Kim, Heung Soo; Sohn, Jung Woo; Jeon, Juncheol; Choi, Seung-Bok
2013-02-06
In this work, active vibration control of an underwater cylindrical shell structure was investigated, to suppress structural vibration and structure-borne noise in water. Finite element modeling of the submerged cylindrical shell structure was developed, and experimentally evaluated. Modal reduction was conducted to obtain the reduced system equation for the active feedback control algorithm. Three Macro Fiber Composites (MFCs) were used as actuators and sensors. One MFC was used as an exciter. The optimum control algorithm was designed based on the reduced system equations. The active control performance was then evaluated using the lab scale underwater cylindrical shell structure. Structural vibration and structure-borne noise of the underwater cylindrical shell structure were reduced significantly by activating the optimal controller associated with the MFC actuators. The results provide that active vibration control of the underwater structure is a useful means to reduce structure-borne noise in water.
Directory of Open Access Journals (Sweden)
Seung-Bok Choi
2013-02-01
Full Text Available In this work, active vibration control of an underwater cylindrical shell structure was investigated, to suppress structural vibration and structure-borne noise in water. Finite element modeling of the submerged cylindrical shell structure was developed, and experimentally evaluated. Modal reduction was conducted to obtain the reduced system equation for the active feedback control algorithm. Three Macro Fiber Composites (MFCs were used as actuators and sensors. One MFC was used as an exciter. The optimum control algorithm was designed based on the reduced system equations. The active control performance was then evaluated using the lab scale underwater cylindrical shell structure. Structural vibration and structure-borne noise of the underwater cylindrical shell structure were reduced significantly by activating the optimal controller associated with the MFC actuators. The results provide that active vibration control of the underwater structure is a useful means to reduce structure-borne noise in water.
Directory of Open Access Journals (Sweden)
ZHANG Kai
2017-08-01
Full Text Available Statistical Energy Analysis(SEAis an effective method for solving high frequency structural vibration and acoustic radiation problems. When we use it to analyze submerged structures, it is necessary to consider the actions of fluid as'heavy fluid' relative to structures, which differs from when it is used in the air. The simple model of a submerged cylindrical shell is used to calculate at a higher frequency using FEM/BEM. The SEA and FEM method are then used to calculate the radiation sound pressure level, verifying the accuracy of the SEA prediction for submerged structures. The classified method of subsystems and the effect of the error of the internal loss factor on the accuracy of the results are explored. The calculated results of SEA and FEM/BEM are very different below 400 Hz, and basically the same above 400 Hz. The error caused by the division of different subsystems is about 5 dB. The error in the calculation results caused by the error of the internal loss factor is 2-3 dB. It is possible to use SEA to calculate the radiated noise of an underwater cylindrical shell when the modal density is high enough.For the cylindrical shell, dividing the subsystems along the circumference is not reliable at a low frequency, as it may lead to inaccurate calculation results. At a high frequency, it is more accurate to divide the subsystems along the circumference than the axle. For subsystems with high energy, the internal loss factor has a greater effect on the simulation results, so a more accurate way should be taken to determine the internal loss factor of subsystems with high energy.
Sound Radiation of Cylindrical Shells
Directory of Open Access Journals (Sweden)
B Alzahabi
2016-09-01
Full Text Available The acoustic signature of submarines is very critical in such high performance structure. Submarines are not only required to sustain very high dynamic loadings at all time, but also being able maneuver and perform their functions under sea without being detected by sonar systems. Submarines rely on low acoustic signature level to remain undetected. Reduction of sound radiation is most efficiently achieved at the design stage. Acoustic signatures may be determined by considering operational scenarios, and modal characteristics. The acoustic signature of submarines is generally of two categories; broadband which has a continuous spectrum; and a tonal noise which has discrete frequencies. The nature of sound radiation of submarine is fiction of its speed. At low speed the acoustic signature is dominated by tonal noise, while at high speed, the acoustic signature is mainly dominated by broadband noise. Submarine hulls are mainly constructed of circular cylindrical shells. Unlike that of simpler structures such as beams and plates, the modal spectrum of cylindrical shell exhibits very unique characteristics. Mode crossing, the uniqueness of modal spectrum, and the redundancy of modal constraints are just to name a few. In cylindrical shells, the lowest natural frequency is not necessarily associated with the lowest wave index. In fact, the natural frequencies do not fall in ascending order of the wave index either. Solution of the vibration problem of cylindrical shells also indicates repeated natural frequencies. These modes are referred to as double peak frequencies. Mode shapes associated with each one of the natural frequencies are usually a combination of Radial (flexural, Longitudinal (axial, and Circumferential (torsional modes. In this paper, the wave equation will be set up in terms of the pressure fluctuations, p(x, t. It will be demonstrated that the noise radiation is a fluctuating pressure wave.
Structural and Acoustic Responses of a Submerged Stiffened Conical Shell
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Meixia Chen
2014-01-01
Full Text Available This paper studies the vibrational behavior and far-field sound radiation of a submerged stiffened conical shell at low frequencies. The solution for the dynamic response of the conical shell is presented in the form of a power series. A smeared approach is used to model the ring stiffeners. Fluid loading is taken into account by dividing the conical shell into narrow strips which are considered to be local cylindrical shells. The far-field sound pressure is solved by the Element Radiation Superposition Method. Excitations in two directions are considered to simulate the loading on the surface of the conical shell. These excitations are applied along the generator and normal to the surface of the conical shell. The contributions from the individual circumferential modes on the structural responses of the conical shell are studied. The effects of the external fluid loading and stiffeners are discussed. The results from the analytical models are validated by numerical results from a fully coupled finite element/boundary element model.
OPTIMAL THICKNESS OF A CYLINDRICAL SHELL
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Paul Ziemann
2015-01-01
Full Text Available In this paper an optimization problem for a cylindrical shell is discussed. The aim is to look for an optimal thickness of a shell to minimize the deformation under an applied external force. As a side condition, the volume of the shell has to stay constant during the optimization process. The deflection is calculated using an approach from shell theory. The resulting control-to-state operator is investigated analytically and a corresponding optimal control problem is formulated. Moreover, necessary conditions for an optimal solution are stated and numerical solutions are presented for different examples.
Indentation of ellipsoidal and cylindrical elastic shells.
Vella, Dominic; Ajdari, Amin; Vaziri, Ashkan; Boudaoud, Arezki
2012-10-05
Thin shells are found in nature at scales ranging from viruses to hens' eggs; the stiffness of such shells is essential for their function. We present the results of numerical simulations and theoretical analyses for the indentation of ellipsoidal and cylindrical elastic shells, considering both pressurized and unpressurized shells. We provide a theoretical foundation for the experimental findings of Lazarus et al. [following paper, Phys. Rev. Lett. 109, 144301 (2012)] and for previous work inferring the turgor pressure of bacteria from measurements of their indentation stiffness; we also identify a new regime at large indentation. We show that the indentation stiffness of convex shells is dominated by either the mean or Gaussian curvature of the shell depending on the pressurization and indentation depth. Our results reveal how geometry rules the rigidity of shells.
Indentation of Ellipsoidal and Cylindrical Elastic Shells
Vella, Dominic
2012-10-01
Thin shells are found in nature at scales ranging from viruses to hens\\' eggs; the stiffness of such shells is essential for their function. We present the results of numerical simulations and theoretical analyses for the indentation of ellipsoidal and cylindrical elastic shells, considering both pressurized and unpressurized shells. We provide a theoretical foundation for the experimental findings of Lazarus etal. [following paper, Phys. Rev. Lett. 109, 144301 (2012)PRLTAO0031-9007] and for previous work inferring the turgor pressure of bacteria from measurements of their indentation stiffness; we also identify a new regime at large indentation. We show that the indentation stiffness of convex shells is dominated by either the mean or Gaussian curvature of the shell depending on the pressurization and indentation depth. Our results reveal how geometry rules the rigidity of shells. © 2012 American Physical Society.
Fluid-structure coupled analysis of underwater cylindrical shells
Ai, Shang-Mao; Sun, Li-Ping
2008-06-01
Underwater cylindrical shell structures have been found a wide of application in many engineering fields, such as the element of marine, oil platforms, etc. The coupled vibration analysis is a hot issue for these underwater structures. The vibration characteristics of underwater structures are influenced not only by hydrodynamic pressure but also by hydrostatic pressure corresponding to different water depths. In this study, an acoustic finite element method was used to evaluate the underwater structures. Taken the hydrostatic pressure into account in terms of initial stress stiffness, an acoustical fluid-structure coupled analysis of underwater cylindrical shells has been made to study the effect of hydrodynamic pressures on natural frequency and sound radiation. By comparing with the frequencies obtained by the acoustic finite element method and by the added mass method based on the Bessel function, the validity of present analysis was checked. Finally, test samples of the sound radiation of stiffened cylindrical shells were acquired by a harmonic acoustic analysis. The results showed that hydrostatic pressure plays an important role in determining a large submerged body motion, and the characteristics of sound radiation change with water depth. Furthermore, the analysis methods and the results are of significant reference value for studies of other complicated submarine structures.
Multimode interaction in axially excited cylindrical shells
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Silva F. M. A.
2014-01-01
Full Text Available Cylindrical shells exhibit a dense frequency spectrum, especially near the lowest frequency range. In addition, due to the circumferential symmetry, frequencies occur in pairs. So, in the vicinity of the lowest natural frequencies, several equal or nearly equal frequencies may occur, leading to a complex dynamic behavior. So, the aim of the present work is to investigate the dynamic behavior and stability of cylindrical shells under axial forcing with multiple equal or nearly equal natural frequencies. The shell is modelled using the Donnell nonlinear shallow shell theory and the discretized equations of motion are obtained by applying the Galerkin method. For this, a modal solution that takes into account the modal interaction among the relevant modes and the influence of their companion modes (modes with rotational symmetry, which satisfies the boundary and continuity conditions of the shell, is derived. Special attention is given to the 1:1:1:1 internal resonance (four interacting modes. Solving numerically the governing equations of motion and using several tools of nonlinear dynamics, a detailed parametric analysis is conducted to clarify the influence of the internal resonances on the bifurcations, stability boundaries, nonlinear vibration modes and basins of attraction of the structure.
Free vibrations of circular cylindrical shells
Armenàkas, Anthony E; Herrmann, George
1969-01-01
Free Vibrations of Circular Cylindrical Shells deals with thin-walled structures that undergo dynamic loads application, thereby resulting in some vibrations. Part I discusses the treatment of problems associated with the propagation of plane harmonic waves in a hollow circular cylinder. In such search for solutions, the text employs the framework of the three-dimensional theory of elasticity. The text explains the use of tables of natural frequencies and graphs of representative mode shapes of harmonic elastic waves bounding in an infinitely long isotropic hollow cylinder. The tables are
Forced Vibration Analysis for a FGPM Cylindrical Shell
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Hong-Liang Dai
2013-01-01
Full Text Available This article presents an analytical study for forced vibration of a cylindrical shell which is composed of a functionally graded piezoelectric material (FGPM. The cylindrical shell is assumed to have two-constituent material distributions through the thickness of the structure, and material properties of the cylindrical shell are assumed to vary according to a power-law distribution in terms of the volume fractions for constituent materials, the exact solution for the forced vibration problem is presented. Numerical results are presented to show the effect of electric excitation, thermal load, mechanical load and volume exponent on the static and force vibration of the FGPM cylindrical shell. The goal of this investigation is to optimize the FGPM cylindrical shell in engineering, also the present solution can be used in the forced vibration analysis of cylindrical smart elements.
Thermoelastoplastic deformation of noncircular cylindrical shells
Merzlyakov, V. A.
2008-08-01
A method to determine the nonstationary temperature fields and the thermoelastoplastic stress-strain state of noncircular cylindrical shells is developed. It is assumed that the physical and mechanical properties are dependent on temperature. The heat-conduction problem is solved using an explicit difference scheme. The temperature variation throughout the thickness is described by a power polynomial. For the other two coordinates, finite differences are used. The thermoplastic problem is solved using the geometrically nonlinear theory of shells based on the Kirchhoff-Love hypotheses. The theory of simple processes with deformation history taken into account is used. Its equations are linearized by a modified method of elastic solutions. The governing system of partial differential equations is derived. Variables are separated in the case where the curvilinear edges are hinged. The partial case where the stress-strain state does not change along the generatrix is examined. The systems of ordinary differential equations obtained in all these cases are solved using Godunov's discrete orthogonalization. The temperature field in a shell with elliptical cross-section is studied. The stress-strain state found by numerical integration along the generatrix is compared with that obtained using trigonometric Fourier series. The effect of a Winkler foundation on the stress-strain state is analyzed
On the accuracy of the asymptotic theory for cylindrical shells
DEFF Research Database (Denmark)
Niordson, Frithiof; Niordson, Christian
1999-01-01
We study the accuracy of the lowest-order bending theory of shells, derived from an asymptotic expansion of the three-dimensional theory of elasticity, by comparing the results of this shell theory for a cylindrical shell with clamped ends with the results of a solution to the three......-dimensional problem. The results are also compared with those of some commonly used engineering shell theories....
Gravitational collapse of a cylindrical null shell in vacuum
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S. Khakshournia
2008-03-01
Full Text Available Barrabès-Israel null shell formalism is used to study the gravitational collapse of a thin cylindrical null shell in vacuum. In general the lightlike matter shell whose history coincides with a null hypersurface is characterized by a surface energy density. In addition, a gravitational impulsive wave is present on this null hypersurface whose generators admit both the shear and expansion. In the case of imposing the cylindrical flatness the surface energy-momentum tensor of the matter shell on the null hypersurface vanishes and the null hyper- surface is just the history of the gravitational wave .
The Structural Response of Cylindrical Shells to Internal Shock Loading
Beltman, W.M.; Burcsu, E.N.; Shepherd, J.E.; Zuhal, L.
The internal shock loading of cylindrical shells can be represented as a step load advancing at constant speed. Several analytical models are available to calculate the structural response of shells to this type of loading. These models show that the speed of the shock wave is an important
Experimental investigations on buckling of cylindrical shells under ...
Indian Academy of Sciences (India)
This paper presents experimental studies on buckling of cylindrical shell models under axial and transverse shear loads. Tests are carried out using an experimental facility specially designed, fabricated and installed, with provision for in-situ measurement of the initial geometric imperfections. The shell models are made by ...
On the accuracy of the asymptotic theory for cylindrical shells
DEFF Research Database (Denmark)
Niordson, Frithiof; Niordson, Christian
1999-01-01
We study the accuracy of the lowest-order bending theory of shells, derived from an asymptotic expansion of the three-dimensional theory of elasticity, by comparing the results of this theory for a cylindrical shell with clamped ends with the results of a solution to the three-dimensional problem....... The results are also compared with those of some commonly used engineering shell theories....
Kwak, Moon K.; Yang, Dong-Ho
2013-09-01
This paper is concerned with the suppression of vibrations and radiated sound of a ring-stiffened circular cylindrical shell in contact with unbounded external fluid by means of piezoelectric sensors and actuators. The dynamic model of a circular cylindrical shell based on the Sanders shell theory was considered together with a ring stiffener model. The mass and stiffness matrices for a ring stiffener were newly derived in this study and added to the mass and stiffness matrices of the cylindrical shell, respectively. The fluid-added mass matrix, which was derived by using the baffled shell theory, was also added to the mass matrix. Finally, the equations representing the piezoelectric sensor measurement and piezoelectric actuation complete the theoretical model for the addressed problem. The natural vibration characteristics of the ring-stiffened cylindrical shell both in air and in water were investigated both theoretically and experimentally. The theoretical predictions were in good agreement with the experimental results. An active vibration controller which can cope with a harmonic disturbance was designed by considering the modified higher harmonic control, which is, in fact, a band rejection filter. An active vibration control experiment on the submerged cylindrical shell was carried out in a water tank and the digital control system was used. The experimental results showed that both vibrations and radiation sound of the submerged cylindrical shell were suppressed by a pair of piezoelectric sensor and actuator.
Plasticity around an Axial Surface Crack in a Cylindrical Shell
DEFF Research Database (Denmark)
Krenk, Steen
1979-01-01
field in an axially cracked cylindrical shell arising from use of classical eighth order shallow shell theory is removed when use is made of a tenth order shell theory which accounts for transverse shear deformations. Although the membrane stresses are only moderately affected, the influence...... and Ratwani,3–5 it generalises Dugdale's assumption of a concentrated yield zone in the plane of the crack but, contrary to that model, transverse shear effects are included and a continuous stress distribution is assumed in the yield zone. The inherent difficulties arising from the use of shell theory...
Evolution of bulk strain solitons in cylindrical inhomogeneous shells
Energy Technology Data Exchange (ETDEWEB)
Shvartz, A., E-mail: andrew.shvartz@mail.ioffe.ru; Samsonov, A.; Dreiden, G.; Semenova, I. [Ioffe Institute, 26 Politekhnicheskaya, St Petersburg 194021 (Russian Federation)
2015-10-28
Bulk strain solitary waves in nonlinearly elastic thin-walled cylindrical shells with variable geometrical and physical parameters are studied, and equation for the longitudinal strain component with the variable coefficients is derived. A conservative finite difference scheme is proposed, and the results of numerical simulation of the strain soliton evolution in a shell with the abrupt variations of cross section and physical properties of the material are presented.
Static Analysis of Circular Cylindrical Shell Under Hydrostatic and ...
African Journals Online (AJOL)
Analysis of circular cylindrical shell under the action of hydrostatic and stiffening ring forces is carried out in this work. The differential equation of equilibrium, similar to that of beam on elastic foundation, was obtained from static principles on the assumptions of P. L. Pasternak. The initial value method was used to solve the ...
Analysis of radial vibrations of poroelastic circular cylindrical shells ...
African Journals Online (AJOL)
Waves propagating in radial direction of a poroelastic circular cylinder are termed as radial vibrations. Radial vibrations of poroelastic circular cylindrical shell of infinite extent immersed in an inviscid elastic fluid are examined employing Biot's theory. Biot's model consists of an elastic matrix permeated by a network of ...
On the dynamic buckling of lightly damped cylindrical shells ...
African Journals Online (AJOL)
The dynamic buckling load of finite imperfect, lightly but viscously damped cylindrical shells subjected to a periodic load, is determined using the technique of multiple scaling (two-timing) regular perturbation analysis. The geometric imperfection, assumed deterministic, are also assumed small and are expanded in a double ...
Tunable cylindrical shell as an element in acoustic metamaterial
Titovich, Alexey S
2014-01-01
Elastic cylindrical shells are fitted with an internal mechanism which is optimized so that, in the quasi-static regime, the combined system exhibits prescribed effective acoustic properties. The mechanism consists of a central mass supported by an axisymmetric distribution of elastic stiffeners. By appropriate selection of the mass and stiffness of the internal mechanism, the shell's effective acoustic properties (bulk modulus and density) can be tuned as desired. Subsonic flexural waves excited in the shell by the attachment of stiffeners are suppressed by including a sufficiently large number of such stiffeners. Effectiveness of the proposed metamaterial is demonstrated by matching the properties of a thin aluminum shell with a polymer insert to those of water. The scattering cross section in water is nearly zero over a broad range of frequencies at the lower end of the spectrum. By arranging the tuned shells in an array the resulting acoustic metamaterial is capable of steering waves. As an example, a cyl...
Numerical modeling of micropolar cylindrical shells on supercomputers with GPUs
Varygina, M.
2017-10-01
The mathematical model of micropolar cylindrical shells is considered within the framework of the approximation approach. The constitutive equations of the theory are written in symmetric hyperbolic form. For the solution of dynamic problems on wave propagation in micropolar shells, parallel numerical algorithm based on the space-variable two-cyclic splitting method in combination with the monotone ENO-scheme is proposed. The parallelization of computations is performed with the CUDA technology for supercomputers with GPUs. The results of numerical solution of the problems on the action of distributed impulse loads and concentrated instant loads are shown.
Dynamic characteristics of a partially fluid-filled cylindrical shell
Energy Technology Data Exchange (ETDEWEB)
Jhung, Myung Jo; Yu, Seon Oh [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of); Lim, Yeong Taek [Tae Sung S and E Inc., Seoul (Korea, Republic of)
2011-03-15
A pressurizer in a small integral type pressurized water reactor is located inside the upper region of the reactor vessel, and uses a space between the upper head of the reactor vessel and the upper region of the upper guide structure which is partially filled with fluid depending on the operating power. This new design requires a comprehensive investigation of vibration characteristics. This study investigates the modal characteristics of a pressurizer which uses a simplified cylindrical shell model, focusing on how having fluid in the shell affects vibration and response characteristics. In addition, an analysis of sloshing is performed and the response characteristics are addressed
Natural frequency of a circular cylindrical shell filled with fluid
Energy Technology Data Exchange (ETDEWEB)
Jeong, Kyeong Hoon; Kim, Tae Wan; Kim, Kang Soo; Park, Keun Bae [Korea Atomic Energy Research Institute, Taejon (Korea)
1998-08-01
This report presents an analytical method for evaluating the free vibration of a circular cylindrical shell filled with bounded compressible fluid. The analytical method was developed by means of the finite Fourier series expansion method. The compressible fluid motion was determined by means of the linear velocity potential theory. To clarify the validity of the analytical method, the natural frequencies of a circular cylindrical shell with the clamped-clamped boundary condition, and filled with water, were obtained by the analytical method and the finite element method using a commercial ANSYS 5.2 software. Excellent agreement on the natural frequencies of the fluid-filled shell structure was found. The compressibility and density of fluid effects the normalized coupled natural frequencies were investigated. The density of fluid affects on all coupled natural frequencies of the shell,, whereas the compressibility and bounding of fluid affects mainly on the natural frequencies of lower circumferential modes. The theory developed in this report will be applicable to the dynamic analysis of a core support barrel in SMART integral reactor filled with coolant. (author). 15 refs., 14 figs., 1 tab.
Buckling and vibration of circular cylindrical shells containing hot liquid
Ganesan, N.; Pradeep, V.
2005-11-01
Cylindrical shell filled with hot liquid is analyzed for buckling and vibration behavior using semi-analytical finite element method. A parametric study is conducted on a 316L stainless-steel cylinder filled with hot liquid. The temperature distribution in shell domain is obtained by using axisymmetric eight-node ring finite elements, capable of taking axial variation of temperature into account. Three-node ring elements are used for buckling and vibration analysis, formulated using semi-analytical finite element method. Thermal stress resultants and moment resultants in the shell are estimated and static buckling analysis is carried out to find the buckling temperature of the container for different levels of filling of liquid and for two different boundary conditions. Free vibration analysis carried out by considering initial stress effect and added mass effect due to hot liquid. Two different geometries are considered to study the effect of geometry on buckling temperature.
Prediction of Vibrational Behavior of Grid-Stiffened Cylindrical Shells
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G. H. Rahimi
2014-01-01
Full Text Available A unified analytical approach is applied to investigate the vibrational behavior of grid-stiffened cylindrical shells with different boundary conditions. A smeared method is employed to superimpose the stiffness contribution of the stiffeners with those of shell in order to obtain the equivalent stiffness parameters of the whole panel. Theoretical formulation is established based on Sanders’ thin shell theory. The modal forms are assumed to have the axial dependency in the form of Fourier series whose derivatives are legitimized using Stoke's transformation. A 3D finite element model is also built using ABAQUS software which takes into consideration the exact geometric configuration of the stiffeners and the shell. The achievements from the two types of analyses are compared with each other and good agreement has been obtained. The Influences of variations in shell geometrical parameters, boundary condition, and changes in the cross stiffeners angle on the natural frequencies are studied. The results obtained are novel and can be used as a benchmark for further studies. The simplicity and the capability of the present method are also discussed.
Effects of Shell-Buckling Knockdown Factors in Large Cylindrical Shells
Hrinda, Glenn A.
2012-01-01
Shell-buckling knockdown factors (SBKF) have been used in large cylindrical shell structures to account for uncertainty in buckling loads. As the diameter of the cylinder increases, achieving the manufacturing tolerances becomes increasingly more difficult. Knockdown factors account for manufacturing imperfections in the shell geometry by decreasing the allowable buckling load of the cylinder. In this paper, large-diameter (33 ft) cylinders are investigated by using various SBKF's. An investigation that is based on finite-element analysis (FEA) is used to develop design sensitivity relationships. Different manufacturing imperfections are modeled into a perfect cylinder to investigate the effects of these imperfections on buckling. The analysis results may be applicable to large- diameter rockets, cylindrical tower structures, bulk storage tanks, and silos.
Directory of Open Access Journals (Sweden)
GUO Wenjie
2017-08-01
Full Text Available Aiming at the current lack of analytical research concerning the cylindrical shell-flow field coupling vibration and sound radiation system under the influence of a free surface, this paper proposes an analytical method which solves the vibration response and far-field acoustic radiation of a finite cylindrical shell immersed at a finite depth. Based on the image method and Graf addition theorem, the analytical expression of the fluid velocity potential can be obtained, then combined with the energy functional of the variation method to deduce the shell-liquid coupling vibration equation, which can in turn solve the forced vibration response. The research shows that, compared with an infinite fluid, a free surface can increase at the same order of resonance frequency; but as the depth of immersion gradually increases, the mean square vibration velocity tends to become the same as that in an infinite fluid. Compared with numerical results from Nastran software, this shows that the present method is accurate and reliable, and has such advantages as a simple method and a small amount of calculation. The far-field radiated pressure can be obtained by the vibration response using the Fourier transformation and stationary phase method. The results indicate that the directivity and volatility of the far-field acoustic pressure of a cylindrical shell is similar to that of an acoustical dipole due to the free surface. However, the far-field acoustic pressure is very different from the vibration characteristics, and will not tend to an infinite fluid as the submerging depth increases. Compared with the numerical method, the method in this paper is simpler and has a higher computational efficiency. It enables the far-field acoustic radiation of an underwater cylindrical shell to be predicted quickly under the influence of external incentives and the free surface, providing guiding significance for acoustic research into the half space structure vibration
Uğurlu, B.; Ergin, A.
2008-12-01
This paper presents the effects of different end conditions on the response behavior of thin circular cylindrical shell structures fully in contact with flowing fluid. The investigated end conditions are as follows: simply supported, clamped-clamped, clamped-simply supported and clamped-free (cantilever shell) ends. Additionally, the dynamic responses of a tapered cylindrical shell conveying flowing fluid and simply supported at its ends were investigated. The method employed in this study is a hybrid method—a boundary integral equation method for the calculation of the fluid-structure interaction effects and a finite element method for the structural analysis. In this study, the mathematical model presented before [B. Uğurlu, A. Ergin, A hydroelasticity method for vibrating structures containing and/or submerged in flowing fluid, Journal of Sound and Vibration 290 (2006) 572-596] is extended by applying the direct boundary integral equation method, and by using a higher-order panel method (linear distribution). It should also be said that the method used in this study could be applied to any shape of cylindrical structure in contact with internal and/or external flowing fluid, in contrast to the studies found in the literature. In the analysis of the linear fluid-structure system, it is assumed that the fluid is ideal, i.e., inviscid, incompressible and its motion is irrotational. It is assumed that the flexible structure vibrates in its in-vacuo modes when it is in contact with flowing fluid, and that each mode gives rise to a corresponding surface pressure distribution on the wetted surface of the structure. The in-vacuo dynamic properties of the dry structure are obtained by using a standard finite element software. In the wet part of the analysis, the wetted surface is idealized by using appropriate boundary elements, referred to as hydrodynamic panels. The fluid-structure interaction forces are calculated in terms of the generalized added mass coefficients
Resonant Excitation of a Truncated Metamaterial Cylindrical Shell by a Thin Wire Monopole
DEFF Research Database (Denmark)
Kim, Oleksiy S.; Erentok, Aycan; Breinbjerg, Olav
2009-01-01
A truncated metamaterial cylindrical shell excited by a thin wire monopole is investigated using the integral equation technique as well as the finite element method. Simulations reveal a strong field singularity at the edge of the truncated cylindrical shell, which critically affects the matching...
Anomalous sound absorption in lattices of cylindrical perforated shells
García-Chocano, Victor M.; Sánchez-Dehesa, José
2015-03-01
This work reports the enhancement of sound absorption by sonic crystals slabs made of cylindrical perforated shells. These building units, with perforations of millimeter size, show small losses and cannot explain the strong absorption observed at some specific frequencies when the slabs consist of just a few number of rows. It is found that this phenomenon is due to a resonant Wood anomaly which occurs when the incident wave couples with a leaky guided mode supported by the slab. This effect results in an enhancement of the absorption, since the energy transferred to the guided mode travels within the slab, along a direction perpendicular to the incident one. Multiple scattering and finite element simulations give support to the proposed behavior, the transmittance results being in good agreement with experimental data previously reported.
Stress Analysis of Composite Cylindrical Shells With an Elliptical Cutout
Nemeth, M. P.; Oterkus, E.; Madenci, E.
2005-01-01
A special-purpose, semi-analytical solution method for determining the stress and deformation fields in a thin laminated-composite cylindrical shell with an elliptical cutout is presented. The analysis includes the effects of cutout size, shape, and orientation; nonuniform wall thickness; oval-cross-section eccentricity; and loading conditions. The loading conditions include uniform tension, uniform torsion, and pure bending. The analysis approach is based on the principle of stationary potential energy and uses Lagrange multipliers to relax the kinematic admissibility requirements on the displacement representations through the use of idealized elastic edge restraints. Specifying appropriate stiffness values for the elastic extensional and rotational edge restraints (springs) allows the imposition of the kinematic boundary conditions in an indirect manner, which enables the use of a broader set of functions for representing the displacement fields. Selected results of parametric studies are presented for several geometric parameters that demonstrate that analysis approach is a powerful means for developing design criteria for laminated-composite shells.
Deformation analysis of horizontal stiffened cylindrical shells under the effects of gravity
Directory of Open Access Journals (Sweden)
LIU Dong
2017-01-01
Full Text Available In order to study the deformation of submarine pressure hulls under the effects of gravity,a sim-ple calculation formula of the deformation of the free ends of stiffened cylindrical shells is derived based on moment theory and non-moment theory,and the calculated results are compared with the results of Finite Element Analysis(FEAwhich tests the reliability of the formula. The results show that when a thin-wall cylindrical shell simply supported at the bottom is affected by its own gravity,the deformation degree at the free end is directly proportional to the fourth power of the inner diameter of the cylindrical shell,and in-versely proportional to the square of the wall thickness;for cantilever cylindrical shells,the gravity load has little effect on the roundness of the free end plane. With the nonlinear increase of distance between the free end and fixed supporting end,the increase rate increases gradually. With the increase of the inner di-ameter of the cylindrical shell,the deformation degree of the free end decreases gradually. When the inner diameter of the cylindrical shell is 0.75 times its longitudinal length,the deformation degree of the free end is at a minimum,then increases gradually as the inner diameter increases. The gravity deformation calcula-tion of ring stiffened cylindrical shells in a horizontal state and the strengthening measures can provide ref-erences for further study.
Kozyreff, Gregory; Acharyya, Nirmalendu
2016-12-12
We derive formulas for whispering gallery mode resonances and bending losses in infinite cylindrical dielectric shells and sets of concentric cylindrical shells. The formulas also apply to spherical shells and to sections of bent waveguides. The derivation is based on a Wentzel-Kramers-Brillouin (WKB) treatment of Helmholtz equation and can in principle be extended to any number of concentric shells. A distinctive limit analytically arises in the analysis when two shells are brought at very close distance to one another. In that limit, the two shells act as a slot waveguide. If the two shells are sufficiently apart, we identify a structural resonance between the individual shells, which can either lead to a substantial enhancement or suppression of radiation losses.
Damage Characteristics of Coated Cylindrical Shells Subjected to Underwater Contact Explosion
Directory of Open Access Journals (Sweden)
Zhi-fan Zhang
2014-01-01
Full Text Available It is of great significance for the protective design of submarine to study the influences of coverings on the damage characteristics of single and double cylindrical shells subjected to underwater contact explosions. The SPH models of single and double cylindrical shells coated with foam silicone rubber are established to analyze shockwave propagation, damage characteristics, and elastoplastic responses, which provides reasonable parameters of covering position and thickness. The results can be concluded as follows: the superposition of multiple waves may cause the inhomogeneity and discontinuity; for the single cylindrical shell with inner or outer coverings, the damage mode is mainly tensile and shear failure is caused by detonation waves and detonation products; compared with out-covering approach, the in-covering approach has better antishock performance; the best protective effect comes out when the thickness of covering is close to that of the shell; as for the double cylindrical shell without interlayer water, the destruction of inner shell mainly results from the puncture of high-speed fragments from the outer shell, so for the outer shell, out-covering is a better choice; however, since the interlayer water is very effective in protecting the inner shell, in-covering will be better for the inner shell.
Sohn, Jung Woo; Jeon, Juncheol; Choi, Seung-Bok
2014-10-01
Vibration control performance of the ring-stiffened cylindrical shell structure is experimentally evaluated in this work. In order to achieve high control performance, advanced flexible piezoelectric actuator whose commercial name is Macro-Fiber Composite (MFC) is adapted to the shell structure. Governing equation is derived by finite element method and dynamic characteristics are investigated from the modal analysis results. Ring-stiffened cylindrical shell structure is then manufactured and modal test is conducted to verify modal analysis results. An optimal controller is designed and experimentally realized to the proposed shell structure system. Vibration control performance is experimentally evaluated in time domain and verified by simulated control results.
Qiu, Q.; Fang, Z. P.; Wan, H. C.; Zheng, L.
2013-07-01
Based on the Donnell assumptions and linear visco-elastic theory, the constitutive equations of the cylindrical shell with multilayer Passive Constrained Layer Damping (PCLD) treatments are described. The motion equations and boundary conditions are derived by Hamilton principle. After trigonometric series expansion and Laplace transform, the state vector is introduced and the dynamic equations in state space are established. The transfer function method is used to solve the state equation. The dynamic performance including the natural frequency, the loss factor and the frequency response of clamped-clamped multi-layer PCLD cylindrical shell is obtained. The results show that multi-layer PCLD cylindrical shell is more effective than the traditional three-layer PCLD cylindrical shell in suppressing vibration and noise if the same amount of material is applied. It demonstrates a potential application of multi-layer PCLD treatments in many critical structures such as cabins of aircrafts, hulls of submarines and bodies of rockets and missiles.
Cylindrical shed construction: the shell roof on the Jamin factory at Oosterhout, Netherlands
García García, Rafael; Valcarce Labrador, María Teresa
2009-01-01
The paper provides an overview of cylindrical shed reinforced concrete shells, a type of construction used primarily in industrial buildings. Like other types of shells, most cylindrical sheds were built between the end of World War II and the early nineteen sixties. The article reviews their characteristics and construction parameters based on contemporary studies and briefly documents some of the most prominent structures. The final chapter contains a detailed analysis of the design and con...
Influence of Transverse Shear on an Axial Crack in a Cylindrical Shell
DEFF Research Database (Denmark)
Krenk, Steen
1978-01-01
An axial crack in a cylindrical shell is investigated by use of a 10th order shell theory, which accounts for transverse shear deformations as well as a special kind of orthotropy. The symmetric problem is formulated in terms of two coupled singular integral equations, which are solved numerically....... The asymptotic membrane and bending stress fields ahead of the crack are found to be self similar. Stress intensity factors are given as a function of the shell parameter for various values of the ratio shell radius to shell thickness. Considerable differences from 8th order shell theory results are found...
Design aids for fixed support reinforced concrete cylindrical shells ...
African Journals Online (AJOL)
Shells are objects considered as materialization of the curved surface. Despite structural advantages and architectural aesthetics possessed by shells, relative degree of unacquaintance with shell behavior and design is high. Thin shells are examples of strength through form as opposed to strength through mass; their thin ...
Free and Forced Vibrations of Thick-Walled Anisotropic Cylindrical Shells
Marchuk, A. V.; Gnedash, S. V.; Levkovskii, S. A.
2017-03-01
Two approaches to studying the free and forced axisymmetric vibrations of cylindrical shell are proposed. They are based on the three-dimensional theory of elasticity and division of the original cylindrical shell with concentric cross-sectional circles into several coaxial cylindrical shells. One approach uses linear polynomials to approximate functions defined in plan and across the thickness. The other approach also uses linear polynomials to approximate functions defined in plan, but their variation with thickness is described by the analytical solution of a system of differential equations. Both approaches have approximation and arithmetic errors. When determining the natural frequencies by the semi-analytical finite-element method in combination with the divide and conqure method, it is convenient to find the initial frequencies by the finite-element method. The behavior of the shell during free and forced vibrations is analyzed in the case where the loading area is half the shell thickness
Lai, Changliang; Wang, Junbiao; Liu, Chuang
2014-10-01
Six typical composite grid cylindrical shells are constructed by superimposing three basic types of ribs. Then buckling behavior and structural efficiency of these shells are analyzed under axial compression, pure bending, torsion and transverse bending by finite element (FE) models. The FE models are created by a parametrical FE modeling approach that defines FE models with original natural twisted geometry and orients cross-sections of beam elements exactly. And the approach is parameterized and coded by Patran Command Language (PCL). The demonstrations of FE modeling indicate the program enables efficient generation of FE models and facilitates parametric studies and design of grid shells. Using the program, the effects of helical angles on the buckling behavior of six typical grid cylindrical shells are determined. The results of these studies indicate that the triangle grid and rotated triangle grid cylindrical shell are more efficient than others under axial compression and pure bending, whereas under torsion and transverse bending, the hexagon grid cylindrical shell is most efficient. Additionally, buckling mode shapes are compared and provide an understanding of composite grid cylindrical shells that is useful in preliminary design of such structures.
Vibration Analysis of Cylindrical Sandwich Aluminum Shell with Viscoelastic Damping Treatment
Directory of Open Access Journals (Sweden)
Tai-Hong Cheng
2013-01-01
Full Text Available This paper has applied the constrained viscoelastic layer damping treatments to a cylindrical aluminum shell using layerwise displacement theory. The transverse shear, the normal strains, and the curved geometry are exactly taken into account in the present layerwise shell model, which can depict the zig-zag in-plane and out-of-plane displacements. The damped natural frequencies, modal loss factors, and frequency response functions of cylindrical viscoelastic aluminum shells are compared with those of the base thick aluminum panel without a viscoelastic layer. The thickness and damping ratio of the viscoelastic damping layer, the curvature of proposed cylindrical aluminum structure, and placement of damping layer of the aluminum panel were investigated using frequency response function. The presented results show that the sandwiched viscoelastic damping layer can effectively suppress vibration of cylindrical aluminum structure.
Mercan, Kadir; Demir, Çiǧdem; Civalek, Ömer
2016-01-01
In the present manuscript, free vibration response of circular cylindrical shells with functionally graded material (FGM) is investigated. The method of discrete singular convolution (DSC) is used for numerical solution of the related governing equation of motion of FGM cylindrical shell. The constitutive relations are based on the Love's first approximation shell theory. The material properties are graded in the thickness direction according to a volume fraction power law indexes. Frequency values are calculated for different types of boundary conditions, material and geometric parameters. In general, close agreement between the obtained results and those of other researchers has been found.
Directory of Open Access Journals (Sweden)
Mercan Kadir
2016-01-01
Full Text Available In the present manuscript, free vibration response of circular cylindrical shells with functionally graded material (FGM is investigated. The method of discrete singular convolution (DSC is used for numerical solution of the related governing equation of motion of FGM cylindrical shell. The constitutive relations are based on the Love’s first approximation shell theory. The material properties are graded in the thickness direction according to a volume fraction power law indexes. Frequency values are calculated for different types of boundary conditions, material and geometric parameters. In general, close agreement between the obtained results and those of other researchers has been found.
Directory of Open Access Journals (Sweden)
S. Feroz
2008-12-01
Full Text Available An experimental study of mass transfer in forced convective flow of fluid electrolyte through submerged jets impinging normal to the target surface in a closed cylindrical cell in the presence of solids (Porcelain beads is reported. The pertinent dynamic and geometric variables of this study are flow rate, diameter of the nozzle, height of the nozzle from the target surface and solids fraction. The mass transfer measurements, made by the electrochemical method propose empirical correlations in the impingement and decreasing coefficient regions.
Dynamic Response of Shear-Flexible Cylindrical Isotropic Shells with Clamped Edges
Directory of Open Access Journals (Sweden)
Zafer I. Sakka
2006-01-01
Full Text Available It is fundamental to obtain the natural frequencies and the corresponding mode shapes for cylindrical shells in order to determine their response to different dynamic loading. In this paper an analytical investigation to the free vibration response of moderately-thick shear flexible isotropic cylindrical shells with all edges clamped is presented. The Sander’s kinematic relations for moderately thick cylindrical shell panels are utilized to develop the governing partial differential equations in conjunction with the boundary conditions. A recently developed generalized Navier’s approach, based on a boundary continuous double Fourier series expansion, is used as a solution methodology. A parametric study is presented with respect to various thicknesses, length and radius of curvature of the shell panel. The convergence of the solution method is established numerically for various parametric properties. The present results are compared with the results obtained from finite element method using a four-node isoparametric shell element. The results thus presented should serve as bench-mark solutions for future comparisons with numerical and approximate methods for calculation of free vibration parameters of moderately-thick isotropic cylindrical shells.
Directory of Open Access Journals (Sweden)
Dong Tang
2016-03-01
Full Text Available This article is concerned with free vibration analysis of open circular cylindrical shells with either the two straight edges or the two curved edges simply supported and the remaining two edges supported by arbitrary classical boundary conditions. An analytical solution of the traveling wave form along the simply supported edges and the standing wave form along the remaining two edges is obtained based on the Flügge thin shell theory. With such a unidirectional traveling wave form solution, the method of reverberation-ray matrix is introduced to derive the equation of natural frequencies of the open circular cylindrical shell with various boundary conditions. Then, the golden section search algorithm is employed to obtain the natural frequencies of the open circular cylindrical shell. The calculation results are compared with those obtained by the finite element method and the method in available literature. Finally, the natural frequencies of the open circular cylindrical shell with various boundary conditions are calculated and the effects of boundary conditions on the natural frequencies are examined. The calculation results can be used as benchmark values for researchers to check their numerical methods and for engineers to design thin structures with shell components.
Acoustic radiation of damped cylindrical shell with arbitrary thickness in the fluid field
Zhang, Jun-Jie; Li, Tian-Yun; Ye, Wen-Bing; Zhu, Xiang
2010-12-01
The insertion loss of acoustic radiation of damped cylindrical shell described by 3-D elasticity Navier equations under radial harmonic applied load in fluid is presented. The classical integral transform technique, potential theory and Lamè resolution are used to derive the solutions of Navier equations. The higher precision inversion computation is introduced to solve the linear equations. Comparing with acoustic radiation of one-layer cylindrical shell, the influence of thickness, mass density, dilatational wave loss factor and Young's modulus of damping material and circumferential mode number of the cylindrical shell on the insertion loss is concluded. The theoretical model in the paper can be used to deal with the arbitrary thickness and any frequency of the coated layer in dynamic problem. The conclusions may be of theoretical reference to the application of damping material to noise and vibration control of submarines and underwater pipes.
Subwavelength core/shell cylindrical nanostructures for novel plasmonic and metamaterial devices
Kim, Kyoung-Ho; No, You-Shin
2017-12-01
In this review, we introduce novel plasmonic and metamaterial devices based on one-dimensional subwavelength nanostructures with cylindrical symmetry. Individual single devices with semiconductor/metal core/shell or dielectric/metal core/multi-shell structures experience strong light-matter interaction and yield unique optical properties with a variety of functions, e.g., invisibility cloaking, super-scattering/super-absorption, enhanced luminescence and nonlinear optical activities, and deep subwavelength-scale optical waveguiding. We describe the rational design of core/shell cylindrical nanostructures and the proper choice of appropriate constituent materials, which allow the efficient manipulation of electromagnetic waves and help to overcome the limitations of conventional homogeneous nanostructures. The recent developments of bottom-up synthesis combined with the top-down fabrication technologies for the practical applications and the experimental realizations of 1D subwavelength core/shell nanostructure devices are briefly discussed.
Iakovlev, S.; Dooley, G.; Williston, K.; Gaudet, J.
2011-12-01
Several most important features of the hydrodynamic field induced inside a circular cylindrical shell filled with and submerged into different fluids when it is subjected to an external shock wave are considered. This investigation is a follow-up of an earlier study of the two-fluid shell-shock interaction [S. Iakovlev, Interaction between an external shock wave and a cylindrical shell filled with and submerged into different fluids, Journal of Sound and Vibration 322 (2009) 401-437], and it addresses a number of practically important issues not covered in that work. The focus of this study is on the evolution of the respective hydrodynamic patterns in response to the continuous change of the parameters of the fluids, in particular the speed of sound. Along with the analysis of the hydrodynamic patterns it is also demonstrated that when one is concerned with the highest pressure attained inside the shell, the most dangerous combination of the parameters occurs when the ratio of the internal and external acoustic speeds is close to 0.48, with the respective pressure exceeding the maximum incident pressure by more than 110 percent. The effect that the hydrodynamic features discussed have on the stress state of the shell is addressed as well, and it is observed that the maximum tensile stress is significantly affected by the evolution of the considered hydrodynamic features, whereas the maximum compressive stress is not. It is also observed that the maximum tensile stress is very sensitive to the change of the ratio of the acoustic speeds in the internal and external fluids, with as little an increase of the latter as 13 percent resulting in more than doubling of the former in some cases.
Directory of Open Access Journals (Sweden)
Michelle S. Hoo Fatt
1996-01-01
Full Text Available A theoretical approach was developed for predicting the plastic deformation of a cylindrical shell subject to asymmetric dynamic loads. The plastic deformation of the leading generator of the shell is found by solving for the transverse deflections of a rigid-plastic beam/string-on-foundation. The axial bending moment and tensile force in the beam/string are equivalent to the longitudinal bending moments and membrane forces of the shell, while the plastic foundation force is equivalent to the shell circumferential bending moment and membrane resistances. Closed-form solutions for the transient and final deformation profile of an impulsive loaded shell when it is in a “string” state were derived using the eigenfunction expansion method. These results were compared to DYNA 3D predictions. The analytical predictions of the transient shell and final centerline deflections were within 25% of the DYNA 3D results.
Liu, Chun-Chuan; Li, Feng-Ming; Chen, Zhao-Bo; Yue, Hong-Hao
2013-02-01
The method of reverberation ray matrix is extended to investigate the transient wave propagation and early short time transient responses of the ring stiffened laminated composite cylindrical shells subjected to impact loads. The ring stiffened laminated cylindrical shells are modeled as the continuous coupling systems between the vibration of the un-stiffened laminated cylindrical shell and the motion of the curved beams. The dynamic models of the laminated cylindrical shell and curved beams in the Laplace phase space are established on the basis of the first order shear deformation theory. The reverberation ray matrix can be determined by the boundary and continuous conditions of the ring stiffened laminated cylindrical shell. Using the fast Fourier transform algorithm, the dynamic responses of the ring stiffened laminated cylindrical shells can be computed. Through the numerical simulations, it can be seen that the early short time transient accelerations of the ring stiffened laminated cylindrical shells under impact loads are very large, while the early short time transient shear strains and displacements are very small. Furthermore, the influences of the ring stiffener number and impact load types on the early short time transient responses of the ring stiffened laminated cylindrical shells are also investigated.
Harmonic vibrations and waves in a cylindrical helically anisotropic shell
Panfilov, I. A.; Ustinov, Yu. A.
2012-04-01
A Kirchhoff-Love type applied theory is used to study the specific characteristics of harmonic waves and vibrations of a helically anisotropic shell. Special attention is paid to axisymmetric and bending vibrations. In both cases, the dispersion equations are constructed and a qualitative and numerical analysis of their roots and the corresponding elementary solutions is performed. It is shown that the skew anisotropy in the axisymmetric case generates a relation between the longitudinal and torsional vibrations which is mathematically described by the amplitude coefficients of homogeneous waves. In the case of a shell with rigidly fixed end surfaces, the dependence of the first two natural frequencies on the shell length and the helical line slope α, i.e., the geometric parameter of helical anisotropy, is studied. A boundary value problem in which longitudinal vibrations are generated on one of the end surfaces and the other end is free of forces and moments is considered to analyze the degree of transformation of longitudinal vibrations into longitudinally torsional vibrations. In the case of bending vibrations, two problems for a half-infinite shell are studied as well. In the first problem, the waves are excited kinematically by generating harmonic vibrations of the shell end surface in the plane of the axial cross-section, and it is shown that the axis generally moves in some closed trajectories far from the end surface. In the second problem, the reflection of a homogeneous wave incident on the shell end is examined. It is shown that the "boundary resonance" phenomenon can arise in some cases.
Acoustic Radiation from Single and Double Ribbed Circular Cylindrical Shells.
1984-03-30
Repeatability of Acoustic Radiation Measurements - Single Shell with T- haker Vertical ( =00), Single Radial Drive in Middle of Shell and Phone No. 1...LAYER 0 ~10 U LUU ~-40 -50 0 2-34 FRQENY(kz Fiue3. FreLvlItDieShkrwt n ihu trfa LL.l 0’ Lave -- oube Shll ith hakers orA and inge RaialDr,-.-eon he Ji...FORCE IN SHAKER NO.I ’ HAKER LOCATION - ON THE JOINT B,%ND LONG. DRIVE - OUT OF PH AS E IS THIS THE CORRECT HEADER INFO? Y NORMALIZATION MENU
Dynamic Analysis of a non-linear vibrating circular cylindrical shell ...
African Journals Online (AJOL)
We investigated in this paper the effect of non-linear vibration of a circular cylindrical shell subject to axially symmetric loading. We consider the approximation of the equation using the regular perturbation technique and thereby solving the resulting linear equation analytically. The result indicates an exponential decay ...
Buckling tests of sandwich cylindrical shells with and without cut-outs
Bisagni, C.; Davidson, B.D.; Czabaj, M.W.; Ratcliffe, J.G.
2016-01-01
The results of buckling tests performed during the project DESICOS funded by the European Commission in the FP7 Programme are here presented. The tested structures are sandwich cylindrical shells that consist of reduced models of a component of the Ariane 5 launcher: the Dual Launch System. In
Vibroacoustic Response of a Double-Walled Cylindrical FGM Shell with a Porous Sandwiched Layer
Ramezani, H.; Talebitooti, R.
2015-11-01
The transmission loss of sound through a cylindrical structure whose walls sandwich a layer of porous material is predicted on the basis of the classical shell theory for shells made of functionally graded materials (FGMs). FGM shells composed of metal and ceramic, with three different distributions (power-law, sigmoid, or exponential) of their volume fractions across the wall thickness, are considered. The porous layer is modeled as a fluid with equivalent properties. The transmission loss through the multilayered structure is obtained analytically in a broad frequency band. To validate the results found, they are compared with some known ones. The effects of variation in the volume fractions of materials are also studied.
Effectiveness of the magnetostatic shielding by the cylindrical shells
Energy Technology Data Exchange (ETDEWEB)
Grabchikov, S.S.; Trukhanov, A.V. [SSPA “Scientific and practical materials research centre of NAS of Belarus”, 19 P. Brovki Str., 220072 Minsk (Belarus); Trukhanov, S.V., E-mail: truhanov@ifttp.bas-net.by [SSPA “Scientific and practical materials research centre of NAS of Belarus”, 19 P. Brovki Str., 220072 Minsk (Belarus); Kazakevich, I.S.; Solobay, A.A. [SSPA “Scientific and practical materials research centre of NAS of Belarus”, 19 P. Brovki Str., 220072 Minsk (Belarus); Erofeenko, V.T. [BSU Institution ' Scientific Research Institute of Applied Problems of Mathematics and Informatics ' , av. Nezavisimosti 4 – 702, 220030 Minsk (Belarus); Vasilenkov, N.A. [CJSC ' TESTPRIBOR' , st. Svobody, 31-1, 125362 Moscow (Russian Federation); Volkova, O.S. [Low temperatures physics and superconductivity department, MSU named after M.V. Lomonosov, Moscow (Russian Federation); National University of Science and Technology MISiS, 119049, Moscow, Leninsky Prospekt, 4 (Russian Federation); Shakin, A. [National University of Science and Technology MISiS, 119049, Moscow, Leninsky Prospekt, 4 (Russian Federation)
2016-01-15
The experimental research of the magnetostatic shielding effectiveness and the analytical calculations of the average magnetic permeability of single-layer cylindrical sample of the shields based on electrolytically deposited Ni{sub 80}Fe{sub 20} alloy are carried out. The locations of maxima on the Ef(H) and μ(H) curves do not match each other, which is difficult to interpret in terms of the shunting model. The results are explained by the non-linear distribution of the magnetic permeability through the thickness of the shield. It has been shown that in the magnetic fields range from 100 A/m up to 2700 A/m, the shields based on the Ni{sub 80}Fe{sub 20} alloy are preferred over ones based on the 84KHSR amorphous ribbon. It is concluded that at the selection of shield materials it should take into account not only the main magnetic characteristics – μ; H{sub s}; H{sub c} but also H{sub max} parameter, which is important to evaluate the effectiveness of magnetic shielding. - Highlights: • One-layer cylindrical shields based on electrodeposited Ni{sub 80}Fe{sub 20} alloy are obtained. • Magnetostatic shielding effectiveness is experimentally investigated. • Calculations of the average magnetic permeability are carried out. • Results are explained by the non-linear distribution of the magnetic permeability. • Parameters important for the magnetic shielding effectiveness are indicated.
Wave based analysis of the Green's function for a layered cylindrical shell.
Magliula, Elizabeth A; McDaniel, J Gregory
2012-07-01
Cylindrical shells composed of concentric layers may be designed to affect the way that elastic waves are generated and propagated, particularly when some layers are anisotropic. To aid the design process, the present work develops a wave based analysis of the Green's function for a layered cylindrical shell in which the response is given as a sum of waves propagating in the axial coordinate. The analysis assumes linear Hookean materials for each layer. It uses finite element discretizations in the radial coordinate and Fourier series expansions in the circumferential coordinate, leading to linear equations in the axial wavenumber domain that relate shell displacements and forces. Inversion to the axial domain is accomplished via a state-space formulation that is evaluated using residue integration. The resulting expression for the Green's function for each circumferential harmonic is a summation over the natural waves of the shell. The finite element discretization in the radial direction allows the approach to be used for arbitrarily thick shells. The approach is benchmarked to results from an isotropic shell and numerical examples are given for a shell composed of a fiber-reinforced material. The numerical examples illustrate the effect of fiber orientation on the Green's function.
Effect of damage on the modal parameters of a cylindrical shell
Energy Technology Data Exchange (ETDEWEB)
Srinivasan, M.G.; Kot, C.A.
1992-01-01
The objective of the study was to investigate the feasibility of assessing damage to structural systems by measuring the changes in the dynamic characteristics of a thin circular cylindrical shell with both ends open. Theoretical and experimental modal analyses were performed for the shell. Subsequently, a notch was machined into the shell simulating a small amount of damage. The shell with the notch was again subjected to experimental modal analysis. A comparison of the modal parameters determined from the tests before and after the shell was damaged showed that the natural frequencies were not sensitive to the crack introduced. However, some of the mode shapes showed significant changes, establishing that the mode shapes were the more sensitive parameters for damage detection.
Effect of damage on the modal parameters of a cylindrical shell
Energy Technology Data Exchange (ETDEWEB)
Srinivasan, M.G.; Kot, C.A.
1992-02-01
The objective of the study was to investigate the feasibility of assessing damage to structural systems by measuring the changes in the dynamic characteristics of a thin circular cylindrical shell with both ends open. Theoretical and experimental modal analyses were performed for the shell. Subsequently, a notch was machined into the shell simulating a small amount of damage. The shell with the notch was again subjected to experimental modal analysis. A comparison of the modal parameters determined from the tests before and after the shell was damaged showed that the natural frequencies were not sensitive to the crack introduced. However, some of the mode shapes showed significant changes, establishing that the mode shapes were the more sensitive parameters for damage detection.
Dispersion of axially symmetric waves in fluid-filled cylindrical shells
DEFF Research Database (Denmark)
Bao, X.L.; Überall, H.; Raju, P. K.
2000-01-01
Acoustic waves normally incident on an elastic cylindrical shell can cause the excitation of circumferential elastic waves on the shell. These shells may be empty and fluid immersed, or fluid filled in an ambient medium of air, or doubly fluid loaded inside and out. Circumferential waves......, 317 (1972)]. We have extended the work of Kumar to the case of fluid-filled aluminum shells and steel shells imbedded in air. These cases demonstrate the existence of circumferential waves traveling in the filler fluid, exhibiting a certain simplicity of the dispersion curves of these waves....... This is in striking contrast to the results for double (outside and inside) loading by two fluids of comparable density, where circumferential waves in both external and internal fluids were found, their interaction causing segmentation and repulsion phenomena of their dispersion curves. The condition of standing...
Study of the vibration of bulkhead-stiffened cylindrical shells by laser-based methods
Zhu, Ninghui
The first part of this dissertation work deals with an experimental study of the vibration behavior of bulkhead stiffened cylindrical shells by using laser-based vibration measurement methods. Holographic interferometry and laser speckle photography are first demonstrated on revealing the dynamic behavior of a 22 ft long cylindrical shell. These methods are thereafter further explored to study the vibration characteristic of cylindrical shells with different stiffeners such as a full bulkhead or a partial bulkhead. Many experimentally obtained holograms and specklegrams reveal interesting features of the vibration of bulkhead stiffened cylindrical shells. The experimentally obtained results are compared with those obtained from a finite element model developed by General Dynamic Electric Boat Division, and the finite element model is generally validated. Mode localization theory is used to explain some interesting findings in experiments and the reason of some discrepancies between the finite element analysis and experiment results. The presence of irregularities in a weakly coupled structure such as a bulkhead-stiffened cylindrical shell is shown to be able to localize the modes of vibration and inhibit the propagation of vibration within the shell. A numerical simulation based on the finite element modal analysis indicates the validation of this explanation of the experimental findings. Thereafter, the eigensolutions of disordered, plate-stiffened cylindrical shell stiffened are derived by the use of receptance method. Numerical calculations are thereafter performed based upon this model and indeed reveal the exist of localized vibration in this kind of structure. This analytical study provides physical insights into the mode localization phenomenon in stiffened cylindrical shell type of structures from a more systematic manner. The conditions and the effect of mode localization on natural frequencies and mode shapes of cylindrical shell structure are also
Analysis of the external radiation from circular cylindrical shells
Aslani, Pegah; Sommerfeldt, Scott D.; Blotter, Jonathan D.
2017-11-01
Structurally radiated sound power is a critical design parameter. The acoustic radiation mode approach for computing sound power was developed in the early 1990s and has since been widely used. It has been shown to be a rather efficient approach for determining the radiated sound power. In previous research, radiation mode expressions have been developed for planar and spherical structures, as well as axisymmetric modes of internal and external radiation from cylinders. In this work, the radiation modes for external radiating cylinders which account for both axial and circumferential dependence are presented. The expressions are uniquely developed using cylindrical basis functions which are a more natural match to the geometry than past developments, which have been based on spherical harmonics. Higher order radiation modes than have been previously presented are shown. The ;leapfrog effect;, whereby higher order modes leapfrog over lower modes in terms of their radiation efficiencies as the frequency goes above the cut-on frequency for those modes, is discussed in detail. The relationships between the mode efficiency and the coincidence effect associated with the cut-on frequencies of the vibration modes are described.
Li, Yuyin; Zhang, Yahui; Kennedy, David
2017-10-01
A random vibration analysis of an axially compressed cylindrical shell under a turbulent boundary layer (TBL) is presented in the symplectic duality system. By expressing the cross power spectral density (PSD) of the TBL as a Fourier series in the axial and circumferential directions, the problem of structures excited by a random distributed pressure due to the TBL is reduced to solving the harmonic response function, which is the response of structures to a spatial and temporal harmonic pressure of unit magnitude. The governing differential equations of the axially compressed cylindrical shell are derived in the symplectic duality system, and then a symplectic eigenproblem is formed by using the method of separation of variables. Expanding the excitation vector and unknown state vector in symplectic space, decoupled governing equations are derived, and then the analytical solution can be obtained. In contrast to the modal decomposition method (MDM), the present method is formulated in the symplectic duality system and does not need modal truncation, and hence the computations are of high precision and efficiency. In numerical examples, harmonic response functions for the axially compressed cylindrical shell are studied, and a comparison is made with the MDM to verify the present method. Then, the random responses of the shell to the TBL are obtained by the present method, and the convergence problems induced by Fourier series expansion are discussed. Finally, influences of the axial compression on random responses are investigated.
Cylindrical Shells Made of Stainless Steel - Investigation of Postbuckling
Stehr, Sebastian; Stranghöner, Natalie
2017-06-01
The relevant load case of open thin-walled shells is often wind loading during construction. Because of the missing stabilization effect of the roof they show a very high sensitivity to buckling which results into higher wall thicknesses. As part of the European RFCS research project BiogaSS the Institute for Metal and Lightweight Structures of the University of Duisburg-Essen carried out investigations on open thin-walled tanks made of austenitic and duplex stainless steels under wind load to study a possible economic advantage which might be gained from the consideration of the elastic postbuckling behaviour. This contribution presents not only experimental and numerical results but also first recommendations regarding the range of possible buckling reduction factors which might be incorporated in future revisions of EN 1993-1-6 and EN 1993-4-2.
Free Vibration Characteristics of Cylindrical Shells Using a Wave Propagation Method
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A. Ghoshal
2001-01-01
Full Text Available In the present paper, concept of a periodic structure is used to study the characteristics of the natural frequencies of a complete unstiffened cylindrical shell. A segment of the shell between two consecutive nodal points is chosen to be a periodic structural element. The present effort is to modify Mead and Bardell's approach to study the free vibration characteristics of unstiffened cylindrical shell. The Love-Timoshenko formulation for the strain energy is used in conjunction with Hamilton's principle to compute the natural propagation constants for two shell geometries and different circumferential nodal patterns employing Floquet's principle. The natural frequencies were obtained using Sengupta's method and were compared with those obtained from classical Arnold-Warburton's method. The results from the wave propagation method were found to compare identically with the classical methods, since both the methods lead to the exact solution of the same problem. Thus consideration of the shell segment between two consecutive nodal points as a periodic structure is validated. The variations of the phase constants at the lower bounding frequency for the first propagation band for different nodal patterns have been computed. The method is highly computationally efficient.
Experiment and Simulation Analysis on Noise Attenuation of Al/MF Cylindrical Shells
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Bin Li
2017-01-01
Full Text Available For the issue concerning internal noise reduction of Al-made cylindrical shell structure, the noise control method of laying melamine foam (MF layer is adopted for in-shell noise attenuation experiments of Al and Al/MF cylindrical shells and corresponding internal noise response spectrograms are obtained. Based on the Virtual.Lab acoustics software, a finite element model is established for the analysis of noise in the Al/MF cylinder shell and numerical simulation computation is conducted for the acoustic mode and in-shell acoustic response; the correctness of the finite element model is verified via comparison with measured data. On this basis, influence rules of different MF laying rate and different laying thickness on acoustic cavity resonance response within the low and medium frequency range of 100–400 Hz are studied. It is indicated that noise reduction increases with MF laying rate, but the amplification decreases along with the rising of MF laying rate; noise reduction per unit thickness decreases with the increase of laying thickness, while noise reduction per unit area increases.
Analyses of a Dipole Antenna Loaded by a Cylindrical Shell of Double Negative (DNG Metamaterial
Directory of Open Access Journals (Sweden)
Khan M. Z. Shams
2007-01-01
Full Text Available The current distribution, input impedance, and radiation pattern of a cylindrical dipole antenna enclosed by a thin cylindrical shell of double negative (DNG metamaterial are computed using the piecewise sinusoidal Galerkin formulation. In the presence of the DNG shell, the dipole antenna exhibits three interesting characteristics. The input impedance shows potentials for wide bandwidth due to the relative insensitivity of the impedance with frequency. Within specific ranges of DNG material parameter values, the dipole shows resonance at much lower frequencies than its resonant frequency in free space. The dipole does not show change in the direction of the principal beam nor does it show signs of beam splitting and side lobes even when the antenna length approaches one and a half wavelength.
Bi-orthogonality conditions for power flow analysis in fluid-loaded elastic cylindrical shells
DEFF Research Database (Denmark)
Ledet, Lasse; Sorokin, Sergey V.; Larsen, Jan Balle
2015-01-01
The paper addresses the classical problem of time-harmonic forced vibrations of a fluid-loaded cylindrical shell considered as a multi-modal waveguide carrying infinitely many waves. Firstly, a modal method for formulation of Green’s matrix is derived by means of modal decomposition. The method...... builds on the recent advances on bi-orthogonality conditions for multi-modal waveguides, which are derived here for an elastic fluid-filled cylindrical shell. Subsequently, modal decomposition is applied to the bi-orthogonality conditions to formulate explicit algebraic equations to express the modal...... vibro-acoustic waveguide is subjected to separate pressure and velocity acoustical excitations. Further, it has been found and justified that the bi-orthogonality conditions can be used as a ’root finder’ to solve the dispersion equation. Finally, it is discussed how to predict the response of a fluid...
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LI Ruibiao
2017-08-01
Full Text Available Aiming at the problem of frequent abnormal outboard noise in ships, an abnormal noise source location method is proposed, and a location model checked by the double cylindrical shell experiment is built. The model calculates the coordinates through the improved hyperbolic positioning method on the basis of the traditional hyperbolic positioning method, with the time-delay estimation by the generalized cross-correlation method as the input. In the process of the experiment, the outboard abnormal noise source is simulated by the percussion, comparing the positioning accuracy of the two methods and analyzing the influence of time-delay estimation on positioning accuracy. The results show that the hyperbolic positioning method based on double cylindrical shell can accurately locate the coordinates of abnormal noise sources, and is feasible for the abnormal outboard noise source positioning of ships. In addition, the method can provide theoretical guidance for the location of abnormal outboard noise sources.
Analysis of Experimental Research on Cyclones with Cylindrical and Spiral Shells
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Aleksandras Chlebnikovas
2012-12-01
Full Text Available The conducted investigation is aimed at providing information on air flow parameters in the cylindrical and spiral shell (devices are designed for separating solid particles from air flow having tangent flow inlet. Experimental research has employed multi-cyclones created by the Department of Environmental Protection at Vilnius Gediminas Technical University. The study is focused on investigating and comparing the distribution of the dynamic pressure of the airflow in six-channel cyclones inside the structures of devices. The paper establishes and estimates the efficiency of air cleaning changing air phase parameters using different particulate matters. The efficiency of the cyclone has been defined applying the weighted method based on LAND 28-98/M-08 methodology. The article presents the results of experimental research on the air cleaning efficiency of cylindrical and spiral shells using 20 µm glass and clay particulate matter under the initial concentration that may vary from 500 mg/m3 to 15 g/m3 using semi-rings with windows at different positions. The obtained results has shown that the maximum efficiency of the cylindrical shell increases up to 87,3 % while the initial concentration of glass makes 15 g/m3.Article in Lithuanian
Dynamic reponse of a cylindrical shell immersed in a potential fluid
Energy Technology Data Exchange (ETDEWEB)
Cummings, G.E.
1978-04-18
A numerical solution technique is presented for determining the dynamic response of a thin, elastic, circular, cylindrical shell of constant wall thickness and density, immersed in a potential fluid. The shell may be excited by an arbitrary radial forcing function with a specified time history and spatial distribution. In addition, a pressure history may be specified over a segment of the fluid outer boundary. Any of the natural shell end conditions may be prescribed. A numerical instability prevented direct solutions where the ratio of the hydrodynamic forces to shell inertial forces is greater than two. This instability is believed to be the result of the weak coupling between the equations describing the fluid to those describing the shell. To circumvent this instability, an effective mass was calculated and added to the shell. Comparison of numerical to experimental results are made using a /sup 1///sub 12/ scale model of a nuclear reactor core support barrel. Natural frequencies and modes are determined for this model in air, water, and oil. The computed frequencies compare to experimental results to within 15%. The use of this numerical technique is illustrated by comparing it to an analytical solution for shell beam modes and an uncertainty in the analytical technique concerning the proper effective mass to use, is resolved.
Stability and acoustic scattering in a cylindrical thin shell containing compressible mean flow
Brambley, E. J.; Peake, N.
We consider the stability of small perturbations to a uniform inviscid compressible flow within a cylindrical linear-elastic thin shell. The thin shell is modelled using FlBers criterion, and the system is found to be either stable or absolutely unstable, with absolute instability occurring for sufficiently small shell thicknesses. This is significantly different from the stability of a thin shell containing incompressible fluid, even for parameters for which the fluid would otherwise be expected to behave incompressibly (for example, water within a steel thin shell). Asymptotic expressions are derived for the shell thickness separating stable and unstable behaviour.We then consider the scattering of waves by a sudden change in the duct boundary from rigid to thin shell, using the Wienerspringspring-damper model. The scattering results derived here are exact, unique and causal, without the need to apply a Kutta-like condition or to include an instability wave. A movie is available with the online version of the paper.
Tang, Yvette Y.; Silcox, Richard J.; Robinson, Jay H.
1996-01-01
This paper examines sound transmission into two concentric cylindrical sandwich shells subject to turbulent flow on the exterior surface of the outer shell. The interior of the shells is filled with fluid medium and there is an airgap between the shells in the annular space. The description of the pressure field is based on the cross-spectral density formulation of Corcos, Maestrello, and Efimtsov models of the turbulent boundary layer. The classical thin shell theory and the first-order shear deformation theory are applied for the inner and outer shells, respectively. Modal expansion and the Galerkin approach are used to obtain closed-form solutions for the shell displacements and the radiation and transmission pressures in the cavities including both the annular space and the interior. The average spectral density of the structural responses and the transmitted interior pressures are expressed explicitly in terms of the summation of the cross-spectral density of generalized force induced by the boundary layer turbulence. The effects of acoustic and hydrodynamic coincidences on the spectral density are observed. Numerical examples are presented to illustrate the method for both subsonic and supersonic flows.
Calculation and design of lattice cylindrical shells manufactured of unidirectional CFRPs
Golushko, S.; Semisalov, B.
2017-10-01
The work is devoted to numerical simulation of the stationary stress-strain state of lattice cylindrical shells made of unidirectional carbon fiber reinforced plastics and to their optimal design. After averaging stiffness characteristics of lattice structure, the displacement and stress formulations for continuum anisotropic equivalents of lattice shells are given on the basis of classical relations of 3D theory of elasticity. While using a special fast pseudo-spectral algorithm, the solutions to problems of axial compression of anisogrid shells are obtained and compared one to another. The algorithm provides exponential decrease of error of approximation and requires small computational resources. Using this algorithm we have found the optimal geometrical parameters of structure ensuring its bearing capacity under given non-uniform loads.
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Ali Nouri
2014-01-01
Full Text Available The maximizing of sound transmission loss (TL across a functionally graded material (FGM cylindrical shell has been conducted using a genetic algorithm (GA. To prevent the softening effect from occurring due to optimization, the objective function is modified based on the first resonant frequency. Optimization is performed over the frequency range 1000–4000 Hz, where the ear is the most sensitive. The weighting constants are chosen here to correspond to an A-weighting scale. Since the weight of the shell structure is an important concern in most applications, the weight of the optimized structure is constrained. Several traditional materials are used and the result shows that optimized shells with aluminum-nickel and aluminum-steel FGM are the most effective at maximizing TL at both stiffness and mass control region, while they have minimum weight.
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Gangolu Vijay Kumar
2012-01-01
Full Text Available A four-node composite facet-shell element is developed, accounting for electromechanical coupling of Macrofiber Composite (MFC and conventional PZT patches. Further a warping correction is included in order to capture correctly the induced strain of conformable MFC, surface bonded on a cylindrical shell. The element performance to model the relations between in-plane electric field to normal strains is examined with the help of experiment and ANSYS analysis. In ANSYS, a simple modeling scheme is proposed for MFC using a parallel capacitors concept. The independent modal space control technique has been revisited to address the control of combination resonances through a selective modal space control scheme, where two or more modes can be combined to form the vibrating system or plant in modal domain. The developed control schemes are implemented in a digital processor using DS1104 and the closed-loop vibration control experiments are conducted on a CFRP shell structure. The influence of directionally induced actuation of MFC actuators on elastic couplings of composite shell is studied theoretically and is subsequently demonstrated in experiments. MFC actuators provide the much needed optimization domain for achieving the vibration control of combination resonances of elastically coupled deep-shell structure.
Ni, Peiyuan; Ersson, Mikael; Jonsson, Lage Tord Ingemar; Jönsson, Pär Göran
2017-12-01
Different sizes and shapes of nonmetallic inclusions in a swirling flow submerged entry nozzle (SEN) placed in a new tundish design were investigated by using a Lagrangian particle tracking scheme. The results show that inclusions in the current cylindrical tundish have difficulties remaining in the top tundish region, since a strong rotational steel flow exists in this region. This high rotational flow of 0.7 m/s provides the required momentum for the formation of a strong swirling flow inside the SEN. The results show that inclusions larger than 40 µm were found to deposit to a smaller extent on the SEN wall compared to smaller inclusions. The reason is that these large inclusions have Separation number values larger than 1. Thus, the swirling flow causes these large size inclusions to move toward the SEN center. For the nonspherical inclusions, large size inclusions were found to be deposited on the SEN wall to a larger extent, compared to spherical inclusions. More specifically, the difference of the deposited inclusion number is around 27 pct. Overall, it was found that the swirling flow contains three regions, namely, the isotropic core region, the anisotropic turbulence region and the near-wall region. Therefore, anisotropic turbulent fluctuations should be taken into account when the inclusion motion was tracked in this complex flow. In addition, many inclusions were found to deposit at the SEN inlet region. The plotted velocity distribution shows that the inlet flow is very chaotic. A high turbulent kinetic energy value of around 0.08 m2/s2 exists in this region, and a recirculating flow was also found here. These flow characteristics are harmful since they increase the inclusion transport toward the wall. Therefore, a new design of the SEN inlet should be developed in the future, with the aim to modify the inlet flow so that the inclusion deposition is reduced.
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V. S. Zarubin
2015-01-01
Full Text Available Liquid hydrogen and oxygen are used as the oxidizer and fuel for liquid rocket engines. Liquefied natural gas, which is based on methane, is seen as a promising motor fuel for internal combustion engines. One of the technical problems arising from the use of said cryogenic liquid is to provide containers for storage, transport and use in the propulsion system. In the design and operation of such vessels it is necessary to have reliable information about their temperature condition, on which depend the loss of cryogenic fluids due to evaporation and the stress-strain state of the structural elements of the containers.Uneven temperature distribution along the generatrix of the cylindrical thin-walled shell of rocket cryogenic tanks, in a localized zone of cryogenic liquid level leads to a curvature of the shell and reduce the permissible axle load in a hazard shell buckling in the preparation for the start of the missile in flight with an increasing acceleration. Moving the level of the cryogenic liquid during filling or emptying the tank at a certain combination of parameters results in an increase of the local temperature distribution nonuniformity.Along with experimental study of the shell temperature state of the cryogenic container, methods of mathematical modeling allow to have information needed for designing and testing the construction of cryogenic tanks. In this study a mathematical model is built taking into account features of heat transfer in a cryogenic container, including the boiling cryogenic liquid in the inner surface of the container. This mathematical model describes the temperature state of the thin-walled shell of cylindrical cryogenic tank during filling and emptying. The work also presents a quantitative analysis of this model in case of fixed liquid level, its movement at a constant speed, and harmonic oscillations relative to a middle position. The quantitative analysis of this model has allowed to find the limit options
Stability of cylindrical shell panels of modern materials under dynamic loading
Semenov, A. A.
2017-12-01
Orthotropic cylindrical shell panels under dynamic loading (the load has a linear time dependency) are examined in this paper. Relationships of a mathematical model of their deformation are presented in view of the geometric nonlinearity, transverse shears and orthotropy of the material. The Kantorovich method is applied to form a system of ordinary differential equations. The derived system is solved by the Rosenbrock method. The stability of several types of orthotropic panels of modern materials (fiberglass, carbon fiber reinforced plastic, etc.) is studied and critical load values are obtained.
Stability analysis of an open shallow cylindrical shell with imperfection under external pressure
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Psotny Martin
2017-01-01
Full Text Available Elastic shallow generalized cylindrical shells of an open cross-section subjected to the various forms of external pressure are analysed in the paper numerically using the finite element method. Load - displacement paths are calculated for the perfect and imperfect geometry, respectively. Special attention is paid to the influence of initial geometric imperfection on the limit load level of fundamental equilibrium path of nonlinear analysis. ANSYS system was used for analysis, arc-length method was chosen for obtaining fundamental load - displacement path of solution.
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K. Ramajeyathilagam
2001-01-01
Full Text Available Experimental and numerical investigations on cylindrical shell panels subjected to underwater explosion loading are presented. Experiments were conducted on panels of size 0.8 × 0.6 × 0.00314 m and shell rise-to-span ratios h/l = 0.0, 0.05, 0.1 , using a box model set-up under air backed conditions in a shock tank. Small charges of PEK I explosive were employed. The plastic deformation of the panels was measured for three loading conditions. Finite element analysis was carried out using the CSA/GENSA [DYNA3D] software to predict the plastic deformation for various loading conditions. The analysis included material and geometric non-linearities, with strain rate effects incorporated based on the Cowper-Symonds relation. The numerical results for plastic deformation are compared with those from experiments.
Ray and wave scattering in smoothly curved thin shell cylindrical ridges
Sondergaard, Niels
2016-01-01
We propose wave and ray approaches for modelling mid- and high- frequency structural vibrations through smoothed joints on thin shell cylindrical ridges. The models both emerge from a simplified classical shell theory setting. The ray model is analysed via an appropriate phase-plane analysis, from which the fixed points can be interpreted in terms of the reflection and transmission properties. The corresponding full wave scattering model is studied using the finite difference method to investigate the scattering properties of an incident plane wave. Through both models we uncover the scattering properties of smoothed joints in the interesting mid-frequency region close to the ring frequency, where there is a qualitative change in the dynamics from anisotropic to simple geodesic propagation.
Realization of low-scattering metamaterial shell based on cylindrical wave expanding theory.
Wu, Xiaoyu; Hu, Chenggang; Wang, Min; Pu, Mingbo; Luo, Xiangang
2015-04-20
In this paper, we demonstrate the design of a low-scattering metamaterial shell with strong backward scattering reduction and a wide bandwidth at microwave frequencies. Low echo is achieved through cylindrical wave expanding theory, and such shell only contains one metamaterial layer with simultaneous low permittivity and permeability. Cut-wire structure is selected to realize the low electromagnetic (EM) parameters and low loss on the resonance brim region. The full-model simulations show good agreement with theoretical calculations, and illustrate that near -20dB reduction is achieved and the -10 dB bandwidth can reach up to 0.6 GHz. Compared with the cloak based on transformation electromagnetics, the design possesses advantage of simpler requirement of EM parameters and is much easier to be implemented when only backward scattering field is cared.
Effect of a cylindrical thin-shell of matter on the electrostatic self-force on a charge
Energy Technology Data Exchange (ETDEWEB)
Rubin de Celis, Emilio [Universidad de Buenos Aires y IFIBA, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina)
2016-02-15
The electrostatic self-force on a point charge in cylindrical thin-shell space-times is interpreted as the sum of a bulk field and a shell field. The bulk part corresponds to a field sourced by the test charge placed in a space-time without the shell. The shell field accounts for the discontinuity of the extrinsic curvature κ{sup p}{sub q}. An equivalent electric problem is stated, in which the effect of the shell of matter on the field is reconstructed with the electric potential produced by a non-gravitating charge distribution of total image charge Q, to interpret the shell field in both the interior and exterior regions of the space-time. The self-force on a point charge q in a locally flat geometry with a cylindrical thin-shell of matter is calculated. The charge is repelled from the shell if κ{sup p}{sub q} = κ < 0 (ordinarymatter) and attracted toward the shell if κ > 0 (exotic matter). The total image charge is zero for exterior problems, while for interior problems Q/q = κr{sub e}, with re the external radius of the shell. The procedure is general and can be applied to interpret self-forces in other space-times with shells, e.g., for locally flat wormholes we found Q{sub -+}{sup wh}/q = -1/(κ{sub wh}r{sub ±}). (orig.)
Study on seismic performance evaluation of cylindrical latticed shells supported by substructures
Maeda, Haruki; Nakazawa, Shoji
2017-10-01
This present paper discusses on analysis of the collapse mechanism and seismic performance evaluation for the cylindrical latticed shell gymnasium based on elasto-plastic dynamic response analysis. The cylindrical latticed shell supported by ductile substructures is evaluated in this study. The evaluation is based on dynamic ductility index dF and dynamic seismic performance index dIs calculated by Elasto-plastic dynamic response analyses. dF and dIs are index corresponding to a size of critical deformation. And the seismic performance is evaluated in terms of the critical deformation. A half open angle θ, a yield shear force coefficient Cy, a secondary rigidity ratio κ braces on structure and capacity critical deformation of braces are set on numerical parameters, effect the parameters on dF and dIs are investigated. In addition, a comparison between dF evaluated by elasto-plastic dynamic response analysis and dFest estimated by using equivalent linearization method is investigated, and the validity and the applicable range of the proposed estimation method in this study are confirmed.
Self-force on a charge in a locally flat geometry with a cylindrical thin-shell
de Celis, Emilio Rubín
2015-01-01
The electrostatic self-interaction of a point charge is calculated for an arbitrary position in a locally flat space-time with a cylindrical thin-shell of matter centred at a straight cosmic string. The results show a radial self-force. Near the string or asymptotically far from the thin-shell the charge is repelled from the central axis, this interaction is produced by the global deficit angle of the geometry. In the neighbourhood of the shell the charge is repelled from it if the surface energy density is positive (ordinary matter) and attracted towards the shell if the surface energy density is negative (exotic matter).
Plattenburg, Joseph; Dreyer, Jason T.; Singh, Rajendra
2017-07-01
This article extends a recent publication [MSSP (2016), 176-196] by developing a Rayleigh-Ritz model of a thin cylindrical shell to predict its response subject to concurrent active and passive damping treatments. These take the form of piezoelectric patches and a distributed cardboard liner, since the effects of such combined treatments are yet to be investigated. Furthermore, prior literature typically considers only the ;bimorph; active patch configuration (with patches on the inner and outer shell surfaces), which is not feasible with an interior passive liner treatment. Therefore, a novel configuration-termed as ;unimorph;-is proposed and included in the model. Experiments are performed on a shell with active patches (under harmonic excitation from 200 to 2000 Hz) in both the bimorph and unimorph configurations to provide evidence for the analytical model predictions. The proposed model is then employed to assess competing control system designs by examining local vs. global control schemes as well as considering several alternate active patch locations, both with and without the passive damping. Non-dimensional performance metrics are devised to facilitate comparisons of vibration attenuation among different designs. Finally, insertion loss values are measured under single-frequency excitation to evaluate several vibration control designs, and to compare the effects of alternate damping treatments.
Aeroelastic stability of cylindrical shells interacting with internal annular fluid flow
Bochkarev, S. A.; Lekomtsev, S. V.
2017-06-01
This paper is devoted to the analysis of the dynamic behavior of cylindrical shells, containing an internal annular layer of ideal fluid and subject to the external supersonic gas flow. The aerodynamic pressure is calculated based on the quasi-static aerodynamic theory. The behavior of the compressible fluid is described in terms of the perturbation velocity potential. A mathematical formulation of the problem is developed based on the classical theory of shells and virtual displacement principle. A solution of the problem involves computation of complex eigenvalues of the coupled system of equations. The paper presents the results of numerical experiments, which were performed to estimate the influence of the fluid flow velocity on the value of the static pressure in the unperturbed gas flow for shells, interacting with fluid layers of different thicknesses. The numerical simulation shows that a reduction of the fluid layer thickness and increase of the fluid velocity produce a stabilizing effect by virtue of increasing the threshold of aerodynamic stability. However, an essential reduction of the layer thickness can lead, depending on the preset combinations of boundary conditions, to a considerable growth of the stability threshold or to the onset of instability.
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Xudong Chen
2016-01-01
Full Text Available Comparison study on free vibration of circular cylindrical shells between thin and moderately thick shell theories when using the exact dynamic stiffness method (DSM formulation is presented. Firstly, both the thin and moderately thick dynamic stiffness formulations are examined. Based on the strain and kinetic energy, the vibration governing equations are expressed in the Hamilton form for both thin and moderately thick circular cylindrical shells. The dynamic stiffness is assembled in a similar way as that in classic skeletal theory. With the employment of the Wittrick-Williams algorithm, natural frequencies of circular cylindrical shells can be obtained. A FORTRAN code is written and used to compute the modal characteristics. Numerical examples are presented, verifying the proposed computational framework. Since the DSM is an exact approach, the advantages of high accuracy, no-missing frequencies, and good adaptability to various geometries and boundary conditions are demonstrated. Comprehensive parametric studies on the thickness to radius ratio (h/r and the length to radius ratio (L/r are performed. Applicable ranges of h/r are found for both thin and moderately thick DSM formulations, and influences of L/r on frequencies are also investigated. The following conclusions are reached: frequencies of moderately thick shells can be considered as alternatives to those of thin shells with high accuracy where h/r is small and L/r is large, without any observation of shear locking.
Asadi, Hamed
2017-09-01
Spacecraft and satellite are susceptible to aerothermoelastic flutter instability, which may jeopardize the mission of the spacecraft and satellite. This kind of instability may result from the coupling of the thermal radiation from the sun and the elastic deformations of aeronautical components. As a first endeavor, the aerothermoelastic flutter and buckling instabilities of functionally graded carbon nanotube reinforced composite (FG-CNTRC) cylindrical shell under simultaneous actions of aerodynamic loading and elevated temperature conditions are investigated. The formulations are derived according to the first-order shear deformation theory, Donnell shell theory in conjunction with von Karman geometrical nonlinearity. Thermomechanical properties are assumed to be temperature-dependent and modified rule of mixture is used to determine the equivalent material properties of the FG-CNTRC cylindrical shell. The quasi-steady Krumhaar's modified piston theory by taking into account the effect of panel curvature, is used to determine the aerodynamic pressure. The nonlinear dynamic equations are discretized in the circumferential and longitudinal directions using the trigonometric expression and the harmonic differential quadrature method, respectively. Effects of various influential factors, including CNT volume fraction and distribution, boundary conditions, geometrical parameters, thermal environments, freestream static pressure and Mach number on the aerothermoelastic instabilities of the FG-CNTRC cylindrical shell are studied in details. It is found that temperature rise has a significant effect on the aerothermoelastic flutter characteristics of the FG-CNTRC cylindrical shell. It is revealed that cylindrical shells with intermediate CNT volume fraction have intermediate critical dynamic pressure, while do not have, necessarily, intermediate critical buckling temperature. It is concluded that the critical circumferential mode number (mCr) corresponding to the
Sun, Dongming; Wang, Sheng; Hata, Seiichi; Sakurai, Junpei; Shimokohbe, Akira
2009-03-01
A thin film rotating sputtering system is presented for fabrication of a circular cylindrical shell (CCS). The length, diameter, and thickness of the CCS are 5.0 mm, 1.5 mm, and 25 mum, respectively. To investigate the vibration characteristics, the CCS is fabricated on the outer surface of a piezoelectric ceramic tube (PCT). The vibration of PCT excited by driving voltage signals causes the vibration of the CCS, and the vibration characteristics can be measured using a laser Doppler vibrometer system. Furthermore, a finite element method (FEM) simulation and 2 analytical calculation methods are proposed for comparison with the measurement results. The frequency factor, the key factor that dominates the effective ranges of the 2 analytical methods, is determined as a value of 0.92 through a series of discussions. Combining the results of the 2 analytical calculation methods, good agreement of the analytical, FEM, and measurement results is obtained.
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Mosaffa Amirhossein
2013-01-01
Full Text Available Results are reported of an investigation of the solidification of a phase change material (PCM in a cylindrical shell thermal energy storage with radial internal fins. An approximate analytical solution is presented for two cases. In case 1, the inner wall is kept at a constant temperature and, in case 2, a constant heat flux is imposed on the inner wall. In both cases, the outer wall is insulated. The results are compared to those for a numerical approach based on an enthalpy method. The results show that the analytical model satisfactory estimates the solid-liquid interface. In addition, a comparative study is reported of the solidified fraction of encapsulated PCM for different geometric configurations of finned storage having the same volume and surface area of heat transfer.
Design Optimization and Residual Strength Assessment of a Cylindrical Composite Shell Structure
Rais-Rohani, Masoud
2000-01-01
A summary of research conducted during the specified period is presented. The research objectives included the investigation of an efficient technique for the design optimization and residual strength assessment of a semi-monocoque cylindrical shell structure made of composite materials. The response surface methodology is used in modeling the buckling response of individual skin panels under the combined axial compression and shear loading. These models are inserted into the MSC/NASTRAN code for design optimization of the cylindrical structure under a combined bending-torsion loading condition. The comparison between the monolithic and sandwich skin design cases indicated a 35% weight saving in using sandwich skin panels. In addition, the residual strength of the optimum design was obtained by identifying the most critical region of the structure and introducing a damage in the form of skin-stringer and skin-stringer-frame detachment. The comparison between the two skin design concepts indicated that the sandwich skin design is capable of retaining a higher residual strength than its monolithic counterpart. The results of this investigation are presented and discussed in this report.
The effect of a weak nonlinearity on the lowest cut-off frequencies of a cylindrical shell
Andrianov, I. V.; Kaplunov, J.; Kudaibergenov, A. K.; Manevitch, L. I.
2018-02-01
The plane strain problem for a thin circular cylindrical shell is considered within the framework of the Sanders-Koiter theory. The relative shell thickness and displacement amplitude are chosen to be of the same asymptotic order. The leading nonlinear correction to the lowest cut-off frequencies is derived using the method of multiple scales. In contrast to the traditional two-mode Galerkin expansions assuming inextensibility of the shell transverse cross section, the developed fourth-order asymptotic scheme operates with five angular modes. The obtained results reveal asymptotic inconsistency of previous approximate solutions to the problem.
The Influence on Modal Parameters of Thin Cylindrical Shell under Bolt Looseness Boundary
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Hui Li
2016-01-01
Full Text Available The influence on modal parameters of thin cylindrical shell (TCS under bolt looseness boundary is investigated. Firstly, bolt looseness boundary of the shell is divided into two types, that is, different bolt looseness numbers and different bolt looseness levels, and natural frequencies and mode shapes are calculated by finite element method to roughly master vibration characteristics of TCS under these conditions. Then, the following measurements and identification techniques are used to get precise frequency, damping, and shape results; for example, noncontact laser Doppler vibrometer and vibration shaker with excitation level being precisely controlled are used in the test system; “preexperiment” is adopted to determine the required tightening torque and verify fixed constraint boundary; the small-segment FFT processing technique is employed to accurately measure nature frequency and laser rotating scanning technique is used to get shape results with high efficiency. Finally, based on the measured results obtained by the above techniques, the influence on modal parameters of TCS under two types of bolt looseness boundaries is analyzed and discussed. It can be found that bolt looseness boundary can significantly affect frequency and damping results which might be caused by changes of nonlinear stiffness and damping and in bolt looseness positions.
Daneshjou, K.; Talebitooti, R.; Kornokar, M.
2017-04-01
This paper presents an analytical solution for sound transmission through a multilayered cylindrical shell with bonded-unbonded (BU) configuration. The multilayered cylindrical shell, which is composed of an outer layer of functionally graded material (FGM) and an inner isotropic layer with a poroelastic core and an air gap, is assumed to be infinitely long and is subjected to a plane wave on its external sidewall. To describe the poroelastic core, the extended full method (EFM) is applied based on Biot's theory. Contrary to previous methods, the EFM completely models the poroelastic cylindrical shell in three dimensions. In addition, the motions of both FGM and isotropic shells are described with the first order shear deformation theory (FSDT). Unlike the simplified method, the EFM does not need to identify the frequency ranges where one of the airborne or frame waves is dominant in BU configuration. In fact, utilizing the EFM for BU configuration permits obtaining the sound transmission loss (TL) irrespective of the dominant wave, which significantly reduces the computational work. Moreover, comparing with the previous models, the EFM provides more accurate results as it does not ignore any term in the modeling. Furthermore, the advantages of the BU-FGM shell in enhancing the TL are demonstrated with respect to the BB-isotropic configuration. It is shown that presence of the FGM in addition to the poroelastic material in a structure yields thermal insulation and improves soundproofing characteristics in a broadband frequency range.
Starnes, James H.; Rose, Cheryl A.
1998-01-01
The results of an analytical study of the nonlinear response of a thin unstiffened aluminum cylindrical shell with a longitudinal crack are presented. The shell is analyzed with a nonlinear shell analysis code that maintains the shell in a nonlinear equilibrium state while the crack is grown. The analysis accurately accounts for global and local structural response phenomena. Results are presented for internal pressure, axial compression, and combined internal pressure and axial compression loads. The effects of varying crack length on the nonlinear response of the shell subjected to internal pressure are described. The effects of varying crack length on the prebuckling, buckling and postbuckling responses of the shell subjected to axial compression, and subjected to combined internal pressure and axial compression are also described. The results indicate that the nonlinear interaction between the in-plane stress resultants and the out-of-plane displacements near a crack can significantly affect the structural response of the shell. The results also indicate that crack growth instabilities and shell buckling instabilities can both affect the response of the shell as the crack length is increased.
HL-20 structural design comparison - Conformal shell versus cylindrical crew compartment
Bush, Lance B.; Wahls, Deborah M.; Robinson, James C.
1993-01-01
Extensive studies have been performed at NASA Langley Research Center (LaRC) on personnel launch systems (PLS) concepts. The primary mission of a PLS is the transport of Space Station crew members from Earth to the Space Station and return. The NASA LaRC PLS studies have led to the design of a lifting body configuration named the HL-20. In this study, two different HL-20 structural configurations are evaluated. The two configurations are deemed the conformal shell and the cylindrical crew compartment. The configurations are based on two different concerns for maintenance and operations. One configuration allows for access to subsystems while on-orbit from the interior, while the other allows for easy access to the subsystems during ground maintenance and operations. For each concept, the total structural weight required to sustain the applied loads is quantified through a structural evaluation. Structural weight for both configurations is compared along with the particular attributes of each. Analyses of both configurations indicate no appreciable weight or load relief advantage of one concept over the other. Maintainability and operability, therefore become the primary discriminator, leading to a choice of a crew compartment configuration.
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Mohammad Zamani Nejad
2014-01-01
Full Text Available Using disk form multilayers, a semi-analytical solution has been derived for determination of displacements and stresses in a rotating cylindrical shell with variable thickness under uniform pressure. The thick cylinder is divided into disk form layers form with their thickness corresponding to the thickness of the cylinder. Due to the existence of shear stress in the thick cylindrical shell with variable thickness, the equations governing disk layers are obtained based on first-order shear deformation theory (FSDT. These equations are in the form of a set of general differential equations. Given that the cylinder is divided into n disks, n sets of differential equations are obtained. The solution of this set of equations, applying the boundary conditions and continuity conditions between the layers, yields displacements and stresses. A numerical solution using finite element method (FEM is also presented and good agreement was found.
Hagihara, Seiya; Miyazaki, Noriyuki
1998-05-01
Cylindrical shells are utilized as structural elements of nuclear power plants, heat exchangers or pressure vessels, which are operated under elevated temperature. Creep buckling is one of the failure modes of structures at elevated temperature. In some experiments conducted by other authors, axially compressive cylindrical shells with a large ratio of radius to thickness were observed to buckle with circumferential waves. It is observed that the circumferential waves occur due to bifurcation buckling. But, the critical time and the minimum loading for bifurcation buckling obtained from calculations of finite element analyses are not in very good agreement with those of the experiments. One of the reasons for the disagreement is considered to be that the creep constitutive equations employed in many previous analyses represent the steady creep. The creep phenomena usually have primary creep period, steady creep one and tertiary creep one. A creep strain - time relation through the three periods can be simulated by using a constitutive equation based on creep damage mechanics. In the present analysis, we analyzed the bifurcation creep buckling of circular cylindrical shells subjected to axial compression by the use of the finite element method taking account of the creep damage mechanics proposeol by of Kachanov-Rabotonov.
Meyer, V.; Maxit, L.; Renou, Y.; Audoly, C.
2017-09-01
The understanding of the influence of non-axisymmetric internal frames on the vibroacoustic behavior of a stiffened cylindrical shell is of high interest for the naval or aeronautic industries. Several numerical studies have shown that the non-axisymmetric internal frame can increase the radiation efficiency significantly in the case of a mechanical point force. However, less attention has been paid to the experimental verification of this statement. That is why this paper proposes to compare the radiation efficiency estimated experimentally for a stiffened cylindrical shell with and without internal frames. The experimental process is based on scanning laser vibrometer measurements of the vibrations on the surface of the shell. A transform of the vibratory field in the wavenumber domain is then performed. It allows estimating the far-field radiated pressure with the stationary phase theorem. An increase of the radiation efficiency is observed in the low frequencies. Analysis of the velocity field in the physical and wavenumber spaces allows highlighting the coupling of the circumferential orders at the origin of the increase in the radiation efficiency.
Kang, Jae-Hoon
2012-08-01
A three-dimensional (3-D) method of analysis is presented for determining the free vibration frequencies of joined thick conical-cylindrical shells of revolution with variable thickness. Unlike conventional shell theories, which are mathematically two-dimensional (2-D), the present method is based upon the 3-D dynamic equations of elasticity. Displacement components ur, uθ, and uz in the radial, circumferential, and axial directions, respectively, are taken to be periodic in θ and in time, and algebraic polynomials in the r and z directions. Potential (strain) and kinetic energies of the joined shells are formulated, and the Ritz method is used to solve the eigenvalue problem, thus yielding upper bound values of the frequencies by minimizing the frequencies. As the degree of the polynomials is increased, frequencies converge to the exact values. Convergence to four-digit exactitude is demonstrated for the first five frequencies. Natural frequencies are presented for different boundary conditions. Comparisons are made between the frequencies from the present 3-D Ritz method and 2-D thin shell theories by previous researchers.
Energy Technology Data Exchange (ETDEWEB)
Setare, M.R. [Department of Science, Campus of Bijar, University of Kurdistan,Bijar (Iran, Islamic Republic of); Sepehri, A. [Faculty of Physics, Shahid Bahonar University,P.O. Box 76175, Kerman (Iran, Islamic Republic of)
2015-03-16
In this paper, we consider the stability of cylindrical wormholes during evolution of universe from inflation to late time acceleration epochs. We show that there are two types of cylindrical wormholes. The first type is produced at the corresponding point where k black F-strings are transited to BIon configuration. This wormhole transfers energy from extra dimensions into our universe, causes inflation, loses it’s energy and vanishes. The second type of cylindrical wormhole is created by a tachyonic potential and causes a new phase of acceleration. We show that wormhole parameters grow faster than the scale factor in this era, overtake it at ripping time and lead to the destruction of universe at big rip singularity.
Bifurcation and Localization Instabilities in Cylindrical Shells under Bending. Part 1. Experiments
1991-01-01
bending specimens. The stress-strain curves obtained were fitted with the Ramberg - Osgood fit given by The fit parameters calculated from each test...Dm, Dmi,, maximum and minimum shell diameter Do shell mean diameter E Young’s modulus L shell half length M moment Mo aoD0t n Ramberg - Osgood ...axial ripple half-wave length AD half-wave length of predicted ripples (J 2 def. Theory) ay Ramberg - Osgood yield parameter ao yield stress -E0 thickness
Directory of Open Access Journals (Sweden)
Rossikhin Yury A.
2018-01-01
Full Text Available Non-linear damped vibrations of a cylindrical shell embedded into a fractional derivative medium are investigated for the case of the combinational internal resonance, resulting in modal interaction, using two different numerical methods with further comparison of the results obtained. The damping properties of the surrounding medium are described by the fractional derivative Kelvin-Voigt model utilizing the Riemann-Liouville fractional derivatives. Within the first method, the generalized displacements of a coupled set of nonlinear ordinary differential equations of the second order are estimated using numerical solution of nonlinear multi-term fractional differential equations by the procedure based on the reduction of the problem to a system of fractional differential equations. According to the second method, the amplitudes and phases of nonlinear vibrations are estimated from the governing nonlinear differential equations describing amplitude-and-phase modulations for the case of the combinational internal resonance. A good agreement in results is declared.
Rahman, T.; Jansen, E.L.; Tiso, P.
2011-01-01
In this paper, a finite element-based approach for nonlinear vibration analysis of shell structures is presented. The approach makes use of a perturbation method that gives an approximation for the amplitude-frequency relation of the structure. The method is formulated using a functional notation
Li, Yi-Wei; Elishakoff, Isaac; Starnes, James H., Jr.; Bushnell, David
1998-01-01
This study is an extension of a previous investigation of the combined effect of axisymmetric thickness variation and axisymmetric initial geometric imperfection on buckling of isotropic shells under uniform axial compression. Here the anisotropic cylindrical shells are investigated by means of Koiter's energy criterion. An asymptotic formula is derived which can be used to determine the critical buckling load for composite shells with combined initial geometric imperfection and thickness variation. Results are compared with those obtained by the software packages BOSOR4 and PANDA2.
A Review of the Theory and Methods for Determining Dynamic Pulse Buckling of Cylindrical Shells
1989-09-01
allowed t lie shells to buckle, deform plastica iv and damip owi to a fiital deformed shape. The permanent peak deformations for a range of imnpulse...8217nonlinear dynamic buckling analysis is frequently beyond the current state of the art ’. Lindberg and Kennedy [26], investigate plastic flow buckling theory...The shadd regions of Figure B.1 art 71 regions of instability. The effect of damping on the system is to shift the regions of instability away from the
Fractal dimension method for exciton in cylindrical GaAs/AlxGa1‑xAs core-shell-cap nanowires
Sun, Hui; Wu, Zhenhua; Tian, Qiang
2017-11-01
By use of the fractal dimension method, the binding energies of heavy-hole exciton and light-hole exciton in cylindrical GaAs/AlxGa1‑xAs core-shell-cap nanowire are explored. In this study, the exciton is confined in GaAs shell of the GaAs/AlxGa1‑xAs core-shell-cap nanowire for a given aluminum concentration of x=0.3. The numerical results of heavy-hole exciton binding energy, light-hole exciton binding energy and fractal dimension parameter are worked out as functions of shell width and core radius. It has been shown by the calculated results that heavy-hole exciton binding energy and light-hole exciton binding energy firstly increase and then decrease as the shell width increases. When the core radius increases, both the heavy-hole exciton binding energy and light-hole exciton binding energy increase gradually. Exciton problems in GaAs shell of the cylindrical GaAs/AlxGa1‑xAs core-shell-cap nanowire are solved in a simple manner to avoid complex and lengthy calculations by using the fractal dimension method.
1983-10-01
cofactors 011, D129 .... D33. Let u - Dilo , v D1 2Oi , w D1301 (sum on i, 1= 1,2,3) (10) and substitute these expressions in the three equations in...orthotropic shells. In some publications, even certain terms in equation (14) are neglected. In the following analysis , some of these negligibly small...34 Journal of Composite Materials 1, 1967, pp. 414-423. 5. Calcote, L. R., The Analysis of Laminated Composite Structures, Van Nostrand Reinhold Co., New
Lee, Joon-Ho; Jeong, Woo Jin; Seo, Junbeom; Shin, Mincheol
2018-01-01
Gate-all-around silicon nanowire transistors (SNWTs) are recognized as promising candidates to reduce problems due to quantum effects in conventional nano-transistors. In this study we investigate whether structural modification of SNWTs leads to improved performance. A model calculation for a transistor with a channel length of several nanometers requires a quantum transport simulator, and we use a Wigner transport equation (WTE) discretized by a third-order upwind differential scheme (TDS) suggested by Yamada et al. (2009) for quantum transport simulations of gate-all-around silicon-shell nanowire transistors (SSNWTs), core gate SSNWTs (CG-SSNWTs), and independent CG-SSNWTs (ICG-SSNWTs). A WTE discretized by the TDS is known to produce highly accurate results. The SSNWT has a structure in which an insulator cylinder is inserted into the center axis of the SNWT, and the CG-SSNWT has a structure in which a core gate is inserted into the center axis of the SSNWT. The calculations show that the performances of the SSNWTs are improved by introducing the Si-shell structure and the core gate. The ICG-SSNWTs are identical in structure to the CG-SSNWTs, but the outer and core gates are independently biased. The calculations for the ICG-SSNWTs show that the threshold voltage can be controlled using the difference between the core and outer gate voltages.
Directory of Open Access Journals (Sweden)
Pham Minh Vuong
Full Text Available Abstract The main aim of this paper is to investigate analytically nonlinear buckling and post-buckling of functionally graded stiffened circular cylindrical shells filled inside by Pasternak two-parameter elastic foundations in thermal environments and under axial compression load and external pressure by analytical approach. Shells are reinforced by closely spaced rings and stringers. The material properties of shell and the stiffeners are assumed to be continuously graded in the thickness direction. Using the Reddy third order shear deformation shell theory, stress function method and Lekhnitskii smeared stiffeners technique, the governing equations are derived. The closed form to determine critical axial load and post-buckling load-deflection curves are obtained by Galerkin method. The effects of temperature, stiffener, foundation, material and dimensional parameters on the stability behavior of shells are shown. The accuracy of the presented method is affirmed by comparisons with well-known results in references. The results shown for thick cylindrical shells, the use of TSDT for determining their critical buckling load is necessary and more suitable.
Numerical analysis of the cylindrical rigidity of the vertical steel tank shell
Chirkov, Sergey; Tarasenko, Alexander; Chepur, Petr
2017-10-01
The paper deals with the study of rigidity of a vertical steel cylindrical tank and its structural elements with the development of inhomogeneous subsidence in ANSYS software complex. The limiting case is considered in this paper: a complete absence of a base sector that varies along an arc of a circle. The subsidence zone is modeled by the parameter n. A finite-element model of vertical 20000 m3 steel tank has been created, taking into account all structural elements of tank metal structures, including the support ring, beam frame and roof sheets. Various combinations of vertical steel tank loading are analyzed. For operational loads, the most unfavorable combination is considered. Calculations were performed for the filled and emptied tank. Values of the maximum possible deformations of the outer contour of the bottom are obtained with the development of inhomogeneous base subsidence for the given tank size. The obtained parameters of intrinsic rigidity (deformability) of vertical steel tank can be used in the development of new regulatory and technical documentation for tanks.
Directory of Open Access Journals (Sweden)
Masoud Biglarkhani
2017-01-01
Full Text Available Incremental explosive analysis (IEA is addressed as an applicable method for performance-based assessment of stiffened and unstiffened cylindrical shells subjected to underwater explosion (UNDEX loading. In fact, this method is inspired by the incremental dynamic analysis (IDA which is a known parametric analysis method in the field of earthquake engineering. This paper aims to introduce the application of IEA approach in UNDEX in order to estimate different limit states and deterministic assessment of cylindrical shells, considering the uncertainty of loading conditions. The local, bay, and general buckling modes are defined as limit states for performance calculation. Different standoff distances and depth parameters combining several loading conditions are considered. The explosive loading intensity is specified and scaled in several levels to force the structure through the entire range of its behavior. The results are plotted in terms of a damage measure (DM versus selected intensity measure (IM. The statistical treatment of the obtained multi-IEA curves is performed to summarize the results in a predictive mode. Finally, the fragility curves as damage probability indicators of shells in UNDEX loading are extracted. Results show that the IEA is a promising method for performance-based assessment of cylindrical shells subjected to UNDEX loading.
Thermal Effect on Bistable Behaviour of T700/3234 Anti-symmetric Cylindrical Shells
Directory of Open Access Journals (Sweden)
ZHANG Zheng
2016-10-01
Full Text Available The temperature effects on the bi-stable characteristics of T700/3234 anti-symmetric carbon-fiber composite structure were studied. Three different layup specimens were prepared through composite molding process.The two points loading method was used in the experiment. The modified experimental testing machine (the experimental testing machine could be used to induce the bistable composite shell to snap between the two stable shapes, and continually capture the data in the experimental process. was related to tensile testing machine at present. The load-displacement curvatures under the temperature of 20℃,40℃,60℃ and 80℃ were given. The snap load was recorded and the photos were taken in the experimental process. After the experiment, the detailed data of curvature and twisting curvature were obtained by image processing technology. The variation law of the coiled-up radius, out-of-plane displacement, maximum snap-through and snap-back loads were analyzed. The effect on the composite structure was also discussed.The result shows that the thermal effect is vital to the bistable snaps process, and corresponding influence trends to the snap through and snap back process are given.
Heard, W. L., Jr.; Anderson, M. S.; Slysh, P.
1976-01-01
An engineering procedure is presented for calculating the compressive buckling strength of isogrid cylinders using shell of revolution techniques and accounting for loading beyond the material proportional limit and/or local buckling of the skin prior to general buckling. A general nondimensional chart is presented which can be used in conjunction with formulas based on simple deformation plasticity theory to calculate postbuckling stiffnesses of the skin. The stiffening grid system is treated as an equivalent isotropic grid layer. Stiffnesses are determined for this grid layer, when loaded beyond the proportional limit, by the same plasticity theory used for the skin and a nonlinear stress-strain curve constructed from simple isogrid-handbook formulas and standard-reference-manual stress-strain curves for the material involved. Comparison of prebuckling strains and buckling results obtained by this procedure with data from a large isogrid-cylinder test is excellent with the calculated buckling load no more than 4 percent greater than the test value.
Meyer, V.; Maxit, L.; Guyader, J.-L.; Leissing, T.
2016-01-01
The vibroacoustic behavior of axisymmetric stiffened shells immersed in water has been intensively studied in the past. On the contrary, little attention has been paid to the modeling of these shells coupled to non-axisymmetric internal frames. Indeed, breaking the axisymmetry couples the circumferential orders of the Fourier series and considerably increases the computational costs. In order to tackle this issue, we propose a sub-structuring approach called the Condensed Transfer Function (CTF) method that will allow assembling a model of axisymmetric stiffened shell with models of non-axisymmetric internal frames. The CTF method is developed in the general case of mechanical subsystems coupled along curves. A set of orthonormal functions called condensation functions, which depend on the curvilinear abscissa along the coupling line, is considered. This set is then used as a basis for approximating and decomposing the displacements and the applied forces at the line junctions. Thanks to the definition and calculation of condensed transfer functions for each uncoupled subsystem and by using the superposition principle for passive linear systems, the behavior of the coupled subsystems can be deduced. A plane plate is considered as a test case to study the convergence of the method with respect to the type and the number of condensation functions taken into account. The CTF method is then applied to couple a submerged non-periodically stiffened shell described using the Circumferential Admittance Approach (CAA) with internal substructures described by Finite Element Method (FEM). The influence of non-axisymmetric internal substructures can finally be studied and it is shown that it tends to increase the radiation efficiency of the shell and can modify the vibrational and acoustic energy distribution.
Schmidt, J. M.; Cairns, Iver H.; Xie, Hong; St. Cyr, O. C.; Gopalswamy, N.
2016-01-01
Coronal mass ejections (CMEs) are major transient phenomena in the solar corona that are observed with ground-based and spacecraft-based coronagraphs in white light or with in situ measurements by spacecraft. CMEs transport mass and momentum and often drive shocks. In order to derive the CME and shock trajectories with high precision, we apply the graduated cylindrical shell (GCS) model to fit a flux rope to the CME directed toward STEREO A after about 19:00 UT on 29 November 2013 and check the quality of the heliocentric distance-time evaluations by carrying out a three-dimensional magnetohydrodynamic (MHD) simulation of the same CME with the Block Adaptive Tree Solar-Wind Roe Upwind Scheme (BATS-R-US) code. Heliocentric distances of the CME and shock leading edges are determined from the simulated white light images and magnetic field strength data. We find very good agreement between the predicted and observed heliocentric distances, showing that the GCS model and the BATS-R-US simulation approach work very well and are consistent. In order to assess the validity of CME and shock identification criteria in coronagraph images, we also compute synthetic white light images of the CME and shock. We find that the outer edge of a cloud-like illuminated area in the observed and predicted images in fact coincides with the leading edge of the CME flux rope and that the outer edge of a faint illuminated band in front of the CME leading edge coincides with the CME-driven shock front.
Directory of Open Access Journals (Sweden)
Lijie Li
2017-01-01
Full Text Available The aim of this paper is to extend the modified Fourier-Ritz approach to evaluate the free vibration of four-parameter functionally graded moderately thick cylindrical, conical, spherical panels and shells of revolution with general boundary conditions. The first-order shear deformation theory is employed to formulate the theoretical model. In the modified Fourier-Ritz approach, the admissible functions of the structure elements are expanded into the improved Fourier series which consist of two-dimensional (2D Fourier cosine series and auxiliary functions to eliminate all the relevant discontinuities of the displacements and their derivatives at the edges regardless of boundary conditions and then solve the natural frequencies by means of the Ritz method. As one merit of this paper, the functionally graded cylindrical, conical, spherical shells are, respectively, regarded as a special functionally graded cylindrical, conical, spherical panels, and the coupling spring technology is introduced to ensure the kinematic and physical compatibility at the common meridian. The excellent accuracy and reliability of the unified computational model are compared with the results found in the literatures.
Directory of Open Access Journals (Sweden)
B D. Kashfutdinov
2017-01-01
Full Text Available The paper deals with a modal analysis of the elastic cylindrical shell with a clamped bottom partially filled with fluid in open source Code_Aster software using the finite element method. Natural frequencies and modes obtained in Code_Aster are compared to experimental and theoretical data. The aim of this paper is to prove that Code_Aster has all necessary tools for solving fluid structure interaction problems. Also, Code_Aster can be used in the industrial projects as an alternative to commercial software. The available free pre- and post-processors with a graphical user interface that is compatible with Code_Aster allow creating complex models and processing the results.The paper presents new validation results of open source Code_Aster software used to calculate small natural modes of the cylindrical shell partially filled with non-viscous compressible barotropic fluid under gravity field.The displacement of the middle surface of thin shell and the displacement of the fluid relative to the equilibrium position are described by coupled hydro-elasticity problem. The fluid flow is considered to be potential. The finite element method (FEM is used. The features of computational model are described. The resolution equation has symmetrical block matrices. To compare the results, is discussed the well-known modal analysis problem of cylindrical shell with flat non-deformable bottom, filled with a compressible fluid. The numerical parameters of the scheme were chosen in accordance with well-known experimental and analytical data. Three cases were taken into account: an empty, a partially filled and a full-filled cylindrical shell.The frequencies of Code_Aster are in good agreement with those, obtained in experiment, analytical solution, as well as with results obtained by FEM in other software. The difference between experiment and analytical solution in software is approximately the same. The obtained results extend a set of validation tests for
DEFF Research Database (Denmark)
Rahmani, Omid; Khalili, S.M.R.; Thomsen, Ole Thybo
2012-01-01
A new model based on the high order sandwich panel theory is proposed to study the effect of external loads on the free vibration of circular cylindrical composite sandwich shells with transversely compliant core, including also the calculation of the buckling loads. In the present model, in cont......A new model based on the high order sandwich panel theory is proposed to study the effect of external loads on the free vibration of circular cylindrical composite sandwich shells with transversely compliant core, including also the calculation of the buckling loads. In the present model......, in contrast to most of the available sandwich plate and shell theories, no prior assumptions are made with respect to the displacement field in the core. Herein the displacement and the stress fields of the core material are determined through a 3D elasticity solution. The performance of the present theory...... is compared with that of other sandwich theories by the presentation of comparative results obtained for several examples encompassing different material properties and geometric parameters. It is shown that the present model produce results of very high accuracy, and it is suggested that the present model...
Existence of equilibrium states of hollow elastic cylinders submerged in a fluid
Directory of Open Access Journals (Sweden)
M. B. M. Elgindi
1992-01-01
Full Text Available This paper is concerned with the existence of equilibrium states of thin-walled elastic, cylindrical shell fully or partially submerged in a fluid. This problem obviously serves as a model for many problems with engineering importance. Previous studies on the deformation of the shell have assumed that the pressure due to the fluid is uniform. This paper takes into consideration the non-uniformity of the pressure by taking into account the effect of gravity. The presence of a pressure gradient brings additional parameters to the problem which in turn lead to the consideration of several boundary value problems.
Liu, Yu; He, Chuanbo
2015-12-01
In this discussion, the corrections to the errors found in the derivations and the numerical code of a recent analytical study (Zhou et al. Journal of Sound and Vibration 333 (7) (2014) 1972-1990) on sound transmission through double-walled cylindrical shells lined with poroelastic material are presented and discussed, as well as the further effect of the external mean flow on the transmission loss. After applying the corrections, the locations of the characteristic frequencies of thin shells remain unchanged, as well as the TL results above the ring frequency where BU and UU remain the best configurations in sound insulation performance. In the low-frequency region below the ring frequency, however, the corrections attenuate the TL amplitude significantly for BU and UU, and hence the BB configuration exhibits the best performance which is consistent with previous observations for flat sandwich panels.
Martinez, Loïc; Morvan, Bruno; Izbicki, Jean Louis
2004-04-01
A new 4D space-time-wave number-frequency representation Z(x,t,k,f) is introduced. The Z(x,t,k,f) representation is used for processing 2D space-time signal collection issued from wave propagation along a 1D medium. This representation is an extension along the time dimension of the space-wave number-frequency representation. The Z(x,t,k,f) representation is obtained by short time-space 2D Fourier transforming the space-time collection. The Z(x,t,k,f) representation allows the characterization transient aspects of wave generation and propagation in both space and time dimensions. The Z(x,t,k,f) representation is used to experimentally investigate Lamb wave generation and propagation around a cylindrical shell (relative thickness is equal to 0.03) surrounded by water and excited by a pulse (0.1 micros duration with 1-5 MHz transducers). Three kinds of fluids have been used inside the shell: air, water, propanol. In all the cases, the Z(x,t,k,f) analysis clearly identify the reflected field on the insonified side of the shell and it allows the measurement of the local reflection coefficients R(x,t,k,f). The generation and the propagation of Lamb waves are also quantified. For the liquid filled shells, the multiple internal reflections are revealed by Z(x,t,k,f) analysis: the local transmission coefficients T(x,t,k,f) are also measured. When local matching conditions allows Lamb wave generation, the multiple regeneration of Lamb wave is observed. Based on these results, a link is establish toward the theoretical results obtained by steady state approach and Sommerfeld-Watson transform.
Hussain, Muzamal; Naeem, M. Nawaz; Shahzad, Aamir; He, Maogang
2017-04-01
The vibration analysis, based on the Donnell thin shell theory, of single-walled carbon nanotubes (SWCNTs) has been investigated. The wave propagation approach in standard eigenvalue form has been employed in order to derive the characteristic frequency equation describing the natural frequencies of vibration in SWCNTs. The complex exponential functions, with the axial modal numbers that depend on the boundary conditions stated at edges of a carbon nanotube, have been used to compute the axial modal dependence. In our new investigations, the vibration frequency spectra are obtained and calculated for various physical parameters like length-to-diameter ratios for armchair and zigzag SWCNTs for different modes and in-plane rigidity and mass density per unit lateral area for armchair and zigzag SWCNTs on the vibration frequencies. The computer software MATLAB is used in order to compute these frequencies of the SWCNTs. The results obtained from wave propagation method are found to be in satisfactory agreement with that obtained through the previously known numerical molecular dynamics simulations.
Harper, Catherine
2006-01-01
Susie MacMurray's Shell installation manifests in Pallant House Gallery, Chichester, like some pulsing exotica, a heavily-textured wall-paper, darkly decorative, heavily luxurious, broodingly present, with more than a hint of the uncanny or the gothic. A remarkable undertaking by an artist of significance, this work's life-span will be just one year, and then it will disappear, leaving no physical trace, but undoubtedly contributing in a much less tangible way to an already rich layering of n...
Indian Academy of Sciences (India)
equations for the scattering of electromagnetic radiation by particles with spherical or cylindrical symmetry. Aden and Kerker have published complete details of scattering from concentric spherical shells in 1951 [28]. In Mie theory, the harmonically oscillating electromagnetic fields are expressed in terms of a set of spherical ...
National Oceanic and Atmospheric Administration, Department of Commerce — The Submerged Lands Act (43 U.S.C. Section 1301 et seq.) grants coastal states title to natural resources located within their coastal submerged lands and navigable...
DEFF Research Database (Denmark)
Zhang, Jingjing; Mortensen, N. Asger
2011-01-01
We propose a cylindrical invisibility cloak achieved utilizing two dimensional split-ring resonator structured metamaterials at microwave frequencies. The cloak has spatially uniform parameters in the axial direction, and can work very well even when the cloak shell is very thin compared...... with the concealed object and the working wavelength. Numerical simulation is performed to verify the functionality of the cloak, where the cloak layer is only around 1/4 of the operating wavelength. Our work provides a feasible solution to the experimental realization of cloaks with ideal parameters....
Cylindrical metamaterial-based subwavelength antenna
DEFF Research Database (Denmark)
Erentok, Aycan; Kim, Oleksiy S.; Arslanagic, Samel
2009-01-01
A subwavelength monopole antenna radiating in the presence of a truncated cylindrical shell, which has a capped top face and is made of a negative permittivity metamaterial, is analyzed numerically by a method of moments for the volume-surface integral equation oil the one hand, and a finite...
2010-01-01
Crashes in which cars are submerged in deep water or in a ditch are often complicated and serious. Considering their severity and the fact that approximately half the fatalities in this crash type are not due to drowning but to injury, preventive measures are to be preferred above measures that have
Rotation, inversion and perversion in anisotropic elastic cylindrical tubes and membranes
Goriely, A.
2013-03-06
Cylindrical tubes and membranes are universal structural elements found in biology and engineering over a wide range of scales.Working in the framework of nonlinear elasticity, we consider the possible deformations of elastic cylindrical shells reinforced by one or two families of fibres. We consider both small and large deformations and the reduction from thick cylindrical shells (tubes) to thin shells (cylindrical membranes). In particular, a number of universal parameter regimes can be identified where the response behaviour of the cylinder is qualitatively different. This include the possibility of inversion of twist or axial strain when the cylinder is subject to internal pressure. Copyright © The Royal Society 2013.
Acoustically Driven Vibrations in Cylindrical Structures
Energy Technology Data Exchange (ETDEWEB)
Chambers, David H. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2013-10-11
The purpose of this investigation is to explore the interaction of acoustics and vibration in fluid-filled cylindrical structures. Our emphasis is on describing longitudinal (axial) propagation within the structure for acoustic signals that enter externally. This paper reviews the historical and theoretical treatments of the relevant phenomenon important to the propagation of these signals along pipe structures. Our specific contribution is a detailed analysis of how external acoustic signals are coupled to a free standing pipe. There have been numerous phenomena for which these analyses are applicable. They have ranged from physical property measurements, to indoor environmental noise abatement, and onto quite significant explorations of active and passive submerged structures.
Wave forces limit the establishment of submerged macrophytes in large shallow lakes
Zuidam, van B.G.; Peeters, E.T.H.M.
2015-01-01
We studied the effect of waves on submerged macrophytes and hypothesized that exposure to large wave forces can hamper seedling establishment. In an indoor experiment in cylindrical mesocosms we tested whether large wave forces indeed inhibited the establishment of Chara globularis and Potamogeton
Optimization of submerged vane parameters
Indian Academy of Sciences (India)
Submerged vanes are airfoils which are in general placed at certain angle with respect to the flow direction in a channel to induce artificial circulations downstream. By virtue of these artificially generated circulations, submerged vanes were utilized to protect banks of rivers against erosion, to control shifting of rivers, to avoid ...
Optimization of submerged vane parameters
Indian Academy of Sciences (India)
H Sharma
velocities simulated from CFD using standard k-x model were very much in accordance with what it was measured by Wang and Odgaard [4]. Thus, model can be used to study the turbulence characteristics around submerged vanes and to predict various parameters downstream of the submerged vanes. After the model ...
Amabili, M.
2014-03-01
Bich and Xuan Nguyen [1] studied nonlinear free and forced vibrations of FG shells under pre-load compression at constant temperature. Based on Donnell's shell theory and neglecting in-plane inertia, they employed a single-mode Galerkin approximation to discretize the transverse displacement. An averaging method was used to obtain the backbone curves while a Runge-Kutta scheme was utilized to obtain the frequency-response curves.
Submerged AUV Charging Station
Jones, Jack A.; Chao, Yi; Curtin, Thomas
2014-01-01
Autonomous Underwater Vehicles (AUVs) are becoming increasingly important for military surveillance and mine detection. Most AUVs are battery powered and have limited lifetimes of a few days to a few weeks. This greatly limits the distance that AUVs can travel underwater. Using a series of submerged AUV charging stations, AUVs could travel a limited distance to the next charging station, recharge its batteries, and continue to the next charging station, thus traveling great distances in a relatively short time, similar to the Old West “Pony Express.” One solution is to use temperature differences at various depths in the ocean to produce electricity, which is then stored in a submerged battery. It is preferred to have the upper buoy submerged a reasonable distance below the surface, so as not to be seen from above and not to be inadvertently destroyed by storms or ocean going vessels. In a previous invention, a phase change material (PCM) is melted (expanded) at warm temperatures, for example, 15 °C, and frozen (contracted) at cooler temperatures, for example, 8 °C. Tubes containing the PCM, which could be paraffin such as pentadecane, would be inserted into a container filled with hydraulic oil. When the PCM is melted (expanded), it pushes the oil out into a container that is pressurized to about 3,000 psi (approx equals 20.7 MPa). When a valve is opened, the high-pressure oil passes through a hydraulic motor, which turns a generator and charges a battery. The low-pressure oil is finally reabsorbed into the PCM canister when the PCM tubes are frozen (contracted). Some of the electricity produced could be used to control an external bladder or a motor to the tether line, such that depth cycling is continued for a very long period of time. Alternatively, after the electricity is generated by the hydraulic motor, the exiting low-pressure oil from the hydraulic motor could be vented directly to an external bladder on the AUV, such that filling of the bladder
Design aids for stiffened composite shells with cutouts
Sahoo, Sarmila
2017-01-01
This book focuses on the free vibrations of graphite-epoxy laminated composite stiffened shells with cutout both in terms of the natural frequencies and mode shapes. The dynamic analysis of shell structures, which may have complex geometry and arbitrary loading and boundary conditions, is solved efficiently by the finite element method, even including cutouts in shells. The results may be readily used by practicing engineers dealing with stiffened composite shells with cutouts. Several shell forms viz. cylindrical shell, hypar shell, conoidal shell, spherical shell, saddle shell, hyperbolic paraboloidal shell and elliptic paraboloidal shell are considered in the book. The dynamic characteristics of stiffened composite shells with cutout are described in terms of the natural frequency and mode shapes. The size of the cutouts and their positions with respect to the shell centre are varied for different edge constraints of cross-ply and angle-ply laminated composite shells. The effects of these parametric variat...
Buckling localization in a cylindrical panel under axial compression
DEFF Research Database (Denmark)
Tvergaard, Viggo; Needleman, A.
2000-01-01
Localization of an initially periodic buckling pattern is investigated for an axially compressed elastic-plastic cylindrical panel of the type occurring between axial stiffeners on cylindrical shells. The phenomenon of buckling localization and its analogy with plastic flow localization in tensile...... test specimens is discussed in general. For the cylindrical panel, it is shown that buckling localization develops shortly after a maximum load has been attained, and this occurs for a purely elastic panel as well as for elastic-plastic panels. In a case where localization occurs after a load maximum...
Stability Landscape of Shell Buckling
Virot, Emmanuel; Kreilos, Tobias; Schneider, Tobias M.; Rubinstein, Shmuel M.
2017-12-01
We measure the response of cylindrical shells to poking and identify a stability landscape, which fully characterizes the stability of perfect shells and imperfect ones in the case where a single defect dominates. We show that the landscape of stability is independent of the loading protocol and the poker geometry. Our results suggest that the complex stability of shells reduces to a low dimensional description. Tracking ridges and valleys of this landscape defines a natural phase-space coordinates for describing the stability of shells.
Cohen, Gerald A.; Haftka, Raphael T.
1989-01-01
Buckling load sensitivity calculations in the shell-of-revolution program FASOR are discussed. This development is based on Koiter's initial postbuckling theory, which has been generalized to include the effect of stiffness changes, as well as geometric imperfections. The implementation in FASOR is valid for anisotropic, as well as orthotropic, shells. Examples are presented for cylindrical panels under axial compression, complete cylindrical shells in torsion, and antisymmetric angle-ply cylindrical panels under edge shear.
On the dynamic buckling of stochastically imperfect finite cylindrical ...
African Journals Online (AJOL)
The dynamic buckling load of stochastically imperfect finite right circular cylindrical shells subjected to step loading is determined by means of regular perturbation procedures .The imperfection is assumed to be a Gaussian random function of position and consequently is homogeneous. The result obtained is implicit in the ...
Mathematical model for characterizing noise transmission into finite cylindrical structures
Li, Deyu; Vipperman, Jeffrey S.
2005-02-01
This work presents a theoretical study of the sound transmission into a finite cylinder under coupled structural and acoustic vibration. Particular attention of this study is focused on evaluating a dimensionless quantity, ``noise reduction,'' for characterizing noise transmission into a small cylindrical enclosure. An analytical expression of the exterior sound pressure resulting from an oblique plane wave impinging upon the cylindrical shell is first presented, which is approximated from the exterior sound pressure for an infinite cylindrical structure. Next, the analytical solution of the interior sound pressure is computed using modal-interaction theory for the coupled structural acoustic system. These results are then used to derive the analytical formula for the noise reduction. Finally, the model is used to predict and characterize the sound transmission into a ChamberCore cylindrical structure, and the results are compared with experimental data. The effects of incidence angle and internal acoustic damping on the sound transmission into the cylinder are also parametrically studied. .
Behavior of R/C Cylindrical Panel Subjected to Combined Axial and Shear Loadings
Hara, Takashi
2009-01-01
p. 1722-1730 Reinforced concrete (R/C) cylindrical panels have been applied to the roof or the underground structures. Also, in constructing a high rise building, an R/C wall is often used to improve the lateral rigidity of the building comparing with beam column systems under wind or seismic loading. In this paper, the behavior of R/C cylindrical shell under combined axial and lateral shear loadings is analyzed numerically. R/C cylindrical shells are often adopted for the core wa...
Drought and submergence tolerance in plants
Du, Hewei; Zhou, Yufan; Oksenberg, Nir; Ronald, Pamela
2017-11-14
The invention provides methods of genetically modified plants to increase tolerance to drought and/or submergence. The invention additionally provides plants having increased drought and/or submergence tolerance engineered using such methods.
Submerged membrane distillation for desalination of water
Francis, Lijo
2016-10-27
Submerged membrane modules for use for desalination of water are disclosed. In one or more aspects, the membrane modules can be submerged either in a feed solution tank or the feed solution can pass through the lumen side of the membrane submerged within the tank. The feed solution can be a water-based feed stream containing an amount of salt.
Dynamic analysis of conical shells conveying fluid
Senthil Kumar, D.; Ganesan, N.
2008-02-01
A formulation, based on the semi-analytical finite element method, is proposed for elastic conical shells conveying fluids. The structural equations are based on the shell element proposed by Ramasamy and Ganesan [Finite element analysis of fluid-filled isotropic cylindrical shells with constrained viscoelastic damping, Computers & Structures 70 (1998) 363-376] while the fluid model is based on velocity potential formulation used by Jayaraj et al. [A semi-analytical coupled finite element formulation for composite shells conveying fluids, Journal of Sound and Vibration 258(2) (2002) 287-307]. Dynamic pressure acting on the walls is derived from Bernoulli's equation. By imposing the requirement that the normal component of velocity of the solid and fluid are equal leads to fluid-structure coupling. The computer code developed has been validated using results available in the literature for cylindrical shells conveying fluid. The study has been carried out for conical shells of different cone angles and for boundary condition like clamped-clamped, simply supported and clamped free. In general, instability occurs at a critical fluid velocity corresponding to the shell circumferential mode with the lowest natural frequency. Critical fluid velocities are lower than that of equivalent cylindrical shells. This result holds good for all boundary conditions.
NONLINEAR STABILITY ANALYIS OF THIN SHELL WITH INITIAL SHAPE IMPERFECTIONS
Directory of Open Access Journals (Sweden)
Bazhenov V.A.
2015-12-01
Full Text Available A numerical technique for nonlinear stability analysis of thin-walled shells with geometrical imperfections is presented. Mathematical models of imperfect shells stability are built using the modern finite element method software. The nonlinear stability analysis of a real cylindrical shell with shape imperfections was carried out. Stability domains and reliability of the imperfect shell-bearing under the combined loading were determined.
Evanescent channels and scattering in cylindrical nanowire heterostructures
Racec, P. N.; Racec, E. R.; Neidhardt, H.
2009-04-01
We investigate the scattering phenomena produced by a general finite-range nonseparable potential in a multichannel two-probe cylindrical nanowire heterostructure. The multichannel current scattering matrix is efficiently computed using the R -matrix formalism extended for cylindrical coordinates. Considering the contribution of the evanescent channels to the scattering matrix, we are able to put in evidence the specific dips in the tunneling coefficient in the case of an attractive potential. The cylindrical symmetry cancels the “selection rules” known for Cartesian coordinates. If the attractive potential is superposed over a nonuniform potential along the nanowire then resonant transmission peaks appear. We can characterize them quantitatively through the poles of the current scattering matrix. Detailed maps of the localization probability density sustain the physical interpretation of the resonances (dips and peaks). Our formalism is applied to a variety of model systems such as a quantum dot, a core/shell quantum ring, or a double barrier embedded into the nanocylinder.
Directory of Open Access Journals (Sweden)
Salvatore Brischetto
2014-01-01
equilibrium written in orthogonal curvilinear coordinates for the free vibrations of simply supported structures. These equations consider an exact geometry for shells without simplifications. The main novelty is the possibility of a general formulation for different geometries. The equations written in general orthogonal curvilinear coordinates allow the analysis of spherical shell panels and they automatically degenerate into cylindrical shell panel, cylindrical closed shell, and plate cases. Results are proposed for isotropic and orthotropic structures. An exhaustive overview is given of the vibration modes for a number of thickness ratios, imposed wave numbers, geometries, embedded materials, and angles of orthotropy. These results can also be used as reference solutions to validate two-dimensional models for plates and shells in both analytical and numerical form (e.g., closed solutions, finite element method, differential quadrature method, and global collocation method.
THE METHOD OF LINES IN A CYLINDRICAL COORDINATE SYSTEM
Directory of Open Access Journals (Sweden)
Levkivskiy D.V.
2014-12-01
Full Text Available In this paper the plane strain thick cylindrical shell is rigidly attached to the side faces. To reduce the dimension of initial differential equation method is used in combination with the direct projection of the Bubnov-Galerkin-Petrov. As a result of the reduction equations are reduced to a system of homogeneous first order differential equations in partial derivatives. In the future, the system is solved numerically using the method of discrete orthogonalization S.K.Hodunova.
Effective thermoelastic properties of composites with periodicity in cylindrical coordinates
Chatzigeorgiou, George
2012-09-01
The aim of this work is to study composites that present cylindrical periodicity in the microstructure. The effective thermomechanical properties of these composites are identified using a modified version of the asymptotic expansion homogenization method, which accounts for unit cells with shell shape. The microscale response is also shown. Several numerical examples demonstrate the use of the proposed approach, which is validated by other micromechanics methods. © 2012 Elsevier Ltd. All rights reserved.
Harte, John
Cylindrical Cow will help students achieve a whole new level of environmental modeling and problem solving.Â Featuring a new core set of 25 fully worked-out problems, this book uses real problems in environmental science rather than relying on the more traditional cookbook problems found in textbooks.Â It is organized according to five thematic sections on probability, optimization, scaling, differential equations, and stability & feedback. Each section begins with a general treatment of the relevant mathematical concepts, and concludes with a range of homework exercises to help students sharpen their modeling skills. Like its predecessor, this book will empower students with the mathematical skills needed to cut through the complexity of real-world problems.
Polymers under Cylindrical Confinement
Russell, Thomas
2009-03-01
Anodized alumina oxide (AAO) membranes offer a unique platform to investigate polymers under confinement. AAO membranes have been prepared where the diameters of the nanopores in the membrane have been varied from 8 to 50 nm by varying the anodization conditions. Capillary force is sufficiently large to draw high molecular weight polymers into the membrane, producing either nanotubes or nanorods. Polymer solutions can also be used place a thin film on the walls of the nanopores, forming nanotubes. With pore diameters less than the radius of gyration, a quantitative understanding of perturbations to chain dynamics due to geometric constraints was examined. We found a weak molecular weight-dependent mobility of polymers confined within AAO nanopores having diameters smaller than the dimension of the chains in the bulk. The measured mobility of polymers in the confined geometry was much higher than the mobility of the unconfined chain. Rayleigh instabilities in thin polymer films confined within nanoporous alumina membranes were also found where periodic undulations on the film surface were found to increase with time, eventually bridging across the cylindrical nanopore, resulting in the formation of polymer nanorods with a periodic array of encapsulated holes. With microphase separated block copolymers, where the characteristic period of the BCP morphology is comparable to the pore diameter, significant deviations from the bulk morphology as revealed by electron tomography. Small angle neutron scattering was also used to investigate the influence of cylindrical confinement on the order-to-disordered transition. This work was done in collaboration with T. J. McCarthy (UMass), K. Shin (Seoul National University), H. Jinnai (Kyoto University), D. Chen, J. Chen, H. Xiang, T. Kim, and P. Dobriyal, and was supported by the DOE, NSF MRSEC, NSF CHM.
Stage Cylindrical Immersive Display
Abramyan, Lucy; Norris, Jeffrey S.; Powell, Mark W.; Mittman, David S.; Shams, Khawaja S.
2011-01-01
Panoramic images with a wide field of view intend to provide a better understanding of an environment by placing objects of the environment on one seamless image. However, understanding the sizes and relative positions of the objects in a panorama is not intuitive and prone to errors because the field of view is unnatural to human perception. Scientists are often faced with the difficult task of interpreting the sizes and relative positions of objects in an environment when viewing an image of the environment on computer monitors or prints. A panorama can display an object that appears to be to the right of the viewer when it is, in fact, behind the viewer. This misinterpretation can be very costly, especially when the environment is remote and/or only accessible by unmanned vehicles. A 270 cylindrical display has been developed that surrounds the viewer with carefully calibrated panoramic imagery that correctly engages their natural kinesthetic senses and provides a more accurate awareness of the environment. The cylindrical immersive display offers a more natural window to the environment than a standard cubic CAVE (Cave Automatic Virtual Environment), and the geometry allows multiple collocated users to simultaneously view data and share important decision-making tasks. A CAVE is an immersive virtual reality environment that allows one or more users to absorb themselves in a virtual environment. A common CAVE setup is a room-sized cube where the cube sides act as projection planes. By nature, all cubic CAVEs face a problem with edge matching at edges and corners of the display. Modern immersive displays have found ways to minimize seams by creating very tight edges, and rely on the user to ignore the seam. One significant deficiency of flat-walled CAVEs is that the sense of orientation and perspective within the scene is broken across adjacent walls. On any single wall, parallel lines properly converge at their vanishing point as they should, and the sense of
Flow and scour around vertical submerged structures
Indian Academy of Sciences (India)
Although past investigations establish the effect of various parameters on scour around vertical submerged structures for live and clear water condition, yet further studies are required to analyze the scour around group of submerged structures for various bed sediments, understand the flow physics around the group and ...
Experimental investigations on buckling of cylindrical shells under ...
Indian Academy of Sciences (India)
R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22
experimentally to validate the design. Keeping this in mind, a test programme has been for- mulated at the Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam to carry out experimental studies on ..... mounting the specimen on the test bed with all its instrumentation, firstly the imperfection survey is carried out.
Analysis of radial vibrations of poroelastic circular cylindrical shells ...
African Journals Online (AJOL)
DR OKE
2*Department of Mathematics, Deccan College of Engineering and Technology, Hyderabad, INDIA. 3 Department ... Introduction. The study of propagation of waves is important in different fields of engineering and geophysics, particularly in the area of ...... International Journal of Applied Mathematics and Mechanics. Vol.9 ...
Analysis of radial vibrations of poroelastic circular cylindrical shells ...
African Journals Online (AJOL)
DR OKE
Gazis (1959) discussed the propagation of free harmonic waves along a hollow elastic circular cylinder of infinite extent and solved the frequency equation ... The coefficient Q represents the coupling between the volume change of the ... can readily be evaluated for steady state harmonic vibrations from equations (1) are.
Higher-Order Thickness Expansions for Cylindrical Shells
1991-09-01
Engblom, John J. and 0. 0. Ochoa. "Finite Element Formulation Including Inter - laminar Stress Calculations," Computers & Structures, 23: No. 2, 241-249... Teoria Plyt Sredniej Grubbosci (Technical Theory of Plates with Moderate Thickness)," Rozprawy Inzynierskie (English Translation, Pol- ska Akademia Nauk
static analysis of circular cylindrical shell under hydrostatic and ring ...
African Journals Online (AJOL)
DEPT OF AGRICULTURAL ENGINEERING
elastic foundation, was obtained from static principles on the assumptions of P. L. Pasternak. The initial value method was used to solve the obtained fourth order differential equation for both cases of hydrostatic and ring forces. ... silos, pipelines, bridge arches or wind turbine towers (Winterstetter et al, 2002). This work is.
A Solution Method for Nonlinear Dynamic Analysis of Shell Structures
1984-10-01
continuum mechanics theory and it is applicable to the analysis of thin and thick shells. The formulation of the element and the solutions to...Linear analysis of a cylindrical ( Scordelis -Lo) shell 26 4.3 Linear analysis of a pinched cylinder 26 4.4 Large deflection analysis of a...latter approach has the advantage of being independent of any particular shell theory , and this approach was used in ref. [3] to formulate a general
Thin shells joining local cosmic string geometries
Energy Technology Data Exchange (ETDEWEB)
Eiroa, Ernesto F. [Universidad de Buenos Aires, Ciudad Universitaria Pabellon I, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina); Instituto de Astronomia y Fisica del Espacio (IAFE, CONICET-UBA), Buenos Aires (Argentina); Rubin de Celis, Emilio; Simeone, Claudio [Universidad de Buenos Aires, Ciudad Universitaria Pabellon I, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina); Ciudad Universitaria Pabellon I, IFIBA-CONICET, Buenos Aires (Argentina)
2016-10-15
In this article we present a theoretical construction of spacetimes with a thin shell that joins two different local cosmic string geometries. We study two types of global manifolds, one representing spacetimes with a thin shell surrounding a cosmic string or an empty region with Minkowski metric, and the other corresponding to wormholes which are not symmetric across the throat located at the shell. We analyze the stability of the static configurations under perturbations preserving the cylindrical symmetry. For both types of geometries we find that the static configurations can be stable for suitable values of the parameters. (orig.)
Thin shells joining local cosmic string geometries
Eiroa, Ernesto F; Simeone, Claudio
2016-01-01
In this article we present a theoretical construction of spacetimes with a thin shell that joins two different local cosmic string geometries. We study two types of global manifolds, one representing spacetimes with a standard thin shell and the other corresponding to wormholes which are not symmetric across the throat located at the shell. We analyze the stability of the static configurations under perturbations preserving the cylindrical symmetry. For both types of geometries we find that the static configurations can be stable for suitable values of the parameters.
Iodine Removal Efficiency in Non-Submerged and Submerged Self-Priming Venturi Scrubber
Energy Technology Data Exchange (ETDEWEB)
Ali, Majid; Yan, Changqi; Sun, Zhongning; Gu, Haifeng; Wang, Junlong; Mehboob; Khurram [Harbin Engineering Univ., Harbin (China)
2013-04-15
The objective of this conducted research is to study the iodine removal efficiency in a self-priming venturi scrubber for submerged and non-submerged operating conditions experimentally and theoretically. The alkaline solution is used as an absorbent, which is prepared by dissolving sodium hydroxide (NaOH) and sodium thiosulphate (Na{sub 2}S{sub 2}O{sub 3}) in water to remove the gaseous iodine (I{sub 2}) from the gas. Iodine removal efficiency is examined at various gas flow rates and inlet concentrations of iodine for submerged and non-submerged operating conditions. In the non-submerged venturi scrubber, only the droplets take part in iodine removal efficiency. However, in a submerged venturi scrubber condition, the iodine gas is absorbed from gas to droplets inside the venturi scrubber and from bubbles to surrounding liquid at the outlet of a venturi scrubber. Experimentally, it is observed that the iodine removal efficiency is greater in the submerged venturi scrubber as compare to a non-submerged venturi scrubber condition. The highest iodine removal efficiency of 0.99±0.001 has been achieved in a submerged self-priming venturi scrubber condition. A mathematical correlation is used to predict the theoretical iodine removal efficiency in submerged and non-submerged conditions, and it is compared against the experimental results. The Wilkinson et al. correlation is used to predict the bubble diameter theoretically whereas the Nukiyama and Tanasawa correlation is used for droplet diameter. The mass transfer coefficient for the gas phase is calculated from the Steinberger and Treybal correlation. The calculated results for a submerged venturi scrubber agree well with experimental results but underpredicts in the case of the non-submerged venturi scrubber.
IODINE REMOVAL EFFICIENCY IN NON-SUBMERGED AND SUBMERGED SELF-PRIMING VENTURI SCRUBBER
Directory of Open Access Journals (Sweden)
MAJID ALI
2013-04-01
Full Text Available The objective of this conducted research is to study the iodine removal efficiency in a self-priming venturi scrubber for submerged and non-submerged operating conditions experimentally and theoretically. The alkaline solution is used as an absorbent, which is prepared by dissolving sodium hydroxide (NaOH and sodium thiosulphate (Na2S2O3 in water to remove the gaseous iodine (I2 from the gas. Iodine removal efficiency is examined at various gas flow rates and inlet concentrations of iodine for submerged and non-submerged operating conditions. In the non-submerged venturi scrubber, only the droplets take part in iodine removal efficiency. However, in a submerged venturi scrubber condition, the iodine gas is absorbed from gas to droplets inside the venturi scrubber and from bubbles to surrounding liquid at the outlet of a venturi scrubber. Experimentally, it is observed that the iodine removal efficiency is greater in the submerged venturi scrubber as compare to a non-submerged venturi scrubber condition. The highest iodine removal efficiency of 0.99±0.001 has been achieved in a submerged self-priming venturi scrubber condition. A mathematical correlation is used to predict the theoretical iodine removal efficiency in submerged and non-submerged conditions, and it is compared against the experimental results. The Wilkinson et al. correlation is used to predict the bubble diameter theoretically whereas the Nukiyama and Tanasawa correlation is used for droplet diameter. The mass transfer coefficient for the gas phase is calculated from the Steinberger and Treybal correlation. The calculated results for a submerged venturi scrubber agree well with experimental results but underpredicts in the case of the non-submerged venturi scrubber.
Inflation of stressed cylindrical tubes: an experimental study
Guo, Zhiming; Wang, Shibin; Li, Linan; Ji, Hongwei; Wang, Zhiyong; Cai, Songbao
2014-06-01
The inflation of an initially stressed cylindrical shell provides a good illustration of the phenomenon of the initiation and propagation of an instability, which shares the same mathematical and mechanical features with a variety of other strain localization phenomena in engineering structures and materials. The high speed CCD camera and digital image processing system were used to measure the 3D shape of the inflated cylindrical tube. The localized bulge of a cylindrical tube with closed ends forms when the internal pressure reaches a critical value Pcr. As more air is filled into the tube, the pressure drops but the radius at the centre of the bulge will increase until it reaches a maximum value rmax. With continued inflation, the pressure stays at a constant value Pp. The purpose of this study is to investigate the critical and propagation pressures in the tubes and the profile outside when the shells under axial tension and internal pressure were inflating. We focus on the influence of the axial tension on the critical pressure. In this paper the problem is explored through experimental efforts. A series of experiments were conducted on commercially available natural rubber latex tubes involving different geometries and initial axial tensions, which were regarded as isotropic, homogeneous, incompressible and hyper-elastic materials.
National Research Council Canada - National Science Library
Jumpei YASUNAGA; Choongmo KOO; Yasushi UEMATSU
2012-01-01
Two series of wind tunnel experiments and a finite element analysis are carried out to investigate the buckling behavior of thin cylindrical shell structures, such as open-topped oil-storage tanks...
A peridynamic theory for linear elastic shells
Chowdhury, Shubhankar Roy; Roy, Debasish; Reddy, J N
2015-01-01
A state-based peridynamic formulation for linear elastic shells is presented. The emphasis is on introducing, possibly for the first time, a general surface based peridynamic model to represent the deformation characteristics of structures that have one physical dimension much smaller than the other two. A new notion of curved bonds is exploited to cater for force transfer between the peridynamic particles describing the shell. Starting with the three dimensional force and deformation states, appropriate surface based force, moment and several deformation states are arrived at. Upon application on the curved bonds, such states beget the necessary force and deformation vectors governing the motion of the shell. Correctness of our proposal on the peridynamic shell theory is numerically assessed against static deformation of spherical and cylindrical shells and flat plates.
Structural shell analysis understanding and application
Blaauwendraad, Johan
2014-01-01
The mathematical description of the properties of a shell is much more elaborate than those of beam and plate structures. Therefore many engineers and architects are unacquainted with aspects of shell behaviour and design, and are not familiar with sufficiently reliable shell theories for the different shell types as derived in the middle of the 20th century. Rather than contributing to theory development, this university textbook focuses on architectural and civil engineering schools. Of course, practising professionals will profit from it as well. The book deals with thin elastic shells, in particular with cylindrical, conical and spherical types, and with elliptic and hyperbolic paraboloids. The focus is on roofs, chimneys, pressure vessels and storage tanks. Special attention is paid to edge bending disturbance zones, which is indispensable knowledge in FE meshing. A substantial part of the book results from research efforts in the mid 20th century at Delft University of Technology. As such, it is a valua...
Telescoping cylindrical piezoelectric fiber composite actuator assemblies
Allison, Sidney G. (Inventor); Shams, Qamar A. (Inventor); Fox, Robert L. (Inventor); Fox, legal representative, Christopher L. (Inventor); Fox Chattin, legal representative, Melanie L. (Inventor)
2010-01-01
A telescoping actuator assembly includes a plurality of cylindrical actuators in a concentric arrangement. Each cylindrical actuator is at least one piezoelectric fiber composite actuator having a plurality of piezoelectric fibers extending parallel to one another and to the concentric arrangement's longitudinal axis. Each cylindrical actuator is coupled to concentrically-adjacent ones of the cylindrical actuators such that the plurality of cylindrical actuators can experience telescopic movement. An electrical energy source coupled to the cylindrical actuators applies actuation energy thereto to generate the telescopic movement.
THE STRUCTURAL ANALYSIS OF STEEL SILOS WITH CYLINDRICAL-WALL BEARING AND PROFILE-STEEL BEARING
Directory of Open Access Journals (Sweden)
Zhengjun Tang
2015-04-01
Full Text Available The silos are widely used in bulk material in many fields such as agriculture, mining, chemical, electric power storage, etc. Thin metal cylindrical silo shells are vulnerable to buckling failure caused by the compressive wall friction force. In this paper, the structural analysis of two types of steel silo with cylindrical-wall bearing and profile-steel bearing is implemented by Abaqus finite element analysis. The results indicate that under the same loading conditions, steel silos with profile-steel bearing and cylindrical-Wall bearing have similar values in Mises stress, but the steel silo with profile-steel bearing has a smaller radial displacement and a better capability of buckling resistance. Meanwhile, the total steel volumes reduced 8.0% comparing to the steel silo with cylindrical-wall bearing. Therefore, steel soil with profile-steel bearing not only has a less steel volumes but also a good stability.
Optics Demonstrations Using Cylindrical Lenses
Ivanov, Dragia; Nikolov, Stefan
2015-01-01
In this paper we consider the main properties of cylindrical lenses and propose several demonstrational experiments that can be performed with them. Specifically we use simple glasses full of water to demonstrate some basic geometrical optics principles and phenomena. We also present some less standard experiments that can be performed with such…
DEFF Research Database (Denmark)
Almegaard, Henrik
2004-01-01
A new statical and conceptual model for membrane shell structures - the stringer system - has been found. The principle was first published at the IASS conference in Copenhagen (OHL91), and later the theory has been further developed (ALMO3)(ALMO4). From the analysis of the stringer model it can...... be concluded that all membrane shells can be described by a limited number of basic configurations of which quite a few have free edges....
Impeller Submergence Depth for Stirred Tanks
Directory of Open Access Journals (Sweden)
Thiyam T. Devi
2011-11-01
Full Text Available Impeller submergence governs the performance of mixing tanks employed in oxygen transfer operation. Present work experimentally investigates the effect of impeller submergence depths on oxygen transfer and corresponding power consumption. It has been found that at higher range of impeller submergence, mixing tanks consume less power and gives higher values of oxygen transfer coefficient. Optimal range of submergence depth is 0.7 to 0.9 times the impeller diameter. Copyright ©2011 BCREC UNDIP. All rights reserved.(Received: 4th March 2011; Revised: 12nd July 2011; Accepted: 14th July 2011[How to Cite: T.T. Devi, A.P. Sinha, M. Thakre, and B. Kumar. (2011. Impeller Submergence Depth for Stirred Tanks. Bulletin of Chemical Reaction Engineering & Catalysis, 6 (2: 123-128. doi:10.9767/bcrec.6.2.826.123-128][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.6.2.826.123-128 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/826] | View in
Cloaking by shells with radially inhomogeneous anisotropic permittivity.
Reshetnyak, V Yu; Pinkevych, I P; Sluckin, T J; Evans, D R
2016-01-25
We model electromagnetic cloaking of a spherical or cylindrical nanoparticle enclosed by an optically anisotropic and optically inhomogeneous symmetric shell, by examining its electric response in a quasi-static uniform electric field. When the components of the shell permittivity are radially anisotropic and power-law dependent (ε~r(m)) whereris distance to the shell center, and m a positive or negative exponent which can be varied), the problem is analytically tractable. Formulas are calculated for the degree of cloaking in the general case, allowing the determination of a dielectric condition for the shells to be used as an invisibility cloak. Ideal cloaking is known to require that homogeneous shells exhibit an infinite ratio of tangential and radial components of the shell permittivity, but for radially inhomogeneous shells ideal cloaking can occur even for finite values of this ratio.
Strength Calculation of Locally Loaded Orthotropic Shells
Directory of Open Access Journals (Sweden)
Yu. I. Vinogradov
2015-01-01
Full Text Available The article studies laminated orthotropic cylindrical, conic, spherical, and toroidal shells, which are often locally loaded in the aircraft designs over small areas of their surfaces.The aim of this work is to determine stress concentration in shells versus structure of orthotropic composite material, shell form and parameters, forms of loading areas, which borders do not coincide with lines of main curvatures of shells. For this purpose, an analytical computing algorithm to estimate strength of shells in terms of stress is developed. It enables us to have solution results of the boundary value problem with a controlled error. To solve differential equations an analytical method is used. An algorithm of the boundary value problem solution is multiplicative.The main results of researches are graphs of stress concentration in the orthotropic shells versus their parameters and areas of loading lineated by circles and ellipses.Among the other works aimed at determination of stress concentration in shells, the place of this one is defined by the analytical solution of applied problems for strength estimation in terms of shell stresses of classical forms.The developed effective analytical algorithm to solve the boundary value problem and received results are useful in research and development.
Waves on fluid-loaded shells and their resonance frequency spectrum
DEFF Research Database (Denmark)
Bao, X.L.; Uberall, H.; Raju, P.K.
2005-01-01
Technical requirements for elastic (metal) cylindrical shells include the knowledge of their natural frequency spectrum. These shells may be empty and fluid-immersed, or fluid-filled in an ambient medium of air, or doubly fluid-loaded inside and out. They may support circumferential waves......, or axially propagating waves both in the shell material, and in the fluid loading. Previous results by Bao et al. (J. Acoust. Soc. Am. 105 (1999) 2704) were obtained for the circumferential-wave dispersion curves on doubly loaded aluminum shells; the present study extends this to fluid-filled shells in air....... For practical applications, steel shells are most important and we have here obtained corresponding results for these. To find the natural frequencies of cylindrical shells, one may invoke the principle of phase matching where resonating standing waves are formed around the circumference, or in the axial...
Cracking of anisotropic cylindrical polytropes
Energy Technology Data Exchange (ETDEWEB)
Mardan, S.A. [University of the Management and Technology, Department of Mathematics, Lahore (Pakistan); Azam, M. [University of Education, Division of Science and Technology, Lahore (Pakistan)
2017-06-15
We study the appearance of cracking in charged anisotropic cylindrical polytropes with generalized polytropic equation. We investigate the existence of cracking in two different kinds of polytropes existing in the literature through two different assumptions: (a) local density perturbation with conformally flat condition, and (b) perturbing polytropic index, charge and anisotropy parameters. We conclude that cracking appears in both kinds of polytropes for a specific range of density and model parameters. (orig.)
Laser Beam Submerged Arc Hybrid Welding
Reisgen, Uwe; Olschok, Simon; Jakobs, Stefan; Schleser, Markus; Mokrov, Oleg; Rossiter, Eduardo
The laser beam-submerged arc hybrid welding method originates from the knowledge that, with increasing penetration depth, the laser beam process has a tendency to pore formation in the lower weld regions. The coupling with the energy-efficient submerged-arc process improves degassing and reduces the tendency to pore formation. The high deposition rate of the SA process in combination with the laser beam process offers, providing the appropriate choice of weld preparation, the possibility of welding plates with a thickness larger than 20° mm in a single pass, and also of welding thicker plates with the double-sided single pass technique.
Implosion of Cylindrical Cavities via Short Duration Impulsive Loading
Huneault, Justin; Higgins, Andrew
2014-11-01
An apparatus has been developed to study the collapse of a cylindrical cavity in gelatin subjected to a symmetric impact-driven impulsive loading. A gas-driven annular projectile is accelerated to approximately 50 m/s, at which point it impacts a gelatin casting confined by curved steel surfaces that allow a transition from an annular geometry to a cylindrically imploding motion. The implosion is visualized by a high-speed camera through a window which forms the top confining wall of the implosion cavity. The initial size of the cavity is such that the gelatin wall is two to five times thicker than the impacting projectile. Thus, during impact the compression wave which travels towards the cavity is closely followed by a rarefaction resulting from the free surface reflection of the compression wave in the projectile. As the compression wave in the gelatin reaches the inner surface, it will also reflect as a rarefaction wave. The interaction between the rarefaction waves from the gelatin and projectile free surfaces leads to large tensile stresses resulting in the spallation of a relatively thin shell. The study focuses on the effect of impact parameters on the thickness and uniformity of the imploding shell formed by the cavitation in the imploding gelatin cylinder.
Cylindrical Piezoelectric Fiber Composite Actuators
Allison, Sidney G.; Shams, Qamar A.; Fox, Robert L.
2008-01-01
The use of piezoelectric devices has become widespread since Pierre and Jacques Curie discovered the piezoelectric effect in 1880. Examples of current applications of piezoelectric devices include ultrasonic transducers, micro-positioning devices, buzzers, strain sensors, and clocks. The invention of such lightweight, relatively inexpensive piezoceramic-fiber-composite actuators as macro fiber composite (MFC) actuators has made it possible to obtain strains and displacements greater than those that could be generated by prior actuators based on monolithic piezoceramic sheet materials. MFC actuators are flat, flexible actuators designed for bonding to structures to apply or detect strains. Bonding multiple layers of MFC actuators together could increase force capability, but not strain or displacement capability. Cylindrical piezoelectric fiber composite (CPFC) actuators have been invented as alternatives to MFC actuators for applications in which greater forces and/or strains or displacements may be required. In essence, a CPFC actuator is an MFC or other piezoceramic fiber composite actuator fabricated in a cylindrical instead of its conventional flat shape. Cylindrical is used here in the general sense, encompassing shapes that can have circular, elliptical, rectangular or other cross-sectional shapes in the planes perpendicular to their longitudinal axes.
Multielement stoichiometry of submerged macrophytes across Yunnan plateau lakes (China)
National Research Council Canada - National Science Library
Xing, Wei; Wu, Haoping; Shi, Qiao; Hao, Beibei; Liu, Han; Wang, Zhixiu; Liu, Guihua
2015-01-01
.... We predicted that tissue element composition in submerged macrophytes is affected by lake trophic level and taxonomy, and submerged macrophytes have weak stoichiometric homeostasis for all above 16 elements...
Oxygen dynamics in submerged rice (Oryza sativa L.)
DEFF Research Database (Denmark)
Colmer, Timothy D.; Pedersen, Ole
2008-01-01
Complete submergence of plants prevents direct O2 and CO2 exchange with air. Underwater photosynthesis can result in marked diurnal changes in O2 supply to submerged plants. Dynamics in pO2 had not been measured directly for submerged rice (Oryza sativa), but in an earlier study, radial O2 loss...
Design and optimization of the large span dry-coal-shed latticed shell in Liyuan of Henan province
Directory of Open Access Journals (Sweden)
Du Wenfeng
2017-01-01
Full Text Available The design and optimization about the large span dry-coal-shed latticed shell in Liyuan of Henan province were studied. On the basis of the structural scheme of double-layer cylindrical reticulated shell, the optimization scheme of the folding double-layer cylindrical reticulated shell was proposed. Through the analysis of a plurality of calculation models, the optimal geometric parameters were obtained after discussing the influence of different slopes of folding lines and shell thickness on the structural bearing capacity and the amount of steel. The research results show that in the case of the same amount of steel, the ultimate bearing capacity of the double-layer folding cylindrical reticulated shell whose folding line slope is 9% and the shell thickness is about 4.4m can be increased 27.3% compared with the original design scheme.
Benthic bacterial diversity in submerged sinkhole ecosystems.
Nold, Stephen C; Pangborn, Joseph B; Zajack, Heidi A; Kendall, Scott T; Rediske, Richard R; Biddanda, Bopaiah A
2010-01-01
Physicochemical characterization, automated ribosomal intergenic spacer analysis (ARISA) community profiling, and 16S rRNA gene sequencing approaches were used to study bacterial communities inhabiting submerged Lake Huron sinkholes inundated with hypoxic, sulfate-rich groundwater. Photosynthetic cyanobacterial mats on the sediment surface were dominated by Phormidium autumnale, while deeper, organically rich sediments contained diverse and active bacterial communities.
Production of extracellular aspartic protease in submerged ...
African Journals Online (AJOL)
Yomi
29(1): 1-6. Fraile ER, Bernardinelli SE, Handel M, Jauregui AM (1978). Selección de cepas de Mucor sp productoras de enzimas coagulantes de leche. Rev. Arg. Microbiol. 10(2): 65-69. Ghareib M, Hamdy HS, Khalil AA (2001). Production of intracellular milk clotting enzyme in submerged cultures of Fusarium subglutinans.
Topology optimization for submerged buoyant structures
Picelli, R.; van Dijk, R.; Vicente, W.M.; Pavanello, R.; Langelaar, M.; van Keulen, A.
2017-01-01
This paper presents an evolutionary structural topology optimization method for the design of completely submerged buoyant modules with design-dependent fluid pressure loading. This type of structure is used to support offshore rig installation and pipeline transportation at all water depths. The
Production of extracellular aspartic protease in submerged ...
African Journals Online (AJOL)
Fungal milk-clotting enzymes have gained value as bovine Chymosin substitutes in the cheese industry. In this work, the effects of culture conditions on the production of extracellular milk clotting enzymes from Mucor mucedo DSM 809 in submerged fermentation were studied. The maximum activity was observed after 48 h ...
An asymptotically exact theory of functionally graded piezoelectric shells
Le, Khanh Chau
2016-01-01
An asymptotically exact two-dimensional theory of functionally graded piezoelectric shells is derived by the variational-asymptotic method. The error estimation of the constructed theory is given in the energetic norm. As an application, analytical solution to the problem of forced vibration of a functionally graded piezoceramic cylindrical shell with thickness polarization fully covered by electrodes and excited by a harmonic voltage is found.
Thickness mapping of submerged portions of a BWR torus using an ROV
Energy Technology Data Exchange (ETDEWEB)
Somers, T. (Marquest Group, Inc., Bourne, MA (United States)); Bagley, J.G. (Ebasco Quality Services, South Kearny, NJ (United States))
1992-01-01
A methodology has been developed for establishing an ultrasonic baseline of the submerged portions of a boiling water reactor torus shell. A remotely operated vehicle (ROV) is equipped to deliver an array of ultrasonic thickness transducers to within a fixed stand-off from the shell. The position of the transducers at each ultrasound reading is measured and recorded using a precision acoustic navigation system. The resulting thickness contour map makes it possible to visualize the condition of the torus shell and provides quantitative documentation of shell thickness at a large number of known locations. The navigation system can be reinstalled in the future so that by comparing future thickness readings acquired at the same location, it is possible to create a map of the rate of change in shell thickness. An ultrasonic thickness survey was conducted recently using a preliminary version of such a system. The experience gained in performing this survey has been incorporated in the design of a full-scale prototype system, which is currently under development. This system will include such features as automatic control of the ROV based on the acoustic navigation data, generation of three-dimensional thickness maps, and remote control of the data acquisition process from outside the radiation area.
Modelling apical constriction in epithelia using elastic shell theory.
Jones, Gareth Wyn; Chapman, S Jonathan
2010-06-01
Apical constriction is one of the fundamental mechanisms by which embryonic tissue is deformed, giving rise to the shape and form of the fully-developed organism. The mechanism involves a contraction of fibres embedded in the apical side of epithelial tissues, leading to an invagination or folding of the cell sheet. In this article the phenomenon is modelled mechanically by describing the epithelial sheet as an elastic shell, which contains a surface representing the continuous mesh formed from the embedded fibres. Allowing this mesh to contract, an enhanced shell theory is developed in which the stiffness and bending tensors of the shell are modified to include the fibres' stiffness, and in which the active effects of the contraction appear as body forces in the shell equilibrium equations. Numerical examples are presented at the end, including the bending of a plate and a cylindrical shell (modelling neurulation) and the invagination of a spherical shell (modelling simple gastrulation).
Multidisciplinary optimization of a stiffened shell by genetic algorithm
Energy Technology Data Exchange (ETDEWEB)
Mehrabani, Mahdi Maghsoudi; Jafari, Ali Asghar [K.N. Toosi University of Technology, Tehran (Iran, Islamic Republic of); Azadi, Mohammad [Sharif University of Technology, Tehran (Iran, Islamic Republic of)
2012-02-15
Vibration analysis of simply supported rotating cross-ply laminated stiffened cylindrical shell is performed using an energy approach which includes variational and averaging method. The stiffeners include rings and stringers. The equations are obtained by Rayleigh-Ritz method and Sander's relations. To validate the present method, the results are compared to the results available in other literatures. A good adoption is observed in different type of results including isotropic shells, rotating laminated shells, stiffened isotropic shells and stiffened laminated shells. Then, the optimization of parameters due to shell and stiffeners is conducted by genetic algorithm (GA) method under weight and frequency constraints. Stiffener shape, material properties and dimensions are also optimized.
Dynamics of Inhomogeneous Shell Systems Under Non-Stationary Loading (Survey)
Lugovoi, P. Z.; Meish, V. F.
2017-09-01
Experimental works on the determination of dynamics of smooth and stiffened cylindrical shells contacting with a soil medium under various non-stationary loading are reviewed. The results of studying three-layer shells of revolution whose motion equations are obtained within the framework of the hypotheses of the Timoshenko geometrically nonlinear theory are stated. The numerical results for shells with a piecewise or discrete filler enable the analysis of estimation of the influence of geometrical and physical-mechanical parameters of structures on their dynamics and reveal new mechanical effects. Basing on the classical theory of shells and rods, the effect of the discrete arrangement of ribs and coefficients of the Winkler or Pasternak elastic foundation on the normal frequencies and modes of rectangular planar cylindrical and spherical shells is studied. The number and shape of dispersion curves for longitudinal harmonic waves in a stiffened cylindrical shell are determined. The equations of vibrations of ribbed shells of revolution on Winkler or Pasternak elastic foundation are obtained using the geometrically nonlinear theory and the Timoshenko hypotheses. On applying the integral-interpolational method, numerical algorithms are developed and the corresponding non-stationary problems are solved. The special attention is paid to the statement and solution of coupled problems on the dynamical interaction of cylindrical or spherical shells with the soil water-saturated medium of different structure.
Parallel Control to Fragments of a Cylindrical Structure Driven by Explosive inside
Directory of Open Access Journals (Sweden)
Wenkai Chen
2015-01-01
Full Text Available By analyzing the fragmentation distributions of a cylindrical structure and a specific structure, the necessity of parallel control to the fragments is presented. The shell shape of structures has an influence on the fragment spatial distribution. A new design method for the shell shape is proposed. To facilitate the establishment of the numerical model and the machining for relative experiments, the mathematical description of the theoretical calculated generatrix of the shell is simplified. The fragment spraying processes of the designed structures are simulated, and end effects are analyzed. Based on the theoretical design and plentiful simulation data, the relationships between the size of the parallel fragmentation structure and the optimized curvature radius of the shell are expressed by an equation. The equation is validated by numerical means and can be a reliable reference to the design of the parallel fragmentation structure.
Hilburger, Mark W.; Starnes, James H., Jr.
2004-01-01
The results of a parametric study of the effects of initial imperfections on the buckling and postbuckling response of three unstiffened thinwalled compression-loaded graphite-epoxy cylindrical shells with different orthotropic and quasi-isotropic shell-wall laminates are presented. The imperfections considered include initial geometric shell-wall midsurface imperfections, shell-wall thickness variations, local shell-wall ply-gaps associated with the fabrication process, shell-end geometric imperfections, nonuniform applied end loads, and variations in the boundary conditions including the effects of elastic boundary conditions. A high-fidelity nonlinear shell analysis procedure that accurately accounts for the effects of these imperfections on the nonlinear responses and buckling loads of the shells is described. The analysis procedure includes a nonlinear static analysis that predicts stable response characteristics of the shells and a nonlinear transient analysis that predicts unstable response characteristics.
Models of cylindrical bubble pulsation
Ilinskii, Yurii A.; Zabolotskaya, Evgenia A.; Hay, Todd A.; Hamilton, Mark F.
2012-01-01
Three models are considered for describing the dynamics of a pulsating cylindrical bubble. A linear solution is derived for a cylindrical bubble in an infinite compressible liquid. The solution accounts for losses due to viscosity, heat conduction, and acoustic radiation. It reveals that radiation is the dominant loss mechanism, and that it is 22 times greater than for a spherical bubble of the same radius. The predicted resonance frequency provides a basis of comparison for limiting forms of other models. The second model considered is a commonly used equation in Rayleigh-Plesset form that requires an incompressible liquid to be finite in extent in order for bubble pulsation to occur. The radial extent of the liquid becomes a fitting parameter, and it is found that considerably different values of the parameter are required for modeling inertial motion versus acoustical oscillations. The third model was developed by V. K. Kedrinskii [Hydrodynamics of Explosion (Springer, New York, 2005), pp. 23–26] in the form of the Gilmore equation for compressible liquids of infinite extent. While the correct resonance frequency and loss factor are not recovered from this model in the linear approximation, it provides reasonable agreement with observations of inertial motion. PMID:22978863
CSIR Research Space (South Africa)
Jule, L
2015-07-01
Full Text Available We investigate light scattering by core–shell consisting of metal/dielectric composites considering spherical and cylindrical nanoinclusions, within the framework of the conventional Rayleigh approximation. By writing the electric potential...
Roy, Kenneth I.; Kennedy, Robert G., III; Fields, David E.
2013-02-01
The traditional concept of terraforming assumes ready availability of candidate planets with acceptable qualities: orbiting a star in its "Goldilocks zone", liquid water, enough mass, years longer than days, magnetic field, etc. But even stipulating affordable interstellar travel, we still might never find a good candidate elsewhere. Whatever we found likely would require centuries of heavy terraforming, just as Mars or Venus would here. Our increasing appreciation of the ubiquity of life suggests that any terra nova would already possess it. We would then face the dilemma of introducing alien life forms (us, our microbes) into another living world. Instead, we propose a novel method to create habitable environments for humanity by enclosing airless, sterile, otherwise useless planets, moons, and even large asteroids within engineered shells, which avoids the conundrum. These shells are subject to two opposing internal stresses: compression due to the primary's gravity, and tension from atmospheric pressure contained inside. By careful design, these two cancel each other resulting in zero net shell stress. Beneath the shell an Earth-like environment could be created similar in almost all respects to that of Home, except for gravity, regardless of the distance to the sun or other star. Englobing a small planet, moon, or even a dwarf planet like Ceres, would require astronomical amounts of material (quadrillions of tons) and energy, plus a great deal of time. It would be a quantum leap in difficulty over building Dyson Dots or industrializing our solar system, perhaps comparable to a mission across interstellar space with a living crew within their lifetime. But when accomplished, these constructs would be complete (albeit small) worlds, not merely large habitats. They could be stable across historic timescales, possibly geologic. Each would contain a full, self-sustaining ecology, which might evolve in curious directions over time. This has interesting implications
Role of Genome in the Formation of Conical Retroviral Shells
Erdemci-Tandogan, Gonca; Wagner, Jef; Schoot, Paul van der; Zandi, Roya
2016-01-01
Human immunodeficiency virus (HIV) capsid proteins spontaneously assemble around the genome into a protective protein shell called the capsid, which can take on a variety of shapes broadly classified as conical, cylindrical and irregular. The majority of capsids seen in in vivo studies are conical
Pump Coastdown with the Submerged Flywheel
Energy Technology Data Exchange (ETDEWEB)
Yoon, Hyun-Gi; Seo, KyoungWoo; Kim, Seong Hoon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2016-10-15
Many research reactors are generally designed as open pool types in consideration of the heat removal of the nuclear fuels, reactor operation and accessibility. Reactor structure assembly is generally placed at the pool bottom as shown in Fig. 1. Primary cooling system pump circulates the coolant from the reactor structure to the heat exchanger in order to continuously remove the heat generated from the reactor core in the research reactor as shown in Fig. 1. The secondary cooling system releases the transferred heat to the atmosphere by the cooling tower. Coastdown flow rate of the primary cooling system pump with the submerged flywheel are calculated analytically in case of the accident situation. Coastdown flow rate is maintained until almost 80 sec when the pump stops normally. But, coastdown flow rate is rapidly decreased when the flywheel is submerged because of the friction load on the flywheel surface.
Coastline Protection by a Submerged Breakwater
Valentine, B. D.; Hayatdavoodi, M.; Ertekin, R. C.
2016-02-01
Coastal communities are in danger of the impact caused by storm surge and waves. Storm surge brings the water level to a higher elevation and farther inland. This rise in water level increases the chance of a higher number and larger set of waves approaching shorelines, and it can potentially devastate the coastal infrastructure. In this study, we evaluate the performance of a submerged, horizontal breakwater located near shore. Unlike other types of breakwaters, such as the ones that extend to the surface, either fixed or floating, a submerged horizontal breakwater does not create any visual distraction or limit most of the recreational and commercial activities in the nearshore areas. The Level I Green-Naghdi (GN) nonlinear water wave equations are utilized here to study the wave transformation over a submerged breakwater that is located in shallow water. The GN theory is based on the theory of directed fluid sheets and assumes an incompressible and inviscid fluid; no assumption on the rotationality of the flow is required. In this approach, the nonlinear boundary conditions and the averaged conservation laws are satisfied exactly. The reflection and transmission coefficients due to nonlinear shallow water waves are determined implementing two approaches which use Goda's (1976) and Grue's (1992) methods. The results are compared with the existing laboratory experiments, and close agreement is observed overall. Preliminary results of the performance of the breakwater on dissipating storm waves during Hurricane Ike (2008), approaching the shore of Galveston, Texas, are presented.
Weyl fermions in cylindrical wires
Erementchouk, Mikhail; Mazumder, Pinaki
2018-01-01
The key feature of Weyl semimetals (WSMs) is the presence of topologically protected Dirac cones in a three-dimensional material. We consider the effect of restricting geometry on the spectrum of excitations in WSMs using as a model a cylindrical WSM wire. For the full manifold of hard boundary conditions, we derive the general form of the dispersion equation relating the energy of the excitations and their momentum along the wire. We show that only the special class of boundary conditions, corresponding to decoupled helicities or, equivalently, to pinned directions of the electron spin on the surface, support massless excitations. For a general boundary condition, these excitations acquire mass inversely proportional to the radius of the wire. This demonstrates that boundary phenomena may play a crucial role in formation of excitations in WSM based structures.
Magnetic guns with cylindrical permanent magnets
DEFF Research Database (Denmark)
Vokoun, David; Beleggia, Marco; Heller, Luděk
2012-01-01
The motion of a cylindrical permanent magnet (projectile) inside a tubular permanent magnet, with both magnets magnetized axially, illustrates nicely the physical principles behind the operation of magnetic guns. The force acting upon the projectile is expressed semi-analytically as derivative...... forces and motion of the inner cylindrical magnet....
On cylindrical near-field scanning techniques
DEFF Research Database (Denmark)
Appel-Hansen, Jørgen
1980-01-01
The agreement between the coupling equations obtained in the literature by using the reciprocity theorem and the scattering matrix formulation is demonstrated. The field is expanded in cylindrical vector wave functions and the addition theorem for these functions is used. The communication may se...... serve as a tutorial introduction to the cylindrical scanning techniques....
Polymer Dynamics under Cylindrical Nano-Confinement
Winey, Karen; Tung, Wei-Shao; Riggleman, Robert
2015-03-01
Polymer melts under cylindrical confinement have previously been shown to exhibit chain conformations elongated parallel to the cylinder axis and compressed perpendicular to the cylinder. Further, simulations and theory found that the number of entanglements per chain decreases as the cylinder diameter decreases. This talk presents the local dynamics and polymer diffusion under cylindrical nanoconfinement using simulations and experiments. For the molecular dynamics simulations, an entangled polymer is confined by an amorphous cylindrical confinement. Local dynamics and local packing of monomers are affected by the cylindrical confinement and an anisotropic mean-squared displacement is observed with faster motion along the cylinder axes that increases with increasing confinement. Using elastic recoil detection experiments, polymer diffusion coefficients along cylindrical nanopores were measured for deuterated polystyrene diffusing into nanoporous membranes infiltrated with polystyrene. The tracer diffusion coefficient increased with decreasing pore size, although the increase is less pronounced than found in the simulations. Results will be discussed in terms of the reptation model.
Passively Damped Laminated Piezoelectric Shell Structures with Integrated Electric Networks
Saravanos, Dimitris A.
1999-01-01
Multi-field mechanics are presented for curvilinear piezoelectric laminates interfaced with distributed passive electric components. The equations of motion for laminated piezoelectric shell structures with embedded passive electric networks are directly formulated and solved using a finite element methodology. The modal damping and frequencies of the piezoelectric shell are calculated from the poles of the system. Experimental and numerical results are presented for the modal damping and frequency of composite beams with a resistively shunted piezoceramic patch. The modal damping and frequency of plates, cylindrical shells and cylindrical composite blades with piezoelectric-resistor layers are predicted. Both analytical and experimental studies illustrate a unique dependence of modal damping and frequencies on the shunting resistance and show the effect of structural shape and curvature on piezoelectric damping.
IODINE REMOVAL EFFICIENCY IN NON-SUBMERGED AND SUBMERGED SELF-PRIMING VENTURI SCRUBBER
Ali, Majid; CHANGQI, YAN; ZHONGNING, SUN; HAIFENG, GU; JUNLONG, WANG; MEHBOOB, KHURRAM
2013-01-01
The objective of this conducted research is to study the iodine removal efficiency in a self-priming venturi scrubber for submerged and non-submerged operating conditions experimentally and theoretically. The alkaline solution is used as an absorbent, which is prepared by dissolving sodium hydroxide (NaOH) and sodium thiosulphate (Na2S2O3) in water to remove the gaseous iodine (I2) from the gas. Iodine removal efficiency is examined at various gas flow rates and inlet concentrations of iodine...
An Analytical Solution for Cylindrical Concrete Tank on Deformable Soil
Directory of Open Access Journals (Sweden)
Shirish Vichare
2010-07-01
Full Text Available Cylindrical concrete tanks are commonly used in wastewater treatment plants. These are usually clarifier tanks. Design codes of practice provide methods to calculate design forces in the wall and raft of such tanks. These methods neglect self-weight of tank material and assume extreme, namely ‘fixed’ and ‘hinged’ conditions for the wall bottom. However, when founded on deformable soil, the actual condition at the wall bottom is neither fixed nor hinged. Further, the self-weight of the tank wall does affect the design forces. Thus, it is required to offer better insight of the combined effect of deformable soil and bottom raft stiffness on the design forces induced in such cylindrical concrete tanks. A systematic analytical method based on fundamental equations of shells is presented in this paper. Important observations on variation of design forces across the wall and the raft with different soil conditions are given. Set of commonly used tanks, are analysed using equations developed in the paper and are appended at the end.
Scour around a submerged cylinder and marine hydrokinetic (MHK) device in live-bed conditions
Beninati, Maria Laura; Volpe, Michael; Krane, Michael; Fontaine, Arnold
2013-11-01
Experiments are presented to explore how sediment scour around a single Marine Hydrokinetic (MHK) turbine varies with flow speed. Three Reynolds numbers, based on support structure diameter were used to induce live-bed scour conditions. Based on results from previous studies on submerged cylinders, differences in scour patterns between a single cylinder and MHK device can be determined. In the case of MHK energy, many devices are submerged in the flow. Thus, it is important to analyze the impact of both the support structure and the addition of the rotating blades. The experiments were performed in the small-scale testing platform in the hydraulic flume facility at Bucknell University. For each test case, bed form topology was measured after a three-hour time interval using a traversing two-dimensional bed profiler. During the experiment, scour depth measurements at the front face of the cylindrical support structure were taken to estimate the scour rate. Measurements of the bed form were taken across the width of the test section. Results show that the scour hole dimensions increase in the presence of the MHK device. These dimensions also increase with increasing Reynolds number.
Submergence tolerance in Hordeum marinum
DEFF Research Database (Denmark)
Pedersen, Ole; Malik, Al I.; Colmer, Timothy D.
2010-01-01
Floodwaters differ markedly in dissolved CO(2), yet the effects of CO(2) on submergence responses of terrestrial plants have rarely been examined. The influence of dissolved CO(2) on underwater photosynthesis and growth was evaluated for three accessions of the wetland plant Hordeum marinum Huds......) movement, would all contribute to submergence tolerance in H. marinum. The present study demonstrates that dissolved CO(2) levels can determine submergence tolerance of terrestrial plants. So, submergence experiments should be conducted with defined CO(2) concentrations and enrichment might be needed...
Calibration of submerged multi-sluice gates
Directory of Open Access Journals (Sweden)
Mohamed F. Sauida
2014-09-01
The main objective of this work is to study experimentally and verify empirically the different parameters affecting the discharge through submerged multiple sluice gates (i.e., the expansion ratios, gates operational management, etc.. Using multiple regression analysis of the experimental results, a general equation for discharge coefficient is developed. The results show, that the increase in the expansion ratio and the asymmetric operation of gates, give higher values for the discharge coefficient. The obtained predictions of the discharge coefficient using the developed equations are compared to the experimental data. The present developed equations showed good consistency and high accuracy.
Analysis, Design and Optimization of Non-Cylindrical Fuselage for Blended-Wing-Body (BWB) Vehicle
Mukhopadhyay, V.; Sobieszczanski-Sobieski, J.; Kosaka, I.; Quinn, G.; Charpentier, C.
2002-01-01
Initial results of an investigation towards finding an efficient non-cylindrical fuselage configuration for a conceptual blended-wing-body flight vehicle were presented. A simplified 2-D beam column analysis and optimization was performed first. Then a set of detailed finite element models of deep sandwich panel and ribbed shell construction concepts were analyzed and optimized. Generally these concepts with flat surfaces were found to be structurally inefficient to withstand internal pressure and resultant compressive loads simultaneously. Alternatively, a set of multi-bubble fuselage configuration concepts were developed for balancing internal cabin pressure load efficiently, through membrane stress in inner-stiffened shell and inter-cabin walls. An outer-ribbed shell was designed to prevent buckling due to external resultant compressive loads. Initial results from finite element analysis appear to be promising. These concepts should be developed further to exploit their inherent structurally efficiency.
Polotsky, A.; Charlaganov, M.; Xu, Y.P.; Leermakers, F.A.M.; Daoud, M.; Muller, A.H.E.; Dotera, T.; Borisov, O.V.
2008-01-01
We present theoretical arguments and experimental evidence for a longitudinal instability in core-shell cylindrical polymer brushes with a solvophobic inner (core) block and a solvophilic outer (shell) block in selective solvents. The two-gradient self-consistent field Scheutjens-Fleer (SCF-SF)
Cylindrical-shaped nanotube field effect transistor
Hussain, Muhammad Mustafa
2015-12-29
A cylindrical-shaped nanotube FET may be manufactured on silicon (Si) substrates as a ring etched into a gate stack and filled with semiconductor material. An inner gate electrode couples to a region of the gate stack inside the inner circumference of the ring. An outer gate electrode couples to a region of the gate stack outside the outer circumference of the ring. The multi-gate cylindrical-shaped nanotube FET operates in volume inversion for ring widths below 15 nanometers. The cylindrical-shaped nanotube FET demonstrates better short channel effect (SCE) mitigation and higher performance (I.sub.on/I.sub.off) than conventional transistor devices. The cylindrical-shaped nanotube FET may also be manufactured with higher yields and cheaper costs than conventional transistors.
Damage detection in submerged plates using ultrasonic guided waves
Indian Academy of Sciences (India)
Suitable ultrasonic guided wave modes with optimum scanning capabilities have been generated and identified in submerged plate system. Finally, the propagation of selected modes through submerged notched plates is investigated. Sensitivity of leaky waves to the notches has been studied. The methodology would help ...
Automating a submerged pump method for operating oil wells
Energy Technology Data Exchange (ETDEWEB)
Popa, I.
1984-01-01
The basic parameters of wells which operate in a mode of submerged operation are presented. The basic systems for measuring and testing the parameters of submerged operation are described. Worldwide experience in solving this particular problem is analyzed. Romanian (SRR) use of systems for automation, remote signaling and remote management is examined.
Impacts of climate change on submerged and emergent wetland plants
Frederick T. Short; Sarian Kosten; Pamela A. Morgan; Sparkle L Malone; Gregg E. Moore
2016-01-01
Submerged and emergent wetland plant communities are evaluated for their response to global climate change (GCC), focusing on seagrasses, submerged freshwater plants, tidal marsh plants, freshwater marsh plants and mangroves. Similarities and differences are assessed in plant community responses to temperature increase, CO2increase, greater UV-B exposure, sea...
Identification of a novel submergence response gene regulated by ...
African Journals Online (AJOL)
Tuoyo Aghomotsegin
2016-12-07
Dec 7, 2016 ... 3Engineering Research Center of Ecology and Agricultural Use of Wetland, Ministry of Education, Yangzte University,. Jingzhou 434025, P.R. .... intolerance to submergence) and M202(Sub1A) by qRT-. PCR. We identified a novel gene responsive to submergence, called RS1. The expression patterns of.
Identification of a novel submergence response gene regulated by ...
African Journals Online (AJOL)
Our results also show that RS1 is highly expressed under submergence, drought, and NaCl stresses, but not under cold or dehydration stress. Hormone ABA treatment induces, whereas GA treatment decreases, RS1 expression. The RS1 and Sub1A genes are co-regulated under submergence. Overexpression of RS1 in ...
Spherical shells buckling to the sound of music
Lee, Anna; Marthelot, Joel; Reis, Pedro
We study how the critical buckling load of spherical elastic shells can be modified by a fluctuating external pressure field. In our experiments, we employ thin elastomeric shells of nearly uniform thickness fabricated by the coating of a hemispherical mold with a polymer solution, which upon curing yields elastic structures. A shell is submerged in a water bath and loaded quasi-statically until buckling occurs by reducing its inner volume with a syringe pump. Simultaneously, a plunger connected to an electromagnetic shaker is placed above the shell and driven sinusoidally to create a fluctuating external pressure field that can excite dynamic vibration modes of the shell. These dynamic modes induce effective compressive stresses, in addition to those from the inner pressure loading, which can modify the critical conditions for the onset of buckling. We systematically quantify how the frequency and amplitude of the external driving affects the buckling strength of our shells. In specific regions of the parameter space, we find that pressure fluctuations can result in large reductions of the critical buckling pressure. This is analogous to the classic knock-down effect in shells due to intrinsic geometric imperfections, albeit now in a way that can be controlled externally.
Cylindrical Antenna Using Near Zero Index Metamaterial
2012-07-24
about their vertical axes could also be used. These include, but are not be limited to, dipole antennas and biconical antennas . [0022] The anomalous...COVERED 00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE Cylindrical Antenna Using Near Zero Index Metamaterial 5a. CONTRACT NUMBER 5b. GRANT...1 Attorney Docket No. 101380 CYLINDRICAL ANTENNA USING NEAR ZERO INDEX METAMATERIAL STATEMENT OF GOVERNMENT INTEREST [0001] The invention
Experimental and Numerical Research on Cylindrical Tubes under Outer Cylindrical Explosive Waves
Sui Yaguang; Zhang Dezhi; Tang Shiying; Chen Bo
2017-01-01
Cylindrical explosive loading has an important application in explosive working, researching on weapon damage, and explosive-driving load. This study uses experimental and numerical methods to study the response of long and thin tubes when subjected to cylindrical explosive loading. The flake-like charge and multipoint initiation technique were adopted to load cylindrical explosive waves. Experimental results showed that the method could produce uniform deformation in certain parts of the lon...
Energy Technology Data Exchange (ETDEWEB)
Choi, Myung Soo; Choi, Hee Jong [Chonnam National University, Yeosu (Korea, Republic of); Kondou, Takahiro [Kyushu University, Fukuoka (Japan)
2015-07-15
We developed a computational method for effectively conducting the free vibration analysis of axisymmetric shells with various shapes. This paper describes a computational algorithm for the free vibration analysis of axisymmetric shells using the Sylvester-transfer stiffness coefficient method (S-TSCM). From the free vibration analyses of three axisymmetric shells (joined conical-cylindrical shell, hermetic capsule and built-up shell), we verified the applicability of the S-TSCM. We then confirmed that the computational power of the S-TSCM is much better than both the finite element-transfer matrix method and finite element-transfer stiffness coefficient method, in terms of computational accuracy and time. In particular, when axisymmetric shells are modeled into a large number of conical shell elements, the S-TSCM is superior to both the bisection method using Sturm sequence property and Jacobi method, in terms of computational time and storage.
Laser-matter Interaction with Submerged Samples
Energy Technology Data Exchange (ETDEWEB)
Mariella, R; Rubenchik, A; Norton, M; Donohue, G; Roberts, K
2010-03-25
With the long-term goal in mind of investigating if one could possibly design a 'universal solid-sample comminution technique' for debris and rubble, we have studied pulsed-laser ablation of solid samples that were contained within a surrounding fluid. Using pulses with fluences between 2 J and 0.3 J, wavelengths of 351 and 527 nm, and samples of rock, concrete, and red brick, each submerged in water, we have observed conditions in which {micro}m-scale particles can be preferentially generated in a controlled manner, during the laser ablation process. Others have studied laser peening of metals, where their attention has been to the substrate. Our study uses non-metallic substrates and analyzes the particles that are ablated from the process. The immediate impact of our investigation is that laser-comminution portion of a new systems concept for chemical analysis has been verified as feasible.
Submerged arc welding of heavy plate
Wilson, R. A.
1972-01-01
The submerged arc process is particularly suitable for heavy plate welding because of its ability to combine very high deposit rates along with excellent quality. It does these things without the smoke and spatter often accompanying other processes. It is available today in several forms that are pointed to the fabricators of heavy sections with long, short or round about welds. Tandem arc full automatic equipment is particularly suitable for those long heavy welds where speed and deposit rate are of the first order. An attachment called long stick-out which makes use of the IR drop on long electrode extensions can be included on this equipment to increase deposition rates 50% or more.
Modeling tabular icebergs submerged in the ocean
Stern, A. A.; Adcroft, A.; Sergienko, O.; Marques, G.
2017-08-01
Large tabular icebergs calved from Antarctic ice shelves have long lifetimes (due to their large size), during which they drift across large distances, altering ambient ocean circulation, bottom-water formation, sea-ice formation, and biological primary productivity in the icebergs' vicinity. However, despite their importance, the current generation of ocean circulation models usually do not represent large tabular icebergs. In this study, we develop a novel framework to model large tabular icebergs submerged in the ocean. In this framework, tabular icebergs are represented by pressure-exerting Lagrangian elements that drift in the ocean. The elements are held together and interact with each other via bonds. A breaking of these bonds allows the model to emulate calving events (i.e., detachment of a tabular iceberg from an ice shelf) and tabular icebergs breaking up into smaller pieces. Idealized simulations of a calving tabular iceberg, its drift, and its breakup demonstrate capabilities of the developed framework.
Crassulacean acid metabolism in submerged aquatic plants
Keeley, Jon E.; Sybesme, C.
1984-01-01
CO2-fixation in the dark is known to occur in various organs of many plants. However, only in species possessing crassulacean acid metabolism (CAM) does dark CO2-fixation contribute substantially to the carbon economy of the plant. Until very recently CAM was known only from terrestrial species, largely drought adapted succulents. The discovery of CAM in the submerged aquatic fern ally Isoetes howellii (Isoetaceae)(Keeley 1981) adds a new dimension to our understanding of crassulacean acid metabolism. In this paper I will summarize 1) the evidence of CAM in Isoetes howellii, 2) the data on the distribution of CAM in aquatic species, and 3) the work to date on the functional significance of CAM in aquatic species.
Cross flow response of a cylindrical structure under local shear flow
Directory of Open Access Journals (Sweden)
Yoo-Chul Kim
2009-12-01
Full Text Available The VIV (Vortex-Induced Vibration analysis of a flexible cylindrical structure under locally strong shear flow is presented. The model is made of Teflon and has 9.5m length, 0.0127m diameter, and 0.001m wall thickness. 11 2-dimensional accelerometers are installed along the model. The experiment has been conducted at the ocean engineering basin in the University of Tokyo in which uniform current can be generated. The model is installed at about 30 degree of slope and submerged by almost overall length. Local shear flow is made by superposing uniform current and accelerated flow generated by an impeller. The results of frequency and modal analysis are presented.
Workshop on ROVs and deep submergence
The deep-submergence community has an opportunity on March 6 to participate in a unique teleconferencing demonstration of a state-of-the-art, remotely operated underwater research vehicle known as the Jason-Medea System. Jason-Medea has been developed over the past decade by scientists, engineers, and technicians at the Deep Submergence Laboratory at Woods Hole Oceanographic Institution. The U.S. Navy, the Office of the Chief of Naval Research, and the National Science Foundation are sponsoring the workshop to explore the roles that modern computational, communications, and robotics technologies can play in deep-sea oceanographic research.Through the cooperation of Electronic Data Systems, Inc., the Jason Foundation, and Turner Broadcasting System, Inc., 2-1/2 hours of air time will be available from 3:00 to 5:30 PM EST on March 6. Twenty-seven satellite downlink sites will link one operating research vessel and the land-based operation with workshop participants in the United States, Canada, the United Kingdom, and Bermuda. The research ship Laney Chouest will be in the midst of a 3-week educational/research program in the Sea of Cortez, between Baja California and mainland Mexico. This effort is focused on active hydrothermal vents driven by heat flow from the volcanically active East Pacific Rise, which underlies the sediment-covered Guaymas Basin. The project combines into a single-operation, newly-developed robotic systems, state-of-the-art mapping and sampling tools, fiber-optic data transmission from the seafloor, instantaneous satellite communication from ship to shore, and a sophisticated array of computational and telecommunications networks. During the workshop, land-based scientists will observe and participate directly with their seagoing colleagues as they conduct seafloor research.
Submerged membrane distillation for seawater desalination
Francis, Lijo
2014-08-11
A submerged membrane distillation (SMD) process for fresh water production from Red Sea water using commercially available hollow fiber membranes has been successfully employed and compared with the conventional direct contact membrane distillation (DCMD) process. The hollow fiber membranes have been characterized for its morphology using field effect scanning electron microscope. In SMD process, a bunch of hollow fiber membranes are glued together at both ends to get a simplified open membrane module assembly submerged into the coolant tank equipped with a mechanical stirrer. Hot feed stream is allowed to pass through the lumen side of the membrane using a feed pump. Continuous stirring at the coolant side will reduce the temperature and concentration polarization. During the conventional DCMD process, using feed-coolant streams with co-current and counter-current flows has been tested and the results are compared in this study. In SMD process, a water vapor flux of 10.2 kg m-2 h-1 is achieved when using a feed inlet temperature of 80°C and coolant temperature of 20°C. Under the same conditions, during conventional DCMD process, a water vapor flux of 11.6 and 10.1 kg m-2 h-1 were observed during counter-current and co-current flow streams, respectively. Results show that the water production in the SMD process is comparable with the conventional DCMD process, while the feed-coolant flow streams are in the co-current direction. During conventional DCMD operation, a 15% increase in the water production is observed when feed-coolant streams are in the counter-current direction compared to the co-current direction. © 2014 © 2014 Balaban Desalination Publications. All rights reserved.
Fleming, W.J.; Ailstock, M.S.; Momot, J.J.; Norman, C.M.; Gorsuch, Joseph W.; Lower, William R.; Wang, Wun-cheng; Lewis, M.A.
1991-01-01
The phytotoxicity of atrazine, paraquat, glyphosate, and alachlor to sago pondweed (Potamogeton pectinatus), a submerged aquatic macrophyte, was tested under three types of laboratory culture conditions. In each case, tests were conducted in static systems, the test period was four weeks, and herbicide exposure was chronic, resulting from a single addition of herbicide to the test vessels at the beginning of the test period. The three sets of test conditions employed were(1) axenic cultures in 125-mL flasks containing a nutrient media and sucrose; (2) a microcosm system employing 18.9-L buckets containing a sand, shell, and peat substrate; and (3) an algae-free system employing O.95-L jars containing reconstituted freshwater and a nutrient agar substrate. The primary variable measured was biomass production. Plants grew well in all three test systems, with biomass of untreated plants increasing by a factor of about 5 to 6.5 during the four-week test period. Biomass production in response to herbicide exposure differed significantly among culture systems, which demonstrates the need for a standardized testing protocol for evaluating the effects of toxics on submerged aquatic plants.
FASOR - A second generation shell of revolution code
Cohen, G. A.
1978-01-01
An integrated computer program entitled Field Analysis of Shells of Revolution (FASOR) currently under development for NASA is described. When completed, this code will treat prebuckling, buckling, initial postbuckling and vibrations under axisymmetric static loads as well as linear response and bifurcation under asymmetric static loads. Although these modes of response are treated by existing programs, FASOR extends the class of problems treated to include general anisotropy and transverse shear deformations of stiffened laminated shells. At the same time, a primary goal is to develop a program which is free of the usual problems of modeling, numerical convergence and ill-conditioning, laborious problem setup, limitations on problem size and interpretation of output. The field method is briefly described, the shell differential equations are cast in a suitable form for solution by this method and essential aspects of the input format are presented. Numerical results are given for both unstiffened and stiffened anisotropic cylindrical shells and compared with previously published analytical solutions.
Imperfection surveys on a 10-ft-diameter shell structure
Arbocz, J.; Williams, J. G.
1977-01-01
The results of an extensive imperfection survey on a 10-ft-diameter integrally stiffened cylindrical shell are presented. The shape of the measured initial imperfections is clearly influenced by details of the shell construction. The modal components of the measured imperfection surface as a function of the circumferential and of the axial wave numbers are calculated. The discrete axial power spectral density functions and the corresponding root-mean-square values of the imperfections are also determined for given circumferential wave numbers. Using the Fourier coefficients of the measured initial imperfections, buckling loads are calculated by solving the nonlinear Donnell-type imperfect shell equations iteratively. The calculated lowest buckling load compares favorably with the values usually recommended for similar shell structures.
Numerical simulation on a new cylindrical target for Z-pinch driven inertial confinement fusion
Chu, Y. Y.; Wang, Z.; Qi, J. M.; Wu, F. Y.; Li, Z. H.
2017-06-01
A new indirectly driven cylindrical target is proposed for Z-pinch inertial confinement fusion, and the target implosion dynamics is simulated with a combination of the mass-point model and the radiation hydrodynamic model. Driven by a current waveform with the peak value of 60 MA and 10-90% rising time of 180 ns, the shell kinetic energy of 5 MJ cm-1 can be obtained when the 60 mg cm-1 liner with initial radius 5 cm is imploded to radius of 5 mm. The simulated kinetic energy is loaded to compress the multi-layer cylindrical target, and 24.6 MJ fusion energy can be released according to the radiation hydrodynamic simulation. The power balance relationship is analyzed for the fusion fuel, and the fuel is ignited in the volume-ignition style. The target here can avoid the problem of coupling between the cylindrical Z-pinch and spherical fusion capsule, and can make use of dynamics hohlraum to weaken the influence of Z-pinch instability on the fuel compression. The implosion dynamics of the cylindrical fusion target is easy to diagnose from the axial direction, which makes it suitable to be investigated in future experiments.
A frameless, cylindrically shaped, multiwire proportional chamber using charge division readout
Fainberg, A; Linscott, I; Moneti, G
1977-01-01
PWCs have been constructed in the shape of cylindrical quandrants, placed them around the bicone in an experiment at the CERN ISR, and operated them in a charge division mode to obtain two dimensional position information. A pair of PWCs share a cylindrical styrofoam shell as the basic support member, and contain approximately 0.008 radiation lengths of material. The observed charge division resolution is delta x/L approximately 0.5% in reasonable agreement with an expected resolution of approximately 0.3% due primarily to digitization noise. Reduction of digitization noise is limited by available dynamic range of the electronics and the width of the pulse height distributions. A method is described, using X-rays from /sup 55 /Fe strip sources for calibrating the electronics, which is sufficiently accurate to match the observed resolution. (13 refs).
Magnetization processes in core/shell exchange-spring structures.
Energy Technology Data Exchange (ETDEWEB)
Jiang, J. S.
2015-03-27
The magnetization reversal processes in cylindrical and spherical soft core/hard shell exchange-spring structures are investigated via the analytical nucleation theory, and are verified with numerical micromagnetic simulations. At small core sizes, the nucleation of magnetic reversal proceeds via the modified bulging mode, where the transverse component of the magnetization is only semi-coherent in direction and the nucleation field contains a contribution from self-demagnetization. For large core sizes, the modified curling mode, where the magnetization configuration is vortex-like, is favored at nucleation. The preference for the modified curling mode is beneficial in that the fluxclosure allows cylindrical and spherical core/shell exchange-spring elements to be densely packed into bulk permanent magnets without affecting the nucleation field, thereby offering the potential for high energy product.
Electronic Quantum Confinement in Cylindrical Potential Well
Baltenkov, A S
2016-01-01
The effects of quantum confinement on the momentum distribution of electrons confined within a cylindrical potential well have been analyzed. The motivation is to understand specific features of the momentum distribution of electrons when the electron behavior is completely controlled by the parameters of a non-isotropic potential cavity. It is shown that studying the solutions of the wave equation for an electron confined in a cylindrical potential well offers the possibility to analyze the confinement behavior of an electron executing one- or two-dimensional motion in the three-dimensional space within the framework of the same mathematical model. Some low-lying electronic states with different symmetries have been considered and the corresponding wave functions have been calculated; the behavior of their nodes and their peak positions with respect to the parameters of the cylindrical well has been analyzed. Additionally, the momentum distributions of electrons in these states have been calculated. The limi...
Saravanos, Dimitris A.
1996-01-01
Mechanics for the analysis of laminated composite shells with piezoelectric actuators and sensors are presented. A new mixed-field laminate theory for piezoelectric shells is formulated in curvilinear coordinates which combines single-layer assumptions for the displacements and a layerwise representation for the electric potential. The resultant coupled governing equations for curvilinear piezoelectric laminates are described. Structural mechanics are subsequently developed and an 8-node finite-element is formulated for the static and dynamic analysis of adaptive composite structures of general laminations containing piezoelectric layers. Evaluations of the method and comparisons with reported results are presented for laminated piezoelectric-composite plates, a closed cylindrical shell with a continuous piezoceramic layer and a laminated composite semi-circular cantilever shell with discrete cylindrical piezoelectric actuators and/or sensors.
Micromagnetic simulations of cylindrical magnetic nanowires
Ivanov, Yurii P.
2015-05-27
This chapter reviews micromagnetic simulations of cylindrical magnetic nanowires and their ordered arrays. It starts with a description of the theoretical background of micromagnetism. The chapter discusses main magnetization reversal modes, domain wall types, and state diagrams in cylindrical nanowires of different types and sizes. The results of the hysteresis process in individual nanowires and nanowire arrays also are presented. Modeling results are compared with experimental ones. The chapter also discusses future trends in nanowire applications in relation to simulations, such as current-driven dynamics, spintronics, and spincaloritronics. The main micromagnetic programs are presented and discussed, together with the corresponding links.
Boosted cylindrical magnetized Kaluza-Klein wormhole
Hashemi, S. Sedigheh; Riazi, Nematollah
2018-02-01
In this work, we consider a vacuum solution of Kaluza-Klein theory with cylindrical symmetry. We investigate the physical properties of the solution as viewed in four dimensional spacetime, which turns out to be a stationary, cylindrical wormhole supported by a scalar field and a magnetic field oriented along the wormhole. We then apply a boost to the five dimensional solution along the extra dimension, and perform the Kaluza-Klein reduction. As a result, we show that the new solution is still a wormhole with a radial electric field and a magnetic field stretched along the wormhole throat.
POLARON IN CYLINDRICAL AND SPHERICAL QUANTUM DOTS
Directory of Open Access Journals (Sweden)
L.C.Fai
2004-01-01
Full Text Available Polaron states in cylindrical and spherical quantum dots with parabolic confinement potentials are investigated applying the Feynman variational principle. It is observed that for both kinds of quantum dots the polaron energy and mass increase with the increase of Frohlich electron-phonon coupling constant and confinement frequency. In the case of a spherical quantum dot, the polaron energy for the strong coupling is found to be greater than that of a cylindrical quantum dot. The energy and mass are found to be monotonically increasing functions of the coupling constant and the confinement frequency.
Shell ontogeny in radiolarians
Digital Repository Service at National Institute of Oceanography (India)
Anderson, O.R.; Gupta, S.M.
The ontogeny of the shells in modern and ancient radiolarian species, Acrosphaera cyrtodon were observed by scanning and transmission electron microscopy. The shells of A. cyrtodon were obtained from core samples collected from the Central Indian...
Durability performance of submerged concrete structures - phase 2.
2015-09-01
This project determined that severe corrosion of steel can occur in the submerged : portions of reinforced concrete structures in marine environments. Field studies of decommissioned : pilings from Florida bridges revealed multiple instances of stron...
Submerged Aquatic Vegetation of Bogue Sound, North Carolina 1992 Geodatabase
National Oceanic and Atmospheric Administration, Department of Commerce — During 1992, 1:20,000 scale aerial photography for Bogue Sound, North Carolina was collected as part of an effort to map submerged aquatic vegetation (SAV) in...
Submerged Aquatic Vegetation of Bogue Sound, North Carolina 1992 Substrate
National Oceanic and Atmospheric Administration, Department of Commerce — During 1992, 1:20,000 scale aerial photography for Bogue Sound, North Carolina was collected as part of an effort to map submerged aquatic vegetation (SAV) in...
Marine algal flora of submerged Angria Bank (Arabian Sea)
Digital Repository Service at National Institute of Oceanography (India)
Untawale, A.G.; Reddy, C.R.K.; Ambiye, V.
Submerged Angria Bank was surveyed for the deep water marine algal flora. About 57 species were reported from this bank for the first time. Rhodophyta dominated (30 species) followed by Chlorophyta (18 species) and Phaeophyta (9 species). A few...
Submerged Aquatic Vegetation of Bogue Sound, North Carolina 1992 Biotic
National Oceanic and Atmospheric Administration, Department of Commerce — During 1992, 1:20,000 scale aerial photography for Bogue Sound, North Carolina was collected as part of an effort to map submerged aquatic vegetation (SAV) in...
Submerged Aquatic Vegetation of Bogue Sound, North Carolina 1992 Geoform
National Oceanic and Atmospheric Administration, Department of Commerce — During 1992, 1:20,000 scale aerial photography for Bogue Sound, North Carolina was collected as part of an effort to map submerged aquatic vegetation (SAV) in...
Supporting Calculations For Submerged Bed Scrubber Condensate Disposal Preconceptual Study
Energy Technology Data Exchange (ETDEWEB)
Pajunen, A. J.; Tedeschi, A. R.
2012-09-18
This document provides supporting calculations for the preparation of the Submerged Bed Scrubber Condensate Disposal Preconceptual Study report The supporting calculations include equipment sizing, Hazard Category determination, and LAW Melter Decontamination Factor Adjustments.
Impeded Carbohydrate Metabolism in Rice Plants under Submergence Stress
Directory of Open Access Journals (Sweden)
Malay Kumar ADAK
2011-06-01
Full Text Available The detrimental effects of submergence on physiological performances of some rice varieties with special references to carbohydrate metabolisms and their allied enzymes during post-flowering stages have been documented and clarified in the present investigation. It was found that photosynthetic rate and concomitant translocation of sugars into the panicles were both related to the yield. The detrimental effects of the complete submergence were recorded in generation of sucrose, starch, sucrose phosphate synthase and phosphorylase activity in the developing panicles of the plants as compared to those under normal or control (i.e. non-submerged condition. The accumulation of starch was significantly lower in plants under submergence and that was correlated with ADP-glucose pyrophosphorylase activity. Photosynthetic rate was most affected under submergence in varying days of post-flowering and was also related to the down regulation of Ribulose bisphosphate carboxylase activity. However, under normal or control condition, there recorded a steady maintenance of photosynthetic rate at the post-flowering stages and significantly higher values of Ribulose bisphosphate carboxylase activity. Still, photosynthetic rate of the plants under both control and submerged conditions had hardly any significant correlation with sugar accumulation and other enzymes of carbohydrate metabolism like invertase with grain yield. Finally, plants under submergence suffered significant loss of yield by poor grain filling which was related to impeded carbohydrate metabolism in the tissues. It is evident that loss of yield under submergence is attributed both by lower sink size or sink capacity (number of panicles, in this case as well as subdued carbohydrate metabolism in plants and its subsequent partitioning into the grains.
Incipient motion of sediment in presence of submerged flexible vegetation
Wang, Hao; Tang, Hong-Wu; Zhao, Han-Qing; Xuan-yu ZHAO; Lü, Sheng-qi
2015-01-01
The presence of submerged vegetation on river beds can change the water flow structure and alter the state of sediment motion. In this study, the incipient motion of sediment in the presence of submerged flexible vegetation in open channels was investigated in a laboratory experiment. The vegetation was simulated with flexible rubber cylinders arranged in parallel arrays. The effect of the vegetation density, water depth, and sediment grain size on the incipient motion was investigated. The e...
Impact of the Excitation Source and Plasmonic Material on Cylindrical Active Coated Nano-Particles
DEFF Research Database (Denmark)
Arslanagic, Samel; Liu, Yan; Malureanu, Radu
2011-01-01
Electromagnetic properties of cylindrical active coated nano-particles comprised of a silica nano-cylinder core layered with a plasmonic concentric nano-shell are investigated for potential nano-sensor applications. Particular attention is devoted to the near-field properties of these particles......, as well as to their far-field radiation characteristics, in the presence of an electric or a magnetic line source. A constant frequency canonical gain model is used to account for the gain introduced in the dielectric part of the nano-particle, whereas three different plasmonic materials (silver, gold...
1966-10-01
This report describes the testing performed with reef shell, clam shell and a combination of reef and clam shell used as coarse aggregate to determine if a low modulus concrete could be developed for use as a base material as an alternate to the pres...
Heat transfer model for quenching by submerging
Energy Technology Data Exchange (ETDEWEB)
Passarella, D N; Varas, F [Departamento de Matematica Aplicada II, E.T.S. de Ing. de Telecomunicacion, Universidad de Vigo, Campus Marcosende, 36310 Vigo (Spain); MartIn, E B, E-mail: diego@dma.uvigo.es, E-mail: fvaras@uvigo.es, E-mail: emortega@uvigo.es [Area de Mecanica de Fluidos, E.T.S. de Ing. Industriales, Universidad de Vigo, Campus Marcosende, 36310 Vigo (Spain)
2011-05-01
In quenching by submerging the workpiece is cooled due to vaporization, convective flow and interaction of both mechanisms. The dynamics of these phenomena is very complex and the corresponding heat fluxes are strongly dependent on local flow variables such as velocity of fluid and vapor fraction. This local dependence may produce very different cooling rates along the piece, responsible for inappropriate metallurgical transformations, variability of material properties and residual stresses. In order to obtain an accurate description of cooling during quenching, a mathematical model of heat transfer is presented here. The model is based on the drift-flux mixture-model for multiphase flows, including an equation of conservation of energy for the liquid phase and specific boundary conditions that account for evaporation and presence of vapor phase on the surface of the piece. The model was implemented on Comsol Multiphysics software. Generation of appropriate initial and boundary conditions, as well as numerical resolution details, is briefly discussed. To test the model, a simple flow condition was analyzed. The effect of vapor fraction on heat transfer is assessed. The presence of the typical vapor blanket and its collapse can be recovered by the model, and its effect on the cooling rates on different parts of the piece is analyzed. Comparisons between numerical results and data from literature are made.
Method of initial functions for thick transversely isotropic shells
Energy Technology Data Exchange (ETDEWEB)
Faraji, S. (Lowell Univ., MA (USA). Dept. of Civil Engineering); Archer, R.R. (Massachusetts Univ., Amherst (USA). Dept. of Civil Engineering)
1989-10-10
In the present work for circular cylindrical shells, three-dimensional elasticity equations are solved by assuming Taylor series expansions, in the radial direction, for the stresses and displacements. Depending upon the number of terms retained in the expansion, different order shell theories are derived. Classical theories (referred to as eighth-order), the shear deformation-transverse normal stress theories (referred to as tenth-order), and higher order theories (referred to as twelfth-order) are derived. In each case, by carrying out the symbolic algebra using the digital computer, partial differential equations are derived. The procedure was carried out in detail for the case of a circular cyclindrical shell with no loading on the interior surface and a given pressure distribution on the exterior surface. Then, numerical comparisons are made between the current theories and various shell theories, as well as the exact (three-dimensional) theory. Thus, using this method with its associated computer programs, one can realize a spectrum of approximate shell theories ranging from the classical thin shell, through all current thick shell theories, and approaching the three-dimensional elastic theories. (orig.).
Stein, M.
1985-01-01
Nonlinear strain displacement relations for three-dimensional elasticity are determined in orthogonal curvilinear coordinates. To develop a two-dimensional theory, the displacements are expressed by trigonometric series representation through-the-thickness. The nonlinear strain-displacement relations are expanded into series which contain all first and second degree terms. In the series for the displacements only the first few terms are retained. Insertion of the expansions into the three-dimensional virtual work expression leads to nonlinear equations of equilibrium for laminated and thick plates and shells that include the effects of transverse shearing. Equations of equilibrium and buckling equations are derived for flat plates and cylindrical shells. The shell equations reduce to conventional transverse shearing shell equations when the effects of the trigonometric terms are omitted and to classical shell equations when the trigonometric terms are omitted and the shell is assumed to be thin.
Antibubbles and fine cylindrical sheets of air
Beilharz, D.
2015-08-14
Drops impacting at low velocities onto a pool surface can stretch out thin hemispherical sheets of air between the drop and the pool. These air sheets can remain intact until they reach submicron thicknesses, at which point they rupture to form a myriad of microbubbles. By impacting a higher-viscosity drop onto a lower-viscosity pool, we have explored new geometries of such air films. In this way we are able to maintain stable air layers which can wrap around the entire drop to form repeatable antibubbles, i.e. spherical air layers bounded by inner and outer liquid masses. Furthermore, for the most viscous drops they enter the pool trailing a viscous thread reaching all the way to the pinch-off nozzle. The air sheet can also wrap around this thread and remain stable over an extended period of time to form a cylindrical air sheet. We study the parameter regime where these structures appear and their subsequent breakup. The stability of these thin cylindrical air sheets is inconsistent with inviscid stability theory, suggesting stabilization by lubrication forces within the submicron air layer. We use interferometry to measure the air-layer thickness versus depth along the cylindrical air sheet and around the drop. The air film is thickest above the equator of the drop, but thinner below the drop and up along the air cylinder. Based on microbubble volumes, the thickness of the cylindrical air layer becomes less than 100 nm before it ruptures.
Metastable magnetic domain walls in cylindrical nanowires
Energy Technology Data Exchange (ETDEWEB)
Ferguson, C.A.; MacLaren, D.A.; McVitie, S., E-mail: Stephen.McVitie@glasgow.ac.uk
2015-05-01
The stability of the asymmetric domain wall (ATDW) in soft magnetic cylindrical nanowires and nanotubes is investigated using micromagnetic simulations. Our calculated phase diagram shows that for cylindrical permalloy nanowires, the transverse domain wall (TDW) is the ground state for radii below 20 nm whilst the Bloch point wall (BPW) is favoured in thicker wires. The ATDW stabilises only as a metastable state but with energy close to that of the BPW. Characterisation of the DW spin structures reveals that the ATDW has a vortex-like surface spin state, in contrast to the divergent surface spins of the TDW. This results in lowering of surface charge above the critical radius. For both cylindrical nanotubes and nanowires we find that ATDWs only appear to exist as metastable static states and are particularly suppressed in nanotubes due to an increase in magnetostatic energy. - Highlights: • We simulate the micromagnetic structures of domain walls in cylindrical nanowires. • A phase diagram identifies ground and metastable states. • Asymmetric transverse walls are metastable in nanowires but suppressed in tubes. • Unrolling surface magnetisation aids visualisation of asymmetry and chirality. • We predict experimental discrimination based on magnetic charge distribution.
Low Frequency Sloshing Analysis of Cylindrical Containers with Flat and Conical Baffles
Directory of Open Access Journals (Sweden)
Gnitko V.
2017-12-01
Full Text Available This paper presents an analysis of low-frequency liquid vibrations in rigid partially filled containers with baffles. The liquid is supposed to be an ideal and incompressible one and its flow is irrotational. A compound shell of revolution is considered as the container model. For evaluating the velocity potential the system of singular boundary integral equations has been obtained. The single-domain and multi-domain reduced boundary element methods have been used for its numerical solution. The numerical simulation is performed to validate the proposed method and to estimate the sloshing frequencies and modes of fluid-filled cylindrical shells with baffles in the forms of circular plates and truncated cones. Both axisymmetric and non-axisymmetric modes of liquid vibrations in baffled and un-baffled tanks have been considered. The proposed method makes it possible to determine a suitable place with a proper height for installing baffles in tanks by using the numerical experiment.
Experimental and Numerical Research on Cylindrical Tubes under Outer Cylindrical Explosive Waves
Directory of Open Access Journals (Sweden)
Sui Yaguang
2017-01-01
Full Text Available Cylindrical explosive loading has an important application in explosive working, researching on weapon damage, and explosive-driving load. This study uses experimental and numerical methods to study the response of long and thin tubes when subjected to cylindrical explosive loading. The flake-like charge and multipoint initiation technique were adopted to load cylindrical explosive waves. Experimental results showed that the method could produce uniform deformation in certain parts of the long tube, but partial spall injuries occurred after the explosion. The macroscopic and microscopic deformation of tubes were analyzed. Numerical simulations were conducted to investigate the detailed response of the tube subjected to a cylindrical explosive wave. The results indicate that the collision of explosive waves brought inconsistencies in pressure and velocity. The pressure and velocity in the collision region were significantly higher than those of other parts, which caused the collision region to be easily damaged.
Fast liner proposal. [Magnetic implosions of cylindrical liners
Energy Technology Data Exchange (ETDEWEB)
Sherwood, A.R.; Freeman, B.L.; Gerwin, R.A.; Jarboe, T.R.; Krakowski, R.A.; Malone, R.C.; Marshall, J.; Miller, R.L.; Suydam, B.
1977-08-01
This is a proposal to study, both theoretically and experimentally, the possibility of making a fusion reactor by magnetically imploding a cylindrical metallic shell on a prepared plasma. The approach is characterized by the following features: (1) the nonrotating liner would be driven by an axial current, (2) the plasma would also carry an axial current that provides an azimuthal magnetic field for thermal insulation in both the radial and longitudinal directions, (3) solid end plugs would be utilized to prevent axial loss of particles, and (4) liner speeds would be in the 10/sup 6/ cm/s range. The preliminary calculations indicate (1) that the energetics are favorable (energy inputs of about 10 MJ might produce a machine in the break-even regime), (2) that radiation and heat losses could be made tolerable, (3) that alpha-particle heating could be made very effective, and (4) that Taylor instabilities in a fast liner might be harmless because of the large viscosities at high pressures. A preliminary conceptual design of the sort of fusion reactor that might result from such an approach is discussed, as are some of the relevant reactor scaling arguments.
Submerged cultivation of medicinal mushrooms: bioprocesses and products (review).
Elisashvili, Vladimir
2012-01-01
Medicinal mushrooms belonging to higher Basidiomycetes are an immensely rich yet largely untapped resource of useful, easily accessible, natural compounds with various biological activities that may promote human well-being. The medicinal properties are found in various cellular components and secondary metabolites (polysaccharides, proteins and their complexes, phenolic compounds, polyketides, triterpenoids, steroids, alkaloids, nucleotides, etc.), which have been isolated and identified from the fruiting bodies, culture mycelium, and culture broth of mushrooms. Some of these compounds have cholesterol-lowering, anti-diabetic, antioxidant, antitumor, immunomodulating, antimicrobial, and antiviral activities ready for industrial trials and further commercialization, while others are in various stages of development. Recently, the submerged cultivation of medicinal mushrooms has received a great deal of attention as a promising and reproducible alternative for the efficient production of mushroom mycelium and metabolites. Submerged cultivation of mushrooms has significant industrial potential, but its success on a commercial scale depends on increasing product yields and development of novel production systems that address the problems associated with this technique of mushroom cultivation. In spite of many researchers' efforts for the production of bioactive metabolites by mushrooms, the physiological and engineering aspects of submerged cultures are still far from being thoroughly studied. The vast majority of studies have focused on polysaccharide and ganoderic acid production in submerged cultivation of medicinal mushrooms, and very little has been written so far on the antioxidant and hemagglutinating activity of submerged mushroom cultures. The purpose of this review is to provide an update of the present state of the art and future prospects of submerged cultivation of medicinal mushrooms to produce mycelium and bioactive metabolites, and to make a
Robotic Hand with Flexible Fingers for Grasping Cylindrical Objects
柴田, 瑞穂
2015-01-01
In this manuscript, a robotic hand for grasping a cylindrical object is proposed. This robotic hand has flexible fingers that can hold a cylindrical object during moving. We introduce a grasping strategy for a cylindrical object in terms of state transition graph. In this strategy the robotic hand picks up the cylindrical object utilizing a suction device before the hand grasp the object. We also design the flexible fingers; then, we investigate the validity of this robotic hand via several e...
Spectral-domain analysis of single and coupled cylindrical striplines
Deshpande, Manohar D.; Reddy, C. Jagadeswara
1987-01-01
A spectral-domain technique for finding the characteristic impedances of a single cylindrical stripline and a coupled pair of cylindrical striplines is presented. Assuming a charge distribution on the strip, the variational expression for the line capacitance for single cylindrical stripline is derived. Good agreement with published results is obtained. The cylindrical coupled strip and microstrip lines are also analyzed and a comparison with their planar counterparts is made.
Origin of Spontaneous Core-Shell AIGaAs Nanowires Grown by Molecular Beam Epitaxy
DEFF Research Database (Denmark)
Dubrovskii, V. G.; Shtrom, I. V.; Reznik, R. R.
2016-01-01
Based on the high-angle annular dark-field scanning transmission electron microscopy and energy dispersive X-ray spectroscopy studies, we unravel the origin of spontaneous core shell AlGaAs nanowires grown by gold-assisted molecular beam epitaxy. Our AlGaAs nanowires have a cylindrical core...
Cylindrical continuous martingales and stochastic integration in infinite dimensions
Veraar, M.C.; Yaroslavtsev, I.S.
2016-01-01
In this paper we define a new type of quadratic variation for cylindrical continuous local martingales on an infinite dimensional spaces. It is shown that a large class of cylindrical continuous local martingales has such a quadratic variation. For this new class of cylindrical continuous local
Fluctuating shells under pressure
Paulose, Jayson; Vliegenthart, Gerard A.; Gompper, Gerhard; Nelson, David R.
2012-01-01
Thermal fluctuations strongly modify the large length-scale elastic behavior of cross-linked membranes, giving rise to scale-dependent elastic moduli. Whereas thermal effects in flat membranes are well understood, many natural and artificial microstructures are modeled as thin elastic shells. Shells are distinguished from flat membranes by their nonzero curvature, which provides a size-dependent coupling between the in-plane stretching modes and the out-of-plane undulations. In addition, a shell can support a pressure difference between its interior and its exterior. Little is known about the effect of thermal fluctuations on the elastic properties of shells. Here, we study the statistical mechanics of shape fluctuations in a pressurized spherical shell, using perturbation theory and Monte Carlo computer simulations, explicitly including the effects of curvature and an inward pressure. We predict novel properties of fluctuating thin shells under point indentations and pressure-induced deformations. The contribution due to thermal fluctuations increases with increasing ratio of shell radius to thickness and dominates the response when the product of this ratio and the thermal energy becomes large compared with the bending rigidity of the shell. Thermal effects are enhanced when a large uniform inward pressure acts on the shell and diverge as this pressure approaches the classical buckling transition of the shell. Our results are relevant for the elasticity and osmotic collapse of microcapsules. PMID:23150558
Buckling optimisation of sandwich cylindrical panels
Abouhamzeh, M.; Sadighi, M.
2016-06-01
In this paper, the buckling load optimisation is performed on sandwich cylindrical panels. A finite element program is developed in MATLAB to solve the governing differential equations of the global buckling of the structure. In order to find the optimal solution, the genetic algorithm Toolbox in MATLAB is implemented. Verifications are made for both the buckling finite element code and also the results from the genetic algorithm by comparisons to the results available in literature. Sandwich cylindrical panels are optimised for the buckling strength with isotropic or orthotropic cores with different boundary conditions. Results are presented in terms of stacking sequence of fibers in the face sheets and core to face sheet thickness ratio.
Skyrmion oscillations in chiral cylindrical nanowires
Charilaou, Michalis; Loeffler, Joerg
The occurrence of skyrmions on surfaces due to the competition of symmetric and antisymmetric interactions is a fascinating phenomenon with a promising potential for new technologies. The spatial confinement of spin textures in nanostructures, such as thin films, and the breaking of symmetry by an external or internal field enable the formation of skyrmions and skyrmion lattices. In cylindrical nanowires, the spatial confinement and the symmetry-breaking field are provided by the solid itself due to magnetostatics, i.e., shape anisotropy. Based on high-resolution micromagnetic simulations we will show that in cylindrical nanowires of FeGe non-trivial skyrmionic spin textures occur, which resemble a skyrmion chain. These break the translational symmetry along the wire via an oscillation of the topological charge. We will also discuss how external fields can manipulate the skyrmion-chain state and how magnetization switching occurs via the formation of Bloch points.
Determination of Coil Inductances Cylindrical Iron Nucleus
Directory of Open Access Journals (Sweden)
Azeddine Mazouz
2014-03-01
Full Text Available The paper describes the investigation and development of a structure and performance characteristics of a coil iron nucleus cylindrical (C.I.N.C. The coil iron nucleus cylindrical is a nonlinear electro radio in which the moving of the nucleus in a sense or in other causes change in inductance and can reach extreme values at the superposition of nucleus and coil centers. The variation of the inductance and the degree of freedom of movement of the nucleus can lead to a device with electromechanical conversion The aim of this paper is the determination and visualization of self inductance and mutual of the (C.I.N.C based on geometric dimensions and the displacement of the nucleus.
Nanolaminate Membranes as Cylindrical Telescope Reflectors
Dooley, Jennifer; Dragovan, Mark; Hickey, Gregory; Lih, Shyh-Shiu Lih
2010-01-01
A document discusses a proposal to use axially stretched metal nanolaminate membranes as lightweight parabolic cylindrical reflectors in the Dual Anamorphic Reflector Telescope (DART) - a planned spaceborne telescope in which the cylindrical reflectors would be arranged to obtain a point focus. The discussion brings together a combination of concepts reported separately in several prior NASA Tech Briefs articles, the most relevant being "Nanolaminate Mirrors With Integral Figure-Control Actuators" NPO -30221, Vol. 26, No. 5 (May 2002), page 90; and "Reflectors Made From Membranes Stretched Between Beams" NPO -30571, Vol. 33, No. 10 (October 2009), page 11a. The engineering issues receiving the greatest emphasis in the instant document are (1) the change in curvature associated with the Poisson contraction of a stretched nanolaminate reflector membrane and (2) the feasibility of using patches of poly(vinylidene fluoride) on the rear membrane surface as piezoelectric actuators to correct the surface figure for the effect of Poisson contraction and other shape errors.
Magnetic guns with cylindrical permanent magnets
Czech Academy of Sciences Publication Activity Database
Vokoun, David; Beleggia, M.; Heller, Luděk
2012-01-01
Roč. 324, č. 9 (2012), s. 1715-1719 ISSN 0304-8853 R&D Projects: GA ČR(CZ) GAP107/11/0391; GA AV ČR IAA100100920 Institutional research plan: CEZ:AV0Z10100520 Keywords : permanent magnet * cylindrical magnet * Earnshaw's theorem * magnet ic gun * magnet ostatic interaction Subject RIV: BM - Solid Matter Physics ; Magnet ism Impact factor: 1.826, year: 2012 http://www.sciencedirect.com/science/article/pii/S0304885311008997
Marching Cubes in Cylindrical and Spherical Coordinates
Goldsmith, J.; Jacobson, A. S.
1996-01-01
Isosurface extraction is a common analysis and visualization technique for three-dimensional scalar data. Marching Cubes is the most commonly-used algorithm for finding polygonal representations of isosurfaces in such data. We extend Marching Cubes to produce geometry for data sets that lie in spherical and cylindrical coordinate systems as well as show the steps for derivation of transformations for other coordinate systems.
Machining Thin-Walled Cylindrical Parts
Cimbak, Joe; Spagnolo, Jim; Kraus, Dan
1988-01-01
Cylindrical walls only few thousandths of inch thick machined accurately and without tears or punctures with aid of beryllium copper mandrel. Chilled so it contracts, then inserted in cylinder. As comes to room temperature, mandrel expands and fits snugly inside cylinder. Will not allow part to slide and provides solid backup to prevent deflection when part machined by grinding wheel. When machining finished, cylinder-and-mandrel assembly inserted in dry ice, mandrel contracts and removed from part.
Cylindric-like algebras and algebraic logic
Ferenczi, Miklós; Németi, István
2013-01-01
Algebraic logic is a subject in the interface between logic, algebra and geometry, it has strong connections with category theory and combinatorics. Tarski’s quest for finding structure in logic leads to cylindric-like algebras as studied in this book, they are among the main players in Tarskian algebraic logic. Cylindric algebra theory can be viewed in many ways: as an algebraic form of definability theory, as a study of higher-dimensional relations, as an enrichment of Boolean Algebra theory, or, as logic in geometric form (“cylindric” in the name refers to geometric aspects). Cylindric-like algebras have a wide range of applications, in, e.g., natural language theory, data-base theory, stochastics, and even in relativity theory. The present volume, consisting of 18 survey papers, intends to give an overview of the main achievements and new research directions in the past 30 years, since the publication of the Henkin-Monk-Tarski monographs. It is dedicated to the memory of Leon Henkin.
Flow-Induced Vibration of Circular Cylindrical Structures
Energy Technology Data Exchange (ETDEWEB)
Chen, Shoei-Sheng [Argonne National Lab. (ANL), Argonne, IL (United States). Components Technology Division
1985-06-01
of heat exchanger tube banks are typical examples. Recently, flow-induced vibration has been studied extensively for several reasons. First, with the use of high-strength materials, structures become more slender and more susceptible to vibration. Second, the development of advanced nuclear power reactors requires high-velocity fluid flowing through components, which can cause detrimental vibrations. Third, the dynamic interaction of structure and fluid is one of the most fascinating problems in engineering mechanics. The increasing study is evidenced by many conferences directed to this subject and numerous publications, including reviews and books. In a broad sense, flow-induced vibration encompasses all topics on the dynamic responses of structures submerged in fluid, containing fluid, or subjected to external flow. In this report, discussions focus on circular cylindrical structures with emphasis on nuclear reactor system components.
Robustness of Hierarchical Laminated Shell Element Based on Equivalent Single-Layer Theory
Directory of Open Access Journals (Sweden)
Jae S. Ahn
2015-01-01
Full Text Available This paper deals with the hierarchical laminated shell elements with nonsensitivity to adverse conditions for linear static analysis of cylindrical problems. Displacement approximation of the elements is established by high-order shape functions using the integrals of Legendre polynomials to ensure C0 continuity at the interface between adjacent elements. For exact linear mapping of cylindrical shell problems, cylindrical coordinate is adopted. To find global response of laminated composite shells, equivalent single-layer theory is also considered. Thus, the proposed elements are formulated by the dimensional reduction from three-dimensional solid to two-dimensional plane which allows the first-order shear deformation and considers anisotropy due to fiber orientation. The sensitivity tests are implemented to show robustness of the present elements with respect to severe element distortions, very high aspect ratios of elements, and very large radius-to-thickness ratios of shells. In addition, this element has investigated whether material conditions such as isotropic and orthotropic properties may affect the accuracy as the element distortion ratio is increased. The robustness of present element has been compared with that of several shell elements available in ANSYS program.
Locke, Anna M; Barding, Gregory A; Sathnur, Sumukh; Larive, Cynthia K; Bailey-Serres, Julia
2017-11-02
The rice (Oryza sativa L.) ethylene-responsive transcription factor gene SUB1A-1 confers tolerance to prolonged, complete submergence by limiting underwater elongation growth. Upon desubmergence, SUB1A-1 genotypes rapidly recover photosynthetic function and recommence development towards flowering. The underpinnings of the transition from stress amelioration to the return to homeostasis are not well known. Here, transcriptomic and metabolomic analyses were conducted to identify mechanisms by which SUB1A improves physiological function over the 24 hr following a sublethal submergence event. Evaluation of near-isogenic genotypes after submergence and over a day of reaeration demonstrated that SUB1A transiently constrains the remodelling of cellular activities associated with growth. SUB1A influenced the abundance of ca. 1,400 transcripts and had a continued impact on metabolite content, particularly free amino acids, glucose, and sucrose, throughout the recovery period. SUB1A promoted recovery of metabolic homeostasis but had limited influence on mRNAs associated with growth processes and photosynthesis. The involvement of low energy sensing during submergence and recovery was supported by dynamics in trehalose-6-phosphate and mRNAs encoding key enzymes and signalling proteins, which were modulated by SUB1A. This study provides new evidence of convergent signalling pathways critical to the rapidly reversible management of carbon and nitrogen metabolism in submergence resilient rice. © 2017 John Wiley & Sons Ltd.
Altenbach, Holm
2011-01-01
In this volume, scientists and researchers from industry discuss the new trends in simulation and computing shell-like structures. The focus is put on the following problems: new theories (based on two-dimensional field equations but describing non-classical effects), new constitutive equations (for materials like sandwiches, foams, etc. and which can be combined with the two-dimensional shell equations), complex structures (folded, branching and/or self intersecting shell structures, etc.) and shell-like structures on different scales (for example: nano-tubes) or very thin structures (similar
Computer-Controlled Cylindrical Polishing Process for Large X-Ray Mirror Mandrels
Khan, Gufran S.; Gubarev, Mikhail; Speegle, Chet; Ramsey, Brian
2010-01-01
We are developing high-energy grazing incidence shell optics for hard-x-ray telescopes. The resolution of a mirror shells depends on the quality of cylindrical mandrel from which they are being replicated. Mid-spatial-frequency axial figure error is a dominant contributor in the error budget of the mandrel. This paper presents our efforts to develop a deterministic cylindrical polishing process in order to keep the mid-spatial-frequency axial figure errors to a minimum. Simulation software is developed to model the residual surface figure errors of a mandrel due to the polishing process parameters and the tools used, as well as to compute the optical performance of the optics. The study carried out using the developed software was focused on establishing a relationship between the polishing process parameters and the mid-spatial-frequency error generation. The process parameters modeled are the speeds of the lap and the mandrel, the tool s influence function, the contour path (dwell) of the tools, their shape and the distribution of the tools on the polishing lap. Using the inputs from the mathematical model, a mandrel having conical approximated Wolter-1 geometry, has been polished on a newly developed computer-controlled cylindrical polishing machine. The preliminary results of a series of polishing experiments demonstrate a qualitative agreement with the developed model. We report our first experimental results and discuss plans for further improvements in the polishing process. The ability to simulate the polishing process is critical to optimize the polishing process, improve the mandrel quality and significantly reduce the cost of mandrel production
Peculiarities of thermal dissociation of oxides during submerged arc welding
Directory of Open Access Journals (Sweden)
Leonid Zhdanov
2013-12-01
Full Text Available A method of settlement of the process of thermal dissociation of oxides in reaction zone during the submerged arc welding and welding deposition is presented. Combined non-linear equations for definition of gas-vapour mixture composition were developed. They describe the dissociation of MeO, MeO2 and Me2O3 types of oxides. Calculations of the processes of oxide dissociation were performed for the oxides that are commonly included into welding fluxes. Their results and analysis are presented. The method proposed appeared to be adequate and applicable for analysis of processes during submerged arc operation that run in the gas phase.
EAARL-B Submerged TopographyÂSaint Croix, U.S. Virgin Islands, 2014
U.S. Geological Survey, Department of the Interior — A submerged topography digital elevation model (DEM) mosaic for a portion of the submerged environs of Saint Croix, U.S. Virgin Islands, was produced from remotely...
EAARL-B Submerged Topography--Saint Thomas, U.S. Virgin Islands, 2014
U.S. Geological Survey, Department of the Interior — A submerged topography Digital Elevation Model (DEM) mosaic for a portion of the submerged environs of Saint Thomas, U.S. Virgin Islands, was produced from remotely...
Long-term allelopathic control of phytoplankton by the submerged macrophyte Elodea nuttallii
Vanderstukken, M.; Declerck, S.A.J.; Decaestecker, E.; Muylaert, K.
2014-01-01
Keywords: allelochemicals; chemical ecology; competition; nutrient limitation; shallow lakes Summary 1.It is well known that submerged macrophytes can suppress phytoplankton blooms in lakes and thus promote water quality and biodiversity. One of the possible mechanisms through which submerged
Invasive Crayfish Threaten the Development of Submerged Macrophytes in Lake Restoration
Wal, van der J.E.M.; Dorenbosch, M.; Immers, A.K.; Vidal Forteza, C.; Geurts Van Kessel, J.M.M.; Peeters, E.T.H.M.; Koese, B.; Bakker, E.S.
2013-01-01
Submerged macrophytes enhance water transparency and aquatic biodiversity in shallow water ecosystems. Therefore, the return of submerged macrophytes is the target of many lake restoration projects. However, at present, north-western European aquatic ecosystems are increasingly invaded by omnivorous
Invasive crayfish threaten the development of submerged macrophytes in lake restoration
Van der Wal, J.E.M.; Dorenbosch, M.; Immers, A.; Vidal Forteza, C.; Geurts, J.J.M.; Peeters, E.T.H.M.; Koese, B.; Bakker, E.S.
2013-01-01
Submerged macrophytes enhance water transparency and aquatic biodiversity in shallow water ecosystems. Therefore, the return of submerged macrophytes is the target of many lake restoration projects. However, at present, north-western European aquatic ecosystems are increasingly invaded by omnivorous
Through-flow of water in leaves of a submerged plant is influenced by the apical opening
DEFF Research Database (Denmark)
Pedersen, Ole; Jørgensen, Lise Bolt; Sand-Jensen, Kaj
1997-01-01
Submerged plant, apical opening, hydathode, Sparganium, hydraulic architecture, leaf specific conductivity......Submerged plant, apical opening, hydathode, Sparganium, hydraulic architecture, leaf specific conductivity...
Stability analysis of whirling composite shells partially filled with two liquid phases
Energy Technology Data Exchange (ETDEWEB)
Sahebnasagh, Mohammad [Department of Mechanical Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Nikkhah-Bahrami, Mansour; Firouz-Abadi, Roohollah [Department of Aerospace Engineering, Sharif University, Tehran (Iran, Islamic Republic of)
2017-05-15
In this paper, the stability of whirling composite cylindrical shells partially filled with two liquid phases is studied. Using the first-order shear shell theory, the structural dynamics of the shell is modeled and based on the Navier-Stokes equations for ideal liquid, a 2D model is developed for liquid motion at each section of the cylinder. In steady state condition, liquids are supposed to locate according to mass density. In this study, the thick shells are investigated. Using boundary conditions between liquids, the model of coupled fluid-structure system is obtained. This coupled fluid-structure model is employed to determine the critical speed of the system. The effects of the main variables on the stability of the shell are studied and the results are investigated.
Directory of Open Access Journals (Sweden)
A. V. Derepa
2017-01-01
Full Text Available System in the form of a circular cylindrical piezoceramic transducer near a flat acoustic screen was analyzed. The aim of the work was to solve the problem of receiving plane sound waves by «cylindrical piezoceramic transducer – flat acoustically soft screen» system.Considered system was characterized by a violation of the radial symmetry of the radiation load of the transducer while maintaining the radial symmetry of the electric load. At the same time, the energy perceived by the system under consideration is distributed between all modes of oscillation of the transducer, while the conversion of mechanical energy into electric is realized only at zero mole of oscillations.Special attention was paid to the method of coupled fields in multiply connected domains using the imaging method. The design model of the «transducer–creen» system was formulated taking into account the interaction of acoustic, mechanical and electric fields in the process of energy conversion, the interaction of a cylindrical transducer with a flat screen and the interaction of a converter with elastic media outside and inside it. The physical fields of the system under consideration were determined by following solutions: the wave equation; equations of motion of thin piezoceramic cylindrical shells in displacements; equations of stimulated electrostatics for piezoceramics for given boundary conditions, conditions for coupling fields at interfaces and electrical conditions.A general conclusion was made concerning solving of an infinite system of linear algebraic equations with respect to the unknown coefficients of the expansion of the fields. As an example of the application of the obtained relations, a calculation was made and an analysis of the dependences of the electric fields of the system under consideration for various parameters of its construction on the direction of arrival on the plane wave system was conducted.
African Journals Online (AJOL)
Valley. Although fossil specimens of this subspecies have been used in palaeoclimatic reconstruction, there have been no previous reports of living examples. Here We describe the local habitat, climate and some aspects of ecology and isotopic variation within the snail shell. If isotope data can be obtained for fossil shells, ...
Newham, Cameron
2005-01-01
This refreshed edition serves as the most valuable guide yet to the bash shell. It's full of practical examples of shell commands and programs guaranteed to make everyday use of Linux that much easier. Includes information on key bindings, command line editing and processing, integrated programming features, signal handling, and much more!
Hydrogen mitigation in submerged arc welding
Klimowicz, Steven
With the role of hydrogen in weld metal well understood in its relation to cold cracking, there has been a push to produce welds with lower and lower diffusible hydrogen contents. The push for lower diffusible hydrogen contents has placed pressure on consumables manufactures to create consumables that can achieve the requirements for lower diffusible hydrogen content. Currently EM12K flux is produced so that it can achieve below 4 ml of diffusible hydrogen for every 100g of weld metal deposited (ml/100g) for submerged arc welding (SAW). The recent trend for industry is to preferentially achieve diffusible hydrogen contents below 3 ml/100g. Making it necessary to find a way to modify the flux to achieve a lower diffusible hydrogen content for the welds it produces. To achieve this goal a two phase plan was developed. The first phase was to characterize the entire welding system for hydrogen. Since the goal of the project is hydrogen mitigation, any amount of hydrogen that could be reduced is helpful and therefore must first be discovered. Sources of hydrogen may be found by analyzing the welding wire and base metal, as well as breaking the flux down into its components and production steps. The wire was analyzed for total hydrogen content as was the base metal. The flux and its components were analyzed using differential thermal analysis-simultaneous thermal analysis (DTA-STA) and later vacuum degassing for moisture content. The analysis of the wire showed that the copper coating on the wire was the largest contributor of hydrogen. There was lubricant present on the wire surface as well, but it did not contribute as much as the copper coating. It was found that a simple low temperature baking of the wire was enough to remove the lubricant and coating moisture. The base metal was found to have a similar total hydrogen content to that of the wire. The breakdown of the flux and production process for moisture content analysis revealed that the production process
Motion parallax in immersive cylindrical display systems
Filliard, N.; Reymond, G.; Kemeny, A.; Berthoz, A.
2012-03-01
Motion parallax is a crucial visual cue produced by translations of the observer for the perception of depth and selfmotion. Therefore, tracking the observer viewpoint has become inevitable in immersive virtual (VR) reality systems (cylindrical screens, CAVE, head mounted displays) used e.g. in automotive industry (style reviews, architecture design, ergonomics studies) or in scientific studies of visual perception. The perception of a stable and rigid world requires that this visual cue be coherent with other extra-retinal (e.g. vestibular, kinesthetic) cues signaling ego-motion. Although world stability is never questioned in real world, rendering head coupled viewpoint in VR can lead to the perception of an illusory perception of unstable environments, unless a non-unity scale factor is applied on recorded head movements. Besides, cylindrical screens are usually used with static observers due to image distortions when rendering image for viewpoints different from a sweet spot. We developed a technique to compensate in real-time these non-linear visual distortions, in an industrial VR setup, based on a cylindrical screen projection system. Additionally, to evaluate the amount of discrepancies tolerated without perceptual distortions between visual and extraretinal cues, a "motion parallax gain" between the velocity of the observer's head and that of the virtual camera was introduced in this system. The influence of this artificial gain was measured on the gait stability of free-standing participants. Results indicate that, below unity, gains significantly alter postural control. Conversely, the influence of higher gains remains limited, suggesting a certain tolerance of observers to these conditions. Parallax gain amplification is therefore proposed as a possible solution to provide a wider exploration of space to users of immersive virtual reality systems.
Experimental investigation of cylindrical detonation wave
Dudin, S. V.; Sosikov, V. A.; Torunov, S. I.
2016-11-01
One of the methods of experimental investigation of cylindrical detonation wave formed by the multipoint initiation method is presented in this work. The experimental setup was specially developed for this purpose. Two types of “Nanogate” high-speed cameras were used in the experiments. The phenomenological descriptions of initiation process, dynamic of formation of detonation wave and gas dynamic flow of detonation products are presented. This method in combination with the other modern methods will allow carrying out more profound investigations of such problems.
Retaining Walls Made of Precast Cylindrical Valuts
Directory of Open Access Journals (Sweden)
N. Ungureanu
2005-01-01
Full Text Available Retaining walls are large category of engineering structures of multiple uses, having an essential safety ensuring role. The structural systems are varied because the situations and requirements derived from both site conditions and other criteria are varied. The paper enlarges upon retaining walls systems that use an outstanding amount of precast units and multiple cylindrical vault type structural systems supported by abutments [1], [2]. The paper proposes extending the structural system to retaining walls and develops certain specific issues. Some considerations regarding structural design are made.
Pembuatan Knowledge Management pada External Cylindrical Grinding
Directory of Open Access Journals (Sweden)
Ikhwan Arief
2016-04-01
The design began by analyzing the external cylindrical grinding systems and translate them into Unified Modelling Language (UML which was followed by the design of database and computer software, and test the software. The application software is web-based and can be accessed by multiple users. The application will help the operator in determining parameters with given option of parameter recommendation. The system gives recommendations based on the tacit knowledge that has been gathered into explicit knowledge. The output of the application is a list of selected parameters and report cases. Report data in the case will be used to set up the machine.
Proposed gas generation assembly would recover deeply submerged objects
Sprague, C. W.
1968-01-01
Gas generation system, used for recovery of submerged objects, generates hydrogen gas by the reaction of sodium with sea water. The assembly consists of flooded flotation tanks cabled together, equipped with relief valves to equalize pressure as the array ascends and hydrostatic pressure diminishes, and carrying remotely activated welding units.
Implementation of Submerged Arc Welding Training. Final Report.
Bowick, Earl; Todd, John
A unit on submerged arc welding (SAW) was developed and integrated into the welding program at Seattle Central Community College (Washington) during the period December 1983 through May 1984. During this time, 10 major users of SAW in the area were contacted and mailed questionnaires. Follow up consisted of telephone calls and personal contact as…
Benthic Bacterial Diversity in Submerged Sinkhole Ecosystems▿ †
Nold, Stephen C.; Pangborn, Joseph B.; Zajack, Heidi A.; Kendall, Scott T.; Rediske, Richard R.; Biddanda, Bopaiah A.
2010-01-01
Physicochemical characterization, automated ribosomal intergenic spacer analysis (ARISA) community profiling, and 16S rRNA gene sequencing approaches were used to study bacterial communities inhabiting submerged Lake Huron sinkholes inundated with hypoxic, sulfate-rich groundwater. Photosynthetic cyanobacterial mats on the sediment surface were dominated by Phormidium autumnale, while deeper, organically rich sediments contained diverse and active bacterial communities. PMID:19880643
Effects of submerged and anaerobic fermentations on cassava flour ...
African Journals Online (AJOL)
Oke Oluwatoyin Victoria
2015-03-18
Mar 18, 2015 ... Cassava tubers for processing into cassava flour, Lafun a Nigerian locally fermented product was subjected to two different types of fermentations: submerged and anaerobic fermentation for 72 h. Physicochemical changes that occurred during fermentation and their influence on the functional, rheological ...
Reactive oxygen species mediate growth and death in submerged plants
Directory of Open Access Journals (Sweden)
Bianka eSteffens
2013-06-01
Full Text Available Aquatic and semi-aquatic plants are well adapted to survive partial or complete submergence which is commonly accompanied by oxygen deprivation. The gaseous hormone ethylene controls a number of adaptive responses to submergence including adventitious root growth and aerenchyma formation. Reactive oxygen species (ROS act as signaling intermediates in ethylene-controlled submergence adaptation and possibly also independent of ethylene. ROS levels are controlled by synthesis, enzymatic metabolism and nonenzymatic scavenging. While the actors are by and large known, we still have to learn about altered ROS at the subcellular level and how they are brought about, and the signaling cascades that trigger a specific response. This review briefly summarizes our knowledge on the contribution of ROS to submergence adaptation and describes spectrophotometrical, histochemical and live cell imaging detection methods that have been used to study changes in ROS abundance. Electron paramagnetic resonance (EPR spectroscopy is introduced as a method that allows identification and quantification of specific ROS in cell compartments. The use of advanced technologies such as EPR spectroscopy will be necessary to untangle the intricate and partially interwoven signaling networks of ethylene and ROS.
Surface Intermediate Zone of Submerged Turbulent Buoyant Jet in Current
DEFF Research Database (Denmark)
Chen, H. B.; Larsen, Torben
1995-01-01
This paper deals with the intermediate zone between the jet and plume stages of a submerged buoyant discharge from sea outfall in current. The stability criteria, plume width and height after the intermediate zone and the dilution within the intermediate region have been studied theoretically and...
Effects of prolonged elevated water salinity on submerged ...
African Journals Online (AJOL)
environmental change, global warming. * To whom all correspondence should be addressed. e-mail: ian.russell@sanparks.org. Received 9 March 2017; accepted in revised form 10 October 2017. INTRODUCTION. Estuarine submerged macrophyte communities can be highly variable at both spatial and temporal scales, ...
Protein enrichment of cassava peel by submerged fermentation ...
African Journals Online (AJOL)
PRECIOUS
2010-01-11
Jan 11, 2010 ... Key words: Cassava peel, Trichoderma viride, enzyme, submerged fermentation, protein, amino acids. INTRODUCTION. Protein-energy malnutrition remains a major public health problem in many developing countries and there is the need to increase daily intake of protein, especially animal protein, using ...
Relationships between the biomass of waterfowl and submerged ...
African Journals Online (AJOL)
The Wilderness Lakes system, comprising three estuarine lakes (Eilandvlei, Langvlei and Rondevlei), supports a diverse waterbird community, which includes 12 duck species and the abundant Red-knobbed Coot Fulica cristata. Biannual counts of waterfowl (ducks and Red-knobbed Coot) and assessments of submerged ...
Protein enrichment of cassava peel by submerged fermentation with ...
African Journals Online (AJOL)
Protein enrichment of cassava peel by submerged fermentation with Trichoderma viride (ATCC 36316). OO Ezekiel, OC Aworh, HP Blaschek, TC Ezeji. Abstract. Cassava (Manihot esculenta Crantz) peel is one of the solid wastes produced as a consequence of cassava processing. It is low in protein but contains a large ...
Nitrification in a submerged attached growth bioreactor using Luffa ...
African Journals Online (AJOL)
A laboratory-scale submerged attached growth bioreactor using Luffa cylindrica as support material for the immobilization of nitrifying bacteria was applied for polishing the effluent of an UASB reactor treating domestic wastewater under the tropical conditions of northeast Brazil, in the City of Campina Grande (7o 13' 11” ...
Effects of submerged vegetation on water clarity across climates
Kosten, S.; Lacerot, G.; Jeppesen, E.; Motta Marques, D.M.L.; Nes, van E.H.; Mazzeo, N.; Scheffer, M.
2009-01-01
A positive feedback between submerged vegetation and water clarity forms the backbone of the alternative state theory in shallow lakes. The water clearing effect of aquatic vegetation may be caused by different physical, chemical, and biological mechanisms and has been studied mainly in temperate
Optical alignment of a cylindrical object
Song, Chaolong; Nguyen, Nam-Trung; Krishna Asundi, Anand
2009-03-01
This paper reports the use of theory of geometrical optics to analyze how an optical field interacts with a cylindrical object. Of great interest is the mechanism with which a laser beam with a special profile manipulates a particle which has a similar shape as the beam profile. The present paper investigates the interaction between a cylinder-shape fiber and a laser beam with a line-shape profile. Based on the Fresnel equation, a numerical model was formulated to describe the optical torque generated by a projected line-shape optical image. The drag force was also considered in the model to accurately describe the fiber's movement in a liquid. A differential equation is established to describe this damped movement of the cylinder. Parametric analysis was carried out to investigate the influence of the beam power and the liquid viscosity as well as the density, the length, and the diameter of the cylindrical object. The movement of a carbon fiber was measured with a CCD camera. The observed experimental results agree well with the theoretical results.
Cylindrical Optic Figuring and Dwell Time Optimization
Waluschka, Eugene
2000-01-01
Grazing incidence x-ray telescopes consist of surfaces which are nearly cylindrical in shape. The abrasive figuring of these surfaces is accomplished by moving a grinding tool along a helical path on this almost cylindrical surface. The measurement of the surface is, however, performed along "axial" scan lines which intercept this helical path. This approach to figuring and measuring permits a relatively simple scheme to be implemented for the determination of the optimal dwell times of the figuring tool. These optimal dwell times are determined by a deconvolution which approaches the problem in a linear programming context and uses the Simplex Method. The approach maximizes the amount of material removed at any point subject to inequality constraints. The effect of using these ''optimum" dwell times is to significantly improve the tools effectiveness at removing the higher spatial frequencies while staying (strictly) within the bounds and constraints imposed by the hardware. In addition, the ringing at the edges of the optic, frequently present in deconvolution problems, is completely eliminated.
de-Shalit, Amos; Massey, H S W
1963-01-01
Nuclear Shell Theory is a comprehensive textbook dealing with modern methods of the nuclear shell model. This book deals with the mathematical theory of a system of Fermions in a central field. It is divided into three parts. Part I discusses the single particle shell model. The second part focuses on the tensor algebra, two-particle systems. The last part covers three or more particle systems. Chapters on wave functions in a central field, tensor fields, and the m-Scheme are also presented. Physicists, graduate students, and teachers of nuclear physics will find the book invaluable.
Validation of Lower-Bound Estimates for Compression-Loaded Cylindrical Shells
Haynie, Waddy T.; Hilburger, Mark W.; Bogge, Massimiliano; Kriegesmann, Benedikt
2012-01-01
The traditional approach used in the design of stability critical thin-walled circular cylin- ders, is to reduce unconservative buckling load predictions with an empirical knockdown factor. An alternative analysis-based approach to determine a lower bound buckling load for cylinders under axial compression is to use a lateral perturbation load to create an initial imperfection and determine the buckling load while that load is applied. This paper describes a preliminary e ort to develop a test capability to verify this approach. Results from tests of three aluminum alloy cylinders are described and compared to nite element predictions.
Nemeth, Michael P.; Schultz, Marc R.
2012-01-01
A detailed exact solution is presented for laminated-composite circular cylinders with general wall construction and that undergo axisymmetric deformations. The overall solution is formulated in a general, systematic way and is based on the solution of a single fourth-order, nonhomogeneous ordinary differential equation with constant coefficients in which the radial displacement is the dependent variable. Moreover, the effects of general anisotropy are included and positive-definiteness of the strain energy is used to define uniquely the form of the basis functions spanning the solution space of the ordinary differential equation. Loading conditions are considered that include axisymmetric edge loads, surface tractions, and temperature fields. Likewise, all possible axisymmetric boundary conditions are considered. Results are presented for five examples that demonstrate a wide range of behavior for specially orthotropic and fully anisotropic cylinders.
Structural Performance of Fiber-Placed, Variable-Stiffness Composite Conical and Cylindrical Shells
Blom, A.W.
2010-01-01
The use of fiber-reinforced composites in aerospace structures has increased dramatically over the past decades. The high specific strength and stiffness, the tailorability, and the possibilities to integrate parts and reduce the number of fasteners give composites an advantage over metals.
DEFF Research Database (Denmark)
Arslanagic, Samel; Ziolkowski, Richard W.; Breinbjerg, Olav
2007-01-01
An antenna configuration that consists of an arbitrarily located electric line source that radiates in the presence of concentric metamaterial cylinders is examined. With the emphasis on the so-called quadrupolar structure, it is shown that such electrically small configurations may offer...... significant enhancements of the radiated power. Furthermore, the possibility of controlling the pattern by properly locating the electric line source with respect to the structure, thereby offering a means of obtaining electrically small metamaterial-based directive antennas, is also demonstrated....
Directory of Open Access Journals (Sweden)
Kalmykov Oleg
2017-01-01
Full Text Available The analysis of strain-stress state of new type of architectural and construction system ‘Monofant’ was examined. The analysis of the advanced graphic, computing software packages was carried out. The possibility of joint applying these packages to the problem of sustainable conjunction study of a rational combination of the geometric parameters of the design-built system “Monofant” was analyzed. From the constructive point of view, the search for the structural element shape that provides a minimum material consumption under desired conditions is of some interest. The approach based on the energy criterion of rationalization was adopted to solve this problem. Fundamentally, new opportunities in the field of building structures optimization are offered with introduction of visual programming complexes adopted for designers (Grasshopper, Dynamo. Applying the described approach to the problem of rationalizing of the constructive system “Monofant” offers the opportunity of constructing, calculating, analyzing and rationalizing of construction that has complex external and internal geometry. An illustration of a possible approach is given in a specific numerical example.
Dynamic Stability of Structures: Application to Frames, Cylindrical Shells and Other Systems.
1982-02-01
N4RS YOE) 882 COP~/ U - KO.,; K,1(3 K,hA o6.35)88 ~ 887 sad COMMON/lIE Wa PT /J PS , 1NX XPX C 8OUNCA Y*C.NJ:TIQrS d: eZ .6T,6Z ai 69 1 C LSx1 FOR SA...No. 4, pp. 701-706, December 1977. 191 ’ 7- 16. Simitses, G. J., Kounadis, A. N., and Gir , J., "Nonlinear suci:!ing Analysis of Imperfection Sensitive
Boedeltje, G; ter Heerdt, GNJ; Bakker, JP
Seed bank studies focused on submerged aquatic plants are generally performed under submerged conditions, using the seedling-emergence method. However, if a study targets at both submerged species and helophytes, submerged conditions are generally not suitable. We tested the emergence of seedlings
Sutley, Jane
2009-01-01
"Shells and Patterns" was a project the author felt would easily put smiles on the faces of her fifth-graders, and teach them about unity and the use of watercolor pencils as well. It was thrilling to see the excitement in her students as they made their line drawings of shells come to life. For the most part, they quickly got the hang of…
Study of Cylindrical Honeycomb Solar Collector
Directory of Open Access Journals (Sweden)
Atish Mozumder
2014-01-01
Full Text Available We present the results of our investigation on cylindrical honeycomb solar collector. The honeycomb has been fabricated with transparent cellulose triacetate polymer sheets. Insulation characteristics of the honeycomb were studied by varying the separation between the honeycomb and the absorber plate. The optimal value of the separation was found to be 3.3 mm for which the heat transfer coefficient is 3.06 W m−2 K−1. This supports result of previous similar experiments. Further we test the honeycomb through a field experiment conducted in Delhi (28.6°N, 77°E and found that when the incident angle of the solar radiation is within 20° then the performance of the system with the honeycomb is better than the one without the honeycomb.
Plasmonic oligomers in cylindrical vector light beams
Directory of Open Access Journals (Sweden)
Mario Hentschel
2013-01-01
Full Text Available We investigate the excitation as well as propagation of magnetic modes in plasmonic nanostructures. Such structures are particularly suited for excitation with cylindrical vector beams. We study magneto-inductive coupling between adjacent nanostructures. We utilize high-resolution lithographic techniques for the preparation of complex nanostructures consisting of gold as well as aluminium. These structures are subsequently characterized by linear optical spectroscopy. The well characterized and designed structures are afterwards studied in depth by exciting them with radial and azimuthally polarized light and simultaneously measuring their plasmonic near-field behavior. Additionally, we attempt to model and simulate our results, a project which has, to the best of our knowledge, not been attempted so far.
MIRW properties of cylindrical holes array nanostructure
Wen, Chunchao; Fu, Yuegang; Dong, Tingting; Zhou, Jianhong; Guo, Xudong
2017-03-01
To improve mediate infrared wavelength (MIRW) light energy transferring efficiency, the optical properties of antireflection micro/nanostructure with cylindrical holes periodic array on incident angle, wavelength, polarized angle and azimuth orientation was researched based on finite time-domain difference (FDTD) method. Results shows that the antireflection characteristics can be promised in wider spectral range and lager incident angles. Reflectivity function also presents different features as polarization and azimuth angles changed. These structure parameters were optimized to be period of 1 µm, duty cycle of 0.85 and erosion height of 0.5 µm. Samples of the structure were fabricated by electron beam exposure and reaction ion etch technology on silicon substrate. Finally, the diverse shape effect of bionic moth-eye was explored to give respective ideal parameters suitable for MIRW.
Unbalanced Cylindrical Magnetron for Accelerating Cavities Coating
Rosaz, Guillaume; Calatroni, Sergio; Sublet, Alban; Tobarelli, Mauro
2016-01-01
We report in this paper the design and qualification of a cylindrical unbalanced magnetron source. The dedicated magnetic assemblies were simulated using a finite element model. A hall-effect magnetic probe was then used to characterize those assemblies and compared to the theoretical magnet profiles. These show a good agreement between the expected and actual values. the qualification of the different magnetic assemblies was then performed by measuring the ion flux density reaching the surface of the sample to be coated using a commercial retarding field energy analyzer. The strongest unbalanced configuration shows an increase from 0.016A.cm^-2 to 0.074A.cm^-2 of the ion flux density reaching the sample surface compared to the standard balanced configuration for a pressure 5.10^-3 mbar and a plasma source power of 300W.
Confocal unrolled areal measurements of cylindrical surfaces
Matilla, A.; Bermudez, C.; Mariné, J.; Martínez, D.; Cadevall, C.; Artigas, R.
2017-06-01
Confocal microscopes are widely used for areal measurements thanks to its good height resolution and the capability to measure high local slopes. For the measurement of large areas while keeping few nm of system noise, it is needed to use high numerical aperture objectives, move the sample in the XY plane and stitch several fields together to cover the required surface. On cylindrical surfaces a rotational stage is used to measure fields along the round surface and stitch them in order to obtain a complete 3D measurement. The required amount of fields depends on the microscope's magnification, as well as on the cylinder diameter. However, for small diameters, if the local shape reaches slopes not suitable for the objective under use, the active field of the camera has to be reduced, leading to an increase of the required number of fields to be measured and stitched. In this paper we show a new approach for areal measurements of cylindrical surfaces that uses a rotational stage in combination with a slit projection confocal arrangement and a highspeed camera. An unrolled confocal image of the cylinder surface is built by rotating the sample and calculating the confocal intensity in the centre of the slit using a gradient algorithm. A set of 360º confocal images can be obtained at different heights of the sample relative to the sensor and used to calculate an unrolled areal measure of the cylinder. This method has several advantages over the conventional one such as no stitching required, or reduced measurement time. In addition, the result shows less residual flatness error since the surface lies flat in the measurement direction in comparison to field measures where the highest slope regions will show field distortion and non-constant sampling. We have also studied the influence on the areal measurements of wobble and run-out introduced by the clamping mechanism and the rotational axis.
Concentration profiles in drying cylindrical filaments
Czaputa, Klaus; Brenn, Günter; Meile, Walter
2008-12-01
We analyze theoretically the drying of cylindrical filaments. For modelling the mass transfer on the gas side of the liquid-gas interface of the shrinking circular cylindrical filament, we apply the model of Abramzon and Sirignano, which was originally developed for spherical geometry. As a consequence of mass transfer at constant Sherwood number, we obtain a d2-law for the shrinkage of the cylinder as in the case of the spherical geometry, which expresses that the cross-sectional area of the cylinder shrinks at a constant rate with time. For this situation, the diffusion equation for the liquid phase mixture components becomes separable upon transformation into similarity coordinates and is solved analytically to obtain the concentration profiles inside the filament as functions of time. The dependency of the profiles on the radial coordinate is determined by a series of Kummer’s functions. Applying this result, we study the evolution of the concentration profiles in the liquid phase with time as dependent on a parameter given as the ratio of rate of shrinkage of the cross-sectional area of the cylinder to liquid-phase diffusion coefficient, which was identified as relevant for the shape of the concentration profiles formed in the liquid during the drying process. As an example, we present computed results for the constant evaporation rate regime in the dry-spinning process of a polyvinyl-alcohol (PVA)-water system. Comparison of our analytical results with full numerical solutions of the diffusion equation from the literature, achieved with concentration-dependent diffusion coefficient, reveals very good agreement.
Concentration profiles in drying cylindrical filaments
Energy Technology Data Exchange (ETDEWEB)
Czaputa, Klaus; Brenn, Guenter; Meile, Walter [Graz University of Technology, Institute of Fluid Mechanics and Heat Transfer, Graz (Austria)
2008-12-15
We analyze theoretically the drying of cylindrical filaments. For modelling the mass transfer on the gas side of the liquid-gas interface of the shrinking circular cylindrical filament, we apply the model of Abramzon and Sirignano, which was originally developed for spherical geometry. As a consequence of mass transfer at constant Sherwood number, we obtain a d{sup 2}-law for the shrinkage of the cylinder as in the case of the spherical geometry, which expresses that the cross-sectional area of the cylinder shrinks at a constant rate with time. For this situation, the diffusion equation for the liquid phase mixture components becomes separable upon transformation into similarity coordinates and is solved analytically to obtain the concentration profiles inside the filament as functions of time. The dependency of the profiles on the radial coordinate is determined by a series of Kummer's functions. Applying this result, we study the evolution of the concentration profiles in the liquid phase with time as dependent on a parameter given as the ratio of rate of shrinkage of the cross-sectional area of the cylinder to liquid-phase diffusion coefficient, which was identified as relevant for the shape of the concentration profiles formed in the liquid during the drying process. As an example, we present computed results for the constant evaporation rate regime in the dry-spinning process of a polyvinyl-alcohol (PVA)-water system. Comparison of our analytical results with full numerical solutions of the diffusion equation from the literature, achieved with concentration-dependent diffusion coefficient, reveals very good agreement. (orig.)
Starnes, James H., Jr.; Hilburger, Mark W.
2003-01-01
The results of an experimental and analytical study of the effects of initial imperfections on the buckling response of unstiffened thin-walled compression-loaded graphite-epoxy cylindrical shells are presented. The analytical results include the effects of traditional and nontraditional initial imperfections and uncertainties in the values of selected shell parameters on the buckling loads of the shells. The nonlinear structural analysis results correlate very well with the experimental results. The high-fidelity nonlinear analysis procedure used to generate the analytical results can also be used to form the basis of a new shell design procedure that could reduce the traditional dependence on empirical results in the shell design process. KEYWORDS: high-fidelity nonlinear structural analysis, composite shells, shell stability, initial imperfections
The shell vasculature of Trachemys turtles investigated by modern 3D imaging techniques
DEFF Research Database (Denmark)
Hansen, Kasper; Thygesen, Jesper; Nielsen, Tobias Wang
Many freshwater turtles are extremely tolerant to the lack of oxygen and can survive the winter submerged in anoxic mud in ice-covered lakes. The pronounced anoxia-tolerance resides with a considerable depression of cellular metabolism and the ability to use the shell to buffer the acidosis arising...... from anaerobic metabolism (1). Infusion of microspheres has shown that the shell receives almost half of the cardiac output in turtles made anoxic at low temperatures (2). However, the vasculature of the turtle shell remains to be described. To visualise the vasculature within the carapace and plastron...... of the turtle Trachemys scripta, we perfused terminally anaesthetised turtles with different contrast enhancing agents (Microfil [lead n/a]), barium sulphate [250 mg/kg], and iodine [15-250 mg/kg]), and the animals were then scanned by both single source as well as dual energy Computed Tomographic systems...
Ingestion of six cylindrical and four button batteries
DEFF Research Database (Denmark)
Nielsen, Simon U; Rasmussen, Morten; Hoegberg, Lotte C G
2010-01-01
We report a suicidal ingestion of six cylindrical and four button batteries, in combination with overdosed prescription medicine and smoking of cannabis.......We report a suicidal ingestion of six cylindrical and four button batteries, in combination with overdosed prescription medicine and smoking of cannabis....
Settling of a cylindrical particle in a stagnant fluid
DEFF Research Database (Denmark)
Sørensen, Henrik; Rosendahl, Lasse; Yin, Chungen
2007-01-01
The objective of this work is to collect data and develop models for cylindrical particles which could be used in numerical multiphase flow modeling. Trajectories of cylindrical particles settling in stagnant water are filmed from two directions in order to derive detailed information on their mo...
Cylindrical and spherical dust-acoustic wave modulations in dusty ...
Indian Academy of Sciences (India)
The nonlinear wave modulation of planar and non-planar (cylindrical and spherical) dust-acoustic waves (DAW) propagating in dusty plasmas, in the presence of non-extensive distributions for ions and electrons is investigated. By employing multiple scales technique, a cylindrically and spherically modified nonlinear ...
Development of the Cylindrical Wire Electrical Discharge Machining Process.
Energy Technology Data Exchange (ETDEWEB)
McSpadden, SB
2002-01-22
Results of applying the wire Electrical Discharge Machining (EDM) process to generate precise cylindrical forms on hard, difficult-to-machine materials are presented. A precise, flexible, and corrosion-resistant underwater rotary spindle was designed and added to a conventional two-axis wire EDM machine to enable the generation of free-form cylindrical geometries. A detailed spindle error analysis identifies the major source of error at different frequency. The mathematical model for the material removal of cylindrical wire EDM process is derived. Experiments were conducted to explore the maximum material removal rate for cylindrical and 2D wire EDM of carbide and brass work-materials. Compared to the 2D wire EDM, higher maximum material removal rates may be achieved in the cylindrical wire EDM. This study also investigates the surface integrity and roundness of parts created by the cylindrical wire EDM process. For carbide parts, an arithmetic average surface roughness and roundness as low as 0.68 and 1.7 {micro}m, respectively, can be achieved. Surfaces of the cylindrical EDM parts were examined using Scanning Electron Microscopy (SEM) to identify the craters, sub-surface recast layers and heat-affected zones under various process parameters. This study has demonstrated that the cylindrical wire EDM process parameters can be adjusted to achieve either high material removal rate or good surface integrity.
Cylindrical and spherical dust-acoustic wave modulations in dusty ...
Indian Academy of Sciences (India)
Abstract. The nonlinear wave modulation of planar and non-planar (cylindrical and spherical) dust-acoustic waves (DAW) propagating in dusty plasmas, in the presence of non-extensive distribu- tions for ions and electrons is investigated. By employing multiple scales technique, a cylindrically and spherically modified ...
Methods for geothermal reservoir detection emphasizing submerged environments
Energy Technology Data Exchange (ETDEWEB)
Case, C.W.; Wilde, P.
1976-05-21
This report has been prepared for the California State Lands Commission to aid them in evaluating exploration programs for geothermal reservoirs, particularly in submerged land environments. Three charts show: (1) a logical progression of specific geologic, geochemical, and geophysical exploration techniques for detecting geothermal reservoirs in various geologic environments with emphasis on submerged lands, (2) various exploration techniques which can be used to develop specific information in geothermal areas, and (3) if various techniques will apply to geothermal exploration according to a detailed geologic classification. A narrative in semi-outline form supplements these charts, providing for each technique; a brief description, advantages, disadvantages, special geologic considerations, and specific references. The specific geologic situation will control the exploration criterion to be used for reservoir detection. General guidelines are established which may be of use in evaluating such a program, but the optimum approach will vary with each situation.
Antitumor activity of submerged biomass of Hericium erinaceus
Avtonomova, A.; Bakanov, A.; Vinokurov, V.; Bukhman, V.; Krasnopolskaya, L.
2011-01-01
Submerged cultivation of Hericium erinaceus in various media has been studied. The yield of biomass was shown to depend mainly on the carbon source, whereas the content of watersoluble polysaccharides depended primarily on the nitrogen source. Using optimal medium composition, the biomass yield of 22-23 g/l in 7 days was achieved. The antitumor activity was studied in vivo with using 2 tumor strains. The inhibition ratio of tumor in these experience reached 86%. An exposure of mice with tumor...
Submerged beachrock preservation in the context of wave ravinement
Pretorius, Lauren; Green, Andrew N.; Andrew Cooper, J.
2018-02-01
This study examines a Holocene-aged submerged shoreline, Limestone Reef, located in the shallow subtidal zone of South Africa's east coast. It comprises an elongate, coast-oblique, slab-like outcrop of beachrock situated above the contemporary fair-weather wave base. It is currently undergoing mechanical disintegration. Its unique and rare preservation in a high-energy setting affords an opportunity to examine the mechanical processes occurring during wave ravinement associated with rising sea level. The submerged shoreline and the adjacent shoreface were examined using high-resolution seismic reflection, side-scan sonar and shallow-water multibeam echosounding techniques. Limestone Reef rests on top of unconsolidated Holocene deposits. The structure's surface is characterised by reef-perpendicular gullies with rubble derived from the slab fringing its seaward edge. Limestone Reef slopes gently seawards and has a steep landward-facing edge where gullies are most prominently developed. Teardrop-shaped rippled scour depressions, marked by high backscatter, are located seawards of the submerged shoreline. These elongate in a seaward direction and are filled with bioclastic gravels and residual rubble from Limestone Reef. The gullies in the upstanding structure are indicative of wave plucking and abrasion of the shoreline. The material exposed by the rippled scour depressions is identical to that comprising the postglacial ravinement surface identified in the offshore stratigraphy. These deposits are considered to represent the contemporary, actively forming wave ravinement surface. The results suggest that wave ravinement of submerged shorelines is a discontinuous process dominated by the seaward entrainment of material from its landward edge controlled by high-energy drawback during storm surges. The ravinement process appears to operate at the seasonal scale and averages out over the long-term millennial scale for the continuous surface.
Submerged Pagodas of Mahabalipuram - Study based on underwater investigations
Digital Repository Service at National Institute of Oceanography (India)
Sundaresh; Gaur, A.S.; Tripati, S.; Vora, K.H.; Rao, K.M.
- gested that this place could have served as an ancient port (Dayalan, 1992). Mahabalipuram was well known to earlier mariners as 'Seven Pagodas' since the 1 7h century AD. it is generally believed that out of 7 temples originally con- structed, all... based on the local traditions and available literature. The local tradition and the people of Mahabalipuram believe that five temples similar to the Shore Temple have been submerged in the sea. On the basis of local traditions Ancient Tamil...
Instrumentation, control, and automation for submerged anaerobic membrane bioreactors
Robles Martínez, Ángel; Durán Pinzón, Freddy; Ruano García, María Victoria; Ribes Bertomeu, José; Rosado Muñoz, Alfredo; SECO TORRECILLAS, AURORA; Ferrer, J.
2015-01-01
A submerged anaerobic membrane bioreactor (AnMBR) demonstration plant with two commercial hollow-fibre ultrafiltration systems (PURON® , Koch Membrane Systems, PUR-PSH31) was designed and operated for urban wastewater treatment. An instrumentation, control, and automation (ICA) system was designed and implemented for proper process performance. Several single-input-single-output (SISO) feedback control loops based on conventional on off and PID algorithms were implemented to control the follo...
Dehbashi, Reza; Shahabadi, Mahmoud
2013-12-01
The commonly used coordinate transformation for cylindrical cloaks is generalized. This transformation is utilized to determine an anisotropic inhomogeneous diagonal material tensors of a shell type cloak for various material types, i.e., double-positive (DPS: ɛ, μ > 0), double-negative (DNG: ɛ, μ cloaking for various material types, a rigorous analysis is performed. It is shown that perfect cloaking will be achieved for same type material for the cloak and its surrounding medium. Moreover, material losses are included in the analysis to demonstrate that perfect cloaking for lossy materials can be achieved for identical loss tangent of the cloak and its surrounding material. Sensitivity of the cloaking performance to losses for different material types is also investigated. The obtained analytical results are verified using a Finite-Element computational analysis.
Hot electrons and electron-phonon coupling in a cylindrical nanoshell.
Qu, Shi-Xian; Zhao, Ya-Ni; Zhang, Lin; Geller, Michael R
2011-11-01
We use a standard model for the low-temperature electron-phonon interaction in metals to calculate the rate of thermal energy transfer between electrons and acoustic phonons in suspended metallic nanoshells. The electrons are treated as three-dimensional and noninteracting, whereas the vibrational modes are that of an thin cylindrical elastic shell of radius R with a free surface and thickness h. Disorder is neglected. The temperature dependence of the thermal power is obtained analytically for this model, and a crossover from the T3 dependence expected for one-dimensional phonons to a T3/(1 - v2) + 9gammaT4/[T*(1 - v2)(3/2)] dependence is obtained.
Implosion of multilayered cylindrical targets driven by intense heavy ion beams.
Piriz, A R; Portugues, R F; Tahir, N A; Hoffmann, D H H
2002-11-01
An analytical model for the implosion of a multilayered cylindrical target driven by an intense heavy ion beam has been developed. The target is composed of a cylinder of frozen hydrogen or deuterium, which is enclosed in a thick shell of solid lead. This target has been designed for future high-energy-density matter experiments to be carried out at the Gesellschaft für Schwerionenforschung, Darmstadt. The model describes the implosion dynamics including the motion of the incident shock and the first reflected shock and allows for calculation of the physical conditions of the hydrogen at stagnation. The model predicts that the conditions of the compressed hydrogen are not sensitive to significant variations in target and beam parameters. These predictions are confirmed by one-dimensional numerical simulations and thus allow for a robust target design.
Fast calculation method for computer-generated cylindrical holograms.
Yamaguchi, Takeshi; Fujii, Tomohiko; Yoshikawa, Hiroshi
2008-07-01
Since a general flat hologram has a limited viewable area, we usually cannot see the other side of a reconstructed object. There are some holograms that can solve this problem. A cylindrical hologram is well known to be viewable in 360 deg. Most cylindrical holograms are optical holograms, but there are few reports of computer-generated cylindrical holograms. The lack of computer-generated cylindrical holograms is because the spatial resolution of output devices is not great enough; therefore, we have to make a large hologram or use a small object to fulfill the sampling theorem. In addition, in calculating the large fringe, the calculation amount increases in proportion to the hologram size. Therefore, we propose what we believe to be a new calculation method for fast calculation. Then, we print these fringes with our prototype fringe printer. As a result, we obtain a good reconstructed image from a computer-generated cylindrical hologram.
On the submerging of a spherical intruder into granular beds
Wu, Chuan-Yu; Zhang, Ling; Chen, Lan
2017-06-01
Granular materials are complex systems and their mechanical behaviours are determined by the material properties of individual particles, the interaction between particles and the surrounding media, which are still incompletely understood. Using an advanced discrete element method (DEM), we simulate the submerging process of a spherical projectile (an intruder) into granular materials of various properties with a zero penetration velocity (i.e. the intruder is touching the top surface of the granular bed and released from stationary) and examine its settling behaviour. By systematically changing the density and size of the intruder and the particle density (i.e. the density of the particles in the granular bed), we find that the intruder can sink deep into the granular bed even with a zero penetration velocity. Furthermore, we confirm that under certain conditions the granular bed can behave like a Newtonian liquid and the submerging intruder can reach a constant velocity, i.e. the terminal velocity, identical to the settling of a sphere in a liquid, as observed experimentally. A mathematical model is also developed to predict the maximum penetration depth of the intruder. The model predictions are compared with experimental data reported in the literature,good agreement was obtained, demonstrating the model can accurately predict the submerging behaviour of the intruder in the granular media.
Research efforts for detection and recovery of submerged oil
Energy Technology Data Exchange (ETDEWEB)
Hansen, K. [United States Coast Guard, Groton, CT (United States). Research and Development Center
2009-07-01
Submerged oil can sink and destroy shellfish and other marine populations in addition to causing closure of water intakes at industrial facilities and power plants. However, current methods to find and recover oil from spills involving submerged oil are inadequate. The underwater environment presents major challenges such as poor visibility, difficulty in tracking oil spill movement, colder temperatures, inadequate containment methods and problems with the equipment's interaction with water. This paper reported on a multi-year project launched by the Research and Development Center of the United States Coast Guard to develop a complete approach for spills of submerged oil. The project involved detection technologies and recovery methods for oil on the bottom of any body of water. Proof of concept (POC) and prototype tests of potential detection technologies were evaluated during tests at the Ohmsett facility in Leonardo, New Jersey. The technologies included sonar, laser fluorometry, real-time mass spectrometry and in-situ fluorometry. This paper described the development of a complete specification for an integrated recovery system along with a plan for future development. 9 refs., 2 tabs., 11 figs.
Measurement of Submerged Oil/Gas Leaks using ROV Video
Shaffer, Franklin; de Vera, Giorgio; Lee, Kenneth; Savas, Ömer
2013-11-01
Drilling for oil or gas in the Gulf of Mexico is increasing rapidly at depths up to three miles. The National Commission on the Deepwater Horizon Oil Leak concluded that inaccurate estimates of the leak rate from the Deepwater Horizon caused an inadequate response and attempts to cap the leak to fail. The first response to a submerged oil/gas leak will be to send a Remotely Operated Vehicle (ROV) down to view the leak. During the response to the Deepwater Horizon crisis, the authors Savas and Shaffer were members of the Flow Rate Technical Group's Plume Team who used ROV video to develop the FRTG's first official estimates of the oil leak rate. Savas and Shaffer developed an approach using the larger, faster jet features (e.g., turbulent eddies, vortices, entrained particles) in the near-field developing zone to measure discharge rates. The authors have since used the Berkeley Tow Tank to test this approach on submerged dye-colored water jets and compressed air jets. Image Correlation Velocimetry has been applied to measure the velocity of visible features. Results from tests in the Berkeley Tow Tank and submerged oil jets in the OHMSETT facility will be presented.
Production of Alpha Amylase by Bacillus cereus in Submerged Fermentation
Directory of Open Access Journals (Sweden)
Helen H. Raplong
2014-09-01
Full Text Available Microorganisms have the ability to secrete enzymes when they are grown in the presence of certain substrates. Amylases are among the most important industrial enzymes and are of great significance in biotechnological studies. Bacteria belonging to the genus Bacillus were isolated using mannitol egg yolk polymyxin B (MYP agar a highly selective media for Bacillus cereus isolation. The isolates were tested for α-amylase production on nutrient agar supplemented with starch and in submerged fermentation. The bacteria isolated and identified (using the Microgen Bacillus identification kit were all Bacillus cereus and SB2 had the largest zone of hydrolysis of 12mm on nutrient agar supplemented with starch as well as the highest enzyme activity of 1.62U/ml. Amylase activity of 2.56U/ml was obtained after 24 hours incubation in submerged fermentation. When amylase enzyme production parameters where optimized, maximum amylase activity was obtained at a pH of 6.5, temperature of 350C, incubation time of 24 hours and 4% inoculums concentration. Bacillus cereus SB2 is a potential isolate for alpha-amylase production with soluble starch as the sole carbon source in submerged fermentation.
On the submerging of a spherical intruder into granular beds
Directory of Open Access Journals (Sweden)
Wu Chuan-Yu
2017-01-01
Full Text Available Granular materials are complex systems and their mechanical behaviours are determined by the material properties of individual particles, the interaction between particles and the surrounding media, which are still incompletely understood. Using an advanced discrete element method (DEM, we simulate the submerging process of a spherical projectile (an intruder into granular materials of various properties with a zero penetration velocity (i.e. the intruder is touching the top surface of the granular bed and released from stationary and examine its settling behaviour. By systematically changing the density and size of the intruder and the particle density (i.e. the density of the particles in the granular bed, we find that the intruder can sink deep into the granular bed even with a zero penetration velocity. Furthermore, we confirm that under certain conditions the granular bed can behave like a Newtonian liquid and the submerging intruder can reach a constant velocity, i.e. the terminal velocity, identical to the settling of a sphere in a liquid, as observed experimentally. A mathematical model is also developed to predict the maximum penetration depth of the intruder. The model predictions are compared with experimental data reported in the literature,good agreement was obtained, demonstrating the model can accurately predict the submerging behaviour of the intruder in the granular media.
Shell morphology and Raman spectra of epitaxial Ge-SixGe1-x and Si-SixGe1-x core-shell nanowires
Wen, Feng; Dillen, David C.; Kim, Kyounghwan; Tutuc, Emanuel
2017-06-01
We investigate the shell morphology and Raman spectra of epitaxial Ge-SixGe1-x and Si-SixGe1-x core-shell nanowire heterostructures grown using a combination of a vapor-liquid-solid (VLS) growth mechanism for the core, followed by in-situ epitaxial shell growth using ultra-high vacuum chemical vapor deposition. Cross-sectional transmission electron microscopy reveals that the VLS growth yields cylindrical Ge, and Si nanowire cores grown along the ⟨111⟩, and ⟨110⟩ or ⟨112⟩ directions, respectively. A hexagonal cross-sectional morphology is observed for Ge-SixGe1-x core-shell nanowires terminated by six {112} facets. Two distinct morphologies are observed for Si-SixGe1-x core-shell nanowires that are either terminated by four {111} and two {100} planes associated with the ⟨110⟩ growth direction or four {113} and two {111} planes associated with the ⟨112⟩ growth direction. We show that the Raman spectra of Si- SixGe1-x are correlated with the shell morphology thanks to epitaxial growth-induced strain, with the core Si-Si mode showing a larger red shift in ⟨112⟩ core-shell nanowires compared to their ⟨110⟩ counterparts. We compare the Si-Si Raman mode value with calculations based on a continuum elasticity model coupled with the lattice dynamic theory.
Surface energy effect on free vibration of nano-sized piezoelectric double-shell structures
Fang, Xue-Qian; Zhu, Chang-Song; Liu, Jin-Xi; Liu, Xiang-Lin
2018-01-01
Combining Goldenveizer-Novozhilov shell theory, thin plate theory and electro-elastic surface theory, the size-dependent vibration of nano-sized piezoelectric double-shell structures under simply supported boundary condition is presented, and the surface energy effect on the natural frequencies is discussed. The displacement components of the cylindrical nano-shells and annular nano-plates are expanded as the superposition of standard Fourier series based on Hamilton's principle. The total stresses with consideration of surface energy effect are derived, and the total energy function is obtained by using Rayleigh-Ritz energy method. The free vibration equation is solved, and the natural frequency is analyzed. In numerical examples, it is found that the surface elastic constant, piezoelectric constant and surface residual stress show different effects on the natural frequencies. The effect of surface piezoelectric constant is the maximum. The effect of dimensions of the double-shell under different surface material properties is also examined.
Wang, Kai; Fan, Zhenfang; Wang, Dongya; Wang, Yanyan; Pan, Yao; Qu, Tianliang; Xu, Guangming
2016-10-01
The existence of mode deflection angle in the cylindrical resonator gyroscope (CRG) leads to the signal drift on the detecting nodes of the gyro vibration and significantly decreases the performance of the CRG. Measuring the mode deflection angle efficiently is the foundation of tuning for the imperfect cylindrical shell resonator. In this paper, an optical method based on the measuring gyroscopic resonator's vibration amplitude with the laser Doppler vibrometer and an electrical method based on measuring the output voltage of the electrodes on the resonator are both presented to measure the mode deflection angle. Comparative experiments were implemented to verify the methodology and the results show that both of the two methods could recognize the mode deflection angle efficiently. The precision of the optical method relies on the number and position of testing points distributed on the resonator. The electrical method with simple circuit shows high accuracy of measuring in a less time compared to the optical method and its error source arises from the influence of circuit noise as well as the inconsistent distribution of the piezoelectric electrodes.
From shell logs to shell scripts
Jacobs, Nico; Blockeel, Hendrik
2001-01-01
Analysing the use of a Unix command shell is one of the classic applications in the domain of adaptive user interfaces and user modelling. Instead of trying to predict the next command from a history of commands, we automatically produce scripts that automate frequent tasks. For this we use an ILP association rule learner. We show how to speedup the learning task by dividing it into smaller tasks, and the need for a preprocessing phase to detect frequent subsequences in the data. We illustrat...
Converging cylindrical shocks in ideal magnetohydrodynamics
Pullin, D. I.
2014-09-01
We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R = √μ0/p0 I/(2π) where I is the current, μ0 is the permeability, and p0 is the pressure ahead of the shock. For shocks initiated at r ≫ R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The diverging magnetic field then
Multi-parameter actuation of a neutrally stable shell: a flexible gear-less motor.
Hamouche, W; Maurini, C; Vidoli, S; Vincenti, A
2017-08-01
We have designed and tested experimentally a morphing structure consisting of a neutrally stable thin cylindrical shell driven by a multi-parameter piezoelectric actuation. The shell is obtained by plastically deforming an initially flat copper disc, so as to induce large isotropic and almost uniform inelastic curvatures. Following the plastic deformation, in a perfectly isotropic system, the shell is theoretically neutrally stable, having a continuous set of stable cylindrical shapes corresponding to the rotation of the axis of maximal curvature. Small imperfections render the actual structure bistable, giving preferred orientations. A three-parameter piezoelectric actuation, exerted through micro-fibre-composite actuators, allows us to add a small perturbation to the plastic inelastic curvature and to control the direction of maximal curvature. This actuation law is designed through a geometrical analogy based on a fully nonlinear inextensible uniform-curvature shell model. We report on the fabrication, identification and experimental testing of a prototype and demonstrate the effectiveness of the piezoelectric actuators in controlling its shape. The resulting motion is an apparent rotation of the shell, controlled by the voltages as in a 'gear-less motor', which is, in reality, a precession of the axis of principal curvature.
The fundamental solution for a consistent complex model of the shallow shell equations
Directory of Open Access Journals (Sweden)
Matthew P. Coleman
1999-09-01
Full Text Available The calculation of the Fourier transforms of the fundamental solution in shallow shell theory ostensibly was accomplished by J. L. Sanders [J. Appl. Mech. 37 (1970, 361-366]. However, as is shown in detail in this paper, the complex model used by Sanders is, in fact, inconsistent. This paper provides a consistent version of Sanders's complex model, along with the Fourier transforms of the fundamental solution for this corrected model. The inverse Fourier transforms are then calculated for the particular cases of the shallow spherical and circular cylindrical shells, and the results of the latter are seen to be in agreement with results appearing elsewhere in the literature.
Hamza, Alex V.; Biener, Juergen; Wild, Christoph; Woerner, Eckhard
2016-11-01
A novel method for fabricating diamond shells is introduced. The fabrication of such shells is a multi-step process, which involves diamond chemical vapor deposition on predetermined mandrels followed by polishing, microfabrication of holes, and removal of the mandrel by an etch process. The resultant shells of the present invention can be configured with a surface roughness at the nanometer level (e.g., on the order of down to about 10 nm RMS) on a mm length scale, and exhibit excellent hardness/strength, and good transparency in the both the infra-red and visible. Specifically, a novel process is disclosed herein, which allows coating of spherical substrates with optical-quality diamond films or nanocrystalline diamond films.
Lee, M. C.; Kendall, J. M., Jr.; Bahrami, P. A.; Wang, T. G.
1986-01-01
Fluid-dynamic and capillary forces can be used to form nearly perfect, very small spherical shells when a liquid that can solidify is passed through an annular die to form an annular jet. Gravity and certain properties of even the most ideal materials, however, can cause slight asymmetries. The primary objective of the present work is the control of this shell formation process in earth laboratories rather than space microgravity, through the development of facilities and methods that minimize the deleterious effects of gravity, aerodynamic drag, and uncontrolled cooling. The spherical shells thus produced can be used in insulation, recyclable filter materials, fire retardants, explosives, heat transport slurries, shock-absorbing armor, and solid rocket motors.
Surface tension and long range corrections of cylindrical interfaces.
Bourasseau, E; Malfreyt, P; Ghoufi, A
2015-12-21
The calculation of the surface tension of curved interfaces has been deeply investigated from molecular simulation during this last past decade. Recently, the thermodynamic Test-Area (TA) approach has been extended to the calculation of surface tension of curved interfaces. In the case of the cylindrical vapour-liquid interfaces of water and Lennard-Jones fluids, it was shown that the surface tension was independent of the curvature of the interface. In addition, the surface tension of the cylindrical interface is higher than that of the planar interface. Molecular simulations of cylindrical interfaces have been so far performed (i) by using a shifted potential, (ii) by means of large cutoff without periodic boundary conditions, or (iii) by ignoring the long range corrections to the surface tension due to the difficulty to estimate them. Indeed, unlike the planar interfaces there are no available operational expressions to consider the tail corrections to the surface tension of cylindrical interfaces. We propose here to develop the long range corrections of the surface tension for cylindrical interfaces by using the non-exponential TA (TA2) method. We also extend the formulation of the Mecke-Winkelmann corrections initially developed for planar surfaces to cylindrical interfaces. We complete this study by the calculation of the surface tension of cylindrical surfaces of liquid tin and copper using the embedded atom model potentials.
Cylindrical isentropic compression by ultrahigh magnetic field
Gu, Zhuowei; Luo, Hao; Zhang, Hengdi; Zhao, Shichao; Tang, Xiaosong; Tong, Yanjin; Song, Zhenfei; Tan, Fuli; Zhao, Jianheng; Sun, Chengwei
2014-05-01
The cylindrical isentropic compression by ultrahigh magnetic field (MC-1) is a kind of unique high energy density technique. It has characters like ultrahigh pressure and low temperature rising, and would have widely used in areas like high pressure physics, new material synthesis and ultrahigh magnetic field physics. The Institute of Fluid Physics, Chinese Academy of Engineering Physics (IFP, CAEP) has begun the experiment since 2011 and a primary experimental device had been set-up. In the experiments, a seed magnetic field of 5 Tesla were set-up first and compressed by a stainless steel liner which is driven by high explosive initiated synchronously. The internal diameter of the liner is 97 mm, and its thickness is 1.5 mm. The movement of liner was recorded optically and a typical turnaround phenomenon was observed. From the photography results the liner was compressed smoothly and evenly and its average velocity was about 5-6 km/s. In the experiment a axial magnetic field of over 1400 Tesla has been recorded. The MC-1 process was numerical simulated by 1D MHD code MC11D and the simulations are in accord with the experiments.
Technology Selections for Cylindrical Compact Fabrication
Energy Technology Data Exchange (ETDEWEB)
Jeffrey A. Phillips
2010-10-01
A variety of process approaches are available and have been used historically for manufacture of cylindrical fuel compacts. The jet milling, fluid bed overcoating, and hot press compacting approach being adopted in the U.S. AGR Fuel Development Program for scale-up of the compacting process involves significant paradigm shifts from historical approaches. New methods are being pursued because of distinct advantages in simplicity, yield, and elimination of process mixed waste. Recent advances in jet milling technology allow simplified dry matrix powder preparation. The matrix preparation method is well matched with patented fluid bed powder overcoating technology recently developed for the pharmaceutical industry and directly usable for high density fuel particle matrix overcoating. High density overcoating places fuel particles as close as possible to their final position in the compact and is matched with hot press compacting which fully fluidizes matrix resin to achieve die fill at low compacting pressures and without matrix end caps. Overall the revised methodology provides a simpler process that should provide very high yields, improve homogeneity, further reduce defect fractions, eliminate intermediate grading and QC steps, and allow further increases in fuel packing fractions.
Optimal attitude corrections for cylindrical spacecraft
Zanardi, M. C.; Santos, R. M. K.; da Silva Fernandes, S.
2003-04-01
A first order analytical model for optimal small amplitude attitude maneuvers of spacecraft with cylindrical symmetry in an elliptical orbits is presented. The optimization problem is formulated as a Mayer problem with the control torques provided by a power limited propulsion system. The state is defined by Serret-Andoyer's variables and the control by the components of the propulsive torques. The Pontryagin Maximum Principle is applied to the problem and the optimal torques are given explicitly in Serret-Andoyer's variables and their adjoints. For small amplitude attitude maneuvers, the optimal Hamiltonian function is linearized around a reference attitude. A complete first order analytical solution is obtained by simple quadrature and is expressed through a linear algebraic system involving the initial values of the adjoint variables. A numerical solution is obtained by taking the Euler angles formulation of the problem, solving the two-point boundary problem through the shooting method, and, then, determining the Serret-Andoyer variables through Serret-Andoyer transformation. Numerical results show that the first order solution provides a good approximation to the optimal control law and also that is possible to establish an optimal control law for the artificial satellite's attitude.
Residence time distribution of a cylindrical microreactor.
Hsu, Jyh-Ping; Wei, Tzu-Hsuan
2005-05-12
The residence time distribution for the flow of liquid reactants containing electrolytes in a cylindrical microreactor is derived under the conditions of constant surface potential and negligible end effects. The influences of the key parameters, including the thickness of the double layer, the strength of the applied electric field, and the magnitude of the applied pressure gradient, on the behavior of residence time distribution are discussed. The results obtained provide necessary information for the design and optimization of microreactors which involve liquid electrolyte reactants. The results of the numerical simulation reveal that a thin double layer, a strong applied electric field, and a greater applied pressure gradient lead to a faster fluid flow and, therefore, a short residence time. We show that if kappaa residence time distribution can be approximated by that for the case of a laminar flow, and if kappaa >/= 500, the residence time distribution can be approximated by that for the case of a plug flow, with kappa and a being the reciprocal Debye length and the radius of the microreactor, respectively.
Cylindrical Optic Polishing Dwell Time Optimization
Waluschka, Eugene
2000-01-01
The Constellation-X x-ray telescope consists of replicated grazing incidence optics. The polishing of the "master' mandrel is accomplished by moving a polishing tool along a helical path on the surface of this almost cylindrical surface. The measurement of the surface is, however, performed along "axial" scan lines which intercept this helical path. This approach to polishing and measuring permits a relatively simple scheme to be implemented for the determination of the optimal dwell times of the polishing tool. These optimal dwell times are determined by a deconvolution which approaches the problem as a linear programming problem and uses the simplex method. This approach maximizes the amount of material removed at any point subject to inequality constraints. The effects of using these "optimum" dwell times is to significantly improve the "tools" effectiveness at removing the higher spatial frequencies while staying (strictly) within the bounds and constraints imposed by the hardware. In addition the "ringing" at the edges of the optic, frequently present in deconvolution problems, is completely eliminated.
Jet Mixing in a Reacting Cylindrical Crossflow
Leong, M. Y.; Samuelsen, G. S.; Holdeman, J. D.
1995-01-01
This paper addresses the mixing of air jets into the hot, fuel-rich products of a gas turbine primary zone. The mixing, as a result, occurs in a reacting environment with chemical conversion and substantial heat release. The geometry is a crossflow confined in a cylindrical duct with side-wall injection of jets issuing from round orifices. A specially designed reactor, operating on propane, presents a uniform mixture without swirl to mixing modules consisting of 8, 9, 10, and 12 holes at a momentum-flux ratio of 57 and a jet-to-mainstream mass-flow ratio of 2.5. Concentrations of O2, CO2, CO, and HC are obtained upstream, downstream, and within the orifice plane. O2 profiles indicate jet penetration while CO2, CO, and HC profiles depict the extent of reaction. Jet penetration is observed to be a function of the number of orifices and is found to affect the mixing in the reacting system. The results demonstrate that one module (the 12-hole) produces near-optimal penetration defined here as a jet penetration closest to the module half-radius, and hence the best uniform mixture at a plane one duct radius from the orifice leading edge.
On Hydrodynamic Instabilities in Cylindrical Geometry
Proano, Erik; Rollin, Bertrand
2017-11-01
Recent research has suggested that hydrodynamic instabilities induced mixing is one of the last major hurdles toward achieving optimum conditions for ignition in confined fusion approaches for energy production. We leave aside the complexities of multiple interacting physics that lead to a fusion target ignition to be able to focus on understanding the development of these hydrodynamic instabilities, namely Richtmyer-Meshkov and Rayleigh-Taylor, in the context of a converging geometry. The problem is reformulated into the cleaner case of a cylindrical shock wave imploding onto a pocket of Sulfur Hexafluoride immersed in air. This numerical experiment aims at characterizing qualitatively and quantitatively the relation between the instabilities initial conditions and their development until late time. Starting from carefully designed single- and multimode disturbances at the initial density interface, our simulations track the evolution of the mixing layer through successive occurrences of the Richtmyer-Meshkov and Rayleigh-Taylor instabilities. Evolution of the mixing zone width and growth rate are presented for selected initial conditions, along with a quantification of mixing. Also, the effect of the converging shock strength is discussed.
Antioxidant Properties of the Edible Basidiomycete Armillaria mellea in Submerged Cultures
Lung, Ming-Yeou; Chang, Yu-Cheng
2011-01-01
Antioxidant components, ascorbic acid, total flavonoids and total phenols are produced effectively by Armillaria mellea submerged cultures. Dried mycelia and mycelia-free broths obtained by A. mellea submerged cultures are extracted with methanol and hot water and investigated for antioxidant properties. Methanolic extracts from dried mycelia (MEM) and mycelia-free broth (MEB) and hot water extracts from dried mycelia (HWEM) by A. mellea submerged cultures show good antioxidant properties as ...
Song, Kun; Cui, Yichong; Zhang, Xijin; Pan, Yingji; Xu, Junli; Xu, Kaiqin; Da, Liangjun
2017-01-01
Abstract Water eutrophication creates unfavorable environmental conditions for submerged macrophytes. In these situations, biotic interactions may be particularly important for explaining and predicting the submerged macrophytes occurrence. Here, we evaluate the roles of biotic interactions in predicting spatial occurrence of submerged macrophytes in 1959 and 2009 for Dianshan Lake in eastern China, which became eutrophic since the 1980s. For the four common species occurred in 1959 and 2009,...
NIF Double Shell outer/inner shell collision experiments
Merritt, E. C.; Loomis, E. N.; Wilson, D. C.; Cardenas, T.; Montgomery, D. S.; Daughton, W. S.; Dodd, E. S.; Desjardins, T.; Renner, D. B.; Palaniyappan, S.; Batha, S. H.; Khan, S. F.; Smalyuk, V.; Ping, Y.; Amendt, P.; Schoff, M.; Hoppe, M.
2017-10-01
Double shell capsules are a potential low convergence path to substantial alpha-heating and ignition on NIF, since they are predicted to ignite and burn at relatively low temperatures via volume ignition. Current LANL NIF double shell designs consist of a low-Z ablator, low-density foam cushion, and high-Z inner shell with liquid DT fill. Central to the Double Shell concept is kinetic energy transfer from the outer to inner shell via collision. The collision determines maximum energy available for compression and implosion shape of the fuel. We present results of a NIF shape-transfer study: two experiments comparing shape and trajectory of the outer and inner shells at post-collision times. An outer-shell-only target shot measured the no-impact shell conditions, while an `imaging' double shell shot measured shell conditions with impact. The `imaging' target uses a low-Z inner shell and is designed to perform in similar collision physics space to a high-Z double shell but can be radiographed at 16keV, near the viable 2DConA BL energy limit. Work conducted under the auspices of the U.S. DOE by LANL under contract DE-AC52-06NA25396.
Electromagnetic Cylindrical Transparent Devices with Irregular Cross Section
Directory of Open Access Journals (Sweden)
C. Yang
2010-04-01
Full Text Available Electromagnetic transparent device is very important for antenna protection. In this paper, the material parameters for the cylindrical transparent devices with arbitrary cross section are developed based on the coordinate transformation. The equivalent two-dimensional (2D transparent devices under TE plane and cylindrical wave irradiation is designed and studied by full-wave simulation, respectively. It shows that although the incident waves are distorted in the transformation region apparently, they return to the original wavefronts when passing through the device. All theoretical and numerical results validate the material parameters for the cylindrical transparent devices with arbitrary cross section we developed.
Band structure of wurtzite quantum dots with cylindrical symmetry
Voon, Lok Lew Yan; Galeriu, Calin; Lassen, Benny
2005-03-01
A six-band k .p theory for wurtzite semiconductor nanostructures with cylindrical symmetry will be presented. Our work extends the formulation of Vahala and Sercel [Phys. Rev. Lett. 65, 239 (1990)] to the Rashba-Sheka-Pikus Hamiltonian for wurtzite semiconductors, without the need for the axial approximation. Results comparing this new formulation for studying the electronic structure of wurzite GaN and CdS cylindrical quantum dots with the conventional formulation will be shown; our formulation is computationally superior. An application to the search for level crossing in the valence band of cylindrical quantum rods as a function of aspect ratio will be given. Supported by NSF CAREER award.
Directory of Open Access Journals (Sweden)
Sung-Hee Kim
2012-06-01
Full Text Available Hull Mounted Sonar (HMS is a long range submerged vehicle's hull-mounted passive sonar system which detects low-frequency noise caused by machineries of enemy ships or submerged vehicles. The HMS needs a sound absorption /insulation multi-layer structure to shut out the self-noise from own machineries and to amplify signals from outside. Therefore, acoustic analysis of the multi-layer system should be performed when the HMS is designed. This paper simplified the HMS multi-layer system to be an infinite planar multi-layer model. Also, main excitations that influence the HMS were classified into mechanical, plane wave and turbulent flow excitation, and the investigations for each excitation were performed for various models. Stiffened multi-layer analysis for mechanical excitation and general multi-layer analysis for turbulent flow excitation were developed. The infinite planar multi-layer analysis was expected to be more useful for preliminary design stage of HMS system than the infinite cylindrical model because of short analysis time and easiness of parameter study.
GigaUnit Transplant System: A New Mechanical Tool for Transplanting Submerged Aquatic Vegetation
National Research Council Canada - National Science Library
Shafer, Deborah J
2008-01-01
Submerged aquatic vegetation (SAV) performs many important ecosystem functions, including wave attenuation and sediment stabilization, water quality improvement, primary production, food web support for secondary consumers...
Role of Genome in the Formation of Conical Retroviral Shells
Erdemci-Tandogan, Gonca; van der Schoot, Paul; Zandi, Roya
2016-01-01
Human immunodeficiency virus (HIV) capsid proteins spontaneously assemble around the genome into a protective protein shell called the capsid, which can take on a variety of shapes broadly classified as conical, cylindrical and irregular. The majority of capsids seen in in vivo studies are conical in shape, while in vitro experiments have shown a preference for cylindrical capsids. The factors involved in the selection of the unique shape of HIV capsids are not well understood, and in particular the impact of RNA on the formation of the capsid is not known. In this work, we study the role of the genome and its interaction with the capsid protein by modeling the genomic RNA through a mean-field theory. Our results show that the confinement free energy for a homopolymeric model genome confined in a conical capsid is lower than that in a cylindrical capsid, at least when the genome does not interact with the capsid, which seems to be the case in in vivo experiments. Conversely, the confinement free energy for th...
Temporal structures in shell models
DEFF Research Database (Denmark)
Okkels, F.
2001-01-01
The intermittent dynamics of the turbulent Gledzer, Ohkitani, and Yamada shell-model is completely characterized by a single type of burstlike structure, which moves through the shells like a front. This temporal structure is described by the dynamics of the instantaneous configuration of the shell...
ir.ing Ruud Thelosen
2011-01-01
Shell heeft zich in de Tweede Kamer moeten verantwoorden voor haar activiteiten in Nigeria. Daarnaast loopt er ook een rechtzaak tegen Shell aangespannen door Milieudefensie namens een groepje gedupeerde Nigeriaanse boeren en viseers. In de VS heeft Shell al een megaboete moeten betalen.
Temporal Structures in Shell Models
Okkels, Fridolin
2000-01-01
The intermittent dynamics of the turbulent GOY shell-model is characterised by a single type of burst-like structure, which moves through the shells like a front. This temporal structure is described by the dynamics of the instantaneous configuration of the shell-amplitudes revealing a approximative chaotic attractor of the dynamics.
External Cylindrical Nozzle with Controlled Vacuum
Directory of Open Access Journals (Sweden)
V. N. Pil'gunov
2015-01-01
Full Text Available There is a developed design of the external cylindrical nozzle with a vacuum camera. The paper studies the nozzle controllability of flow rate via regulated connection of the evacuated chamber to the atmosphere through an air throttle. Working capacity of the nozzle with inlet round or triangular orifice are researched. The gap is provided in the nozzle design between the external wall of the inlet orifice and the end face of the straight case in the nozzle case. The presented mathematical model of the nozzle with the evacuated chamber allows us to estimate the expected vacuum amount in the compressed section of a stream and maximum permissible absolute pressure at the inlet orifice. The paper gives experimental characteristics of the fluid flow process through the nozzle for different values of internal diameter of a straight case and an extent of its end face remoteness from an external wall of the inlet orifice. It estimates how geometry of nozzle constructive elements influences on the volume flow rate. It is established that the nozzle capacity significantly depends on the shape of inlet orifice. Triangular orifice nozzles steadily work in the mode of completely filled flow area of the straight case at much more amounts of the limit pressure of the flow. Vacuum depth in the evacuated chamber also depends on the shape of inlet orifice: the greatest vacuum is reached in a nozzle with the triangular orifice which 1.5 times exceeds the greatest vacuum with the round orifice. Possibility to control nozzle capacity through the regulated connection of the evacuated chamber to the atmosphere was experimentally estimated, thus depth of flow rate regulation of the nozzle with a triangular orifice was 45% in comparison with 10% regulation depth of the nozzle with a round orifice. Depth of regulation calculated by a mathematical model appeared to be much more. The paper presents experimental dependences of the flow coefficients of nozzle input orifice
Investigation of HE driven cylindrical liner
Energy Technology Data Exchange (ETDEWEB)
Tan, Tai-Ho
1995-03-01
We developed a technique that can compress most materials to densities much higher than their original values and shock them hard enough to undergo phase changes to various partially ionized states. The process involves using high explosives to drive a thin cylindrical liner so that it will progressively implode and converge along the axis at very high velocity. The device is simple yet versatile. Its configuration is ideally suited as a compact laboratory for the investigation of the behavior of dense media under extreme conditions. Code simulations show that liners made from most metals can be successfully imploded to converge on axis, producing over 10 MB pressure. For example, a 2D hydrocode calculation predicts that in a simple configuration where a hollow core PBX-9501 explosive cylinder is corner initiated to drive a thin seamless 304 SS tubing, the final convergence velocity can exceed 1 cm/[Ls to produce a 15 MB pressure at impact as the density increases to 19.5 g/cc. The temperature from shock heating rises rapidly above 8 eV, and the result is a combination of radiation and plasma emissions. We have carried out several experiments with a wide array of diagnostics to investigate the implosion dynamics and final state interaction phenomena, and the results are compared with the code predictions. Radiographs of the liner implosion strongly indicate that the hydrodynamic processes are well behaved and calculable. Temperature measurement from the optical radiation is generally consistent with the code prediction. The velocity of the plasma front is measured by using optical pins and fast framing photography, and is found to lie between 11--17 cm/{mu}s. Fast framing photographs were taken with the aid of self luminous light to observe the evacuated chamber inside the imploding liner. The experimental results and their comparison with the calculation are discussed.
Restoring Ecological Function to a Submerged Salt Marsh
Stagg, C.L.; Mendelssohn, I.A.
2010-01-01
Impacts of global climate change, such as sea level rise and severe drought, have altered the hydrology of coastal salt marshes resulting in submergence and subsequent degradation of ecosystem function. A potential method of rehabilitating these systems is the addition of sediment-slurries to increase marsh surface elevation, thus ameliorating effects of excessive inundation. Although this technique is growing in popularity, the restoration of ecological function after sediment addition has received little attention. To determine if sediment subsidized salt marshes are functionally equivalent to natural marshes, we examined above- and belowground primary production in replicated restored marshes receiving four levels of sediment addition (29-42 cm North American Vertical Datum of 1988 [NAVD 88]) and in degraded and natural ambient marshes (4-22 cm NAVD 88). Moderate intensities of sediment-slurry addition, resulting in elevations at the mid to high intertidal zone (29-36 cm NAVD 88), restored ecological function to degraded salt marshes. Sediment additions significantly decreased flood duration and frequency and increased bulk density, resulting in greater soil drainage and redox potential and significantly lower phytotoxic sulfide concentrations. However, ecological function in the restored salt marsh showed a sediment addition threshold that was characterized by a decline in primary productivity in areas of excessive sediment addition and high elevation (>36 cm NAVD 88). Hence, the addition of intermediate levels of sediment to submerging salt marshes increased marsh surface elevation, ameliorated impacts of prolonged inundation, and increased primary productivity. However, too much sediment resulted in diminished ecological function that was equivalent to the submerged or degraded system. ?? 2010 Society for Ecological Restoration International.
Enhanced Sorbitol Production under Submerged Fermentation using Lactobacillus plantarum
Directory of Open Access Journals (Sweden)
Khan Nadiya Jan
2017-04-01
Full Text Available Background and Objective: Sorbitol is a non-toxic and slightly hygroscopic compound with different applications. Zymomonas mobiles produces sorbitol from sucrose or mixtures of glucose and fructose (formation is coupled with the dehydrogenation of glucose to glucono-δ- lactone. Recombinant Zymomonas mobilis may produce sorbitol and gluconic acid from glucose and fructose using different divalent metal ions with reduced the ethanol yield andsignificantly increased yield of sorbitol. Current study envisaged to alter the media components, physical process parameters and supplementation of amino acids for enhanced sorbitol production.Material and Methods: Several process variables were evaluated on sorbitol production including carbon sources (glucose, fructose, maltose, sucrose, carbon concentrations (5, 10, 20 and 25 g l-1, nitrogen sources (peptone, tryptone, yeast extract, beef extract and organic nitrogen mix, temperatures (25, 29, 33, 37, 41°C, pH (6, 6.5, 7 , 7.5 ,8, agitation rate (50, 100, 150, 200 rpm and amino acids (cysteine, cystine, tryptophanin batch cultivation ofLactobacillus plantarum NCIM 2912. Shake flask cultivation performed under optimum conditions like temperature 37°C, pH 7.0 and agitation rate of 150 rpm, resulted in enhanced sorbitol production. Comparative study of sorbitol production in solid state fermentation and submerged fermentation was also evaluated.Results and Conclusion: Batch cultivation under submerged conditions further performed in 7.5-l lab scale bioreactor (working volume 3.0-l under optimized conditions resulted in maximum cell biomass of 8.95±0.03 g g-1 and a sorbitol content of 9.78±0.04 g l-1 after 42.0 h of fermentation. Scale up study on bioreactor resulted in maximum sorbitol yield (Yp/x and productivity of 1.11 g g-1 and 0.50 g l-1 h under submerged fermentation, respectively.Conflict of interest: The authors declare no conflict of interest.
DETERMINATION OF ECONOMIC SIZES FOR RC CYLINDRICAL WATER STORAGE TANKS
Directory of Open Access Journals (Sweden)
Güneş KOZLUCA
2007-03-01
Full Text Available Water storage tanks are built in different shapes and sizes according to needs. Designs of water storage tanks with low costs are quite important for the national economy. Cylindrical and sphere tanks are the most economic types of tanks in terms of material cost. In this study several cylindrical tank designs are made. Then most economic tank radius – tank height ratio is searched by simply changing thickness, height and the radius of the tank considered. Storage capacity of these cylindrical tanks are all the same. All these reinforced tanks have cylindrical reinforced concrete walls fixed at the bottom and free top edge without roof. It is thought that tanks constructed with this optimal ratio will be beneficial.
Effect of SAR on human head modeling inside cylindrical enclosures.
Mary, T Anita Jones; Ravichandran, C S
2013-09-01
This study intends to discuss enclosed a realistic approach to determine and analyze the effects of radio frequency on human exposure inside a cylindrical enclosure. A scenario in which a mobile phone with inverted-F antenna (IFA) operating in the Global System for Mobile Communication (GSM) band (900 MHz) is used inside a cylindrical enclosure. Metallic enclosures are known to have resonance and reflection effects, thereby increasing electric field strength and hence resulting in a change of the human exposure to electromagnetic absorptions. So, this study examines and compares the levels of absorption in terms of specific absorption rate (SAR) values under various conditions. In this study, a human phantom with dielectric properties is designed and its interaction is studied with IFA inside fully enclosed cylindrical enclosures. The results show that SAR values are increased inside cylindrical enclosures compared with those in free space. The method of computation uses method of moments. Simulations are done in FEKO software.
Distributed shell control with a new multi-DOF photostrictive actuator design
Yue, H. H.; Sun, G. L.; Deng, Z. Q.; Tzou, H. S.
2010-08-01
With the photovoltaic effect and the converse piezoelectric effect, the lanthanum-modified lead zirconate titanate (PLZT) actuator can transform the narrow-band photonic energy to mechanical strain/stress—the photodeformation effect. This photodeformation process can be further used for non-contact precision actuation and control in various structural, biomedical and electromechanical systems. Although there are a number of design configurations of distributed actuators, e.g., segmentation and shaping, been investigated over the years, this study is to explore a new actuator configuration spatially bonded on the surface of shell structures to enhance the spatial modal controllability. A mathematical model of a new multiple degree-of-freedom (multi-DOF) photostrictive actuator configuration is presented first, followed by the photostrictive/shell coupling equations of a cylindrical shell structure laminated with the newly proposed multi-DOF distributed actuator. Distributed microscopic photostrictive actuation and its contributing components of a one-piece actuator and the multi-DOF actuator are evaluated in the modal domain. Effects of shell's curvature and actuator's size are also evaluated. Parametric analyses suggest that the new multi-DOF distributed actuator, indeed, provides better performance and control effect to shell actuation and control. This multi-DOF configuration can be further applied to actuation and control of various shell and non-shell structures.
Laminated Thin Shell Structures Subjected to Free Vibration in a Hygrothermal Environment
Gotsis, Pascal K.; Guptill, James D.
1994-01-01
Parametric studies were performed to assess the effects of various parameters on the free-vibration behavior (natural frequencies) of (+/- theta)(sub 2) angle-ply, fiber composite, thin shell structures in a hygrothermal environment. Knowledge of the natural frequencies of structures is important in considering their response to various kinds of excitation, especially when structures and force systems are complex and when excitations are not periodic. The three dimensional, finite element structural analysis computer code CSTEM was used in the Cray YMP computer environment. The fiber composite shell was assumed to be cylindrical and made from T300 graphite fibers embedded in an intermediate-modulus, high-strength matrix. The following parameters were investigated: the length and the laminate thickness of the shell, the fiber orientation, the fiber volume fraction, the temperature profile through the thickness of the laminate, and laminates with different ply thicknesses. The results indicate that the fiber orientation and the length of the laminated shell had significant effects on the natural frequencies. The fiber volume fraction, the laminate thickness, and the temperature profile through the shell thickness had weak effects on the natural frequencies. Finally, the laminates with different ply thicknesses had an insignificant influence on the behavior of the vibrated laminated shell. Also, a single through-the-thickness, eight-node, three dimensional composite finite element analysis appears to be sufficient for investigating the free-vibration behavior of thin, composite, angle-ply shell structures.
[Genetic algorithm for fermentation kinetics of submerged fermentation by Morchella].
Wang, Ying; Piao, Meizi; Sun, Yonghai
2008-08-01
Fermentation kinetics is important for optimizing control and up-scaling fermentation process. We studied submerged fermentation kinetics of Morchella. Applying the genetic Algorithm in the Matlab software platform, we compared suitability of the Monod and Logistic models, both are commonly used in process of fungal growth, to describe Morchella growth kinetics. Meanwhile, we evaluated parameters involved in the models for Morchella growth, EPS production and substrate consumption. The results indicated that Logistic model fit better with the experimental data. The average error of this model was 5.8%. This kinetics model can be useful for optimizing and up-scaling fungal fermentation process.
Liquid Film Diffusion on Reaction Rate in Submerged Biofilters
DEFF Research Database (Denmark)
Christiansen, Pia; Hollesen, Line; Harremoës, Poul
1995-01-01
Experiments were carried out in order to investigate the influence of liquid film diffusion on reaction rate in a submerged biofilter with denitrification and in order to compare with a theoretical study of the mass transfer coefficient. The experiments were carried out with varied flow, identified...... by the empty bed velocity of inflow and recirculation, respectively 1.3, 2.8, 5.6 and 10.9 m/h. The filter material consisted of 3 mm biostyren spheres. The results indicate that the influence of liquid film diffusion on reaction rate can be ignored....
Slag Metal Reactions during Submerged Arc Welding of Alloy Steels
Mitra, U.; Eagar, T. W.
1984-01-01
The transfer of Cr, Si, Mn, P, S, C, Ni, and Mo between the slag and the weld pool has been studied for submerged arc welds made with calcium silicate and manganese silicate fluxes. The results show a strong interaction between Cr and Si transfer but no interaction with Mn. The manganese silicate flux produces lower residual sulfur while the calcium silicate fluxes are more effective for removal of phosphorus. The effective oxygen reaction temperature lies between 1700 and 2000 °C for all elements studied. Evidence of Cr and Mn loss by metal vaporization is also presented.
Environmental and geometric optimisation of cylindrical drinking water storage tanks
Sanjuan Delmás, David
2015-01-01
The final publication is available at Springer via http://dx.doi.org/10.1007/s11367-015-0963-y Purpose: Urban water cycle construction processes are an important element to consider when assessing the sustainability of urban areas. The present study focuses on a structural and environmental analysis of cylindrical water tanks. The goal is to optimise cylindrical water tanks from both an environmental (environmental impacts due of life cycle assessment (LCA)) and a geometric perspective (bu...
Properties of interface phonon spectra in complicated cylindrical nanosystem
Directory of Open Access Journals (Sweden)
O.M.Voitsekhivska
2007-01-01
Full Text Available The spectra of two types of interface phonons (top and side optical are studied within the framework of dielectric continuum model for combined nanoheterosystems consisting of semiconductor cylindrical quantum dots inside the cylindrical quantum wire placed into dielectric or semiconductor medium. The dependencies of both types of interface phonon energies on the quasiwave numbers and geometric parameters of nanosystem are calculated and analysed.
Quantification of the geometrical parameters of non-cylindrical folds
Zulauf, G.; Zulauf, J.; Maul, H.
2017-07-01
The geometrical parameters of natural folds are used by structural geologists to estimate finite strain and rheological properties of deformed rocks. The relation between geometry and rheology is well understood in cases of cylindrical folds, but is still limited for non-cylindrical folds, although the latter are frequent in nature. The sparsity of quantitative geometrical data of non-cylindrical folds can be explained by the small number of 3D exposures and by the lack of robust methods to quantify their geometrical parameters in 3D space. We present a new workflow, which can be used to quantify geometrical parameters of non-cylindrical folds. 3D fold geometry is described using fold wavelength, λ, arc-length, L, and amplitude, A. As most natural folds do not show ideal shapes, but are affected by various types of discontinuities, the new procedure is not fully automatic, but requires the manual selection of measuring profiles along which the geometrical parameters are constrained. The new workflow is tested using natural and experimentally produced non-cylindrical folds. The geometric parameters obtained can be used to improve our understanding of fold kinematics and fold mechanics and should assist the quantitative analysis of non-cylindrical folds present in gneiss and salt domes and in rocks containing reservoirs of hydrocarbons and minerals deposits.
Theory and modeling of cylindrical thermo-acoustic transduction
Energy Technology Data Exchange (ETDEWEB)
Tong, Lihong, E-mail: lhtong@ecjtu.edu.cn [School of Civil Engineering and Architecture, East China Jiaotong University, Nanchang, Jiangxi (China); Lim, C.W. [Department of Architecture and Civil Engineering, City University of Hong Kong, Kowloon, Hong Kong SAR (China); Zhao, Xiushao; Geng, Daxing [School of Civil Engineering and Architecture, East China Jiaotong University, Nanchang, Jiangxi (China)
2016-06-03
Models both for solid and thinfilm-solid cylindrical thermo-acoustic transductions are proposed and the corresponding acoustic pressure solutions are obtained. The acoustic pressure for an individual carbon nanotube (CNT) as a function of input power is investigated analytically and it is verified by comparing with the published experimental data. Further numerical analysis on the acoustic pressure response and characteristics for varying input frequency and distance are also examined both for solid and thinfilm-solid cylindrical thermo-acoustic transductions. Through detailed theoretical and numerical studies on the acoustic pressure solution for thinfilm-solid cylindrical transduction, it is concluded that a solid with smaller thermal conductivity favors to improve the acoustic performance. In general, the proposed models are applicable to a variety of cylindrical thermo-acoustic devices performing in different gaseous media. - Highlights: • Theory and modeling both for solid and thinfilm-solid cylindrical thermo-acoustic transductions are proposed. • The modeling is verified by comparing with the published experimental data. • Acoustic response characteristics of cylindrical thermo-acoustic transductions are predicted by the proposed model.
Palazzi, Paolo
2007-01-01
A stability analysis of the mass spectrum indicates that hadrons, like atoms and nuclei, are shell-structured. The mesonic shells mass series, combined with the results of a mass quantization analysis, reveals striking similarities with the nuclear shells. In addition, the mesonic mass patterns suggest solid-phase partonic bound states on an fcc lattice, compatible with a model by A. O. Barut with stable leptons as constituents, bound by magnetism. Baryonic shells grow with a lower density, and only start at shell 3 with the nucleon.
Cathodic disbonding of organic coatings on submerged steel
Energy Technology Data Exchange (ETDEWEB)
Knudsen, Ole oeystein
1998-12-31
In offshore oil production, submerged steel structures are commonly protected by an organic coating in combination with cathodic protection. The main advantage is that the coating decreases the current demand for cathodic protection. But the coating degrades with time. This thesis studies one of the most important mechanisms for coating degradation in seawater, cathodic disbonding. Seven commercial coatings and two model coatings with various pigmentations have been studied. Parameter studies, microscopy and studies of free films were used in the mechanism investigations. Exposure to simulated North Sea conditions was used in the performance studies. The effect of aluminium and glass barrier pigments on cathodic disbonding was investigated. The mechanism for the effect of the aluminium pigments on cathodic disbonding was also investigated. The transport of charge and oxygen to the steel/coating interface during cathodic disbonding was studied for two epoxy coatings. Cathodic disbonding, blistering and current demand for cathodic protection was measured for nine commercial coatings for submerged steel structures, using the ASTM-G8 standard test and a long term test under simulated North Sea conditions. The relevance of the ASTM-G8 test as a prequalification test was evaluated. 171 refs., 40 figs., 6 tabs.
Period Doubling in Bubbling from a Submerged Nozzle
Dennis, Jordan; Grace, Laura; Lehman, Susan
The timing of bubbles rising from a nozzle submerged in a viscous solution was measured to examine the period-doubling route to chaos in this system. A narrow nozzle was submerged in a mixture of water and glycerin, and nitrogen was supplied to the nozzle at a varying flow rate. The bubbles were detected using a laser and photodiode system; when the bubbles rise through the laser beam, they scatter the light so that the signal at the photodiode decreases. The period between bubbles as well as the duration of each bubble (a function of bubble size and bubble velocity) was determined, and examined as the nitrogen flow rate increased, for solutions with five different concentrations of glycerin. Bubbles were also recorded visually using a high-speed camera. Within the flow rates tested, we observed a bifurcation of the period to period-2 behavior for all solutions tested, and a further bifurcation to period-4 for all solutions except pure glycerin. The solution viscosity affected both the onset of the bifurcation and the precise bubble behavior during the bifurcation. Unusually, a short period/long period pair of bubbles recurring at a regular interval was sometimes observed in the low flow regime which is typically period-1, an observation which requires further investigation. Research supported by NSF DMR 1560093.
Magnetic imaging of a submerged Roman harbour, Caesarea Maritima, Israel
Boyce, J. I.; Reinhardt, E. G.; Raban, A.; Pozza, M. R.
2003-04-01
The harbour built by King Herod's engineers at Caesarea represented a major advance in Roman harbour construction that incorporated the use of large (390 m^3), form-filled hydraulic concrete blocks to build an extensive foundation for the harbour moles and breakwater barriers. Marine geophysical surveys were recently conducted across the submerged harbour in an attempt to map the configuration of the buried concrete foundation. A total of 107 line km of high-resolution marine magnetic surveys (nominal 15 m line separations) and bathymetry data were acquired over a 1 km^2 area of the submerged harbour using an Overhauser marine magnetometer, integrated DGPS and single-beam (200 KHz) echosounder. The feasibility of magnetic detection of the concrete was established before the survey by magnetic susceptibility testing of concrete core samples. All concrete samples contained appreciable amounts of fe-oxide-rich volcanic ash ('pozzolana') and showed uniformly high susceptibility values (k > 10^-^4 cgs) when compared to harbour bottom sediments and building stones (k construction of the harbour moles and quays.
THE INFLUENCE OF SUBMERGED MACROPHYTES ON SEDIMENTARY DIATOM ASSEMBLAGES(1).
Vermaire, Jesse C; Prairie, Yves T; Gregory-Eaves, Irene
2011-12-01
Submerged macrophytes are a central component of lake ecosystems; however, little is known regarding their long-term response to environmental change. We have examined the potential of diatoms as indicators of past macrophyte biomass. We first sampled periphyton to determine whether habitat was a predictor of diatom assemblage. We then sampled 41 lakes in Quebec, Canada, to evaluate whether whole-lake submerged macrophyte biomass (BiomEpiV) influenced surface sediment diatom assemblages. A multivariate regression tree (MRT) was used to construct a semiquantitative model to reconstruct past macrophyte biomass. We determined that periphytic diatom assemblages on macrophytes were significantly different from those on wood and rocks (ANOSIM R = 0.63, P macrophyte, nutrient-limited lakes (BiomEpiV ≥525 μg · L(-1) ; total phosphorus [TP] macrophyte, nutrient-limited lakes (BiomEpiV eutrophic lakes (TP ≥35 μg · L(-1) ; six lakes). A semiquantitative model correctly predicted the MRT group of the lake 71% of the time (P macrophytes have a significant influence on diatom community structure and that sedimentary diatom assemblages can be used to infer past macrophyte abundance. © 2011 Phycological Society of America.
Akman, M.; Bhikharie, A.V.; McLean, E.H.; Boonman, A.; Visser, E.J.W.; Schranz, M.E.; van Tienderen, P.H.
2012-01-01
Background and Aims Differential responses of closely related species to submergence can provide insight into the evolution and mechanisms of submergence tolerance. Several traits of two wetland species from habitats with contrasting flooding regimes, Rorippa amphibia and Rorippa sylvestris, as well
Xing W.; Shi Q.; Liu H.; Liu G.
2016-01-01
Growth rate hypothesis (GRH) and stoichiometric homeostasis of photoautotrophs have always been questioned. However, little is known about GRH and stoichiometric homeostasis of aquatic plants, especially submerged macrophytes. Therefore, we aim to test the GRH and explore stoichiometric homeostasis of four freshwater submerged macrophytes under eutrophication stress. At the single species level and the multi-species level, N:P ratios ...
HST/ACS observations of shell galaxies: inner shells, shell colours and dust
Sikkema, G.; Carter, D.; Peletier, R. F.; Balcells, M.; Del Burgo, C.; Valentijn, E. A.
2007-06-01
Context: Shells in Elliptical Galaxies are faint, sharp-edged features, believed to provide evidence for a merger event. Accurate photometry at high spatial resolution is needed to learn on presence of inner shells, population properties of shells, and dust in shell galaxies. Aims: Learn more about the origin of shells and dust in early type galaxies. Methods: V-I colours of shells and underlying galaxies are derived, using HST Advanced Camera for Surveys (ACS) data. A galaxy model is made locally in wedges and subtracted to determine shell profiles and colours. We applied Voronoi binning to our data to get smoothed colour maps of the galaxies. Comparison with N-body simulations from the literature gives more insight to the origin of the shell features. Shell positions and dust characteristics are inferred from model galaxy subtracted images. Results: The ACS images reveal shells well within the effective radius in some galaxies (at 0.24 re = 1.7 kpc in the case of NGC 5982). In some cases, strong nuclear dust patches prevent detection of inner shells. Most shells have colours which are similar to the underlying galaxy. Some inner shells are redder than the galaxy. All six shell galaxies show out of dynamical equilibrium dust features, like lanes or patches, in their central regions. Our detection rate for dust in the shell ellipticals is greater than that found from HST archive data for a sample of normal early-type galaxies, at the 95% confidence level. Conclusions: The merger model describes better the shell distributions and morphologies than the interaction model. Red shell colours are most likely due to the presence of dust and/or older stellar populations. The high prevalence and out of dynamical equilibrium morphologies of the central dust features point towards external influences being responsible for visible dust features in early type shell galaxies. Inner shells are able to manifest themselves in relatively old shell systems. Based on observations made
Digital Repository Service at National Institute of Oceanography (India)
Gaur, A.S.; Sundaresh
. It is difficult to assign a particular reason for the submergence of the temple in discussion, however minor sea level rise and seismic activity might have played a vital role in submergence of the temple complex....
Digital Repository Service at National Institute of Oceanography (India)
Rao, K.M.; Murthy, K.S.R.; Reddy, N.P.C.; Subrahmanyam, A.S.; Lakshminarayana, S.; Rao, M.M.M.; Sarma, K.V.L.N.S.; Premkumar, M.K.; Sree, A.; Bapuji, M.
. (e - mail: kmrao@kadali.nio.org) RESEARCH COMMUNICATIONS CURRENT SCIENCE, VOL. 81, NO. 7, 10 OCTOBER 2001 829 mic profiling to locate the submerged roc k outcrops. Though the submerged topographic features were r e por - ted by some...
EAARL-B Submerged TopographyâSaint Croix, U.S. Virgin Islands, 2014
U.S. Geological Survey, Department of the Interior — A submerged topography Digital Elevation Model (DEM) mosaic for a portion of the submerged environs of Saint Croix, U.S. Virgin Islands, was produced from remotely...
THE STUDY ON THE DURABILITY OF SUBMERGED STRUCTURE DISPLACEMENT DUE TO CONCRETE FAILURE
Directory of Open Access Journals (Sweden)
M. Mohd
2016-09-01
Full Text Available Concrete structures that exposed to marine environments are subjected to multiple deterioration mechanisms. An overview of the existing technology for submerged concrete, pressure resistant, concrete structures which related such as cracks, debonds, and delamination are discussed. Basic knowledge related to drowning durability such as submerged concrete structures in the maritime environment are the durability of a concrete and the ability to resist to weathering, chemical attack, abrasion or other deterioration processes. The measuring techniques and instrumentation for geometrical monitoring of submerged structural displacements have traditionally been categorized into two groups according to the two main groups, namely as geodetic surveying and geotechnical structural measurements of local displacements. This paper aims to study the durability of submerged concrete displacement and harmful effects of submerged concrete structures.
[Effects of light on submerged macrophytes in eutrophic water: research progress].
Li-Sha, Zou; Ze-Yu, Nie; Xiao-Yan, Yao; Ji-Yan, Shi
2013-07-01
The restoration of submerged macrophytes is the key to remediate eutrophic water and maintain the health of aquatic ecosystem, while light is the main limiting factor. This paper summarized the factors affecting the light extinction in water and the mechanisms of light intensity affecting the physiology of submerged macrophytes, with the focuses on the metabolic mechanisms of carbon, nitrogen, and phosphorus, the responses of antioxidant enzyme system, and the feedbacks of pigment composition and concentration in the common submerged macrophytes under low light stress. Several engineering techniques applied in the ecological restoration of submerged macrophytes were presented, and the framework of the restoration of submerged macrophytes in eutrophic water was proposed. Some problems in current research and several suggestions on future research were addressed, which could help the related research and engineering practices.
Leaf gas films contribute to rice (Oryza sativa) submergence tolerance during saline floods
DEFF Research Database (Denmark)
Herzog, Max; Konnerup, Dennis; Pedersen, Ole
2018-01-01
Floods and salinization of agricultural land adversely impact global rice production. We investigated whether gas films on leaves of submerged rice delay salt entry during saline submergence. Two-week-old plants with leaf gas films (+GF) or with gas films experimentally removed (-GF) were submerg...
Experiments on annular liquid jet instability and on the formation of liquid shells
Kendall, J. M.
1986-01-01
An annular jet flow of liquid surrounding a flow of gas at its core is extremely unstable. Experiments are described in which such a flow is generated by an annular nozzle operated at fairly specific conditions. It is shown that periodic, axisymmetric oscillations arise spontaneously within the cylindrical sheet emerging from the nozzle and grow with such rapidity along the axial dimension that a sealing-off and encapsulation of the core gas occurs within a few jet diameters. This is closely followed by a pinchoff of the liquid between adjacent bubbles. The liquid shells set free thereby assume spherically symmetric form under capillary forces, and each contains a precisely uniform measure of gas and of liquid on account of the extremely high frequency-stability of the process. Description is given of the fluid dynamic processes by which the shells are formed, and mention is made of exploiting the instability for the production of rigid shells for technological applications.
Nemeth, Michael P.
2014-01-01
Nonlinear and bifurcation buckling equations for elastic, stiffened, geometrically perfect, right-circular cylindrical, anisotropic shells subjected to combined loads are presented that are based on Sanders' shell theory. Based on these equations, a three-parameter approximate Rayleigh-Ritz solution and a classical solution to the buckling problem are presented for cylinders with simply supported edges. Extensive comparisons of results obtained from these solutions with published results are also presented for a wide range of cylinder constructions. These comparisons include laminated-composite cylinders with a wide variety of shell-wall orthotropies and anisotropies. Numerous results are also given that show the discrepancies between the results obtained by using Donnell's equations and variants of Sanders' equations. For some cases, nondimensional parameters are identified and "master" curves are presented that facilitate the concise representation of results.
Multi-Shell Shell Model for Heavy Nuclei
Sun, Yang; Wu, Cheng-Li
2003-01-01
Performing a shell model calculation for heavy nuclei has been a long-standing problem in nuclear physics. Here we propose one possible solution. The central idea of this proposal is to take the advantages of two existing models, the Projected Shell Model (PSM) and the Fermion Dynamical Symmetry Model (FDSM), to construct a multi-shell shell model. The PSM is an efficient method of coupling quasi-particle excitations to the high-spin rotational motion, whereas the FDSM contains a successful t...
Novel spherical hohlraum with cylindrical laser entrance holes and shields
Energy Technology Data Exchange (ETDEWEB)
Lan, Ke [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China); Center for Applied Physics and Technology, Peking University, Beijing 100871 (China); Zheng, Wudi [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China)
2014-09-15
Our recent works [K. Lan et al., Phys. Plasmas 21, 010704 (2014); K. Lan et al., Phys. Plasmas 21, 052704 (2014)] have shown that the octahedral spherical hohlraums are superior to the cylindrical hohlraums in both higher symmetry during the capsule implosion and lower backscatter without supplementary technology. However, both the coupling efficiency from the drive laser energy to the capsule and the capsule symmetry decrease remarkably when larger laser entrance holes (LEHs) are used. In addition, the laser beams injected at angles > 45° transport close to the hohlraum wall, thus the wall blowoff causes the LEH to close faster and results in strong laser plasma interactions inside the spherical hohlraums. In this letter, we propose a novel octahedral hohlraum with LEH shields and cylindrical LEHs to alleviate these problems. From our theoretical study, with the LEH shields, the laser coupling efficiency is significantly increased and the capsule symmetry is remarkably improved in the spherical hohlraums. The cylindrical LEHs take advantage of the cylindrical hohlraum near the LEH and mitigate the influence of the blowoff on laser transport inside a spherical hohlraum. The cylindrical LEHs can also be applied to the rugby and elliptical hohlraums.
Laser confocal cylindrical radius measurement method and its system.
Xiao, Yang; Qiu, Lirong; Zhao, Weiqian
2017-08-10
This paper proposes a laser confocal cylindrical radius of the curvature measurement (CCRM) method. The CCRM method precisely identifies the positions of the vertex and curvature center of the test cylindrical surface by using the property so that the maximum point of the laser confocal axial intensity curve precisely corresponds to the focus of the laser confocal measurement system, and the accurate distance of these two positions is obtained by the distance measuring instrument, thus achieving the precise measurement of the cylindrical radius. The quadratic fitting method is used to further improve the measurement accuracy. Compared with existing measurement methods, the CCRM method has high measurement precision, simple structure, and strong environmental interference capability, and it is more suitable for engineering applications. Based on the CCRM, the CCRM system is established, and theoretical analysis and preliminary experiments indicate that the relative uncertainty of cylindrical radius measurement is better than 0.045%. Therefore, the CCRM provides an effective approach for the high-precision measurement of cylindrical radius.
The decrease of cylindrical pempek quality during boiling
Karneta, R.; Gultom, N. F.
2017-09-01
The research objective was to study the effects of temperature and formulation on quality of pempek lenjer during boiling. Treatments in this study were four levels of pempek formulation and five levels of temperature. Data was processed by using analysis of variance (Anova). If test results showed that samples were significantly different or highly significantly different, then further test was conducted by using Honestly Significant Different. The results showed that chemical analysis showed that fish dominant formula of cylindrical pempek had higher water content, protein content, lipid content and ash content than that of tapioca starch dominant formula, but it had lower carbohydrate content and fibre content than that of tapioca starch dominant formula.The higher the temperature at center point of cylindrical pempek, the lower the chemical quality of cylindrical pempek. The effect of formula on physical quality of cylindrical pempek showed that tapioca starch dominant formula had more rubbery texture, more neutral pH and brighter color than that of fish dominant formula.The temperature change had no significant effect on texture and pH of cylindrical pempek, but it had significant effect on lightness, intensity and chromatic color especially after exceeding optimum time of boiling.
Wrinkling of Pressurized Elastic Shells
Vella, Dominic; Ajdari, Amin; Vaziri, Ashkan; Boudaoud, Arezki
2011-10-01
We study the formation of localized structures formed by the point loading of an internally pressurized elastic shell. While unpressurized shells (such as a ping-pong ball) buckle into polygonal structures, we show that pressurized shells are subject to a wrinkling instability. We study wrinkling in depth, presenting scaling laws for the critical indentation at which wrinkling occurs and the number of wrinkles formed in terms of the internal pressurization and material properties of the shell. These results are validated by numerical simulations. We show that the evolution of the wrinkle length with increasing indentation can be understood for highly pressurized shells from membrane theory. These results suggest that the position and number of wrinkles may be used in combination to give simple methods for the estimation of the mechanical properties of highly pressurized shells.
Wrinkling of Pressurized Elastic Shells
Vella, Dominic
2011-10-01
We study the formation of localized structures formed by the point loading of an internally pressurized elastic shell. While unpressurized shells (such as a ping-pong ball) buckle into polygonal structures, we show that pressurized shells are subject to a wrinkling instability. We study wrinkling in depth, presenting scaling laws for the critical indentation at which wrinkling occurs and the number of wrinkles formed in terms of the internal pressurization and material properties of the shell. These results are validated by numerical simulations. We show that the evolution of the wrinkle length with increasing indentation can be understood for highly pressurized shells from membrane theory. These results suggest that the position and number of wrinkles may be used in combination to give simple methods for the estimation of the mechanical properties of highly pressurized shells. © 2011 American Physical Society.
Free Vibration of Fiber Composite Thin Shells in a Hot Environment
Gotsis, Pascal K.; Guptill, James D.
1995-01-01
Results are presented of parametric studies to assess the effects of various parameters on the free vibration behavior (natural frequencies) of (plus or minus theta)2, angle-ply fiber composite thin shells in a hot environment. These results were obtained by using a three-dimensional finite element structural analysis computer code. The fiber composite shell is assumed to be cylindrical and made from T-300 graphite fibers embedded in an intermediate-modulus high-strength matrix (IMHS). The residual stresses induced into the laminated structure during curing are taken into account. The following parameters are investigated: the length and the thickness of the shell, the fiber orientations, the fiber volume fraction, the temperature profile through the thickness of the laminate and the different ply thicknesses. Results obtained indicate that: the fiber orientations and the length of the laminated shell had significant effect on the natural frequencies. The fiber volume fraction, the laminate thickness and the temperature profile through the shell thickness had a weak effect on the natural frequencies. Finally, the laminates with different ply thicknesses had insignificant influence on the behavior of the vibrated laminated shell.
Critical Assessment of Temperature Distribution in Submerged Arc Welding Process
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Vineet Negi
2013-01-01
Full Text Available Temperature distribution during any welding process holds the key for understanding and predicting several important welding attributes like heat affected zone, microstructure of the weld, residual stress, and distortion during welding. The accuracy of the analytical approaches for modeling temperature distribution during welding has been constrained by oversimplified assumptions regarding boundary conditions and material properties. In this paper, an attempt has been made to model the temperature distribution during submerged arc welding process using finite element modeling technique implemented in ANSYS v12. In the present analysis, heat source is assumed to be double-ellipsoidal with Gaussian volumetric heat generation. Furthermore, variation of material properties with temperature and both convective and radiant heat loss boundary condition have been considered. The predicted temperature distribution is then validated against the experimental results obtained by thermal imaging of the welded plate, and they are found to be in a good agreement.
Arc characteristics of submerged arc welding with stainless steel wire
Li, Ke; Wu, Zhi-sheng; Liu, Cui-rong; Chen, Feng-hua
2014-08-01
The arc characteristics of submerged arc welding (SAW) with stainless steel wire were studied by using Analysator Hannover (AH). The tests were carried out under the same preset arc voltage combined with different welding currents. By comparing the probability density distribution (PDD) curves of arc voltage and welding current, the changes were analyzed, the metal transfer mode in SAW was deduced, and the characteristics of a stable arc were summarized. The analysis results show that, with an increase of welding parameters, the short-circuiting peak in the PDD curves of arc voltage decreases gradually until it disappears, and the dominant metal transfer mode changes from flux-wall guided transfer to projected transfer and then to streaming transfer. Moreover, when the PDD curves of arc voltage are both unimodal and generally symmetrical, the greater the peak probability and the smaller the peak span, the more stable the arc becomes.
Numerical study on tsunami hazard mitigation using a submerged breakwater.
Ha, Taemin; Yoo, Jeseon; Han, Sejong; Cho, Yong-Sik
2014-01-01
Most coastal structures have been built in surf zones to protect coastal areas. In general, the transformation of waves in the surf zone is quite complicated and numerous hazards to coastal communities may be associated with such phenomena. Therefore, the behavior of waves in the surf zone should be carefully analyzed and predicted. Furthermore, an accurate analysis of deformed waves around coastal structures is directly related to the construction of economically sound and safe coastal structures because wave height plays an important role in determining the weight and shape of a levee body or armoring material. In this study, a numerical model using a large eddy simulation is employed to predict the runup heights of nonlinear waves that passed a submerged structure in the surf zone. Reduced runup heights are also predicted, and their characteristics in terms of wave reflection, transmission, and dissipation coefficients are investigated.
Numerical Study on Tsunami Hazard Mitigation Using a Submerged Breakwater
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Taemin Ha
2014-01-01
Full Text Available Most coastal structures have been built in surf zones to protect coastal areas. In general, the transformation of waves in the surf zone is quite complicated and numerous hazards to coastal communities may be associated with such phenomena. Therefore, the behavior of waves in the surf zone should be carefully analyzed and predicted. Furthermore, an accurate analysis of deformed waves around coastal structures is directly related to the construction of economically sound and safe coastal structures because wave height plays an important role in determining the weight and shape of a levee body or armoring material. In this study, a numerical model using a large eddy simulation is employed to predict the runup heights of nonlinear waves that passed a submerged structure in the surf zone. Reduced runup heights are also predicted, and their characteristics in terms of wave reflection, transmission, and dissipation coefficients are investigated.
Phytoremediation of arsenic in submerged soil by wetland plants.
Jomjun, Nateewattana; Siripen, Trichaiyaporn; Maliwan, Saeouy; Jintapat, Nateewattana; Prasak, Thavornyutikarn; Somporn, Choonluchanon; Petch, Pengchai
2011-01-01
Wetland aquatic plants including Canna glauca L., Colocasia esculenta L. Schott, Cyperus papyrus L. and Typha angustifolia L. were used in the phytoremediation of submerged soil polluted by arsenic (As). Cyperus papyrus L. was noticed as the largest biomass producer which has arsenic accumulation capacity of 130-172 mg As/kg plant. In terms of arsenic removal rate, however, Colocasia esculenta L. was recognized as the largest and fastest arsenic remover in this study. Its arsenic removal rate was 68 mg As/m2/day while those rates of Canna glauca L., Cyperus papyrus L. and Typha angustifolia L. were 61 mg As/m2/day, 56 mg As/m2/day, and 56 mg As/m2/day, respectively. Although the 4 aquatic plants were inferior in arsenic accumulation, their high arsenic removal rates were observed. Phytostabilization should be probable for the application of these plants.
Minimizing downstream scour due to submerged hydraulic jump using corrugated
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Hossam Mohamed Ali
2014-12-01
Full Text Available Local scour downstream of hydraulic structures due to hydraulic jump is considered one of the tedious and complicated problems facing their stability. Throughout this paper, an experimental study was conducted to study the effect of using different spaced corrugated aprons on the downstream local scour due to submerged jump. Sixty runs were carried out in a horizontal rectangular flume to determine the optimal corrugation wavelength which minimizing the scour. A case of flat apron included to estimate the influence of corrugated aprons on scour holes dimensions. Two types of non-cohesive soil were used. Experiments were performed for a range of Froude numbers between 1.68 and 9.29. The results showed that using spaced triangular corrugated aprons minimize the scour depth and length of fine sand by average percentage of 63.4% and 30.2%, respectively and for coarse sand by 44.2% and 20.6% in comparing with classical jump.
Microbial production of four biodegradable siderophores under submerged fermentation.
Fazary, Ahmed E; Al-Shihri, Ayed S; Alfaifi, Mohammad Y; Saleh, Kamel A; Alshehri, Mohammed A; Elbehairi, Serag Eldin I; Ju, Yi-Hsu
2016-07-01
Four siderophore analogues were isolated and purified from Escherichia coli, Bacillus spp. ST13, and Streptomyces pilosus microorganisms under some specific submerged fermentation conditions. In order to evaluate the highest production of this siderophore analogues through the growth, a rapid spectrophotometric screening semi-quantitative method was used, in which interestingly the analogues were isolated in its own form not its iron chelate. After chromatographic separation, the chemical structures of the isolated and purified siderophores were illustrated using detailed spectroscopic techniques. The biodegradation studies were done on that four novel isolated and purified siderophores following OECD protocols. In addition, the bioactivities of these siderophores and their iron complexes were examined and evaluated. Copyright © 2016 Elsevier B.V. All rights reserved.
Development of Submerged Entry Nozzles that Resist Clogging
Energy Technology Data Exchange (ETDEWEB)
Dr. Jeffrey D. Smith; Kent D. Peasle
2002-10-14
Accretion formation and the associated clogging of SENs is a major problem for the steel industry leading to decreased strand speed, premature changing of SENs or strand termination and the associated reductions in productivity, consistency, and steel quality. A program to evaluate potentially clog resistance materials was initiated at the University of Missouri-Rolla. The main objective of the research effort was to identify combinations of steelmaking and refractory practices that would yield improved accretion resistance for tundish nozzles and submerged entry nozzles. A number of tasks were identified during the initial kick-off meeting and each was completed with two exceptions, the thermal shock validation and the industrial trials. Not completing these two tasks related to not having access to industrial scale production facilities. Though much of the results and information generated in the project is of proprietary nature.
Slag-metal equilibrium during submerged arc welding
Chai, C. S.; Eagar, T. W.
1981-09-01
A thermodynamic model of the equilibria existing between the slag and the weld metal during submerged arc welding is presented. As formulated, the model applies only to fused neutral fluxes containing less than 20 pct CaF2, however some results indicate that the model may be useful in more general cases as well. The model is shown to be capable of predicting the gain or loss of both Mn and Si over a wide range of baseplate, electrode and flux compositions. At large deviations from the predicted equilibrium, the experimental results indicate considerable variability in the amount of Mn or Si transferred between the slag and metal phases, while closer to the calculated equilibrium, the extent of metal transfer becomes more predictable. The variability in metal transfer rate at large deviations from equilibrium may be explained by variations between the bulk and the surface concentrations of Mn and Si in both metal and slag phases.
Endodontic Treatment in Submerged Roots: A Case Report
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Hemalatha Pameshwar Hiremath
2010-06-01
Full Text Available Alveolar ridge resorption has long been considered an unavoidable consequence of tooth extraction. While the extent and pattern of resorption is variable among individuals, there is a progressive loss of ridge contour as a result of physiologic bone remodeling. Even today, with best modalities of tooth preservation, there is a group of elderly individuals who do not benefit from modern preventive practices and who now present a dilemma in terms of maintaining the masticatory apparatus necessary for nutrition. Even with excellent dental care, such patients experience abrasion of the natural tooth crowns with age, and embedded roots are left within the alveolar bone. According to old concepts of dental care, extraction of these roots would have been recommended, but today’s goal of excellence in endodontics dictates otherwise. We report a case in which vital and non-vital root submergence was carried out to prevent alveolar ridge reduction.
Plate shell structures of glass
DEFF Research Database (Denmark)
Bagger, Anne
to their curved shape. A plate shell structure maintains a high stiffness-to-weight ratio, while facilitating the use of plane structural elements. The study focuses on using laminated glass panes for the load bearing facets. Various methods of generating a plate shell geometry are suggested. Together with Ghent......, such as facet size, imperfections, and connection characteristics. The critical load is compared to that of a similar, but smoothly curved, shell structure. Based on the investigations throughout the study, a set of guidelines for the structural design of plate shells of glass is proposed....
Experimental and numerical analysis of cylindrical straw drying
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Goryl Wojciech
2017-01-01
Full Text Available The paper presents experimental and numerical results of the heat and mass transfer in a cylindrical bale of straw. The experimental measurements were made in a specialized stand of straw driers. Flue gasses, comes from straw combustion in the biomass boiler, are used as a drying medium. There were made measurements of humidity and temperature inside the cylindrical straw bale during the drying process. The results were used to prepare the drying rate curve. Moreover, data were used to validate the numerical model of straw drying. The numerical model was performed to depict the heat and mass transfer inside the straw bale. Furthermore, the model was used to optimize the drying process. The paper presents result of experimental and numerical drying rates of cylindrical straw bale and heat and mass transfer in its interior. As a result of the work numerical model was obtained. It satisfactorily describes the mechanisms inside the drying straw bale.
Experiments of cylindrical isentropic compression by ultrahigh magnetic field
Gu, Zhuowei; Zhou, Zhongyu; Zhang, Chunbo; Tang, Xiaosong; Tong, Yanjin; Zhao, Jianheng; Sun, Chengwei
2015-09-01
The high Explosive Magnetic Flux Implosion Compression Generator (EMFICG) is a kind of unique high energy density dynamic technique with characters like ultrahigh pressure and low temperature rising and could be suitable as a tool of cylindrical isentropic compression. The Institute of Fluid Physics, Chinese Academy of Engineering Physics (IFP, CAEP) have developed EMFICG technique and realized cylindrical isentropic compression. In the experiments, a seed magnetic field of 5-6 Tesla were built first and compressed by a stainless steel liner which is driven by high explosive. The inner free surface velocity of sample was measured by PDV. The isentropic compression of a copper sample was verified and the isentropic pressure is over 100 GPa. The cylindrical isentropic compression process has been numerical simulated by 1D MHD code and the simulation results were compared with the experiments. Compared with the transitional X-ray flash radiograph measurement, this method will probably promote the data accuracy.
Experiments of cylindrical isentropic compression by ultrahigh magnetic field
Directory of Open Access Journals (Sweden)
Gu Zhuowei
2015-01-01
Full Text Available The high Explosive Magnetic Flux Implosion Compression Generator (EMFICG is a kind of unique high energy density dynamic technique with characters like ultrahigh pressure and low temperature rising and could be suitable as a tool of cylindrical isentropic compression. The Institute of Fluid Physics, Chinese Academy of Engineering Physics (IFP, CAEP have developed EMFICG technique and realized cylindrical isentropic compression. In the experiments, a seed magnetic field of 5–6 Tesla were built first and compressed by a stainless steel liner which is driven by high explosive. The inner free surface velocity of sample was measured by PDV. The isentropic compression of a copper sample was verified and the isentropic pressure is over 100 GPa. The cylindrical isentropic compression process has been numerical simulated by 1D MHD code and the simulation results were compared with the experiments. Compared with the transitional X-ray flash radiograph measurement, this method will probably promote the data accuracy.
Magnetostatic interactions in cylindrical nanostructures with non-uniform magnetization
Energy Technology Data Exchange (ETDEWEB)
Suarez, O.J. [Departamento de Fisica, Universidad Tecnica Federico Santa Maria, Casilla 110-V, Valparaiso (Chile); Perez, L.M. [Departamento de Fisica y Matematica Aplicada, Universidad de Navarra, 31080 Pamplona (Spain); Laroze, D., E-mail: david.laroze@gmail.com [Max Planck Institute for Polymer Research, D 55021 Mainz (Germany); Instituto de Alta Investigacion, Universidad de Tarapaca, Casilla 7D, Arica (Chile); Altbir, D. [Departamento de Fisica and Center for the Development of Nanoscience and Nanotechnology, Universidad de Santiago de Chile, Av. Ecuador 3493, Santiago (Chile)
2012-05-15
Cylindrical magnetic nanostructures, like nanowires or nanotubes, should be used for the new generation of magnetic devices. Therefore, the investigation of inter-element interaction is an intense area of research. In this paper we investigated cylindrical nanostructures with non-uniform magnetization field. We focus on particles with a periodic magnetization function and using Fourier series we reduced the problem to a single integral expression. Analytical expressions for both, the self and the interaction magnetostatic energy, are given. These expressions are used to analyze multisegmented tubes, as a function of the number of segments and the distance between particles. - Highlights: Black-Right-Pointing-Pointer Magnetic cylindrical nanoparticles like nanowires or nanotubes. Black-Right-Pointing-Pointer Magnetostatic interaction between particles. Black-Right-Pointing-Pointer Non-uniform magnetization states.
Determination of the Boltzmann Constant Using the Differential - Cylindrical Procedure
Feng, X J; Lin, H; Gillis, K A; Moldover, M R
2015-01-01
We report in this paper the progresses on the determination of the Boltzmann constant using the acoustic gas thermometer (AGT) of fixed-length cylindrical cavities. First, we present the comparison of the molar masses of pure argon gases through comparing speeds of sound of gases. The procedure is independent from the methodology by Gas Chromatography-Mass Spectrometry (GC-MS). The experimental results show good agreement between both methods. The comparison offers an independent inspection of the analytical results by GC-MS. Second, we present the principle of the novel differential-cylindrical procedure based on the AGT of two fixed-length cavities. The deletion mechanism for some major perturbations is analyzed for the new procedure. The experimental results of the differential-cylindrical procedure demonstrate some major improvements on the first, second acoustic and third virial coefficients, and the excess half-widths. The three acoustic virial coefficients agree well with the stated-of-the-art experime...
Komar fluxes of circularly polarized light beams and cylindrical metrics
Lynden-Bell, D.; Bičák, J.
2017-11-01
The mass per unit length of a cylindrical system can be found from its external metric as can its angular momentum. Can the fluxes of energy, momentum, and angular momentum along the cylinder also be so found? We derive the metric of a beam of circularly polarized electromagnetic radiation from the Einstein-Maxwell equations. We show how the uniform plane wave solutions miss the angular momentum carried by the wave. We study the energy, momentum, angular momentum, and their fluxes along the cylinder both for this beam and in general. The three Killing vectors of any stationary cylindrical system give three Komar flux vectors which in turn give six conserved fluxes. We elucidate Komar's mysterious factor 2 by evaluating Komar integrals for systems that have no trace to their stress tensors. The Tolman-Komar formula gives twice the energy for such systems which also have twice the gravity. For other cylindrical systems their formula gives correct results.
Automated shell theory for rotating structures (ASTROS)
Foster, B. J.; Thomas, J. M.
1971-01-01
A computer program for analyzing axisymmetric shells with inertial forces caused by rotation about the shell axis is developed by revising the STARS II shell program. The basic capabilities of the STARS II shell program, such as the treatment of the branched shells, stiffened wall construction, and thermal gradients, are retained.
Directory of Open Access Journals (Sweden)
Khandakar Md Iftekharuddaula
2015-01-01
Full Text Available Submergence tolerant high yielding rice variety was developed using BR11 as a recipient parent applying foreground, phenotypic and background selection approaches. Recombinant selection was found essential to minimize linkage drag by BC2F2 generation. Without recombinant selection, the introgression size in the backcross recombinant lines (BRLs was approximately 15 Mb on the carrier chromosome. The BRLs were found submergence tolerance compared to the check varieties under complete submergence for two weeks at Bangladesh Rice Research Institute, and produced higher yield compared to the isogenic Sub1-line under controlled submerged condition. The BRL IR85260-66-654-Gaz2 was released as BRRI dhan52 in 2010, which was the first high yielding submergence tolerant variety in Bangladesh. BRRI dhan52 produced grain yield ranging from 4.2 to 5.2 t/hm2 under different flash flood prone areas of Bangladesh in three consecutive seasons. The study demonstrated the efficiency of recombinant selection and better adaptability of the newly released submergence tolerant high yielding variety in flash flood prone different areas of the country with respect to submergence tolerance and yield potential.
Tamang, Bishal G; Magliozzi, Joseph O; Maroof, M A Saghai; Fukao, Takeshi
2014-10-01
Complete inundation at the early seedling stage is a common environmental constraint for soybean production throughout the world. As floodwaters subside, submerged seedlings are subsequently exposed to reoxygenation stress in the natural progression of a flood event. Here, we characterized the fundamental acclimation responses to submergence and reoxygenation in soybean at the seedling establishment stage. Approximately 90% of seedlings succumbed during 3 d of inundation under constant darkness, whereas 10 d of submergence were lethal to over 90% of seedlings under 12 h light/12 h dark cycles, indicating the significance of underwater photosynthesis in seedling survival. Submergence rapidly decreased the abundance of carbohydrate reserves and ATP in aerial tissue of seedlings although chlorophyll breakdown was not observed. The carbohydrate and ATP contents were recovered upon de-submergence, but sudden exposure to oxygen also induced lipid peroxidation, confirming that reoxygenation induced oxidative stress. Whole transcriptome analysis recognized genome-scale reconfiguration of gene expression that regulates various signalling and metabolic pathways under submergence and reoxygenation. Comparative analysis of differentially regulated genes in shoots and roots of soybean and other plants defines conserved, organ-specific and species-specific adjustments which enhance adaptability to submergence and reoxygenation through different metabolic pathways. © 2014 John Wiley & Sons Ltd.
Submergence induced changes of molecular species in membrane lipids in Arabidopsis thaliana
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Mulan Wang
2016-06-01
Full Text Available The composition of membrane lipids is sensitive to environmental stresses. Submergence is a type of stress often encountered by plants. However, how the molecular species of membrane lipids respond to submergence has not yet been characterised. In this study, we used a lipidomic approach to profile the molecular species of membrane lipids in whole plants of Arabidopsis thaliana that were completely submerged for three days. The plants survived one day of submergence, after which, we found that the total membrane lipids were only subtly decreased, showing significant decreases of monogalactosyldiacylglycerol (MGDG and phosphatidylcholine (PC and an increase of phosphatidic acid (PA; however, the basic lipid composition was retained. In contrast, three days of submergence caused plants to die, and the membranes deteriorated via the rapid loss of 96% of lipid content together with a 229% increase in PA. The turnover of molecular species from PG and MGDG to PA indicated that submergence-induced lipid changes occurred through PA-mediated degradation. In addition, molecular species of extraplastidic PG degraded sooner than plastidic ones, lyso-phospholipids exhibited various patterns of change, and the double-bond index (DBI remained unchanged until membrane deterioration. Our results revealed the unique changes of membrane lipids upon submergence and suggested that the major cause of the massive lipid degradation could be anoxia.
The Performance and Fouling Control of Submerged Hollow Fiber (HF Systems: A Review
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Ebrahim Akhondi
2017-07-01
Full Text Available The submerged membrane filtration concept is well-established for low-pressure microfiltration (MF and ultrafiltration (UF applications in the water industry, and has become a mainstream technology for surface-water treatment, pretreatment prior to reverse osmosis (RO, and membrane bioreactors (MBRs. Compared to submerged flat sheet (FS membranes, submerged hollow fiber (HF membranes are more common due to their advantages of higher packing density, the ability to induce movement by mechanisms such as bubbling, and the feasibility of backwashing. In view of the importance of submerged HF processes, this review aims to provide a comprehensive landscape of the current state-of-the-art systems, to serve as a guide for further improvements in submerged HF membranes and their applications. The topics covered include recent developments in submerged hollow fiber membrane systems, the challenges and developments in fouling-control methods, and treatment protocols for membrane permeability recovery. The highlighted research opportunities include optimizing the various means to manipulate the hydrodynamics for fouling mitigation, developing online monitoring devices, and extending the submerged HF concept beyond filtration.
Nonlinear dynamo action in a precessing cylindrical container.
Nore, C; Léorat, J; Guermond, J-L; Luddens, F
2011-07-01
It is numerically demonstrated by means of a magnetohydrodynamics code that precession can trigger the dynamo effect in a cylindrical container. When the Reynolds number, based on the radius of the cylinder and its angular velocity, increases, the flow, which is initially centrosymmetric, loses its stability and bifurcates to a quasiperiodic motion. This unsteady and asymmetric flow is shown to be capable of sustaining dynamo action in the linear and nonlinear regimes. The magnetic field thus generated is unsteady and quadrupolar. These numerical evidences of dynamo action in a precessing cylindrical container may be useful for an experiment now planned at the Dresden sodium facility for dynamo and thermohydraulic studies in Germany.
The magnetic properties of the hollow cylindrical ideal remanence magnet
DEFF Research Database (Denmark)
Bjørk, Rasmus
2016-01-01
We consider the magnetic properties of the hollow cylindrical ideal remanence magnet. This magnet is the cylindrical permanent magnet that generates a uniform field in the cylinder bore, using the least amount of magnetic energy to do so. The remanence distribution of this magnet is derived...... and the generated field is compared to that of a Halbach cylinder of equal dimensions. The ideal remanence magnet is shown in most cases to generate a significantly lower field than the equivalent Halbach cylinder, although the field is generated with higher efficiency. The most efficient Halbach cylinder is shown...... to generate a field exactly twice as large as the equivalent ideal remanence magnet....
Analytic descriptions of cylindrical electromagnetic waves in a nonlinear medium.
Xiong, Hao; Si, Liu-Gang; Yang, Xiaoxue; Wu, Ying
2015-06-15
A simple but highly efficient approach for dealing with the problem of cylindrical electromagnetic waves propagation in a nonlinear medium is proposed based on an exact solution proposed recently. We derive an analytical explicit formula, which exhibiting rich interesting nonlinear effects, to describe the propagation of any amount of cylindrical electromagnetic waves in a nonlinear medium. The results obtained by using the present method are accurately concordant with the results of using traditional coupled-wave equations. As an example of application, we discuss how a third wave affects the sum- and difference-frequency generation of two waves propagation in the nonlinear medium.
Analytic descriptions of cylindrical electromagnetic waves in a nonlinear medium
Xiong, Hao; Si, Liu-Gang; Yang, Xiaoxue; Wu, Ying
2015-01-01
A simple but highly efficient approach for dealing with the problem of cylindrical electromagnetic waves propagation in a nonlinear medium is proposed based on an exact solution proposed recently. We derive an analytical explicit formula, which exhibiting rich interesting nonlinear effects, to describe the propagation of any amount of cylindrical electromagnetic waves in a nonlinear medium. The results obtained by using the present method are accurately concordant with the results of using traditional coupled-wave equations. As an example of application, we discuss how a third wave affects the sum- and difference-frequency generation of two waves propagation in the nonlinear medium. PMID:26073066
Confined and interface phonons in combined cylindrical nanoheterosystem
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O.M.Makhanets
2006-01-01
Full Text Available The spectra of all types of phonons existing in a complicated combined nanoheterosystem consisting of three cylindrical quantum dots embedded into the cylindrical quantum wire placed into vacuum are studied within the dielectric continuum model. It is shown that there are confined optical (LO and interface phonons of two types: top surface optical (TSO and side surface optical (SSO modes of vibration in such a nanosystem. The dependences of phonon energies on the quasiwave numbers and geometrical parameters of quantum dots are investigated and analysed.
Orbital trajectory of an acoustic bubble in a cylindrical resonator.
Desjouy, Cyril; Labelle, Pauline; Gilles, Bruno; Bera, Jean-Christophe; Inserra, Claude
2013-09-01
Acoustic cavitation-induced microbubbles in a cylindrical resonator filled with water tend to concentrate into ring patterns due to the cylindrical geometry of the system. The shape of these ring patterns is directly linked to the Bjerknes force distribution in the resonator. Experimental observations showed that cavitation bubbles located in the vicinity of this ring may exhibit a spiraling behavior around the pressure nodal line. This spiraling phenomenon is numerically studied, the conditions for which a single cavitation bubble follows an orbital trajectory are established, and the influences of the acoustic pressure amplitude and the initial bubble radius are investigated.
Ayi, Qiaoli; Zeng, Bo; Liu, Jianhui; Li, Siqi; van Bodegom, Peter M; Cornelissen, Johannes H C
2016-04-10
Flooding imposes stress upon terrestrial plants because it results in oxygen deficiency, which is considered a major problem for submerged plants. A common response of terrestrial plants to flooding is the formation of aquatic adventitious roots. Some studies have shown that adventitious roots on submerged plants are capable of absorbing water and nutrients. However, there is no experimental evidence for the possible oxygen uptake function of adventitious roots or for how important this function might be for the survival of plants during prolonged submergence. This study aims to investigate whether adventitious roots absorb oxygen from the water column, and whether this new function is beneficial to the survival of completely submerged plants. TakingAlternanthera philoxeroides(Mart.) Griseb. as a representative species, the profiling of the underwater oxygen gradient towards living and dead adventitious roots on completely submerged plants was conducted, the oxygen concentration in stem nodes with and without adventitious roots was measured, and the growth, survival and non-structural carbohydrate content of completely submerged plants with and without adventitious roots was investigated. Oxygen profiles in the water column of adventitious roots showed that adventitious roots absorbed oxygen from water. It is found that the oxygen concentration in stem nodes having adventitious roots was higher than that in stem nodes without adventitious roots, which implies that the oxygen absorbed by adventitious roots from water was subsequently transported from the roots to other plant tissues. Compared with plants whose adventitious roots had been pruned, those with intact adventitious roots had slower leaf shedding, slower plant mass reduction, more efficient carbohydrate economy and prolonged survival when completely submerged. The adventitious roots ofA. philoxeroidesformed upon submergence can absorb oxygen from ambient water, thereby alleviating the adverse effects of
Directory of Open Access Journals (Sweden)
Guoyong Jin
2015-01-01
Full Text Available This paper presents elasticity solutions for the vibration analysis of isotropic and orthotropic open shells and plates with arbitrary boundary conditions, including spherical and cylindrical shells and rectangular plates. Vibration characteristics of the shells and plates have been obtained via a unified three-dimensional displacement-based energy formulation represented in the general shell coordinates, in which the displacement in each direction is expanded as a triplicate product of the cosine Fourier series with the addition of certain supplementary terms introduced to eliminate any possible jumps with the original displacement function and its relevant derivatives at the boundaries. All the expansion coefficients are then treated equally as independent generalized coordinates and determined by the Rayleigh-Ritz procedure. To validate the accuracy of the present method and the corresponding theoretical formulations, numerical cases have been compared against the results in the literature and those of 3D FE analysis, with excellent agreements obtained. The effects of boundary conditions, material parameters, and geometric dimensions on the frequencies are discussed as well. Finally, several 3D vibration results of isotropic and orthotropic open spherical and cylindrical shells and plates with different geometry dimensions are presented for various boundary conditions, which may be served as benchmark solutions for future researchers as well as structure designers in this field.
Lefrançois, A
1976-01-01
The method of dimensional analysis is applied to the evaluation of deformation, stress, and ideal buckling strength (which is independent of the values of the elastic range), of shells subject to external pressure. The relations obtained are verified in two examples: a cylindrical ring and a tube with free ends and almost circular cross- section. Further, it is shown how and to what extent the results obtained from model tests can be used to predict the behaviour of geometrically similar shells which are made of the same material, or even of a different material.
Interaction of Submerged Breakwater by a Solitary Wave Using WC-SPH Method
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Afshin Mansouri
2014-01-01
Full Text Available Interaction of a solitary wave and submerged breakwater is studied in a meshless, Lagrangian approach. For this purpose, a two-dimensional smoothed particle hydrodynamics (SPH code is developed. Furthermore, an extensive set of simulations is conducted. In the first step, the generated solitary wave is validated. Subsequently, the interaction of solitary wave and submerged breakwater is investigated thoroughly. Results of the interaction of solitary wave and a submerged breakwater are also shown to be in good agreement with published experimental studies. Afterwards, the effects of the inclination and length of breakwater as well as distance between two breakwaters are evaluated on damping ratio of breakwater.
Oxygen dynamics during submergence in the halophytic stem succulent Halosarcia pergranulata
DEFF Research Database (Denmark)
Pedersen, Ole; Vos, Harrie; Colmer, Timothy David
2006-01-01
This study elucidated O2 dynamics in shoots and roots of submerged Halosarcia pergranulata (Salicornioideae), a perennial halophytic stem succulent that grows on flood-prone mudflats of salt lakes. Oxygen within shoots and roots was measured using microelectrodes, for plants when waterlogged...... the roots, at least during the first several hours (the time period measured) after submergence or when light periods followed darkness. The influence of light on tissue O2 dynamics was confirmed in an experiment on a submerged plant in a salt lake in south-western Australia. In the late afternoon, partial...
Biomechanics of turtle shells: how whole shells fail in compression.
Magwene, Paul M; Socha, John J
2013-02-01
Turtle shells are a form of armor that provides varying degrees of protection against predation. Although this function of the shell as armor is widely appreciated, the mechanical limits of protection and the modes of failure when subjected to breaking stresses have not been well explored. We studied the mechanical properties of whole shells and of isolated bony tissues and sutures in four species of turtles (Trachemys scripta, Malaclemys terrapin, Chrysemys picta, and Terrapene carolina) using a combination of structural and mechanical tests. Structural properties were evaluated by subjecting whole shells to compressive and point loads in order to quantify maximum load, work to failure, and relative shell deformations. The mechanical properties of bone and sutures from the plastral region of the shell were evaluated using three-point bending experiments. Analysis of whole shell structural properties suggests that small shells undergo relatively greater deformations before failure than do large shells and similar amounts of energy are required to induce failure under both point and compressive loads. Location of failures occurred far more often at sulci than at sutures (representing the margins of the epidermal scutes and the underlying bones, respectively), suggesting that the small grooves in the bone created by the sulci introduce zones of weakness in the shell. Values for bending strength, ultimate bending strain, Young's modulus, and energy absorption, calculated from the three-point bending data, indicate that sutures are relatively weaker than the surrounding bone, but are able to absorb similar amounts of energy due to higher ultimate strain values. Copyright © 2012 Wiley Periodicals, Inc.
Directory of Open Access Journals (Sweden)
Fumiko Iwanaga
2015-04-01
Full Text Available Aim of study: Withstanding total submergence and reaeration following submergence is essential for the survival and establishment of wetland species. We focused on “LOES–low oxygen escape syndrome” and “LOQS–low oxygen quiescence syndrome” and compared tolerances to total submergence among wetland woody species differing in morphological adaptation to soil flooding. Area of study, materials and methods: This study examined the survival of 2-year-old saplings of Taxodium distichum and Metasequioia glyptostroboides (LOQS species, and Alnus japonica (LOES species, during and after total submergence. Saplings were completely submerged, then de-submerged to determine trends in survival and growth Main results: The M. glyptostroboides and A. japonica saplings could not survive prolonged submergence for more than 8 weeks, whereas saplings of T. distichum survived for over 2 years. Submerged saplings of all species showed no significant growth or modifications in morphology and anatomy under water, such as shoot elongation, adventitious root formation, and/or aerenchyma development. All T. distichum saplings that were de-submerged in the second year had the same pattern of shoot growth regardless of differences in timing and seasonality of de-submergence. Wood formation in T. distichum saplings ceased during submergence and resumed after de-submergence in spring and summer, but not in autumn. Research highlights: T. distichum saplings, which survived longer submergence periods than A. japonica and M. glyptostroboides, had physiological characteristics, such as suspension of growth and metabolism, which allowed survival of protracted total submergence (at least 2 years when saplings were immersed during the dormant stage before leaf flushing.
Gravity balanced compliant shell mechanisms
Radaelli, G.; Herder, J.L.
2017-01-01
The research on compliant shell mechanisms is a new and promising expansion of the well established compliant mechanisms research area. Benefits of compliant shell mechanisms include being spatial and slender, having organic shapes and their high tailorability of the load-displacement response.
Core-shell nanostructured catalysts.
Zhang, Qiao; Lee, Ilkeun; Joo, Ji Bong; Zaera, Francisco; Yin, Yadong
2013-08-20
Novel nanotechnologies have allowed great improvements in the syn-thesis of catalysts with well-controlled size, shape, and surface properties. Transition metal nanostructures with specific sizes and shapes, for instance, have shown great promise as catalysts with high selectivities and relative ease of recycling. Researchers have already demonstrated new selective catalysis with solution-dispersed or supported-metal nanocatalysts, in some cases applied to new types of reactions. Several challenges remain, however, particularly in improving the structural stability of the catalytic active phase. Core-shell nanostructures are nanoparticles encapsulated and protected by an outer shell that isolates the nanoparticles and prevents their migration and coalescence during the catalytic reactions. The synthesis and characterization of effective core-shell catalysts has been at the center of our research efforts and is the focus of this Account. Efficient core-shell catalysts require porous shells that allow free access of chemical species from the outside to the surface of nanocatalysts. For this purpose, we have developed a surface-protected etching process to prepare mesoporous silica and titania shells with controllable porosity. In certain cases, we can tune catalytic reaction rates by adjusting the porosity of the outer shell. We also designed and successfully applied a silica-protected calcination method to prepare crystalline shells with high surface area, using anatase titania as a model system. We achieved a high degree of control over the crystallinity and porosity of the anatase shells, allowing for the systematic optimization of their photocatalytic activity. Core-shell nanostructures also provide a great opportunity for controlling the interaction among the different components in ways that might boost structural stability or catalytic activity. For example, we fabricated a SiO₂/Au/N-doped TiO₂ core-shell photocatalyst with a sandwich structure that showed
Directory of Open Access Journals (Sweden)
Michael A. Sprague
1999-01-01
Full Text Available The title problem is solved through extension of a method previously formulated for plane step-wave excitation, which employs generalized Fourier series augmented by partial closure of those series at early time. The extension encompasses both plane and spherical incident waves with step-exponential pressure profiles. The effects of incident-wave curvature and profile decay rate on response behavior are examined. A method previously developed for assessing the discrepancy between calculated and measured response histories is employed to evaluate the convergence of the truncated series solutions. Also studied is the performance of doubly-asymptotic approximations. Finally, the efficacy of modified Cesàro summation for improving the convergence of series solutions is examined. The documented computer program that produced the numerical results appearing in this paper, SPHSHK/MODSUM, may be down-loaded from the Web site http://saviac.xservices.com.
Development of new cylindrical magnetrons for industrial use
Clayton, B
2000-01-01
four-fold system. In an attempt to tackle this problem, a finite element model of the magnetic field generated by the magnetic assembly was built, run and verified. Changes were made to this model, and a new .magnet assembly was built and tested based on the results obtained. This did not lead to a final solution of the problem, but has set bounds within which the solution must lie. A number of alternative techniques were considered and tested with a view to the construction of a cylindrical sputtering device. This device was required to be capable of depositing tribological coatings inside approximately cylindrical substrates of diameters less than 100mm, in an industrial situation. A cylindrical magnetron device was designed, and constructed as a prototype, using a magnetic assembly inside a cylindrical target with outside diameter (o.d.) 40mm. Two alternative magnetic assemblies were tested, and found to have complimentary advantages. The magnetron characteristics of the device were tested, as were key pro...
Magnetization curves for general cylindrical samples in a transverse ...
Indian Academy of Sciences (India)
The ﬂux-fronts are to be determined by solving a system of nonlinear ordinary differential equations for the coefﬁcients. Retaining only a certain ﬁnite number of leading coefﬁcients we get an approximate solution. The procedure is illustrated by considering two cylindrical samples – one with an elliptical cross-section and the ...
La production des cylindres chez Pathé
Chamoux, Henri
2005-01-01
Cette histoire de la production des cylindres chez Pathé a été publiée par Henri Chamoux, inventeur de l’archéophone, dans les Bulletins des adhérents de l'AFAS numéros 14 (automne 1999), 15 (hiver 1999), 16 (printemps-été 2000), 17 (automne 2000).
A cylindrical drift chamber with azimuthal and axial position readout
Energy Technology Data Exchange (ETDEWEB)
Bar-Yam, Z.; Cummings, J.P.; Dowd, J.P.; Eugenio, P.; Hayek, M.; Kern, W.; King, E.; Shenhav, N.; Chung, S.U.; Hackenburg, R.W.; Olchanski, C.; Weygand, D.P.; Willutzki, H.J.; Brabson, B.B.; Crittenden, R.R.; Dzierba, A.R.; Gunter, J.; Lindenbusch, R.; Rust, D.R.; Scott, E.; Smith, P.T.; Sulanke, T.; Teige, S.; Denisov, S.; Dushkin, A.; Kochetkov, V.; Lipaev, V.; Popov, A.; Shein, I.; Soldatov, A.; Anoshina, E.V.; Bodyagin, V.A.; Demianov, A.I.; Gribushin, A.M.; Kodolova, O.L.; Korotkikh, V.L.; Kostin, M.A.; Ostrovidov, A.I.; Sarycheva, L.I.; Sinev, N.B.; Vardanyan, I.N.; Yershov, A.A.; Adams, T.; Bishop, J.M.; Cason, N.M.; Sanjari, A.H.; LoSecco, J.M.; Manak, J.J.; Shephard, W.D.; Stienike, D.L.; Taegar, S.A.; Thompson, D.R.; Brown, D.S.; Pedlar, T.; Seth, K.K.; Wise, J.; Zhao, D.; Adams, G.S.; Napolitano, J.; Nozar, M.; Smith, J.A.; Witkowski, M. [Massachusetts Univ., North Dartmouth, MA (United States)]|[Brookhaven National Laboratory, Upton, L.I., NY 11973 (United States)]|[Indiana University, Bloomington, IN 47405 (United States)]|[Institute for High Energy Physics, Protvino (Russian Federation)]|[Institute of Nuclear Physics, Moscow State University, Moscow (Russian Federation)]|[University of Notre Dame, Notre Dame, IN 46556 (United States)]|[Northwestern University, Evanston, IL 60208 (United States)]|[Rensselaer Polytechnic Institute, Troy, NY 12180 (United States)
1997-02-21
A cylindrical multiwire drift chamber with axial charge-division has been constructed and used in experiment E852 at Brookhaven National Laboratory. It serves as a trigger element and as a tracking device for recoil protons in {pi}{sup -}p interactions. We describe the chamber`s design considerations, details of its construction, electronics, and performance characteristics. (orig.).
Static Solutions of Einstein's Equations with Cylindrical Symmetry
Trendafilova, C. S.; Fulling, S. A.
2011-01-01
In analogy with the standard derivation of the Schwarzschild solution, we find all static, cylindrically symmetric solutions of the Einstein field equations for vacuum. These include not only the well-known cone solution, which is locally flat, but others in which the metric coefficients are powers of the radial coordinate and the spacetime is…
The cylindrical or tubiliform glands of Nephila clavipes.
Candelas, G C; Ortiz, A; Molina, C
1986-02-01
The cylindrical or tubiliform glands of the spider Nephila clavipes have been studied and compared to the large ampullates on which we have previously reported. The three pairs of cylindrical or tubiliform glands secrete the fibroin for the organism's egg case. Their solubilized luminar contents migrate as a homogeneous band in Sodium dodecyl sulfate polyacrylamide gel electrophoresis and turn out to be a larger protein than that produced by the large ampullates. The excised cylindrical glands remain metabolically active for several hours in a simple culture medium, where fibroin synthesis can be monitored through the incorporation of 14C alanine. The glands' response to a fibroin production stimulus does not reach the magnitude displayed by the large ampullates, but this is to be expected since their products supply different functions in this organism. This fibroin also seems to be elongated discontinuously. Translational pauses have been detected in the secretory epithelium of cylindrical and large ampullate glands of Nephila as well as in the silk glands of Bombyx mori. Since these glands produce the fibroin for the females egg case, they should prove to be an interesting model system.
Detailed analysis of the intracavity phenomena inside a cylindrical microresonator
Klunder, D.J.W.; Balistreri, M.L.M.; Blom, F.C.; Hoekstra, Hugo; Driessen, A.; Kuipers, L.; van Hulst, N.F.
2002-01-01
Based on a rigorous analysis of the intensity distribution inside a cylindrical microresonator (MR), a detailed description of the wavelength and spatial dependence of the intracavity intensity is given. The theory is in accordance with photon scanning tunneling microscopy (PSTM) of an integrated optics MR. Good agreement between the theory and the PSTM measurements is found.
Detailed analysis of the intracavity phenomena inside a cylindrical microresonator
Klunder, D.J.W.; Balistreri, M.L.M.; Blom, F.C.; Hoekstra, Hugo; Driessen, A.; Kuipers, L.; van Hulst, N.F.
2002-01-01
Based on a rigorous analysis of the intensity distribution inside a cylindrical microresonator (MR), a detailed description of the wavelength and spatial dependence of the intracavity intensity is given. The theory is in accordance with photon scanning tunneling microscopy (PSTM) of an integrated
Electron cyclotron resonance heating in a short cylindrical plasma ...
Indian Academy of Sciences (India)
Electron cyclotron resonance (ECR) plasma is produced and studied in a small cylindrical system. Microwave power is delivered by a CW magnetron at 2.45 GHz in TE10 mode and launched radially to have extraordinary (X) wave in plasma. The axial magnetic field required for ECR in the system is such that the first two ...
Magnetoresistance of cylindrical nanowires with artificial pinning site
Vidal, Enrique Vilanova
2015-05-01
New concepts of magnetic memory devices are exploiting the movement of data bits by current induced domain wall motion. This concept has been widely explored with rectangular nanowires (NWs) or stripes both theoretically and experimentally [1]. In the case of cylindrical NWs not much progress has been made on the experimental side, despite its promising advantages like the absence of Walker breakdown [2].
Effect of bimodularity on frequency response of cylindrical panels ...
Indian Academy of Sciences (India)
M. Senthilkumar (Newgen Imaging) 1461 1996 Oct 15 13:05:22
ASME J. Vibration, Acoustics, Stress and Reliability in Design 107: 92–97. Doong J L, Fung C P 1988 Vibration and buckling of bimodulus laminated plates according to a higher-order plate theory. J. Sound Vib. 125: 325–339. Khan K, Patel B P, Nath Y 2007 Free vibration of bimodulus laminated angle-ply cylindrical ...
The Volume of a Torus Using Cylindrical and Spherical Coordinates
Farmer, Jim
2005-01-01
The author of this article, while recently working through some problem sets on determining volumes by triple integrals in cylindrical and spherical coordinate systems, realized that, although the textbook he was using included many interesting problems involving spheres, cylinders and cones and the increasingly complex solids that arose from the…
Elastic waves along a cylindrical borehole in a poroelastic medium ...
Indian Academy of Sciences (India)
The propagation of elastic waves along a cylindrical borehole filled with/without liquid and embedded in an infinite porous medium saturated by two immiscible fluids has been studied. The theory of porous media saturated by two immiscible fluids developed by Tuncay and Corapcioglu (1997) is employed. Frequency ...
Employing a cylindrical single crystal in gas-surface dynamics
Hahn, C.; Shan, J.; Liu, Y.; Berg, O.; Kleijn, A. W.; Juurlink, L. B. F.
2012-01-01
We describe the use of a polished, hollow cylindrical nickel single crystal to study effects of step edges on adsorption and desorption of gas phase molecules. The crystal is held in an ultra-high vacuum apparatus by a crystal holder that provides axial rotation about a [100] direction, and a
Surface waves in a cylindrical borehole through partially-saturated ...
Indian Academy of Sciences (India)
M D Sharma
2018-02-14
Feb 14, 2018 ... Keywords. Cylindrical waves; phase velocity; dispersion; porous solid; partial saturation; multiphase pore-fluid. Nomenclature t. Time ... on Biot's theory of poroelasticity (Biot 1956), was observed. In a later study, Chao et al. ... model and used it to obtain the analytical solution for wave propagation in a 1-D ...
Development of a cylindrical gas-fired furnace for reycling ...
African Journals Online (AJOL)
This study presents the development of a cylindrical gas-fired furnace, which could be used for recycling aluminum in small-scale foundries in Nigeria. The crucible, combustion chamber, suspension shaft and bearings were appropriately sized. The furnace chamber was 410 mm high and 510 mm diameter and had a ...
A winning strategy for 3 x n Cylindrical Hex
DEFF Research Database (Denmark)
Huneke, S. C.; Hayward, R.; Toft, Bjarne
2014-01-01
For Cylindrical Hex on a board with circumference 3, we give a winning strategy for the end-to-end player. This is the first known winning strategy for odd circumference at least 3, answering a question of David Gale. (C) 2014 Elsevier B.V. All rights reserved....
Phase transition properties of a cylindrical ferroelectric nanowire
Indian Academy of Sciences (India)
In the present paper, we apply the mean-field theory to investigate the phase transition properties of a cylindrical ferroelectric nanowire by taking into account two different exchange interactions and two different transverse field parameters in the. TIM. The effects of various parameters on the phase diagrams are given, and ...
Coupled dilaton and electromagnetic field in cylindrically symmetric ...
Indian Academy of Sciences (India)
An exact solution is obtained for coupled dilaton and electromagnetic ﬁeld in a cylindrically symmetric spacetime where an axial magnetic ﬁeld as well as a radial electric ﬁeld both are present. Depending on the choice of the arbitrary constants our solution reduces either to dilatonic gravity with pure electric ﬁeld or to that ...
Fabrication of composite shell structure for advanced space transportation
Penton, A. P.; Johnson, R., Jr.; Freeman, V. L.
1978-01-01
It is pointed out that future space missions, such as those involving spacecraft and structural assemblies to be used in geosynchronous orbits, will require ultralightweight composite structures to achieve maximum payloads. Of equal importance is the requirement to provide designs that are cost-competitive with metal designs. For space structures that must resist buckling, graphite-epoxy materials offer an attractive potential for providing lightweight, low-cost structural components that will meet future space mission requirements. A description is presented of a program which was conducted to evaluate the merits of graphite-epoxy cylindrical shells and to continue the development of a design data base for ultralightweight structures. An objective of the program was to design, fabricate, and test a corrugated graphite-epoxy cylinder 10 ft in diameter and 10 ft long.
Outer Continental Shelf Submerged Lands Act Boundary - Atlantic Region NAD83
Bureau of Ocean Energy Management, Department of the Interior — This data set contains the Submerged Lands Act (SLA) boundary line (also known as State Seaward Boundary (SSB), or Fed State Boundary) in ESRI shapefile formats for...
The Development of a Composite Consumable Insert for Submerged ARC Welding
National Research Council Canada - National Science Library
1980-01-01
.... When the submerged arc process was utilized to weld the butt joint in large flat plate structures, the repositioning of the plate for welding of the reverse side was a costly time consuming procedure...
Meta Modelling of Submerged-Arc Welding Design based on Fuzzy Algorithm
Song, Chang-Yong; Park, Jonghwan; Goh, Dugab; Park, Woo-Chang; Lee, Chang-Ha; Kim, Mun Yong; Kang, Jinseo
2017-12-01
Fuzzy algorithm based meta-model is proposed for approximating submerged-arc weld design factors such as weld speed and weld output. Orthogonal array design based on the submerged-arc weld numerical analysis is applied to the proposed approach. The nonlinear finite element analysis is carried out to simulate the submerged-arc weld numerical analysis using thermo-mechanical and temperature-dependent material properties for general mild steel. The proposed meta-model based on fuzzy algorithm design is generated with triangle membership functions and fuzzy if-then rules using training data obtained from the Taguchi orthogonal array design data. The aim of proposed approach is to develop a fuzzy meta-model to effectively approximate the optimized submerged-arc weld factors. To validate the meta-model, the results obtained from the fuzzy meta-model are compared to the best cases from the Taguchi orthogonal array.
Large-Scale Submerged Aquatic Vegetation Restoration in Chesapeake Bay: Status Report, 2003-2006
National Research Council Canada - National Science Library
Shafer, Deborah J; Bergstrom, Peter
2008-01-01
In 2003, the U.S. Army Engineer Research and Development Center (ERDC) and the National Oceanic and Atmospheric Administration Chesapeake Bay Office began a comprehensive research effort to restore submerged aquatic vegetation (SAV...
Flow Velocity and Morphology of a Submerged Patch of the Aquatic Species
Cornacchia, L.; Licci, S.; van de Koppel, J.; van der Wal, D.; Wharton, G.; Puijalon, S.; Bouma, T.J.
2016-01-01
The interaction between macrophytes and hydrodynamic conditions is animportant feature in many aquatic ecosystems. Submerged macrophytes can formmonospecific patches that interact with the flow and alter current velocity; withinthe same vegetation patch, plants are exposed to different levels of
Uncalibrated EAARL-B Submerged Topography--Fort Lauderdale, Florida, 2014 (GEOID12A)
U.S. Geological Survey, Department of the Interior — Binary point-cloud data of a portion of the submerged environs of Fort Lauderdale, Florida, were produced from remotely sensed, geographically referenced elevation...
EAARL-B Submerged Topography - Saint Croix, U.S. Virgin Islands, 2014
U.S. Geological Survey, Department of the Interior — ASCII XYZ point cloud data for a portion of the submerged environs of Saint Croix, U.S. Virgin Islands, was produced from remotely sensed, geographically referenced...
EAARL-B Submerged TopographyÂCrocker Reef, Florida, 2014
U.S. Geological Survey, Department of the Interior — ASCII XYZ point cloud data for a portion of the submerged environs of Crocker Reef, Florida, were produced from remotely sensed, geographically referenced elevation...
Calibrated EAARL-B Submerged Topography--Fort Lauderdale, Florida, 2014 (GEOID12A)
U.S. Geological Survey, Department of the Interior — Binary point-cloud data of a portion of the submerged environs of Fort Lauderdale, Florida, were produced from remotely sensed, geographically referenced elevation...
US Fish and Wildlife Service, Department of the Interior — This Environmental Assessment is an analysis of five alternatives developed to address themanagement of the submerged aquatic plants of Banks Lake on Banks Lake...
2012-11-01
Submerged Aquatic Vegetation (SAV) is an important component in any estuarine ecosystem. As such, it is regulated by federal and state agencies as a jurisdictional resource, where impacts to SAV are compensated through mitigation. Historically, tradi...
Sasidharan, R.; Mustroph, A.; Boonman, A.; Akman, M.; Ammerlaan, A.M.H.; Breit, T.M.; Schranz, M.E.; Voesenek, L.A.C.J.; Tienderen, van P.H.
2013-01-01
Complete submergence represses photosynthesis and aerobic respiration, causing rapid mortality in most terrestrial plants. However, some plants have evolved traits allowing them to survive prolonged flooding, such as species of the genus Rorippa, close relatives of Arabidopsis (Arabidopsis
Sasidharan, R.; Mustroph, A.; Boonman, A.; Akman, M.; Ammerlaan, A.M.H.; Breit, T.M.; Schranz, M.E.; Voesenek, L.A.C.J.; van Tienderen, P.H.
2013-01-01
Complete submergence represses photosynthesis and aerobic respiration, causing rapid mortality in most terrestrial plants. However, some plants have evolved traits allowing them to survive prolonged flooding, such as species of the genus Rorippa, close relatives of Arabidopsis (Arabidopsis
Sandsten, H.; Klaassen, M.R.J.
2008-01-01
Compared to terrestrial environments, grazing intensity on belowground plant parts may be particularly strong in aquatic environments, which may have great effects on plant-community structure. We observed that the submerged macrophyte, Potamogeton pectinatus, which mainly reproduces with tubers,
EAARL-B Submerged TopographyÂSaint Thomas, U.S. Virgin Islands, 2014
U.S. Geological Survey, Department of the Interior — ASCII XYZ point cloud data for a portion of the submerged environs of Saint Thomas, U.S. Virgin Islands, was produced from remotely sensed, geographically referenced...
Uncalibrated EAARL-B Submerged Topography--Fort Lauderdale, Florida, 2014 (WGS84)
U.S. Geological Survey, Department of the Interior — Binary point-cloud data of a portion of the submerged environs of Fort Lauderdale, Florida, were produced from remotely sensed, geographically referenced elevation...
Calibrated EAARL-B Submerged Topography--Fort Lauderdale, Florida, 2014 (WGS84)
U.S. Geological Survey, Department of the Interior — Binary point-cloud data of a portion of the submerged environs of Fort Lauderdale, Florida, were produced from remotely sensed, geographically referenced elevation...
Outer Continental Shelf Submerged Lands Act Boundary - Pacific Region - West Coast NAD83
Bureau of Ocean Energy Management, Department of the Interior — This data set contains the Submerged Lands Act (SLA)boundary line (also known as the State Seaward Boundary (SSB) and Fed State Boundary) for the BOEM Pacific Region...
Process Modeling and Optimization of a Submerged Arc Furnace for Phosphorus Production
Scheepers, E.; Yang, Y.; Adema, A.T.; Boom, R.; Reuter, M.A.
2010-01-01
This article presents a process model of a phosphorus-producing, submerged arc furnace. The model successfully incorporates accurate, multifield thermodynamic, kinetic, and industrial data with computational flow dynamic calculations and thus further unifies the sciences of kinetics and equilibrium
EAARL-B Submerged Topography - Saint Croix and Saint Thomas, U.S. Virgin Islands, 2014
National Oceanic and Atmospheric Administration, Department of Commerce — Binary point-cloud data for part of the submerged environs of Saint Croix and Saint Thomas, U.S. Virgin Islands, were produced from remotely sensed, geographically...