlinear viscoelastic behavior of poly(methyl methacrylate) at large deformations near glass transition. The simulation of the thermoforming of a transparency at constant and uniform temperature is performed and compared with experimental results.

  13. Effects of graphene quantum dots on linear and nonlinear optical behavior of malignant ovarian cells

    Science.gov (United States)

    Mohajer, Salman; Ara, Mohammad Hossein Majles; Serahatjoo, Leila

    2016-07-01

    We investigate linear and nonlinear optical properties of standard human ovarian cancer cells (cell line: A2780cp) in vitro. Cells were treated by graphene quantum dots (GQDs) with two special concentrations. Nontoxicity of GQDs was examined in standard biological viability tests. Cancerous cells were fixed on a glass slide; then, interaction of light with biofilms was studied in linear and nonlinear regimes. Absorption spectra of untreated biofilms and biofilms with two different concentrations of GQDs was studied by UV-visible spectrophotometer. Optical behavior of biofilms in a linear regime of intensity (with low-intensity laser exposure) was reported using a simple optical setup. After that, we compared the attenuation of light in biofilm of cancerous cells with and without GQDs. Nonlinear behavior of these biofilms was investigated by a Z-scan setup using a continued wave He-Ne laser. Results showed that GQDs decreased the extinction coefficient and changed the sign and exact value of the nonlinear refractive index of malignant ovarian cells noticeably. The nonlinear refractive index of studied cells with no GQDs treatment was in the order of 10-8 (cm2/w) with a positive sign. This quantity changed to the same order of magnitude with a negative sign after GQDs treatment. Thus, GQDs can be used for cancer diagnosis under laser irradiation.

  14. Study of nonlinear behaviors and modal reductions for friction destabilized systems. Application to an elastic layer

    Science.gov (United States)

    Loyer, A.; Sinou, J.-J.; Chiello, O.; Lorang, X.

    2012-02-01

    As noise reduction tends to be part of environmental directives, predicting squeal noise generated by disc brakes is an important industrial issue. It involves both the transient and stationary nonlinear dynamics of self-excited systems with frictional contact. Time simulation of the phenomenon is an attractive option for reducing experiment costs. However, since such computations using full finite element models of industrial disc brake systems is time-consuming, model reduction has to be performed. In this paper, both the transient and stationary nonlinear behaviors of the friction destabilized system and the effect of dynamical reduction on the nonlinear response of a simple friction destabilized system are carried out. The first part provides a description of the general modeling retained for friction destabilized systems. Then, discretization and solving processes for the stability analysis and the temporal evolution are presented. The third part presents an analysis of a sliding elastic layer for different operating conditions, in order to better understand the nonlinear behavior of such systems. Finally, spatial model reduction is performed with different kinds of reduction bases in order to analyze the different effects of modal reductions. This clearly shows the necessity of including static modes in the reduction basis and that nonlinear interactions between unstable modes are very difficult to represent with reduced bases. Finally, the proposed model and the associated studies are intended to be the benchmark cases for future comparison.

  15. Nonlinear Dynamic Behaviors of Rotated Blades with Small Breathing Cracks Based on Vibration Power Flow Analysis

    Directory of Open Access Journals (Sweden)

    Hailong Xu

    2016-01-01

    Full Text Available Rotated blades are key mechanical components in turbomachinery and high cycle fatigues often induce blade cracks. Accurate detection of small cracks in rotated blades is very significant for safety, reliability, and availability. In nature, a breathing crack model is fit for a small crack in a rotated blade rather than other models. However, traditional vibration displacements-based methods are less sensitive to nonlinear characteristics due to small breathing cracks. In order to solve this problem, vibration power flow analysis (VPFA is proposed to analyze nonlinear dynamic behaviors of rotated blades with small breathing cracks in this paper. Firstly, local flexibility due to a crack is derived and then time-varying dynamic model of the rotated blade with a small breathing crack is built. Based on it, the corresponding vibration power flow model is presented. Finally, VPFA-based numerical simulations are done to validate nonlinear behaviors of the cracked blade. The results demonstrate that nonlinear behaviors of a crack can be enhanced by power flow analysis and VPFA is more sensitive to a small breathing crack than displacements-based vibration analysis. Bifurcations will occur due to breathing cracks and subharmonic resonance factors can be defined to identify breathing cracks. Thus the proposed method can provide a promising way for detecting and predicting small breathing cracks in rotated blades.

  16. Nonlinear Dynamics Behaviors of a Rotor Roller Bearing System with Radial Clearances and Waviness Considered

    Institute of Scientific and Technical Information of China (English)

    Wang Liqin; Cui Li; Zheng Dezhi; Gu Le

    2008-01-01

    A rotor system supported by roller bearings displays very complicated nonlinear behaviors due to nonlinear Hertzian contact forces, radial clearances and bearing waviness. This paper presents nonlinear bearing forces of a roller bearing under four-dimensional loads and establishes 4-DOF dynamics equations of a rotor roller bearing system. The methods of Newmark-β and of Newton-Laphson are used to solve the nonlinear equations. The dynamics behaviors of a rigid rotor system are studied through the bifurcation, the Poincar bility caused by the quasi-periodic bifurcation, the periodic-doubling bifurcation and chaos routes as the rotational speed increases.Clearances, outer race waviness, inner race waviness, roller waviness, damping, radial forces and unbalanced forces-all these bring a significant influence to bear on the system stability. As the clearance increases, the dynamics behaviors become complicated with the number and the scale of instable regions becoming larger. The vibration frequencies induced by the roller bearing waviness and the orders of the waviness might cause severe vibrations. The system is able to eliminate non-periodic vibration by reasonable choice and optimization of the parameters.

  17. Stability of Gain Scheduling Control for Aircraft with Highly Nonlinear Behavior

    Directory of Open Access Journals (Sweden)

    Fany Mendez-Vergara

    2014-01-01

    Full Text Available The main goal of this work is to study the stability properties of an aircraft with nonlinear behavior, controlled using a gain scheduled approach. An output feedback is proposed which is able to guarantee asymptotical stability of the task-coordinates origin and safety of the operation in the entire flight envelope. The results are derived using theory of hybrid and singular perturbed systems. It is demonstrated that both body velocity and orientation asymptotic tracking can be obtained in spite of nonlinearities and uncertainty. The results are illustrated using numerical simulations in F16 jet.

  18. STABILITY AND BIFURCATION BEHAVIORS ANALYSIS IN A NONLINEAR HARMFUL ALGAL DYNAMICAL MODEL

    Institute of Scientific and Technical Information of China (English)

    WANG Hong-li; FENG Jian-feng; SHEN Fei; SUN Jing

    2005-01-01

    A food chain made up of two typical algae and a zooplankton was considered. Based on ecological eutrophication, interaction of the algal and the prey of the zooplankton, a nutrient nonlinear dynamic system was constructed. Using the methods of the modern nonlinear dynamics, the bifurcation behaviors and stability of the model equations by changing the control parameter r were discussed. The value of r for bifurcation point was calculated, and the stability of the limit cycle was also discussed. The result shows that through quasi-periodicity bifurcation the system is lost in chaos.

  19. Nonlinear response of plain concrete shear walls with elastic-damaging behavior

    Energy Technology Data Exchange (ETDEWEB)

    Yazdani, S.; Schreyer, H.L.

    1997-02-01

    This report summarizes the theoretical and computational efforts on the modeling of small scale shear walls. Small scale shear walls are used extensively in the study of shear wall behavior because the construction and testing of full size walls are rather expensive. A finite element code is developed which incorporates nonlinear constitutive relations of damage mechanics. The program is used to obtain nonlinear load-deformation curves and to address the initial loss of stiffness due to shrinkage cracking. The program can also be used to monitor the continuous degradation of the fundamental frequency due to progressive damage.

  20. A molecular mechanics approach for analyzing tensile nonlinear deformation behavior of single-walled carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    Yu Wang; Daining Fang; Ai Kah Soh; Bin Liu

    2007-01-01

    In this paper, by capturing the atomic informa-tion and reflecting the behaviour governed by the nonlin-ear potential function, an analytical molecular mechanics approach is proposed. A constitutive relation for single-walled carbon nanotubes (SWCNT's) is established to describe the nonlinear stress-strain curve of SWCNT's and to predict both the elastic properties and breaking strain of SWCNT's during tensile deformation. An analysis based on the virtual internal bond (VIB) model proposed by P. Zhang et al. is also presented for comparison. The results indicate that the proposed molecular mechanics approach is indeed an acceptable analytical method for analyzing the mechanical behavior of SWCNT's.

  1. Nonlinear shear behavior of rock joints using a linearized implementation of the Barton–Bandis model

    Directory of Open Access Journals (Sweden)

    Simon Heru Prassetyo

    2017-08-01

    Full Text Available Experiments on rock joint behaviors have shown that joint surface roughness is mobilized under shearing, inducing dilation and resulting in nonlinear joint shear strength and shear stress vs. shear displacement behaviors. The Barton–Bandis (BB joint model provides the most realistic prediction for the nonlinear shear behavior of rock joints. The BB model accounts for asperity roughness and strength through the joint roughness coefficient (JRC and joint wall compressive strength (JCS parameters. Nevertheless, many computer codes for rock engineering analysis still use the constant shear strength parameters from the linear Mohr–Coulomb (M−C model, which is only appropriate for smooth and non-dilatant joints. This limitation prevents fractured rock models from capturing the nonlinearity of joint shear behavior. To bridge the BB and the M−C models, this paper aims to provide a linearized implementation of the BB model using a tangential technique to obtain the equivalent M−C parameters that can satisfy the nonlinear shear behavior of rock joints. These equivalent parameters, namely the equivalent peak cohesion, friction angle, and dilation angle, are then converted into their mobilized forms to account for the mobilization and degradation of JRC under shearing. The conversion is done by expressing JRC in the equivalent peak parameters as functions of joint shear displacement using proposed hyperbolic and logarithmic functions at the pre- and post-peak regions of shear displacement, respectively. Likewise, the pre- and post-peak joint shear stiffnesses are derived so that a complete shear stress-shear displacement relationship can be established. Verifications of the linearized implementation of the BB model show that the shear stress-shear displacement curves, the dilation behavior, and the shear strength envelopes of rock joints are consistent with available experimental and numerical results.

  2. Spontaneous Perforation of Pyometra.

    Science.gov (United States)

    Sharma, Nalini; Singh, Ahanthem Santa; Bhaphiralyne, Wankhar

    2016-04-01

    Pyometra is collection of purulent material which occurs when there is interference with its normal drainage. It is an uncommon condition with incidence of 0.1 to 0.5% of all gynecological patients. Spontaneous rupture of uterus is an extremely rare complication of pyometra. A 65-year-old lady presented with pain abdomen and purulent vaginal discharge. Preoperative diagnosis of pyometra was made by magnetic resonance imaging (MRI). Laparotomy followed by peritoneal lavage and repair of perforation was performed. Although spontaneously perforated pyometra is rare, the condition must be borne in mind with regard to elderly women with acute abdominal pain. Preoperative diagnosis of perforated pyometra is absolutely essential. Computed tomography (CT) and MRI are diagnostic tools. In selected cases conservative approach at surgery can be opted.

  3. Nonlinear threshold behavior during the loss of Arctic sea ice

    CERN Document Server

    Eisenman, I; 10.1073/pnas.0806887106

    2008-01-01

    In light of the rapid recent retreat of Arctic sea ice, a number of studies have discussed the possibility of a critical threshold (or "tipping point") beyond which the ice-albedo feedback causes the ice cover to melt away in an irreversible process. The focus has typically been centered on the annual minimum (September) ice cover, which is often seen as particularly susceptible to destabilization by the ice-albedo feedback. Here we examine the central physical processes associated with the transition from ice-covered to ice-free Arctic Ocean conditions. We show that while the ice-albedo feedback promotes the existence of multiple ice cover states, the stabilizing thermodynamic effects of sea ice mitigate this when the Arctic Ocean is ice-covered during a sufficiently large fraction of the year. These results suggest that critical threshold behavior is unlikely during the approach from current perennial sea ice conditions to seasonally ice-free conditions. In a further warmed climate, however, we find that a ...

  4. Nonlinear threshold behavior during the loss of Arctic sea ice.

    Science.gov (United States)

    Eisenman, I; Wettlaufer, J S

    2009-01-06

    In light of the rapid recent retreat of Arctic sea ice, a number of studies have discussed the possibility of a critical threshold (or "tipping point") beyond which the ice-albedo feedback causes the ice cover to melt away in an irreversible process. The focus has typically been centered on the annual minimum (September) ice cover, which is often seen as particularly susceptible to destabilization by the ice-albedo feedback. Here, we examine the central physical processes associated with the transition from ice-covered to ice-free Arctic Ocean conditions. We show that although the ice-albedo feedback promotes the existence of multiple ice-cover states, the stabilizing thermodynamic effects of sea ice mitigate this when the Arctic Ocean is ice covered during a sufficiently large fraction of the year. These results suggest that critical threshold behavior is unlikely during the approach from current perennial sea-ice conditions to seasonally ice-free conditions. In a further warmed climate, however, we find that a critical threshold associated with the sudden loss of the remaining wintertime-only sea ice cover may be likely.

  5. On the Nonlinear Behavior of the Piezoelectric Coupling on Vibration-Based Energy Harvesters

    Directory of Open Access Journals (Sweden)

    Luciana L. Silva

    2015-01-01

    Full Text Available Vibration-based energy harvesting with piezoelectric elements has an increasing importance nowadays being related to numerous potential applications. A wide range of nonlinear effects is observed in energy harvesting devices and the analysis of the power generated suggests that they have considerable influence on the results. Linear constitutive models for piezoelectric materials can provide inconsistencies on the prediction of the power output of the energy harvester, mainly close to resonant conditions. This paper investigates the effect of the nonlinear behavior of the piezoelectric coupling. A one-degree of freedom mechanical system is coupled to an electrical circuit by a piezoelectric element and different coupling models are investigated. Experimental tests available in the literature are employed as a reference establishing the best matches of the models. Subsequently, numerical simulations are carried out showing different responses of the system indicating that nonlinear piezoelectric couplings can strongly modify the system dynamics.

  6. Nonlinear light behaviors near phase transition in non-parity-time-symmetric complex waveguides

    CERN Document Server

    Nixon, Sean

    2016-01-01

    Many classes of non-parity-time (PT) symmetric waveguides with arbitrary gain and loss distributions still possess all-real linear spectrum or exhibit phase transition. In this article, nonlinear light behaviors in these complex waveguides are probed analytically near a phase transition. Using multi-scale perturbation methods, a nonlinear ordinary differential equation (ODE) is derived for the light's amplitude evolution. This ODE predicts that the first class of these non-PT-symmetric waveguides support continuous families of solitons and robust amplitude-oscillating solutions both above and below phase transition, in close analogy with PT-symmetric systems. For the other classes of waveguides, the light's intensity always amplifies under the effect of nonlinearity even if the waveguide is below phase transition. These analytical predictions are confirmed by direct computations of the full system.

  7. Nonlinear elastic behavior of rocks revealed by dynamic acousto-elastic testing

    Science.gov (United States)

    Shokouhi, Parisa; Riviere, Jacques; Guyer, Robert; Johnson, Paul

    2017-04-01

    Nonlinear elastic behavior of rocks is studied at the laboratory scale with the goal of illuminating observations at the Earth scale, for instance during strong ground motion and earthquake slip processes. A technique called Dynamic Acousto-Elastic Testing (DAET) is used to extract the nonlinear elastic response of disparate rocks (sandstone, granite and soapstone). DAET is the dynamic analogous to standard (quasi-static) acousto-elastic testing. It consists in measuring speed of sound with high-frequency low amplitude pulses (MHz range) across the sample while it is dynamically loaded with a low frequency, large amplitude resonance (kHz range). This particular configuration provides the instantaneous elastic response over a full dynamic cycle and reveals unprecedented details: instantaneous softening, tension/compression asymmetry as well as hysteretic behaviors. The strain-induced modulation of ultrasonic pulse velocities ('fast dynamics') is analyzed to extract nonlinearity parameters. A projection method is used to extract the harmonic content and a careful comparison of the fast dynamics response is made. In order to characterize the rate of elastic recovery ('slow dynamics'), we continue to monitor the ultrasonic wave velocity for about 30 minutes after the low-frequency resonance is turned off. In addition, the frequency, pressure and humidity dependences of the nonlinear parameters are reported for a subset of samples. We find that the nonlinear components can be clustered into two categories, which suggests that two main mechanisms are at play. The first one, related to the second harmonic, is likely related to the opening/closing of microstructural features such as cracks and grain/grain contacts. In contrast, the second mechanism is related to all other nonlinear parameters (transient softening, hysteresis area and higher order harmonics) and may arise from shearing mechanisms at grain interfaces.

  8. Wave Run-up on A Coaxial Perforated Circular Cylinder

    Institute of Scientific and Technical Information of China (English)

    ZHU Da-tong

    2011-01-01

    This paper describes a plane regular wave interaction with a combined cylinder which consists of a solid inner column and a coaxial perforated outer cylinder. The outer perforated surface is a thin porous cylinder with an annular gap between it and the inner cylinder. The non-linear boundary condition at the perforated wall is a prime focus in the study;energy dissipation at the perforated wall occurs through the resistance to the fluid across the perforated wall. Explicit analytical formulae are presented to calculate the wave run-up on the outer and inner surfaces of the perforated cylinderand the surface of the inner column. The theoretical results of the wave run-up are compared with previous experimental data. Numerical results have also been obtained: when the ratio of the annular gap between the two cylinders to incidentwavelength (b-a)/L≤0.1, the wave run-up on the inner surface of the perforated cylinder and the surface of inner column can partially or completely exceed the incident wave height.

  9. Predicting Nonlinear Behavior and Stress-Strain Relationship of Rectangular Confined Reinforced Concrete Columns with ANSYS

    Directory of Open Access Journals (Sweden)

    A. Tata

    2009-01-01

    Full Text Available This paper presents a nonlinear finite element modeling and analysis of rectangular normal-strength reinforced concrete columns confined with transverse steel under axial compressive loading. In this study, the columns were modeled as discrete elements using ANSYS nonlinear finite element software. Concrete was modeled with 8-noded SOLID65 elements that can translate either in the x-, y-, or z-axis directions from ANSYS element library. Longitudinal and transverse steels were modeled as discrete elements using 3D-LINK8 bar elements available in the ANSYS element library. The nonlinear constitutive law of each material was also implemented in the model. The results indicate that the stress-strain relationships obtained from the analytical model using ANSYS are in good agreement with the experimental data. This has been confirmed with the insignificant difference between the analytical and experimental, i.e. 5.65 and 2.80 percent for the peak stress and the strain at the peak stress, respectively. The comparison shows that the ANSYS nonlinear finite element program is capable of modeling and predicting the actual nonlinear behavior of confined concrete column under axial loading. The actual stress-strain relationship, the strength gain and ductility improvement have also been confirmed to be satisfactorily.

  10. Nonlinear Dynamic Behavior of Functionally Graded Truncated Conical Shell Under Complex Loads

    Science.gov (United States)

    Yang, S. W.; Hao, Y. X.; Zhang, W.; Li, S. B.

    Nonlinear dynamic behaviors of ceramic-metal graded truncated conical shell subjected to complex loads are investigated. The shell is modeled by first-order shear deformation theory. The nonlinear partial differential governing equation in terms of transverse displacements of the FGM truncated conical shell is derived from the Hamilton's principle. Galerkin's method is then utilized to discretize the partial governing equations to a two-degree-of-freedom nonlinear ordinary differential equation. The temperature-dependent materials properties of the constituents are graded in the radial direction in accordance with a power-law distribution. The aerodynamic pressure can be calculated by using the first-order piston theory. The temperature field is assumed to be a steady-state constant-temperature distribution. Bifurcation diagrams, the maximum Lyapunov exponents, wave forms and phase portraits are obtained by numerical simulation to demonstrate the complex nonlinear dynamics response of the FGM truncated conical shell. The influences of the semi-vertex angle, the material gradient index, in-plane and aerodynamic load on the nonlinear dynamics are studied.

  11. Local interaction simulation approach to modelling nonclassical, nonlinear elastic behavior in solids.

    Science.gov (United States)

    Scalerandi, Marco; Agostini, Valentina; Delsanto, Pier Paolo; Van Den Abeele, Koen; Johnson, Paul A

    2003-06-01

    Recent studies show that a broad category of materials share "nonclassical" nonlinear elastic behavior much different from "classical" (Landau-type) nonlinearity. Manifestations of "nonclassical" nonlinearity include stress-strain hysteresis and discrete memory in quasistatic experiments, and specific dependencies of the harmonic amplitudes with respect to the drive amplitude in dynamic wave experiments, which are remarkably different from those predicted by the classical theory. These materials have in common soft "bond" elements, where the elastic nonlinearity originates, contained in hard matter (e.g., a rock sample). The bond system normally comprises a small fraction of the total material volume, and can be localized (e.g., a crack in a solid) or distributed, as in a rock. In this paper a model is presented in which the soft elements are treated as hysteretic or reversible elastic units connected in a one-dimensional lattice to elastic elements (grains), which make up the hard matrix. Calculations are performed in the framework of the local interaction simulation approach (LISA). Experimental observations are well predicted by the model, which is now ready both for basic investigations about the physical origins of nonlinear elasticity and for applications to material damage diagnostics.

  12. Homogenization of the transport behavior of nonlinearly adsorbing pollutants in physically and chemically heterogeneous aquifers

    Science.gov (United States)

    Attinger, Sabine; Dimitrova, Jiva; Kinzelbach, Wolfgang

    2009-05-01

    This paper addresses the question of how spatial variability in the hydraulic and chemical properties of groundwater systems affects the transport and sorption behavior of pollutants at the field scale. In this paper, we limit our investigations on pollutants that adsorb according to an equilibrium controlled nonlinear Freundlich sorption isotherm. The new contribution of this paper is take into account not only spatially variable Freundlich distribution coefficients KS but spatially variable Freundlich nonlinearity parameters p as well. Using a homogenization theory approach, we shortly review the impact of spatially variable hydraulic properties on the transport and extend the theory to spatially variable chemical properties. We show that spatially variable Freundlich exponents cause a very different field scale transport and sorption behavior than spatial variations in the distribution coefficients only since in the first case field scale Freundlich parameters and field scale dispersion coefficients become concentration dependent. In particular, field scale retardation is much larger than small-scale retardation.

  13. Perforated peptic ulcer

    DEFF Research Database (Denmark)

    Søreide, Kjetil; Thorsen, Kenneth; Harrison, Ewen M

    2015-01-01

    Perforated peptic ulcer is a common emergency condition worldwide, with associated mortality rates of up to 30%. A scarcity of high-quality studies about the condition limits the knowledge base for clinical decision making, but a few published randomised trials are available. Although Helicobacte...

  14. Biomineralization in perforate foraminifera

    NARCIS (Netherlands)

    de Nooijer, L.J.; Spero, H.J.; Erez, J.; Bijma, J.; Reichart, G.J.

    2014-01-01

    In this paper, we review the current understanding of biomineralization in perforate foraminifera. Ideas on the mechanisms responsible for the flux of Ca2 + and inorganic carbon from seawater into the test were originally based on light and electron microscopic observations of calcifying

  15. Tricholithobezoar Causing Gastric Perforation

    Directory of Open Access Journals (Sweden)

    Juliana Santos Valenciano

    2012-01-01

    Full Text Available A bezoar is an intraluminal mass formed by the accumulation of undigested material in the gastrointestinal tract. Trichobezoar is a rare condition seen almost exclusively in young women with trichotillomania and trichotillophagia. When not recognized, the trichobezoar continues to grow, which increases the risk of severe complications such as gastric ulceration and even perforation. Formation of a gallstone within the trichobezoar (tricholithobezoar is an event that has not yet been described. We report the case of a 22-year-old woman admitted to the emergency room with signals and symptoms of an epigastric mass and perforative acute abdomen. Radiological study revealed bilateral pneumoperitoneum. Personal history revealed depressive syndrome, trichotillomania and trichophagia. With a diagnosis of visceral perforation, an urgent exploratory laparotomy was performed. This confirmed the diagnosis of gastric perforation due to a large trichobezoar with the formation of a gastrolith that was removed by anterior gastrotomy. Biochemical study of the gastric stone revealed that it was composed of bile salts. There were no complications. The patient was discharged on the 5th postoperative day and was referred for psychiatric treatment.

  16. The Versatile Modiolus Perforator Flap

    DEFF Research Database (Denmark)

    Gunnarsson, Gudjon Leifur; Thomsen, Jorn Bo

    2016-01-01

    BACKGROUND: Perforator flaps are well established, and their usefulness as freestyle island flaps is recognized. The whereabouts of vascular perforators and classification of perforator flaps in the face are a debated subject, despite several anatomical studies showing similar consistency. In our....... The color Doppler ultrasonography study detected a sizeable perforator at the level of the modiolus lateral to the angle of the mouth within a radius of 1 cm. This confirms the anatomical findings of previous authors and indicates that the modiolus perforator is a consistent anatomical finding, and flaps...

  17. Application of constitutive model considering nonlinear unloading behavior for Gen.3 AHSS

    Science.gov (United States)

    Sun, Li; Wagoner, R. H.

    2013-05-01

    Nonlinear unloading behavior has been reported as an important factor for accurate springback prediction. In this study, a newly proposed special component of strain: "Quasi-Plastic-Elastic" ("QPE") strain was utilized to study the springback behavior of Advanced High Strength Steels (AHSS). Several types of steels, including IF steel, DP780, TRIP780, DP980, TWIP980 and QP980 were considered in this research. The results showed that all the tested steels have following behavior: 1) QPE strain is recoverable, like elastic deformation. 2) It dissipates work, like plastic deformation. A 3-D constitutive model considering QPE behavior was implemented in Abaqus/Standard with shell element and applied to draw-bend springback test for Gen. 3 AHSS, QP980. Predictions for springback using the QPE model were more accurate compared with standard elastic-plastic models.

  18. Spontaneous Perforation of Pyometra

    OpenAIRE

    Sharma, Nalini; Singh, Ahanthem Santa; Bhaphiralyne, Wankhar

    2016-01-01

    Pyometra is collection of purulent material which occurs when there is interference with its normal drainage. It is an uncommon condition with incidence of 0.1 to 0.5% of all gynecological patients. Spontaneous rupture of uterus is an extremely rare complication of pyometra. A 65-year-old lady presented with pain abdomen and purulent vaginal discharge. Preoperative diagnosis of pyometra was made by magnetic resonance imaging (MRI). Laparotomy followed by peritoneal lavage and repair of perfor...

  19. Gastric conduit perforation.

    Science.gov (United States)

    Patil, Nilesh; Kaushal, Arvind; Jain, Amit; Saluja, Sundeep Singh; Mishra, Pramod Kumar

    2014-08-16

    As patients with carcinoma of the esophagus live longer, complications associated with the use of a gastric conduit are increasing. Ulcers form in the gastric conduit in 6.6% to 19.4% of patients. There are a few reports of perforation of a gastric conduit in the English literature. Almost all of these were associated with serious complications. We report a patient who developed a tension pneumothorax consequent to spontaneous perforation of an ulcer in the gastric conduit 7 years after the index surgery in a patient with carcinoma of the gastroesophageal junction. He responded well to conservative management. Complications related to a gastric conduit can be because of multiple factors. Periodic endoscopic surveillance of gastric conduits should be considered as these are at a higher risk of ulcer formation than a normal stomach. Long term treatment with proton pump inhibitors may decrease complications. There are no guidelines for the treatment of a perforated gastric conduit ulcer and the management should be individualized.

  20. Nonlinear analysis of pile load-settlement behavior in layered soil

    Institute of Scientific and Technical Information of China (English)

    吕述晖; 王奎华; 张鹏; C. J. LEO3

    2015-01-01

    A simplified approach is presented to analyze the single pile settlement in multilayered soil. First, a fictitious soil−pile model is employed to consider the effect of layered soil beneath pile toe on pile settlement behavior. Two approximation methods are proposed to simplify the nonlinear load transfer function and simulate the nonlinear compression of fictitious soil−pile, respectively. On this basis, an efficient program is developed. The procedures for determining the main parameters of mathematical model are discussed. Comparisons with two well-documented field experimental pile loading tests are conducted to verify the rationality of the present method. Further studies are also made to evaluate the practicability of the proposed approach when a soft substratum exists, and the results suggest that the proposed method can provide a constructive means for assessing the settlement of a single pile for use in engineering design.

  1. Nonlinear coda wave analysis of hysteretic elastic behavior in strongly scattering media

    Science.gov (United States)

    Ouarabi, M. Ait; Boubenider, F.; Gliozzi, A. S.; Scalerandi, M.

    2016-10-01

    Strongly scattering elastic media, such as consolidated granular materials, respond to ultrasonic pulse excitations with a long response signal with peculiar properties. The portion of the signal at late times, termed coda, is due to multiple scattering. It contains information about the elastic properties of the material, and it has been proven to be very sensitive to small variations in the modulus. Here we propose a technique based on a nonlinear analysis of the coda of a signal, which might be applied to quantify the nonlinear elastic response in consolidated granular media exhibiting a hysteretic elastic behavior. The method proposed allows for an intrinsic definition of the reference signal which is normally needed for applying coda-based methods.

  2. Nonlinear behavior of ionically and covalently cross-linked alginate hydrogels

    Science.gov (United States)

    Hashemnejad, Seyedmeysam; Zabet, Mahla; Kundu, Santanu

    2015-03-01

    Gels deform differently under applied load and the deformation behavior is related to their network structures and environmental conditions, specifically, strength and density of crosslinking, polymer concentration, applied load, and temperature. Here, we investigate the mechanical behavior of both ionically and covalent cross-linked alginate hydrogel using large amplitude oscillatory shear (LAOS) and cavitation experiments. Ionically-bonded alginate gels were obtained by using divalent calcium. Alginate volume fraction and alginate to calcium ratio were varied to obtain gels with different mechanical properties. Chemical gels were synthesized using adipic acid dihdrazide (AAD) as a cross-linker. The non-linear rheological parameters are estimated from the stress responses to elucidate the strain softening behavior of these gels. Fracture initiation and propagation mechanism during shear rheology and cavitation experiments will be presented. Our results provide a better understanding on the deformation mechanism of alginate gel under large-deformation.

  3. Structure dynamics with regard to non-linear support behavior; Dynamische Strukturberechnung unter Beruecksichtigung nichtlinearen Lagerverhaltens

    Energy Technology Data Exchange (ETDEWEB)

    Driessen, W. [Technischer Ueberwachungs-Verein Nord e.V., Hamburg (Germany)

    2000-07-01

    Because of modifications to a feed-water line of a power plant structural calculations of the pipework were performed. As a result of a linear (modal) analysis very high restraint forces on the supports were calculated. In order to reduce conservatisms in the calculation the model was optimized with regard to the support stiffnesses and nonlinear behavior of slide bearings, guides and shock absorbers were taken into account. The main result of the non-linear analysis, which was performed by methods of direct-integration, was that nonlinearity yields evident differences in structural frequencies and in energy dissipation (damping) in comparison to the linear analysis. The high restraint forces on the supports became smaller for most of the supports but at some points the forces of the non-linear analysis were even higher. So the conservatism of the linear analysis is not fully valid for the whole structure. The relevance of the non-linear effects in dynamic piping calculations is shown by comparing the calculation result with measurements which were performed on structures in the plant. (orig.) [German] Im Rahmen der Aenderung der Speisewasserleitung einer Kraftwerksanlage wurde die Struktur neu berechnet. Die Analysen mit einem linearen Modell (modal), das ueblicherweise verwendet wird, ergaben hohe Lasten an Halterungen. Zum Abbau von Konservativitaeten wurde eine realistischere Modellierung durch die Beruecksichtigung des nichtlinearen Verhaltens der in der Anlage befindlichen Gleitlager, Fuehrungen und Stossbremsen in der Berechnung vorgenommen. Die Untersuchungen haben ergeben, dass durch die Nichtlinearitaet das Frequenzverhalten der Struktur und die Dissipation von Energie durch Reibvorgaenge wesentlich beeinflusst werden. Des Weiteren ist festzustellen, dass aus linearen Analysen nicht uneingeschraenkt konservative Ergebnisse gewonnen werden. Die Relevanz der Beruecksichtigung des nichtlinearen Lagerverhaltens bei einer dynamischen Strukturberechnung wird

  4. Evaluating Emotional and Biological Sensitivity to Maternal Behavior Among Self-Injuring and Depressed Adolescent Girls Using Nonlinear Dynamics

    DEFF Research Database (Denmark)

    Crowe, Sheila E; Butner, Jonathan E.; Wiltshire, Travis

    2017-01-01

    High sensitivity and reactivity to behaviors of family members characterize several forms of psychopathology, including self-inflicted injury (SII). We examined mother-daughter behavioral and psychophysiological reactivity during a conflict discussion using nonlinear dynamics to assess asymmetrical...... would not evoke mothers’ behavioral or physiological reactivity, and (c) control teens and mothers would be less reactive, with no dynamic associations in either direction. Convergent cross-mapping with dewdrop regression, which identifies directional associations, indicated that mothers’ behaviors...

  5. A high-precision instrument for analyzing nonlinear dynamic behavior of bearing cage

    Science.gov (United States)

    Yang, Z.; Chen, H.; Yu, T.; Li, B.

    2016-08-01

    The high-precision ball bearing is fundamental to the performance of complex mechanical systems. As the speed increases, the cage behavior becomes a key factor in influencing the bearing performance, especially life and reliability. This paper develops a high-precision instrument for analyzing nonlinear dynamic behavior of the bearing cage. The trajectory of the rotational center and non-repetitive run-out (NRRO) of the cage are used to evaluate the instability of cage motion. This instrument applied an aerostatic spindle to support and spin test the bearing to decrease the influence of system error. Then, a high-speed camera is used to capture images when the bearing works at high speeds. A 3D trajectory tracking software tema Motion is used to track the spot which marked the cage surface. Finally, by developing the matlab program, a Lissajous' figure was used to evaluate the nonlinear dynamic behavior of the cage with different speeds. The trajectory of rotational center and NRRO of the cage with various speeds are analyzed. The results can be used to predict the initial failure and optimize cage structural parameters. In addition, the repeatability precision of instrument is also validated. In the future, the motorized spindle will be applied to increase testing speed and image processing algorithms will be developed to analyze the trajectory of the cage.

  6. A high-precision instrument for analyzing nonlinear dynamic behavior of bearing cage.

    Science.gov (United States)

    Yang, Z; Chen, H; Yu, T; Li, B

    2016-08-01

    The high-precision ball bearing is fundamental to the performance of complex mechanical systems. As the speed increases, the cage behavior becomes a key factor in influencing the bearing performance, especially life and reliability. This paper develops a high-precision instrument for analyzing nonlinear dynamic behavior of the bearing cage. The trajectory of the rotational center and non-repetitive run-out (NRRO) of the cage are used to evaluate the instability of cage motion. This instrument applied an aerostatic spindle to support and spin test the bearing to decrease the influence of system error. Then, a high-speed camera is used to capture images when the bearing works at high speeds. A 3D trajectory tracking software tema Motion is used to track the spot which marked the cage surface. Finally, by developing the matlab program, a Lissajous' figure was used to evaluate the nonlinear dynamic behavior of the cage with different speeds. The trajectory of rotational center and NRRO of the cage with various speeds are analyzed. The results can be used to predict the initial failure and optimize cage structural parameters. In addition, the repeatability precision of instrument is also validated. In the future, the motorized spindle will be applied to increase testing speed and image processing algorithms will be developed to analyze the trajectory of the cage.

  7. Duodenal perforation in childhood dermatomyositis

    Energy Technology Data Exchange (ETDEWEB)

    Magill, H.L.; Hixson, S.D.; Whitington, G.; Igarashi, M.; Hannissian, A.

    1984-01-01

    Perforation of the duodenum is an uncommon, but serious complication which may occur in children with dermatomyositis. In this disease vasculitis may involve the bowel to a variable extent and result in radiologic manifestations of intestinal injury ranging from benign pneumatosis intestinalis to signs of bowel perforation. We report two children with dermatomyositis in whom perforation of the second portion of the duodenum occurred. This serious complication should be considered in any child with dermatomyositis when extraluminal gas is suspected on abdominal radiographs.

  8. Premixed Combustion of Coconut Oil on Perforated Burner

    Directory of Open Access Journals (Sweden)

    I.K.G. Wirawan

    2013-10-01

    Full Text Available Coconut oil premixed combustion behavior has been studied experimentally on perforated burner with equivalence ratio (φ varied from very lean until very rich. The results showed that burning of glycerol needs large number of air so that the laminar burning velocity (SL is the highest at very lean mixture and the flame is in the form of individual Bunsen flame on each of the perforated plate hole. As φ is increased the  SL decreases and the secondary Bunsen flame with open tip occurs from φ =0.54 at the downstream of perforated flame. The perforated flame disappears at φ = 0.66 while the secondary Bunsen flame still exist with SL increases following that of hexadecane flame trend and then extinct when the equivalence ratio reaches one or more. Surrounding ambient air intervention makes SL decreases, shifts lower flammability limit into richer mixture, and performs triple and cellular flames. The glycerol diffusion flame radiation burned fatty acids that perform cellular islands on perforated hole.  Without glycerol, laminar flame velocity becomes higher and more stable as perforated flame at higher φ. At rich mixture the Bunsen flame becomes unstable and performs petal cellular around the cone flame front. Keywords: cellular flame; glycerol; perforated flame;secondary Bunsen flame with open tip; triple flame

  9. Perforating disorders of the skin

    Directory of Open Access Journals (Sweden)

    Kalpana Arora

    2013-01-01

    Full Text Available Background: Perforating disorders of the skin, is an often overlooked entity characterized by transepidermal elimination of material from the upper dermis and are classified histopathologically according to the type of epidermal disruption and the nature of the eliminated material. They include Kyrle′s disease, perforating folliculitis, reactive perforating collagenosis, and elastosis perforans serpiginosa. Aim: The aim of this study was to delineate the clinical and histopathological features of perforating disorders of the skin. Materials and Methods: In our study, we reviewed last 2 years skin biopsies received by us. Hematoxylin and eosin sections were re-examined and histochemical stainings (elastic van Gieson and Masson trichrome stains were also used for histopathological evaluation. Results: We reviewed five cases of perforating disorders of skin which included two cases of Kyrle′s disease, two cases of reactive perforating collagenosis and a single case of perforating folliculitis. Two patients had family history of perforating dermatosis in their siblings and three had associated systemic disease. Conclusion: Perforating disorders of the skin should be considered when ulcer with keratotic plugs is found.

  10. Static compressive strength prediction of open-hole structure based on non-linear shear behavior and micro-mechanics

    Science.gov (United States)

    Li, Wangnan; Cai, Hongneng; Li, Chao

    2014-11-01

    This paper deals with the characterization of the strength of the constituents of carbon fiber reinforced plastic laminate (CFRP), and a prediction of the static compressive strength of open-hole structure of polymer composites. The approach combined with non-linear analysis in macro-level and a linear elastic micromechanical failure analysis in microlevel (non-linear MMF) is proposed to improve the prediction accuracy. A face-centered cubic micromechanics model is constructed to analyze the stresses in fiber and matrix in microlevel. Non-interactive failure criteria are proposed to characterize the strength of fiber and matrix. The non-linear shear behavior of the laminate is studied experimentally, and a novel approach of cubic spline interpolation is used to capture significant non-linear shear behavior of laminate. The user-defined material subroutine UMAT for the non-linear share behavior is developed and combined in the mechanics analysis in the macro-level using the Abaqus Python codes. The failure mechanism and static strength of open-hole compressive (OHC) structure of polymer composites is studied based on non-linear MMF. The UTS50/E51 CFRP is used to demonstrate the application of theory of non-linear MMF.

  11. A continuous nonlinear model approach to study the behavior of large signal DC to DC converters

    Science.gov (United States)

    Guinjoan, Francisco

    The study of signal switching DC-DC converters behavior is addressed. Given the fact that the linear methods cannot be used in this case, a nonlinear model was developed. The power stage nonlinear continuous model, which can be applied in both conduction modes (continuous and discontinuous), is obtained from the partition of the characteristic state vector variables in two subsets. This method is applied to the elementary switching cells (buck, boost, and buck-boost) and Cuk converter. It is oriented to the fast numerical simulation by means of general purpose simulation programs. Different results from numerical simulations, confirming the accuracy of the method used, either in an open loop or in a closed loop, are obtained, provided the validity of its domain is respected. The nonlinear model linearization made it possible to obtain equivalent transmittances for the DC-DC converters. Its application to a boost converter operating in the discontinuous condition mode at variable frequency rate enables the comparison of the obtained results with other existing methods and equivalence between the two of them to be easily established. The revision of the initial hypothesis leads to the establishment of a small signal model valid in the high frequency domain and to the results obtained being derived in a more systematic way. A model for switching DC-DC converters is given. Its validity is established, whatever its order and conduction modes, either in an open loop or a closed loop.

  12. Time-Dependent Behavior of Diabase and a Nonlinear Creep Model

    Science.gov (United States)

    Yang, Wendong; Zhang, Qiangyong; Li, Shucai; Wang, Shugang

    2014-07-01

    Triaxial creep tests were performed on diabase specimens from the dam foundation of the Dagangshan hydropower station, and the typical characteristics of creep curves were analyzed. Based on the test results under different stress levels, a new nonlinear visco-elasto-plastic creep model with creep threshold and long-term strength was proposed by connecting an instantaneous elastic Hooke body, a visco-elasto-plastic Schiffman body, and a nonlinear visco-plastic body in series mode. By introducing the nonlinear visco-plastic component, this creep model can describe the typical creep behavior, which includes the primary creep stage, the secondary creep stage, and the tertiary creep stage. Three-dimensional creep equations under constant stress conditions were deduced. The yield approach index (YAI) was used as the criterion for the piecewise creep function to resolve the difficulty in determining the creep threshold value and the long-term strength. The expression of the visco-plastic component was derived in detail and the three-dimensional central difference form was given. An example was used to verify the credibility of the model. The creep parameters were identified, and the calculated curves were in good agreement with the experimental curves, indicating that the model is capable of replicating the physical processes.

  13. COMPARE THE BEHAVIOR FACTOR OF THE ULTIMATE RESISTANCE OF MOMENT FRAME, PLAIN AND PERFORATED STEEL PLATE SHEAR WALLS AND BUCKLING RESTRAINED BRACE AS YIELDING METAL DAMPER

    Directory of Open Access Journals (Sweden)

    Hamid Reza Ashrafi

    2016-03-01

    Full Text Available Steel moment frame systems, steel plate shear walls and also buckling restrained brace (BRB are considered as the most widely used seismic resistant systems of the world. Firstly, in this research, in order to validate the finite element models, the tested sample of steel plate shear walls of 4 floors at the University of Alberta, Canada, and the tested sample of buckling restrained brace at the University of Berkeley California, with the software ABAQUS 6.10-1 were used. Then, the obtained results of the test and analysis have been compared. The confirmed models have been used for the analysis of two-dimensional frame of plain and perforated steel plate shear walls with a regular pattern of positing holes in the screen, buckling restrained brace and moment frame of 4 floors.

  14. [Perforating necrobiosis lipoidica].

    Science.gov (United States)

    Peteiro, C; Zulaica, A; Toribio, J

    1986-01-01

    This is the case history of a woman with a 6 year history of insulin-dependent diabetes mellitus and a 5 year history of tuberous lesions on the dorsal aspect of the metacarpophalangeal joints. Histological examination revealed multiple necrobiotic foci throughout the dermis and subcutaneous tissue, with varying degrees of degeneration, alternating with fibrotic areas. This picture is compatible with lipoid necrobiosis. The existence of various foci of epithelial perforation, manifested clinically by a point hyperkeratosis similar in appearance to blackheads, suggests transfollicular elimination. This would explain the total absence of a pilosebaceous follicles in the lesion.

  15. Nonlinear Socio-Ecological Dynamics and First Principles ofCollective Choice Behavior of ``Homo Socialis"

    Science.gov (United States)

    Sonis, M.

    Socio-ecological dynamics emerged from the field of Mathematical SocialSciences and opened up avenues for re-examination of classical problems of collective behavior in Social and Spatial sciences. The ``engine" of this collective behavior is the subjective mental evaluation of level of utilities in the future, presenting sets of composite socio-economic-temporal-locational advantages. These dynamics present new laws of collective multi-population behavior which are the meso-level counterparts of the utility optimization individual behavior. The central core of the socio-ecological choice dynamics includes the following first principle of the collective choice behavior of ``Homo Socialis" based on the existence of ``collective consciousness": the choice behavior of ``Homo Socialis" is a collective meso-level choice behavior such that the relative changes in choice frequencies depend on the distribution of innovation alternatives between adopters of innovations. The mathematical basis of the Socio-Ecological Dynamics includes two complementary analytical approaches both based on the use of computer modeling as a theoretical and simulation tool. First approach is the ``continuous approach" --- the systems of ordinary and partial differential equations reflecting the continuous time Volterra ecological formalism in a form of antagonistic and/or cooperative collective hyper-games between different sub-sets of choice alternatives. Second approach is the ``discrete approach" --- systems of difference equations presenting a new branch of the non-linear discrete dynamics --- the Discrete Relative m-population/n-innovations Socio-Spatial Dynamics (Dendrinos and Sonis, 1990). The generalization of the Volterra formalism leads further to the meso-level variational principle of collective choice behavior determining the balance between the resulting cumulative social spatio-temporal interactions among the population of adopters susceptible to the choice alternatives and the

  16. Synthesis, structure, linear and third-order nonlinear optical behavior of N-(3-hydroxybenzalidene)4-bromoaniline

    Science.gov (United States)

    Karakaş, Aslı; Ünver, Hüseyin; Elmali, Ayhan

    2008-04-01

    N-(3-Hydroxybenzalidene)4-bromoaniline has been synthesized. Its crystal structure has been determined by X-ray diffraction analysis. To investigate microscopic third-order nonlinear optical (NLO) behavior of the title compound, we have computed both dispersion-free (static) and also frequency-dependent (dynamic) linear polarizabilities ( α) and second hyperpolarizabilities ( γ) at λ = 825-1125 nm and 1050-1600 nm wavelength areas using time-dependent Hartree-Fock (TDHF) method. The one-photon absorption (OPA) characterization has been theoretically obtained by means of configuration interaction (CI) method. The maximum OPA wavelengths are estimated in the UV region to be shorter than 450 nm, showing good optical transparency to the visible light. According to ab-initio calculation results on (hyper)polarizabilities, the synthesized molecule exhibits second hyperpolarizabilities with non-zero values, and it might have microscopic third-order NLO behavior.

  17. Analysis of the Nonlinear Static and Dynamic Behavior of Offshore Structures

    KAUST Repository

    Alfosail, Feras

    2015-07-01

    Understanding static and dynamic nonlinear behavior of pipes and risers is crucial for the design aspects in offshore engineering fields. In this work, we examine two nonlinear problems in offshore engineering field: vortex Induced vibration of straight horizontal pipes, and boundary layer static solution of inclined risers. In the first study, we analyze the effect of the internal velocity of straight horizontal pipe and obtain the vortex induced vibration forces via coupling the pipe equation of motion with the recently modified Van Der Pol oscillator governing the lift coefficient. Our numerical results are obtained for two different pipe configurations: hinged-hinged, and clamped- clamped. The results show that the internal velocity reduces the vibration and the oscillation amplitudes. Also, it is shown that the clamped-clamped pipe configuration offers a wider range of internal velocities before buckling instability occurs. The results also demonstrate the effect of the end condition on the amplitudes of vibration. In the second study, we develop a boundary layer perturbation static solution to govern and simulate the static behavior of inclined risers. In the boundary layer analysis, we take in consideration the effects of the axial stretch, applied tension, and internal velocity. Our numerical simulation results show good agreement with the exact solutions for special cases. In addition, our developed method overcomes the mathematical and numerical limitations of the previous methods used before.

  18. Modeling the macroscopic behavior of two-phase nonlinear composites by infinite-rank laminates

    Science.gov (United States)

    Idiart, Martín I.

    A new approach is proposed for estimating the macroscopic behavior of two-phase nonlinear composites with random, particulate microstructures. The central idea is to model composites by sequentially laminated constructions of infinite rank whose macroscopic behavior can be determined exactly. The resulting estimates incorporate microstructural information up to the two-point correlation functions, and require the solution to a Hamilton-Jacobi equation with the inclusion concentration and the macroscopic fields playing the role of 'time' and 'spatial' variables, respectively. Because they are realizable, by construction, these estimates are guaranteed to be convex, to satisfy all pertinent bounds, to exhibit no duality gap, and to be exact to second order in the heterogeneity contrast. Sample results are provided for two- and three-dimensional power-law composites, and are compared with other homogenization estimates, as well as with numerical simulations available from the literature. The estimates are found to give physically sensible predictions for all the cases considered, even for extreme values of the nonlinearity and heterogeneity contrast. Interestingly, in the case of isotropic porous materials under hydrostatic loadings, the estimates agree exactly with standard Gurson-type models for viscoplastic porous media.

  19. Nonlinear magnetic resonance behavior and reversible adsorbed gas effects from trace ferromagnestism in Y-zeolite

    Energy Technology Data Exchange (ETDEWEB)

    Iton, L.E.

    1977-01-01

    Unusual spin resonance observations made on a sample of rare earth ion-exchanged Y-zeolite have been attributed to the presence of a ferromagnetic impurity, and are qualitatively explained in terms of existing theories on nonlinear behavior in ferromagnetic resonance at high power. The effects included foldover and bistable response below 136 K, due to classical, anisotropy-based nonlinearity; above 136 K, apparent subsidiary absorption--the Suhl instability driven by coupling of low-frequency spin wave modes to the main resonance--predominated. Modification of the surface anisotropy is suggested to account for the complete suppression of the low-temperature effects when the zeolity sample was cooled in air, the high-temperature effects persisting after this cooling but with a loss of orientational anisotropy. Brief room temperature evacuation of the sample was sufficient to regenerate the original effects. Some details of the resonance behavior are very similar to recently published observations from magnetite impurities; those were there attributed to field-induced transitions. The limitations under which a field-dependent Verwey transition could be used to rationalize such observations have been schematically expounded, and the importance of the microwave field again appears to be the dominating factor.

  20. Nonlinear dynamic behaviors of permanent magnet synchronous motors in electric vehicles caused by unbalanced magnetic pull

    Science.gov (United States)

    Xiang, Changle; Liu, Feng; Liu, Hui; Han, Lijin; Zhang, Xun

    2016-06-01

    Unbalanced magnetic pull (UMP) plays a key role in nonlinear dynamic behaviors of permanent magnet synchronous motors (PMSM) in electric vehicles. Based on Jeffcott rotor model, the stiffness characteristics of the rotor system of the PMSM are analyzed and the nonlinear dynamic behaviors influenced by UMP are investigated. In free vibration study, eigenvalue-based stability analysis for multiple equilibrium points is performed which offers an insight in system stiffness. Amplitude modulation effects are discovered of which the mechanism is explained and the period of modulating signal is carried out by phase analysis and averaging method. The analysis indicates that the effects are caused by the interaction of the initial phases of forward and backward whirling motions. In forced vibration study, considering dynamic eccentricity, frequency characteristics revealing softening type are obtained by harmonic balance method, and the stability of periodic solution is investigated by Routh-Hurwitz criterion. The frequency characteristics analysis indicates that the response amplitude is limited in the range between the amplitudes of the two kinds of equilibrium points. In the vicinity of the continuum of equilibrium points, the system hardly provides resistance to bending, and hence external disturbances easily cause loss of stability. It is useful for the design of the PMSM with high stability and low vibration and acoustic noise.

  1. A study on nonlinear behavior of reactor containment structures during ultimate accident condition(I)

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sun Hoon; Kim, Young Jin; Park, Joo Yeon [Youngdong Univ., Yeongdong (Korea, Republic of)] (and others)

    2003-03-15

    In this study, the following scope and contents are established for first year's study of determining ultimate pressure capacity of CANDU-type reactor containment. State-of-arts on the prediction of the ultimate pressure capacity of prestressed concrete reactor containment. Comparative study on structural characteristics and analysis model of CANDU-type reactor containment. State-of-arts on evaluation method of the ultimate pressure capacity of prestressed concrete reactor containment. Enhancement of evaluation method of the ultimate pressure capacity for PWR containment structure. In order to determine a realistic lower bound of a typical reactor containment structural capacity for internal pressure, modelling techniques and analytical investigation to predict its non-linear behavior up to ultimate capacity are required. Especially, the in-depth evaluation of modeling technique and analysis procedure for determining ultimate pressure capacity of CANDU-type reactor containment is required. Therefore, modelling techniques and analytical investigation to predict its non-linear behavior up to ultimate pressure capacity of CANDU-type reactor containment for internal pressure will be suggested in this study.

  2. Influence of transverse reinforcement on perforation resistance of reinforced concrete slabs under hard missile impact

    Energy Technology Data Exchange (ETDEWEB)

    Orbovic, Nebojsa, E-mail: nebojsa.orbovic@cnsc-ccsn.gc.ca; Sagals, Genadijs; Blahoianu, Andrei

    2015-12-15

    better performance of slabs with transverse reinforcement in form of T-headed bars compared to the slabs with conventional stirrups with hooks with regards to perforation capacity under hard missile impact. Non-linear dynamic behavior of reinforced concrete slabs under impact loading by rigid missile was analyzed using the commercial Finite Element (FE) code LS-DYNA. FE blind predictions based on Winfrith concrete material model were compared to the tests on slabs with and without transverse reinforcement. The FE predictions obtained were in general agreement with tests. Two different types of transverse reinforcement were examined (stirrups and T-headed bars) using simplified models. Similar to the tests, the FE predictions show that transverse reinforcement localizes damage induced by missile impact but does not increase the perforation resistance of the concrete slab. FE predictions also showed that T-headed bars perform better than stirrups, providing approximately the same perforation resistance and smaller damaged area comparing with a slab with longitudinal reinforcement only. Additionally, FE modeling was conducted for two different slab thicknesses to assess the effect of the thickness.

  3. Late anastomotic perforation following surgery for gastric neuroendocrine tumor complicated by perforated duodenal ulcer: a case report.

    Science.gov (United States)

    Han, Jun; He, Zhenyu

    2013-03-01

    Neuroendocrine tumors (NETs) are a group of neoplasms that are characterized by the secretion of a variety of hormones and diverse clinical syndromes. NETs are considered to be rare, but the incidence of NETs has increased rapidly in recent years. NETs provide a clinical challenge for physicians because they comprise a heterogeneous group of malignancies with a wide range of morphological, functional, and behavioral characteristics. Subtotal gastrectomy with Billroth II reconstruction is the mainstay of therapy in the management of gastric NETs complicated by perforated duodenal ulcer. Late perforation of anastomotic stoma as a long-term complication has been rarely reported. Here, we report a case of anastomotic perforation 5 years after subtotal gastrectomy due to perforated duodenal ulcer and gastric NETs.

  4. Assessment of Effects of a Delay Block and a Nonlinear Block in Systems with Chaotic Behavior Using Lyapunov Exponents

    Directory of Open Access Journals (Sweden)

    Pablo César Rodríguez Gómez

    2017-05-01

    Full Text Available Context: Because feedback systems are very common and widely used, studies of the structural characteristics under which chaotic behavior is generated have been developed. These can be separated into a nonlinear system and a linear system at least of the third order. Methods such as the descriptive function have been used for analysis. Method: A feedback system is proposed comprising a linear system, a nonlinear system and a delay block, in order to assess his behavior using Lyapunov exponents. It is evaluated with three different linear systems, different delay values and different values for parameters of nonlinear characteristic, aiming to reach chaotic behavior. Results: One hundred experiments were carried out for each of the three linear systems, by changing the value of some parameters, assessing their influence on the dynamics of the system. Contour plots that relate these parameters to the Largest Lyapunov exponent were obtained and analyzed. Conclusions: In spite non-linearity is a condition for the existence of chaos, this does not imply that any nonlinear characteristic generates a chaotic system, it is reflected by the contour plots showing the transitions between chaotic and no chaotic behavior of the feedback system. Language: English

  5. Spontaneous Perforation of Pyometra

    Directory of Open Access Journals (Sweden)

    Begüm Yildizhan

    2006-01-01

    Full Text Available Pyometra is the accumulation of purulent material in the uterine cavity. Its reported incidence is 0.01–0.5% in gynecologic patients; however, as far as elderly patients are concerned, its incidence is 13.6% [3]. The most common cause of pyometra is malignant diseases of genital tract and the consequences of their treatment (radiotherapy. Other causes are benign tumors like leiomyoma, endometrial polyps, senile cervicitis, cervical occlusion after surgery, puerperal infections, and congenital cervical anomalies. Spontaneous rupture of the uterus is an extremely rare complication of pyometra. To our knowledge, only 21 cases of spontaneous perforation of pyometra have been reported in English literature since 1980. This paper reports an additional case of spontaneous uterine rupture.

  6. Familial reactive perforating collagenosis

    Directory of Open Access Journals (Sweden)

    Bhat Yasmeen

    2009-01-01

    Full Text Available Background: Reactive perforating collagenosis (RPC is one of the rare forms of transepidermal elimination in which genetically altered collagen is extruded from the epidermis. This disease usually starts in early childhood as asymptomatic umbilicated papules on extremities, and the lesions become more conspicuous with age. Aims: The objective of our study was to determine the clinico-pathological features of RPC and the response to various treatment modalities. Methods: Ten patients of RPC, belonging to five different families, were studied clinically. Various laboratory investigations were carried out and diagnosis was made by histopathology of the lesions. Patients were given various topical and oral treatments. Results: RPC is familial in most cases without any definite inheritance pattern. It begins in childhood and the lesions are usually recurrent and become profuse and large with age. Systemic diseases have no role in the onset of lesions. Conclusion: Oral and topical retinoids in combination with emollients is the best treatment option.

  7. Nonlinear Dynamic Behavior of a Flexible Structure to Combined External Acoustic and Parametric Excitation

    Directory of Open Access Journals (Sweden)

    Paulo S. Varoto

    2006-01-01

    Full Text Available Flexible structures are frequently subjected to multiple inputs when in the field environment. The accurate determination of the system dynamic response to multiple inputs depends on how much information is available from the excitation sources that act on the system under study. Detailed information include, but are not restricted to appropriate characterization of the excitation sources in terms of their variation in time and in space for the case of distributed loads. Another important aspect related to the excitation sources is how inputs of different nature contribute to the measured dynamic response. A particular and important driving mechanism that can occur in practical situations is the parametric resonance. Another important input that occurs frequently in practice is related to acoustic pressure distributions that is a distributed type of loading. In this paper, detailed theoretical and experimental investigations on the dynamic response of a flexible cantilever beam carrying a tip mass to simultaneously applied external acoustic and parametric excitation signals have been performed. A mathematical model for transverse nonlinear vibration is obtained by employing Lagrange’s equations where important nonlinear effects such as the beam’s curvature and quadratic viscous damping are accounted for in the equation of motion. The beam is driven by two excitation sources, a sinusoidal motion applied to the beam’s fixed end and parallel to its longitudinal axis and a distributed sinusoidal acoustic load applied orthogonally to the beam’s longitudinal axis. The major goal here is to investigate theoretically as well as experimentally the dynamic behavior of the beam-lumped mass system under the action of these two excitation sources. Results from an extensive experimental work show how these two excitation sources interacts for various testing conditions. These experimental results are validated through numerically simulated results

  8. Rett syndrome and gastric perforation.

    Science.gov (United States)

    Shah, Malay B; Bittner, James G; Edwards, Michael A

    2008-04-01

    Rett Syndrome is associated with decreased peristaltic esophageal waves and gastric dysmotility, resulting in swallowing difficulties and gastric dilation. Rarely, gastric necrosis and perforation occur. Our case represents the third reported case of gastric necrosis and perforation associated with Rett Syndrome. A 31-year-old female after 11 hours of intermittent emesis and constant, sharp abdominal pain presented with evidence of multiorgan system failure including hypovolemic shock, metabolic acidosis, coagulopathy, and hepatorenal failure. A chest radiograph revealed intra-abdominal free air necessitating emergent laparotomy. During exploration, a severely dilated, thin-walled stomach with an area of necrosis and gross perforation was noted. Wedge resection of the necrotic tissue and primary closure were performed. Despite aggressive perioperative resuscitation and ventilation support, the patient died 3 hours postoperatively secondary to refractory shock and hypoxemia. Severe gastric dilation can occur with Rett Syndrome and may cause gastric necrosis and perforation. Prolonged elevated gastric pressures can decrease perfusion and may contribute to perforation. Timely decompression via percutaneous endoscopic or surgical gastrostomy could decrease the risk of perforation particularly when significant gastric distention is present. Consideration of gastric necrosis and perforation in patients with Rett Syndrome may lead to earlier intervention and decreased mortality.

  9. Nonlinear dynamic behavior of rubbing rotor under interaction between bending and torsional vibrations

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The nonlinear dynamic behavior of a rubbing rotor system was studied with a mathematical model established with the eccentricity and interaction between bending and torsional vibrations taken into consideration.The nonlinear vibrational response of a rubbing rotor was analyzed using numerical integral,spectroscopic analysis and Poince mapping method,which made it possible to have better understanding of the vibrational characteristics of partial rubbing and complete circular rubbing rotors.The numerical results reveal the response of torsional vibration mainly takes a form of suporchronous motion,and its frequency decreases as the rotational speed increases when partial rubbing occurs,and the response of torsional vibration is synchronous when complete circular rubbing occurs.The comparison of the dynamics of rubbing rotors with and without the interaction between bending and torsional vibrations shows the interaction between bending and torsional vibrations advances the rotational speed,at which the response of bending vibration changes from a synchronous motion into a quasi-periodic motion,and the interaction between bending and torsional vibrations reduces stability of the rubbing rotor.

  10. Thermofluid Behavior of Nonlinear Thermocapillary Solutions in Flow Boiling through Mini⁄Micro Channels

    Science.gov (United States)

    Ono, Naoki; Yoshida, Takahiro; Kaneko, Takahiro; Nishiguchi, Shotaro; Shoji, Masahiro

    The temperature dependency of surface tension of aqueous solutions of some alcohol such as butanol behaves in a nonlinear manner. Namely, the value of surface tension tends to increase, when the solution is heated beyond a temperature. This type of solution is named “nonlinear thermocapillary solution” here. The direction of thermocapillary force in liquid film of the solution on a heated surface acts in the same direction to that of the solutocapillary force. This characteristic will be more marked in small scale systems such as mini⁄micro channels. In this study the liquid behavior of the solution in flow boiling experiments with mini⁄micro tubes was investigated. Butanol aqueous solutions were adopted as test fluids. Pure water and ethanol aqueous solution were also used for comparison. The aim of the study is to observe the liquid motion and to investigate temperature fluctuation in mini⁄micro channels with inner diameter of 1 mm and 0.42 mm. The surface temperature of the tube was measured by using fine K-type thermocouples at the surface of the tubes and the liquid motion was observed by CCD camera system.

  11. Nonlinear Behaviors of Tail Dependence and Cross-Correlation of Financial Time Series Model

    Directory of Open Access Journals (Sweden)

    Wei Deng

    2014-01-01

    Full Text Available Nonlinear behaviors of tail dependence and cross-correlation of financial time series are reproduced and investigated by stochastic voter dynamic system. The voter process is a continuous-time Markov process and is one of the interacting dynamic systems. The tail dependence of return time series for pairs of Chinese stock markets and the proposed financial models is studied by copula analysis, in an attempt to detect and illustrate the existence of relevant correlation relationships. Further, the multifractality of cross-correlations for return series is studied by multifractal detrended cross-correlation analysis, which indicates the analogous cross-correlations and some fractal characters for both actual data and simulative data and provides an intuitive evidence for market inefficiency.

  12. Large time behavior for solutions of nonlinear parabolic problems with sign-changing measure data

    Directory of Open Access Journals (Sweden)

    Francesco Petitta

    2008-09-01

    Full Text Available Let $Omegasubseteq mathbb{R}^N$ a bounded open set, $Ngeq 2$, and let $p>1$; in this paper we study the asymptotic behavior with respect to the time variable $t$ of the entropy solution of nonlinear parabolic problems whose model is $$displaylines{ u_{t}(x,t-Delta_{p} u(x,t=mu quad hbox{in } Omegaimes(0,infty,cr u(x,0=u_{0}(x quad hbox{in } Omega, }$$ where $u_0 in L^{1}(Omega$, and $muin mathcal{M}_{0}(Q$ is a measure with bounded variation over $Q=Omegaimes(0,infty$ which does not charge the sets of zero $p$-capacity; moreover we consider $mu$ that does not depend on time. In particular, we prove that solutions of such problems converge to stationary solutions.

  13. THE NONLINEAR BEHAVIOR OF INTERFACE BETWEEN TWO-PHASE SHEAR FLOW WITH LARGE DENSITY RATIOS

    Institute of Scientific and Technical Information of China (English)

    DONG Yu-hong

    2006-01-01

    The Navier-Stokes equations for the two-dimensional incompressible flow are used to investigate the effects of the Reynolds number and the Weber number on the behavior of interface between liquid-gas shear flow.In the present study, the density ratios are fixed at approximately 100-103.The interface between the two phases is resolved using the level-set approach.The Reynolds number and the Weber number, based on the gas, are selected as 400-10000 and 40-5000, respectively.In the past, simulations reappeared the amplitude of interface growth predicted by viscous Orr-Sommerfeld linear theory, verifying the applicability and accuracy of the numerical method over a wide range of density and viscosity ratios; now, the simulations show that the nonlinear development of ligament elongated structures and resulted in the subsequent breakup of the heavier fluid into drops.

  14. Nonlinear behavior of saturated porous crust under the influence of internal fluid source

    Science.gov (United States)

    Suetnova, Elena; Cherniavski, Vladimir

    2010-05-01

    We consider the effective stress evolution inside high porosity fault zone as a result of local dehydration due to heating. The rock is assumed to be a two-velocity medium; it consists of a deformable porous matrix (with Maxwell's rheology) and a Newtonian liquid that saturates this matrix. Nonlinear behavior of liquid saturated porous media in gravity filed under the influence of internal fluid source is modeled. The elaborated non-isothermal mathematical model is a thermodynamically consistent and closed model. The original scheme was used for computer simulation; the method implies numerical simulation for effective stress, deformation and flux time- space evolution. Deformation spreading through the saturated porous matrix occurs with pressure distortions. Calculations show that the peculiarity of effective stress evolution is dependent not only upon the volume of supplementary fluids, but upon the viscosity and elastic modules of matrix.

  15. Theoretical and Experimental Investigation of the Nonlinear Behavior of an Electrostatically Actuated In-Plane MEMS Arch

    KAUST Repository

    Ramini, Abdallah

    2016-05-02

    We present theoretical and experimental investigation of the nonlinear behavior of a clamped-clamped in-plane MEMS arch when excited by a DC electrostatic load superimposed to an AC harmonic load. Experimentally, a case study of in-plane silicon micromachined arch is examined and its mechanical behavior is measured using optical techniques. An algorithm is developed to extract the various parameters, such as the induced axial force and the initial rise, needed to model the behavior of the arch. A softening spring behavior is observed when the excitation is close to the first resonance frequency due to the quadratic nonlinearity coming from the arch geometry and the electrostatic force. Also, a hardening spring behavior is observed when the excitation is close to the third (second symmetric) resonance frequency due to the cubic nonlinearity coming from mid-plane stretching. Dynamic snap-through behavior is also reported for larger range of electric loads. Theoretically, a multi-mode Galerkin reduced order model is utilized to simulate the arch behavior. General agreement is reported among the theoretical and experimental data.

  16. Perforated midgut diverticulitis: Revisited

    Institute of Scientific and Technical Information of China (English)

    Milan Spasojevic; Jens Marius Naesgaard; Dejan Ignjatovic

    2012-01-01

    AIM:To study and provide data on the evolution of medical procedures and outcomes of patients suffering from perforated midgut diverticulitis.METHODS:Three data sources were used:the Medline and Google search engines were searched for case reports on one or more patients treated for perforated midgut diverticulitis (Meckel's diverticulitis excluded)that were published after 1995.The inclusion criterion was sufficient individual patient data in the article.Both indexed and non-indexed journals were used.Patients treated for perforated midgut diverticulitis at Vestfold Hospital were included in this group.Data on symptoms,laboratory and radiology results,treatment modalities,surgical access,procedures,complications and outcomes were collected.The Norwegian patient registry was searched to find patients operated upon for midgut diverticulitis from 1999 to 2007.The data collected were age,sex,mode of access,surgical procedure performed and number of patients per year.Historical controls were retrieved from an article published in 1995 containing pertinent individual patient data.Statistical analysis was done with SPSS software.RESULTS:Group I:106 patients (48 men) were found.Mean age was 72.2 ± 13.1 years (mean ± SD).Age or sex had no impact on outcomes (P =0.057 and P =0.771,respectively).Preoperative assessment was plain radiography in 53.3% or computed tomography (CT)in 76.1%.Correct diagnosis was made in 77.1% with CT,5.6% without (P =0.001).Duration of symptoms before hospitalization was 3.6 d (range:1-35 d),but longer duration was not associated with poor outcome (P =0.748).Eighty-six point eight percent of patients underwent surgery,92.4% of these through open access where 90.1% had bowel resection.Complications occurred in 19.2% of patients and 16.3% underwent reoperation.Distance from perforation to Treitz ligament was 41.7 ± 28.1 cm.At surgery,no peritonitis was found in 29.7% of patients,local peritonitis in 47.5%,and diffuse

  17. Spontaneous Perforation of Rectosigmoid Colon

    Directory of Open Access Journals (Sweden)

    Farhad Haj Sheikholeslami

    2010-12-01

    Full Text Available Spontaneous perforation of the sigmoid colon or rectom is definedas a sudden perforation of the colon in the absence of diseasessuch as tumors, diverticulosis or external injury. It is avery rare finding, and if neglected, results in severe peritonitisand high mortality. The causes of this rare condition are numerous,and in this case it might be due to the chronic constipationinduced by an anticholinergic antipsychotic.Iran J Med Sci 2010; 35(4: 339-341.

  18. Helicobacter pylori in gastroduodenal perforation

    Directory of Open Access Journals (Sweden)

    Bharat B Dogra

    2014-01-01

    Full Text Available Background:peptic ulcers were earlier believed to be caused by dietary factors, gastric acid, and stress. However, in 1983, Warren and Marshall identified the correlation between Helicobacter pylori (H. pylori and peptic ulcers. It is now well established that most of the peptic ulcers occur as a result of H. pylori infection. But the co-relation between perforated peptic ulcer and H. pylori infection is not yet fully established. Aims and objectives : to study the prevalence of H. pylori infection in patients with perforated peptic ulcer. Materials and methods: this was a prospective study carried out in all cases of perforated peptic ulcer reporting in surgical wards of a medical college during 2008-2010. A total of 50 cases, presenting as acute perforation of duodenum and stomach during this period, formed the study group. After resuscitation, all the cases were subjected to emergency exploratory laparotomy. The exact site of perforation was identified, biopsy was taken from the ulcer margin from 2-3 sites and the tissue was sent for H. pylori culture and histopathological examination. Simple closure of perforation, omentoplasty, thorough peritoneal lavage and drainage was carried out. Results: out of the 50 cases of perforated peptic ulcer, 38 happened to be males, and only 12 were females. The age of the patients ranged from 20 to 70 years. All the patients underwent only emergency laparotomy. As many as 46 cases (92% turned out to be positive for H. pylori and only four cases (8% were negative for this infection. Postoperatively, patients who were found to be positive for H. pylori were put on anti-H. pylori treatment. Conclusion: there was a high prevalence of H. pylori infection in patients with perforated gastroduodenal ulcers.

  19. Unusual presentation of gallbladder perforation

    OpenAIRE

    Jayasinghe, G.; Adam, J.; Abdul-Aal, Y.

    2016-01-01

    Introduction: Gall bladder perforation is associated with high mortality rates and therefore must be recognised and managed promptly. We present an unusual presentation of spontaneous gall bladder perforation. Case presentation: An elderly lady with multiple medical co-morbidities was admitted with sepsis following a fall. Initial assessment lead to a diagnosis of pneumonia, however a rapidly expanding right flank mass was incidentally noted during routine nursing care. Imaging studies wer...

  20. The behavior of steady quasisolitons near the limit cases of third-order nonlinear Schrödinger equation

    DEFF Research Database (Denmark)

    Karpman, V.I.; Shagalov, A.G.; Juul Rasmussen, J.

    2002-01-01

    The behavior of steady quasisoliton solutions to the extended third-order nonlinear Schrodinger (NLS) equation is studied in two cases: (i) when the coefficients in the equation approach the Hirota conditions, and (ii) near the limit of the regular NLS equation. (C) 2002 Published by Elsevier...

  1. Investigation of the nonlinear seismic behavior of knee braced frames using the incremental dynamic analysis method

    Science.gov (United States)

    Sheidaii, Mohammad Reza; TahamouliRoudsari, Mehrzad; Gordini, Mehrdad

    2016-06-01

    In knee braced frames, the braces are attached to the knee element rather than the intersection of beams and columns. This bracing system is widely used and preferred over the other commonly used systems for reasons such as having lateral stiffness while having adequate ductility, damage concentration on the second degree convenience of repairing and replacing of these elements after Earthquake. The lateral stiffness of this system is supplied by the bracing member and the ductility of the frame attached to the knee length is supplied through the bending or shear yield of the knee member. In this paper, the nonlinear seismic behavior of knee braced frame systems has been investigated using incremental dynamic analysis (IDA) and the effects of the number of stories in a building, length and the moment of inertia of the knee member on the seismic behavior, elastic stiffness, ductility and the probability of failure of these systems has been determined. In the incremental dynamic analysis, after plotting the IDA diagrams of the accelerograms, the collapse diagrams in the limit states are determined. These diagrams yield that for a constant knee length with reduced moment of inertia, the probability of collapse in limit states heightens and also for a constant knee moment of inertia with increasing length, the probability of collapse in limit states increases.

  2. Effects of stress and physical ageing on nonlinear creep behavior of poly(methyl methacrylate)

    Institute of Scientific and Technical Information of China (English)

    赵荣国; 陈朝中; 李其抚; 罗文波

    2008-01-01

    The effects of stress,ageing time and ageing temperature on creep behavior of poly(methyl methacrylate) were studied.After annealing above its glass transition temperature for a period of time to eliminate the stress and thermal history,the specimens were quenched and aged at various ageing temperatures for different ageing time,and then the short-term creep tests under different stress levels were carried out at room temperature.The creep strains were modeled by means of time-ageing time equivalence and time-stress equivalence,and the master creep curves were constructed via ageing time shift factors and stress shift factors.The results indicate that the creep rate increases with stress,while decreases with ageing time,and the ageing temperature history obviously affects the creep rate.For linear viscoelastic material,the ageing shift rate is independent on imposed stress,while for nonlinear viscoelastic material,the ageing shift rate decreases with increasing stress.The unified master creep curve up to 540 d at reference state was constructed by shifting the creep curves horizontally along the logarithmic time axis to overlap each other.It is demonstrated that the time-stress equivalence,united with the time-ageing time equivalence,provides an effective accelerated characterization technique in the laboratory to evaluate the long-term creep behavior of physical ageing polymers.

  3. Modelling nonlinear behavior of labor force participation rate by STAR: An application for Turkey

    Directory of Open Access Journals (Sweden)

    Sibel Cengiz

    2014-04-01

    Full Text Available The aim of this paper is to contribute to the understanding of the behavior of participation rates in terms of gender differences. We employed smooth autoregressive transition models for the quarterly Turkish labor force participation rates (LFPR data between 2000: Q1 - 2011: Q4 to present an asymmetric participation behavior. The smoothness parameter indicates a gradual transition from low to high regimes. It is higher for female workers compared to the male workers. Participation rates diminish during a recession but they increase smoothly during the periods of expansion. The estimation results of Enders et al. (1998 also verified the asymmetry and nonlinearity in participation rates. During periods of economic expansion, they are higher than the threshold but the low regime indicator function takes the value zero. The results of the paper have economic implications for policy makers. Due to the discouraged worker and added worker effects, LFPR should be observed with the unemployment rates while evaluating the tightness of the labor market.

  4. Analysis and classification of collective behavior using generative modeling and nonlinear manifold learning.

    Science.gov (United States)

    Butail, Sachit; Bollt, Erik M; Porfiri, Maurizio

    2013-11-07

    In this paper, we build a framework for the analysis and classification of collective behavior using methods from generative modeling and nonlinear manifold learning. We represent an animal group with a set of finite-sized particles and vary known features of the group structure and motion via a class of generative models to position each particle on a two-dimensional plane. Particle positions are then mapped onto training images that are processed to emphasize the features of interest and match attainable far-field videos of real animal groups. The training images serve as templates of recognizable patterns of collective behavior and are compactly represented in a low-dimensional space called embedding manifold. Two mappings from the manifold are derived: the manifold-to-image mapping serves to reconstruct new and unseen images of the group and the manifold-to-feature mapping allows frame-by-frame classification of raw video. We validate the combined framework on datasets of growing level of complexity. Specifically, we classify artificial images from the generative model, interacting self-propelled particle model, and raw overhead videos of schooling fish obtained from the literature. © 2013 Elsevier Ltd. All rights reserved.

  5. Solution behaviors in coupled Schrödinger equations with full-modulated nonlinearities

    Science.gov (United States)

    Pınar, Zehra; Deliktaş, Ekin

    2017-02-01

    The nonlinear partial differential equations have an important role in real life problems. To obtain the exact solutions of the nonlinear partial differential equations, a number of approximate methods are known in the literature. In this work, a time- space modulated nonlinearities of coupled Schrödinger equations are considered. We provide a large class of Jacobi-elliptic solutions via the auxiliary equation method with sixth order nonlinearity and the Chebyshev approximation.

  6. The Approximate Analysis of Nonlinear Behavior of Structure under Harmonic Loading

    DEFF Research Database (Denmark)

    Bayat, M.; Shahidi, M.; Barari, Amin;

    2010-01-01

    to the scientists in the field. Studying on nonlinear dynamics highlights the fact that essentially all dynamic systems encountered in the real world are nonlinear, meaning that their description as differential equations contains nonlinear terms. Such nonlinearities appear in different ways, such as through...... analytically. In the end, the obtained results are compared with numerical ones and shown in graphs and in tables; analytical solutions are in good agreement with those of the numerical method....

  7. Premixed Combustion of Coconut Oil on Perforated Burner

    OpenAIRE

    I.K.G. Wirawan; I. N. G. Wardana; Rudy Soenoko; Slamet Wahyudi

    2013-01-01

    Coconut oil premixed combustion behavior has been studied experimentally on perforated burner with equivalence ratio (φ) varied from very lean until very rich. The results showed that burning of glycerol needs large number of air so that the laminar burning velocity (SL) is the highest at very lean mixture and the flame is in the form of individual Bunsen flame on each of the perforated plate hole. As φ is increased the  SL decreases and the secondary Bunsen flame with open tip occurs from φ ...

  8. CLINICAL STUDY OF DUODENAL PERFORATION

    Directory of Open Access Journals (Sweden)

    Sambasiva Rao

    2016-04-01

    Full Text Available BACKGROUND The duodenal injury can pose a formidable challenge to the surgeon and failure to manage it properly may have devastating results. Over the centuries, there was little to offer the patient of acute abdomen beyond cupping, purgation and enemas, all of which did more harm than good. It was not until 1884 that Mikulicz made an attempt to repair a perforation. Recent statistics indicate roughly 10% of population develop gastric or duodenal ulcer in life time. Roughly 1-3% of population above the age of 20 years have some degree of peptic ulcer activity during any annual period. A detailed history with regards to the signs and symptoms of the patient, a meticulous examination, radiological and biochemical investigations help to arrive at a correct preoperative diagnosis. In this study, a sincere effort has been put to understand the demographic patterns, to understand the underlying aetiology and to understand the effectiveness of the standard methods of investigation and treatment in use today. METHODS This is a 24 months prospective study i.e., from September 2011 to September 2013 carried out at Dr. Pinnamaneni Siddhartha Institute of Medical Sciences & Research Foundation. The study included the patients presenting to Dr. Pinnamaneni Siddhartha Institute of Medical Sciences & Research Foundation to emergency ward with signs and symptoms of hollow viscus perforation. The sample size included 30 cases of duodenal perforation. RESULTS Duodenal ulcer perforation commonly occurs in the age group of 30-60 years, but it can occur in any age group. Majority of the patients were male. Smoking and alcohol consumption were risk factors in most cases (53.3% for the causation of duodenal ulcer perforation. Sudden onset of abdominal pain, situated at epigastrium and right hypochondrium was a constant symptom (100%. Vomiting, constipation and fever were not so common. CONCLUSION The emergency surgical management for perforated duodenal ulcer is by

  9. Uncertainty of the Numerical Solution of a Nonlinear System's Long-term Behavior and Global Convergence of the Numerical Pattern

    Institute of Scientific and Technical Information of China (English)

    胡淑娟; 丑纪范

    2004-01-01

    The computational uncertainty principle in nonlinear ordinary differential equations makes the numerical solution of the long-term behavior of nonlinear atmospheric equations have no meaning. The main reason is that, in the error analysis theory of present-day computational mathematics, the non-linear process between truncation error and rounding erroris treated as a linear operation. In this paper, based on the operator equations of large-scale atmospheric movement, the above limitation is overcome by using the notion of cell mapping. Through studying the global asymptotic characteristics of the numerical pattern of the large-scale atmospheric equations, the definitions of the global convergence and an appropriate discrete algorithm of the numerical pattern are put forward. Three determinant theorems about the global convergence of the numerical pattern are presented, which provide the theoretical basis for constructing the globally convergent numerical pattern. Further, it is pointed out that only a globally convergent numerical pattern can improve the veracity of climatic prediction.

  10. Synthesis, characterization and femtosecond nonlinear saturable absorption behavior of copper phthalocyanine nanocrystals doped-PMMA polymer thin films

    Science.gov (United States)

    Zongo, S.; Dhlamini, M. S.; Neethling, P. H.; Yao, A.; Maaza, M.; Sahraoui, B.

    2015-12-01

    In this work, we report the femtosecond nonlinear saturable absorption response of synthesized copper phthalocyanine nanocrystals (CPc-NCs)-doped PMMA polymer thin films. The samples were initially characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), UV-Vis and scanning electron microscopy (SEM) techniques. The crystalline phase and morphological analysis revealed nanocrystals of monoclinic structure with an average crystallite size between 31.38 nm and 42.5 nm. The femtosecond Z-scan study at 800 nm central wavelength indicated a saturable absorption behavior of which the mechanism is closely related to the surface plasmon resonance (SPR) of the particles. This nonlinear effect could potentially make the CPc-NCs useful in nonlinear optical devices.

  11. The Nonlinear Behavior of Vibrational Conveyers with Single-Mass Crank-and-Rod Exciters

    Directory of Open Access Journals (Sweden)

    G. Füsun Alışverişçi

    2012-01-01

    Full Text Available The single-mass, crank-and-rod exciters vibrational conveyers have a trough supported on elastic stands which are rigidly fastened to the trough and a supporting frame. The trough is oscillated by a common crank drive. This vibration causes the load to move forward and upward. The moving loads jump periodically and move forward with relatively small vibration. The movement is strictly related to vibrational parameters. This is applicable in laboratory conditions in the industry which accommodate a few grams of loads, up to those that accommodate tons of loading capacity. In this study I explore the transitional behavior across resonance, during the starting of a single degree of freedom vibratory system excited by crank-and-rod. A loaded vibratory conveyor is more safe to start than an empty one. Vibrational conveyers with cubic nonlinear spring and ideal vibration exciter have been analyzed analytically for primary and secondary resonance by the Method of Multiple Scales, and numerically. The approximate analytical results obtained in this study have been compared with the numerical results and have been found to be well matched.

  12. Geometrically nonlinear deformation and the emergent behavior of polarons in soft matter.

    Science.gov (United States)

    Li, Xiaobao; Liu, Liping; Sharma, Pradeep

    2015-11-07

    Mechanical strain can alter the electronic structure of both bulk semiconductors as well as nanostructures such as quantum dots. This fact has been extensively researched and exploited for tailoring electronic properties. The strain mediated interaction between the charge carriers and the lattice is interpreted through the so-called deformation potential. In the case of soft materials or nanostructures, such as DNA, the deformation potential leads to the formation of polarons which largely determine the electronic characteristics of DNA and similar polymer entities. In addition, polarons are also speculated to be responsible for the mechanism of quantum actuation in carbon nanotubes. The deformation potential is usually taken to be a linear function of the lattice deformation (U ∼ αε) where α is the deformation potential "constant" that determines the coupling strength and ε is the mechanical strain. In this letter, by carefully accounting for nonlinear geometric deformation that has been hitherto ignored so far in this context, we show that the deformation potential constant is renormalized in a non-trivial manner and is hardly a constant. It varies spatially within the material and with the size of the material. This effect, while negligible for hard materials, is found to be important for soft materials and critically impacts the interpretation of quantities such as polaron size, binding energy, and accordingly, electronic behavior.

  13. Nonlinear seismic behavior of a CANDU containment building subjected to near-field ground motions

    Energy Technology Data Exchange (ETDEWEB)

    Choi, In Kil; Ahn, Seong Moon; Choun, Young Sun; Seo, Jeong Moon [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    2004-07-01

    The standard response spectrum proposed by US NRC has been used as a design earthquake for the design of Korean nuclear power plant structures. A survey on some of the Quaternary fault segments near Korean nuclear power plants is ongoing. It is likely that these faults will be identified as active ones. If the faults are confirmed as active ones, it will be necessary to reevaluate the seismic safety of the nuclear power plants located near the fault. Near-fault ground motions are the ground motions that occur near an earthquake fault. In general, the near-fault ground motion records exhibit a distinctive long period pulse like time history with very high peak velocities. These features are induced by the slip of the earthquake fault. Near-fault ground motions, which have caused much of the damage in recent major earthquakes, can be characterized by a pulse-like motion that exposes the structure to a high input energy at the beginning of the motion. In this study, nonlinear dynamic time-history analyses were performed to investigate the seismic behavior of a CANDU containment structure subjected to various earthquake ground motions including the near-field ground motions.

  14. Nonlinear conductive properties and scaling behavior of conductive particle filled high-density polyethylene composites

    Institute of Scientific and Technical Information of China (English)

    ZHENG Qiang; SHEN Lie; LI Wenchun; SONG Yihu; YI Xiaosu

    2005-01-01

    The blends prepared by incorporation of carbon black (CB) or graphite powder (GP) inHto high-density polyethylene (HDPE) matrix have been novel and extensively applied polymeric positive temperature coefficient (PTC) composites. A phenomenological model was proposed on the basis of the GEM equation and the dilution effect of filler volume fraction due to the thermal volume expansion of the polymer matrix. Accordingly, the contribution of the thermal expansion of the matrix to the jump-like PTC transition of the composites was quantitatively estimated and a mechanical explanation was given. It was proved that the contribution of the volume expansion to PTC effect decreased for HDPE/CB composites crosslinked through electron-beam irradiation. Furthermore, the influences of the filler content, temperature and crosslinking on the self-heating behavior as well as the nonlinear conduction characteristics at electrical-thermal equilibrium state were examined. Based on the electric-field and initial resistivity dependence of the self-heating temperature and resistance dependence of the critical field, the mechanisms of the self-heating of the polymeric PTC materials were evaluated. The intrinsic relations between macroscopic electrical properties and microscopic percolation network at electrical-thermal equilibrium state were discussed according to the scaling relationship between the self-heating critical parameter and the conductivity of materials.

  15. On the nonlinear axisymmetric dynamic buckling behavior of clamped functionally graded spherical caps

    Science.gov (United States)

    Prakash, T.; Sundararajan, N.; Ganapathi, M.

    2007-01-01

    Here, the dynamic thermal buckling behavior of functionally graded spherical caps is studied considering geometric nonlinearity based on von Karman's assumptions. The formulation is based on first-order shear deformation theory and it includes the in-plane and rotary inertia effects. The material properties are graded in the thickness direction according to the power-law distribution in terms of volume fractions of the material constituents. The effective material properties are evaluated using homogenization method. The governing equations obtained using finite element approach are solved employing the Newmark's integration technique coupled with a modified Newton-Raphson iteration scheme. The pressure load corresponding to a sudden jump in the maximum average displacement in the time history of the shell structure is taken as the dynamic buckling load. The present model is validated against the available isotropic case. A detailed numerical study is carried out to highlight the influences of shell geometries, power law index of functional graded material and boundary conditions on the dynamic buckling load of shallow spherical shells.

  16. Controlling the dynamical behavior of nonlinear fiber ring resonators with balanced loss and gain

    CERN Document Server

    Deka, Jyoti P; Sarma, Amarendra K

    2015-01-01

    We show the possibility of controlling the dynamical behavior of a single fiber ring (SFR) resonator system with the fiber being an amplified (gain) channel and the ring being attenuated (loss) nonlinear dielectric medium. The system considered here is a simple alteration in the basic building block of the parity time (PT) symmetric synthetic coupler structures reported in A. Regensburger et al., Nature 488, 167 (2012). We find that this result in a dynamically controllable algorithm for the chaotic dynamics inherent in the system. We have also shown the dependence of the period doubling point upon the input amplitude, emphasizing on the dynamical aspects of our system. Moreover, the fact that the resonator essentially plays the role of a damped harmonic oscillator has been elucidated with the non-zero intensity inside the resonator due to constant influx of input light. This study may be a step forward to further investigations in regard to the inter-connectivity between the PT symmetry and chaos along with ...

  17. Posterior repair with perforated porcine dermal graft

    Directory of Open Access Journals (Sweden)

    G. Bernard Taylor

    2008-02-01

    Full Text Available OBJECTIVE: To compare postoperative vaginal incision separation and healing in patients undergoing posterior repair with perforated porcine dermal grafts with those that received grafts without perforations. Secondarily, the tensile properties of the perforated and non-perforated grafts were measured and compared. MATERIALS AND METHODS: This was a non-randomized retrospective cohort analysis of women with stage II or greater rectoceles who underwent posterior repair with perforated and non-perforated porcine dermal grafts (PelvicolTM CR Bard Covington, GA USA. The incidence of postoperative vaginal incision separation (dehiscence was compared. A secondary analysis to assess graft tensile strength, suture pull out strength, and flexibility after perforation was performed using standard test method TM 0133 and ASTM bending and resistance protocols. RESULTS: Seventeen percent of patients (21/127 who received grafts without perforations developed vaginal incision dehiscence compared to 7% (5/71 of patients who received perforated grafts (p = 0.078. Four patients with vaginal incision dehiscence with non-perforated grafts required surgical revision to facilitate healing. Neither tensile strength or suture pull out strength were significantly different between perforated and non-perforated grafts (p = 0.81, p = 0.29, respectively. There was no difference in the flexibility of the two grafts (p = 0.20. CONCLUSION: Perforated porcine dermal grafts retain their tensile properties and are associated with fewer vaginal incision dehiscences.

  18. Numerical Method for Wave Forces Acting on Partially Perforated Caisson

    Institute of Scientific and Technical Information of China (English)

    姜峰; 唐晓成; 金钊; 张莉; 陈洪洲

    2015-01-01

    The perforated caisson is widely applied to practical engineering because of its great advantages in effectively wave energy consumption and cost reduction. The attentions of many scientists were paid to the fluid–structure interaction between wave and perforated caisson studies, but until now, most concerns have been put on theoretical analysis and experimental model set up. In this paper, interaction between the wave and the partial perforated caisson in a 2D numerical wave flume is investigated by means of the renewed SPH algorithm, and the mathematical equations are in the form of SPH numerical approximation based on Navier–Stokes equations. The validity of the SPH mathematical method is examined and the simulated results are compared with the results of theoretical models, meanwhile the complex hydrodynamic characteristics when the water particles flow in or out of a wave absorbing chamber are analyzed and the wave pressure distribution of the perforated caisson is also addressed here. The relationship between the ratio of total horizontal force acting on caisson under regular waves and its influence factors is examined. The data show that the numerical calculation of the ratio of total horizontal force meets the empirical regression equation very well. The simulations of SPH about the wave nonlinearity and breaking are briefly depicted in the paper, suggesting that the advantages and great potentiality of the SPH method is significant compared with traditional methods.

  19. Numerical method for wave forces acting on partially perforated caisson

    Science.gov (United States)

    Jiang, Feng; Tang, Xiao-cheng; Jin, Zhao; Zhang, Li; Chen, Hong-zhou

    2015-04-01

    The perforated caisson is widely applied to practical engineering because of its great advantages in effectively wave energy consumption and cost reduction. The attentions of many scientists were paid to the fluid-structure interaction between wave and perforated caisson studies, but until now, most concerns have been put on theoretical analysis and experimental model set up. In this paper, interaction between the wave and the partial perforated caisson in a 2D numerical wave flume is investigated by means of the renewed SPH algorithm, and the mathematical equations are in the form of SPH numerical approximation based on Navier-Stokes equations. The validity of the SPH mathematical method is examined and the simulated results are compared with the results of theoretical models, meanwhile the complex hydrodynamic characteristics when the water particles flow in or out of a wave absorbing chamber are analyzed and the wave pressure distribution of the perforated caisson is also addressed here. The relationship between the ratio of total horizontal force acting on caisson under regular waves and its influence factors is examined. The data show that the numerical calculation of the ratio of total horizontal force meets the empirical regression equation very well. The simulations of SPH about the wave nonlinearity and breaking are briefly depicted in the paper, suggesting that the advantages and great potentiality of the SPH method is significant compared with traditional methods.

  20. Influence of surface roughness on nonlinear flow behaviors in 3D self-affine rough fractures: Lattice Boltzmann simulations

    Science.gov (United States)

    Wang, Min; Chen, Yi-Feng; Ma, Guo-Wei; Zhou, Jia-Qing; Zhou, Chuang-Bing

    2016-10-01

    This study investigates the impacts of surface roughness on the nonlinear fluid flow through three-dimensional (3D) self-affine rock fractures, whose original surface roughness is decomposed into primary roughness (i.e. the large-scale waviness of the fracture morphology) and secondary roughness (i.e. the small-scale unevenness) with a wavelet analysis technique. A 3D Lattice Boltzmann method (LBM) is adopted to predict the flow physics in rock fractures numerically created with and without consideration of the secondary roughness, respectively. The simulation results show that the primary roughness mostly controls the pressure distribution and fracture flow paths at a large scale, whereas the secondary roughness determines the nonlinear properties of the fluid flow at a local scale. As the pressure gradient increases, the secondary roughness enhances the local complexity of velocity distribution by generating and expanding the eddy flow and back flow regions in the vicinity of asperities. It was found that the Forchheimer's law characterizes well the nonlinear flow behavior in fractures of varying roughness. The inertial effects induced by the primary roughness differ only marginally in fractures with the roughness exponent varying from 0.5 to 0.8, and it is the secondary roughness that significantly enhances the nonlinear flow and leads to earlier onset of nonlinearity. Further examined were the effects of surface roughness on the transmissivity, hydraulic aperture and the tortuosity of flow paths, demonstrating again the dominant role of the secondary roughness, especially for the apparent transmissivity and the equivalent hydraulic aperture at high pressure gradient or high Reynolds number. The results may enhance our understanding of the role of surface roughness in the nonlinear flow behaviors in natural rock fractures.

  1. Laparoscopic treatment of perforated appendicitis

    Science.gov (United States)

    Lin, Heng-Fu; Lai, Hong-Shiee; Lai, I-Rue

    2014-01-01

    The use of laparoscopy has been established in improving perioperative and postoperative outcomes for patients with simple appendicitis. Laparoscopic appendectomy is associated with less wound pain, less wound infection, a shorter hospital stay, and faster overall recovery when compared to the open appendectomy for uncomplicated cases. In the past two decades, the use of laparoscopy for the treatment of perforated appendicitis to take the advantages of minimally invasiveness has increased. This article reviewed the prevalence, approaches, safety disclaimers, perioperative and postoperative outcomes of the laparoscopic appendectomy in the treatment of patients with perforated appendicitis. Special issues including the conversion, interval appendectomy, laparoscopic approach for elderly or obese patient are also discussed to define the role of laparoscopic treatment for patients with perforated appendicitis. PMID:25339821

  2. Long Time Behavior for a System of Differential Equations with Non-Lipschitzian Nonlinearities

    Directory of Open Access Journals (Sweden)

    Nasser-Eddine Tatar

    2014-01-01

    Full Text Available We consider a general system of nonlinear ordinary differential equations of first order. The nonlinearities involve distributed delays in addition to the states. In turn, the distributed delays involve nonlinear functions of the different variables and states. An explicit bound for solutions is obtained under some rather reasonable conditions. Several special cases of this system may be found in neural network theory. As a direct application of our result it is shown how to obtain global existence and, more importantly, convergence to zero at an exponential rate in a certain norm. All these nonlinearities (including the activation functions may be non-Lipschitz and unbounded.

  3. Modulation of nonlinear resistive switching behavior of a TaOx-based resistive device through interface engineering

    Science.gov (United States)

    Wang, Zongwei; Kang, Jian; Yu, Zhizhen; Fang, Yichen; Ling, Yaotian; Cai, Yimao; Huang, Ru; Wang, Yangyuan

    2017-02-01

    A resistive switching device with inherent nonlinear characteristics through a delicately engineered interfacial layer is an ideal component to be integrated into passive crossbar arrays for the suppression of sneaking current, especially in ultra-dense 3D integration. In this paper, we demonstrated a TaOx-based bipolar resistive switching device with a nearly symmetrical bi-directional nonlinear feature through interface engineering. This was accomplished by introducing an ultra-thin interfacial layer (SiO2-x) with unique features, including a large band gap and a certain level of negative heat of oxide formation between the top electrode (TiN) and resistive layer (TaOx). The devices exhibit excellent nonlinear property under both positive and negative bias. Modulation of the inherent nonlinearity as well as the resistive switching mechanism are comprehensively studied by scrutinizing the results of the experimental control groups and the extensive characterizations including detailed compositional analysis, which suggests that the underlying mechanism of the nonlinear behavior is associatively governed by the serially connected metallic conductive filament and Flower-Nordheim tunneling barrier formed by the SiO2-x interface layer. The proposed device in this work has great potential to be implemented in future massive storage memory applications of high-density selector-free crossbar structure.

  4. Triple gastric peptic ulcer perforation.

    Science.gov (United States)

    Radojkovic, Milan; Mihajlovic, Suncica; Stojanovic, Miroslav; Stanojevic, Goran; Damnjanovic, Zoran

    2016-03-01

    Patients with advanced or metastatic cancer have compromised nutritional, metabolic, and immune conditions. Nevertheless, little is known about gastroduodenal perforation in cancer patients. Described in the present report is the case of a 41-year old woman with stage IV recurrent laryngeal cancer, who used homeopathic anticancer therapy and who had triple peptic ulcer perforation (PUP) that required surgical repair. Triple gastric PUP is a rare complication. Self-administration of homeopathic anticancer medication should be strongly discouraged when evidence-based data regarding efficacy and toxicity is lacking.

  5. Perforating Disseminated Necrobiosis Lipoidica Diabeticorum

    Directory of Open Access Journals (Sweden)

    Paula Lozanova

    2013-01-01

    Full Text Available Perforating necrobiosis lipoidica is a very rare clinical variant which consists of degeneration and transepidermal elimination of the collagen with few cases reported in the literature. In two-thirds of the patients it associates with diabetes, with no relation with the glucose control. We present a 42-year-old female patient with a 7-year history of diabetes on insulin therapy, referred to our clinic with a 3-year history of multiple asymptomatic firm plaques disseminated on the upper and lower extremities. The clinical and histological findings proved the diagnosis of perforating necrobiosis lipoidica.

  6. [Development and current status of perforator flaps].

    Science.gov (United States)

    Xu, Dachuan; Zhang, Shimin; Tang, Maolin; Ouyang, Jun

    2011-09-01

    To provide a comprehensive review for development and existing problems of the perforator flaps. The related home and abroad literature concerning perforator flaps was extensively reviewed. The perforator flaps are defined as the axial flaps nourished solely by small cutaneous perforating vessels (perforating arteries and veins), which are exclusively composed of skin and subcutaneous fat. The perforator flaps have the advantages as follows: less injury at donor site, less damage to the contour of the donor site, good reconstruction and appearance of the recipient site flexible design, and short time of postoperative recovery, which have been widely used in reconstructive surgery. The perforator flaps are the new development of the microsurgery, which usher an era of small axial flaps; However, the controversies of the definition, vascular classification, the nomenclature, and the clinical application of the perforator flaps still exist, which are therefore the hot spot for future study.

  7. Intestinal perforation--a unique cause.

    Science.gov (United States)

    Kansal, G; Agrawal, V

    2000-04-01

    An illiterate, 65 years old, male attended surgery emergency with features of perforation peritonitis. Exploratory laparotomy revealed perforation in the terminal ileum and a sharp metallic object pointing at the perforation site. This, on removal, was found to be the sharp edge of a blister pack (with intact tablet within). The perforation was repaired. The abdomen was closed after leaving a drain. Postoperatively the patient had a morbid period and ultimately responded to management.

  8. On Asymptotic Behavior and Blow-Up of Solutions for a Nonlinear Viscoelastic Petrovsky Equation with Positive Initial Energy

    Directory of Open Access Journals (Sweden)

    Gang Li

    2013-01-01

    Full Text Available This paper deals with the initial boundary value problem for the nonlinear viscoelastic Petrovsky equation utt+Δ2u−∫0tgt−τΔ2ux,τdτ−Δut−Δutt+utm−1ut=up−1u. Under certain conditions on g and the assumption that mbehavior and blow-up results for solutions with positive initial energy.

  9. Localized Effects in the Nonlinear Behavior of Sandwich Panels with a Transversely Flexible Core

    DEFF Research Database (Denmark)

    Frostig, Y.; Thomsen, Ole Thybo

    2005-01-01

    nonlinear analysis approach incorporates the effects of the vertical flexibility of the core, and it is based on the approach of the High-order Sandwich Panel Theory (HSAPT). The results demonstrate that the effects of localized loads, when taken into the geometrically nonlinear domain, change the response...

  10. Generalized multiscale finite element methods for problems in perforated heterogeneous domains

    KAUST Repository

    Chung, Eric T.

    2015-06-08

    Complex processes in perforated domains occur in many real-world applications. These problems are typically characterized by physical processes in domains with multiple scales. Moreover, these problems are intrinsically multiscale and their discretizations can yield very large linear or nonlinear systems. In this paper, we investigate multiscale approaches that attempt to solve such problems on a coarse grid by constructing multiscale basis functions in each coarse grid, where the coarse grid can contain many perforations. In particular, we are interested in cases when there is no scale separation and the perforations can have different sizes. In this regard, we mention some earlier pioneering works, where the authors develop multiscale finite element methods. In our paper, we follow Generalized Multiscale Finite Element Method (GMsFEM) and develop a multiscale procedure where we identify multiscale basis functions in each coarse block using snapshot space and local spectral problems. We show that with a few basis functions in each coarse block, one can approximate the solution, where each coarse block can contain many small inclusions. We apply our general concept to (1) Laplace equation in perforated domains; (2) elasticity equation in perforated domains; and (3) Stokes equations in perforated domains. Numerical results are presented for these problems using two types of heterogeneous perforated domains. The analysis of the proposed methods will be presented elsewhere. © 2015 Taylor & Francis

  11. Hyperbilirubinemia as a predictor for appendiceal perforation

    DEFF Research Database (Denmark)

    Burcharth, J; Pommergaard, Hans-Christian; Rosenberg, J;

    2013-01-01

    Delayed or wrong diagnosis in patients with appendicitis can result in perforation and consequently increased morbidity and mortality. Serum bilirubin may be a useful marker for appendiceal perforation. The purpose of this systematic review was to evaluate studies investigating elevated serum...... bilirubin as a predictor for appendiceal perforation....

  12. Early Management Experience of Perforation after ERCP

    Directory of Open Access Journals (Sweden)

    Guohua Li

    2012-01-01

    Full Text Available Background and Aim. Perforation after endoscopic retrograde cholangiopancreatography (ERCP is a rare complication, but it is associated with significant mortality. This study evaluated the early management experience of these perforations. Patients and Methods. Between November 2003 and December 2011, a total of 8504 ERCPs were performed at our regional endoscopy center. Sixteen perforations (0.45% were identified and retrospectively reviewed. Results. Nine of these 16 patients with perforations were periampullary, 3 duodenal, 1 gastric fundus, and 3 patients had a perforation of an afferent limb of a Billroth II anastomosis. All patients with perforations were recognized during ERCP by X-ray and managed immediately. One patient with duodenal perforation and three patients with afferent limb perforation received surgery, others received medical conservative treatment which included suturing lesion, endoscopic nasobiliary drainage (ENBD, endoscopic retrograde pancreatic duct drainage (ERPD, gastrointestinal decompression, fasting, broad-spectrum antibiotics, and so on. All patients with perforation recovered successfully. Conclusions. We found that: (1 the diagnosis of perforation during ERCP may be easy, but you must pay attention to it. (2 Most retroperitoneal perforations can recover with only medical conservative treatment in early phase. (3 Most peritoneal perforations need surgery unless you can close the lesion up under endoscopy in early phase.

  13. Perforation due to ileocaecal salmonellosis

    NARCIS (Netherlands)

    Willemsen, PJ

    2002-01-01

    A 54-year old male patient was admitted with a tentative diagnosis of biliary pancreatitis. After 3 days, he developed an acute abdomen with a pneumoperitoneum. A laparotomy was performed : multiple perforations of the terminal ileum and a necrotic gallbladder were found. A right hemicolectomy with

  14. Perforation due to ileocaecal salmonellosis

    NARCIS (Netherlands)

    Willemsen, PJ

    2002-01-01

    A 54-year old male patient was admitted with a tentative diagnosis of biliary pancreatitis. After 3 days, he developed an acute abdomen with a pneumoperitoneum. A laparotomy was performed : multiple perforations of the terminal ileum and a necrotic gallbladder were found. A right hemicolectomy with

  15. The freestyle pedicle perforator flap

    DEFF Research Database (Denmark)

    Gunnarsson, Gudjon Leifur; Jackson, Ian T; Westvik, Tormod S;

    2015-01-01

    not widely performed by the general plastic surgeons. The aim of this paper is to present the simplicity of pedicled perforator flap reconstruction of moderate-sized defects of the extremities and torso. METHODS: We retrospectively reviewed the charts of 34 patients reconstructed using 34 freestyle pedicled...

  16. Perforated Peptic Ulcer: new insights

    NARCIS (Netherlands)

    M.J.O.E. Bertleff (Marietta)

    2011-01-01

    textabstractMuch has been written on perforated peptic ulcer (PPU) during the last hundred years. In 1500, when necropsies were first allowed, often a small hole was found in the anterior wall of the stomach, giving an explanation for symptoms of acute abdominal pain, nausea, vomiting which often le

  17. Impact of hydraulic perforation on fracture initiation and propagation in shale rocks

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xi; JU Yang; YANG Yong; SU Sun; GONG WenBo

    2016-01-01

    To enhance the oil and gas recovery rate,hydraulic fracturing techniques have been widely adopted for stimulation of low-permeability reservoirs.Pioneering work indicates that hydraulic perforation and layout could significantly affect fracture initiation and propagation in low-permeability reservoir rocks subjected to complex in-situ stresses.This paper reports on a novel numerical method that incorporates fracture mechanics principles and the numerical tools FRANC3D and ANSYS to investigate the three-dimensional initiation and propagation behavior of hydro-fracturing cracks in shale rock.Considering the transverse isotropic property of shale rocks,the mechanical parameters of reservoir rocks attained from laboratory tests were adopted in the simulation.The influence of perforation layouts on the 3D initiation of hydro-fracturing fractures in reservoir rocks under geo-stresses was quantitatively illuminated.The propagation and growth of fractures in three dimensions in different perforating azimuth values were illustrated.The results indicate that:1) the optimal perforation direction should be parallel to the maximum horizontal principal stress,2) the crack plane gradually turns toward the direction of the maximum horizontal principal stress when they are not in parallel,3) compared with the linear and symmetric pattern,the staggered perforation is the optimal one,4) the proper perforation density is four to six holes per meter,5) the optimal perforation diameter in this model is 30 mm,and 6) the influence of the perforation depth on the fracture initiation pressure is low.

  18. Unusual duodenal perforation following endoscopic retrograde cholangiopancreatography

    Directory of Open Access Journals (Sweden)

    Martin Kobborg

    2011-02-01

    Full Text Available Perforation is a known but rare complication to Endoscopic retrograde cholangiopancreatography (ERCP with endoscopic sphincterotomy (ES. Most of the perforations are located in the periampullary area due to ES. This report presents an unusual perforation in the third part of the duodenum following ES. The patient an eigthy-sixt-year-old man underwent ERCP with ES. The patient had Magnetic Resonance Cholangio-pancreatography (MRCP and Computerized Tomography (CT verified cholelithiasis and intra- and extrahepatic cholestasis. The perforation was not found under the ERCP procedure but was clinically revealed when the patient developed pneumoscrotum after the procedure. A CT-scan with oral contrast later confirmed the duodenal perforation.

  19. Evidence for bifurcation and universal chaotic behavior in nonlinear semiconducting devices

    Energy Technology Data Exchange (ETDEWEB)

    Testa, J.; Perez, J.; Jeffries, C.

    1982-01-01

    Bifurcations, chaos, and extensive periodic windows in the chaotic regime are observed for a driven LRC circuit, the capacitive element being a nonlinear varactor diode. Measurements include power spectral analysis; real time amplitude data; phase portraits; and a bifurcation diagram, obtained by sampling methods. The effects of added external noise are studied. These data yield experimental determinations of several of the universal numbers predicted to characterize nonlinear systems having this route to chaos.

  20. Global Behavior Of Finite Energy Solutions To The $d$-Dimensional Focusing Nonlinear Schr\\"odinger Equation

    CERN Document Server

    Guevara, Cristi

    2012-01-01

    We study the global behavior of finite energy solutions to the $d$-dimensional focusing nonlinear Schr\\"odinger equation (NLS), $i \\partial_t u+\\Delta u+ |u|^{p-1}u=0, $ with initial data $u_0\\in H^1,\\; x \\in R^n$. The nonlinearity power $p$ and the dimension $d$ are such that the scaling index $s=\\frac{d}2-\\frac2{p-1}$ is between 0 and 1, thus, the NLS is mass-supercritical $(s>0)$ and energy-subcritical $(s1,$ then the solution exhibits a blowup behavior, that is, either a finite time blowup occurs, or there is a divergence of $H^1$ norm in infinite time. This work generalizes the results for the 3d cubic NLS obtained in a series of papers by Holmer-Roudenko and Duyckaerts-Holmer-Roudenko with the key ingredients, the concentration compactness and localized variance, developed in the context of the energy-critical NLS and Nonlinear Wave equations by Kenig and Merle.

  1. A CLINICAL STUDY ON ILEAL PERFORATION

    Directory of Open Access Journals (Sweden)

    Kishore Babu

    2016-03-01

    Full Text Available INTRODUCTION Ileal perforation is a common problem seen in tropical countries, the commonest cause being typhoid fever. In western countries the causes are malignancy, trauma and mechanical aetiology, in the order of frequency.1,2,3 Over the years a definite changing trend has been observed in ileal perforations both in terms of causes, treatment and prognosis. Better antibiotics, aggressive surgery and the elimination of conservative treatment, better preoperative and postoperative care have all significantly contributed to the improvement in patient outcome.4,5 But still cases of ileal perforation cause a significant morbidity and mortality that persists despite the significant changes in health care over the years. AIMS AND OBJECTIVES To study the aetiology, presentation, management outcome and the factors influencing prognosis and outcome in ileal perforations. MATERIAL & METHODS Study Setting S. V. Medical College, Department of General Surgery, Tirupati. Study Period Patients attending S. V. Medical College, Department of General Surgery with perforation during the period from November 2012 to October 2015. Inclusion Criteria Patients between age group of more than 14 years presenting with pain abdomen and who are diagnosed to have ileal perforation in the intra operative period are selected. Exclusion Criteria Patients with peritonitis due to other causes like gastric, duodenum or large bowel perforation are excluded. Study Method The present study is a prospective study done on 28 patients of ileal perforation due to typhoid complication, nonspecific and traumatic perforations. History, clinical examination, investigations, operative findings, post-operative complications were recorded. In patients with non-traumatic perforations Widal test was done. CONCLUSION Typhoid fever and traumatic aetiology are the most common cause of Ileal perforation, followed by TB. Patients are more of male gender and are in reproductive age group. Widal

  2. Global existence, asymptotic behavior and blowup of solutions for a class of nonlinear wave equations with dissipative term

    Science.gov (United States)

    Zhijian, Yang

    The paper studies the global existence, asymptotic behavior and blowup of solutions to the initial boundary value problem for a class of nonlinear wave equations with dissipative term. It proves that under rather mild conditions on nonlinear terms and initial data the above-mentioned problem admits a global weak solution and the solution decays exponentially to zero as t→+∞, respectively, in the states of large initial data and small initial energy. In particular, in the case of space dimension N=1, the weak solution is regularized to be a unique generalized solution. And if the conditions guaranteeing the global existence of weak solutions are not valid, then under the opposite conditions, the solutions of above-mentioned problem blow up in finite time. And an example is given.

  3. NON-LINEAR DYNAMIC BEHAVIOR OF THERMOELASTIC CIRCULAR PLATE WITH VARYING THICKNESS SUBJECTED TO NON- CONSERVATIVE LOADING

    Institute of Scientific and Technical Information of China (English)

    WANG Zhongmin; GAO Jingbo; LI Huixia; LIU Hongzhao

    2008-01-01

    The non-linear dynamic behaviors of thermoelastic circular plate with varying thickness subjected to radially uniformly distributed follower forces are considered. Two coupled non-linear differential equations of motion for this problem are derived in terms of the transverse deflection and radial displacement component of the mid-plane of the plate. Using the Kantorovich averaging method, the differential equation of mode shape of the plate is derived, and the eigenvalue problem is solved by using shooting method. The eigencurves for frequencies and critical loads of the circular plate with unmovable simply supported edge and clamped edge are obtained. The effects of the variation of thickness and temperature on the frequencies and critical loads of the thermoelastic circular plate subjected to radially uniformly distributed follower forces are then discussed.

  4. NONLINEAR BUCKLING BEHAVIOR OF DAMAGED COMPOSITE SANDWICH PLATES CONSIDERING THE EFFECT OF TEMPERATURE-DEPENDENT THERMAL AND MECHANICAL PROPERTIES

    Institute of Scientific and Technical Information of China (English)

    Bai Ruixiang; Chen Haoran

    2001-01-01

    On the basis of the first-order shear deformation plate theory and the zig-zag deformation assumption, an incremental finite element formulation for nonlinear buckling analysis of the composite sandwich plate is deduced and the temperature-dependent thermal and mechanical properties of composite is considered. A finite element method for thermal or thermo-mechanical coupling nonlinear buckling analysis of the composite sandwich plate with an interfacial crack damage between face and core is also developed. Numerical results and discussions concerning some typical examples show that the effects of the variation of the thermal and mechanical properties with temperature, extermal compressive loading, size of the damage zone and piy angle of the faces on the thermal buckling behavior are significant.

  5. [Cocaine-related gastric perforation].

    Science.gov (United States)

    Ring, A; Stein, E; Stern, J

    2010-06-01

    Since the 1980s the abuse of cocaine has been -associated with gastroduodenal perforations in the United States. Here, we report the case of a 28-year-old man who came to our hospital with severe abdominal pain after smoking cocaine. Physical examination revealed generalised abdominal guarding. His X-ray did not show any free intraperitoneal air. However, there was a slightly elevated white blood cell count. Upon laparoscopic exploration of the abdomen, the -patient was found to have a generalised peritonitis secondary to a perforation of the prepyloric anterior wall. The operative procedure consisted of ulcer excision and primary closure with a pyloroplasty as well as an extensive abdominal irrigation after laparotomy.

  6. Neonatal and pediatric esophageal perforation.

    Science.gov (United States)

    Rentea, Rebecca M; St Peter, Shawn D

    2017-04-01

    Esophageal perforation (EP) is a rare complication that is often iatrogenic in origin. In contrast with adult patients in whom surgical closure of the defect is preferred, nonoperative treatment has become a common therapeutic approach for EP in neonates and children. Principles of management pediatric EP includes rapid diagnosis, appropriate hemodynamic monitoring and support, antibiotic therapy, total parenteral nutrition, control of extraluminal contamination, and restoration of luminal integrity either through time or operative approaches. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Perforating Disseminated Necrobiosis Lipoidica Diabeticorum

    OpenAIRE

    Paula Lozanova; Lyubomir Dourmishev; Snejina Vassileva; Ljubka Miteva; Maria Balabanova

    2013-01-01

    Perforating necrobiosis lipoidica is a very rare clinical variant which consists of degeneration and transepidermal elimination of the collagen with few cases reported in the literature. In two-thirds of the patients it associates with diabetes, with no relation with the glucose control. We present a 42-year-old female patient with a 7-year history of diabetes on insulin therapy, referred to our clinic with a 3-year history of multiple asymptomatic firm plaques disseminated on the upper and l...

  8. Colonic perforation in Behcet's syndrome

    Institute of Scientific and Technical Information of China (English)

    Catherine M Dowling; Arnold DK Hill; Carmel Malone; John J Sheehan; Shona Tormey; Kieran Sheahan; Enda McDermott; Niall J O'Higgins

    2008-01-01

    A 17-year-old gentleman was admitted to our hospital for headache, the differential diagnosis of which included Behcet's syndrome (BS). He developed an acute abdomen and was found to have air under the diaphragm on erect chest X-ray. Subsequent laparotomy revealed multiple perforations throughout the colon. This report describes an unusual complication of Behcets syndrome occurring at the time of presentation and a review of the current literature of reported cases.

  9. Colonic perforation in Behcet's syndrome.

    Science.gov (United States)

    Dowling, Catherine-M; Hill, Arnold-Dk; Malone, Carmel; Sheehan, John-J; Tormey, Shona; Sheahan, Kieran; McDermott, Enda; O'Higgins, Niall-J

    2008-11-14

    A 17-year-old gentleman was admitted to our hospital for headache, the differential diagnosis of which included Behcet's syndrome (BS). He developed an acute abdomen and was found to have air under the diaphragm on erect chest X-ray. Subsequent laparotomy revealed multiple perforations throughout the colon. This report describes an unusual complication of Behcets syndrome occurring at the time of presentation and a review of the current literature of reported cases.

  10. Intraperitoneal explosion following gastric perforation.

    Science.gov (United States)

    Mansfield, Scott K; Borrowdale, Roderick

    2014-04-01

    The object of this study is to report a rare case of explosion during laparotomy where diathermy ignited intraperitoneal gas from a spontaneous stomach perforation. Fortunately, the patient survived but the surgeon experienced a finger burn. A literature review demonstrates other examples of intraoperative explosion where gastrointestinal gases were the fuel source. Lessons learned from these cases provide recommendations to prevent this potentially lethal event from occurring.

  11. Combining rhinoplasty with septal perforation repair.

    Science.gov (United States)

    Foda, Hossam M T; Magdy, Emad A

    2006-11-01

    A combined septal perforation repair and rhinoplasty was performed in 80 patients presenting with septal perforations (size 1 to 5 cm) and external nasal deformities. The external rhinoplasty approach was used for all cases and the perforation was repaired using bilateral intranasal mucosal advancement flaps with a connective tissue interposition graft in between. Complete closure of the perforation was achieved in 90% of perforations of size up to 3.5 cm and in only 70% of perforations that were larger than 3.5 cm. Cosmetically, 95% were very satisfied with their aesthetic result. The external rhinoplasty approach proved to be very helpful in the process of septal perforation repair especially in large and posteriorly located perforations and in cases where the caudal septal cartilage was previously resected. Our results show that septal perforation repair can be safely combined with rhinoplasty and that some of the routine rhinoplasty maneuvers, such as medial osteotomies and dorsal lowering, could even facilitate the process of septal perforation repair.

  12. CT in acute perforated sigmoid diverticulitis

    Energy Technology Data Exchange (ETDEWEB)

    Lohrmann, Christian [Division of Diagnostic Radiology, Department of Radiology, University Hospital of Freiburg, Hugstetter Strasse 55, 79106 Freiburg (Germany)]. E-mail: lohrmann@mrs1.ukl.uni-freiburg.de; Ghanem, Nadir [Division of Diagnostic Radiology, Department of Radiology, University Hospital of Freiburg, Hugstetter Strasse 55, 79106 Freiburg (Germany); Pache, Gregor [Division of Diagnostic Radiology, Department of Radiology, University Hospital of Freiburg, Hugstetter Strasse 55, 79106 Freiburg (Germany); Makowiec, Frank [Department of Surgery, University Hospital of Freiburg, Hugstetter Strasse 55, 79106 Freiburg (Germany); Kotter, Elmar [Division of Diagnostic Radiology, Department of Radiology, University Hospital of Freiburg, Hugstetter Strasse 55, 79106 Freiburg (Germany); Langer, Mathias [Division of Diagnostic Radiology, Department of Radiology, University Hospital of Freiburg, Hugstetter Strasse 55, 79106 Freiburg (Germany)

    2005-10-01

    Background: To assess the value of computed tomography (CT) in patients with acute perforated sigmoid diverticulitis in correlation with the Hinchey classification of perforated diverticular disease. Methods: Thirty patients with acute perforated sigmoid diverticulitis underwent computed tomography prior to surgery. Computed tomography scans were compared with the surgical and histopathological reports, utilizing the Hinchey classification. Results: In 28 of the 30 (93%) patients examined, the Hinchey stage was correctly determined by means of computed tomography. One patient with Hinchey stage IV was falsely classified as Hinchey stage III, and one patient with Hinchey stage III as Hinchey stage II. Computed tomography revealed 12 out of 14 (86%) patients with perforation sites and 3 out of 3 (100%) patients with contained perforation. In one of 17 (6%) patients with surgically or histopathologically proven perforation or contained perforation, a bowel wall discontinuity was revealed by computed tomography. In 6 of the 17 (35%) patients with surgical or histopathological perforation or contained perforation, extraluminal contrast material was detected by computed tomography. Conclusions: Computed tomography is a valuable imaging tool for determining the degree of acute perforated sigmoid diverticulitis, by means of which patients can be stratified according to the severity of the disease; furthermore, this tool is of assistance in surgical planning.

  13. Perforated duodenal ulcer: Emerging pattern

    Directory of Open Access Journals (Sweden)

    Murtaza Ali Asger Calcuttawala

    2014-01-01

    Full Text Available Background: A total of 27 patients of perforated duodenal ulcer admitted in our institution between December 2010 and November 2012 were treated and studied. Materials and Methods: All patients were diagnosed on the basis of clinical and radiological findings, exploratory laparotomy was performed and simple closure of perforation with placement of Graham′s omental patch was carried out. This was followed by triple regimen for Helicobacter pylori eradication. Results: All patients were male, maximum incidence (61.54% was noted in the age group of 21-30, ′O′ +ve blood group was most commonly observed in our patients. Eight patients had history suggestive of acute acid peptic disease. Mean time interval between the start of symptoms and surgery was 43 h. No morbidity except minimal pleural effusion was seen in one case. There was no mortality in our series. Conclusion: We conclude that although a number of definitive surgeries have been described for acid peptic disease, but the requirement of such procedures has come down due to increasing use of H. pylori eradication therapy and proton pump inhibitors. However, surgery for complications especially for duodenal ulcer perforation has not reduced concomitantly. Incidence is greater in young males.

  14. Dynamic Critical Behavior of Multi-Grid Monte Carlo for Two-Dimensional Nonlinear $\\sigma$-Models

    OpenAIRE

    Mana, Gustavo; Mendes, Tereza; Pelissetto, Andrea; Sokal, Alan D.

    1995-01-01

    We introduce a new and very convenient approach to multi-grid Monte Carlo (MGMC) algorithms for general nonlinear $\\sigma$-models: it is based on embedding an $XY$ model into the given $\\sigma$-model, and then updating the induced $XY$ model using a standard $XY$-model MGMC code. We study the dynamic critical behavior of this algorithm for the two-dimensional $O(N)$ $\\sigma$-models with $N = 3,4,8$ and for the $SU(3)$ principal chiral model. We find that the dynamic critical exponent $z$ vari...

  15. Theoretical prediction of electrocaloric effect based on non-linear behaviors of dielectric permittivity under temperature and electric fields

    Directory of Open Access Journals (Sweden)

    Hongbo Liu

    2015-11-01

    Full Text Available The electrocaloric (EC effect has been paid great attentions recently for applications on cooling or electricity generation. However, the directly commercial measurement equipment for the effect is still unavailable. Here we report a novel method to predict EC effect by non-linear behaviors of dielectric permittivity under temperature and electric fields. According to the method, the analytical equations of EC temperature change ΔT are directly given for normal ferroelectrics and relaxor. The calculations have been performed on several materials and it is shown that the method is suitable for both inorganic and organic ferroelectrics, and relaxor.

  16. Experimental investigation of perforations interactions effects under high sound pressure levels

    CERN Document Server

    Tayong, Rostand

    2009-01-01

    Most models for predicting the acoustic response of perforated panels are based on the assumption that there is no interactions between the holes. The common way of taking into account the perforates effects is the use of Fok's functions. The few papers that deal with these effects study the case of low sound pressure levels. This paper investigates the Holes Interaction Effects (HIE) of perforated and micro-perforated panels when submitted to high sound pressure levels. Analysis of the data yields to the fact that even with HIE, the nonlinear reactance dependency with velocity is very slight. The HIE can provide good absorption of the perforated panel backed by an air cavity at low and high sound pressure levels if the holes positions are well configured. Perforated panels of holes diameters less than 2 millimeters were built out of steel with different interstices (distance between two adjacent holes) and tested. Experimental results (performed with an impedance tube) in the cases of interaction are done an...

  17. Energy Impacts of Nonlinear Behavior of PCM When Applied into Building Envelope

    Energy Technology Data Exchange (ETDEWEB)

    Tabares-Velasco, P. C. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2012-08-01

    Presented at the ASME 2012 6th International Conference on Energy Sustainability & 10th Fuel Cell Science, Engineering and Technology Conference on July 23-26, 2012, this study analyzes the effects a nonlinear enthalpy profile has on thermal performance and expected energy benefits for PCM-enhanced insulation.

  18. Effects on the Floor Response Spectra by the Nonlinear Behavior of a Seismic Base Isolation System

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hyungkui; Kim, Jung Han; Choi, Inkil [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    An evaluation of safety being carried out for various risk factors of prevents for nuclear power plant accident. In general, an evaluation of the structural integrity was performed about seismic risk. In recent years, an assessment of integrity of internal equipment being carried out for earthquake loads owing to the possibility of severe accidents caused by the destruction of internal equipment or a blackout. Floor response spectra of the structure should be sought for evaluating of the integrity of internal equipment. The floor response spectra depends on the characteristics of seismic base isolation system such as the natural frequency, damping ratio, and height of the floor of the structure. An evaluation of the structural integrity using the equivalent stiffness of the seismic base isolation system was satisfactory. In this study, the effect of the non-linearity of isolated system in the floor response spectrum of the structure is analyzed. In this study, the floor response spectrum of the seismic base isolation system by the non-linear effect of the rubber isolator was analyzed. As a result, the influence of the non-linear isolated system was increased in hi-frequency domain. In addition, each floor exhibited a more different of responses compared with the equivalent linear model of the isolated structure. The non-linearity of the isolation system of the structure was considered, because of a more reliable assessment of integrity of equipment at each floor of seismic base the isolation system.

  19. On the asymptotic behavior of solutions of certain third-order nonlinear differential equations

    Directory of Open Access Journals (Sweden)

    Cemil Tunç

    2005-01-01

    Full Text Available We establish sufficient conditions under which all solutions of the third-order nonlinear differential equation x ⃛+ψ(x,x˙,x¨x¨+f(x,x˙=p(t,x,x˙,x¨ are bounded and converge to zero as t→∞.

  20. Emergency control of unstable behavior of nonlinear systems induced by fault

    Directory of Open Access Journals (Sweden)

    Mark A. Pinsky

    1998-01-01

    -functions significantly simplifying analysis and control of fault phenomena. The design of an mergency controller is based on the technique for computing fault-induced jumps of the system states, which is described in the paper. An emergency controller instantaneously returning states of a sample nonlinear system to its stability basin is designed.

  1. Social Contagion, Adolescent Sexual Behavior, and Pregnancy: A Nonlinear Dynamic EMOSA Model.

    Science.gov (United States)

    Rodgers, Joseph Lee; Rowe, David C.; Buster, Maury

    1998-01-01

    Expands an existing nonlinear dynamic epidemic model of onset of social activities (EMOSA), motivated by social contagion theory, to quantify the likelihood of pregnancy for adolescent girls of different sexuality statuses. Compares five sexuality/pregnancy models to explain variance in national prevalence curves. Finds that adolescent girls have…

  2. Freestyle Local Perforator Flaps for Facial Reconstruction

    Directory of Open Access Journals (Sweden)

    Jun Yong Lee

    2015-01-01

    Full Text Available For the successful reconstruction of facial defects, various perforator flaps have been used in single-stage surgery, where tissues are moved to adjacent defect sites. Our group successfully performed perforator flap surgery on 17 patients with small to moderate facial defects that affected the functional and aesthetic features of their faces. Of four complicated cases, three developed venous congestion, which resolved in the subacute postoperative period, and one patient with partial necrosis underwent minor revision. We reviewed the literature on freestyle perforator flaps for facial defect reconstruction and focused on English articles published in the last five years. With the advance of knowledge regarding the vascular anatomy of pedicled perforator flaps in the face, we found that some perforator flaps can improve functional and aesthetic reconstruction for the facial defects. We suggest that freestyle facial perforator flaps can serve as alternative, safe, and versatile treatment modalities for covering small to moderate facial defects.

  3. Diagnosis of perforated gastric ulcers by ultrasound.

    Science.gov (United States)

    Wallstabe, L; Veitt, R; Körner, T

    2002-10-01

    Patients with a perforation of the gastrointestinal tract need fast confirmation of diagnosis and early treatment to improve outcome. Plain abdominal x-ray does not always prove the perforation particularly at early stage. We report about a 62 year-old woman complaining of consistent abdominal pain with sudden onset. Ultrasound was taken as first diagnostic measure, revealing a perforation. The leakage was located in the stomach. Radiography confirmed the pneumoperitoneum without indicating the perforated location. During operation the perforated gastric ulcer was found and sutured. This case report points out the reliability of ultrasound in diagnosing a pneumoperitoneum. Additionally it provides a summary of ultrasound signs seen in perforated gastric and duodenal ulcers and a review of literature.

  4. Dimensions of stabident intraosseous perforators and needles.

    Science.gov (United States)

    Ramlee, R A; Whitworth, J

    2001-09-01

    Problems can be encountered inserting intraosseous injection needles through perforation sites. This in vitro study examined the variability and size compatibility of Stabident intraosseous injection components. The diameters of 40 needles and perforators from a single Stabident kit were measured in triplicate with a toolmakers microscope. One-way ANOVA revealed that mean needle diameter (0.411 mm) was significantly narrower than mean perforator diameter (0.427 mm) (p < 0.001). A frequency distribution plot revealed that needle diameter followed a normal distribution, indicating tight quality control during manufacture. The diameter of perforators was haphazardly distributed, with a clustering of 15% at the lower limit of the size range. However on no occasion was the diameter of a perforator smaller than that of an injection needle. We conclude that components of the Stabident intraosseous anaesthetic system are size-compatible, but there is greater and more haphazard variability in the diameter of perforators than injection needles.

  5. Freestyle Local Perforator Flaps for Facial Reconstruction.

    Science.gov (United States)

    Lee, Jun Yong; Kim, Ji Min; Kwon, Ho; Jung, Sung-No; Shim, Hyung Sup; Kim, Sang Wha

    2015-01-01

    For the successful reconstruction of facial defects, various perforator flaps have been used in single-stage surgery, where tissues are moved to adjacent defect sites. Our group successfully performed perforator flap surgery on 17 patients with small to moderate facial defects that affected the functional and aesthetic features of their faces. Of four complicated cases, three developed venous congestion, which resolved in the subacute postoperative period, and one patient with partial necrosis underwent minor revision. We reviewed the literature on freestyle perforator flaps for facial defect reconstruction and focused on English articles published in the last five years. With the advance of knowledge regarding the vascular anatomy of pedicled perforator flaps in the face, we found that some perforator flaps can improve functional and aesthetic reconstruction for the facial defects. We suggest that freestyle facial perforator flaps can serve as alternative, safe, and versatile treatment modalities for covering small to moderate facial defects.

  6. Stercoral colonic diverticulum perforation with jejunal diverticulitis mimicking upper gastrointestinal perforation

    Institute of Scientific and Technical Information of China (English)

    BI Jing-tao; GUO Yan-tong; ZHAO Jing-ming; ZHANG Zhong-tao

    2012-01-01

    Stercoral perforation of the colon is an unusual pathological condition with fewer than 150 cases reported in the literature to date.We present a case of stercoral colonic perforation mimicking upper gastrointestinal perforation,which was diagnosed by computed tomography preoperatively.However,at laparotomy,stercoral colonic diverticulum perforation with jejunal diverticulitis became the most appropriate diagnosis.Colonic perforation is a severe complication in surgery.It is a rather uncommon event usually caused by malignancy,diverticular disease,trauma or ulcerative colitis.Stercoral perforation of the colon was reported by Berry1 in 1894.Fewer than 150 cases have been reported in the literature to date.2,3 We present a rare case of stercoral diverticulum colonic perforation with jejunal diverticulitis mimicking upper gastrointestinal (GI) perforation,which was correctly diagnosed at laparotomy.

  7. Spontaneous ileal perforation complicating low anorectal malformation

    Directory of Open Access Journals (Sweden)

    TiJesuni Olatunji

    2015-01-01

    Full Text Available Anorectal malformation is a common anomaly in neonates. Although colorectal perforations have been reported as a complication, ileal perforation is rarely encountered. This is a report of a 2-day-old boy presenting with a low anorectal malformation, complicated with ileal perforation, necessitating laparotomy and ileal repair. Anoplasty was done for the low anomaly. Early presentation and prompt treatment of anorectal malformations is important to prevent such potential life threatening complication.

  8. A CALCULUS CHOLECYSTITIS PERFORATING AT THE NECK

    Directory of Open Access Journals (Sweden)

    Jayashri

    2014-08-01

    Full Text Available Gallbladder perforation is a rare complication of cholecystitis and cholelithiasis. The high morbidity and mortality rates associated with this condition are due to delays in diagnosis and treatment since signs and symptoms of perforation do not differ significantly from those of uncomplicated cholecystitis. We report a case of 17 year old boy who presented with perforation at the neck of gall bladder with extrusion of a stone. It was associated with bile infected with S. typhi.

  9. Management of biliary perforation in children

    Directory of Open Access Journals (Sweden)

    Mirza Bilal

    2010-01-01

    Full Text Available Background: To study the aetiology, management and outcome of biliary perforations in paediatric age group. Patients and Methods: In a retrospective study, the records of patients presented with biliary peritonitis due to biliary perforations, managed from March 2006 to July 2009, are reviewed. Results: Eight male patients with biliary peritonitis due to biliary perforation were managed. These patients were divided in two groups, A and B. Group A, (n = 3 patients, had common bile duct (CBD perforation, and Group B (n=5 patients had gallbladder perforation. The presenting features were abdominal pain, fever, abdominal distension, vomiting, constipation, jaundice and signs of peritonism. The management of CBD perforations in Group A was by draining the site of perforation and biliary diversion (tube cholecystostomy. In Group B, the gallbladder perforations were managed by tube cholecystostomy in four patients and cholecystectomy in one patient, however, one patient had to be re-explored and cholecystectomy performed due to complete necrosis of gall bladder. There was no mortality in our series. All patients were asymptomatic on regular follow-up. Conclusion: Early optimal management of biliary perforations remarkably improved the very high mortality and morbidity that characterised this condition in the past.

  10. Minimally invasive treatments for perforator vein insufficiency.

    Science.gov (United States)

    Kuyumcu, Gokhan; Salazar, Gloria Maria; Prabhakar, Anand M; Ganguli, Suvranu

    2016-12-01

    Incompetent superficial veins are the most common cause of lower extremity superficial venous reflux and varicose veins; however, incompetent or insufficient perforator veins are the most common cause of recurrent varicose veins after treatment, often unrecognized. Perforator vein insufficiency can result in pain, skin changes, and skin ulcers, and often merit intervention. Minimally invasive treatments have replaced traditional surgical treatments for incompetent perforator veins. Current minimally invasive treatment options include ultrasound guided sclerotherapy (USGS) and endovascular thermal ablation (EVTA) with either laser or radiofrequency energy sources. Advantages and disadvantages of each modality and knowledge on these treatments are required to adequately address perforator venous disease.

  11. Nonlinear Dynamics and Bifurcation Behavior of a 2-DOF Spring Resonator with End Stopper for Energy Harvesting

    Directory of Open Access Journals (Sweden)

    El Aroudi A.

    2014-01-01

    Full Text Available In this paper, the model of a two-degree-of-freedom (2-DOF spring resonator with end stopper for an energy harvesting application is presented. Then we characterize its nonlinear dynamical behavior by numerical simulations when some suitable parameters are varied. The system is formed by two resonators subject to external vibrational excitation and with an end stopper. We present the continuous time dynamical model of the system in the form of a switched fourth order differential equation. Harmonic vibrations are considered as the main ambient energy source for the system and its frequency response representing the RMS value of the displacement is first computed. The dynamical behavior is unveiled by computing state-space trajectories, timedomain series and FFT spectra and frequency response as the excitation amplitude is varied.

  12. Modeling the Non-Linear Behavior of Library Cells for an Accurate Static Noise Analysis

    CERN Document Server

    Forzan, Cristiano

    2011-01-01

    In signal integrity analysis, the joint effect of propagated noise through library cells, and of the noise injected on a quiet net by neighboring switching nets through coupling capacitances, must be considered in order to accurately estimate the overall noise impact on design functionality and performances. In this work the impact of the cell non-linearity on the noise glitch waveform is analyzed in detail, and a new macromodel that allows to accurately and efficiently modeling the non-linear effects of the victim driver in noise analysis is presented. Experimental results demonstrate the effectiveness of our method, and confirm that existing noise analysis approaches based on linear superposition of the propagated and crosstalk-injected noise can be highly inaccurate, thus impairing the sign-off functional verification phase.

  13. Solitonic and chaotic behaviors for the nonlinear dust-acoustic waves in a magnetized dusty plasma

    Science.gov (United States)

    Zhen, Hui-Ling; Tian, Bo; Xie, Xi-Yang; Wu, Xiao-Yu; Wen, Xiao-Yong

    2016-05-01

    A model for the nonlinear dust-ion-acoustic waves in a two-ion-temperature, magnetized dusty plasma is studied in this paper. Via the symbolic computation, one-, two- and N-soliton solutions are obtained. It is found that when √{μeμi }parallel during the propagation on the x - y, x - t, and y - t planes, where x, y, and z are the scaled spacial coordinates, and t is the retarded time. Upon the introduction of the driving force Γ(t ) , both the developed and weak chaotic motions as well as the effect of Γ(t ) are explored. Via the phase projections and power spectra, we find the difference between the two chaotic motions roots in the relative magnitude of nonlinearity and external force. Increasing the frequency of the external force or the strength of the damped term can weaken the chaotic motions of such a forced model.

  14. The effect of process delay on dynamical behaviors in a self-feedback nonlinear oscillator

    Science.gov (United States)

    Yao, Chenggui; Ma, Jun; Li, Chuan; He, Zhiwei

    2016-10-01

    The delayed feedback loops play a crucial role in the stability of dynamical systems. The effect of process delay in feedback is studied numerically and theoretically in the delayed feedback nonlinear systems including the neural model, periodic system and chaotic oscillator. The process delay is of key importance in determining the evolution of systems, and the rich dynamical phenomena are observed. By introducing a process delay, we find that it can induce bursting electric activities in the neural model. We demonstrate that this novel regime of amplitude death also exists in the parameter space of feedback strength and process delay for the periodic system and chaotic oscillator. Our results extend the effect of process delay in the paper of Zou et al.(2013) where the process delay can eliminate the amplitude death of the coupled nonlinear systems.

  15. Nonlinear dynamic behaviors of clamped laminated shallow shells with one-to-one internal resonance

    Science.gov (United States)

    Abe, Akira; Kobayashi, Yukinori; Yamada, Gen

    2007-07-01

    This paper investigates one-to-one internal resonance of laminated shallow shells with rigidly clamped edges. It is assumed that the natural frequencies ω2 and ω3 of two asymmetric (second and third) vibration modes have the relationship ω2≈ ω3. The displacements are expressed by using eigenvectors for linear vibration modes calculated by the Ritz method. Applying Galerkin's procedure to the equation of motion, nonlinear differential equations are derived. By considering the first vibration mode in addition to the two asymmetric vibration modes, quadratic nonlinear terms expressing the interaction between the asymmetric and the first modes appear in the differential equations. Shooting method is used to obtain the steady-state response when the driving frequency Ω is near ω2. The dynamic characteristics of the shells with the internal resonance are discussed.

  16. Long-time behavior of a class of thermoelastic plates with nonlinear strain

    Science.gov (United States)

    Fatori, L. H.; Jorge Silva, M. A.; Ma, T. F.; Yang, Zhijian

    2015-11-01

    In recent years a class of vibrating plates with nonlinear strain of p-Laplacian type was studied by several authors. The present paper contains a first thermoelastic model of that class of problems including both Fourier and non-Fourier heat laws. Our main result establishes the existence of global and exponential attractors for the strongly damped problem through a stabilizability inequality. In addition, for the weakly damped problem, we establish the exponential stability of its Galerkin semiflows.

  17. LARGE TIME BEHAVIOR OF SOLUTIONS TO NONLINEAR VISCOELASTIC MODEL WITH FADING MEMORY

    Institute of Scientific and Technical Information of China (English)

    Yanni Zeng

    2012-01-01

    We study the Cauchy problem of a one-dimensional nonlinear viscoelastic model with fading memory. By introducing appropriate new variables we convert the integro-partial differential equations into a hyperbolic system of balance laws.When it is a perturbation of a constant state,the solution is shown time asymptotically approaching to predetermined diffusion waves.Pointwise estimates on the convergence details are obtained.

  18. Linear and Nonlinear Behavior Analysis of a Flexible Shaft Supported By Hydrostatic Squeeze Film Dampers

    Directory of Open Access Journals (Sweden)

    A. Bouzidane

    2014-01-01

    Full Text Available Linear and non linear models of a hydrostatic squeeze film damper are presented and numerically simulated by a step by step method on a modal basis, in order to study the non-linear dynamic behaviour of a flexible shaft. The Reynolds equation is solved at each step in order to evaluate the film forces. The equations of motion are then integrated by using the Newmark method with a variable step in order to obtain speeds and the position for the next step. The non-linear hydrostatic forces are determined by the application of the boundary conditions, and the integration of the pressure field is determined by resolution of Reynolds equation, by applying the central finite difference method. The aim of this research is to study the effect of pressure ratio, viscosity, and rotational speeds on the vibratory responses and the transmitted bearing forces. The results are discussed, analysed and compared to a linear approach which is restricted to only small vibrations around the equilibrium position. The results show good agreements between linear and non-linear methods when the unbalance force is small, and then the linear model may be used for small vibrations in order to reduce compilation time during the iterative process.

  19. Nonlinear flexural waves and chaos behavior in finite-deflection Timoshenko beam

    Institute of Scientific and Technical Information of China (English)

    Shan-yuan ZHANG; Zhi-fang LIU

    2010-01-01

    Based on the Timoshenko beam theory,the finite-deflection and the axial inertia are taken into account,and the nonlinear partial differential equations for flexural waves in a beam are derived. Using the traveling wave method and integration skills,the nonlinear partial differential equations can be converted into an ordinary differential equation. The qualitative analysis indicates that the corresponding dynamic system has a heteroclinic orbit under a certain condition. An exact periodic solution of the nonlinear wave equation is obtained using the Jacobi elliptic function expansion. When the modulus of the Jacobi elliptic function tends to one in the degenerate case,a shock wave solution is given. The small perturbations are further introduced,arising from the damping and the external load to an original Hamilton system,and the threshold condition of the existence of the transverse heteroclinic point is obtained using Melnikov's method. It is shown that the perturbed system has a chaotic property under the Smale horseshoe transform.

  20. Nonlinear Behavior of Single Piles in Jacket Type Offshore Platforms Using Incremental Dynamic Analysis

    Directory of Open Access Journals (Sweden)

    Mohammad A. Assareh

    2008-01-01

    Full Text Available The operation for offshore oil has become an important issue in the recent years. Offshore platforms are some of those structures which are built to withstand environmental and accidental loads during oil exploitation operation. One of the most usual types of these platforms is the Jacket Type Offshore Platform (JTOP which can be divided into three important parts, which are Deck, Jacket and piles. In order to increase the safety, particular attention should be paid to earthquake excitations which are directly applied to the piles of these structures. Nonlinearity in piles and buckling of the struts are important issues which have to be considered by the designers of offshore platforms. The case of nonlinearity in piles and failure capture in these members has not effectively been covered by researchers. Incremental Dynamic Analysis (IDA is a powerful tool to assess the capacity of a structure upon seismic loads. In this paper incremental dynamic analysis has been implemented on single piles considering soil-pile interactions and free field site response. The use of nonlinear materials and lateral load resisting elements in the incremental dynamic analysis done in this paper has made it possible to get promising insights for incorporation of appropriate limit states and applications of performance based engineering. Special Engineering Demand Parameters (EDP and Intensity Measures (IM have been introduced for the single pile dynamic analysis in jacket type offshore platforms.

  1. Third-Order Nonlinear Optical Behavior of Novel Polythiophene Derivatives Functionalized with Disperse Red 19 Chromophore

    Directory of Open Access Journals (Sweden)

    Marilú Chávez-Castillo

    2015-01-01

    Full Text Available Two copolymers of 3-alkylthiophene (alkyl = hexyl, octyl and a thiophene functionalized with disperse red 19 (TDR19 as chromophore side chain were synthesized by oxidative polymerization. The synthetic procedure was easy to perform, cost-effective, and highly versatile. The molecular structure, molecular weight distribution, film morphology, and optical and thermal properties of these polythiophene derivatives were determined by NMR, FT-IR, UV-Vis GPC, DSC-TGA, and AFM. The third-order nonlinear optical response of these materials was performed with nanosecond and femtosecond laser pulses by using the third-harmonic generation (THG and Z-scan techniques at infrared wavelengths of 1300 and 800 nm, respectively. From these experiments it was observed that although the TRD19 incorporation into the side chain of the copolymers was lower than 5%, it was sufficient to increase their nonlinear response in solid state. For instance, the third-order nonlinear electric susceptibility (χ3 of solid thin films made of these copolymers exhibited an increment of nearly 60% when TDR19 incorporation increased from 3% to 5%. In solution, the copolymers exhibited similar two-photon absorption cross sections σ2PA with a maximum value of 8545 GM and 233 GM (1 GM = 10−50 cm4 s per repeated monomeric unit.

  2. Research on strip hysteretic behavior and mill vertical vibration system nonlinear dynamics

    Science.gov (United States)

    Fan, Xiaobin; Zang, Yong; Jin, Ke

    2016-10-01

    Rolling mill vibration is a technical problem in the iron and steel industry for many years and has serious impact and harm on production. There were serious vibrations in the middle mills when rolling thin container strip for the compact strip production (CSP) strip hot rolling process. This paper studied the hysteretic characteristic of rolled strip and established the vertical vibration system single-degree-of-freedom dynamics model of the F3 mill rollers. The influence of parameters on the system characteristics was studied, such as the linear damping coefficient, linear stiffness coefficient, nonlinear displacement coefficient, nonlinear velocity coefficient and exciting force, and then, the vibration source and vibration-restraining measure were studied from the roll gap. The results show that with increasing linear stiffness, damping and hysteresis coefficient, it can reduce the possibility of chaotic system; the linear stiffness coefficient had the greatest influence, and hysteresis damping coefficient had minimal influence on chaotic threshold. In order to reduce rolling mill vibration amplitude, we should reduce the external excitation force firstly, and in order to improve the dynamic performance of the system, we should control the speed of nonlinear coefficient values. The contrast experiments were carried out at the production scene finally.

  3. Iatrogenic esophageal perforation in a newborn

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jeong Mi; Yeon, Kyung Mo; Park, Won Soon; Choi, Jung Hwan [College of Medicine, Seoul National Univ., Seoul (Korea, Republic of)

    1990-07-15

    Esophagus and pharyngeal structures of newborn are very week and so vulnerable. When a parallel longitudinal tubular structure around (especially behind) the esophagus is seen, traumatic esophageal perforation must be differentiated. We report a case of esophageal perforation in a premature twin baby by nasogastric tube insertion.

  4. Energy Impacts of Nonlinear Behavior of PCM When Applied into Building Envelope: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Tabares-Velasco, P. C.

    2012-08-01

    Previous research on phase change materials (PCM) for building applications has been done for several decades resulting in plenty of literature on PCM properties, temperature, and peak reduction potential. Thus, PCMs are a potential technology to reduce peak loads and HVAC energy consumption in buildings. There are few building energy simulation programs that have PCM modeling features, and even fewer have been validated. Additionally, there is no previous research that indicates the level of accuracy when simulating PCM from a building energy simulation perspective. This study analyzes the effects a nonlinear enthalpy profile has on thermal performance and expected energy benefits for PCM-enhanced insulation.

  5. Model for nonlinear behavior in the self-amplified spontaneous-emission free-electron laser

    Science.gov (United States)

    Krinsky, S.

    2004-06-01

    We introduce a simplified model for the saturation of a self-amplified spontaneous-emission free-electron laser. Within this model, we determine the effect of nonlinearity upon the statistical properties of the output radiation. Comparing our results with the computer simulations of Saldin, Schneidmiller, and Yurkov [The Physics of Free Electron Lasers (Springer-Verlag, Berlin, 2000)], we find that the model provides a good description of the average intensity, field correlation function, and coherence time, but underestimates the intensity fluctuation. Asymmetric spectral broadening phenomena are not included in the model.

  6. Nonlinear Constitutive Equation for Green Sand Considering the Tri-axial Compression Behavior

    Institute of Scientific and Technical Information of China (English)

    曾攀; 孔劲

    2004-01-01

    The compression characteristics of green sand were investigated experimentally, including the squeezing and yielding during deformation. An expression was developed for the transient compression modulus of sand during compression. Based on the hypothesis put forward of the compression state, the differential equation for the nonlinear constitutive equation was deduced by introducing a move-yield potential function. The state constitutive equation under the tri-axial experiment is further studied according to the sand attributes, considering the differential form of Hooke's law and the Mohr-Coulomb condition. The related experiment data are applied to verify the proposed constitutive model of sand.

  7. On tail behavior of nonlinear autoregressive functional conditional heteroscedastic model with heavy-tailed innovations

    Institute of Scientific and Technical Information of China (English)

    PAN; Jiazhu; WU; Guangxu

    2005-01-01

    We study the tail probability of the stationary distribution of nonparametric nonlinear autoregressive functional conditional heteroscedastic (NARFCH) model with heavytailed innovations. Our result shows that the tail of the stationary marginal distribution of an NARFCH series is heavily dependent on its conditional variance. When the innovations are heavy-tailed, the tail of the stationary marginal distribution of the series will become heavier or thinner than that of its innovations. We give some specific formulas to show how the increment or decrement of tail heaviness depends on the assumption on the conditional variance function. Some examples are given.

  8. [Gastric perforation associated with Candida infection].

    Science.gov (United States)

    Bollo, Jesús; Carrilo, Elena; Lupu, Ion; Caballero, Ferran; Trias, Manel

    2009-01-01

    Notable causes of gastroduodenal ulcer are Helicobacter pylori infection, intake of non-steroidal anti-inflammatory agents, neoplastic disease, acid hypersecretory states and secondary peptic ulcer disease. There are case reports of healthy patients or those with risk factors for fungal infection who develop gastroduodenal ulcer perforation associated with the presence of fungi in ascitic fluid or gastroduodenal ulcer tissue but without the above-mentioned etiological factors. Thus, other factors and pathogens may be involved in the pathogenesis of perforation. The use of antifungal agents in patients following surgery for a perforated gastroduodenal ulcer is controversial. We report two cases of healthy patients who underwent surgery for perforated gastroduodenal ulcer, in whom the most frequent causes of perforation were excluded. Only the presence of Candida in the ulcer was found.

  9. [Methods for sealing of corneal perforations].

    Science.gov (United States)

    Samoilă, O; Totu, Lăcrămioara; Călugăru, M

    2012-01-01

    A variety of corneal pathology can lead to corneal ulcers and perforations. A deep corneal ulcer may need surgical treatment to allow good volume restoration and reepithelisation. Corneal perforation must be sealed and when the perforation is large, the task of repairing the defect can be underwhelming. The elegant solution is the corneal transplant, but this is not always readily available, especially in undeveloped countries. We present here two cases with different solutions to seal the perforated cornea: the first one has a large peripheral defect and it is successfully sealed with scleral patch and the second one is central with small perforation and is successfully sealed with multilayered amniotic membrane. Both cases are followed for over 12 months and demonstrate good corneal restoration (both on clinical examination and corneal topography). Sclera and amniotic membrane can be used to seal corneal defects when corneal transplant is not readily available.

  10. Intestinal perforation secondary to metastasic lung carcinoma

    Directory of Open Access Journals (Sweden)

    M. C. Álvarez Sánchez

    2014-11-01

    Full Text Available Secondary symptomatic gastrointestinal metastases from lung primary tumor are rare. They can cause a variety of clinical conditions such as perforation, obstruction and bleeding. Intestinal perforations of intestinal metastases have a very poor prognosis. We present a case of a patient with metastatic lung cancer who presents with intestinal perforation and pneumoperitoneum. A 67 year old male, immunosuppressed and smoker is diagnosed with acute abdomen secondary to perforation of a tumor of the terminal ileum, as well as three other similar injuries. Resection and anastomosis. The patient died two months after surgery. The final pathological diagnosis supports epidermoidide poorly differentiated lung carcinoma. It was concluded that given an intestinal perforation in a patient diagnosed with lung carcinoma, it shouldn´t be excluded the metastases origen . Surgery is a purely palliative procedure.

  11. Nonlinear electrostatic drift Kelvin-Helmholtz instability

    Science.gov (United States)

    Sharma, Avadhesh C.; Srivastava, Krishna M.

    1993-01-01

    Nonlinear analysis of electrostatic drift Kelvin-Helmholtz instability is performed. It is shown that the analysis leads to the propagation of the weakly nonlinear dispersive waves, and the nonlinear behavior is governed by the nonlinear Burger's equation.

  12. CHEMICAL CAUTERISATION OF TYMPANIC MEMBRANE PERFORATIONS

    Directory of Open Access Journals (Sweden)

    Vikramjit Singh

    2015-04-01

    Full Text Available Cauterisation of 144 ear perforations ( R ight and L eft with 20 percent TCA ( T richloracetic acid was tried in patients having 2 to 6mm perforations . Per forations were dry for 3 weeks - 3 months or more. 30 patients were having traumatic perforations such as slap on face, blast injuries or associated with head injuries. Most of the patients were having perforations due to inflammation. Few of them had recent attack of otitis media which were effectively treated by suitable antibiotics, anti - histamines and subs equently taken for cauterization of perforation. Site of perforation was mostly on the anteroinferior quadrant, next the inferior quadrants. Still less number in the entire four quadrant, least no. in P. S. quadrant. Traumatic perforations were irr egular i n shape varying from 2 - 6 mm in size and were elliptical in shape. Hearing loss ranged from 15dB - 45dB ( D epending upon size and site of perforation. Main presenting symptoms in inflammation cases were intermittent discharge as well as deafness. In traumatic case history of pain and deafness was the main symptom. We did wait for 1 month in traumatic cases to achieve spontaneous closure. In inflammatory cases cautery was considered first line of treatment. It has to be done several times at 10 days interval. Mo st of the times closure of perforation was achieved with 3 attempts, inflammatory cases 5 th or 6 th attempt. In one case as many as 23 attempts. In 6 cases of perforation after partial take of graft in myringoplasty occurred after 3 months cauterization was attempted and we got closure in 5 of them. In one case re myringoplasty had to be done.

  13. Global existence and asymptotic behavior for a nonlinear degenerate SIS model

    Directory of Open Access Journals (Sweden)

    Tarik Ali Ziane

    2013-01-01

    Full Text Available In this paper we investigate the global existence and asymptotic behavior of a reaction diffusion system with degenerate diffusion arising in the modeling and the spatial spread of an epidemic disease.

  14. Stochastic Dynamics and Bifurcation Behavior of Nonlinear Nonconservative Systems in the Presence of Noise

    Science.gov (United States)

    1990-08-31

    was also observed by Landsberger I and Dugundji [24] and Chen and Dugundji [25] in their experimental investigation of the aeroelastic behavior of...appear). 23. Dowell, E.H., 1975, "Aeroelasticity of Plates and Shells", Noordhoff, Leiden. 24. Landsberger, B. and Dugundji , J., 1985, "Experimental... Dugundji , J., 1987, "Experimental Aeroelastic Behavior I of Forward Swept Graphite/Epoxy Wings with Rigid-body Freedom", AIAA Journal of Aircraft, vol. 24

  15. A new model for analyzing nonlinear torsion behavior of concrete filled steel tube columns with rectangular section

    Science.gov (United States)

    Wang, Yuhang; Nie, Jianguo; Fan, Jiansheng

    2016-06-01

    An experimental study on concrete filled steel tube columns with rectangular section subjected to compressionflexure-torsion combined action has been carried out. The failure modes and load-deformation hysteretic relations were obtained. Based on the principles of classical material mechanics, the relations between the torsion curvature of the section and the shear strain of the fiber on the section were established. Then the strain distribution on the rectangular section of concrete filled steel tube columns subjected to torsion was analyzed. The three-dimensional refined finite element model was also built, in order to make the precision verification. The matrix forms of the relation between the torsion curvature of the section and the shear strain of the fiber on the section were derived, and introduced into the fiber beam model considering nonlinear torsion effect on the section. The comparison between test results and calculation results showed that the fiber beam model considering nonlinear torsion effect had high modeling efficiency and solution precision for predicting the torsion behavior of concrete filled steel tube columns with rectangular sections, and was suitable for analyzing the dynamic response of various structures subjected to the combined cyclic load caused by the earthquake load.

  16. Electronic and structural effects on the nonlinear optical behavior in push-pull TTF/tricarbonyl chromiun arene complexes.

    Science.gov (United States)

    Insuasty, Braulio; Atienza, Carmen; Seoane, Carlos; Martín, Nazario; Garín, Javier; Orduna, Jesús; Alcalá, Rafael; Villacampa, Belén

    2004-10-15

    A novel D-pi-A system in which tetrathiafulvalene (TTF) and pi-extended TTFs as strong electron donors are covalently connected to a tricarbonyl (eta(6)-arene)chromium complex as the acceptor moiety through a systematically increased conjugated bridge of vinylene units (12a-c, 16a-c) have been synthesized by Wittig-Horner olefination reaction. The electronic spectra as well as the electrochemical data reveal a different behavior of TTF derivatives (12a-c) and of exTTF derivatives (16a-c). Cyclic voltammetry shows the influence of the tricarbonylchromium arene on the oxidation potentials in compounds 12a-c, and no remarkable effect is observed for exTTFs (16a-c). The nonlinear optical properties of 12a-c and 16a-c have been calculated by using the ab initio CPHF/6-31G//B3P86/6-31G model, and the time-dependent density functional theory (TD-DFT) method has been used for the calculation of the electronic transitions. The calculations reveal that an intraligand charge-transfer transition (ILCT) and the metal to ligand charge-transfer transition (MLCT) are responsible for the nonlinear response. In addition, the large angles formed by the ground-state dipole moment and the vectorial hyperpolarizability are responsible for the mubeta values determined experimentally by the EFISH technique.

  17. Effect of the salt-induced micellar microstructure on the nonlinear shear flow behavior of ionic cetylpyridinium chloride surfactant solutions

    Science.gov (United States)

    Gaudino, D.; Pasquino, R.; Kriegs, H.; Szekely, N.; Pyckhout-Hintzen, W.; Lettinga, M. P.; Grizzuti, N.

    2017-03-01

    The shear flow dynamics of linear and branched wormlike micellar systems based on cetylpyridinium chloride and sodium salicylate in brine solution is investigated through rheometric and scattering techniques. In particular, the flow and the structural flow response are explored via velocimetry measurements and rheological and rheometric small-angle neutron scattering (SANS) experiments, respectively. Although all micellar solutions display a similar shear thinning behavior in the nonlinear regime, the experimental results show that shear banding sets in only when the micelle contour length L ¯ is sufficiently long, independent of the nature of the micellar connections (either linear or branched micelles). Using rheometric SANS, we observe that the shear banding systems both show very similar orientational ordering as a function of Weissenberg number, while the short branched micelles manifest an unexpected increase of ordering at very low Weissenberg numbers. This suggests the presence of an additional flow-induced relaxation process that is peculiar for branched systems.

  18. FINITE ELEMENT DISPLACEMENT PERTURBATION METHOD FOR GEOMETRIC NONLINEAR BEHAVIORS OF SHELLS OF REVOLUTION OVERALL BEDING IN A MERIDIONAL PLANE AND APPLICATION TO BELLOW (Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    朱卫平; 黄黔

    2002-01-01

    The finite-element-displacement-perturbation method (FEDPM)for thegeometric nonlinear behaviors of shells of revolution subjected to pure bending moments orlateral forces in one of their meridional planes ( Ⅰ ) was employed to calculate the stressdistributions and the stiffness of the bellows. Firstly, by applying the first-orderperturbation solution ( the linear solution ) of the FEDPM to the bellows, the obtainedresults were compared with those of the general solution and the initial parameter integrationsolution proposed by the present authors earlier, as well as of the experiments and the FEAby others. It is shown that the FEDPM is with good precision and reliability, and as it waspointed out in ( Ⅰ ) the abrupt changes of the meridian curvature of bellows would not affectthe use of the usual straight element. Then the nonlinear behaviors of the bellows werediscussed. As expected, the nonlinear effects mainly come from the bellows ring plate, andthe wider the ring plate is, the stronger the nonlinear effects are. Contrarily, the vanishingof the ring plate, like the C-shaped bellows, the nonlinear effects almost vanish. Inaddition, when the pure bending moments act on the bellows, each convolution has thesame stress distributions calculated by the linear solution and other linear theories, but bythe present nonlinear solution they vary with respect to the convolutions of the bellows. Yetfor most bellows, the linear solutions are valid in practice.

  19. A Distortion-Modified Free Volume Theory for Nonlinear Viscoelastic Behavior

    Science.gov (United States)

    Popelar, C. F.; Liechti, K. M.

    2003-06-01

    Many polymeric materials, including structural adhesives, exhibit anonlinear viscoelastic response. The nonlinear theory of Knauss and Emri(Polym. Engrg. Sci. 27, 1987, 87 100) is based on the Doolittle conceptthat the ‘free volume’ controls the mobility of polymer molecules and,thus, the inherent time scale of the material. It then follows thatfactors such as temperature and moisture, which change the free volume,will influence the time scale. Furthermore, stress-induced dilatationwill also affect the free volume and, hence, the time scale. However,during this investigation, dilatational effects alone were found to beinsufficient for describing the response of near pure shear tests of abisphenol A epoxy with amido amine hardener. Thus, the free volumeapproach presented here has been modified to include distortionaleffects in the inherent time scale of the material. The same was foundto be true for a urethane adhesive.

  20. Asymptotic behavior of nonlinear semigroup describing a model of selective cell growth regulation.

    Science.gov (United States)

    Arino, O; Kimmel, M

    1991-01-01

    A new scheme of regulation of cell population growth is considered, called the selective growth regulation. The principle is that cells are withdrawn from proliferation depending on their contents of certain biochemical species. The dynamics of the cell population structured by the contents of this species is described by the functional integral equation model, previously introduced by the authors. The solutions of the model equations generate a semigroup of nonlinear positive operators. The main problem solved in this paper concerns stability of the equilibria of the model. This requires stating and proving of an original abstract result on the spectral radius of a perturbation of a semigroup of positive linear operators. Biological applications are discussed.

  1. Relaxation behavior and nonlinear properties of thermally stable polymers based on glycidyl derivatives of quercetin

    Science.gov (United States)

    Mishurov, Dmytro; Voronkin, Andrii; Roshal, Alexander; Brovko, Oleksandr

    2016-07-01

    Cross-linked polymers on the basis of di-, tri and tetraglycidyl ethers of quercetin (3,3‧,4‧,5,7-pentahydroxyflavone) were synthesized, and then, poled in electrical field of corona discharge. Investigations of structural, thermal and optical parameters of the polymer films were carried out. It was found that the polymers obtained from di- and triglycidyl quercetin ethers had high values of macroscopic quadratic susceptibilities and substantial stability of nonlinear optical (NLO) properties after the poling. Tetraglycidyl ether of quercetin forms the polymer of lower quadratic susceptibility, which demonstrates noticeable relaxation process resulting in decrease of the NLO effect. It is supposed that the difference of the NLO properties is due to peculiarities of physical network of the polymers, namely to the ratio between numbers of hydrogen bonds formed by hydroxyl groups of chromophore fragments and by the ones of interfragmental parts of the polymeric chains.

  2. Influences of hydraulic gradient, surface roughness, intersecting angle, and scale effect on nonlinear flow behavior at single fracture intersections

    Science.gov (United States)

    Li, Bo; Liu, Richeng; Jiang, Yujing

    2016-07-01

    Fluid flow tests were conducted on two crossed fracture models for which the geometries of fracture segments and intersections were measured by utilizing a visualization technique using a CCD (charged coupled device) camera. Numerical simulations by solving the Navier-Stokes equations were performed to characterize the fluid flow at fracture intersections. The roles of hydraulic gradient, surface roughness, intersecting angle, and scale effect in the nonlinear fluid flow behavior through single fracture intersections were investigated. The simulation results of flow rate agreed well with the experimental results for both models. The experimental and simulation results showed that with the increment of the hydraulic gradient, the ratio of the flow rate to the hydraulic gradient, Q/J, decreases and the relative difference of Q/J between the calculation results employing the Navier-Stokes equations and the cubic law, δ, increases. When taking into account the fracture surface roughness quantified by Z2 ranging 0-0.42 for J = 1, the value of δ would increase by 0-10.3%. The influences of the intersecting angle on the normalized flow rate that represents the ratio of the flow rate in a segment to the total flow rate, Ra, and the ratio of the hydraulic aperture to the mechanical aperture, e/E, are negligible when J 10-2. Based on the regression analysis on simulation results, a mathematical expression was proposed to quantify e/E, involving variables of J and Rr, where Rr is the radius of truncating circles centered at an intersection. For E/Rr > 10-2, e/E varies significantly and the scale of model has large impacts on the nonlinear flow behavior through intersections, while for E/Rr < 10-3, the scale effect is negligibly small. Finally, a necessary condition to apply the cubic law to fluid flow through fracture intersections is suggested as J < 10-3, E/Rr < 10-3, and Z2 = 0.

  3. Viscoelasticity and nonlinear simple shear flow behavior of an entangled asymmetric exact comb polymer solution

    KAUST Repository

    Snijkers, F.

    2016-03-31

    We report upon the characterization of the steady-state shear stresses and first normal stress differences as a function of shear rate using mechanical rheometry (both with a standard cone and plate and with a cone partitioned plate) and optical rheometry (with a flow-birefringence setup) of an entangled solution of asymmetric exact combs. The combs are polybutadienes (1,4-addition) consisting of an H-skeleton with an additional off-center branch on the backbone. We chose to investigate a solution in order to obtain reliable nonlinear shear data in overlapping dynamic regions with the two different techniques. The transient measurements obtained by cone partitioned plate indicated the appearance of overshoots in both the shear stress and the first normal stress difference during start-up shear flow. Interestingly, the overshoots in the start-up normal stress difference started to occur only at rates above the inverse stretch time of the backbone, when the stretch time of the backbone was estimated in analogy with linear chains including the effects of dynamic dilution of the branches but neglecting the effects of branch point friction, in excellent agreement with the situation for linear polymers. Flow-birefringence measurements were performed in a Couette geometry, and the extracted steady-state shear and first normal stress differences were found to agree well with the mechanical data, but were limited to relatively low rates below the inverse stretch time of the backbone. Finally, the steady-state properties were found to be in good agreement with model predictions based on a nonlinear multimode tube model developed for linear polymers when the branches are treated as solvent.

  4. Numerical Simulation on New Perforator

    Institute of Scientific and Technical Information of China (English)

    姚志华; 王志军; 李德战; 付盟

    2011-01-01

    To study a new shaped charge of perforator, the jet formation and penetration processes in concrete targets are simulated numerically by using LS-DYNA finite element analysis software. The results show that the cylindrical liner can form jet and most materials on top of liner form the tip of jet, while the others form the tail of jet. The jet has a better continuity, and the ratio of cumulative jet length to the liner diameter can reach to 7.56. Furthermore, the ratio of bore diameter to the liner diameter is from 0. 36 and 1, and the ratio of penetration depth to the liner diameter can be up to 5.5.

  5. Intestinal perforation by an ingested foreign body*

    Science.gov (United States)

    Nicolodi, Gabriel Cleve; Trippia, Cesar Rodrigo; Caboclo, Maria Fernanda F. S.; de Castro, Francisco Gomes; Miller, Wagner Peitl; de Lima, Raphael Rodrigues; Tazima, Leandro; Geraldo, Jamylle

    2016-01-01

    Objective To identify the computed tomography findings suggestive of intestinal perforation by an ingested foreign body. Materials and Methods This was a retrospective study of four cases of surgically proven intestinal perforation by a foreign body, comparing the computed tomography findings with those described in the literature. Results None of the patients reported having ingested a foreign body, all were over 60 years of age, three of the four patients used a dental prosthesis, and all of the foreign bodies were elongated and sharp. In all four patients, there were findings indicative of acute abdomen. None of the foreign bodies were identified on conventional X-rays. The computed tomography findings suggestive of perforation were thickening of the intestinal walls (in all four cases), increased density of mesenteric fat (in all four cases), identification of the foreign body passing through the intestinal wall (in three cases), and gas in the peritoneal cavity (in one case). Conclusion In cases of foreign body ingestion, intestinal perforation is more common when the foreign body is elongated and sharp. Although patients typically do not report having ingested such foreign bodies, the scenario should be suspected in elderly individuals who use dental prostheses. A computed tomography scan can detect foreign bodies, locate perforations, and guide treatment. The findings that suggest perforation are thickening of the intestinal walls, increased mesenteric fat density, and, less frequently, gas in the peritoneal cavity, often restricted to the point of perforation. PMID:27818542

  6. Intestinal perforation by an ingested foreign body

    Directory of Open Access Journals (Sweden)

    Gabriel Cleve Nicolodi

    Full Text Available Abstract Objective: To identify the computed tomography findings suggestive of intestinal perforation by an ingested foreign body. Materials and Methods: This was a retrospective study of four cases of surgically proven intestinal perforation by a foreign body, comparing the computed tomography findings with those described in the literature. Results: None of the patients reported having ingested a foreign body, all were over 60 years of age, three of the four patients used a dental prosthesis, and all of the foreign bodies were elongated and sharp. In all four patients, there were findings indicative of acute abdomen. None of the foreign bodies were identified on conventional X-rays. The computed tomography findings suggestive of perforation were thickening of the intestinal walls (in all four cases, increased density of mesenteric fat (in all four cases, identification of the foreign body passing through the intestinal wall (in three cases, and gas in the peritoneal cavity (in one case. Conclusion: In cases of foreign body ingestion, intestinal perforation is more common when the foreign body is elongated and sharp. Although patients typically do not report having ingested such foreign bodies, the scenario should be suspected in elderly individuals who use dental prostheses. A computed tomography scan can detect foreign bodies, locate perforations, and guide treatment. The findings that suggest perforation are thickening of the intestinal walls, increased mesenteric fat density, and, less frequently, gas in the peritoneal cavity, often restricted to the point of perforation.

  7. Diagnosis and treatment of gallbladder perforation

    Institute of Scientific and Technical Information of China (English)

    Hayrullah Derici; Cemal Kara; Ali Dogan Bozdag; Okay Nazli; Tugrul Tansug; Esra Akca

    2006-01-01

    AIM: To present our clinical experience with gallbladder perforation cases.METHODS: Records of 332 patients who received medical and/or surgical treatment with the diagnosis of acute cholecystitis in our clinic between 1997 and 2006 were reviewed retrospectively. Sixteen (4.8%) of those patients had gallbladder perforation. The parameters including age, gender, time from the onset of symptoms to the time of surgery, diagnostic procedures, surgical treatment, morbidity, and mortality were evaluated.RESULTS: Seven patients had type Ⅰ gallbladder perforation, 7 type Ⅱ gallbladder perforation, and 2 type Ⅲ gallbladder perforation according to Niemeier's classification. The patients underwent surgery after administration of intravenous electrolyte solutions, and were treated with analgesics and antibiotics within the first 36 h (mean 9 h) after admission. Two patients died of sepsis and multiple organ failure in the early postoperative period. Subhepatic abscess, pelvic abscess,pneumonia, pancreatitis, and acute renal failure were found in 6 patients.CONCLUSION: Early diagnosis and emergency surgical treatment of gallbladder perforation are of crucial importance. Upper abdominal computerized tomography for acute cholecystitis patients may contribute to the preoperative diagnosis of gallbladder perforation.

  8. Intestinal perforation by an ingested foreign body

    Energy Technology Data Exchange (ETDEWEB)

    Nicolodi, Gabriel Cleve; Trippia, Cesar Rodrigo; Caboclo, Maria Fernanda F.S.; Castro, Francisco Gomes de; Miller, Wagner Peitl; Lima, Raphael Rodrigues de; Tazima, Leandro; Geraldo, Jamylle, E-mail: gabrielnicolodi@gmail.com [Hospital Sao Vicente - Funef, Curitiba, PR (Brazil)

    2016-09-15

    Objective: To identify the computed tomography findings suggestive of intestinal perforation by an ingested foreign body. Materials and Methods: This was a retrospective study of four cases of surgically proven intestinal perforation by a foreign body, comparing the computed tomography findings with those described in the literature. Results: None of the patients reported having ingested a foreign body, all were over 60 years of age, three of the four patients used a dental prosthesis, and all of the foreign bodies were elongated and sharp. In all four patients, there were findings indicative of acute abdomen. None of the foreign bodies were identified on conventional X-rays. The computed tomography findings suggestive of perforation were thickening of the intestinal walls (in all four cases), increased density of mesenteric fat (in all four cases), identification of the foreign body passing through the intestinal wall (in three cases), and gas in the peritoneal cavity (in one case). Conclusion: In cases of foreign body ingestion, intestinal perforation is more common when the foreign body is elongated and sharp. Although patients typically do not report having ingested such foreign bodies, the scenario should be suspected in elderly individuals who use dental prostheses. A computed tomography scan can detect foreign bodies, locate perforations, and guide treatment. The findings that suggest perforation are thickening of the intestinal walls, increased mesenteric fat density, and, less frequently, gas in the peritoneal cavity, often restricted to the point of perforation. (author)

  9. PIV study of near-field tip vortex behind perforated Gurney flaps

    Science.gov (United States)

    Lee, T.

    2011-02-01

    The impact of Gurney flaps, of different heights and perforations, on the growth and development of a tip vortex, both along the tip and in the near field of a finite NACA 0012 wing, at Re = 1.05 × 105 was investigated by using particle image velocimetry (PIV). Wind-tunnel force balance measurements were also made to supplement the PIV results. This study is a continuation of the work of Lee and Ko (Exp Fluids 46(6):1005-1019, 2009) on the near-wake measurements behind perforated Gurney flaps. The present results show that along the tip, the overall behavior of the secondary vortices and their interaction with the primary, or tip, vortex remained basically unchanged, regardless of flap height and perforation. The peak vorticity of the tip vortex, however, increased with flap height and always exhibited a local maximum at x/ c = 0.8 (from the leading edge). In the near field, the strength and structure of the near-field tip vortex were found to vary greatly with the flap height and perforation. The small flaps produced a more concentrated tip vortex with an increased circulation, while the large Gurney flaps caused a disruption of the tip vortex. The disrupted vortex can, however, be re-established by the addition of flap perforation. The larger the flap perforation the more organized the tip vortex. The Gurney flaps have the potential to serve as an alternative off-design wake vortex control device.

  10. Affective Organizational Commitment and Citizenship Behavior: Linear and Non-linear Moderating Effects of Organizational Tenure

    Science.gov (United States)

    Ng, Thomas W. H.; Feldman, Daniel C.

    2011-01-01

    Utilizing a meta-analytical approach for testing moderating effects, the current study investigated organizational tenure as a moderator in the relation between affective organizational commitment and organizational citizenship behavior (OCB). We observed that, across 40 studies (N = 11,416 respondents), the effect size for the relation between…

  11. A nonlinear dynamical systems approach to real-time teacher behavior : Differences between teachers

    NARCIS (Netherlands)

    Pennings, Helena J M; Brekelmans, Mieke; Wubbels, Theo; van der Want, Anna C.; Claessens, Luce C A; van Tartwijk, Jan

    2014-01-01

    A positive teacher-student relationship is important for students' motivation, students' academic achievement, and teacher well-being. How the teacher-student relationship develops in real-time has hardly been studied. In the present study we explored real-time interpersonal behavior (micro-level) f

  12. Affective Organizational Commitment and Citizenship Behavior: Linear and Non-linear Moderating Effects of Organizational Tenure

    Science.gov (United States)

    Ng, Thomas W. H.; Feldman, Daniel C.

    2011-01-01

    Utilizing a meta-analytical approach for testing moderating effects, the current study investigated organizational tenure as a moderator in the relation between affective organizational commitment and organizational citizenship behavior (OCB). We observed that, across 40 studies (N = 11,416 respondents), the effect size for the relation between…

  13. Experimental Study on Penetration and Perforation of Laminated Kevlar

    Institute of Scientific and Technical Information of China (English)

    王元博; 王肖钧; 胡秀章; 孙宇新

    2004-01-01

    The penetration behavior and perforation characteristics of Kevlar/Epoxy laminates with various thickness in quasi-static and ballistic perforation penetrated by steel projectiles with different noses are investigated. Quasi-static tests are conducted on MTS810 testing system. The results indicate that global deformation is the major mechanism of energy absorption and woven laminates exhibit larger energy dissipation than that of angle-plied laminates. Therefore, the woven laminates have better quasi-static penetration resistance. Ballistic tests with velocity of 200-700 m/s are executed by using a powder gun with 7.62 mm barrel. Comparing ballistic experimental results with those under quasi-static condition, both the perforation performance and the failure modes are related closely to the speed of penetrator. Quite different from quasi-static tests, ballistic tests indicate that thick angle-plied laminate targets are even better than woven laminates in resisting ballistic impact. It is observed that the damage zone of the laminate is localized highly with the increasing of the impact velocity and correspondingly, the failure modes are more manifold. The shape of projectile noses affects the impact resistance of laminated Kevlar significantly in the range of velocity around the ballistic limit.

  14. Nasal Septum Perforation due to Methamphetamine abuse

    Directory of Open Access Journals (Sweden)

    Mehdi Bakhshaee

    2012-07-01

    Full Text Available Introduction: Spontaneous Perforation of the nasal septum is an uncommon condition. Nasal inhalation of substances such as cocaine has long been linked to this Perforation. Case Report: This report describes the case of a 46-year-old woman who was addicted to methamphetamine and who presented with perforation of the nasal septum.This is the first reported case of nasal septal necrosis linked to nasal inhalation of methamphetamine. Conclusions: Patient history and assurance regardingillegal drug consumption and abuse is a key point for fast and accurate diagnosis. The pathophysiology of drug-induced sinunasal disease and a review of the literature are also presented.

  15. Perforated membrane-type acoustic metamaterials

    Science.gov (United States)

    Langfeldt, F.; Kemsies, H.; Gleine, W.; von Estorff, O.

    2017-04-01

    This letter introduces a modified design of membrane-type acoustic metamaterials (MAMs) with a ring mass and a perforation so that an airflow through the membrane is enabled. Simplified analytical investigations of the perforated MAM (PMAM) indicate that the perforation introduces a second anti-resonance, where the effective surface mass density of the PMAM is much higher than the static value. The theoretical results are validated using impedance tube measurements, indicating good agreement between the theoretical predictions and the measured data. The anti-resonances yield high low-frequency sound transmission loss values with peak values over 25 dB higher than the corresponding mass-law.

  16. Medicolegal aspects of iatrogenic root perforations

    DEFF Research Database (Denmark)

    Tsesis, I; Rosen, E; Bjørndal, L

    2014-01-01

    AIM: To retrospectively analyze the medico-legal aspects of iatrogenic root perforations (IRP) that occurred during endodontic treatments. METHODOLOGY: A comprehensive search in a professional liability insurance database was conducted to retrospectively identify cases of IRP following root canal...... treatment (p root perforation is a complication of root canal treatment and may result in tooth extraction...... and in legal actions against the treating practitioner. Mandibular molars are more prone to medico-legal claims related to root perforations. The patient should be informed of the risks during RCT and should get information on alternative treatments and their risks and prognosis...

  17. Septum nasal perforation: treatments and literature' review

    Directory of Open Access Journals (Sweden)

    Martinez Neto, Eulógio Emílio

    2010-03-01

    Full Text Available Introduction: The present study consists in a bibliographical' review concerning the articles related to the different manifestations and forms of the septum nasal perforation, with a main emphasis in the description of its techniques of surgical correction. As the etiology, that is fundamentally iatrogenic, accordingly surgical trauma. Other causes include exhibition to chemical industrial reagents, cocaine use, intranasal steroidal therapeutic, neoplasia and, infectious conditions. There is a few data concerning the prevalence of septum perforation in the general population. The decision making about surgical correction or medical treatment depend on the anatomic characteristics and of the pathogenesis of the septal perforation.

  18. Traumatic prenatal sigmoid perforation due to amniocentesis

    Energy Technology Data Exchange (ETDEWEB)

    Fines, B.; Ben-Ami, T.E.; Yousefzadeh, D.K. [Dept. of Radiology, Univ. of Chicago, IL (United States)

    2001-06-01

    A variety of fetal injuries, including those inflicted to the gastrointestinal tract by amniocentesis, have been reported before. This brief report describes the first documented case of sigmoid perforation owing to the common procedure of amniocentesis that manifested as abdominal distention at birth. A potential link between this complication and a recent increased incidence of ''intrauterine spontaneous perforation'' of the gastrointestinal tract has been mentioned. Practicing radiologists are encouraged to inquire directly about the history of amniocentesis in unexplained cases of intrauterine intestinal perforation. (orig.)

  19. Chemotaxis-fluid coupled model for swimming bacteria with nonlinear diffusion: Global existence and asymptotic behavior

    KAUST Repository

    Markowich, Peter

    2010-06-01

    We study the system ct + u · ∇c = ∇c -nf(c) nt + u · ∇n = ∇n m - ∇ · (n×(c) ∇c) ut + u·∇u + ∇P - η∇u + n∇φ/ = 0 ∇·u = 0. arising in the modelling of the motion of swimming bacteria under the effect of diffusion, oxygen-taxis and transport through an incompressible fluid. The novelty with respect to previous papers in the literature lies in the presence of nonlinear porous-medium-like diffusion in the equation for the density n of the bacteria, motivated by a finite size effect. We prove that, under the constraint m ε (3/2, 2] for the adiabatic exponent, such system features global in time solutions in two space dimensions for large data. Moreover, in the case m = 2 we prove that solutions converge to constant states in the large-time limit. The proofs rely on standard energy methods and on a basic entropy estimate which cannot be achieved in the case m = 1. The case m = 2 is very special as we can provide a Lyapounov functional. We generalize our results to the three-dimensional case and obtain a smaller range of exponents m ε (m*, 2] with m* > 3/2, due to the use of classical Sobolev inequalities.

  20. Nonlinear behavior during NO2 hydrogenation on a nanosized Pt-Rh catalyst sample

    Science.gov (United States)

    Barroo, Cédric; De Decker, Yannick; Jacobs, Luc; de Bocarmé, Thierry Visart

    2017-08-01

    Automotive pollution control crucially relies on the reactivity of metal alloy catalysts. Understanding how the chemistry of an alloy compares with that of pure metals forms a decisive step towards the rational development of applied formulations of such catalysts. In this context, we studied the hydrogenation of NO2 on Pt-Rh catalysts at the nanoscale with field emission microscopy (FEM). Previous studies have shown the presence of complex reaction kinetics at the surface of Pt for this reaction, including periodic oscillations at 390 K. As we briefly show here, similar kinetics can also be observed on Rh at higher temperatures. The alloy samples (Pt-17.4 at.%Rh) show signs of important reactivity and associated nonlinear dynamics in an intermediate temperature range. In particular, at 425 K isothermal oscillations are observed on this specific alloy catalyst. The role of the alloy composition on the window of reactivity is explained with a simple theoretical model for the kinetics of the reaction.

  1. Nonlinear optical switching behavior in the solid state: A theoretical investigation on anils

    KAUST Repository

    Ségerie, Audrey

    2011-09-13

    The linear (π(1)) and second-order nonlinear (π(2)) optical properties of two anil crystals, [N-(4-hydroxy)-salicylidene-amino-4-(methylbenzoate) and N-(3,5-di-tert- butylsalicylidene)-4-aminopyridine, denoted 4A and 4P, respectively], as well as the optical contrasts upon switching between their enol (E) and keto (K) forms, have been investigated by combining the molecular responses calculated using quantum chemistry methods and an electrostatic interaction scheme to account for the local field effects. It is found that intermolecular interactions impact differently the K/E optical contrasts in the two systems, which illustrates the importance of the supramolecular organization on the macroscopic responses. In 4A, the surrounding effects on the (hyper)polarizabilities are similar in the enol and keto forms, leading to optical contrasts very close to those of the isolated molecule. In contrast, an enhancement of the second-order susceptibility is observed in the keto form of 4P, leading to a large π(2)(K)/π(2)(E) contrast. Moreover, the π(2)(4A)/π(2)(4P) ratio for the most stable enol forms is obtained to be in good agreement with previous experimental investigations, which supports the reliability of the computational procedure. © 2011 American Chemical Society.

  2. The Impact of Perforator Number on Deep Inferior Epigastric Perforator Flap Breast Reconstruction

    Directory of Open Access Journals (Sweden)

    Ritwik Grover

    2014-01-01

    Full Text Available Background Perforator flaps minimize abdominal site morbidity during autologous breast reconstruction. The purpose of this study was to assess whether the number of perforators harvested influences the overall deep inferior epigastric perforator (DIEP flap survival and flap-related complications. Methods A retrospective review was performed of all DIEP flaps performed at the Hospital of the University of Pennsylvania from 2006 to 2011. The outcomes assessed included flap loss and major complications. We compared flaps by the number of total perforators (1-4 and then carried out a subgroup analysis comparing flaps with one perforator to flaps with multiple perforators. Lastly, we conducted a post-hoc analysis based on body mass index (BMI categorization. Results Three hundred thirty-three patients underwent 395 DIEP flaps. No significant differences were noted in the flap loss rate or the overall complications across perforator groups. However, the subgroup analysis revealed significantly higher rates of fat necrosis in the case of one-perforator flaps than in the case of multiple-perforator flaps (10.2% vs. 3.1%, P=0.009. The post-hoc analysis revealed a significant increase in the flap loss rate with increasing BMI (40=42.9%, P<0.001 in the DIEP flaps, but no increase in fat necrosis. Conclusions This study demonstrates that the number of perforators does not impact the rate of flap survival. However, the rate of fat necrosis may be significantly higher in DIEP flaps based on a single perforator. Multiple perforators should be utilized if possible to decrease the risk of fat necrosis.

  3. Nonlinear Fluctuation Behavior of Financial Time Series Model by Statistical Physics System

    Directory of Open Access Journals (Sweden)

    Wuyang Cheng

    2014-01-01

    Full Text Available We develop a random financial time series model of stock market by one of statistical physics systems, the stochastic contact interacting system. Contact process is a continuous time Markov process; one interpretation of this model is as a model for the spread of an infection, where the epidemic spreading mimics the interplay of local infections and recovery of individuals. From this financial model, we study the statistical behaviors of return time series, and the corresponding behaviors of returns for Shanghai Stock Exchange Composite Index (SSECI and Hang Seng Index (HSI are also comparatively studied. Further, we investigate the Zipf distribution and multifractal phenomenon of returns and price changes. Zipf analysis and MF-DFA analysis are applied to investigate the natures of fluctuations for the stock market.

  4. SIMULATION OF COMPOSITE NON-LINEAR MECHANICAL BEHAVIOR OF CMCS BY FEM-BASED MULTI-SCALE APPROACH

    Institute of Scientific and Technical Information of China (English)

    高希光; 王绍华; 宋迎东

    2013-01-01

    The non-linear behavior of continuous fiber reinforced C/SiC ceramic matrix composites (CMCs) under tensile loading is modeled by three-dimensional representative volume element (RVE) models of the composite . The theoretical background of the multi-scale approach solved by the finite element method (FEM ) is recalled first-ly .Then the geometric characters of three kinds of damage mechanisms ,i .e .micro matrix cracks ,fiber/matrix interface debonding and fiber fracture ,are studied .Three kinds of RVE are proposed to model the microstructure of C/SiC with above damage mechanisms respectively .The matrix cracking is modeled by critical matrix strain en-ergy (CMSE) principle while a maximum shear stress criterion is used for modeling fiber/matrix interface debond-ing .The behavior of fiber fracture is modeled by the famous Weibull statistic theory .A numerical example of con-tinuous fiber reinforced C/SiC composite under tensile loading is performed .The results show that the stress/strain curve predicted by the developed model agrees with experimental data .

  5. Variational principles for linear and nonlinear mixtures: New derivations and application to bilinear materials and yield behavior

    Science.gov (United States)

    Alqaraleh, Sahar Mubarak

    2006-04-01

    We study in this paper the effective energy potential of nonlinear composites in terms of the corresponding energy potential for linear material. We study this for power law material using Suquet's variational principle, for bilinear material using Ponte Castaneda variational principle, and we studied the yield behavior as limiting cases of both. We show that three established variational principles can be derived from the Cauchy-Buniakowski-Schwartz inequality; these variational principles (bounds) are: (a) bounds on yield behavior of mixtures, (b) The Hashin-Shtrikman variational principle for linear materials, (c) The Debotton and Ponte Castaneda bound for power-law polycrystals. We also compute the actual stress and strain fields for laminate material for two choices of the average strain, and compute a bound on the effective potential for spherical inclusions using Hashin's linear bound, as well as for spheroidal inclusions using Willis's linear bound. We obtained bounds sharper than the established bounds for both laminate and aligned ellipsoids geometry, and we investigate also how the bound depends on the specified geometry and on specific parameters of the problem.

  6. Effect of Perforation Area and Arrangement Pattern on Structural Behaviour of Nature Inspired Perforated Hollow Structure

    Directory of Open Access Journals (Sweden)

    Woo Yian Peen

    2013-01-01

    Full Text Available The Cholla cactus skeleton has been the inspiration source for this study, in our effort to search forlight and more structural effective structures. This woody skeleton of Cholla with oval shaped perforationsarranged in spiral pattern is found strong enough to support the cactus self weight. This research has beencarried out to investigate the effects of percentage of perforations and perforations arrangements on structuralbehaviour of cylindrical hollow section. A total of eleven models consisting of one cylindrical hollow sectionwithout perforation as the control model and ten simplified perforated cylindrical hollow sections have beenconstructed using a finite element method software. The perforated models have been assigned with 10 to 50percent of perforations area by fixing the number of perforations to twenty and altering the perforation size toachieve the percentage variable. Computational analyses have been carried out for three loading conditions:compressive, flexural and torsional. Findings have shown that the increment in percentage of perforationsproduces higher stresses to the cylindrical hollow section. This has effects on the structural capacity of thecylindrical hollow section. Array arrangement of the perforations shows better structural performance incompression and flexural loading conditions while spiral arrangement exhibits better structural performanceunder torsional loading condition.

  7. Stercoral perforation in a 17-year old.

    LENUS (Irish Health Repository)

    McHugh, S

    2012-02-01

    INTRODUCTION: Stercoral perforation is a rare cause of perforation. This is the first reported case where a partial eating disorder (ED) is the primary causative differential. CASE PRESENTATION: We present the case of a 17-year-old girl who presented to her local Emergency Department with a 24-h history of left-sided abdominal pain. She subsequently deteriorated and a computed tomography scan of her abdomen showed gross distension of the large bowel with a sigmoid perforation. She underwent total colectomy with end ileostomy. Histology reported stercoral perforation but normal bowel ganglia. While an inpatient she was reviewed by the Psychiatric team who were concerned she was suffering from a partial ED. CONCLUSION: This case highlights the importance of a multidisciplinary approach in optimally treating patients such as these. Aggressive medical management with involvement of a psychiatric team and dietetics addresses any underlying causative psychiatric issues and helps prevent recurrence.

  8. Typhoid intestinal perforation in North Central Nigeria

    African Journals Online (AJOL)

    children than adults and associated with perforation-surgery interval of between ... gations, surgical options employed and management outcome ... (ICU) after surgery. Oral feeds ... Clinical features: Fever and abdominal pain were common.

  9. Laparoscopic Repair for Perforated Duodenal Ulcer

    Directory of Open Access Journals (Sweden)

    A. Cotirleţ

    2015-01-01

    Full Text Available Perforated peptic ulcer (PPU, despite antiulcer medication and Helicobacter eradication, is still the most common indication for emergency gastric surgery associated with high morbidity and mortality. Perforated peptic ulcer is a common abdominal disease that is treated by surgery. The development of laparoscopic surgery has changed the way to treat such abdominal surgical emergencies but there is no consensus on whether the benefits of laparoscopic closure of perforated peptic ulcer outweigh the disadvantages such as prolonged surgery time and greater expense. However we can say that laparoscopic repair is a viable and safe surgical option for patients with perforated peptic ulcer disease and should be considered with the necessary expertise available.

  10. Stercoral perforation in a 17-year old.

    LENUS (Irish Health Repository)

    McHugh, S

    2009-04-02

    INTRODUCTION: Stercoral perforation is a rare cause of perforation. This is the first reported case where a partial eating disorder (ED) is the primary causative differential. CASE PRESENTATION: We present the case of a 17-year-old girl who presented to her local Emergency Department with a 24-h history of left-sided abdominal pain. She subsequently deteriorated and a computed tomography scan of her abdomen showed gross distension of the large bowel with a sigmoid perforation. She underwent total colectomy with end ileostomy. Histology reported stercoral perforation but normal bowel ganglia. While an inpatient she was reviewed by the Psychiatric team who were concerned she was suffering from a partial ED. CONCLUSION: This case highlights the importance of a multidisciplinary approach in optimally treating patients such as these. Aggressive medical management with involvement of a psychiatric team and dietetics addresses any underlying causative psychiatric issues and helps prevent recurrence.

  11. Diagnosis and management of iatrogenic endoscopic perforations

    DEFF Research Database (Denmark)

    Paspatis, Gregorios A; Dumonceau, Jean-Marc; Barthet, Marc

    2014-01-01

    This Position Paper is an official statement of the European Society of Gastrointestinal Endoscopy (ESGE). It addresses the diagnosis and management of iatrogenic perforation occurring during diagnostic or therapeutic digestive endoscopic procedures. Main recommendations 1 ESGE recommends that each...... center implements a written policy regarding the management of iatrogenic perforation, including the definition of procedures that carry a high risk of this complication. This policy should be shared with the radiologists and surgeons at each center. 2 In the case of an endoscopically identified...... perforation after an endoscopic procedure should be carefully evaluated and documented, possibly with a computed tomography (CT) scan, in order to prevent any diagnostic delay. 4 ESGE recommends that endoscopic closure should be considered depending on the type of perforation, its size, and the endoscopist...

  12. Perforated peptic ulcer: How to improve outcome?

    DEFF Research Database (Denmark)

    Møller, Morten Hylander; Adamsen, Sven; Wøjdemann, Morten;

    2008-01-01

    Despite the introduction of histamine H(2)-receptor antagonists, proton-pump inhibitors and the discovery of Helicobacter pylori, both the incidence of emergency surgery for perforated peptic ulcer and the mortality rate for patients undergoing surgery for peptic ulcer perforation have increased...... with an emphasis on risks that are preventable. A systematic review including randomized studies was carried out. There are a limited number of studies of patients with peptic ulcer perforation. Most of these studies are of low evidential status. Only a few randomized, controlled trials have been published...... to improve the outcome of patients with peptic ulcer perforation, sepsis needs to be factored into the existing knowledge and treatment Udgivelsesdato: 2008/8/27...

  13. Effects of nonlinearity in the materials used for the semi-rigid pedicle screw systems on biomechanical behaviors of the lumbar spine after surgery

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun; Lee, Sung-Jae [Department of Biomedical Engineering, Inje University, Gimhae 621749 (Korea, Republic of); Lim, Do-Hyung [Korea Institute of Industrial Technology, Cheonan 331825 (Korea, Republic of); Oh, Hyun-Ju [Korea Food and Drug Administration, Seoul 363951 (Korea, Republic of); Lee, Kwon-Yong, E-mail: sjl@bme.inje.ac.kr [Department of Mechanical Engineering, Sejong University, Seoul 143747 (Korea, Republic of)

    2011-10-15

    Recently, various types of semi-rigid pedicle screw fixation systems have been developed for the surgical treatment of the lumbar spine. They were introduced to address the adverse issues commonly found in traditional rigid spinal fusion--abnormally large motion at the adjacent level and subsequent degeneration. The semi-rigid system uses more compliant materials (nitinol or polymers) and/or changes in rod design (coiled or twisted rods) as compared to the conventional rigid straight rods made of Ti alloys (E = 114 GPa, {upsilon} = 0.32). However, biomechanical studies on the semi-rigid pedicle screw systems were usually limited to linear modeling of the implant and anatomic elements, which may not be capable of reflecting realistic post-operative motions of the spine. In this study, we evaluated the effects of nonlinearity in materials used for semi-rigid pedicle screw fixation systems to evaluate the changes in biomechanical behaviors using finite element analysis. Changes in range of motion (ROM) and center of rotation (COR) were assessed at the operated and adjacent levels. Actual load-displacement results of the semi-rigid rod from mechanical test were carried out to reflect the nonlinearity of the implant. In addition, nonlinear material properties of various spinal ligaments studies were used for the finite element modeling. The post-operative models were constructed by modifying the previously validated intact model of the L1-S1 spine. Eight different post-operative models were made to address the effects of nonlinearity-with a traditional stiffness modulus rod (with linear ligaments, case 1; with nonlinear ligaments, case 5), with a rigid rod (with linear ligaments, case 2; with nonlinear ligaments, case 6), with a soft rod (with linear ligaments, case 3; with nonlinear ligaments, case 7), and with a nonlinear rod (with linear ligaments, case 4; with nonlinear ligaments, case 8). To simulate the load on the lumbar spine in a neutral posture, follower load

  14. Gall bladder perforation in acalculous cholecystitis

    OpenAIRE

    Dayananda Srinivasan; Sujith Sherigar; Durganna Thimmappa

    2014-01-01

    Acute acalculous cholecystitis is relatively rare as compared to the calculous cholecystitis. But complications like gangrenous changes and Gall bladder (GB) perforation is more common with acalculous variety than calculous cholecystitis.GB perforation following acalculous cholecystitis has a mortality of 10-50 % as compared to that of 1% following calculous cholecystitis. The literarature pertaining to this is very few and does not conclude a standard mangement in such cases. ...

  15. Freestyle Local Perforator Flaps for Facial Reconstruction

    OpenAIRE

    Jun Yong Lee; Ji Min Kim; Ho Kwon; Sung-No Jung; Hyung Sup Shim; Sang Wha Kim

    2015-01-01

    For the successful reconstruction of facial defects, various perforator flaps have been used in single-stage surgery, where tissues are moved to adjacent defect sites. Our group successfully performed perforator flap surgery on 17 patients with small to moderate facial defects that affected the functional and aesthetic features of their faces. Of four complicated cases, three developed venous congestion, which resolved in the subacute postoperative period, and one patient with partial necrosi...

  16. Modeling Topology and Nonlinear Dynamical Behavior of the Weighted Scale-Free Networks

    Institute of Scientific and Technical Information of China (English)

    YANG Qiu-Ying; ZHANG Gui-Qing; ZHANG Ying-Yue; CHEN Tian-Lun

    2008-01-01

    An improved weighted scale-free network,which has two evolution mechanisms:topological growth and strength dynamics,has been introduced.The topology structure of the model will be explored in details in this work.The evolution driven mechanism of Olami-Feder-Christensen (OFC) model is added to our model to study the self-organized criticality and the dynamical behavior.We also.consider attack mechanism and the study of the model with attack is also investigated in this paper.We find there axe differences between the model with attack and without attack.

  17. Non-linear magnetic behavior around zero field of an assembly of superparamagnetic nanoparticles.

    Science.gov (United States)

    de Montferrand, Caroline; Lalatonne, Yoann; Bonnin, Dominique; Motte, Laurence; Monod, Philippe

    2012-05-21

    The MIAplex® device is a miniaturized detector, devoted to the high sensitive detection of superparamagnetic nanoprobes for multiparametric immunoassays. It measures a signal corresponding to the second derivative of the magnetization around zero field. Like any new technology, the real success of the MIAplex® detector can only be exploited through a deep understanding of the magnetic signature. In this letter, we study the magnetic behavior around zero-field of diluted lab-made and commercial ferrofluids by comparing together conventional SQUID magnetization and MIAplex® signature.

  18. Asymptotic behavior of solutions for some nonlinear partial differential equations on unbounded domains

    Directory of Open Access Journals (Sweden)

    Jacqueline Fleckinger

    2001-12-01

    Full Text Available We study the asymptotic behavior of positive solutions $u$ of $$ -Delta_p u(x = V(x u(x^{p-1}, quad p>1; x in Omega,$$ and related partial differential inequalities, as well as conditions for existence of such solutions. Here, $Omega$ contains the exterior of a ball in $mathbb{R}^N$ $1

  19. Dynamic nonlinear feedback for temperature control of continuous stirred reactor with complex behavior

    Directory of Open Access Journals (Sweden)

    Pablo A. López Pérez

    2009-08-01

    Full Text Available The main objective of this work is to present an alternative methodology for the design of a class of integral high order slidingmodecontroller applied to a class of continuous chemical reactor with complex behavior for temperature tracking purposes.The proposed design is based on the differential geometry framework, where the named reaching trajectory contains a highorder sliding mode term in order to diminish chattering. Considering that the proposed technique is model based, an observerbaseduncertainty estimator is coupled, which provides robustness against model uncertainties and noisy measurements.Numerical simulations are performed in order to show the capacities of the proposed controller, which is compared with othernonlinear methodologies.

  20. Nonlinear photonic diode behavior in energy-graded core-shell quantum well semiconductor rod.

    Science.gov (United States)

    Ko, Suk-Min; Gong, Su-Hyun; Cho, Yong-Hoon

    2014-09-10

    Future technologies require faster data transfer and processing with lower loss. A photonic diode could be an attractive alternative to the present Si-based electronic diode for rapid optical signal processing and communication. Here, we report highly asymmetric photonic diode behavior with low scattering loss, from tapered core-shell quantum well semiconductor rods that were fabricated to have a large gradient in their bandgap energy along their growth direction. Local laser illumination of the core-shell quantum well rods yielded a huge contrast in light output intensities from opposite ends of the rod.

  1. Surgical treatment of perforated gastric ulcer

    Directory of Open Access Journals (Sweden)

    Korica Milan

    2002-01-01

    Full Text Available Introduction Peptic ulcer perforation is a complication of ulcer disease which requires urgent surgical treatment. The aim of this paper was to point out our experience in surgical treatment of perforated peptic ulcer. Material and methods This retrospective study analyzes results of surgical treatment in 365 patients with perforated peptic ulcer during the period January 1996 to December 2000. Results During the last 5-year period 365 patients were treated following peptic ulcer perforation. The average age was 43.53±8.26, with the span from 18 to 86. The most frequent surgical procedures in treatment of peptic ulcer perforation were: simple closure with biopsy (55.88%, excision of the ulcer with a pyloroplasty and vagotomy (35.29% as nonresection surgical procedures and stomach resection after Billroth II (8.83%. The postoperative mortality was 4.41%. Conclusions The methods of choice in surgical treatment of gastric ulcer perforation are nonresection surgical procedures with drug therapy and eradication of Helicobacter pylori, if present.

  2. Perforated duodenal ulcer in Asir central hospital

    Directory of Open Access Journals (Sweden)

    Jastaniah Suleiman

    1997-01-01

    Full Text Available In a study of 27 cases of perforated duodenal ulcer seen at Asir Central Hospital over a period of seven years, two patients were females and 25 males. The highest incidence was in the fourth decade and the average age was 36.3 years. The Saudi-foreigner ratio was 1:2.9 in an area where the Saudi-foreigner population ratio was 1:3. Nine patients (33.3% were previously diagnosed as having peptic ulcer and had received treatment at one time or the other before perforation. Eighteen patients (66.7% were first diagnosed to peptic ulcer after the perforation. All the identified perforations were located anteriorly and anterosuperiorly. Only one case occurred in the second part of duodenum. The rest occurred in the first part. Two patients were treated successfully conservatively. The month perforations occurred most was the month of Shaaban. The fasting period during the month of Ramadhan did not show any increase in the prevalence of perforation in this hospital.

  3. Ventriculoperitoneal shunt perforations of the gastrointestinal tract.

    Science.gov (United States)

    Thiong'o, Grace Muthoni; Luzzio, Christopher; Albright, A Leland

    2015-07-01

    OBJECT The purposes of this study were to evaluate the frequency with which children presented with ventriculoperitoneal (VP) shunt perforations of the gastrointestinal (GI) tract, to determine the type of shunts that caused the perforations, and to compare the stiffness of perforating catheters with the stiffness of catheters from other manufacturers. METHODS Medical records were reviewed of 197 children who were admitted with VP shunt malfunction. Catheter stiffness was evaluated by measuring relative resistance to cross-sectional compression, resistance to column buckling, and elasticity in longitudinal bending. Catheter frictional force was measured per unit length. RESULTS Six children were identified whose VP shunts had perforated the GI tract; 2 shunts subsequently protruded through the anal orifice, 1 protruded through the oral cavity, and 3 presented with subcutaneous abscesses that tracked upward from the intestine to the chest. All perforating shunts were Chhabra shunts. Catheter stiffness and resistance to bending were greatest with a Medtronic shunt catheter, intermediate with a Codman catheter, and least with a Chhabra catheter. Frictional force was greatest with a Chhabra catheter and least with a Medtronic catheter. CONCLUSIONS The frequency of perforations by Chhabra shunts appears to be higher than the frequency associated with other shunts. The increased frequency does not correlate with their stiffness but may reflect their greater frictional forces.

  4. Fat graft myringoplasty in small central perforations

    Directory of Open Access Journals (Sweden)

    Chandni Sharma

    2014-01-01

    Full Text Available Background: Perforations of the tympanic membrane (TM are treated with various surgical techniques and materials. Although autologous temporalis fascia is the most common material used for the closure of TM perforations, however for a dry, small central perforation the fat graft myringoplasty (FM is a good alternative as it is a simple and cost-effective technique. Objectives: The aim of this study was to determine the efficacy of FM for repair of small central perforations. Suggestions for optimizing the outcome of FM are presented. Material and Methods: Twenty patients (10 males and 10 females who had uncomplicated dry small central perforation, which was confined to one quadrant of the pars tensa underwent FM. The outcome was evaluated after 1-week, 1-month, and 3 months. Results: After 3 months of follow-up, a closure rate of 80% was achieved. Mean preoperative air-bone (AB gap was 22.90 ± 6.54 dB and mean postoperative AB gap was 21.80 ± 6.28 dB. Mean improvement in AB gap postoperatively was 1.1 ± 2.63 dB. Conclusion: Fat graft myringoplasty, with its ease of technique and good graft uptake rate justifies its use in the closure of small dry central TM perforations.

  5. Quantitative analysis of the nonlinear displacement-load behavior of the lumbar spine.

    Science.gov (United States)

    Hanlon, Andrew D; Cook, Daniel J; Yeager, Matthew S; Cheng, Boyle C

    2014-08-01

    There is currently no universal model or fitting method to characterize the visco-elastic behavior of the lumbar spine observed in displacement versus load hysteresis loops. In this study, proposed methods for fitting these loops, along with the metrics obtained, were thoroughly analyzed. A spline fitting technique was shown to provide a consistent approximation of spinal kinetic behavior that can be differentiated and integrated. Using this tool, previously established metrics were analyzed using data from two separate studies evaluating different motion preservation technologies. Many of the metrics, however, provided no significant differences beyond range of motion analysis. Particular attention was paid to how different definitions of the neutral zone capture the high-flexibility region often seen in lumbar hysteresis loops. As a result, the maximum slope was introduced and shown to be well defined. This new parameter offers promise as a descriptive measurement of spinal instability in vitro and may have future implications in clinical diagnosis and treatment of spinal instability. In particular, it could help in assigning treatments to specific stabilizing effects in the lumbar spine.

  6. EXISTENCE AND ASYMPTOTIC BEHAVIOR OF THE SOLUTIONS FOR A NONLINEAR ELLIPTIC EQUATION ARISING IN ASTROPHYSICS

    Institute of Scientific and Technical Information of China (English)

    Tang Zhongwei

    2006-01-01

    The author first analyzes the existence of ground state solutions and cylindrically symmetric solutions and then the asymptotic behavior of the ground state solution of the equation -Au = φ(r)up-1, u > 0 in RN, u ∈ D1,2(RN), where N ≥ 3, x =(x',z) ∈ RK × RN-K,2 ≤ K ≤ N,r = |x'|. It is proved that for 2(N-s)/(N-2) <p < 2* = 2N/(N - 2), 0 < s < 2, the above equation has a ground state solution and a cylindrically symmetric solution. For p = 2*, the above equation does not have a ground state solution but a cylindrically symmetric.solution, and when p close to 2*, the ground state solutions are not cylindrically symmetric. On the other hand, it is proved that as p close to 2*, the ground state solution up has a unique maximum point xp = (x'p, zp) and as p → 2*, |x'p| → r0 which attains the maximum of φ on RN. The asymptotic behavior ofground state solution up is also given, which also deduces that the ground state solutionis not cylindrically symmetric as p goes to 2*.

  7. Mixed and Penalty Finite Element Models for the Nonlinear Behavior of Biphasic Soft Tissues in Finite Deformation: Part II - Nonlinear Examples.

    Science.gov (United States)

    Almeida, EDGARD S.; Spilker, ROBERT L.

    1998-01-01

    This two-part paper addresses finite element-based computational models for the three-dimensional (3-D) nonlinear analysis of soft hydrated tissues, such as articular cartilage in diarthrodial joints, under physiologically relevant loading conditions. A biphasic continuum description is used to represent the soft tissue as a two-phase mixture of incompressible inviscid fluid and a hyperelastic, transversely isotropic solid. Alternate mixed-penalty and velocity-pressure finite element formulations are used to solve the nonlinear biphasic governing equations, including the effects of strain-dependent permeability and a hyperelastic solid phase under finite deformation. The resulting first-order, nonlinear system of equations is discretized in time using an implicit finite difference scheme, and solved using the Newton-Raphson method. Details of the formulations were presented in Part I [1]. In Part II, the two formulations are used to develop two-dimensional (2-D) quadrilateral and triangular elements and three-dimensional (3-D) hexahedral and tetrahedral elements. Numerical examples, including those representative of soft tissue material testing and simple human joints, are used to validate the formulations and to illustrate their applications. A focus of this work is the comparison of the alternate formulations for nonlinear problems. While it is demonstrated that both formulations produce a range of converging elements, the velocity-pressure formulation is found to be more efficient computationally.

  8. Identification of Nonlinear Dynamic Behavior and Failure for Riveted Joint Assemblies

    Directory of Open Access Journals (Sweden)

    B. Langrand

    2000-01-01

    Full Text Available Many different types of rivets need to be modeled to analyze the crashworthiness of aircraft structures. A numerical procedure based on FE modeling and characterization of material failure constitutive models is proposed herein with the aim of limiting the costs of experimental procedures otherwise necessary to obtain these data. Quasi-static and dynamic experiments were carried out on elementary tension (punched and shear (riveted specimens. No strain rate sensitivity was detected in the failure behavior of the riveted joint assemblies. Experimental data were used to identify the Gurson damage parameters of each material (2024-T351 and 7050 aluminum alloys for the sheet metal plate and the rivet respectively by an inverse method. Characterization gave rise to satisfactory correlation between FE models and experiments. Optimized parameters were validated for each material by means of a uniaxial tension test for the sheet metal plate and an ARCAN type specimen in pure tension for the rivet.

  9. Spectrum of perforation peritonitis in Pakistan: 300 cases Eastern experience

    Directory of Open Access Journals (Sweden)

    Ur-Rahman Shafiq

    2008-11-01

    Full Text Available Abstract Background Perforation peritonitis is the most common surgical emergency encountered by the surgeons all over the world as well in Pakistan. The spectrum of etiology of perforation peritonitis in tropical countries continues to differ from its western counter part. This study was conducted at Dow University of health sciences and Civil Hospital Karachi (DUHS & CHK Pakistan, designed to highlight the spectrum of perforation peritonitis in the East and to improve its outcome. Methods A prospective study includes three hundred consecutive patients of perforation peritonitis studied in terms of clinical presentations, Causes, site of perforation, surgical treatment, post operative complications and mortality, at (DUHS&CHK Pakistan, from 1st September 2005 – 1st March 2008, over a period of two and half years. All patients were resuscitated underwent emergency exploratory laparotomy. On laparotomy cause of perforation peritonitis was found and controlled. Results The most common cause of perforation peritonitis noticed in our series was acid peptic disease 45%, perforated duodenal ulcer (43.6% and gastric ulcer 1.3%. followed by small bowel tuberculosis (21% and typhoid (17%. large bowel perforation due to tuberculosis 5%, malignancy 2.6% and volvulus 0.3%. Perforation due to acute appendicitis (5%. Highest number of perforations has seen in the duodenum 43.6%, ileum37.6%, and colon 8%, appendix 5%, jejunum 3.3%, and stomach 2.3%. Overall mortality was (10.6%. Conclusion The spectrum of perforation peritonitis in Pakistan continuously differs from western country. Highest number of perforations noticed in the upper part of the gastrointestinal tract as compared to the western countries where the perforations seen mostly in the distal part. Most common cause of perforation peritonitis is perforated duodenal ulcer, followed by small bowel tuberculosis and typhoid perforation. Majority of the large bowel perforations are also tubercular

  10. Differentiation of Acute Perforated from Non-Perforated Appendicitis: Usefulness of High-Resolution Ultrasonography

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Gyu Chang [Dept. of Radiology, Gumi Hospital, Soonchunhyang University College of Medicine, Gumi (Korea, Republic of)

    2011-07-15

    To evaluate the usefulness of high-resolution ultrasonography (US) for the differentiation of acute perforated appendicitis from non-perforated appendicitis. The high-resolution US features in 96 patients (49 males, 47 females; mean age, 33.8 years; age range, 4-80 years) with pathologically proven acute appendicitis were evaluated. The following US findings were evaluated for differentiation of acute perforated appendicitis from non-perforated appendicitis: circumferential loss of the echogenic submucosal layer, periappendiceal fluid collection, disruption of the serosal layer, asymmetrical wall thickening, maximum overall diameter > 10.5 mm, and the presence of appendicoliths. The sensitivity and specificity of the US features in the diagnosis of acute perforated appendicitis were calculated. All of the US findings, except for appendicoliths, were significantly more common in the acute perforated appendicitis group (p < 0.001). The sensitivity of circumferential loss of the echogenic submucosal layer, periappendiceal fluid collection, disruption of the serosal layer, asymmetrical wall thickening, maximum overall diameter > 10.5 mm, and the presence of appendicoliths was 85.4, 73.2, 68.3, 70.7, 80.5, and 36.6%, respectively, while the specificity was 65.5, 89.1, 96.4, 98.2, 81.8, and 80.0%, respectively. High-resolution US was found to be useful for differentiating acute perforated appendicitis from non-perforated appendicitis.

  11. Gastrointestinal tract perforation: evaluation of MDCT according to perforation site and elapsed time

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun Cheol; Yang, Dal Mo; Kim, Sang Won [Kyung Hee University Hospital at Gangdong, College of Medicine, Kyung Hee University, Department of Radiology, Seoul (Korea, Republic of); Park, Seong Jin [Kyung Hee University Hospital, College of Medicine, Kyung Hee University, Department of Radiology, Seoul (Korea, Republic of)

    2014-06-15

    To evaluate mutidetector computed tomography (MDCT) for the prediction of perforation site according to each gastrointestinal (GI) tract site and elapsed time. One hundred and sixty-eight patients who underwent MDCT before laparotomy for GI tract perforation were enrolled and allocated to an early or late lapse group based on an elapsed time of 7 h. Two reviewers independently evaluated the perforation site and assessed the following CT findings: free air location, mottled extraluminal air bubbles, focal bowel wall discontinuity, segmental bowel wall thickening, perivisceral fat stranding and localised fluid collection. The overall diagnostic accuracy was 91.07 % and 91.67 % for reviewers 1 and 2, respectively, with excellent agreement (kappa 0.86). Accuracies (98.97 % and 97.94 %) and agreements (kappa 0.894) for stomach and duodenum perforation were higher than for other perforation sites. Strong predictors of perforation at each site were: focal bowel wall discontinuity for stomach, duodenal bulb and left colon, mottled extraluminal air bubbles for retroperitoneal duodenum and right colon, and segmental bowel wall thickening for small bowel. The diagnostic accuracy was not different between the early- and late-lapse groups. MDCT can accurately predict upper GI tract perforation with high reliability. Elapsed time did not affect the accuracy of perforation site prediction. (orig.)

  12. Coronary perforation and covered stents: An update and review

    Directory of Open Access Journals (Sweden)

    Mohammed Al-Mukhaini

    2011-01-01

    Full Text Available Coronary perforation is a rare complication of percutaneous coronary intervention. We present two different types of coronary intervention, but both ending with coronary perforation. However, these perforations were tackled successfully by covered stents. This article reviews the incidence, causes, presentation, and management of coronary perforation in the present era of aggressive interventional cardiology. Coronary perforations are classified as type I (extraluminal crater, II (myocardial or pericardial blushing, and III (contrast streaming or cavity spilling. Types I and II coronary perforations are caused by stiff or hydrophilic guidewires. Type I has a benign prognosis, whereas type II coronary perforations have the potential to progress to tamponade. Type III coronary perforations are caused by balloons, stents, or other intracoronary devices and commonly lead to cardiac tamponade necessitating pericardial drainage. However, type III perforations can be managed with covered stents without need for surgical intervention.

  13. Investigation of hyperelastic models for nonlinear elastic behavior of demineralized and deproteinized bovine cortical femur bone.

    Science.gov (United States)

    Hosseinzadeh, M; Ghoreishi, M; Narooei, K

    2016-06-01

    In this study, the hyperelastic models of demineralized and deproteinized bovine cortical femur bone were investigated and appropriate models were developed. Using uniaxial compression test data, the strain energy versus stretch was calculated and the appropriate hyperelastic strain energy functions were fitted on data in order to calculate the material parameters. To obtain the mechanical behavior in other loading conditions, the hyperelastic strain energy equations were investigated for pure shear and equi-biaxial tension loadings. The results showed the Mooney-Rivlin and Ogden models cannot predict the mechanical response of demineralized and deproteinized bovine cortical femur bone accurately, while the general exponential-exponential and general exponential-power law models have a good agreement with the experimental results. To investigate the sensitivity of the hyperelastic models, a variation of 10% in material parameters was performed and the results indicated an acceptable stability for the general exponential-exponential and general exponential-power law models. Finally, the uniaxial tension and compression of cortical femur bone were studied using the finite element method in VUMAT user subroutine of ABAQUS software and the computed stress-stretch curves were shown a good agreement with the experimental data.

  14. Nonlinear Approaches in Engineering Applications

    CERN Document Server

    Jazar, Reza

    2012-01-01

    Nonlinear Approaches in Engineering Applications focuses on nonlinear phenomena that are common in the engineering field. The nonlinear approaches described in this book provide a sound theoretical base and practical tools to design and analyze engineering systems with high efficiency and accuracy and with less energy and downtime. Presented here are nonlinear approaches in areas such as dynamic systems, optimal control and approaches in nonlinear dynamics and acoustics. Coverage encompasses a wide range of applications and fields including mathematical modeling and nonlinear behavior as applied to microresonators, nanotechnologies, nonlinear behavior in soil erosion,nonlinear population dynamics, and optimization in reducing vibration and noise as well as vibration in triple-walled carbon nanotubes. This book also: Provides a complete introduction to nonlinear behavior of systems and the advantages of nonlinearity as a tool for solving engineering problems Includes applications and examples drawn from the el...

  15. Nonlinear Surface Dilatational Rheology and Foaming Behavior of Protein and Protein Fibrillar Aggregates in the Presence of Natural Surfactant.

    Science.gov (United States)

    Wan, Zhili; Yang, Xiaoquan; Sagis, Leonard M C

    2016-04-19

    The surface and foaming properties of native soy glycinin (11S) and its heat-induced fibrillar aggregates, in the presence of natural surfactant steviol glycoside (STE), were investigated and compared at pH 7.0 to determine the impact of protein structure modification on protein-surfactant interfacial interactions. The adsorption at, and nonlinear dilatational rheological behavior of, the air-water interface were studied by combining drop shape analysis tensiometry, ellipsometry, and large-amplitude oscillatory dilatational rheology. Lissajous plots of surface pressure versus deformation were used to analyze the surface rheological response in terms of interfacial microstructure. The heat treatment generates a mixture of long fibrils and unconverted peptides. The presence of small peptides in 11S fibril samples resulted in a faster adsorption kinetics than that of native 11S. The addition of STE affected the adsorption of 11S significantly, whereas no apparent effect on the adsorption of the 11S fibril-peptide system was observed. The rheological response of interfaces stabilized by 11S-STE mixtures also differed significantly from the response for 11S fibril-peptide-STE mixtures. For 11S, the STE reduces the degree of strain hardening in extension and increases strain hardening in compression, suggesting the interfacial structure may change from a surface gel to a mixed phase of protein patches and STE domains. The foams generated from the mixtures displayed comparable foam stability to that of pure 11S. For 11S fibril-peptide mixtures STE only significantly affects the response in extension, where the degree of strain softening is decreased compared to the pure fibril-peptide system. The foam stability of the fibril-peptide system was significantly reduced by STE. These findings indicate that fibrillization of globular proteins could be a potential strategy to modify the complex surface and foaming behaviors of protein-surfactant mixtures.

  16. Case Report: Delayed Perforation after Definitive Treatment of Focal Intestinal Perforation with a Peritoneal Drain

    Directory of Open Access Journals (Sweden)

    Brian G. A. Dalton

    2012-01-01

    Full Text Available Focal intestinal perforation (FIP has long been described in the pediatric literature. Peritoneal drainage (PD is widely used as treatment for focal intestinal perforation. Here we report a premature infant that underwent PD on day of life 9 for a FIP. The infant recovered well from this episode and was discharged home without known sequelae. Subsequently, the same patient presented 16 months later with peritonitis. A perforation was discovered at laparotomy without evidence of surrounding necrosis. Given this finding, we believe this second episode of perforation was at the same site as the initial episode of FIP. The finding of FIP has been described without findings of surrounding necrosis. However, we believe this to be the first report of delayed perforation greater than 1 year from initial presentation after FIP treated definitively with peritoneal drain.

  17. MODELING OF NONLINEAR CYCLIC LOAD BEHAVIOR OF I-SHAPED COMPOSITE STEEL-CONCRETE SHEAR WALLS OF NUCLEAR POWER PLANTS

    Directory of Open Access Journals (Sweden)

    AHMER ALI

    2013-02-01

    Full Text Available In recent years steel-concrete composite shear walls have been widely used in enormous high-rise buildings. Due to high strength and ductility, enhanced stiffness, stable cycle characteristics and large energy absorption, such walls can be adopted in the auxiliary building; surrounding the reactor containment structure of nuclear power plants to resist lateral forces induced by heavy winds and severe earthquakes. This paper demonstrates a set of nonlinear numerical studies on I-shaped composite steel-concrete shear walls of the nuclear power plants subjected to reverse cyclic loading. A three-dimensional finite element model is developed using ABAQUS by emphasizing on constitutive material modeling and element type to represent the real physical behavior of complex shear wall structures. The analysis escalates with parametric variation in steel thickness sandwiching the stipulated amount of concrete panels. Modeling details of structural components, contact conditions between steel and concrete, associated boundary conditions and constitutive relationships for the cyclic loading are explained. Later, the load versus displacement curves, peak load and ultimate strength values, hysteretic characteristics and deflection profiles are verified with experimental data. The convergence of the numerical outcomes has been discussed to conclude the remarks.

  18. Cyclic-Tension Fatigue Behavior in a SS400 Steel Plate Studied Using Ultrasonic Linear and Nonlinear Techniques

    Science.gov (United States)

    Yamagishi, Hideki; Fukuhara, Mikio

    2015-11-01

    Three acoustic probe configurations were used to assess cyclic-tension fatigue in SS400 steel at room temperature via a diffracted horizontally polarized shear wave (SH) transmission method. Linear analysis of the propagation time and amplitude of shear and longitudinal waves with fatigue progression revealed that the linear behavior was governed by residual stress, attributed to the acoustoelastic effect. Specifically, the propagation time of the shear waves increased and the wave amplitude decreased with fatigue progression. Our results also revealed that the propagation paths of the waves became deeper with progressive fatigue. Additionally, when the probe angle was optimized for diffraction, the estimated change in the length prior to fatigue breakage was 0.61 pct. Nonlinear analysis results revealed that second harmonic β-parameters increased as fatigue progressed, up to ~800 pct for the optimal frequency configuration; this was attributed to an increase in the number of dislocation-associated viscoelastic effects. The proposed approach shows great potential for nondestructive evaluation of metal fatigue via parameter analysis of residual stress and dislocation variations.

  19. Effect of reducing agents in tuning the third-order optical nonlinearity and optical limiting behavior of reduced graphene oxide

    Science.gov (United States)

    Muruganandi, G.; Saravanan, M.; Vinitha, G.; Jessie Raj, M. B.; Sabari Girisun, T. C.

    2017-05-01

    Reduced graphene oxide (rGO) was prepared by reduction method using various reductants like hydrazine, sodium borohydride and ascorbic acid. XRD and Raman analysis confirmed the effective removal of functional groups in GO. SEM revealed that rGO consists of thin crumpled and disordered sheets closely associated with each other. Blue shift in UV-absorption maxima was due to weak interlayer coupling between the layers of rGO. Third order NLO properties of dispersed rGO were measured by Z-scan technique (532 nm, 50 mW). Both GO and rGO possess self defocusing, saturable absorption and optical limiting behavior. The nonlinear component of refractive index, absorption coefficient and optical susceptibility were found to be 10-8 cm2/W, 10-3 cm/W and 10-6 esu respectively. Tunability of NLO coefficients with altering functional groups upon rGO was achieved. rGO prepared using hydrazine with high NLO coefficient and excellent durability, signify the scope of utilizing them as optical limiters.

  20. A time domain system identification for nonlinear behaviors of a seismic isolator using the secant stiffness model

    Energy Technology Data Exchange (ETDEWEB)

    Park, H. W.; Jeon, Y. S. [KAERI, Taejon (Korea, Republic of)

    2002-10-01

    Nonlinear hysteretic behaviors and stiffness changes of a seismic isolator are identified by using a Time Domain System Identification (TDSI) based on the secant stiffness model. A new regularity condition of tangent stiffness used in the current TDSI is proposed instead of that used in the conventional Duhem hysteretic operator. The proposed regularity condition is defined with respect to time while that of Duhem hysteretic operator is defined with respect to displacements and restoring forces. The secant stiffness model for the TDSI is obtained by approximating the tangent stiffness under the proposed regularity condition by the secant stiffness at each time step. A least square method is employed to minimize the difference between the calculated response and measured response for the time domain system identification of the secant stiffness. The regularity condition of the secant stiffness is utilized to alleviate ill-posedness of the TDSI and to yield physically meaningful solutions by means of the regularization technique. An optimal regularization factor determined by Geometric Mean Scheme (GMS) is adopted to yield appropriate regularization effects on the system identification. The validity of the proposed method is presented through two numerical examples.

  1. Stochastic analysis of laminated composite plates on elastic foundation: The cases of post-buckling behavior and nonlinear free vibration

    Energy Technology Data Exchange (ETDEWEB)

    Singh, B.N., E-mail: bnsingh@aero.iitkgp.ernet.i [Department of Aerospace Engineering, IIT Kharagpur 721 302, West Bengal (India); Lal, Achchhe [Department of Mechanical Engineering, SVNIT, Surat 395007 (India)

    2010-10-15

    This study deals with the stochastic post-buckling and nonlinear free vibration analysis of a laminated composite plate resting on a two parameters Pasternak foundation with Winkler cubic nonlinearity having uncertain system properties. The system properties are modeled as basic random variables. A C{sup 0} nonlinear finite element formulation of the random problem based on higher-order shear deformation theory in the von Karman sense is presented. A direct iterative method in conjunction with a stochastic nonlinear finite element method proposed earlier by the authors is extended to analyze the effect of uncertainty in system properties on the post-buckling and nonlinear free vibration of the composite plates having Winler type of geometric nonlinearity. Mean as well as standard deviation of the responses have been obtained for various combinations of geometric parameters, foundation parameters, stacking sequences and boundary conditions and compared with those available in the literature and Monte Carlo simulation.

  2. Acquired perforating dermatosis in a patient with chronic renal failure*

    Science.gov (United States)

    Fernandes, Karen de Almeida Pinto; Lima, Lourenço de Azevedo; Guedes, Juliana Chaves Ruiz; Lima, Ricardo Barbosa; D'Acri, Antônio Macedo; Martins, Carlos José

    2016-01-01

    Perforating dermatoses are a group of skin diseases characterized by transepidermal elimination of dermal material. The disease is divided into two groups: the primary group and the secondary group. The classical or primary perforating dermatoses are subdivided into four types according to the eliminated dermal materials: Kyrle disease, perforating reactive collagenosis, elastosis perforans serpiginosa, and perforating folliculitis. The secondary form is known as acquired perforating dermatosis. The term was proposed in 1989 by Rapini to designate the perforating dermatoses affecting adult patients with systemic disease, regardless of the dermal materials eliminated. This report describes a case of the disease with elimination of collagen and elastic fibers in a patient with chronic renal failure.

  3. Contact lens rehabilitation following repaired corneal perforations

    Directory of Open Access Journals (Sweden)

    Sreenivas V

    2006-03-01

    Full Text Available Abstract Background Visual outcome following repair of post-traumatic corneal perforation may not be optimal due to presence of irregular keratometric astigmatism. We performed a study to evaluate and compare rigid gas permeable contact lens and spectacles in visual rehabilitation following perforating corneal injuries. Method Eyes that had undergone repair for corneal perforating injuries with or without lens aspiration were fitted rigid gas permeable contact lenses. The fitting pattern and the improvement in visual acuity by contact lens over spectacle correction were noted. Results Forty eyes of 40 patients that had undergone surgical repair of posttraumatic corneal perforations were fitted rigid gas permeable contact lenses for visual rehabilitation. Twenty-four eyes (60% required aphakic contact lenses. The best corrected visual acuity (BCVA of ≥ 6/18 in the snellen's acuity chart was seen in 10 (25% eyes with spectacle correction and 37 (92.5% eyes with the use of contact lens (p Conclusion Rigid gas permeable contact lenses are better means of rehabilitation in eyes that have an irregular cornea due to scars caused by perforating corneal injuries.

  4. Liver Parenchyma Perforation following Endoscopic Retrograde Cholangiopancreatography

    Directory of Open Access Journals (Sweden)

    Hiroto Kayashima

    2011-08-01

    Full Text Available Although endoscopic retrograde cholangiopancreatography (ERCP is an effective modality for the diagnosis and treatment of biliary and pancreatic diseases, it is still related with several severe complications. We report on the case of a female patient who developed liver parenchyma perforation following ERCP. She underwent ERCP with sphincterotomy and extraction of a common bile duct stone. Shortly after ERCP, abdominal distension was identified. Abdominal computed tomography revealed intraabdominal air leakage and leakage of contrast dye penetrating the liver parenchyma into the space around the spleen. Since periampullary perforation related to sphincterotomy could not be denied, she was referred for immediate surgery. Obvious perforation could not be found at surgery. Cholecystectomy, insertion of a T tube into the common bile duct, placement of a duodenostomy tube and drainage of the retroperitoneum were performed. She did well postoperatively and was discharged home on postoperative day 28. In conclusion, as it is well recognized that perforation is one of the most serious complication related to ERCP, liver parenchyma perforation should be suspected as a cause.

  5. Liver Parenchyma Perforation following Endoscopic Retrograde Cholangiopancreatography

    Science.gov (United States)

    Kayashima, Hiroto; Ikegami, Toru; Kasagi, Yuta; Hidaka, Gen; Yamazaki, Koji; Sadanaga, Noriaki; Itoh, Hiroyuki; Emi, Yasunori; Matsuura, Hiroshi; Okadome, Kenichiro

    2011-01-01

    Although endoscopic retrograde cholangiopancreatography (ERCP) is an effective modality for the diagnosis and treatment of biliary and pancreatic diseases, it is still related with several severe complications. We report on the case of a female patient who developed liver parenchyma perforation following ERCP. She underwent ERCP with sphincterotomy and extraction of a common bile duct stone. Shortly after ERCP, abdominal distension was identified. Abdominal computed tomography revealed intraabdominal air leakage and leakage of contrast dye penetrating the liver parenchyma into the space around the spleen. Since periampullary perforation related to sphincterotomy could not be denied, she was referred for immediate surgery. Obvious perforation could not be found at surgery. Cholecystectomy, insertion of a T tube into the common bile duct, placement of a duodenostomy tube and drainage of the retroperitoneum were performed. She did well postoperatively and was discharged home on postoperative day 28. In conclusion, as it is well recognized that perforation is one of the most serious complication related to ERCP, liver parenchyma perforation should be suspected as a cause. PMID:21960953

  6. Surgical Treatment of Perforation Esophageal Carcinoma

    Institute of Scientific and Technical Information of China (English)

    Depu Duan; Jihua Zou; Zhigang Cai; Shengyong Wu; Haibo Xiao; Yiyong Zhou; Xiang Liang; Dekui Sun; Songchang Wu

    2006-01-01

    OBJECTIVE To determine the ideal method of surgical preoperative treatment for perforation with esophageal carcinoma.METHODS 36 cases of perforation with esophageal carcinoma were treated surgically in this series.Perforations occurred into the right lung in14 cases ,the mediastinum in 17 cases and trachea in 5 cases.Open thoracic surgery was performed in 34 cases,in which the right thoracic approach using a 3-incision method was applied in 16 cases,and operation by stages in 15 cases.Of the 34 cases,retrosternal substitution of the esophagus with stomach or colon was performed in 26 cases.RESULTS Surgery was successful in 31 cases and operative death occurred in 3 cases.The postoperative follow up study was from 3~72months.Of these cases 15 wree alive at 7~12 months, 2 at 24 months,and 1 at 72 months. The results can be considered satisfactory.CONCLUSION The therapeutic results of surgical treatment of perforation with esophageal carcinoma were markedly superior to that of conventional conservative treatment. The authors suggest that surgical intervention without delay should be undertaken for patients having a perforation with carcinoma of the esophagus. A right thoracic approach with a 3-incision method (retrosternal replacement of esophagus with stomach or colon) or operation by stages is preferable.

  7. Mnemonic discrimination relates to perforant path integrity: An ultra-high resolution diffusion tensor imaging study.

    Science.gov (United States)

    Bennett, Ilana J; Stark, Craig E L

    2016-03-01

    Pattern separation describes the orthogonalization of similar inputs into unique, non-overlapping representations. This computational process is thought to serve memory by reducing interference and to be mediated by the dentate gyrus of the hippocampus. Using ultra-high in-plane resolution diffusion tensor imaging (hrDTI) in older adults, we previously demonstrated that integrity of the perforant path, which provides input to the dentate gyrus from entorhinal cortex, was associated with mnemonic discrimination, a behavioral outcome designed to load on pattern separation. The current hrDTI study assessed the specificity of this perforant path integrity-mnemonic discrimination relationship relative to other cognitive constructs (identified using a factor analysis) and white matter tracts (hippocampal cingulum, fornix, corpus callosum) in 112 healthy adults (20-87 years). Results revealed age-related declines in integrity of the perforant path and other medial temporal lobe (MTL) tracts (hippocampal cingulum, fornix). Controlling for global effects of brain aging, perforant path integrity related only to the factor that captured mnemonic discrimination performance. Comparable integrity-mnemonic discrimination relationships were also observed for the hippocampal cingulum and fornix. Thus, whereas perforant path integrity specifically relates to mnemonic discrimination, mnemonic discrimination may be mediated by a broader MTL network.

  8. Oriented cluster perforating technology and its application in horizontal wells

    Directory of Open Access Journals (Sweden)

    Huabin Chen

    2016-11-01

    Full Text Available An oriented cluster perforating technology, which integrates both advantages of cluster and oriented perforating, will help solve a series of technical complexities in horizontal well drilling. For realizing its better application in oil and gas development, a series of technologies were developed including perforator self-weight eccentricity, matching of the electronic selective module codes with the surface program control, axial centralized contact signal transmission, and post-perforation intercluster sealing insulation. In this way, the following functions could be realized, such as cable-transmission horizontal well perforator self-weight orientation, dynamic signal transmission, reliable addressing & selective perforation and post-perforation intercluster sealing. The combined perforation and bridge plug or the multi-cluster perforation can be fulfilled in one trip of perforation string. As a result, the horizontal-well oriented cluster perforating technology based on cable conveying was developed. This technology was successfully applied in unconventional gas reservoir exploitation, such as shale gas and coalbed methane, with accurate orientation, reliable selective perforation and satisfactory inter-cluster sealing. The horizontal-well oriented cluster perforating technology benefits the orientation of horizontal well drilling with a definite target and direction, which provides a powerful support for the subsequent reservoir stimulation. It also promotes the fracturing fluid to sweep the principal pay zones to the maximum extent. Moreover, it is conductive to the formation of complex fracture networks in the reservoirs, making quality and efficient development of unconventional gas reservoirs possible.

  9. Traumatic oesophageal perforation due to haematoma

    DEFF Research Database (Denmark)

    Grønhøj Larsen, Christian; Brandt, Bodil

    2014-01-01

    INTRODUCTION: Traumatic oesophageal perforation is a rare, life-threatening emergency that requires early recognition and prompt surgical management. PRESENTATION OF CASE: We present an unusual case of a patient on warfarin treatment developed an intramural oesophageal haematoma following blunt......; or the intramural hematoma gradually lysed and causing late perforation. CONCLUSION: Although extremely rare, an oesophageal haematoma and late complications must be considered in patients on anti-coagulant therapy following blunt thoracic trauma and complaining only of chest pain....... thoracic trauma leading to perforation on the 18th day. DISCUSSION: In treatment of oesophageal haematoma in patients on vitamin-K antagonists, strict control of the International Normalized Ratio (INR) is essential along with total parenteral nutrition therapy and refrainment through nasogastric tubes...

  10. Traumatic Forefoot Reconstructions With Free Perforator Flaps.

    Science.gov (United States)

    Zhu, Yue-Liang; He, Xiao-Qing; Wang, Yi; Lv, Qian; Fan, Xin-Yv; Xu, Yong-Qing

    2015-01-01

    The forefoot is critical to normal walking; thus, any reconstruction of forefoot defects, including the soft tissues, must be carefully done. The free perforator flap, with its physiologic circulation, lower donor site morbidity, and minimal thickness is the most popular technique in plastic and microsurgery, and is theoretically the most suitable for such forefoot reconstruction. However, these flaps are generally recognized as more difficult and time-consuming to create than other flaps. In 41 patients with traumatic forefoot defects, we reconstructed the forefoot integument using 5 types of free perforator flaps. The overall functional and cosmetic outcomes were excellent. Three flaps required repeat exploration; one survived. The most common complications were insufficient perfusion and the need for second debulking. The key to our success was thoroughly debriding devitalized bone and soft tissue before attaching the flap. Forefoot reconstruction with a free perforator flap provides better function, better cosmesis, better weightbearing, and better gait than the other flaps we have used.

  11. Fast track pathway for perforated appendicitis.

    Science.gov (United States)

    Frazee, Richard; Abernathy, Stephen; Davis, Matthew; Isbell, Travis; Regner, Justin; Smith, Randall

    2017-04-01

    Perforated appendicitis is associated with an increased morbidity and length of stay. "Fast track" protocols have demonstrated success in shortening hospitalization without increasing morbidity for a variety of surgical processes. This study evaluates a fast track pathway for perforated appendicitis. In 2013, a treatment pathway for perforated appendicitis was adopted by the Acute Care Surgery Service for patients having surgical management of perforated appendicitis. Interval appendectomy was excluded. Patients were treated initially with intravenous antibiotics and transitioned to oral antibiotics and dismissed when medically stable and tolerating oral intake. A retrospective review of patients managed on the fast track pathway was undertaken to analyze length of stay, morbidity, and readmissions. Thirty-four males and twenty-one females with an average age of 46.8 years underwent laparoscopic appendectomy for perforated appendicitis between January 2013 and December 2014. Pre-existing comorbidities included hypertension 42%, diabetes mellitus 11%, COPD 5% and heart disease 2%. No patient had conversion to open appendectomy. Average length of stay was 2.67 days and ranged from 1 to 12 days (median 2 days). Postoperative morbidity was 20% and included abscess (6 patients), prolonged ileus (3 patients), pneumonia (1 patient), and congestive heart failure (1 patient). Five patients were readmitted for abscess (3 patients), congestive heart failure (1 patient), and pneumonia (1 patient). A fast track pathway for perforated appendicitis produced shorter length of stay and acceptable postoperative morbidity and readmission. This offers the potential for significant cost savings over current national practice patterns. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Right-Sided Sigmoid Diverticular Perforation

    Directory of Open Access Journals (Sweden)

    Andrew Little

    2012-04-01

    Full Text Available Diverticulosis is a common disorder among geriatric patients, of whom 10% to 25% go on to develop diverticulitis. Known complications of diverticulitis include formation of phlegmon, fistula, bowel obstruction, bleeding, perforation, and colonic abscess. A less common complication is perforation with formation of an extra-abdominal necrotizing abscess. This case is a report of an 83-year-old female who presented to the emergency department with a necrotizing abdominal wall abscess secondary to right-sided diverticular microperforation. [West J Emerg Med. 2012;13(1:103–105.

  13. Pneumoperitoneum Secondary to Spontaneously Perforated Pyometra

    Directory of Open Access Journals (Sweden)

    Benjamin A. Raymond

    2017-01-01

    Full Text Available Pyometra, by definition, is a collection of purulent fluid within the uterine cavity. Incidence has been estimated to range from 0.1% to 0.5%. Typically, this is linked to postmenopausal women; however, it has been linked to premenopausal women with concordant use of intrauterine devices. Based on our knowledge, there have been less than 50 recorded cases reported in the English literature regarding perforation of pyometra resulting in acute abdomen and fewer than 25 resulting in pneumoperitoneum. We report a patient who was evaluated for diffuse peritonitis caused by perforated pyometra who was successfully treated with surgical intervention.

  14. Duodenal Perforation Precipitated by Scrub Typhus.

    Science.gov (United States)

    Rajat, Raghunath; Deepu, David; Jonathan, Arul Jeevan; Prabhakar, Abhilash Kundavaram Paul

    2015-01-01

    Scrub typhus is an acute febrile illness usually presenting with fever, myalgia, headache, and a pathognomonic eschar. Severe infection may lead to multiple organ failure and death. Gastrointestinal tract involvement in the form of gastric mucosal erosions and ulcerations owing to vasculitis resulting in gastrointestinal bleeding is common. This process may worsen a pre-existent asymptomatic peptic ulcer, causing duodenal perforation, and present as an acute abdomen requiring surgical exploration. We report the case of a patient with no previous symptoms or risk factors for a duodenal ulcer, who presented with an acute duodenal perforation, probably precipitated by scrub typhus infection.

  15. Duodenal perforation precipitated by scrub typhus

    Directory of Open Access Journals (Sweden)

    Raghunath Rajat

    2015-01-01

    Full Text Available Scrub typhus is an acute febrile illness usually presenting with fever, myalgia, headache, and a pathognomonic eschar. Severe infection may lead to multiple organ failure and death. Gastrointestinal tract involvement in the form of gastric mucosal erosions and ulcerations owing to vasculitis resulting in gastrointestinal bleeding is common. This process may worsen a pre-existent asymptomatic peptic ulcer, causing duodenal perforation, and present as an acute abdomen requiring surgical exploration. We report the case of a patient with no previous symptoms or risk factors for a duodenal ulcer, who presented with an acute duodenal perforation, probably precipitated by scrub typhus infection.

  16. Pseudo-skin model for gravel-filled perforations

    Energy Technology Data Exchange (ETDEWEB)

    Onyekonwu, M.O. [Laser Engineering Consultants/Uniport, Port Harcourt (Nigeria); Okonkwo, F.C. [University of Port Harcourt Uniport, Port Harcourt (Nigeria)

    1997-11-05

    This paper discusses pressure losses due to flow in perforations filled with gravel or with formation material. These pressure losses are added to the pressure losses caused by convergence to perforations to obtain the pseudo-skin due to gravel-filled perforations. Calculation of the pressure loss due to convergence to perforation is discussed elsewhere. The flow in the perforation tunnel could be turbulent or laminar. Therefore, we calculated the pressure losses in a gravel-filled perforation using Forchheimer`s equation or Darcy`s law. However, we expect that the flow in such tunnels will be turbulent. Results from our model agree with experimental data published elsewhere. Also, our results show that pressure losses during flow through gravel-filled perforations could be substantial. Therefore, productivities of gravel pack completions may differ significantly from perforated completions in competent formation without gravel pack

  17. Preoperative staging of perforated diverticulitis by computed tomography scanning

    NARCIS (Netherlands)

    M.P.M. Gielens; I.M. Mulder (Irene); E. van der Harst (Erwin); M.P. Gosselink (Martijn Pieter); K.J. Kraal; H.T. Teng; J.F. Lange (Johan); J. Vermeulen (Jefrey)

    2012-01-01

    textabstractBackground: Treatment of perforated diverticulitis depends on disease severity classified according to Hinchey's preoperative classification. This study assessed the accuracy of preoperative staging of perforated diverticulitis by computerized tomography (CT) scanning. Methods: All patie

  18. Spin-glass phase transition and behavior of nonlinear susceptibility in the Sherrington-Kirkpatrick model with random fields

    Science.gov (United States)

    Morais, C. V.; Zimmer, F. M.; Lazo, M. J.; Magalhães, S. G.; Nobre, F. D.

    2016-06-01

    The behavior of the nonlinear susceptibility χ3 and its relation to the spin-glass transition temperature Tf in the presence of random fields are investigated. To accomplish this task, the Sherrington-Kirkpatrick model is studied through the replica formalism, within a one-step replica-symmetry-breaking procedure. In addition, the dependence of the Almeida-Thouless eigenvalue λAT (replicon) on the random fields is analyzed. Particularly, in the absence of random fields, the temperature Tf can be traced by a divergence in the spin-glass susceptibility χSG, which presents a term inversely proportional to the replicon λAT. As a result of a relation between χSG and χ3, the latter also presents a divergence at Tf, which comes as a direct consequence of λAT=0 at Tf. However, our results show that, in the presence of random fields, χ3 presents a rounded maximum at a temperature T* which does not coincide with the spin-glass transition temperature Tf (i.e., T*>Tf for a given applied random field). Thus, the maximum value of χ3 at T* reflects the effects of the random fields in the paramagnetic phase instead of the nontrivial ergodicity breaking associated with the spin-glass phase transition. It is also shown that χ3 still maintains a dependence on the replicon λAT, although in a more complicated way as compared with the case without random fields. These results are discussed in view of recent observations in the LiHoxY1 -xF4 compound.

  19. Perforated diverticulitis presenting as necrotising fasciitis of the leg

    Directory of Open Access Journals (Sweden)

    Talbot Robert

    2008-02-01

    Full Text Available Abstract Diverticulosis of the colon is a common condition of increasing age. Complications of diverticulitis including stricture, perforation and fistula formation often require surgery. Perforated diverticulitis may rarely present with spreading superficial sepsis. We describe for the first time, to our knowledge, a case of retroperitoneal diverticula perforation presenting as necrotising fasciitis of the leg necessitating hind-quarter amputation.

  20. Spontaneous perforation of a pyometra presenting as generalized peritonitis.

    Science.gov (United States)

    Hosking, S. W.

    1985-01-01

    Eleven cases of spontaneous perforation of a pyometra have previously been reported. All were associated with, and probably secondary to, cervical occlusion. A further case is described, but differs in that the cervical canal was patent. In the absence of other possible causes of uterine perforation, the aetiology of the perforation in this case remains uncertain. Images Figure 1 PMID:4040634

  1. Determination of the Fundamental Frequency of Perforated Rectangular Plates: Concentrated Negative Mass Approach for the Perforation

    Directory of Open Access Journals (Sweden)

    Kiran D. Mali

    2013-01-01

    Full Text Available This paper is concerned with a vibration analysis of perforated rectangular plates with rectangular perforation pattern of circular holes. The study is particularly useful in the understanding of the vibration of sound absorbing screens, head plates, end covers, or supports for tube bundles typically including tube sheets and support plates used in the mechanical devices. An energy method is developed to obtain analytical frequencies of the perforated plates with clamped edge, support conditions. Perforated plate is considered as plate with uniformly distributed mass. Holes are considered as concentrated negative masses. The analytical procedure using the Galerkin method is adopted. The deflected surface of the plate is approximated by the cosine series which satisfies the boundary conditions. Finite element method (FEM results have been used to illustrate the validity of the analytical model. The comparisons show that the analytical model predicts natural frequencies reasonably well for holes of small size.

  2. Intestinal perforation caused by multiple magnet ingestion

    Directory of Open Access Journals (Sweden)

    Nergul Corduk

    2014-01-01

    Full Text Available Multiple magnet ingestion is rare, but can cause serious gastrointestinal complications. We report a case of 7-year-old girl with multiple intestinal perforations caused by multiple magnet ingestion. The aim of this report is to draw attention to magnetic toys, results of magnet ingestion and the importance of timing of operation.

  3. [Small bowel perforation caused by magnetic toys].

    Science.gov (United States)

    Schroepfer, E; Siauw, C; Hoecht, B; Meyer, T

    2010-06-01

    Accidental ingestion of foreign bodies is a common problem in infants and childhood, but ingestion of magnetic construction toys is very rare. In the case of ingestion of multiple parts of these magnetic construction toys, they may attract each other through the intestinal walls, causing pressure necrosis, perforation, fistula formation or intestinal obstruction. A 20-month-old boy presented with a three-day history of abdominal pain and bilious vomiting. Physical examination revealed a slighted distended abdomen. The -white blood cell count was increased, but the C-reactive protein was normal. Ultrasound and X-ray of the abdomen showed a distended bowel loop in the right upper quadrant, a moderate amount of free intraperitoneal liquid and 4 foreign bodies. Emergency laparotomy was performed and 2 perforations in the ileum were detected. The perforations were caused by a magnetic construction toy and 2 iron globes. The fourth foreign body was a glass marble. The foreign bodies were removed, both perforations were primarily sutured. The child was discharged on postoperative day 10 after an uneventful recovery. Parents should be warned against the potential dangers of children's constructions toys that contain these kinds of magnets.

  4. Acute phlegmonous gastritis complicated by delayed perforation.

    Science.gov (United States)

    Min, Sun Young; Kim, Yong Ho; Park, Won Seo

    2014-03-28

    Here, we report on a case of acute phlegmonous gastritis (PG) complicated by delayed perforation. A 51-year-old woman presented with severe abdominal pain and septic shock symptoms. A computed tomography scan showed diffuse thickening of the gastric wall and distention with peritoneal fluid. Although we did not find definite evidence of free air on the computed tomography (CT) scan, the patient's clinical condition suggested diffuse peritonitis requiring surgical intervention. Exploratory laparotomy revealed a thickened gastric wall with suppurative intraperitoneal fluid in which Streptococcus pyogenes grew. There was no evidence of gastric or duodenal perforation. No further operation was performed at that time. The patient was conservatively treated with antibiotics and proton pump inhibitor, and her condition improved. However, she experienced abdominal and flank pain again on postoperative day 10. CT and esophagogastroduodenoscopy showed a large gastric ulcer with perforation. Unfortunately, although the CT showed further improvement in the thickening of the stomach and the mucosal defect, the patient's condition did not recover until a week later, and an esophagogastroduodenoscopy taken on postoperative day 30 showed suspected gastric submucosal dissection. We performed total gastrectomy as a second operation, and the patient recovered without major complications. A pathological examination revealed a multifocal ulceration and necrosis from the mucosa to the serosa with perforation.

  5. Infantile perforated appendicitis: A forgotten diagnosis

    Directory of Open Access Journals (Sweden)

    Katherine W. Gonzalez

    2015-04-01

    Full Text Available Acute appendicitis in the infant is a rare surgical diagnosis despite its frequency in older patients. The clinical presentation is often vague and can be misleading. We present the successful diagnosis and treatment of a 3 month old female with perforated appendicitis.

  6. Reactive Perforating Collagenosis In Borderline Lepromatous Leprosy

    Directory of Open Access Journals (Sweden)

    Mendiratta Vibhu

    2000-01-01

    Full Text Available A 55 year old male having borderline lepromatous leprosy receiving MB-MDT for one and half year developed several keratoic papules and plaques with central plug and scar formation, mainly on his extremities. Histopathology form the lesion was consistent with reactive perforating collagenosis. Trivial trauma from scratching might have resulted in this phenomenon.

  7. Perforated membrane-type acoustic metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Langfeldt, F., E-mail: Felix.Langfeldt@haw-hamburg.de [Department of Automotive and Aeronautical Engineering, Hamburg University of Applied Sciences, Berliner Tor 9, D-20099 Hamburg (Germany); Kemsies, H., E-mail: Hannes.Kemsies@haw-hamburg.de [Department of Automotive and Aeronautical Engineering, Hamburg University of Applied Sciences, Berliner Tor 9, D-20099 Hamburg (Germany); Gleine, W., E-mail: Wolfgang.Gleine@haw-hamburg.de [Department of Automotive and Aeronautical Engineering, Hamburg University of Applied Sciences, Berliner Tor 9, D-20099 Hamburg (Germany); Estorff, O. von, E-mail: estorff@tu-harburg.de [Institute of Modelling and Computation, Hamburg University of Technology, Denickestr. 17, D-21073 Hamburg (Germany)

    2017-04-25

    This letter introduces a modified design of membrane-type acoustic metamaterials (MAMs) with a ring mass and a perforation so that an airflow through the membrane is enabled. Simplified analytical investigations of the perforated MAM (PMAM) indicate that the perforation introduces a second anti-resonance, where the effective surface mass density of the PMAM is much higher than the static value. The theoretical results are validated using impedance tube measurements, indicating good agreement between the theoretical predictions and the measured data. The anti-resonances yield high low-frequency sound transmission loss values with peak values over 25 dB higher than the corresponding mass-law. - Highlights: • A new membrane-type acoustic metamaterial exhibiting negative density is presented. • The metamaterial design contains a ring mass with a perforation through the membrane. • The sound transmission loss exhibits narrow-band peaks much higher than the mass-law. • The emergence of the peaks is explained using a simple theoretical model. • Impedance tube measurements are used to validate the theoretical predictions.

  8. Long-term survival after perforated diverticulitis

    NARCIS (Netherlands)

    J. Vermeulen (Jan); M.P. Gosselink (Martijn Pieter); W.C.J. Hop (Wim); E. van der Harst (Erwin); B.E. Hansen (Bettina); G.H.H. Mannaerts (Guido); P-P. Coene (Peter Paul); W.F. Weidema (Wibo); J.F. Lange (Johan)

    2011-01-01

    textabstractAim: Short-term survival after emergency surgery for perforated diverticulitis is poor. Less is known about long-term survival. The aims of this study were to evaluate long-term survival after discharge from hospital and to identify factors associated with prognosis. Method: All patients

  9. Jejunal Diverticular Perforation due to Enterolith

    Directory of Open Access Journals (Sweden)

    Ronaldo Nonose

    2011-08-01

    Full Text Available Jejunal diverticulosis is a rare entity with variable clinical and anatomical presentations. Although there is no consensus on the management of asymptomatic jejunal diverticular disease, some complications are potentially life-threatening and require early surgical treatment. Small bowel perforation secondary to jejunal diverticulitis by enteroliths is rare. The aim of this study was to report a case of small intestinal perforation caused by a large jejunal enterolith. An 86-year-old woman was admitted with signs of diffuse peritonitis. After initial fluid recovery the patient underwent emergency laparotomy. The surgery showed that she had small bowel diverticular disease, mainly localized in the proximal jejunum. The peritonitis was due to intestinal perforation caused by an enterolith 12 cm in length, localized inside one of these diverticula. The intestinal segment containing the perforated diverticulum with the enterolith was removed and an end-to-end anastomosis was done to reconstruct the intestinal transit. The patient recovered well and was discharged from hospital on the 5th postoperative day. There were no signs of abdominal pain 1 year after the surgical procedure. Although jejunal diverticular disease with its complications, such as formation of enteroliths, is difficult to suspect in patients with peritonitis, it should be considered as a possible source of abdominal infection in the elderly patient when more common diagnoses have been excluded.

  10. Discriminating between simple and perforated appendicitis

    NARCIS (Netherlands)

    M. Bröker (Mirelle); E.M.M. van Lieshout (Esther); M. van der Elst (Maarten); L.P. Stassen (Laurents); T. Schepers (Tim)

    2012-01-01

    textabstractBackground: Several studies have been performed in order to diagnose an acute appendicitis using history taking and laboratory investigations. The aim of this study was to create a model for the identification of a perforated appendicitis. Methods: All consecutive patients who have under

  11. Advances in micro-perforated panel absorbers

    Institute of Scientific and Technical Information of China (English)

    LIU Ke; TIAN Jing; JIAO Fenglei; L(U) Yadong

    2006-01-01

    Theoretical and experimental investigations on the performance of micro-perforated-panel absorbers are reviewed in this paper. By reviewing recent research work, this paper reveals a relationship between the maximum absorption coefficient and the limit of the absorption frequency bandwidth. It has been demonstrated that the absorption frequency bandwidth can be extended up to 3 or 4 octaves as the diameters of the micro-holes decrease. This has become possible with the development of the technologies for manufacturing micro-perforated panels,such as laser drilling, powder metallurgy, welded meshing and electro-etching to form micrometer order holes. In this paper, absorption characteristics of such absorbers in random fields and in high sound intensity are discussed both theoretically and experimentally. A new absorbing structure based on micro-perforated-panel absorbers demonstrate experimentally high sound absorption capability. This review shows that the micro-perforated-panel absorber has potentials to be one of ideal absorbing materials in the 21st century.

  12. Traumatic and nontraumatic perforation of hollow viscera.

    Science.gov (United States)

    Espinoza, R; Rodríguez, A

    1997-12-01

    Hollow viscus injuries are usually managed with few complications. However, if their diagnosis is delayed, or if reparative suture closure should fail, the patient is placed at risk of multiple organ failure. This article presents diagnostic approaches, emphasizing imaging modalities, and therapeutic strategies for three clinical scenarios of hollow viscus perforation: 1) acute appendicitis, 2) gastroduodenal peptic ulcer disease, and 3) trauma.

  13. Spontaneous closure of traumatic tympanic membrane perforations

    DEFF Research Database (Denmark)

    Jellinge, Marlene Ersgaard; Kristensen, S.; Larsen, K

    2015-01-01

    BACKGROUND: The treatment of traumatic tympanic membrane perforations varies in different investigations, ranging from observation to early surgical repair. The present study aimed to focus on the closure rate and the closure time in a group of patients treated with a watchful waiting policy. MET...

  14. Perforated stomach following the Heimlich maneuver.

    Science.gov (United States)

    Cowan, M; Bardole, J; Dlesk, A

    1987-03-01

    The use of infradiaphragmatic abdominal pressure for relief of airway obstruction caused by food was first described by Henry Heimlich in 1974. Since that time, several complications have been reported. We report a case of gastric perforation occurring in a choking victim following the application of the Heimlich maneuver.

  15. [Nineteenth century physicians against drum perforation].

    Science.gov (United States)

    Kierzek, A

    1995-01-01

    The trials of "organic" closure of drum perforation are described. The achievements of Adam Politzer, Hermann Schwartze, Joseph Gruber are presented. The first who used term "myringoplasty" was Emil Berthold. The "epochal" method of Wasilij Okuniew and achievements of Beniamin Gomperz are also depicted. The scientific activities of Polish otologists: Ludwik Guranowski and Rafai Spira were presented.

  16. Discriminating between simple and perforated appendicitis

    NARCIS (Netherlands)

    M. Bröker (Mirelle); E.M.M. van Lieshout (Esther); M. van der Elst (Maarten); L.P. Stassen (Laurents); T. Schepers (Tim)

    2012-01-01

    textabstractBackground: Several studies have been performed in order to diagnose an acute appendicitis using history taking and laboratory investigations. The aim of this study was to create a model for the identification of a perforated appendicitis. Methods: All consecutive patients who have

  17. A plausible explanation for male dominance in typhoid ileal perforation

    Directory of Open Access Journals (Sweden)

    Khan M

    2012-11-01

    Full Text Available Mohammad KhanDepartment of Microbiology, College of Medicine, Chichiri, Blantyre, MalawiAbstract: The phenomenon of consistent male dominance in typhoid ileal perforation (TIP is not well understood. It cannot be explained on the basis of microbial virulence, Peyer's patch anatomy, ileal wall thickness, gastric acidity, host genetic factors, or sex-linked bias in hospital attendance. The cytokine response to an intestinal infection in males is predominantly proinflammatory as compared with that in females, presumably due to differences in the sex hormonal milieu. Sex hormone receptors have been detected on lymphocytes and macrophages, including on Peyer's patches, inflammation of which (probably similar to the Shwartzman reaction/Koch phenomenon is the forerunner of TIP, and is not excluded from the regulatory effects of sex hormones. Hormonal control of host-pathogen interaction may override genetic control. Environmental exposure to Salmonella typhi may be more frequent in males, presumably due to sex-linked differences in hygiene practices and dining-out behavior. A plausible explanation of male dominance in TIP could include sex-linked differences in the degree of natural exposure of Peyer's patches to S. typhi. An alternative explanation may include sexual dimorphism in host inflammatory response patterns in Peyer's patches that have been induced by S. typhi. Both hypotheses are testable.Keywords: explanation, dominance, male, perforation, ileum, typhoid

  18. Semi-Analytical Solution for Stresses and Displacements in a Tunnel Excavated in Transversely Isotropic Formation with Non-Linear Behavior

    Science.gov (United States)

    Vu, The Manh; Sulem, Jean; Subrin, Didier; Monin, Nathalie

    2013-03-01

    A semi-analytical solution based on the transfer matrix technique is proposed to analyze the stresses and displacements in a two-dimensional circular opening excavated in transversely isotropic formation with non-linear behavior. A non-isotropic far field can be accounted for and the process of excavation is simulated by progressive reduction of the internal radial stress. A hyperbolic stress-strain law is proposed to take into account the non-linear behavior of the rock. The model contains seven independent parameters corresponding to the five elastic constants of an elastic material with transverse isotropy and to the friction coefficient and cohesion along the parallel joints (weakness planes). This approach is based on the discretization of the space into concentric rings. It requires the establishment of elementary solutions corresponding to the stress and displacement fields inside each ring for given conditions at its boundaries. These solutions, based on complex variable theory, are obtained in the form of infinite series. The appropriate number of terms to be kept for acceptable approximation is discussed. This non-linear model is applied to back analyze the convergence measurements of Saint-Martin-la-Porte access gallery. Short-term and long-term ground parameters are evaluated.

  19. Use of Perforator-Based Fasciocutaneous Flaps for Pressure Sore Reconstruction: Single-Perforator-Based Versus Multiple-Perforator-Based Flaps.

    Science.gov (United States)

    Chih-Hsun, Lin; Ma, Hsu

    2016-08-01

    A perforator-based fasciocutaneous flap is an alternative type of flap for pressure sore reconstruction. The aim of the present study was to determine whether a single-perforator-based flap or a multiple-perforator-based flap is better for pressure sore reconstruction. We reviewed the general data and postoperative complications in patients who received single-perforator-based or multiple-perforator-based fasciocutaneous flaps for pressure sore reconstruction between July 2009 and July 2012. No differences in general data, comorbidities, wound locations, flap sizes (73.9 vs. 67.0 cm(2), P = 0.455), and operative times were noted between the single-perforator-based and multiple-perforator-based flap groups. The flap rotation arc was larger in the single-perforator-based flap group than in the multiple-perforator-based flap group; however, the difference in the rotation arc was not significant (99.2° vs. 55.5°, respectively; P = 0.199). Two patients had total flap necrosis and one had partial flap necrosis in the single-perforator-based flap group. None of flap necrosis was noted in the multiple-perforator-based flap group; however, no significant differences in major complications were noted between the two groups. All donor sites underwent primary closure. This is the first clinical patient-matched research that considered the number of perforators and the rotation arc in applying perforator-based fasciocutaneous flaps in wound reconstruction. The results showed that the number of perforators is not the determinant factor of surgical outcome of the use of perforator-based fasciocutaneous flaps in pressure sore reconstruction. Thus, whether a single- or a multiple-perforator-based fasciocutaneous flap is used for flap perfusion does not jeopardize the operation. These results emphasize the reliability and convenience of using freestyle design of perforator-based flaps for pressure sore reconstruction. The design and clinical utility of the flaps have the

  20. Premixed Combustion of Kapok (ceiba pentandra seed oil on Perforated Burner

    Directory of Open Access Journals (Sweden)

    I.K.G. Wirawan

    2014-05-01

    Full Text Available Availability of fossil fuels in the world decrease gradually due to excessive fuel exploitation. This situations push researcher to look for alternative fuels as a source of renewable energy, one of them is kapok (ceiba pentandra seed oil. The aim this study was to know the behavior of laminar burning velocity, secondary Bunsen flame with open tip, cellular and triple flame. Premixed combustion of kapok seed oil was studied experimentally on perforated burner with equivalence ratio (φ varied from 0.30 until 1.07. The results showed that combustion of glycerol requires a large amount of air so that laminar burning velocity (SL is the highest at very lean mixture (φ =0.36 in the form of individual Bunsen flame on each of the perforated plate hole.  Perforated and secondary Bunsen flame both reached maximum SL similar with that of ethanol and higher than that of hexadecane. Slight increase of φ decreases drastically SL of perforated and secondary Bunsen flame. When the mixture was enriched, secondary Bunsen and perforated flame disappears, and then the flame becomes Bunsen flame with open tip and triple flame (φ = 0.62 to 1.07. Flame was getting stable until the mixture above the stoichiometry. Being isolated from ambient air, the SL of perforated flame, as well as secondary Bunsen flame, becomes equal with non-isolated flame. This shows the decreasing trend of laminar burning velocity while φ is increasing. When the mixture was enriched island (φ = 0.44 to 0.48 and petal (φ = 0.53 to 0.62 cellular flame take place. Flame becomes more unstable when the mixture was changed toward stoichiometry.

  1. Dynamical Behavior of Nonlinear Viscoelastic Timoshenko Beams with Damage on a Viscoelastic Foundation%粘弹性地基上损伤粘弹性Timoshenko梁的非线性动力学行为

    Institute of Scientific and Technical Information of China (English)

    盛冬发; 张燕; 程昌钧

    2004-01-01

    Based on convolution-type constitutive equations for linear viscoelastic materials with damage and the hypotheses of Timoshenko beams with large deflections, the nonlinear equations governing dynamical behavior of Timoshenko beams with damage on viscoelastic foundation were firstly derived. By using the Galerkin method in spatial domain, the nonlinear integro-partial differential equations were transformed into a set of integro-ordinary differential equations. The numerical methods in nonlinear dynamical systems, such as the phase-trajectory diagram, Poincare section and bifurcation figure, were used to solve the simplified systems of equations. It could be seen that simplified dynamical systems possess the plenty of nonlinear dynamical properties. The influence of load and material parameters on the dynamic behavior of nonlinear system were investigated in detail.

  2. On the determination of missing boundary data for solids with nonlinear material behaviors, using displacement fields measured on a part of their boundaries

    Science.gov (United States)

    Andrieux, Stéphane; Baranger, Thouraya N.

    2016-12-01

    The paper is devoted to the derivation of a numerical method for expanding available mechanical fields (stress vector and displacements) on a part of the boundary of a solid into its interior and up to unreachable parts of its boundary (with possibly internal surfaces). This expansion enables various identification or inverse problems to be solved in mechanics. The method is based on the solution of a nonlinear elliptic Cauchy problem because the mechanical behavior of the solid is considered as nonlinear (hyperelastic or elastoplastic medium). Advantage is taken of the assumption of convexity of the potentials used for modeling the constitutive equation, encompassing previous work by the authors for linear elastic solids, in order to derive an appropriate error functional. Two illustrations are given in order to evaluate the overall efficiency of the proposed method within the framework of small strains and isothermal transformation.

  3. Population pharmacokinetic analysis of nonlinear behavior of piperacillin during intermittent or continuous infusion in patients with cystic fibrosis.

    Science.gov (United States)

    Vinks, Alexander A; Den Hollander, Jan G; Overbeek, Shelley E; Jelliffe, Roger W; Mouton, Johan W

    2003-02-01

    The purpose of this study was to describe the nonlinear pharmacokinetics of piperacillin observed during intermittent infusion and continuous infusion by using a nonparametric population modeling approach. Data were 120 serum piperacillin concentration measurements from eight adult cystic fibrosis (CF) patients. Individual pharmacokinetic parameter estimates during intermittent infusion or continuous infusion were calculated by noncompartmental analysis and with a maximum iterative two-stage Bayesian estimator. To simultaneously describe concentration-time data during intermittent infusion and continuous infusion, nonlinear models were parameterized as two-compartment Michaelis-Menten models. Models were fit to the data with the nonparametric expectation maximization algorithm. The calculations were executed on a remote supercomputer. Nonlinear models were evaluated by log-likelihood estimates, residual plots, and R(2) values, and predictive performance was based on bias (mean weighted error [MWE]) and precision (mean weighted square error [MWSE]). A linear pharmacokinetic model could not describe combined intermittent infusion and continuous infusion data well. A good population model fit to the intermittent infusion and continuous infusion data was obtained with the constructed nonlinear models. Maximum a posteriori probability (MAP) Bayesian R(2) values for the nonlinear models were 0.96 to 0.97. Median parameter estimates for the best nonlinear model were as follows: K(m), 58 +/- 75 mg/liter (mean and standard deviation); V(max), 1,904 +/- 1,009 mg/h; volume of distribution of the central compartment, 14.1 +/- 3.0 liters; k(12), 0.63 +/- 0.41 h(-1); and k(21), 0.37 +/- 0.19 h(-1). The median bias (MWE) and precision (MWSE) values for MAP Bayesian estimation with the Michaelis-Menten model were 0.05 and 4.6 mg/liters, respectively. The developed nonlinear pharmacokinetic models can be used to optimize piperacillin therapy administered via continuous infusion in

  4. The "Gent" consensus on perforator flap terminology: preliminary definitions.

    Science.gov (United States)

    Blondeel, Phillip N; Van Landuyt, Koen H I; Monstrey, Stan J M; Hamdi, Moustapha; Matton, Guido E; Allen, Robert J; Dupin, Charles; Feller, Axel-Mario; Koshima, Isao; Kostakoglu, Naci; Wei, Fu-Chan

    2003-10-01

    Due to its increasing popularity, more and more articles on the use of perforator flaps have been reported in the literature during the past few years. Because the area of perforator flaps is new and rapidly evolving, there are no definitions and standard rules on terminology and nomenclature, which creates confusion when surgeons try to communicate and compare surgical techniques. This article attempts to represent the opinion of a group of pioneers in the field of perforator flap surgery. This consensus was reached after a terminology consensus meeting held during the Fifth International Course on Perforator Flaps in Gent, Belgium, on September 29, 2001. It stipulates not only the definitions of perforator vessels and perforator flaps but also the correct nomenclature for different perforator flaps. The authors believe that this consensus is a foundation that will stimulate further discussion and encourage further refinements in the future.

  5. The one-stage rhinoplasty septal perforation repair.

    Science.gov (United States)

    Foda, H M

    1999-08-01

    A combined septal perforation repair and rhinoplasty was performed in 20 patients (12 males, eight females; age range 16-36, mean age 29.6) presenting with septal perforations (size 1-4 cm) and external nasal deformities. The external rhinoplasty approach was used for all cases and the perforation was repaired using bilateral intranasal mucosal advancement flaps with a connective tissue interposition graft in between. The perforation was totally closed in 18 cases (90 per cent) with complete resolution of the pre-operative symptoms occurring in 16 (80 per cent). Cosmetically, 19 cases (95 per cent) were very satisfied with their aesthetic result. The exposure provided by the external approach proved to be very helpful in the process of septal perforation repair. Our results show that septal perforation repair could safely be combined with rhinoplasty and that some of the rhinoplasty manoeuvres used could even facilitate the process of septal perforation repair.

  6. Multiple, Pan-Enteric Perforation Secondary to Intestinal Tuberculosis

    Directory of Open Access Journals (Sweden)

    Irfan Masood

    2015-01-01

    Full Text Available Free perforation is one of the most feared complications of the intestinal tuberculosis. The terminal ileum is the most common site of perforation, while the majority of (90% perforations are solitary. Herein, we describe a case of a 25-year-old male who presented with generalized peritonitis requiring an emergency exploratory laparotomy, which revealed pan-enteric perforation characterized by multiple perforations of the small bowel extending 10–15 cm from the DJ flexure up to the terminal ileum. The perforations were primarily closed, while 6–8 cm of the diseased terminal ileum was resected and the two ends were brought out as double-barreled ostomy. To the best of our knowledge, such an extensive tuberculous perforation of the small bowel has not been previously reported in the literature before.

  7. Multiple, Pan-Enteric Perforation Secondary to Intestinal Tuberculosis

    Science.gov (United States)

    Masood, Irfan; Majid, Zain; Rafiq, Ali; Rind, Waqas; Zia, Aisha; Raza, Sajjad

    2015-01-01

    Free perforation is one of the most feared complications of the intestinal tuberculosis. The terminal ileum is the most common site of perforation, while the majority of (90%) perforations are solitary. Herein, we describe a case of a 25-year-old male who presented with generalized peritonitis requiring an emergency exploratory laparotomy, which revealed pan-enteric perforation characterized by multiple perforations of the small bowel extending 10–15 cm from the DJ flexure up to the terminal ileum. The perforations were primarily closed, while 6–8 cm of the diseased terminal ileum was resected and the two ends were brought out as double-barreled ostomy. To the best of our knowledge, such an extensive tuberculous perforation of the small bowel has not been previously reported in the literature before. PMID:26798540

  8. Traumatic tympanic membrane perforation: An overview

    Directory of Open Access Journals (Sweden)

    Asef Wani

    2016-01-01

    Full Text Available Objectives: The purpose of this study was to determine the various etiologies of traumatic tympanic membrane (TM perforations; their clinical presentation, observation and establish masterly inactivity as the main modality of management. Materials and Methods: A prospective study was performed on 350 cases of traumatic TM perforation in the Department of ENT, SKIMS Medical College, Srinagar from January 2010 to December 2014. Results: A total of 350 patients with the traumatic TM. Perforation was enrolled for this study. The group consisted of 231 male and 119 female patients. It affects all age groups with the highest incidence among middle age group. The right ear was involved in 94 (26.85% patients, the left ear in 249 (71.14% patients and bilateral ear involvement was seen in 7 (2% patients. The type of trauma included compression injury in 243 (64.42% patients, instrumental injury in 88 (25.14% patients, and blast injury in 19 (5.42% patients. Tinnitus was the most common complaint, followed by aural fullness, impaired hearing, otalgia, bleeding from ear and vertigo. 217 (62% patients presented with conductive hearing loss in the range of 20–35 dB, 77 (22% patients with 35 dB hearing loss, and 28 (8% patients presented with no air-bone gap. Grade I perforation (50% TM involvement was present in 38 (10.90% patients. Complete healing was observed within 2–6 weeks in 172 (49.10% patients and within 7–9 weeks in 112 (32.20% patients. 35 (10% patients showed complete healing within 10–12 weeks. The minimum time taken to heal was 21 days and maximum time 72 days. Complete healing was observed in 319 (91.10% patients. The intervention was only performed when spontaneous healing failed to occur after observing the patients for 1 week and included tympanoplasty in 8 (2.30% patients, trichloroacetic acid cauterization in 14 (4% patients. Residual perforation was observed in 9 (2.5% patients. Conclusion: In our experience, traumatic TM

  9. Focused ultrasonic beam behavior at a stress-free boundary and applicability for measuring nonlinear parameter in a reflection mode

    Science.gov (United States)

    Jeong, Hyunjo; Zhang, Shuzeng; Li, Xiongbing

    2017-02-01

    In this work, we employ a focused beam theory to modify the phase reversal at the stress-free boundary, and consequently enhance the second harmonic generation during its back-propagation toward the initial source position. We first confirmed this concept through experiment by using a spherically focused beam at the water-air interface, and measuring the reflected second harmonic and comparing with a planar wave reflected from the same stress-free or a rigid boundary. In order to test the feasibility of this idea for measuring the nonlinearity parameter of solids in a reflection mode, a focused nonlinear ultrasonic beam is modeled for focusing at and reflection from a stress-free boundary. A nonlinearity parameter expression is then defined together with diffraction and attenuation corrections.

  10. Introduction to nonlinear science

    CERN Document Server

    Nicolis, G

    1995-01-01

    One of the most unexpected results in science in recent years is that quite ordinary systems obeying simple laws can give rise to complex, nonlinear or chaotic, behavior. In this book, the author presents a unified treatment of the concepts and tools needed to analyze nonlinear phenomena and to outline some representative applications drawn from the physical, engineering, and biological sciences. Some of the interesting topics covered include: dynamical systems with a finite number of degrees of freedom, linear stability analysis of fixed points, nonlinear behavior of fixed points, bifurcation analysis, spatially distributed systems, broken symmetries, pattern formation, and chaotic dynamics. The author makes a special effort to provide a logical connection between ordinary dynamical systems and spatially extended systems, and to balance the emphasis on chaotic behavior and more classical nonlinear behavior. He also develops a statistical approach to complex systems and compares it to traditional deterministi...

  11. Nonlinear Physics of Plasmas

    CERN Document Server

    Kono, Mitsuo

    2010-01-01

    A nonlinearity is one of the most important notions in modern physics. A plasma is rich in nonlinearities and provides a variety of behaviors inherent to instabilities, coherent wave structures and turbulence. The book covers the basic concepts and mathematical methods, necessary to comprehend nonlinear problems widely encountered in contemporary plasmas, but also in other fields of physics and current research on self-organized structures and magnetized plasma turbulence. The analyses make use of strongly nonlinear models solved by analytical techniques backed by extensive simulations and available experiments. The text is written for senior undergraduates, graduate students, lecturers and researchers in laboratory, space and fusion plasmas.

  12. Rapunzel syndrome resulting in gastric perforation.

    Science.gov (United States)

    Parakh, J S; McAvoy, A; Corless, D J

    2016-01-01

    We report the case of an 18-year-old female patient with no past medical history who presented to the emergency department with acute abdominal pain and vomiting on the background of a long history of ingesting hair (trichophagia). Computed tomography revealed pneumoperitoneum and free fluid in keeping with visceral perforation. In addition, a large hair bolus was seen extending in contiguity from the stomach to the jejunum. A laparotomy was performed, revealing an anterior gastric perforation secondary to a 120cm long trichobezoar, which had formed a cast of the entire stomach, duodenum and proximal jejunum. The bezoar was removed and an omental patch repair to the anterior ulcer was performed. The patient made an excellent postoperative recovery and was discharged home with psychiatric follow-up review.

  13. Diffuse epithelial ingrowth after perforating keratoplasty.

    Science.gov (United States)

    Severin, M; Kirchhof, B; Hartmann, C

    1987-01-01

    Diffuse epithelial ingrowth was observed in 2 patients after perforating keratoplasty. Both cases involved a corneal graft after perforating injury with aphakia. In the first patient, the epithelial invasion was probably stimulated by a spatula synecholysis. In this case, the diagnosis was only made by histological investigation after enucleation. In the second patient the epithelial ingrowth was observed 8 months after keratoplasty. The clinical diagnosis was made on the basis of the typical slitlamp findings. In this case, the epithelial invasion led to hypotension with high resistance of outflow measured by electrotonography. In a very close chronological relation to the probable fall of chamber fluid secretion, development of a band-shaped keratopathy was observed.

  14. Detonator assembly for oil well perforating gun

    Energy Technology Data Exchange (ETDEWEB)

    Regalbuto, J.A.

    1981-02-18

    A safe/arm detonator assembly for use with an oil well perforating gun assembly has 2 housing members isolated from well-bore fluid which are rotatable from a safe position wherein a detonator and a booster are held out of alignment, to an armed position wherein the detonator and booster are moved into alignment. The detonator assembly is further arranged to be installed in a well perforating gun assembly such that the gun assembly may be transported with the detonator assembly in the safe position, and rotated to the armed position at the well site without disassembling the gun assembly. A safety pin may protrude from one of the housing members across a cavity between the members to cover and protect the booster from accidental detonation when the detonator assembly is in the safe position. The detonator and booster cavities may be held aligned by a detent ball. 16 claims.

  15. Thyroid Storm Precipitated by Duodenal Ulcer Perforation

    Directory of Open Access Journals (Sweden)

    Shoko Natsuda

    2015-01-01

    Full Text Available Thyroid storm is a rare and life-threatening complication of thyrotoxicosis that requires prompt treatment. Thyroid storm is also known to be associated with precipitating events. The simultaneous treatment of thyroid storm and its precipitant, when they are recognized, in a patient is recommended; otherwise such disorders, including thyroid storm, can exacerbate each other. Here we report the case of a thyroid storm patient (a 55-year-old Japanese male complicated with a perforated duodenal ulcer. The patient was successfully treated with intensive treatment for thyroid storm and a prompt operation. Although it is believed that peptic ulcer rarely coexists with hyperthyroidism, among patients with thyroid storm, perforation of a peptic ulcer has been reported as one of the causes of fatal outcome. We determined that surgical intervention was required in this patient, reported despite ongoing severe thyrotoxicosis, and reported herein a successful outcome.

  16. Endothelial reaction to perforating and non-perforating excimer laser excisions in rabbits

    Energy Technology Data Exchange (ETDEWEB)

    Koch, J.W.; Lang, G.K.; Naumann, G.O. (Department of Ophthalmology, University Erlangen-Nuernberg (Germany))

    1991-05-01

    With an ArF excimer laser (193 nm, 750 mJ/cm2, 20 Hz) and a special slit-mask system, perforating and non-perforating linear keratectomies were performed in 55 rabbit corneas with a follow-up from 1 hour to 6 months. Varying the pulse number according to ablation rate (0.8 micron/pulse) and corneal thickness, four linear radial excisions (3 mm length, 70 microns width) of increasing depth (70%, 80%, 90%, 100% perforation) were produced. The corneas were processed for light microscopy, scanning and transmission electron microscopy, and vital staining of the endothelium. Except for mild cell contact alterations and discrete single cell damage in the 90% deep excisions, no endothelial damage could be detected after non-perforating keratectomies. Minute (less than 20 microns) and small (20 to 100 microns maximal diameter) perforations induced cell enlargement, formation of pseudopodia, rosette-like figures, multi-nucleated giant cells, and ultimately uniform reformation of the cell pattern (1 hour to 7 days postoperatively). Larger excimer laser defects of Descemet's membrane (greater than 100 microns) were overgrown by dedifferentiated endothelial cells producing a new PAS-positive basement membrane. Vital staining revealed the complete and stable reorganization of the endothelium over these lesions within 6 months. The authors observations are similar to those reported on the endothelial repair process following other surgical manipulations (knife incisions, direct Nd:YAG-laser trauma) and support the applicability of excimer lasers for corneal trephination in patients.

  17. Gastric schwannoma coexists with peptic ulcer perforation

    Directory of Open Access Journals (Sweden)

    Volkan İnce

    2011-09-01

    Full Text Available Gastric schwannoma is a benign neoplasm that originates from sheet of nerve cell in stomach. Differential diagnosis of gastrointestinal stromal tumors, (GISTs which have malign potential, than these tumors, which definite diagnosis is determined by histopathological and immunohistochemical methods have clinical significance due to gastric schwannomas have excellent progress after surgical resection. We presented a case of gastric schwannoma coexists with peptic ulcer perforation with guide of literature in this study.

  18. High Temperature Perforating System for Geothermal Applications

    Energy Technology Data Exchange (ETDEWEB)

    Smart, Moises E. [Schlumberger Technology Corporation, Sugar Land, TX (United States)

    2017-02-28

    The objective of this project is to develop a perforating system consisting of all the explosive components and hardware, capable of reliable performance in high temperatures geothermal wells (>200 ºC). In this light we will focused on engineering development of these components, characterization of the explosive raw powder and developing the internal infrastructure to increase the production of the explosive from laboratory scale to industrial scale.

  19. Surgical complications of typhoid fever: enteric perforation.

    Science.gov (United States)

    Santillana, M

    1991-01-01

    Typhoid fever remains a prevalent disease in developing nations as the result of adverse socioeconomic factors. The most frequent complication, and principal cause of mortality, is perforation of the terminal ileum. This report presents our experience with 96 patients surgically treated at Cayetano Heredia University Hospital in Lima, Peru from 1972 to 1986. The clinical characteristics and the diverse surgical procedures utilized in the management of these patients are reviewed.

  20. Vitrectomy in double-perforation gunshot injury

    Directory of Open Access Journals (Sweden)

    Abd El Alim Mohamed A

    2013-11-01

    Full Text Available Ahmed Abd El Alim MohamedOphthalmology department, Ain Shams University, Cairo, EgyptObjective: This study sought to evaluate the result of pars plana vitrectomy in patients with gunshot wounds involving double perforation.Methods: This was a retrospective, noncomparative, interventional case series.Results: Eighteen patients (18 eyes with double-perforation gunshot injuries were treated from February 2010 to March 2012. The group included 16 men (88% and two women (11%; the mean age was 24 (15–33 years. In each case, vitrectomy was scheduled 1–6 weeks after repair of the entrance site. Associated retinal detachments were observed in two eyes (11%, retinal incarceration was observed surrounding the exit site in three eyes (16%, and retention of an intraocular foreign body was observed in two cases. After a follow-up period of 8 ± 2 months, two eyes (11% had achieved visual acuity (VA of 0.5, nine eyes (50% had achieved VA between 0.5 and 0.1, and seven eyes (38% had achieved VA between 0.1 and hand movement. The main reasons for functional failure (VA 0.1 to hand movement were macular dragging (due to fibrosis at the exit site near the macula in seven cases (38%, submacular hemorrhage in four cases (22%, and epimacular fibrosis in five cases (27%. All cases developed postoperative exotropia. One case (5% developed postoperative hemorrhage. No cases exhibited signs of postoperative redetachment.Conclusion: The outcome of pars plana vitrectomy in cases with double perforations is variable. Factors including the surgeon's skill level, the time to surgery, and the efficacy of the intraocular tamponade affect the postoperative outcome.Keywords: pars plana vitrectomy, gunshot injury, double perforation

  1. Duodenal Perforation Precipitated by Scrub Typhus

    OpenAIRE

    Raghunath Rajat; David Deepu; Arul Jeevan Jonathan; Abhilash Kundavaram Paul Prabhakar

    2015-01-01

    Scrub typhus is an acute febrile illness usually presenting with fever, myalgia, headache, and a pathognomonic eschar. Severe infection may lead to multiple organ failure and death. Gastrointestinal tract involvement in the form of gastric mucosal erosions and ulcerations owing to vasculitis resulting in gastrointestinal bleeding is common. This process may worsen a pre-existent asymptomatic peptic ulcer, causing duodenal perforation, and present as an acute abdomen requiring surgical explora...

  2. Septum nasal perforation: treatments and literature' review

    OpenAIRE

    Martinez Neto, Eulógio Emílio; Dolci, Luiz Eduardo Lutaif; Murta, Alexandre Antonio; Zanini, Fábio Duro

    2010-01-01

    Introduction: The present study consists in a bibliographical' review concerning the articles related to the different manifestations and forms of the septum nasal perforation, with a main emphasis in the description of its techniques of surgical correction. As the etiology, that is fundamentally iatrogenic, accordingly surgical trauma. Other causes include exhibition to chemical industrial reagents, cocaine use, intranasal steroidal therapeutic, neoplasia and, infectious conditions. There is...

  3. Liquid nitrogen ingestion followed by gastric perforation.

    Science.gov (United States)

    Berrizbeitia, Luis D; Calello, Diane P; Dhir, Nisha; O'Reilly, Colin; Marcus, Steven

    2010-01-01

    Ingestion of liquid nitrogen is rare but carries catastrophic complications related to barotrauma to the gastrointestinal tract. We describe a case of ingestion of liquid nitrogen followed by gastric perforation and respiratory insufficiency and discuss the mechanism of injury and management of this condition. Liquid nitrogen is widely available and is frequently used in classroom settings, in gastronomy, and for recreational purposes. Given the potentially lethal complications of ingestion, regulation of its use, acquisition, and storage may be appropriate.

  4. Intrathoracic Gastric Perforation in a Child

    Directory of Open Access Journals (Sweden)

    Mithat Günaydın

    2012-04-01

    Full Text Available Introduction: Paraesophageal hernia (PEH is a rare condition in children. The symptomatology of these patients is usually non-specific in the form of repeated attacks of respiratory infection and/or recurrent attacks of vomiting but can also lead to serious complications such as intrathoracic gastric strangulation and perforation. Case Report: A 6-year old girl was referred from a regional hospital for haematemesis and abdominal pain. She had fever and sepsis. Physical examination revealed abdominal tenderness, rebound and failure to thrive. Air-fluid level was seen in the posterior of left hemithorax at the AP and lateral chest radiographs. Thorax CT demonstrated pleural fluid, opacity, volume loss and left lung being pushed to the right of heart. Stomach and splenic flexura were moved to the left hemithorax. At laparatomy, stomach and splenic flexura had passed along the esophageal hiatus toward the chest and fundus of the stomach was perforated within the hernia sac. Greater curvature and fundus of the stomach were necrotic and hernia sac and intraabdominal space was filled with food. Stomach was pulled into the abdomen. Hernia sac was excised and defect was primarly repaired. Necrotic areas of the stomach were debrided. Then, perforation of stomach was repaired and gastrostomy was performed. Control esophagogastroduodenography revealed a 2 cm filling defect at the greater curvature and fundus of stomach due to previous gastric resection. Antireflux medical treatment was successful.Conclusion: PEH may be asymptomatic and encountered incidentally. It has the potential for serious complications such as strangulation and perforation which may present with unusual symptoms and physical findings reflecting the original pathology. Due to the risk of these serious complications, elective surgical repair is necessary after diagnosis. (Jo­ur­nal of Cur­rent Pe­di­at­rics 2012; 10: 36-9

  5. Urosepsis complicated by a spontaneous bladder perforation.

    Science.gov (United States)

    Lutwak, Nancy; Dill, Curt

    2011-11-08

    The authors present a case of a 72-year-old diabetic male s/p pelvic irradiation for prostate carcinoma who arrived in the emergency department with complaints of shaking chills. After admission for urosepsis, he developed severe abdominal pain and examination revealed a diffusely tender abdomen. The patient was diagnosed with spontaneous urinary bladder perforation and underwent surgery. After several weeks of intravenous antibiotics, he was discharged with multiple drains in place and bilateral nephrostomy tubes.

  6. Traumatic Tympanic Membrane perforation: An aetiological profile

    Directory of Open Access Journals (Sweden)

    Alabi Biodun S

    2009-11-01

    Full Text Available Abstract Background Traumatic perforation of the tympanic membrane may be due to direct or indirect source. The aim of the study is to profile the various aetiologies of traumatic tympanic membrane perforation in Ilorin, north central Nigeria. A retrospective review of 64 patients seen at the University of Ilorin Teaching hospital, Ilorin, Nigeria over a ten year period (January 1998 to Dec 2007 with history of traumatic tympanic membrane perforation from various causes, these also included multiply injured patients with bleeding from middle ear as part of their presentations. The data retrieved included the biodata, the clinical presentations, source of injury, the clinical findings and the treatment outcome. The data were entered into an SPSS version 11 computer soft ware and analyzed descriptively. Findings Sixty four (64 ears were analysed, Age range 6 months to 50 yrs, mean age of 29.2 yrs 7.9% of them were ≤5 years, 29.7% between 21-34 years, and 37.7% were 35 years and above. The male to female ratio was 2.5:1.0. Commonest aetiology was from slaps, then road traffic injury (RTI in 35.9% and 23.5%, Majority of the slap injury were from fights (30.5%, security agents, senior students and cultists at schools (17.4% each. Sudden hearing loss was a typical presentation (95.3%, majority of the patient defaulted from follow up once the symptoms of bleeding and pain subsided. Only 7.8% had neomembrane formation on follow up Conclusion Traumatic perforation of the tympanic membrane is an uncommon injury that is under-reported, there is the need to educate on alternative punitive measure among students and security agents, unskilled removal of foreign body, early identification, evaluation and referral of patients reduces the attendant morbidity.

  7. PERFORATED PEPTIC ULCER: A CLINICAL ANALYSIS AND OUTCOME

    Directory of Open Access Journals (Sweden)

    Bijit

    2016-03-01

    Full Text Available BACKGROUND The incidence of perforated peptic ulcer is approximately 7-10 cases per one lakh population per year. Perforation is seen in about 7% of patients hospitalized for peptic ulcer disease. Peptic ulcer perforation, which can be gastric/duodenal perforation can be a serious life-threatening condition if not detected early and treated urgently. Peptic ulcer disease has decreased considerably worldwide with the advent of potent anti-ulcer medicines, but its complication like peptic ulcer perforation has not. Our study is to analyse the clinical, radiological and management related findings in influencing the outcome of patients of peptic ulcer perforation after surgery. MATERIALS AND METHODS A series of 47 patients of peptic ulcer perforation were evaluated. Patients expiring within six hours of admission were not included in this study. RESULTS Age of the patients ranged from 17-80 years. The incidence of perforation was highest in the age group of 41-50 years (31.9%. Out of 47 patients, 41 (87.2% survived. CONCLUSION The incidence of perforation was highest in the age group of 41-50 years. Prognosis becomes poor with age, delayed treatment, shock at admission and concomitant diseases. Direct repair of the perforation with pedicled omentum gave excellent results.

  8. Typhoid ileal perforation: a 13-year experience

    Directory of Open Access Journals (Sweden)

    Poras Chaudhary

    2015-07-01

    Full Text Available Typhoid fever is endemic in many developing countries with a high rate of complications. Aim of this study is to analyse epidemiological features, clinical presentations, complications and therapeutic outcomes of enteric perforation peritonitis diagnosed and treated in our hospital. Records of total number of 646 patients, who presented with perforation peritonitis due to enteric fever in the surgical emergency unit of Dr Ram Manohar Lohia hospital, New Delhi between January 2001 and December 2013, were reviewed retrospectively. Descriptive statistics was used to analyze the data. Out of 646 patients, 62 (9.59% presented in shock. Stomal, peristomal, local and systemic complications were high in these patients. Primary closure was done in 212 (33.12 patients, primary ileostomy was created in 410 (64.06 patients, and resection and anastomosis was done in 24 (3.75 patients. Thirteen patients (2.01% died of typhoid intestinal perforation. To prevent complications of typhoid fever, in addition to control sanitation, it is also important to control quackery and malpractices. Awareness and education about the disease, its nature and complications will also be of great help.

  9. Tuberculous gastric perforation: report of a case.

    Science.gov (United States)

    Sharma, Deborshi; Gupta, Arun; Jain, Bhupendra Kumar; Agrawal, Vivek; Dargan, Puneet; Upreti, Lalendra; Arora, Vinod

    2004-01-01

    A 21-year-old woman presented with a 2-day history of acute abdominal pain. Contrast-enhanced computed tomography (CT) showed a perforation in the lesser curve of the stomach. The patient suffered a bout of hematemesis, following which an endoscopy showed a bleeding blood vessel at the edge of the perforation. We performed an emergency distal gastrectomy, including the ulcer site. Histopathological examination revealed tuberculous granulation tissue and acid-fast bacilli in the ulcer. The patient was given antituberculosis therapy (ATT) postoperatively, and was well when last seen 1 year 5 months after surgery. We analyzed the clinical data of five cases of tuberculous gastric perforation (TGP), reported between 1948 and 2003, including our patient. The patients ranged in age from 21 to 45 years, with a mean age of 36.8 years (SD +/- 10.21), and a male to female ratio of 3 : 2. The diagnosis was confirmed by surgery or autopsy. Abdominal lymphadenopathy was present in all patients. Gastrectomy was performed in four patients, and two were given ATT. All four patients in the previous reports died of their disease.

  10. Medical image of the week: eosphageal perforation

    Directory of Open Access Journals (Sweden)

    Bilal J

    2015-04-01

    Full Text Available No abstract available. Article truncated after 150 words. A 74 year old man with a past medical history of esophageal strictures status post dilatation, coronary artery disease status post CABG, and atrial fibrillation presented to hospital with complaints of severe chest pain that began after the consumption of tortilla chips one hour prior to presentation. Electrocardiogram and cardiac enzymes were not consistent with acute coronary syndrome. Chest X-ray was consistent with a widened mediastinal silhouette. Contrast esophogram was negative for extra luminal extravasation. CT scan of the chest with oral contrast demonstrated thickening of the mid-thoracic esophagus with an extra-luminal focus of gas in the mediastinum along with fluid along the inferior aspect of the esophagus (Figures 1 and 2. These findings were concerning for esophageal perforation. The patient was taken to the operating room for endoscopy which showed micro perforation in mid-esophagus. Esophageal perforation remains a highly morbid condition. Mortality rates are based predominantly on time of ...

  11. Perforated jejunal diverticula: a case report

    Directory of Open Access Journals (Sweden)

    Collins Christopher G

    2010-06-01

    Full Text Available Abstract Introduction Jejunal diverticula are rare and are usually asymptomatic. However, they may cause chronic non-specific symptoms or rarely lead to an acute presentation. Case presentation We report the case of an 82-year-old Caucasian woman presenting with a one-day history of generalized abdominal pain, with three episodes of vomiting. An abdominal X-ray displayed multiple dilated loops of the small bowel. A subsequent computed tomography scan of the abdomen and pelvis revealed a thickening of the duodenum and dilatation of the proximal jejunum. Multiple small bowel diverticula were identified with surrounding pockets of free air adjacent to the jejunal diverticula suggestive of a small bowel perforation. Our patient underwent a laparotomy, which identified multiple jejunal diverticula with two pinhole jejunal perforations and associated fecal contamination. The perforations were repaired with primary closure and extensive washout was performed. Conclusion Jejunal diverticulosis in the elderly can lead to significant morbidity and mortality and so should be suspected in those presenting with crampy abdominal pain and altered bowel habits.

  12. [Perforated duodenal diverticulum: report of a case].

    Science.gov (United States)

    Gulotta, G; Agosta, G; Romano, G

    2001-01-01

    After the colon, the duodenum is the most common site of diverticula. Duodenal diverticula can be divided into two types: intraluminal or extraluminal. The latter are more frequent, with a prevalence ranging from 0.6 to 27% in relation to the diagnostic methods utilized. Females are more often affected than males. About 70-75% of extraluminal duodenal diverticula are located in a circular area centred around the ampulla of Vater within a radius of 2-3 cm; these are defined as periampullary or juxtapapillary. Perforation is the rarest type of complication and can simulate different clinical conditions. CT plays a fundamental role in diagnosis also in relation to the different diverticular topography. Perforation is an indication for emergency surgery. The authors describe the clinical case of a duodenal diverticulum containing the outlet of the papilla, complicated by perforation; CT showed retroduodenal fluid and free air. Emergency surgery with an external biliary drainage, naso-biliary probe, and a diverticulo-jejunostomy on a Roux-en-Y defunctionalised loop, resolved the condition.

  13. Radiographic evaluation of furcal perforations sealed with different materials in dogs' teeth

    Directory of Open Access Journals (Sweden)

    José Roberto Vanni

    2011-08-01

    Full Text Available OBJECTIVE: The objective of this work was to evaluate, using radiographic images, the behavior of four materials used to repair root perforations in dogs' teeth. Material and METHODS: Second and third premolars of 6 dogs were used. The 48 teeth were randomly divided into 4 groups (n=12 and the perforations were sealed with one of the following materials: MTA, AH Plus, Vitremer and gutta-percha. Dogs were submitted to general anesthesia, teeth were radiographed and pulp was accessed. Perforations were done, at the maximum curve of the pulp floor, sealed and the accessed coronal cavity was filled with glass ionomer cement (Vidrion R. After 90 days, the dogs were sacrificed and the last x-ray image was taken. Images were analyzed for the presence/absence of periodontal lesions at the perforation region. Data were analyzed statistically by chi-square test at 5% significance level. RESULTS: There were no statistically significant differences (p>0.05 among AH Plus, Vitremer and gutta-percha groups. MTA produced the smallest number of periodontal lesions (p<0.05. CONCLUSIONS: It may be concluded that none of the tested materials was able to preserve the integrity of the periodontal tissues in the furcation region, and the use of MTA resulted in the least formation of adjacent periodontal bone lesions revealed by the radiographic comparisons.

  14. Improvement of Date Palm Fibre Acoustic Properties Using Perforated Plate, Woven Cotton Cloth and Polyester

    Directory of Open Access Journals (Sweden)

    Lamyaa Abd AL Rahman

    2013-12-01

    Full Text Available The aim of this study was to explore the effect of date palm fibre as backing on sound absorption using three types of perforation plates and porous layers. The predicted results were verified by measurements conducted in an impedance tube on normal incidence sound absorption of 30 and 50 mm-thick date palm fibre and backing that may have positive effect are elaborated in this study. It describes how the porous materials of date palm fibre absorber panel can change the absorption behavior. The results obtained show that perforation plate, porous layers have a significant effect on absorption, whereas thickness panel have considerable effect too. This further indicate that three types have been used and also supported can be powerfully exploited to improve the absorption of date palm fibre and at the same time a reasonable thickness chosen, would be very efficient for absorption sound. An example is presented to show the approaches of enhancing the absorption, by utilizing the advantage of modification in the absorption sound. It exhibits that properly chosen perforation ratio along with suitable sample thickness can increase the absorption as well as the selected porous layers. It was evident that these can be powerfully exploited to improve the absorption of date palm fibre. Three types of perforation plate, porous layers were used to improve acoustic properties of date palm fibre. This means the innovative fibre becomes more active and efficient, plus it is renewable, waste material and very light compared to industrial substances.

  15. Design of Bridge Expansion Joints with Perforated Dowels Under Impact Loading

    Institute of Scientific and Technical Information of China (English)

    YODA Teruhiko; AYASHI Mamiko

    2008-01-01

    The expansion joints are expected to have movement capacity.bearing capacity for stahc and dynamic loading,water-tightness,low noise emission and traffic safety.In particular.the tailure due to impact loading is the main reason for the observed damaaes.The problem of dynamic behavior of the expansion joints is so complex that we shall focus our attention on the impact factor for vehicle load that is governed by traffic impact.In order to overcome this difficulty. the cantilever-toothed aluminum joint(finger joint)is one of the promising joints under impact load-ing.In this study,from the viewpoint of design methodology.numerical studies for impact be-havior were conducted for aluminum alloy expansion joints with perforated dowels.The design im-pacf factor for the expansion joints with the perforated dowels against traffic impact loading was examined by using numerical simulations.

  16. Effects of torsional degree of freedom, geometric nonlinearity, and gravity on aeroelastic behavior of large-scale horizontal axis wind turbine blades under varying wind speed conditions

    DEFF Research Database (Denmark)

    Jeong, Min-Soo; Cha, Myung-Chan; Kim, Sang-Woo

    2014-01-01

    Modern horizontal axis wind turbine blades are long, slender, and flexible structures that can undergo considerable deformation, leading to blade failures (e.g., blade-tower collision). For this reason, it is important to estimate blade behaviors accurately when designing large-scale wind turbines....... In this study, a numerical analysis considering blade torsional degree of freedom, geometric nonlinearity, and gravity was utilized to examine the effects of these factors on the aeroelastic blade behavior of a large-scale horizontal axis wind turbine. The results predicted that flapwise deflection is mainly...... affected by the torsional degree of freedom, which causes the blade bending deflections to couple to torsional deformation, thereby varying the aerodynamic loads through changes in the effective angle of attack. Edgewise deflection and torsional deformation are mostly influenced by the periodic...

  17. Large-distance and long-time asymptotic behavior of the reduced density matrix in the non-linear Schroedinger model

    Energy Technology Data Exchange (ETDEWEB)

    Kozlowski, K.K.

    2010-12-15

    Starting from the form factor expansion in finite volume, we derive the multidimensional generalization of the so-called Natte series for the zero-temperature, time and distance dependent reduced density matrix in the non-linear Schroedinger model. This representation allows one to read-off straightforwardly the long-time/large-distance asymptotic behavior of this correlator. Our method of analysis reduces the complexity of the computation of the asymptotic behavior of correlation functions in the so-called interacting integrable models, to the one appearing in free fermion equivalent models. We compute explicitly the first few terms appearing in the asymptotic expansion. Part of these terms stems from excitations lying away from the Fermi boundary, and hence go beyond what can be obtained by using the CFT/Luttinger liquid based predictions. (orig.)

  18. Temperature-dependent differences in the nonlinear acoustic behavior of ultrasound contrast agents revealed by high-speed imaging and bulk acoustics.

    Science.gov (United States)

    Mulvana, Helen; Stride, Eleanor; Tang, Mengxing; Hajnal, Jo V; Eckersley, Robert

    2011-09-01

    Previous work by the authors has established that increasing the temperature of the suspending liquid from 20°C to body temperature has a significant impact on the bulk acoustic properties and stability of an ultrasound contrast agent suspension (SonoVue, Bracco Suisse SA, Manno, Lugano, Switzerland). In this paper the influence of temperature on the nonlinear behavior of microbubbles is investigated, because this is one of the most important parameters in the context of diagnostic imaging. High-speed imaging showed that raising the temperature significantly influences the dynamic behavior of individual microbubbles. At body temperature, microbubbles exhibit greater radial excursion and oscillate less spherically, with a greater incidence of jetting and gas expulsion, and therefore collapse, than they do at room temperature. Bulk acoustics revealed an associated increase in the harmonic content of the scattered signals. These findings emphasize the importance of conducting laboratory studies at body temperature if the results are to be interpreted for in vivo applications.

  19. Premixed Combustion of Kapok (ceiba pentandra) seed oil on Perforated Burner

    OpenAIRE

    I.K.G. Wirawan; I. N. G. Wardana; Rudy Soenoko; Slamet Wahyudi

    2014-01-01

    Availability of fossil fuels in the world decrease gradually due to excessive fuel exploitation. This situations push researcher to look for alternative fuels as a source of renewable energy, one of them is kapok (ceiba pentandra) seed oil. The aim this study was to know the behavior of laminar burning velocity, secondary Bunsen flame with open tip, cellular and triple flame. Premixed combustion of kapok seed oil was studied experimentally on perforated burner with equivalence ratio (φ) varie...

  20. Gallbladder perforation complicating typhoid fever: report of two cases.

    Science.gov (United States)

    Gali, B M; Ali, N; Agbese, G O; Duna, V D; Dawha, S D; Ismai, G I; Mohammed, M

    2011-01-01

    Gallbladder perforation (GBP) is rare and as a complication of typhoid fever is extremely rare. We present two consecutive patients with GBP diagnosed incidentally at laparotomy. Information on the management of two patients with gallbladder perforation seen at Federal Medical Centre Azare in June and October 2008 was extracted from their case records. The two patients were both males aged 13 years and 16 years. They both presented with high fever of more than 2 weeks duration; and abdominal pain and distension. Both patients had features of generalised peritonitis. Pre-operative diagnoses of typhoid enteric perforation were made based on a positive Widal test. Intra-operative findings however, were that of bile peritonitis and gallbladder perforation. Both had cholecystectomy. Culture of the bile aspirate yielded Salmonella typhi. Gallbladder perforation secondary to typhoid fever should be considered as a differential diagnosis in patients with suspected typhoid enteric perforation in typhoid fever endemic region.

  1. Catheter perforation of distal oesophagus with duodenal re-entry of catheter. Report of a case

    Energy Technology Data Exchange (ETDEWEB)

    Bundgaard, T.; Kristensen, H.; Lesak, F.

    An unusual case of perforation of the oesophagus is presented. A nasogastric tube had perforated the oesophagus and re-penetrated into the duodenum, and thereby re-entered the gastrointestinal tract without perforating the peritoneum and without causing the classical clinical signs of oesophageal perforation. Treatment was started 31 days after the perforation.

  2. Periodic behavior of collapse-revival phenomenon in the full nonlinear interaction between a three-level atom and a single-mode field

    Science.gov (United States)

    Tavassoly, M. K.; Rastegarzadeh, M.

    2016-10-01

    In this paper based on a generalization of the Jaynes-Cummings model we solve the dynamical Hamiltonian describing the interaction between a (Λ or V-type) three-level atom and a single-mode field in the "full nonlinear regime" and then the analytical form of state vector of the system is explicitly obtained. In this manner, we encountered with "intensity-dependent detuning" as well as "intensity-dependent atom-field coupling" in our two models. Via choosing an appropriate deformation function (which imposes nonlinearity to the system) we consider the influence of Kerr-like medium from which the resonance condition for a selected number of quanta is achieved (selective transition is occurred). Furthermore, by these considerations, we may find the optimum values for atom-field coupling constants which provide a regular periodic behavior of probability amplitudes for the two considered atomic systems. Moreover, to show this periodic time behavior, the temporal evolution of the probability of the allowed atomic transitions as well as the Mandel parameter (as a non-classical sign) is depicted for various circumstances. As is observed, complete revivals may appear in some particular situations.

  3. Low-Cost Control Problems on Perforated and Non-Perforated Domains

    Indian Academy of Sciences (India)

    S Kesavan; T Muthukumar

    2008-02-01

    We study the homogenization of a class of optimal control problems whose state equations are given by second order elliptic boundary value problems with oscillating coefficients posed on perforated and non-perforated domains. We attempt to describe the limit problem when the cost of the control is also of the same order as that describing the oscillations of the coefficients. We study the situations where the control and the state are both defined over the entire domain or when both are defined on the boundary.

  4. ON THE MODIFIED NONLINEAR SCHR(O)DINGER EQUATION IN THE SEMICLASSICAL LIMIT:SUPERSONIC, SUBSONIC, AND TRANSSONIC BEHAVIOR

    Institute of Scientific and Technical Information of China (English)

    Jeffery C. DiFranco; Peter D. Miller; Benson K. Muite

    2011-01-01

    The purpose of this paper is to present a comparison between the modified nonlinear Schr(o)dinger (MNLS) equation and the focusing and defocusing variants of the (unmodified) nonlinear Schr(o)dinger (NLS) equation in the semiclassical limit.We describe aspects of the limiting dynamics and discuss how the nature of the dynamics is evident theoretically through inverse-scattering and noncommutative steepest descent methods.The main message is that,depending on initial data,the MNLS equation can behave either like the defocusing NLS equation,like the focusing NLS equation (in both cases the analogy is asymptotically accurate in the semiclassical limit when the NLS equation is posed with appropriately modified initial data),or like an interesting mixture of the two.In the latter case,we identify a feature of the dynamics analogous to a sonic line in gas dynamics,a free boundary separating subsonic flow from supersonic flow.

  5. Perforated duodenal diverticulum caused by Bezoar: A case report

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eun Jung; Moon, Sung Kyoung; Park, Seong Jin; Lim, Joo Won; Lee, Dong Ho; Ko, Young Tae [Dept. of Radiology, College of Medicine, Kyung Hee University, Seoul (Korea, Republic of)

    2013-11-15

    Duodenal diverticulum is common, but its perforation is a rare complication. Duodenal diverticulum perforation requires prompt treatments because of its high mortality rate. However, an accurate diagnosis is difficult to make due to nonspecific symptoms and signs. It can be misdiagnosed as pancreatitis, cholecystitis, or peptic ulcer. Herein, we report a case of perforated duodenal diverticulum caused by bezoar in a 33-year-old woman whom was diagnosed by abdomen computed tomography and ultrasonography.

  6. Typhoid perforation of small bowel: a study of 72 cases.

    Science.gov (United States)

    Noorani, M A; Sial, I; Mal, V

    1997-08-01

    Typhoid perforation, a serious complication of typhoid fever, is still common in Third World countries and has a mortality rate between 1 and 39.3% according to various reports. There are different approaches to the treatment of typhoid perforation. Early surgical intervention with simple closure of the perforation in two layers has good results and negligible mortality. It is easy to perform and can be carried out, even by a trainee surgeon.

  7. Low Voltage Electric Current Causing Ileal Perforation: A Rare Injury

    Science.gov (United States)

    Mathur, Vinay; Tanger, Ramesh; Gupta, Arun Kumar

    2016-01-01

    Post-electric burn ileal perforation is a rare but severe complication leading to high morbidity and mortality if there is delay in diagnosis and management. We are describing a case of electric current injury of left forearm, chest, and abdominal wall with perforation of ileum in an 8-year old boy. Patient was successfully managed by primary closure of the ileal perforation. PMID:27170922

  8. Perforation of the duodenum by an ingested toothbrush

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    We report a rare case of duodenal perforation caused by an ingested 12-cm long toothbrush handle. A 22-year-old female presented with intermittent epigas- tric pain for 6 d after swallowing a broken toothbrush. The swallowed toothbrush could not be removed from the second portion of the duodenum by endoscopy. Laparotomy revealed a perforation in the anterior wall of the duodenal bulb. The toothbrush was removed via the perforation which was debrided and closed. There were no postoperative complications.

  9. Perforation of the duodenum by an ingested toothbrush

    OpenAIRE

    Chao, Hsiao-Hsiang; Chao, Tzu-Chieh

    2008-01-01

    We report a rare case of duodenal perforation caused by an ingested 12-cm long toothbrush handle. A 22-year-old female presented with intermittent epigastric pain for 6 d after swallowing a broken toothbrush. The swallowed toothbrush could not be removed from the second portion of the duodenum by endoscopy. Laparotomy revealed a perforation in the anterior wall of the duodenal bulb. The toothbrush was removed via the perforation which was debrided and closed. There were no postoperative compl...

  10. Dorsolateral musculocutaneous perforators of posterior intercostal artery: an anatomical study.

    Science.gov (United States)

    Prasad, Vani; Almutairi, Khalid; Kimble, Frank W; Stewart, Fiona; Morris, Steven F

    2012-11-01

    The posterior intercostal artery (PICA) is divided into four segments, vertebral, costal, intermuscular, and rectus, based on the neurovascular branching pattern. Dorsal branches arise from the vertebral segment. Several musculocutaneous perforators and a lateral branch originate from the costal segment. Musculocutaneous branches arise from the intermuscular and rectus segments. The purpose of this study is to describe in detail the musculocutaneous perforators of the costal segment of the posterior intercostal artery. Fresh cadavers were injected with a modified lead oxide-gelatin mixture. Intercostal spaces (8-11) were dissected in twelve cadavers (six preserved cadavers and six fresh cadavers). Angiograms were assembled with Adobe Photoshop. Two fresh cadavers underwent CT angiography and three dimensional reconstructions of the intercostal perforators were performed using Materialise's Interactive Medical Image Control System (MIMICS). In twelve cadavers, a total of 356 perforators (size > 0.5 mm) were found to arise from the posterior intercostal arteries in 96 intercostal (IC) spaces. 154 perforators (>0.5 mm) were found in the costal segment of the PICA. An average of 6.4 perforators was found in each hemithorax. All perforators were found within 2 cm of the midscapular line. At least one perforator was found in all intercostal spaces. Two or more perforators were found in 40% of the 8th and 9th IC spaces and 60% of the 10th and 11th IC spaces. Perforators were oriented perpendicular to the direction of the muscle fibres of the latissimus dorsi and were usually present one or two intercostal spaces below their origin from the PICA. Perforators of the costal segment of the PICA are described in detail. We propose to call these currently unnamed musculocutaneous perforators "dorsolateral" branches of the PICA, as they are located between dorsal and lateral branches of PICA. Copyright © 2012 British Association of Plastic, Reconstructive and Aesthetic Surgeons

  11. Low Voltage Electric Current Causing Ileal Perforation: A Rare Injury

    Directory of Open Access Journals (Sweden)

    Aditya Pratap Singh

    2016-04-01

    Full Text Available Post-electric burn ileal perforation is a rare but severe complication leading to high morbidity and mortality if there is delay in diagnosis and management. We are describing a case of electric current injury of left forearm, chest, and abdominal wall with perforation of ileum in an 8-year old boy. Patient was successfully managed by primary closure of the ileal perforation.

  12. A study on the seismic behavior of a retrofitted building based on nonlinear static and dynamic analyses

    Institute of Scientific and Technical Information of China (English)

    Esra Mete Güneyisi; Gülay Altay

    2005-01-01

    This study describes the seismic performance of an existing five storey reinforced concrete building which represents the typical properties of low-rise non-ductile buildings in Turkey. The effectiveness of shear walls and the steel bracings in retrofitting the building was examined through nonlinear static and dynamic analyses. By using the nonlinear static analysis, retrofitted buildings seismic performances under lateral seismic load were compared with each other.Moreover, the performance points and response levels of the existing and retrofitting cases were determined by way of the capacity-spectrum method described in ATC-40 (1996). For the nonlinear dynamic analysis the records were selected to represent wide ranges of duration and frequency content. Considering the change in the stiffness and the energy dissipation capacities, the performance of the existing and retrofitted buildings were evaluated in terms of story drifts and damage states.It was found that each earthquake record exhibited its own peculiarities, dictated by frequency content, duration, sequence of peaks and their amplitude. The seismic performance of retrofitted buildings resulted in lower displacements and higher energy dissipation capacity depending mainly on the properties of the ground motions and the retrofitting strategies. Moreover,severe structural damage (irreparable or collapse) was observed for the existing building. However, buildings with retrofit alternatives exhibited lower damage levels changing from no damage to irreparable damage states.

  13. PERFORATION OF PLASTIC SPHERICAL SHELLS UNDER IMPACT BY CYLINDRICAL PROJECTILES

    Institute of Scientific and Technical Information of China (English)

    NING Jian-guo; SONG Wei-dong

    2006-01-01

    The objective is to study the perforation of a plastic spherical shell impacted by a cylindrical projectile. First, the deformation modes of the shell were given by introducing an isometric transformation. Then, the perforation mechanism of the shell was analyzed and an analytical model was advanced. Based on Hamilton principle, the governing equation was obtained and solved using Runge-Kuta method. Finally, some important theoretical predictions were given to describe the perforation mechanism of the shell. The results will play an important role in understanding the perforation mechanism of spherical shells impacted by a projectile.

  14. Spontaneous common bile duct perforation due to periampullary growth

    Directory of Open Access Journals (Sweden)

    Pandiaraja Javabal

    2014-06-01

    Full Text Available Spontaneous common bile duct perforations are an unusual cause of acute abdomen. In spontaneous common bile duct perforation, malignant growth is even rare. It is a rare entity usually reported in infants and children due to congenital anomalies. It is rarely reported in adults. In this case report, a 55 - year - old male patient who was diagnosed as a duodenal perforation in the pre - operative period, but the intra - operative findings was common bile duct perforation due to periampullary growth, is reported

  15. Aortic Pseudoaneurysm Secondary to Mediastinitis due to Esophageal Perforation

    Directory of Open Access Journals (Sweden)

    Claudia Patricia Zuluaga

    2016-01-01

    Full Text Available Esophageal perforation is a condition associated with high morbidity and mortality rates; it requires early diagnosis and treatment. The most common complication of esophageal rupture is mediastinitis. There are several case reports in the literature of mediastinitis secondary to esophageal perforation and development of aortic pseudoaneurysm as a complication. We report the case of a patient with an 8-day history of esophageal perforation due to foreign body (fishbone with mediastinitis and aortic pseudoaneurysm. The diagnosis was made using Computed Tomography (CT with intravenous and oral water-soluble contrast material. An esophagogastroduodenoscopy did not detect the perforation.

  16. An Unusual Etiology of Spontaneous Pyometra Perforation; A Case Report

    Science.gov (United States)

    Agarwal, Rachna; Suneja, Amita; Sharma, Abha; Vaid, Neelam Bala

    2011-01-01

    Introduction By presenting this case we aimed to describe an uncommon complication of generalized peritonitis following spontaneous pyometra perforation in untreated cervical carcinoma. Case Presentation This report describes a 60-year-old postmenopausal woman presenting with clinical features mimicking intestinal perforation who was later diagnosed as cervical carcinoma with pyometra perforation at exploratory laparotomy. The patient had good post-operative recovery following drainage and peritoneal lavage. Conclusion Spontaneous pyometra perforation in a case of untreated carcinoma of cervix is a rare condition, yet it should be suspected and kept in the differential diagnosis of acute abdomen in elderly women. PMID:23926508

  17. Imaging gastrointestinal perforation in pediatric blunt abdominal trauma

    Energy Technology Data Exchange (ETDEWEB)

    Jamieson, D.H. [Department of Diagnostic Imaging, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G 1X8 (Canada); Babyn, P.S. [Department of Diagnostic Imaging, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G 1X8 (Canada); Pearl, R. [Department of Diagnostic Imaging, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G 1X8 (Canada)

    1996-03-01

    Objective. To assess the role of imaging, in particular CT, in the early detection of GI perforation. Subjects and methods. In a 10-year period, 43 patients with surgically confirmed GI perforation were identified from hospital records; 22 of these had preoperative CT evaluation. Medical records and radiology were retrospectively reviewed and CT studies were particularly assessed for extraluminal air, free intraperitoneal fluid, bowel wall thickening, bowel wall enhancement, and bowel dilatation. During the study period an additional 12 trauma patients were identified who had CT studies demonstrating the above findings, but who had hypovolemic shock bowel or nondisrupting bowel injury without perforation evident. Results. Extraluminal air was demonstrated in 47 % of the imaged perforations. There was one false-positive extraluminal air. Perforation was confirmed in patients who had all five of the above CT findings, but this was the case for only 18 % of patients with perforation. One or more of the five specified CT findings were present in all CT studies reviewed. No false-negative CT study was performed in the study period. Conclusion. Separating nondisrupting bowel injury from perforation is diagnostically difficult; however, CT remains a good modality for assessing GI perforation in pediatric blunt trauma, but it cannot replace diligent and repeated clinical evaluation of all potential perforation victims. (orig.). With 4 figs., 1 tab.

  18. Aeroacoustics of a wall perforation in the pure grazing flow regime: effect of the perforation geometry

    NARCIS (Netherlands)

    Tonon, D.; Moers, E.M.T.; Golliard, J.; Hirschberg, A.

    2012-01-01

    Acoustical dampers are used in order to avoid the noise propagation. Well known examples are the aero-engine liners, the IC-engine exhaust muffers, and the liners in combustion chambers. These devices comprise wall perforations, responsible for their sound absorbing features. Understanding the effec

  19. Perforator-to-perforator musculocutaneous anterolateral thigh flap for reconstruction of a lumbosacral defect using the lumbar artery perforator as recipient vessel.

    Science.gov (United States)

    Mureau, Marc A M; Hofer, Stefan O P

    2008-05-01

    Reconstruction of large-sized lumbosacral or sacral defects often is not possible using local or regional flaps, making the use of free flaps necessary. However, the difficulty of any microsurgical procedure in this region is complicated by the need to search for potential recipient vessels to revascularize the flap. In the present case, a free musculocutaneous anterolateral thigh flap to cover a large-sized and deep lumbosacral defect was used. Arterial anastomosis was performed, connecting the cutaneous anterolateral thigh (ALT) perforator to the perforator of the second lumbar artery. In this fashion, the arterial circulation through the flap was flowing reversely through the muscle. The concomitant vein of the descending branch of the lateral circumflex femoral artery was hooked up to the thoracodorsal vein using a long interposition vein graft because the perforator of the second lumbar vein was too small. Postoperative healing was uneventful. In conclusion, a successful reconstruction of a lumbar defect has shown that local perforators in the lumbar area may be accessible for easier perforator-to-perforator anastomoses and that the muscular part of the musculocutaneous ALT flap can survive on retrograde arterial perfusion from a perforator of the skin island.

  20. Bladder Perforation Secondary to Primary Systemic Amyloidosis

    Directory of Open Access Journals (Sweden)

    Christopher J. Dru

    2014-01-01

    Full Text Available Amyloidosis is a disorder of protein folding characterized by extracellular aggregation and deposition of amyloid protein fibrils. Light-chain amyloidosis, also known as primary systemic amyloidosis, is the most common form of the disease. We present a case of an 84-year-old male with a history of systemic primary amyloidosis causing genitourinary, cardiac, and autonomic dysfunction who presented with hematuria and hypotension secondary to bladder perforation. He underwent open repair of a large extraperitoneal bladder defect. He ultimately died as a result of medical complications from his disease.

  1. Appendicular perforation in dengue fever: our experience

    Directory of Open Access Journals (Sweden)

    Gunjan Desai

    2014-09-01

    Full Text Available Dengue viral infections have become one of major emerging infectious diseases in the tropics. Acute abdomen occurring in dengue viral infection is not uncommon. The spectrums of acute surgical emergencies which raise suspicion of an abdominal catastrophe in patients presenting with dengue fever include acute pancreatitis, acute acalculous cholecystitis, non-specific peritonitis and very rarely acute appendicitis. The presence of low white cell count and platelet count can raise suspicion of a diagnosis of dengue in a patient presenting with acute abdominal pain, during a dengue epidemic. We herein report three patients with dengue fever who had appendicular perforation during the course of their viral fever.

  2. [Case report: intestinal perforation by foreign body].

    Science.gov (United States)

    Martínez Portilla, Karol A; Zubiri, Cecilia; Balcarce, Norma; Zosi, Anabella; Chereau, Clara I

    2017-02-01

    Accidental ingestion of foreign bodies in childhood is a common event that rarely requires interventional management and presents very few complications involving surgical treatment. We present a clinical case of a 10 month old infant, without abdominal manifestations, in whom it was incidentally found a foreign radiopaque body of 7 cm in length in the abdomen, compatible with a screw. It was not possible to extract it by endoscopy. Therefore, it was necessary to perform surgery and a perforation of the second and third portion of the duodenum was encountered.

  3. Transhepatic perforation of the gallbladder: rare complication of a common disease

    Directory of Open Access Journals (Sweden)

    Shrestha KR

    2010-05-01

    Full Text Available Acute cholecystitis leading to gallbladder perforation is relatively common. However, transhepatic perforation of the gallbladder leading to biliary peritonitis is very rare. We present a rare case of biliary peritonitis caused by transhepatic perforation of the gallbladder.

  4. Nonlinear systems in medicine.

    Science.gov (United States)

    Higgins, John P

    2002-01-01

    Many achievements in medicine have come from applying linear theory to problems. Most current methods of data analysis use linear models, which are based on proportionality between two variables and/or relationships described by linear differential equations. However, nonlinear behavior commonly occurs within human systems due to their complex dynamic nature; this cannot be described adequately by linear models. Nonlinear thinking has grown among physiologists and physicians over the past century, and non-linear system theories are beginning to be applied to assist in interpreting, explaining, and predicting biological phenomena. Chaos theory describes elements manifesting behavior that is extremely sensitive to initial conditions, does not repeat itself and yet is deterministic. Complexity theory goes one step beyond chaos and is attempting to explain complex behavior that emerges within dynamic nonlinear systems. Nonlinear modeling still has not been able to explain all of the complexity present in human systems, and further models still need to be refined and developed. However, nonlinear modeling is helping to explain some system behaviors that linear systems cannot and thus will augment our understanding of the nature of complex dynamic systems within the human body in health and in disease states.

  5. The value of CT in detecting pathologic bowel perforation

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Jong Wun; Shin, Joo Yong; Kim, Hong; Rhee, Chang Soo; Lee, Sung Moon; Joo, Yang Goo; Suh, Soo Jhi [Keimyung Univ. School of Medicine, Taegu (Korea, Republic of)

    1997-10-01

    To evaluate the usefulness of CT for assessing the location and cause of pathologic gastrointestinal perforation. A retrospective analysis of abdominal CT was performed in 27 perforations of 26 patients with underlying gastrointestinal pathology. Fifteen benign and 12 malignant perforations consisted of five gastric cancers, one gastric ulcer, ten duodenal bulb ulcers. two bowel adhesions, one jejunal metastasis from lung cancer, one ileocolic Crohn's disease, one radiation colitis and six colon cancers. CT scans were evaluated for (1) diagnosis of bowel perforation, (2) assessment of the cause and site of perforation, and, in particular, differentiation between benignancy and malignancy, and (3) complications and their extent. CT easily detected varying amounts of free air or fluid collection, and infiltration or abscess formation adjacent to the main lesion, and the diagnosis of gastrointestinal perforation was therefore easy. In 11 of the 12 malignancies (92%), primary tumor was diagnosed, but detection of the site of perforation was possible in only seven cases(7/12, 58%). The 15 benign lesions revealed nonspecific CT findings, and the perforation site could be presumed in six (6/15, 40%). In one case of Crohn's disease, the primary cause was visualized. Among six colonic cancers, four pericolic abscesses and two fistulas to adjacent organs were found, but there was no evidence of diffuse peritonitis. CT was helpful to lead to optimal treatment of pathologic gastrointestinal On CT the detectability of perforation, primary benign or malignant lesion, perforation site and extent of complication was high, and this modality was therefore a useful indicator of the optimal treatment for pathologic gastrointestinal perforations.=20.

  6. Perforation rate in acute appendicitis: association with different risk facotrs

    Directory of Open Access Journals (Sweden)

    B. Khorasani

    2006-08-01

    Full Text Available Background: The early diagnosis of acute appendicitis before progression to gangrene or abscess formation is recognized as important to minimize morbidity from this common disease process. The aim of this study was to assess the value of different risk factors in the diagnosis of perforation. Methods: This descriptive-analytic and retrospective study was conducted to investigate epidemiological characteristics in patients with perforated and non-perforated appendicitis. A series of 1311 patients who were operated on for acute appendicitis between years 1380-1382 in Shahid Beheshti and Yahya-nejad hospitals were reviewed.. Data gathered included age at operation, gender, care sought prior to admission for appendectomy including antibiotic and analgesic therapy, time of presentation in the year, duration of symptoms, signs and symptoms at the time of admission, and the patient’s living area. Results: One hundred twenty one of 1311 patients (9% had perforated appendicitis and 1190 patients (91% had unperforated appendicitis. Presentation and referral in the first 6-month was associated with higher perforation rate. Patients from rural area showed a higher rate of perforations. The perforation rate was significantly higher in elderly patients (>65 year. When the duration of symptoms was more than 12 hours at presentation, the risk of perforation showed a five-fold increase. 30.7% of perforated cases had used antibiotic or sedative before referring to the hospital. Conclusion: Appendiceal perforation continues to be a complication in patients with acute appendicitis and increased in the frequency as the age of the patients increase and the duration of symptoms lengthen. We also found that the perforation rate is higher in patients from rural area and in whom present in the first 6-month of the year, a finding that was not reported so far.

  7. Small bowel perforation caused by advanced melanoma.

    Science.gov (United States)

    den Uil, Sjoerd H; Thomassen, Irene; Vermeulen, Erik Gj; Vuylsteke, Ronald Jclm; Stockmann, Hein Bac; de Vries, Mattijs

    2014-01-01

    The incidence of melanoma has been increasing over the years and it remains, despite the heterogeneous survival for different stages, a disease with high mortality. Dissemination occurs primarily by the lymphatic route, followed by the hematogenous route. Gastrointestinal metastases do occur, but they are mainly intraluminal mucosal melanomas. Peritoneal or primary mucosal melanomas are rare. Only a few cases have been described of patients presenting with acute abdominal pain due to a melanoma. In this report we present a young patient with no prior health problems. Due to silent progression of disease at first, and secondarily avoidance of medical consultation, she finally presented to our emergency department with signs of intestinal perforation. In the operating theater a massive metastasis in the intestines with perforation was seen, as well as many smaller intra-abdominal and cutaneous lesions. Approximately 35 cm of jejunum had to be resected. Furthermore, the primary melanoma on the left forearm was excised and turned out to be in almost complete regression. Although initial recovery after surgery was good, the patient died only one month after presentation due to the advanced nature of her disease, which points to the devastating effect of undiagnosed melanoma and gastrointestinal metastasis. Since the melanoma incidence is rising, similar cases may present in the near future. This emphasizes the importance of proper full physical examination in patients with atypical abdominal symptoms.

  8. Perforation af rectum med faekal peritonitis efter staplet haemorideoperation

    DEFF Research Database (Denmark)

    Beuke, Anna-Christina; Pedersen, Mark Ellebaek; Qvist, Niels

    2008-01-01

    Rectal perforation and faecal peritonitis after stapled operation for grade IV haemorrhoids is described. The complication is rare, but surgeons performing the procedure must be familiar with potential risk factors.......Rectal perforation and faecal peritonitis after stapled operation for grade IV haemorrhoids is described. The complication is rare, but surgeons performing the procedure must be familiar with potential risk factors....

  9. The "stamp method" : a new treatment for perforated peptic ulcer?

    NARCIS (Netherlands)

    Bertleff, MJOE; Liem, RSB; Robinson, PH; Bonjer, HJ; Lange, JF; Bartels, H.; van der Werf, J.F.A.

    2006-01-01

    Background: The aim of this study was to develop a simple method for closure of a perforated peptic ulcer, making it more accessible for laparoscopic surgery. Methods: An experimental pilot study was performed using five male Wistar rats. The perforation was closed by a bioabsorbable patch made of l

  10. The Versatile Extended Thoracodorsal Artery Perforator Flap for Breast Reconstruction

    DEFF Research Database (Denmark)

    Jacobs, Jordan; Børsen-Koch, Mikkel; Gunnarsson, Gudjon Leifur;

    2016-01-01

    BACKGROUND: The thoracodorsal artery perforator (TAP) flap is a versatile tool that can be used to reconstruct the breast. The authors use preoperative perforator mapping using color Doppler ultrasonography and present a safe, efficient harvesting technique to demonstrate reliable use of the TAP...

  11. Perforated peptic ulcer disease: A review of history and treatment

    NARCIS (Netherlands)

    M.J.O.E. Bertleff (Marietta); J.F. Lange (Johan)

    2010-01-01

    textabstractBackground: In the last one hundred years much has been written on peptic ulcer disease and the treatment options for one of its most common complications: perforation. The reason for reviewing the literature was evaluating most common ideas on how to treat perforated peptic ulcers (PPU)

  12. [Retroperitoneal perforations of the colon. Apropos of 2 cases].

    Science.gov (United States)

    Jurczak, F; Likholatnikov, D; Courant, O; Hamy, A; Visset, J; Paineau, J

    1994-01-01

    The retroperitoneal perforation of the colon is rare and our observations illustrate its two modes of revelation: a retroperitoneal suppuration; it must be traited quickly in order to decrease the mortality. Note that the abscess of the thigh is exceptional. Retroperitoneal perforations during colonoscopy whose treatment (initially medical) become surgical if there is no clinical improvement.

  13. Taenia saginata: A Rare Cause of Gall Bladder Perforation

    Directory of Open Access Journals (Sweden)

    Suhail Yaqoob Hakeem

    2012-01-01

    Full Text Available We report a case of biliary peritonitis caused by gall bladder perforation due to Taenia saginata induced gangrenous cholecystitis. Although parasites are not unusual causes of biliary tract disorders, especially in disease endemic areas, but this is for the first time that Taenia saginata has been reported to cause gall bladder perforation.

  14. CLINICAL STUDY AND MANAGEMENT OF PERITONITIS SECONDARY TO GASTROINTESTINAL PERFORATION

    Directory of Open Access Journals (Sweden)

    Karbhari

    2014-03-01

    Full Text Available Perforation peritonitis is the most common surgical emergency in India. Peritonitis due to upper gastrointestinal tract perforation constitutes majority of these cases. Despite advances in surgical techniques, antimicrobial therapy and intensive care support, management of peritonitis continues to be highly demanding, difficult and complex. . In contrast to western countries where lower gastro-intestinal tract perforations predominate, upper gastro intestinal tract perforations constitute the majority of cases in India1. Earlier Rawlinson in the year 1727 was the first to give a clear description of the signs and symptom of gastric ulcer and peritonitis.2 MATERIALS AND METHODS: All patients having GI perforation admitted in all surgical units of Basaweshwar Teaching and General Hospital, Gulbarga were considered for the study. A total of 50 cases were studied over a period of 18 months from Dec 2009 to May 2011.Data was entered in the proforma made for the study and analyzed RESULTS &CONCLUSION: Patient group more than 50yrs were the most commonly affected group and duodenal ulcer perforation (60% was the most common. Males (92% were affected more than females. Most common symptom was vomiting (68%. Guarding and rigidity were present in 90% patients. Laparotomy with closure of the perforation with omental patch is the commonest operative management for perforated peptic ulcer. The overall mortality was 4%

  15. Computed Tomography Features of Spontaneously Perforated Pyometra: A Case Report

    Energy Technology Data Exchange (ETDEWEB)

    Chan, K.S.; Tan, C.K.; Mak, C.W.; Chia, C.C.; Kuo, C.Y.; Yu, W.L. [Chi-Mei Medical Center, Tainan, Taiwan (China). Depts. of Intensive Care Medicine, Radiology, Obstetrics and Gynecology, and Surgery

    2006-03-15

    Spontaneous perforation of pyometra is an extremely rare emergent gynecologic disease. We report a 73-year-old woman with a spontaneously perforated pyometra presenting with acute abdomen in the emergency department. A dedicated computed tomography examination of the abdominal and pelvic regions revealed the diagnosis. The patient recovered well after surgical intervention and antibiotic treatment.

  16. A rare manifestation of perforated diverticulitis: parastomal subcutaneous abscess.

    NARCIS (Netherlands)

    Peters, J.H.; Bleichrodt, R.P.; Goor, H. van

    2003-01-01

    Perforation is a serious complication of diverticular disease. The sigmoid is the main affected anatomic site of perforated diverticulitis and sigmoid resection followed either by Hartmann procedure or primary anastomosis are the standard surgical approaches. Surgery, however, does not cure divertic

  17. Clinical analysis of risk factors for ERCP-related perforation

    Directory of Open Access Journals (Sweden)

    ZHOU Haihua

    2014-12-01

    Full Text Available ObjectiveTo evaluate the causes, diagnostic and therapeutic principles, and prevention of the perforation related to endoscopic retrograde cholangiopancreatography (ERCP. MethodsAll patients who developed perforation after ERCP in the Central Hospital of Shanghai Jiading District from January 2009 to December 2013 were recruited. The causes, types, and diagnosis and treatment of perforation were analyzed retrospectively. ResultsERCP was done in 459 cases during the 4 years, and 6 (1.3% of them developed perforation. The causes of perforation were as follows: endoscope insertion (3 cases, catheterization or sphincterotomy (2 cases, and guide wire or Dormia basket (1 case. Two cases received conservative management successfully and were discharged; four cases underwent surgical treatment, and one of them died. Conclusion Patients with ERCP-related perforation can achieve ideal prognosis through individualized treatment based on the causes and types of perforation. Careful and cautious operation, especially for the elderly or the patients with a history of upper abdominal operation, will reduce the incidence of ERCP-related perforation.

  18. Jejunal diverticula — a rare cause of intestinal perforation

    OpenAIRE

    Borgaonkar, Viraj; Borgaonkar, Vijay

    2009-01-01

    Jejunal diverticuli is a extremely rare entity. We report a case of jejunal diverticulum as a cause of perforation peritonitis, which has been managed by resection anastomosis. This study is important from the perspective that clear cut guidelines for managment of jejunal perforation are not available in litreture.

  19. Photoelastic stress analysis in perforated (Rochette) resin bonded bridge design.

    Science.gov (United States)

    Ziada, H M; Orr, J F; Benington, I C

    2000-05-01

    Rochette described the perforated cast metal bonded design for splinting periodontally compromised teeth. The design was later used for replacing missing teeth. The main causes of failure of the perforated (Rochette) type design were attributed to inappropriate case selection and erosion of the composite from perforations. The aim of this study was to analyse the effect of stress magnitude and direction on failure of perforated resin bonded bridges (RBBs). The objective was to compare stress magnitudes in this design with those reported on the non-perforated RBBs. Photoelastic modelling materials were selected to represent the relative stiffnesses of a posterior mandibular and an anterior maxillary perforated (Rochette) type design. The sizes of the models were scaled to x 2.5 in order to enhance visual analysis of the stress patterns. Stress magnitudes were quantified from isochromatic fringes and stress directions were evaluated from stress trajectories. These revealed a high-stress concentration around the perforations, particularly for those at the proximo-lingual/palatal (connector) areas. This experimental study revealed that the main reason for failure of Rochette designs is deformation at the perforations.

  20. Directional bending wave propagation in periodically perforated plates

    DEFF Research Database (Denmark)

    Andreassen, Erik; Manktelow, Kevin; Ruzzene, Massimo

    2015-01-01

    We report on the investigation of wave propagation in a periodically perforated plate. A unit cell with double-C perforations is selected as a test article suitable to investigate two-dimensional dispersion characteristics, group velocities, and internal resonances. A numerical model, formulated ...

  1. A nonlinear Hermitian transfinite element method for transient behavior analysis of hollow functionally graded cylinders with temperature-dependent materials under thermo-mechanical loads

    Energy Technology Data Exchange (ETDEWEB)

    Shariyat, M. [Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Tehran (Iran, Islamic Republic of)], E-mail: m_shariyat@yahoo.com

    2009-04-15

    In the present paper, an algorithm for nonlinear transient behavior analysis of thick functionally graded cylindrical vessels or pipes with temperature-dependent material properties under thermo-mechanical loads is presented. In contrast to researches presented so far, a Hermitian transfinite element method is proposed to improve the accuracy and to prevent artificial interference or cohesion formation at the mutual boundaries of the elements. Time variations of the temperatures, displacements, and stresses are obtained through a numerical Laplace inversion. Another novelty of the present research is using the transfinite element method to solve nonlinear problems. A sensitivity analysis includes investigating effects of the volume fraction index, dimensions, and temperature-dependency of the material properties is performed. Results confirm the efficiency of the present algorithm and reveal the significant effects of the temperature-dependency of the material properties and the elastic wave reflections and interferences on the responses. In comparison to other techniques, the present technique may be used to obtain relatively accurate and stable results in a less computational time.

  2. Application of a maximum entropy method to estimate the probability density function of nonlinear or chaotic behavior in structural health monitoring data

    Science.gov (United States)

    Livingston, Richard A.; Jin, Shuang

    2005-05-01

    Bridges and other civil structures can exhibit nonlinear and/or chaotic behavior under ambient traffic or wind loadings. The probability density function (pdf) of the observed structural responses thus plays an important role for long-term structural health monitoring, LRFR and fatigue life analysis. However, the actual pdf of such structural response data often has a very complicated shape due to its fractal nature. Various conventional methods to approximate it can often lead to biased estimates. This paper presents recent research progress at the Turner-Fairbank Highway Research Center of the FHWA in applying a novel probabilistic scaling scheme for enhanced maximum entropy evaluation to find the most unbiased pdf. The maximum entropy method is applied with a fractal interpolation formulation based on contraction mappings through an iterated function system (IFS). Based on a fractal dimension determined from the entire response data set by an algorithm involving the information dimension, a characteristic uncertainty parameter, called the probabilistic scaling factor, can be introduced. This allows significantly enhanced maximum entropy evaluation through the added inferences about the fine scale fluctuations in the response data. Case studies using the dynamic response data sets collected from a real world bridge (Commodore Barry Bridge, PA) and from the simulation of a classical nonlinear chaotic system (the Lorenz system) are presented in this paper. The results illustrate the advantages of the probabilistic scaling method over conventional approaches for finding the unbiased pdf especially in the critical tail region that contains the larger structural responses.

  3. Perforated SiN membrane resonators for nanomechanical IR spectroscopy poster

    DEFF Research Database (Denmark)

    Kurek, Maksymilian; Carnoy, Matthias; Boisen, Anja

    behavior. The principle of operation is based on the monitoring of the resonance frequency shift dueto various external factors such as change of temperature. It has been shown that photothermal infrared (IR) spectroscopy based onnanomechanical silicon nitride (SiN) string resonators (NAM-IR) enables...... the exceptionally fast chemical analysis of pictograms of analytedirectly from liquid solution in only a few minutes [1]. However in this technique the coupling of the IR laser beam to the nanometerwidestring resonators is difficult and inefficient. Therefore perforated SiN membranes with thickness of 100 nm......, lateral dimension of1×1 mm2 and 2 µm perforation grid pitch were used instead of strings which makes the IR beam alignment significantly simpler whilemaintaining similar sampling efficiency and photothermal IR absorption sensitivity....

  4. Durability of Bridge Expansion Joints with Perforated Dowels Under Traffic Impact Loading

    Institute of Scientific and Technical Information of China (English)

    YODA Teruhiko; YOSHIDA Tetsuya; SETA Makoto

    2006-01-01

    In design phases,expansion joints are required to have movement capacity,bearing capacity for static and dynamic loading,watertight,low noise emission and traffic safety.On the basis of the fact that failure due to dynamic loading is the main reason for the observed damages,attention is focused on the bearing capacity for dynamic loading governed by impact,because it differs from the static loading.In this study,from the viewpoint of durability,experimental studies for dynamic behavior were conducted for aluminium alloy expansion joints with perforated dowels.The validity of the perforated dowels against traffic impact loading was confirmed by both experimental and numerical studies.

  5. Simulation of nonlinear benchmarks and sheet metal forming processes using linear and quadratic solid–shell elements combined with advanced anisotropic behavior models

    Directory of Open Access Journals (Sweden)

    WangPeng

    2016-01-01

    Full Text Available A family of prismatic and hexahedral solid‒shell (SHB elements with their linear and quadratic versions is presented in this paper to model thin 3D structures. Based on reduced integration and special treatments to eliminate locking effects and to control spurious zero-energy modes, the SHB solid‒shell elements are capable of modeling most thin 3D structural problems with only a single element layer, while describing accurately the various through-thickness phenomena. In this paper, the SHB elements are combined with fully 3D behavior models, including orthotropic elastic behavior for composite materials and anisotropic plastic behavior for metallic materials, which allows describing the strain/stress state in the thickness direction, in contrast to traditional shell elements. All SHB elements are implemented into ABAQUS using both standard/quasi-static and explicit/dynamic solvers. Several benchmark tests have been conducted, in order to first assess the performance of the SHB elements in quasi-static and dynamic analyses. Then, deep drawing of a hemispherical cup is performed to demonstrate the capabilities of the SHB elements in handling various types of nonlinearities (large displacements and rotations, anisotropic plasticity, and contact. Compared to classical ABAQUS solid and shell elements, the results given by the SHB elements show good agreement with the reference solutions.

  6. Steady-state, self-oscillating and chaotic behavior of a PID controlled nonlinear servomechanism by using Bogdanov-Takens and Andronov-Poincaré-Hopf bifurcations

    Science.gov (United States)

    Pérez-Molina, Manuel; Pérez-Polo, Manuel F.

    2014-10-01

    This paper analyzes a controlled servomechanism with feedback and a cubic nonlinearity by means of the Bogdanov-Takens and Andronov-Poincaré-Hopf bifurcations, from which steady-state, self-oscillating and chaotic behaviors will be investigated using the center manifold theorem. The system controller is formed by a Proportional plus Integral plus Derivative action (PID) that allows to stabilize and drive to a prescribed set point a body connected to the shaft of a DC motor. The Bogdanov-Takens bifurcation is analyzed through the second Lyapunov stability method and the harmonic-balance method, whereas the first Lyapunov value is used for the Andronov-Poincaré-Hopf bifurcation. On the basis of the results deduced from the bifurcation analysis, we show a procedure to select the parameters of the PID controller so that an arbitrary steady-state position of the servomechanism can be reached even in presence of noise. We also show how chaotic behavior can be obtained by applying a harmonical external torque to the device in self-oscillating regime. The advantage of achieving chaotic behavior is that it can be used so that the system reaches a set point inside a strange attractor with a small control effort. The analytical calculations have been verified through detailed numerical simulations.

  7. Long-time and large-distance asymptotic behavior of the current-current correlators in the non-linear Schroedinger model

    Energy Technology Data Exchange (ETDEWEB)

    Kozlowski, K.K. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Terras, V. [CNRS, ENS Lyon (France). Lab. de Physique

    2010-12-15

    We present a new method allowing us to derive the long-time and large-distance asymptotic behavior of the correlations functions of quantum integrable models from their exact representations. Starting from the form factor expansion of the correlation functions in finite volume, we explain how to reduce the complexity of the computation in the so-called interacting integrable models to the one appearing in free fermion equivalent models. We apply our method to the time-dependent zero-temperature current-current correlation function in the non-linear Schroedinger model and compute the first few terms in its asymptotic expansion. Our result goes beyond the conformal field theory based predictions: in the time-dependent case, other types of excitations than the ones on the Fermi surface contribute to the leading orders of the asymptotics. (orig.)

  8. Self-similarity and long-time behavior of solutions of the diffusion equation with nonlinear absorption and a boundary source

    CERN Document Server

    Gordon, Peter V

    2012-01-01

    This paper deals with the long-time behavior of solutions of nonlinear reaction-diffusion equations describing formation of morphogen gradients, the concentration fields of molecules acting as spatial regulators of cell differentiation in developing tissues. For the considered class of models, we establish existence of a new type of ultra-singular self-similar solutions. These solutions arise as limits of the solutions of the initial value problem with zero initial data and infinitely strong source at the boundary. We prove existence and uniqueness of such solutions in the suitable weighted energy spaces. Moreover, we prove that the obtained self-similar solutions are the long-time limits of the solutions of the initial value problem with zero initial data and a time-independent boundary source.

  9. Pneumoscrotum: A rare manifestation of perforation associated with therapeutic colonoscopy

    Institute of Scientific and Technical Information of China (English)

    Kuang-I Fu; Takahiro Fujimori; Yasushi Sano; Shigeharu Kato; Takahiro Fujii; Masanori Sugito; Masato Ono; Norio Saito; Kiyotaka Kawashima; Shigeaki Yoshida

    2005-01-01

    Pneumoscrotum is uncommon and also rarely reported as a complication associated with colonic perforation. A case of colonic perforation in delayed fashion associated with EMR, revealed by pneumoscrotum, is reported and the associated literatures are reviewed. A 52-year-old male received piecemeal EMR for a laterally spreading tumor 35 mm in size in our hospital. He complained of enlargement of the scrotum and revisited our hospital the day after the procedure. A diagnosis of pneumoscrotum was made, and as most such cases have been reported to be associated with pneumoperitoneum, colonic perforation was suspected. Free air but no fluid collection was found by abdominal computed tomography, and delayed colonic perforation was diagnosed. However, as there were no clinical signs of peritoneal irritation,conservative treatment was administered and the patient recovered uneventfully. Pneumoscrotum could be a sign of colonic perforation after EMR, and treatment should be carefully chosen.

  10. Esophageal Perforation due to Transesophageal Echocardiogram: New Endoscopic Clip Treatment

    Directory of Open Access Journals (Sweden)

    John Robotis

    2014-07-01

    Full Text Available Esophageal perforation due to transesophageal echocardiogram (TEE during cardiac surgery is rare. A 72-year-old female underwent TEE during an operation for aortic valve replacement. Further, the patient presented hematemesis. Gastroscopy revealed an esophageal bleeding ulcer. Endoscopic therapy was successful. Although a CT scan excluded perforation, the patient became febrile, and a second gastroscopy revealed a big perforation at the site of ulcer. The patient's clinical condition required endoscopic intervention with a new OTSC® clip (Ovesco Endoscopy, Tübingen, Germany. The perforation was successfully sealed. The patient remained on intravenous antibiotics, proton pump inhibitors and parenteral nutrition for few days, followed by enteral feeding. She was discharged fully recovered 3 months later. We clearly demonstrate an effective, less invasive treatment of an esophageal perforation with a new endoscopic clip.

  11. Perforated jejunal diverticulum in the use of mycophenolate mofetil

    Directory of Open Access Journals (Sweden)

    Charat Thongprayoon

    2014-01-01

    Full Text Available Context: Jejunal diverticulosis is a rare disease. Common acute complications include diverticulitis, intestinal obstruction, bleeding and perforation. Gastrointestinal tract perorations have also been rarely observed in the use of mycophenolate mofetil. Case Report: We report a 44-year-old man with end-stage renal disease post failed kidney transplant on low-dose mycophenolate mofetil who presented with acute onset of abdominal pain. He was successfully given the diagnosis of perforated jejunal diverticulum. The patient successfully underwent a segmental jejunal resection and anastomosis. He unfortunately developed a recurrent jejunal perforation a month later and again had the second segmental jejunal resection operation. Mycophenolate mofetil then was discontinued. Conclusion: The present case illustrates jejunal diverticulum perforation in the use of mycophenolate mofetil. Physicians should increase the awareness of this association of perforated jejunal diverticulum in patients using mycophenolate mofetil.

  12. Spontaneous Uterine Perforation due to Pyometra Presenting as Acute Abdomen

    Directory of Open Access Journals (Sweden)

    Loabat Geranpayeh

    2006-01-01

    Full Text Available Spontaneous perforation of the uterus is rare, its incidence being about 0.01%–0.05%. We report a rare case of diffuse peritonitis caused by spontaneously perforated pyometra. A 63-year-old woman with severe abdominal pain was admitted to our hospital. Laparotomy was performed because of the suspicion of gastrointestinal perforation with generalized peritonitis. At laparotomy, about 900 mL of pus was found in the peritoneal cavity. There were no abnormal findings in the alimentary tract, liver, or gallbladder. A total abdominal hysterectomy with bilateral salpingo-oophorectomy was performed. Pathological investigation of the surgical specimen revealed endometritis and myometritis of the uterus; but there was no evidence of malignancy, and the cervical canal was patent. Although spontaneously perforated pyometra is rare, a perforated pyometra should therefore also be considered when elderly women present with acute abdominal pain.

  13. CFD Simulations of Oscillating Flow around Solid and Perforated Plates

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Damping plates have been used for truss spars in gulf of Mexico to reduce the heave motions. The plates are usually perforated with holes for the passage of marine risers, but the effects of the perforation have not been examined thoroughly. In the present study, a computational fluid dynamics investigation into the hydrodynamic forces is carried out by using FLUENT, which is on two-dimensional perforated plates with varying degrees of perforation in oscillating flow under small Keulegan-Carpenter (KC) number. The numerical results of the hydrodynamic coefficients are presented. The effects of both the perforation ratio (PR) and KC number on the hydrodynamic coefficients of the plates are discussed. Some results of the simulated flow patterns around the plates were also given and discussed.

  14. Features of Flow Past Square Cylinder with a Perforated Plate

    Institute of Scientific and Technical Information of China (English)

    汪健生; 徐亚坤; 程浩杰

    2016-01-01

    A numerical investigation was performed on the reduction of the fluid forces acting on the square cylin-der in the laminar flow regime with a perforated plate. The effects of geometric parameters such as the distance between the square cylinder and the perforated plate on the wake of the square cylinder were discussed. Further-more, the flow characteristics such as the drag coefficient, lift coefficient, Strouhal number and flow pattern were obtained. It can be concluded that the drag force of the square cylinder reduces to some extent due to the addition of the perforated plate. The flow structure varies when the perforated plate is located behind the square cylinder. Moreover, the recirculation zone augments with the increase ofL/D, and the vortex trace on the upper and lower surface of the square cylinder moves gradually backwards until a stable recirculation zone formed between the square cylinder and the perforated plate.

  15. Effect of CFRP Schemes on the Flexural Behavior of RC Beams Modeled by Using a Nonlinear Finite-element Analysis

    Science.gov (United States)

    Al-Rousan, R. Z.

    2015-09-01

    The main objective of this study was to assess the effect of the number and schemes of carbon-fiber-reinforced polymer (CFRP) sheets on the capacity of bending moment, the ultimate displacement, the ultimate tensile strain of CFRP, the yielding moment, concrete compression strain, and the energy absorption of RC beams and to provide useful relationships that can be effectively utilized to determine the required number of CFRP sheets for a necessary increase in the flexural strength of the beams without a major loss in their ductility. To accomplish this, various RC beams, identical in their geometric and reinforcement details and having different number and configurations of CFRP sheets, are modeled and analyzed using the ANSYS software and a nonlinear finite-element analysis.

  16. Dynamical behaviors of the shock compacton in the nonlinearly Schrödinger equation with a source term

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Jiuli, E-mail: yjl@ujs.edu.cn; Zhao, Liuwei

    2014-11-07

    In this paper, the dynamics from the shock compacton to chaos in the nonlinearly Schrödinger equation with a source term is investigated in detail. The existence of unclosed homoclinic orbits which are not connected with the saddle point indicates that the system has a discontinuous fiber solution which is a shock compacton. We prove that the shock compacton is a weak solution. The Melnikov technique is used to detect the conditions for the occurrence from the shock compacton to chaos and further analysis of the conditions for chaos suppression. The results show that the system turns to chaos easily under external disturbances. The critical parameter values for chaos appearing are obtained analytically and numerically using the Lyapunov exponents and the bifurcation diagrams.

  17. Unexpected Behavior on Nonlinear Tunneling of Chirped Ultrashort Soliton Pulse in Non-Kerr Media with Raman Effect

    Science.gov (United States)

    Rajan, M. S. Mani

    2016-08-01

    In this manuscript, the ultrashort soliton pulse propagation through nonlinear tunneling in cubic quintic media is investigated. The effect of chirping on propagation characteristics of the soliton pulse is analytically investigated using similarity transformation. In particular, we investigate the propagation dynamics of ultrashort soliton pulse through dispersion barrier for both chirp and chirp-free soliton. By investigating the obtained soliton solution, we found that chirping has strong influence on soliton dynamics such as pulse compression with amplification. These two important dynamics of chirped soliton in cubic quintic media open new possibilities to improve the solitonic communication system. Moreover, we surprisingly observe that a dispersion well is formed for the chirped case whereas a barrier is formed for the chirp-free case, which has certain applications in the construction of logic gate devices to achieve ultrafast switching.

  18. Nonlinear Peltier effect in semiconductors

    Science.gov (United States)

    Zebarjadi, Mona; Esfarjani, Keivan; Shakouri, Ali

    2007-09-01

    Nonlinear Peltier coefficient of a doped InGaAs semiconductor is calculated numerically using the Monte Carlo technique. The Peltier coefficient is also obtained analytically for single parabolic band semiconductors assuming a shifted Fermi-Dirac electronic distribution under an applied bias. Analytical results are in agreement with numerical simulations. Key material parameters affecting the nonlinear behavior are doping concentration, effective mass, and electron-phonon coupling. Current density thresholds at which nonlinear behavior is observable are extracted from numerical data. It is shown that the nonlinear Peltier effect can be used to enhance cooling of thin film microrefrigerator devices especially at low temperatures.

  19. NON-LINEAR ANALYSIS OF EFFECT OF CONFINEMENT REGIONS ON MOMENT CURVATURE BEHAVIOR OF SHEAR WALL (THEORETICAL STUDY

    Directory of Open Access Journals (Sweden)

    Şevket Murat ŞENEL

    2002-02-01

    Full Text Available Computer program which investigates the effectiveness of confinement regions of shear walls was developed.Specimens which have unique web reinforcement and different confinement regions were analyzed by using this computer program. Data needed for theoratical computations were obtained by tensile testing of steel rods and by concrete specimen tests. Mander Method was applied to reflect confined concrete behavior. Strain hardening behavior of steel was included in computations. Effect of stirrup spacing and hook reinforcement was introduced together and seperately to understand the moment-curvature response of specimens.

  20. Nonlinear dynamics of structures

    CERN Document Server

    Oller, Sergio

    2014-01-01

    This book lays the foundation of knowledge that will allow a better understanding of nonlinear phenomena that occur in structural dynamics.   This work is intended for graduate engineering students who want to expand their knowledge on the dynamic behavior of structures, specifically in the nonlinear field, by presenting the basis of dynamic balance in non‐linear behavior structures due to the material and kinematics mechanical effects.   Particularly, this publication shows the solution of the equation of dynamic equilibrium for structure with nonlinear time‐independent materials (plasticity, damage and frequencies evolution), as well as those time dependent non‐linear behavior materials (viscoelasticity and viscoplasticity). The convergence conditions for the non‐linear dynamic structure solution  are studied, and the theoretical concepts and its programming algorithms are presented.  

  1. A Study of the Behavior and Micromechanical Modelling of Granular Soil. Volume 3. A Numerical Investigation of the Behavior of Granular Media Using Nonlinear Discrete Element Simulation

    Science.gov (United States)

    1991-05-22

    Eisenberg 1987). Among other formulations, the existing models are based on the theories of elasticity, hypoelasticity , plasticity and viscoplasticity...AD-A238 158 AFOSR4R. 91 069.1 A STUDY OF THE BEHAVIOR AND MICROMECHANICAL MODELLING OF GRANULAR SOIL DTIC VOLUME mI ELECTIE A NUMERICAL INVESTIGATION...Final 1/6/ 9-5/15/91 4. nU AN SUS"Ll5. FUNDING NUMBERS A Study of the Behavior and Micromechanical Modelling of Grant AFOSR-89-0350 Granular Soil PR

  2. Inverse relationship of the anterolateral and anteromedial thigh flap perforator anatomy.

    Science.gov (United States)

    Yu, Peirong

    2014-09-01

    When anterolateral thigh (ALT) perforators are inadequate, exploration of the contralateral thigh or a new flap may be required. If the anteromedial thigh (AMT) perforators were useable in these instances, harvest could proceed from a single donor site. The purposes of this study were to define the AMT perforator anatomy and examine the relationships between the AMT and ALT perforators. A total of 100 consecutive thighs were explored. The ALT and AMT perforator size and number were documented. The relationship between ALT and AMT size and number was examined using Fisher exact test, logistic regression, and linear regression. The main blood supply to the AMT flap was the rectus femoris branch (RFB) off the descending branch of the lateral circumflex femoris artery. AMT perforators were only present in 51% of the thighs and most likely a single perforator near the midpoint and 3.2 cm medial to the line connecting the anterior superior iliac spine and the patella (perforator B location). Patients with one or fewer ALT perforators had fourfold increased chance of an AMT perforator. Patients with small or no ALT perforators usually had a large AMT perforator. After assigning numeric values to perforators based on size, lower ALT perforator scores were significantly related to higher AMT scores. The RFB is the main vascular pedicle of the AMT flap. There is an inverse relationship between size and number of ALT and AMT perforators: when ALT perforators are inadequate, AMT perforators are typically useable. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  3. Nonlinear rheological models for structured interfaces

    NARCIS (Netherlands)

    Sagis, L.M.C.

    2010-01-01

    The GENERIC formalism is a formulation of nonequilibrium thermodynamics ideally suited to develop nonlinear constitutive equations for the stress–deformation behavior of complex interfaces. Here we develop a GENERIC model for multiphase systems with interfaces displaying nonlinear viscoelastic stres

  4. Detection of Perforators Using Smartphone Thermal Imaging.

    Science.gov (United States)

    Hardwicke, Joseph T; Osmani, Omer; Skillman, Joanna M

    2016-01-01

    Thermal imaging detects infrared radiation from an object, producing a thermogram that can be interpreted as a surrogate marker for cutaneous blood flow. To date, high-resolution cameras typically cost tens of thousands of dollars. The FLIR ONE is a smartphone-compatible miniature thermal imaging camera that currently retails at under $200. In a proof-of-concept study, patients and healthy volunteers were assessed with thermal imaging for (1) detecting and mapping perforators, (2) defining perforasomes, and (3) monitoring free flaps. Preoperative, intraoperative, and postoperative thermograms can assist in the planning, execution, and monitoring of free flaps, and the FLIR ONE provides a low-cost adjunct that could be applied to other areas of burns and plastic surgery.

  5. Intrathoracic Caecal Perforation Presenting as Dyspnea

    Directory of Open Access Journals (Sweden)

    Vincent Granier

    2010-01-01

    Full Text Available Introduction. Bochdalek hernia is a congenital defect of the diaphragm that is usually diagnosed in the neonatal period and incidentally in asymptomatic adults. Small bowel incarceration in a right-sided Bochdalek hernia is exceptional for an adult. Case Presentation. A 54-year-old woman was admitted for acute dyspnea, tachycardia, hypotension, and fever. Five days before, she had been experiencing an episode of diffuse abdominal pain. The admission chest X-ray was interpreted as right pleural effusion and pneumothorax with left mediastinal shift. Chest tube drainage was purulent. The thoracoabdominal CT examination suspected an intestinal incarceration through a right diaphragmatic defect. At laparotomy, a right-sided Bochdalek hernia was confirmed with a complete necrosis of the incarcerated caecum. Ileocaecal resection was performed, but the patient died from delayed septic complications. Conclusion. Intrathoracic perforation of the caecum is a rare occurrence; delayed diagnosis due to misleading initial symptoms may lead to severe complications and poor prognosis.

  6. Medical image of the week: tracheal perforation

    Directory of Open Access Journals (Sweden)

    Parsa N

    2014-12-01

    Full Text Available A 45 year old Caucasian man with a history of HIV/AIDS was admitted for septic shock secondary to right lower lobe community acquired pneumonia. The patient’s respiratory status continued to decline requiring emergency intubation in a non-ICU setting. Four laryngoscope intubation attempts were made including an inadvertent esophageal intubation. Subsequent CT imaging revealed a tracheal defect (Figure 1, red arrow with communication to the mediastinum and air around the trachea consistent with pneumomediastinum (Figure 2, orange arrow and figure 3, yellow arrow. Pneumopericardium (figure 4, blue arrow was also evident post-intubation. The patient’s hemodynamic status remained stable. Two days following respiratory intubation subsequent chest imaging revealed resolution of the pneumomediastinum and pneumopericardium and patient continued to do well without hemodynamic compromise or presence of subcutaneous emphysema. Post-intubation tracheal perforation is a rare complication of traumatic intubation and may be managed with surgical intervention or conservative treatment (1.

  7. Spontaneous Perforation of Pyometra: A Case Report

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available Pyometra is the accumulation of purulent material in the uterine cavity. Its reported incidence is 0.01–0.5% in gynecologic patients; however, as far as elderly patients are concerned, its incidence is 13.6% [3]. The most common cause of pyometra is malignant diseases of genital tract and the consequences of their treatment (radiotherapy. Other causes are benign tumors like leiomyoma, endometrial polyps, senile cervicitis, cervical occlusion after surgery, puerperal infections, and congenital cervical anomalies. Spontaneous rupture of the uterus is an extremely rare complication of pyometra. To our knowledge, only 21 cases of spontaneous perforation of pyometra have been reported in English literature since 1980. This paper reports an additional case of spontaneous uterine rupture.

  8. Intrathoracic caecal perforation presenting as dyspnea.

    Science.gov (United States)

    Granier, Vincent; Coche, Emmanuel; Hantson, Philippe; Thoma, Maximilien

    2010-01-01

    Introduction. Bochdalek hernia is a congenital defect of the diaphragm that is usually diagnosed in the neonatal period and incidentally in asymptomatic adults. Small bowel incarceration in a right-sided Bochdalek hernia is exceptional for an adult. Case Presentation. A 54-year-old woman was admitted for acute dyspnea, tachycardia, hypotension, and fever. Five days before, she had been experiencing an episode of diffuse abdominal pain. The admission chest X-ray was interpreted as right pleural effusion and pneumothorax with left mediastinal shift. Chest tube drainage was purulent. The thoracoabdominal CT examination suspected an intestinal incarceration through a right diaphragmatic defect. At laparotomy, a right-sided Bochdalek hernia was confirmed with a complete necrosis of the incarcerated caecum. Ileocaecal resection was performed, but the patient died from delayed septic complications. Conclusion. Intrathoracic perforation of the caecum is a rare occurrence; delayed diagnosis due to misleading initial symptoms may lead to severe complications and poor prognosis.

  9. Preliminary Clinical Study on Perforating Prosthokeratoplasty

    Institute of Scientific and Technical Information of China (English)

    Jian Chen; Jintang Xu; SA Yakimenko; Guanghui Hou; Bingji Sun; Aning Zheng; Songbin Zhao

    2003-01-01

    Purpose: To observe the effects of perforating prosthokeratoplasty on patients with leucoma who failed in keratoplasty or were not suitable for keratoplasty, and improved their vision.Methods:Five cases with leucoma (4 with chemical burn and 1 with blast) received Yakimenko Style keratoprosthesis implantation. Preoperative examination showed the visual acuity in 4 of the 5 cases was light perception, and that of the other one was FC/20 crm.The light orientation in 3 patients was definite, and that in the other two was indefinite.Results: The vision improved in 4 of 5 patients in the follow-up period of 9 months to 3 years. Their visual acuity showed 0.09 to 0.8. And there was no change of vision in the other 1 case.Conclutions :Prosthokeratoplasty is the first choice for rehabilitation of the blind that have leucoma but are not suitable for or failed in penetrating keratoplasty.

  10. Visible Perforating Lateral Osteotomy: Internal Perforating Technique with Wide Periosteal Dissection

    Directory of Open Access Journals (Sweden)

    Bong Il Rho

    2016-01-01

    Full Text Available There are two general categories of lateral osteotomy techniques—the external perforating method and the internal continuous method. Regardless of which technique is used, procedural effectiveness is hampered by limited visualization in the surgical field. Considering this point, we devised a new technique that involves using a wide subperiosteal dissection and internal perforation under direct visualization. Using an intranasal approach, whereby the visibility of the intended fracture line was maintained, enabled a greater degree of control, and in turn, results that were more precise, and thus predictable and reproducible. Traditionally, it has been taken as dogma that the periosteum must be preserved, considering the potential for dead space and bony instability; however, under sufficient visualization of the surgical field with an internal perforating method, complete osteotomy with fully preserved intranasal mucosa could be conducted exactly as intended. This intact mucosal lining compensates for the elevated periosteum. Compressive dressing and drainage through a Silastic angio-needle catheter enabled the elimination of dead space. Therefore, precise, reproducible, and predictable osteotomy minimizing the potential for associated complications such as ecchymosis, that is, bruising owing to hemorrhage, could be performed. In this article, we introduce a novel technique for lateral osteotomy with improved visualization.

  11. Asymptotic Behavior of Global Solution for Nonlinear Generalized Euler-Possion-Darboux Equation%一类非线性广义Euler-Poisson-Darboux方程整体解的渐近性质

    Institute of Scientific and Technical Information of China (English)

    梁保松; 陈振

    2004-01-01

    J. L Lions and W. A. Stranss [1] have proved the existence of a global solution of the initial boundary value problem for nonlinear generalized Euler-Possion-Darboux equation. In this paper we are going to investigate the asymptotic behavior of the global solution by a difference inequality.

  12. Aeroelastic Modeling and Behavior of Lifting Surfaces Incorporating Aerodynamic and Structural Nonlinearities: Volterra Series and Indicial Function Approach

    Science.gov (United States)

    Librescu, Liviu

    2001-01-01

    Within this NASA Grant, the following points should be emphasized: 1) All the objectives stated in the proposal of the grant have been accomplished. Moreover. the activity within the project has addressed additional issues, of the linear and nonlinear aeroelasticity, not included in the objectives of the grant. 2) During the activities within the grant, we have been in a permanent contact with Dr. Walter A. Silva, the monitor of the NASA Project, to whom we have reported continuously our achievements. 3) As a result of the activities within the grant a number of papers: a. have been submitted for publication to the AIAA Journals, namely the AIAA Journal and the Journal of Guidance, Control, and Dynamics, and b. have been presented at the specialized National Conferences and an International Congress, and have appeared in the proceedings of these Conferences. 4) A list of papers submitted for publication and presented at Conferences is appended herewith. 5) In all these papers, an acknowledgment to NASA Langley Research Center was included.

  13. Laser-mediated perforation of plant cells

    Science.gov (United States)

    Wehner, Martin; Jacobs, Philipp; Esser, Dominik; Schinkel, Helga; Schillberg, Stefan

    2007-07-01

    The functional analysis of plant cells at the cellular and subcellular levels requires novel technologies for the directed manipulation of individual cells. Lasers are increasingly exploited for the manipulation of plant cells, enabling the study of biological processes on a subcellular scale including transformation to generate genetically modified plants. In our setup either a picosecond laser operating at 1064 nm wavelength or a continuous wave laser diode emitting at 405 nm are coupled into an inverse microscope. The beams are focused to a spot size of about 1.5 μm and the tobacco cell protoplasts are irradiated. Optoporation is achieved when targeting the laser focal spot at the outermost edge of the plasma membrane. In case of the picosecond laser a single pulse with energy of about 0.4 μJ was sufficient to perforate the plasma membrane enabling the uptake of dye or DNA from the surrounding medium into the cytosol. When the ultraviolet laser diode at a power level of 17 mW is employed an irradiation time of 200 - 500 milliseconds is necessary to enable the uptake of macromolecules. In the presence of an EYFP encoding plasmid with a C-terminal peroxisomal signal sequence in the surrounding medium transient transformation of tobacco protoplasts could be achieved in up to 2% of the optoporated cells. Single cell perforation using this novel optoporation method shows that isolated plant cells can be permeabilized without direct manipulation. This is a valuable procedure for cell-specific applications, particularly where the import of specific molecules into plant cells is required for functional analysis.

  14. Influence of operating microscope in the sealing of cervical perforations

    Directory of Open Access Journals (Sweden)

    Bruna Schwingel Schmidt

    2016-01-01

    Full Text Available Context: Accidental root canal perforations are among the main complications of endodontic treatment. Aim: This study evaluated the influence of operating microscope (OM in the marginal adaptation of mineral trioxide aggregate (MTA (Angelus® and glass ionomer (Vitremer inserted into cervical perforations. Materials and Methods: Perforations were made in the cervical third of the buccal wall of the root canal in mandibular incisors. Next, the teeth were divided into four groups (N = 10: MG - MTA without OM; VG - Vitremer without OM; MOMG - MTA with OM; VOMG - Vitremer with OM. The perforations were sealed according to the group and the teeth were prepared for analysis by confocal laser scanning microscope. Images of perforation region (1,024Χ were made and the gap presented by the materials was measured using the Image J program. LEXT OLS4100 three dimensional (3D measuring laser microscope measured the volumetric misfit. Data of gap were analyzed by Kruskal-Wallis and Dunn′s tests. Analysis of variance (ANOVA and Tukey′s tests compared the volumetric misfits. Results: The results showed lower volume and gap in the interface dentin/material in VOMG compared to the other groups (P < 0.05. Conclusion: The use of OM improved the quality of cervical perforations sealed with Vitremer, being indicated in clinical situations of iatrogenic cervical perforations.

  15. [Non-surgical treatment of perforations of the thoracic esophagus].

    Science.gov (United States)

    Slim, K; Elbaz, V; Pezet, D; Chipponi, J

    1996-02-03

    Thoracic oesophageal perforations are life-threatening conditions requiring immediate treatment. The type of treatment remains however controversial. The aim of this study was to evaluate the efficacy of the nonoperative management in this disease. Six patients were admitted in our surgical unit for thoracic oesophageal perforations during the study period. One perforation was spontaneous (Boerhaave's syndrome). One had complicated an oesophageal ulcer. Two were secondary to caustic lesions. Two were secondary to instrumental dilations. The diagnostic and therapeutic delay was suction, and total parenteral nutrition. There was no death in this group of patients. The mediastinitis healed in all cases. In the follow-up period two patients did not have nutritional restriction after healing. Three patients complained of oesophageal stenosis which required oesophageal replacement (n = 2) and dilation (n = 1). One neoplastic stenosis required an endoprosthesis. Nonoperative treatment is feasible and safe in selected cases of thoracic oesophageal perforations: perforations diagnosed early and confined to the mediastinum, instrumental perforations, and perforations diagnosed late but well tolerated.

  16. Risk of surgical glove perforation in oral and maxillofacial surgery.

    Science.gov (United States)

    Kuroyanagi, N; Nagao, T; Sakuma, H; Miyachi, H; Ochiai, S; Kimura, Y; Fukano, H; Shimozato, K

    2012-08-01

    Oral and maxillofacial surgery, which involves several sharp instruments and fixation materials, is consistently at a high risk for cross-contamination due to perforated gloves, but it is unclear how often such perforations occur. This study aimed to address this issue. The frequency of the perforation of surgical gloves (n=1436) in 150 oral and maxillofacial surgeries including orthognathic surgery (n=45) was assessed by the hydroinsufflation technique. Orthognathic surgery had the highest perforation rate in at least 1 glove in 1 operation (91.1%), followed by cleft lip and palate surgery (55.0%), excision of oral soft tumour (54.5%) and dental implantation (50.0%). The perforation rate in scrub nurses was 63.4%, followed by 44.4% in surgeons and first assistants, and 16.3% in second assistants. The odds ratio for the perforation rate in orthognathic surgery versus other surgeries was 16.0 (95% confidence interval: 5.3-48.0). The protection rate offered by double gloving in orthognathic surgery was 95.2%. These results suggest that, regardless of the surgical duration and blood loss in all fields of surgery, orthognathic surgery must be categorized in the highest risk group for glove perforation, following gynaecological and open lung surgery, due to the involvement of sharp objects.

  17. Modified lumbar artery perforator flaps for gluteal pressure sore reconstruction.

    Science.gov (United States)

    Yoon, Chi Sun; Yim, Ji Hong; Kim, Min Ho; Ha, Won; Kim, Kyu Nam

    2016-03-21

    Gluteal perforator flaps (GPFs) are the most useful for gluteal region pressure sore reconstruction. However, application is difficult if the surrounding area has scar tissue from previous operations or trauma, especially with recurrent sores. We describe the use of modified lumbar artery perforator flaps when GPFs cannot be used. Between May 2009 and April 2014, 51 patients underwent gluteal pressure sore reconstructions with gluteal (n = 39) or modified lumbar artery (n = 12) perforator flaps. Patients in the modified lumbar artery perforator group had scar tissue from trauma or previous surgery. In this retrospective review, we analyzed patient age and sex, defect size and location, operative time, follow-up duration, immediate postoperative issues, flap necrosis, dehiscence, re-operation, donor-site morbidity and recurrence. Complications and clinical outcomes were compared between groups. We found no significant differences in patient demographics, surgical complications or clinical outcomes. There were eight cases of temporary congestion (20.51%) and four of partial flap necrosis (10.25%) in the gluteal perforator group. In the modified lumbar artery perforator group, there were three cases of temporary congestion (25%) and one of partial flap necrosis (8.33%). No pressure sores recurred during follow-up in either group. GPFs are the gold standards for gluteal pressure sores, but modified lumbar artery perforator flaps are relatively easy and useful when GPFs cannot be used due to scar tissue. © 2016 Royal Australasian College of Surgeons.

  18. Relationship between anelastic and non-linear visco-plastic behavior of 316 stainless steel at low homologous temperature

    Energy Technology Data Exchange (ETDEWEB)

    Nir, N.; Huang, F.H.; Hart, E.W.; Li, C.Y.

    1976-05-01

    At low homologous temperature the plastic strain rate seems to be controlled largely by dislocation glide friction. However, since a sizeable fraction of the applied stress sigma is dissipated in overcoming the strong barriers due to dislocation tangles generated by strain hardening, only a portion of the applied stress is actually expended against the frictional resistance. A recent model for this process includes the role of dislocation pile-ups at the strong barriers. The pile-ups provide a mechanism for producing the internal back stresses that limit the effective frictional stress. The also appear in the deformation as a stored anelastic strain component. The resultant behavior at low temperature and high stress is similar to that proposed by Grupta and Li. The same model also predicts an anelastic behavior at low stress. Measurements at both high and low stress levels on 316 Stainless Steel have now shown that the predictions of the model are quantitatively consistent at both stress levels.

  19. Nonlinear Dynamical Behavior in BS Evolution Model Based on Small-World Network Added with Mechanism of Preferential Connection

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this paper, we introduce a modified small-world network added with new links with preferential connection instead of adding randomly, then we apply Bak-Sneppen (BS) evolution model on this network. Several dynamical character of the model such as the evolution graph, fo avalanche, the critical exponent D and τ, and the distribution of mutation times of all the nodes, show particular behaviors different from those of the model based on the regular network and the small-world network.

  20. Study of a Steel’s Energy Absorption System for Heavy Quadricycles and Nonlinear Explicit Dynamic Analysis of its Behavior under Impact by FEM

    Directory of Open Access Journals (Sweden)

    José Ángel López Campos

    2015-10-01

    Full Text Available Current knowledge of the behavior of heavy quadricycles under impact is still very poor. One of the most significant causes is the lack of energy absorption in the vehicle frame or its steel chassis structure. For this reason, special steels (with yield stresses equal to or greater than 350 MPa are commonly used in the automotive industry due to their great strain hardening properties along the plastic zone, which allows good energy absorption under impact. This paper presents a proposal for a steel quadricycle energy absorption system which meets the percentages of energy absorption for conventional vehicles systems. This proposal is validated by explicit dynamics simulation, which will define the whole problem mathematically and verify behavior under impact at speeds of 40 km/h and 56 km/h using the finite element method (FEM. One of the main consequences of this study is that this FEM–based methodology can tackle high nonlinear problems like this one with success, avoiding the need to carry out experimental tests, with consequent economical savings since experimental tests are very expensive. Finally, the conclusions from this innovative research work are given.

  1. Sound attenuation analysis of water-filled perforated pipe silencers using three-dimensional time-domain computational fluid dynamics approach

    Directory of Open Access Journals (Sweden)

    Xu Zhou

    2016-04-01

    Full Text Available The three-dimensional time-domain computational fluid dynamics approach is employed to calculate and analyze the sound attenuation behavior of water-filled perforated pipe silencers. Transmission loss predictions from the time-domain computational fluid dynamics approach and the frequency-domain finite element method agree well with each other for the straight-through and cross-flow perforated pipe silencers without flow. Then, the time-domain computational fluid dynamics approach is used to investigate the effects of flow velocity, diameter, and porosity of orifices on the sound attenuation behavior of the silencers. The numerical predictions demonstrate that the flow increases the transmission loss, especially at high frequencies. Based on the above analysis, partially plugged straight-through perforated pipe silencer is proposed to improve the sound attenuation performance by increasing the flow velocity through the orifices. In order to eliminate the pass frequency of the perforated pipe silencers and improve the sound attenuation performance in mid- to high-frequency range, a folded straight-through perforated pipe silencer is designed and its sound attenuation behavior is analyzed numerically using the time-domain computational fluid dynamics approach.

  2. Nonlinear optics

    CERN Document Server

    Bloembergen, Nicolaas

    1996-01-01

    Nicolaas Bloembergen, recipient of the Nobel Prize for Physics (1981), wrote Nonlinear Optics in 1964, when the field of nonlinear optics was only three years old. The available literature has since grown by at least three orders of magnitude.The vitality of Nonlinear Optics is evident from the still-growing number of scientists and engineers engaged in the study of new nonlinear phenomena and in the development of new nonlinear devices in the field of opto-electronics. This monograph should be helpful in providing a historical introduction and a general background of basic ideas both for expe

  3. Central perforation of atretic pulmonary valve using coronary microcatheter

    Directory of Open Access Journals (Sweden)

    Saurabh Kumar Gupta

    2017-01-01

    Full Text Available Percutaneous perforation of pulmonary valve, using 0.014” guidewires meant for coronary artery chronic total occlusion (CTO, is increasingly being performed for select cases of pulmonary atresia with intact ventricular septum (PA-IVS. Despite growing experience, procedural failures and complications are not uncommon. Even in infants treated successfully, the orifice created in the atretic pulmonary valve is eccentric. In this report, we present usefulness of coronary microcatheter in alignment of perforating coronary guidewire to the center of atretic pulmonary valve resulting in central perforation.

  4. Esophageal Perforation with Unilateral Fluidothorax Caused by Nasogastric Tube

    Directory of Open Access Journals (Sweden)

    Lukas P. Mileder

    2016-01-01

    Full Text Available Preterm infants are highly susceptible to injuries following necessary and often life-saving medical interventions. Esophageal perforation is a rare, yet serious complication that can be caused by aerodigestive tract suction, endotracheal intubation, or nasogastric tube placement. We present the case of a neonate born at 23 weeks plus three days of gestation with chest radiography showing malposition of the nasogastric feeding tube and massive right-sided effusion of Iopamidol in the pleural cavity due to esophageal perforation. In addition, the article summarizes common signs and symptoms associated with esophageal perforation in infants and discusses diagnostic approaches.

  5. Biliary peritonitis due to gall bladder perforation after percutaneous nephrolithotomy.

    Science.gov (United States)

    Ranjan, Nikhil; Singh, Rana Pratap; Tiwary, Rajesh

    2015-01-01

    A 19-year-old male patient underwent right percutaneous nephrolithotomy (PNL) for right renal 1.5 × 1.5 cm lower pole stone. The procedure was completed uneventfully with complete stone clearance. The patient developed peritonitis and shock 48 h after the procedure. Exploratory laparotomy revealed a large amount of bile in the abdomen along with three small perforations in the gall bladder (GB) and one perforation in the caudate lobe of the liver. Retrograde cholecystectomy was performed but the patient did not recover and expired post-operatively. This case exemplifies the high mortality of GB perforation after PNL and the lack of early clinical signs.

  6. Biliary peritonitis due to gall bladder perforation after percutaneous nephrolithotomy

    Directory of Open Access Journals (Sweden)

    Nikhil Ranjan

    2015-01-01

    Full Text Available A 19-year-old male patient underwent right percutaneous nephrolithotomy (PNL for right renal 1.5 × 1.5 cm lower pole stone. The procedure was completed uneventfully with complete stone clearance. The patient developed peritonitis and shock 48 h after the procedure. Exploratory laparotomy revealed a large amount of bile in the abdomen along with three small perforations in the gall bladder (GB and one perforation in the caudate lobe of the liver. Retrograde cholecystectomy was performed but the patient did not recover and expired post-operatively. This case exemplifies the high mortality of GB perforation after PNL and the lack of early clinical signs.

  7. An unusual case of root perforation caused by surgical trephination.

    Science.gov (United States)

    Kosti, E; Molyvdas, I; Lambrianidis, T

    2008-06-01

    To present the diagnosis and management of an unusual case of root perforation caused by surgical trephination. A root perforation caused by surgical trephination on a maxillary lateral incisor with diagnosis of symptomatic chronic periradicular periodontitis was managed with standard root canal preparation and filling with thermoplasticized gutta-percha. Recall radiographs up to 1 year revealed healing of the periapical lesion. *During surgical trephination, there is risk of damaging anatomical structures surrounding the tooth as well as the tooth itself. *Root perforation caused by trephination was successfully managed by standard canal preparation and filling with thermoplasticized gutta-percha.

  8. A Rare Acute Abdomen Reason: Perforated Jejunal Diverticulitis

    Directory of Open Access Journals (Sweden)

    Oktay Karakose

    2014-06-01

    Full Text Available Jejunal diverticulosis is a rare case that is diagnosed incidental. Although it is generally asymptomatic, it can cause non-spesific symptoms like stomachache, nausea, diarrhoea, malabsorption, bleeding, obstruction and / or perforation. Perforated jejunal diverticulitis is a very rare acute abdomen cause. The acute complications of jejunal diverticulosis can be cause of significant morbidity and mortality especially in old patients. In this text, we report a 81 year old woman case that was operated emergently because of perforated jejunal diverticulitis and was lost in postoperation term because of multiple organ failure.

  9. Successful management of late right ventricular perforation after pacemaker implantation

    Directory of Open Access Journals (Sweden)

    Amir K Bigdeli

    2010-01-01

    Full Text Available Amir K Bigdeli1, Andres Beiras-Fernandez1, Ingo Kaczmarek1, Christian Kowalski2, Michael Schmoeckel1, Bruno Reichart11Department of Cardiac Surgery, 2Department of Anesthesiology, Ludwig-Maximilians University, Munich, GermanyAbstract: Complications of pacemaker implantation include myocardial perforation, venous thrombosis, vegetations of the tricuspid valve or pacing lead, and tricuspid regurgitation. We report a patient presenting with a case of delayed ventricular lead perforation through the right ventricle. The lead was uneventfully extracted under transesophageal echocardiographic observation in the operating room with cardiac surgery backup.Keywords: pacemaker, lead perforation, complication

  10. Pre-expanded Intercostal Perforator Super-Thin Skin Flap.

    Science.gov (United States)

    Liao, Yunjun; Luo, Yong; Lu, Feng; Hyakusoku, Hiko; Gao, Jianhua; Jiang, Ping

    2017-01-01

    This article introduces pre-expanded super-thin intercostal perforator flaps, particularly the flap that has a perforator from the first to second intercostal spaces. The key techniques, advantages and disadvantages, and complications and management of this flap are described. At present, the thinnest possible flap is achieved by thinning the pre-expanded flap that has a perforator from the first to second intercostal spaces. It is used to reconstruct large defects on the face and neck, thus restoring function and cosmetic appearance. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Gastric Perforation Associated with Tuberculosis: A Case Report

    Directory of Open Access Journals (Sweden)

    Richdeep S. Gill

    2011-01-01

    Full Text Available Gastric tuberculosis is a rare presentation of tuberculosis infection. Gastric perforation associated with tuberculosis is exceedingly rare with five previously published cases. We present a case of a male patient that developed presumed gastric tuberculosis secondary to pulmonary tuberculosis infection. He subsequently developed gastric perforation and sepsis, for which he was treated both surgically and medically. Despite ongoing antituberculosis treatment, the patient's condition worsened and the patient died secondary to multiorgan failure. This case highlights gastric perforation as a rare but devastating complication of pulmonary tuberculosis.

  12. Sen perforation af tyndtarm efter laparoskopisk gastrisk bypass

    DEFF Research Database (Denmark)

    Spanager, Lene; Sigild, Ulf Henrik; Neuenschwander, Anders Ulrich

    2010-01-01

    We present two cases in which the patients were admitted to a local hospital with acute abdominal pain four or five months after having undergone laparoscopic gastric bypass. In both cases, operation revealed a perforation of the small bowel close to the distal anastomosis. In the first case......, a massive constipation of the small bowel was most likely a contributing factor. In the second case, the cause was a kink of the entero-entero anastomosis leading to obstruction and finally perforation of the biliary limp. Late perforations are among the rarely reported complications associated with gastric...

  13. Significance of rotating ground motions on nonlinear behavior of symmetric and asymmetric buildings in near fault sites

    Science.gov (United States)

    Kalkan, Erol; ,

    2012-01-01

    Building codes in the U.S. require at least two horizontal ground motion components for three-dimensional (3D) response history analysis (RHA) of structures. For sites within 5 km of an active fault, these records should be rotated to fault-normal/fault-parallel (FN/FP) directions, and two RHA analyses should be performed separately (when FN and then FP are aligned with transverse direction of the structural axes). It is assumed that this approach will lead to two sets of responses that envelope the range of possible responses over all non-redundant rotation angles. This assumption is examined here using 3D computer models of a single-story structure having symmetric (that is, torsionally-stiff) and asymmetric (that is, torsionally flexible) layouts subjected to an ensemble of bi-directional near-fault strong ground motions with and without apparent velocity pulses. In this parametric study, the elastic vibration period of the structures is varied from 0.2 to 5 seconds, and yield strength reduction factors R is varied from a value that leads to linear-elastic design to 3 and 5. The influence that the rotation angle of the ground motion has on several engineering demand parameters (EDPs) is examined in linear-elastic and nonlinear-inelastic domains to form a benchmark for evaluating the use of the FN/FP directions as well as the maximum-direction (MD) ground motion, a new definition of horizontal ground motions for use in the seismic design of structures according to the 2009 NEHRP Provisions and Commentary.

  14. Nonlinear supratransmission

    Energy Technology Data Exchange (ETDEWEB)

    Geniet, F; Leon, J [Physique Mathematique et Theorique, CNRS-UMR 5825, 34095 Montpellier (France)

    2003-05-07

    A nonlinear system possessing a natural forbidden band gap can transmit energy of a signal with a frequency in the gap, as recently shown for a nonlinear chain of coupled pendulums (Geniet and Leon 2002 Phys. Rev. Lett. 89 134102). This process of nonlinear supratransmission, occurring at a threshold that is exactly predictable in many cases, is shown to have a simple experimental realization with a mechanical chain of pendulums coupled by a coil spring. It is then analysed in more detail. First we go to different (nonintegrable) systems which do sustain nonlinear supratransmission. Then a Josephson transmission line (a one-dimensional array of short Josephson junctions coupled through superconducting wires) is shown to also sustain nonlinear supratransmission, though being related to a different class of boundary conditions, and despite the presence of damping, finiteness, and discreteness. Finally, the mechanism at the origin of nonlinear supratransmission is found to be a nonlinear instability, and this is briefly discussed here.

  15. External perforated Solar Screens for daylighting in residential desert buildings: Identification of minimum perforation percentages

    KAUST Repository

    Sherif, Ahmed

    2012-06-01

    The desert climate is endowed by clear sky conditions, providing an excellent opportunity for optimum utilization of natural light in daylighting building indoor spaces. However, the sunny conditions of the desert skies, in countries like Egypt and Saudi Arabia, result in the admittance of direct solar radiation, which leads to thermal discomfort and the incidence of undesired glare. One type of shading systems that is used to permit daylight while controlling solar penetration is " Solar Screens" Very little research work addressed different design aspects of external Solar Screens and their influence on daylighting performance, especially in desert conditions, although these screens proved their effectiveness in controlling solar radiation in traditional buildings throughout history.This paper reports on the outcomes of an investigation that studied the influence of perforation percentage of Solar Screens on daylighting performance in a typical residential living room of a building in a desert location. The objective was to identify minimum perforation percentage of screen openings that provides adequate illuminance levels in design-specific cases and all-year-round.Research work was divided into three stages. Stage one focused on the analysis of daylighting illuminance levels in specific dates and times, while the second stage was built on the results of the first stage, and addressed year round performance using Dynamic Daylight Performance Metrics (DDPMs). The third stage addressed the possibility of incidence of glare in specific cases where illuminance levels where found very high in some specific points during the analysis of first stage. The research examined the daylighting performance in an indoor space with a number of assumed fixed experimentation parameters that were chosen to represent the principal features of a typical residential living room located in a desert environment setting.Stage one experiments demonstrated that the screens fulfilled the

  16. The Nonlinear Magnetosphere: Expressions in MHD and in Kinetic Models

    Science.gov (United States)

    Hesse, Michael; Birn, Joachim

    2011-01-01

    Like most plasma systems, the magnetosphere of the Earth is governed by nonlinear dynamic evolution equations. The impact of nonlinearities ranges from large scales, where overall dynamics features are exhibiting nonlinear behavior, to small scale, kinetic, processes, where nonlinear behavior governs, among others, energy conversion and dissipation. In this talk we present a select set of examples of such behavior, with a specific emphasis on how nonlinear effects manifest themselves in MHD and in kinetic models of magnetospheric plasma dynamics.

  17. The effect of non-local higher order stress to predict the nonlinear vibration behavior of carbon nanotube conveying viscous nanoflow

    Science.gov (United States)

    Mohammadimehr, M.; Mohammadi-Dehabadi, A. A.; Maraghi, Z. Khoddami

    2017-04-01

    In this research, the effect of non-local higher order stress on the nonlinear vibration behavior of carbon nanotube conveying viscous nanoflow resting on elastic foundation is investigated. Physical intuition reveals that increasing nanoscale stress leads to decrease the stiffness of nanostructure which firstly established by Eringen's non-local elasticity theory (previous nonlocal method) while many of papers have concluded otherwise at microscale based on modified couple stress, modified strain gradient theories and surface stress effect. The non-local higher order stress model (new nonlocal method) is used in this article that has been studied by few researchers in other fields and the results from the present study show that the trend of the new nonlocal method and size dependent effect including modified couple stress theory is the same. In this regard, the nonlinear motion equations are derived using a variational principal approach considering essential higher-order non-local terms. The surrounded elastic medium is modeled by Pasternak foundation to increase the stability of system where the fluid flow may cause system instability. Effects of various parameters such as non-local parameter, elastic foundation coefficient, and fluid flow velocity on the stability and dimensionless natural frequency of nanotube are investigated. The results of this research show that the small scale parameter based on higher order stress help to increase the natural frequency which has been approved by other small scale theories such as strain gradient theory, modified couple stress theory and experiments, and vice versa for previous nonlocal method. This study may be useful to measure accurately the vibration characteristics of nanotubes conveying viscous nanoflow and to design nanofluidic devices for detecting blood Glucose.

  18. The effect of non-local higher order stress to predict the nonlinear vibration behavior of carbon nanotube conveying viscous nanoflow

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadimehr, M., E-mail: mmohammadimehr@kashanu.ac.ir [Department of Solid Mechanics, Faculty of Mechanical Engineering, University of Kashan, P.O. Box: 87317-53153, Kashan (Iran, Islamic Republic of); Mohammadi-Dehabadi, A.A. [Department of Solid Mechanics, Faculty of Mechanical Engineering, University of Kashan, P.O. Box: 87317-53153, Kashan (Iran, Islamic Republic of); Department of Mechanical Engineering, Iran University of Science and Technology, Narmak, Tehran (Iran, Islamic Republic of); Maraghi, Z. Khoddami [Department of Solid Mechanics, Faculty of Mechanical Engineering, University of Kashan, P.O. Box: 87317-53153, Kashan (Iran, Islamic Republic of)

    2017-04-01

    In this research, the effect of non-local higher order stress on the nonlinear vibration behavior of carbon nanotube conveying viscous nanoflow resting on elastic foundation is investigated. Physical intuition reveals that increasing nanoscale stress leads to decrease the stiffness of nanostructure which firstly established by Eringen's non-local elasticity theory (previous nonlocal method) while many of papers have concluded otherwise at microscale based on modified couple stress, modified strain gradient theories and surface stress effect. The non-local higher order stress model (new nonlocal method) is used in this article that has been studied by few researchers in other fields and the results from the present study show that the trend of the new nonlocal method and size dependent effect including modified couple stress theory is the same. In this regard, the nonlinear motion equations are derived using a variational principal approach considering essential higher-order non-local terms. The surrounded elastic medium is modeled by Pasternak foundation to increase the stability of system where the fluid flow may cause system instability. Effects of various parameters such as non-local parameter, elastic foundation coefficient, and fluid flow velocity on the stability and dimensionless natural frequency of nanotube are investigated. The results of this research show that the small scale parameter based on higher order stress help to increase the natural frequency which has been approved by other small scale theories such as strain gradient theory, modified couple stress theory and experiments, and vice versa for previous nonlocal method. This study may be useful to measure accurately the vibration characteristics of nanotubes conveying viscous nanoflow and to design nanofluidic devices for detecting blood Glucose.

  19. External perforated window Solar Screens: The effect of screen depth and perforation ratio on energy performance in extreme desert environments

    KAUST Repository

    Sherif, A.

    2012-09-01

    In hot arid desert environments, the solar radiation passing through windows increases the cooling loads and the energy consumption of buildings. Shading of windows can reduce these loads. Unlike the woven solar screens, wooden solar screens have a thickness that provides selective shading properties. Perforated wooden solar screens were traditionally used for windows shading. Developing modern types of these shading systems can lead to significant energy savings. The paper addresses the influence of changing the perforation percentage and depth of these screens on the annual energy loads, hence defining the optimum depth/perforation configurations for various window orientations. Series of experiments were performed using the EnergyPlus simulation software for a typical residential building in the Kharga Oasis, located in the Egyptian desert. A range of perforation percentages and depths were tested. Conclusions prove that external fixed deep perforated solar screens could effectively achieve energy savings up to 30% of the total energy consumption in the West and South orientations. Optimum range of depths and perforation percentages were recommended. These are: 80-90% perforation rate and 1:1 depth/opening width ratio. These lighter and deeper solar screen configurations were found to be more efficient in energy consumption in comparison with the traditional ones. © 2012 Elsevier B.V. All rights reserved.

  20. Existence and Global Asymptotic Behavior of Positive Solutions for Nonlinear Fractional Dirichlet Problems on the Half-Line

    Directory of Open Access Journals (Sweden)

    Imed Bachar

    2014-01-01

    Full Text Available We are interested in the following fractional boundary value problem: Dαu(t+atuσ=0, t∈(0,∞, limt→0⁡t2-αu(t=0, limt→∞⁡t1-αu(t=0, where 1<α<2, σ∈(-1,1, Dα is the standard Riemann-Liouville fractional derivative, and a is a nonnegative continuous function on (0,∞ satisfying some appropriate assumptions related to Karamata regular variation theory. Using the Schauder fixed point theorem, we prove the existence and the uniqueness of a positive solution. We also give a global behavior of such solution.