THz parallel-plate waveguides with resonant cavities
DEFF Research Database (Denmark)
Reichel, Kimberly S.; Astley, Victoria; Iwaszczuk, Krzysztof;
2015-01-01
We characterize the terahertz resonance due to a cavity inside aparallel-plate waveguide, and discuss its use for refractive index sensing. Insidethe waveguide, we observe a broadband field enhancement associated with thisnarrowband resonance. © 2015 OSA....
A plate waveguide design for ultrasonic flow measurements in hostile environments
Laws, M.; Ramadas, S. N.; Dixon, S.
2013-01-01
A novel plate waveguide has been designed in order to act as a low dispersion thermal buffer for application in flow metering. The proposed waveguide consists of a series of thin flat rectangular metallic plates which can behave as waveguides with limited dispersion. Extensive modeling based on the finite element method has been carried out to study the proposed waveguide design. A prototype waveguide has been built in order to carry out transmit-receive experiments in a water tank which have shown that, without backing on the transducer or impedance matching on the radiating face, it is possible to detect a signal through these waveguides. Preliminary results are encouraging, however, there is still much design optimization is required to make this device work for a given application.
Multipactor saturation in parallel-plate waveguides
Energy Technology Data Exchange (ETDEWEB)
Sorolla, E.; Mattes, M. [Ecole Polytechnique Federale de Lausanne, Laboratoire d' Electromagnetisme et d' Acoustique (LEMA), Station 11, CH-1015 Lausanne (Switzerland)
2012-07-15
The saturation stage of a multipactor discharge is considered of interest, since it can guide towards a criterion to assess the multipactor onset. The electron cloud under multipactor regime within a parallel-plate waveguide is modeled by a thin continuous distribution of charge and the equations of motion are calculated taking into account the space charge effects. The saturation is identified by the interaction of the electron cloud with its image charge. The stability of the electron population growth is analyzed and two mechanisms of saturation to explain the steady-state multipactor for voltages near above the threshold onset are identified. The impact energy in the collision against the metal plates decreases during the electron population growth due to the attraction of the electron sheet on the image through the initial plate. When this growth remains stable till the impact energy reaches the first cross-over point, the electron surface density tends to a constant value. When the stability is broken before reaching the first cross-over point the surface charge density oscillates chaotically bounded within a certain range. In this case, an expression to calculate the maximum electron surface charge density is found whose predictions agree with the simulations when the voltage is not too high.
Finite element analysis of optical waveguides
Mabaya, N.; Lagasse, P. E.; Vandenbulcke, P.
1981-06-01
Several finite element programs for the computation of the guided modes of optical waveguides are presented. The advantages and limitations of a very general program for the analysis of anisotropic guides are presented. A possible solution to the problem of the spurious numerical modes, encountered when calculating higher order modes, is proposed. For isotropic waveguides, it is shown that both EH- and HE-type modes can be very accurately approximated by two different scalar finite element programs. Finally, a boundary perturbation method is outlined that makes it possible to calculate the attenuation coefficient of leaky modes in single material guides, starting from a finite element calculation.
Time-resolved THz spectroscopy in a parallel plate waveguide
DEFF Research Database (Denmark)
Cooke, David; Jepsen, Peter Uhd
2009-01-01
We demonstrate time-resolved terahertz spectroscopy inside a novel parallel plate waveguide where one of the metallic plates is replaced by a transparent conducting oxide. Considerable improvements to the waveguide loss coefficient are shown, with a power absorption coefficient of 4cm-1 at 0.5 THz....... The time resolution of the technique is shown to be limited by the spatial excitation profile, which for sharply focused beams can approach ~1 ps time scales....
An efficient rectangular plate element
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
A new 12-parameter rectangular plate element is presented by useof the double set parameter method. The error in the energy norm is of order O(h2), one order higher than the commonly used Adini nonconforming element.
S/Ka Dichroic Plate with Rounded Corners for NASA's 34-m Beam-Waveguide Antenna
Veruttipong, W.; Khayatian, B.; Imbriale, W.
2016-02-01
An S-/Ka-band frequency selective surface (FSS) or a dichroic plate is designed, manufactured, and tested for use in NASA's Deep Space Network (DSN) 34-m beam-waveguide (BWG) antennas. Due to its large size, the proposed dichroic incorporates a new design feature: waveguides with rounded corners to cut cost and allow ease of manufacturing the plate. The dichroic is designed using an analysis that combines the finite-element method (FEM) for arbitrarily shaped guides with the method of moments and Floquet mode theory for periodic structures. The software was verified by comparison with previously measured and computed dichroic plates. The large plate was manufactured with end-mill machining. The RF performance was measured and is in excellent agreement with the analytical results. The dichroic has been successfully installed and is operational at DSS-24, DSS-34, and DSS-54.
Loveday, Philip W
2007-10-01
A finite-element modeling procedure for computing the frequency response of piezoelectric transducers attached to infinite constant cross-section waveguides, as encountered in guided wave ultrasonic inspection, is presented. Two-dimensional waveguide finite elements are used to model the waveguide. Conventional three-dimensional finite elements are used to model the piezoelectric transducer. The harmonic forced response of the waveguide is used to obtain a dynamic stiffness matrix (complex and frequency dependent), which represents the waveguide in the transducer model. The electrical and mechanical frequency response of the transducer, attached to the waveguide, can then be computed. The forces applied to the waveguide are calculated and are used to determine the amplitude of each mode excited in the waveguide. The method is highly efficient compared to time integration of a conventional finite-element model of a length of waveguide. In addition, the method provides information about each mode that is excited in the waveguide. The method is demonstrated by modeling a sandwich piezoelectric transducer exciting a waveguide of rectangular cross section, although it could be applied to more complex situations. It is expected that the modeling method will be useful during the optimization of piezoelectric transducers for exciting specific wave propagation modes in waveguides.
Non-invasive terahertz field imaging inside parallel plate waveguides
DEFF Research Database (Denmark)
Iwaszczuk, Krzysztof; Andryieuski, Andrei; Lavrinenko, Andrei
2011-01-01
We present a non-invasive broadband air photonic method of imaging of the electric field of THz pulses propagating inside a tapered parallel plate waveguide. The method is based on field-enhanced second harmonic generation of the fundamental laser beam in an external electric field. We apply...
Terahertz field imaging inside tapered parallel plate waveguides
DEFF Research Database (Denmark)
Iwaszczuk, Krzysztof; Andryieuski, Andrei; Lavrinenko, Andrei
We present a non-invasive broadband air photonic method of terahertz field imaging inside a tapered parallel plate waveguide. The method is based on the terahertz-enhanced second harmonic generation of the fundamental laser beam in an external electric field. We also demonstrate the direct...
Liu, Jiamin; Liang, Huawei; Zhang, Min; Su, Hong
2014-09-10
We report on the broadband terahertz (THz) transmission within a symmetrical plastic film coated parallel-plate waveguide. We theoretically study the antiresonant reflecting mechanism of the waveguide, and we find that the broadband THz wave can transmit in this waveguide with ultralow loss. The loss of the TM mode in this waveguide can be 4 orders of magnitude lower than the uncoated parallel-plate waveguide. The transmission bandwidth of this waveguide is up to 5.12 THz. We further show the mode field distributions which explain the loss mechanism.
Wave propagation in parallel-plate waveguides filled with nonlinear left-handed material
Institute of Scientific and Technical Information of China (English)
Burhan Zamir; Rashid Ali
2011-01-01
A theoretical investigation of field components for transverse electric mode in the parallel-plate waveguides has been studied. In this analysis two different types of waveguide structures have been discussed, i.e., (a) normal good/perfect conducting parallel-plate waveguide filled with nonlinear left-handed material and (b) high-temperature-superconducting parallel-plate waveguide filled with nonlinear left-handed material. The dispersion relations of transverse electric mode have also been discussed for these two types of waveguide structures.
An efficient rectangular plate element
Institute of Scientific and Technical Information of China (English)
SHI; Zhongci
2001-01-01
［1］Shi Zhong-ci, On the accuracy of the quasi-conforming and generalize conforming finite elements, Chin. Ann. Math., 1990, 11B: 148.［2］Shi Zhong-ci, Chen Shao-chun, Huang Hong-ci, Plate elements with high accuracy, Collec. Geom. Anal. Math. Phys. (ed. Li Ta-Tsien), Singapore: World Scientific, 1997, 155—164.［3］Chen Shao-chun, Shi Zhong-ci, Double set parameter method for the construction of the element stiffness matrix, Mathematica Numerica Sinica (in Chinese), 1991, 13: 286.［4］Ciarlet, P., The Finite Element Method for Elliptic Problems, Amsterdam: North-Holland, 1978.
Broadband terahertz polarization rotator based on a twisted parallel plate waveguide
DEFF Research Database (Denmark)
Kristensen, T. Bjørk; Iwaszczuk, Krzysztof; Jepsen, Peter Uhd
2016-01-01
A broadband polarization rotator for terahertz waves is developed by 3D printing. The device is based on a twisted parallel plate waveguide.......A broadband polarization rotator for terahertz waves is developed by 3D printing. The device is based on a twisted parallel plate waveguide....
Institute of Scientific and Technical Information of China (English)
Bahattin Kanber; O.Yavuz Bozkurt
2006-01-01
In this work,the finite element analysis of the elasto-plastic plate bending problems is carried out using transition rectangular plate elements.The shape functions of the transition plate elements are derived based on a practical rule.The transition plate elements are all quadrilateral and can be used to obtain efficient finite element models using minimum number of elements.The mesh convergence rates of the models including the transition elements are compared with the regular element models.To verify the developed elements,simple tests are demonstrated and various elasto-plastic problems are solved.Their results are compared with ANSYS results.
ON FINITE ELEMENT METHODS FOR INHOMOGENEOUS DIELECTRIC WAVEGUIDES
Institute of Scientific and Technical Information of China (English)
Zhiming Chen; Jian-hua Yuan
2004-01-01
We investigate the problem of computing electromagnetic guided waves in a closed,inhomogeneous, pillared three-dimensional waveguide at a given frequency. The problem is formulated as a generalized eigenvalue problem. By modifying the sesquilinear form associated with the eigenvalue problem, we provide a new convergence analysis for the finite element approximations. Numerical results are reported to illustrate the performance of the method.
New 2D diffraction model and its applications to terahertz parallel-plate waveguide power splitters
Zhang, Fan; Song, Kaijun; Fan, Yong
2017-02-01
A two-dimensional (2D) diffraction model for the calculation of the diffraction field in 2D space and its applications to terahertz parallel-plate waveguide power splitters are proposed in this paper. Compared with the Huygens-Fresnel principle in three-dimensional (3D) space, the proposed model provides an approximate analytical expression to calculate the diffraction field in 2D space. The diffraction filed is regarded as the superposition integral in 2D space. The calculated results obtained from the proposed diffraction model agree well with the ones by software HFSS based on the element method (FEM). Based on the proposed 2D diffraction model, two parallel-plate waveguide power splitters are presented. The splitters consist of a transmitting horn antenna, reflectors, and a receiving antenna array. The reflector is cylindrical parabolic with superimposed surface relief to efficiently couple the transmitted wave into the receiving antenna array. The reflector is applied as computer-generated holograms to match the transformed field to the receiving antenna aperture field. The power splitters were optimized by a modified real-coded genetic algorithm. The computed results of the splitters agreed well with the ones obtained by software HFSS verify the novel design method for power splitter, which shows good applied prospects of the proposed 2D diffraction model.
Performance test of a plate-type ultrasonic waveguide sensor in sodium
Joo, Young-Sang; Bae, Jin-Ho; Kim, Hoe-Woong; Kim, Jong-Bum
2013-01-01
A plate-type ultrasonic waveguide sensor that uses the A0-mode leaky Lamb waves has been developed for under-sodium viewing of the reactor core and in-vessel structures in the sodiumcooled fast reactor. A new ultrasonic waveguide sensor that has beryllium (Be) and nickel (Ni) coating layers on its surfaces is proposed for the enhancement of the ultrasonic beam radiation and wetting capabilities in sodium. The sodium test facility with a glove box system and a sodium test loop has been designed and constructed to carry out the performance test of the developed ultrasonic waveguide sensor in a sodium environment. A 1.7 m long ultrasonic waveguide sensor with beryllium and nickel coating layers was designed and manufactured. The performance tests were carried out to evaluate the ultrasonic beam radiation characteristics and C-scan imaging resolution of the plate-type ultrasonic waveguide sensor in sodium.
ALL-OPTICAL CONTROL OF THZ RADIATION IN PARALLEL PLATE WAVEGUIDES
DEFF Research Database (Denmark)
2010-01-01
The invention relates to control of THz radiation in parallel plate waveguides (PPWG) by forming components in the waveguide by use of optical radiation pulses. Patterns of excited regions induced in the PPWG by an optical excitation pulses changes the electromagnetic properties of the waveguide...... medium in the THz regime, thereby forming transient passive and active components for controlling THz radiation signals. The excitation can be generation of free charge carriers in a semiconductor material in the PPWG, to create metallic regions that form mirrors, lenses or photonic crystal structures......-on-a-chip applications. The optical and THz radiation can be ultrashort pulses with picosecond or femtosecond pulse durations. L...
Ultrasonic Beam Radiation of an A0 Leaky Lamb Wave in a Plate Waveguide Sensor
Energy Technology Data Exchange (ETDEWEB)
Bae, Jin Ho; Joo, Young Sang; Kim, Jong Bum [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Rhee, Hui Nam [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2010-05-15
As the sodium coolant of a sodium-cooled fast reactor (SFR) is opaque to light, a conventional visual inspection cannot be used for carrying out an in-service inspection of the internal structures under a sodium level. An ultrasonic wave should be applied for an under-sodium viewing of the internal structures in a reactor vessel. Immersion sensors and waveguide sensors have been applied to the under-sodium visualization. The immersion sensor has a precise imaging capability, but may have high temperature restrictions and an uncertain life. The waveguide sensor has the advantages of a long lifetime and stable application. Recently, a new plate waveguide sensor has been developed for the versatile applications in the under-sodium viewing application. In the plate waveguide sensor, the A0 leaky Lamb wave is utilized for the long distance propagation and the effective radiation capability in a fluid. And a new technique is presented which is capable of steering an ultrasonic beam of a waveguide sensor without a mechanical movement of the sensor assembly. In this paper, the experimental study of the radiation beam profile of the A0 leaky Lamb wave in a plate waveguide sensor is carried out
Time-resolved terahertz spectroscopy in a parallel-plate waveguide
DEFF Research Database (Denmark)
Cooke, David; Jepsen, Peter Uhd
2009-01-01
The parallel plate waveguide (PPWG), formed by two conducting parallel plates separated by a distance on the order of the wavelength of the propagating light, has shown itself to be a near ideal terahertz interconnect exhibiting low loss and dispersionless propagation.[1] It is also a useful tool...... by the spatial distribution of injected charge carriers. We further discuss the possibility of using patterned excitation to control THz propagation inside the waveguide, such as creating a 2D mirror with a line excitation.......The parallel plate waveguide (PPWG), formed by two conducting parallel plates separated by a distance on the order of the wavelength of the propagating light, has shown itself to be a near ideal terahertz interconnect exhibiting low loss and dispersionless propagation.[1] It is also a useful tool...... demonstrate such a technique for time-resolved optical pump-THz probe measurements of materials embedded within a parallel plate waveguide. This is made possible by replacing one of the plates with a transparent conducting oxide, which provides sufcient electrical conductivity to guide the THz pulse, yet...
Spring-forward in composite plate elements
Wijskamp, Sebastiaan; Lamers, E.A.D.; Akkerman, Remko; Banabic, D.
2005-01-01
Spring-forward is a distortion of corner sections in continuous fibre reinforced composite products. The linear thermoelastic prediction for the spring-forward of single curved geometries is incorporated in a FE formulation for plate elements in order to simulate the spring-forward of doubly curved
Spring-forward in composite plate elements
Wijskamp, S.; Lamers, E.A.D.; Akkerman, R.
2005-01-01
Spring-forward is a distortion of corner sections in continuous fibre reinforced composite products. The linear thermoelastic prediction for the spring-forward of single curved geometries is incorporated in a FE formulation for plate elements in order to simulate the spring-forward of doubly curved
Energy Technology Data Exchange (ETDEWEB)
Zhao Ding; Ding Yaogen [Key Laboratory of High Power Microwave Sources and Technologies, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190 (China)
2011-09-15
A dielectric loaded parallel plate waveguide sheet electron beam system can be taken as a reliable model for the practical dielectric loaded rectangular waveguide sheet beam system that has a transverse cross section with a large width to height ratio. By using kinetic theory, the dispersion equations for Cerenkov and cyclotron Cerenkov instabilities in the parallel plate waveguide sheet beam system have been obtained rigorously. The dependences of the growth rate of both instabilities on the electric and structural parameters have also been investigated in detail through numerical calculations. It is worthwhile to point out that adopting an electron beam with transverse velocity can evidently improve the growth rate of Cerenkov instability, which seems like the case of cyclotron Cerenkov instability.
Intra Plate Stresses Using Finite Element Modelling
Directory of Open Access Journals (Sweden)
Jayalakshmi S.
2016-10-01
Full Text Available One of the most challenging problems in the estimation of seismic hazard is the ability to quantify seismic activity. Empirical models based on the available earthquake catalogue are often used to obtain activity of source regions. The major limitation with this approach is the lack of sufficient data near a specified source. The non-availability of data poses difficulties in obtaining distribution of earthquakes with large return periods. Such events recur over geological time scales during which tectonic processes, including mantle convection, formation of faults and new plate boundaries, are likely to take place. The availability of geometries of plate boundaries, plate driving forces, lithospheric stress field and GPS measurements has provided numerous insights on the mechanics of tectonic plates. In this article, a 2D finite element model of Indo-Australian plate is developed with the focus of representing seismic activity in India. The effect of large scale geological features including sedimentary basins, fold belts and cratons on the stress field in India is explored in this study. In order to address long term behaviour, the orientation of stress field and tectonic faults of the present Indo-Australian plate are compared with a reconstructed stress field from the early Miocene (20 Ma.
CSIR Research Space (South Africa)
Loveday, PW
2007-03-01
Full Text Available conventional finite element methods available in commercial software, these models tend to be very large. An alternative method is to use specially formulated waveguide finite elements (sometimes called Semi-Analytical Finite Elements). Models using...
Non-invasive method of field imaging in parallel plate waveguides
DEFF Research Database (Denmark)
Iwaszczuk, Krzysztof; Andryieuski, Andrei; Lavrinenko, Andrei
2011-01-01
We present a new non-invasive air-photonic-based method of terahertz (THz) field imaging inside a parallel plate waveguide. The method is based on THz field-enhanced second harmonic generation of the fundamental laser beam in an external electric field. We also demonstrate the direct measurements...
Waveguide Invariant and Passive Ranging Using Double Element
Institute of Scientific and Technical Information of China (English)
余赟; 惠俊英; 陈阳; 林芳
2011-01-01
The sea-trial results indicate that the stable interference structure can be observed in low-frequency continuous spectra sound field. And the equation of the interference striation have been derived in light of the comcept of waveguide in- variant, indicating that the striations are a family of quasi hyperbolas. The heading angle φ, waveguide invariant β and r0 v（ro is the range of the closest point of approach and v is the navigating velocity of target） are estimated by using Hough transform for the image processing of the LOFARgram and bearing-time records. Four passive ranging algorithms based on double element or double array model are proposed. The simulation research shows that the first positioning algorithm should be adopted when the target heading angle is less than 10~; otherwise, the latter three algorithms are used to range, and the larger the heading angle is, the higher the positioning accuracy is. The relative ranging errors of the four methods are less than 10% under the simulation conditions used in this paper.
Directory of Open Access Journals (Sweden)
Xiao-Peng Wang
2015-10-01
Full Text Available In this paper, the tuning characteristics of band gaps and waveguides in a locally resonant phononic crystal structure, consisting of multiple square stubs deposited on a thin homogeneous plate, are investigated. Using the finite element method and supercell technique, the dispersion relationships and power transmission spectra of those structures are calculated. In contrast to a system of one square stub, systems of multiple square stubs show wide band gaps at lower frequencies and an increased quantity of band gaps at higher frequencies. The vibration modes of the band gap edges are analyzed to clarify the mechanism of the generation of the lowest band gap. Additionally, the influence of the stubs arrangement on the band gaps in multi-stub systems is investigated. The arrangements of the stubs were found to influence the band gaps; this is critical to understand for practical applications. Based on this finding, a novel method to form defect scatterers by changing the arrangement of square stubs in a multi-stub perfect phononic crystal plate was developed. Defect bands can be induced by creating defects inside the original complete band gaps. The frequency can then be tuned by changing the defect scatterers’ stub arrangement. These results will help in fabricating devices such as acoustic filters and waveguides whose band frequency can be modulated.
Time Reversal Self-Focusing in a Solid-Plate Waveguide
Institute of Scientific and Technical Information of China (English)
ZHANG Bi-Xing; WU Hao; WANG Cheng-Hao
2004-01-01
@@ Acoustic self-adaptive focusing in a solid-plate waveguide is theoretically and experimentally studied. The multipath effect exists in the solid plate. A pulse will be widened into a pulsed train and the waveform is distorted. The time-reversal mirrors are applied to study the self-adaptive focusing. The time-reversal effect can be characterized by the focusing gain and the ratio of the principal to the second lobe. It is found theoretically and experimentally that the time-reversal mirrors can compensate automatically for the waveform distortion caused by the multi-path effect.
A NEW QUADRILATERAL THIN PLATE ELEMENT BASED ON THE MEMBRANE-PLATE SIMILARITY THEORY
Institute of Scientific and Technical Information of China (English)
黄若煜; 郑长良; 钟万勰; 姚伟岸
2002-01-01
A new effective path has been proposed to formulate thin plate element by using the similarity theory between plane elasticity and plate bending. Because of avoiding the difficulty of c1 continuity , the construction of thin plate elements becomes easier. The similarity theory and its applications were discussed more deeply, and a new four nodes, sixteen D. O. F. ( degree of fieedom) thin plate element was presented on the base of the similarity theory. Numerical results for typical problems show that this new element can pass the patch test and has a very good convergence and a high precision.
Fourier finite element modeling of light emission in waveguides: 2.5-dimensional FEM approach.
Ou, Yangxin; Pardo, David; Chen, Yuntian
2015-11-16
We present a Fourier finite element modeling of light emission of dipolar emitters coupled to infinitely long waveguides. Due to the translational symmetry, the three-dimensional (3D) coupled waveguide-emitter system can be decomposed into a series of independent 2D problems (2.5D), which reduces the computational cost. Moreover, the reduced 2D problems can be extremely accurate, compared to its 3D counterpart. Our method can precisely quantify the total emission rates, as well as the fraction of emission rates into different modal channels for waveguides with arbitrary cross-sections. We compare our method with dyadic Green's function for the light emission in single mode metallic nanowire, which yields an excellent agreement. This method is applied in multi-mode waveguides, as well as multi-core waveguides. We further show that our method has the full capability of including dipole orientations, as illustrated via a rotating dipole, which leads to unidirectional excitation of guide modes. The 2.5D Finite Element Method (FEM) approach proposed here can be applied for various waveguides, thus it is useful to interface single-photon single-emitter in nano-structures, as well as for other scenarios involving coupled waveguide-emitters.
Vibration Analysis of Plates by MLS-Element Method
Zhou, L.; Xiang, Y.
2010-05-01
This paper presents a novel numerical method, the moving least square element (MLS-element) method for the free vibration analysis of plates based on the Mindlin shear deformable plate theory. In the MLS-element method, a plate can be first divided into multiple elements which are connected through selected nodal points on the interfaces of the elements. An element can be of any shape and the size of the element varies dependent on the problem at hand. The shape functions of the element for the transverse displacement and the rotations are derived based on the MLS interpolation technique. The convergence and accuracy of the method can be controlled by either increasing the number of elements or by increasing the number of MLS interpolation points within elements. Two selected examples for vibration of a simply supported square Mindlin plate and a clamped L-shaped Mindlin plate are studied to illustrate the versatility and accuracy of the proposed method. It shows that the proposed method is highly accurate and flexible for the vibration analysis of plate problems. The method can be further developed to bridge the existing meshless method and the powerful finite element method in dealing with various engineering computational problems, such as large deformation and crack propagation in solid mechanics.
Finite element method for accurate 3D simulation of plasmonic waveguides
Burger, S; Pomplun, J; Schmidt, F; 10.1117/12.841995
2010-01-01
Optical properties of hybrid plasmonic waveguides and of low-Q cavities, formed by waveguides of finite length are investigated numerically. These structures are of interest as building-blocks of plasmon lasers. We use a time-harmonic finite-element package including a propagation-mode solver, a resonance-mode solver and a scattering solver for studying various properties of the system. Numerical convergence of all used methods is demonstrated.
Thermal Analysis of Thin Plates Using the Finite Element Method
Er, G. K.; Iu, V. P.; Liu, X. L.
2010-05-01
The isotropic thermal plate is analyzed with finite element method. The solution procedure is presented. The elementary stiffness matrix and loading vector are derived rigorously with variation principle and the principle of minimum potential energy. Numerical results are obtained based on the derived equations and tested with available exact solutions. The problems in the finite element analysis are figured out. It is found that the finite element solutions can not converge as the number of elements increases around the corners of the plate. The derived equations presented in this paper are fundamental for our further study on more complicated thermal plate analysis.
New triangular and quadrilateral plate-bending finite elements
Narayanaswami, R.
1974-01-01
A nonconforming plate-bending finite element of triangular shape and associated quadrilateral elements are developed. The transverse displacement is approximated within the element by a quintic polynomial. The formulation takes into account the effects of transverse shear deformation. Results of the static and dynamic analysis of a square plate, with edges simply supported or clamped, are compared with exact solutions. Good accuracy is obtained in all calculations.
Energy Technology Data Exchange (ETDEWEB)
Bae, Jin Ho; Joo, Young Sang; Ham, Ji Woong; Kim, Jong Bum [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2012-05-15
In-vessel structures of a sodium-cooled fast reactor (SFR) are submerged in opaque liquid sodium in the reactor vessel. The ultrasonic inspection techniques should be applied for observing the in-vessel structures under hot liquid sodium. Ultrasonic sensors such as immersion sensors and rod-type waveguide sensors have developed in order to apply under-sodium viewing of the in-vessel structures of SFR. Recently the novel plate-type ultrasonic waveguide sensor has been developed for the versatile application of under-sodium viewing in SFR. In previous studies, to improve the performance of the ultrasonic waveguide sensor module in the under-sodium application, the dispersion effect due to the 10 m long distance propagation of the A0-mode Lamb wave should be minimized and the longitudinal leaky wave in liquid sodium should be generated within the range of the effective radiation angle. A new concept of ultrasonic waveguide sensors with a layered-structured plate is suggested for the non-dispersive propagation of A0-mode Lamb wave in an ultrasonic waveguide sensor and the effective generation of a leaky wave in liquid sodium. In this work, the propagation and radiation of the leaky Lamb wave in the waveguide sensor coated with Beryllium has been performed by FEM simulations
ACCURACY ANALYSIS OF 12-PARAMETERRECTANGULAR PLATE ELEMENTS WITH GEOMETRIC SYMMETRY
Institute of Scientific and Technical Information of China (English)
SHI Dongyang; CHEN Shaochun
2000-01-01
In this paper, it is proved that the double set parameter rectangular plate elements with geometric symmetry possess a very special convergence property, i.e., the consistency error due to nonconformity is of order O(h2) which is one order higher than that of ACM element and rectangular generalized conforming element proposed by Y. Q.Long, although all these elements have the same asympotical rate of convergence O(h)in the energy norm. This particular property seems to be never seen before for other nonconforming rectangular plate elements.
A mixed finite element for the analysis of laminated plates
Putcha, N. S.; Reddy, J. N.
1983-01-01
A new mixed shear-flexible finite element based on the Hellinger-Reissner's variational principle is developed. The element is constructed using a mixed formulation of the shear deformation theory of laminated composite plates, and consists of three displacements, two shear rotations, and three moments as the independent degrees of freedom. The numerical convergence and accuracy characteristics of the element are investigated for bending of laminated anisotropic composite plates. The element is relatively simple to construct and has better accuracy and convergence features when compared to other conventional finite elements.
Finite Element Analysis of Circular Plate using SolidWorks
Energy Technology Data Exchange (ETDEWEB)
Kang, Yeo Jin; Jhung, Myung Jo [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)
2011-10-15
Circular plates are used extensively in mechanical engineering for nuclear reactor internal components. The examples in the reactor vessel internals are upper guide structure support plate, fuel alignment plate, lower support plate etc. To verify the structural integrity of these plates, the finite element analyses are performed, which require the development of the finite element model. Sometimes it is very costly and time consuming to make the model especially for the beginners who start their engineering job for the structural analysis, necessitating a simple method to develop the finite element model for the pursuing structural analysis. Therefore in this study, the input decks are generated for the finite element analysis of a circular plate as shown in Fig. 1, which can be used for the structural analysis such as modal analysis, response spectrum analysis, stress analysis, etc using the commercial program Solid Works. The example problems are solved and the results are included for analysts to perform easily the finite element analysis of the mechanical plate components due to various loadings. The various results presented in this study would be helpful not only for the benchmark calculations and results comparisons but also as a part of the knowledge management for the future generation of young designers, scientists and computer analysts
Calculations of circular waveguide with a rectangular metal insert.
Directory of Open Access Journals (Sweden)
Yu. K. Sydoruk
2010-05-01
Full Text Available Calculated and analyzed the basic parameters of electromagnetic wave in a circular waveguide with a rectangular metal plate in the following cases: when the circular waveguide without metal plate for a H11 wave of subcritical, critical and supercritical. For calculations was used a finite element method and Ansoft HFSS program.
Finite Element Analysis of Reinforced Concrete Plate Impacted by Block
Institute of Scientific and Technical Information of China (English)
LUO Xiaoyang; Pascal PERROTIN; YAN Quansheng
2006-01-01
A new concept of structurally dissipating rock-shed (SDR) was developed by the lab of Tonello IC and LOCIE-ESIGEC (France).To decide the dimension of the plate used in SDR,an ANSYS model which could simulate the impact of rock in the centre of the plate was established by Fabien Delhomme.By using this model,some finite element analyses are carried out in the present paper Firstly,a plate impacted by a block is numerically simulated,the numerical results obtained from different mesh sizes are compared and the accuracy of the finite element model is verified.Then,the dynamic response of the plate impacted at the boundary and in the medium part is computed.By analyzing the stress in rebar,the most dangerous region of impact of plate was found.For a rectangular plate,the most dangerous region is at the corner of the plate when a block drops in.Finally,the whole deformation process of the plate under dropping block was simulated and a simplified definition (effect zone) to describe the deformation process in different positions of plate was given.From this study,it is found that the impact only affects heavily within the effect zone.
Xia, Yi-Ming
2015-01-01
A locking-free rectangular Mindlin plate element with a new multi-resolution analysis (MRA) is proposed and a multireolution finite element method is hence presented. The MRA framework is formulated out of a mutually nesting displacement subspace sequence. The MRA endows the proposed element with the resolution level (RL) to adjust the element node number, thus modulating structural analysis accuracy accordingly. As a result, the traditional 4-node rectangular Mindlin plate element and method is a mono-resolution one and also a special case of the proposed element and method. The meshing for the monoresolution plate element model is based on the empiricism while the RL adjusting for the multiresolution is laid on the rigorous mathematical basis. The accuracy of a structural analysis is actually determined by the RL, not by the mesh. The rational MRA enables the implementation of the multiresolution Mindlin plate element method to be more rational and efficient than that of the conventional monoresolution or o...
Finite Element Vibration Analysis of Beams, Plates and Shells
Directory of Open Access Journals (Sweden)
Jaroslav Mackerle
1999-01-01
Full Text Available This bibliography lists references to papers, conference proceedings and theses/dissertations dealing with finite element vibration analysis of beams, plates and shells that were published in 1994–1998. It contains 361 citations. Also included, as separated subsections, are vibration analysis of composite materials and vibration analysis of structural elements with cracks/contacts.
A COMBINED HYBRID FINITE ELEMENT METHOD FOR PLATE BENDING PROBLEMS
Institute of Scientific and Technical Information of China (English)
Tian-xiao Zhou; Xiao-ping Xie
2003-01-01
In this paper, a combined hybrid method is applied to finite element discretization ofplate bending problems. It is shown that the resultant schemes are stabilized, i.e., theconvergence of the schemes is independent of inf-sup conditions and any other patch test.Based on this, two new series of plate elements are proposed.
The first ANDES elements: 9-DOF plate bending triangles
Militello, Carmelo; Felippa, Carlos A.
1991-01-01
New elements are derived to validate and assess the assumed natural deviatoric strain (ANDES) formulation. This is a brand new variant of the assumed natural strain (ANS) formulation of finite elements, which has recently attracted attention as an effective method for constructing high-performance elements for linear and nonlinear analysis. The ANDES formulation is based on an extended parametrized variational principle developed in recent publications. The key concept is that only the deviatoric part of the strains is assumed over the element whereas the mean strain part is discarded in favor of a constant stress assumption. Unlike conventional ANS elements, ANDES elements satisfy the individual element test (a stringent form of the patch test) a priori while retaining the favorable distortion-insensitivity properties of ANS elements. The first application of this formulation is the development of several Kirchhoff plate bending triangular elements with the standard nine degrees of freedom. Linear curvature variations are sampled along the three sides with the corners as gage reading points. These sample values are interpolated over the triangle using three schemes. Two schemes merge back to conventional ANS elements, one being identical to the Discrete Kirchhoff Triangle (DKT), whereas the third one produces two new ANDES elements. Numerical experiments indicate that one of the ANDES element is relatively insensitive to distortion compared to previously derived high-performance plate-bending elements, while retaining accuracy for nondistorted elements.
Higher-order hybrid stress triangular Mindlin plate element
Li, Tan; Ma, Xu; Xili, Jing; Chen, Wanji
2016-12-01
A 6-node triangular hybrid stress element is presented for Mindlin plate in this paper. The proposed element, denoted by TH6-27β, can pass both the zero shear stress patch test and the non-zero constant shear stress enhanced patch test and, it can be employed to analyze very thin plate. To accomplish this purpose, special attention is devoted to selecting boundary displacement interpolation and stress approximation in domain. The arbitrary order Timoshenko beam function is used successfully to derive the displacement interpolation along each side of the element. According to the equilibrium equations, an appropriate stress approximation is rationally obtained. The assumed stress field is modified by using 27β instead of 15β to improve the accuracy. Numerical results show that the element is free of shear locking, and reliable for thick and thin plates. Moreover, it has no spurious zero energy modes and with geometric invariance (coordinate invariance, node sequencing independence).
Fourier finite element modeling of light emission in waveguides: 2.5-dimensional FEM approach
Ou, Yangxin; Chen, Yuntian
2015-01-01
We present a Fourier finite element modeling of light emission of dipolar emitters coupled to infinitely long waveguides. Due to the translational symmetry, the three-dimensional (3D) coupled waveguide-emitter system can be decomposed into a series of independent 2D problems (2.5D), which reduces the computational cost. Moreover, the reduced 2D problems can be extremely accurate, compared to its 3D counterpart. Our method can precisely quantify the total emission rates, as well as the fraction of emission rates into different modal channels for waveguides with arbitrary cross-sections. We compare our method with dyadic Green's function for the light emission in single mode metallic nanowire, which yields an excellent agreement. This method is applied in multi-mode waveguides, as well as multi-core waveguides. We further show that our method has the full capability of including dipole orientations, as illustrated via a rotating dipole, which leads to unidirectional excitation of guide modes. The 2.5D Finite El...
A new multiresolution finite element method based on a multiresolution quadrilateral plate element
Xia, YiMing
2014-01-01
A new multiresolution quadrilateral plate element is proposed and a multiresolution finite element method is hence presented. The multiresolution analysis (MRA) framework is formulated out of a mutually nesting displacement subspace sequence, whose basis functions are constructed of scaling and shifting on the element domain of basic node shape function. The basic node shape function is constructed by extending shape function around a specific node. The MRA endows the proposed element with the resolution level (RL) to adjust the element node number, thus modulating structural analysis accuracy accordingly. As a result, the traditional 4-node quadrilateral plate element and method is a monoresolution one and also a special case of the proposed element and method. The meshing for the monoresolution plate element model is based on the empiricism while the RL adjusting for the multiresolution is laid on the rigorous mathematical basis. The accuracy of a structural analysis is fully determined by the RL, not by th...
A lumped mass finite element method for vibration analysis of elastic plate-plate structures
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
The fully discrete lumped mass finite element method is proposed for vibration analysis of elastic plate-plate structures.In the space directions,the longitudinal displacements on plates are discretized by conforming linear elements,and the transverse displacements are discretized by the Morley element.By means of the second order central difference for discretizing the time derivative and the technique of lumped masses,a fully discrete lumped mass finite element method is obtained,and two approaches to choosing the initial functions are also introduced.The error analysis for the method in the energy norm is established,and some numerical examples are included to validate the theoretical analysis.
A new strain based brick element for plate bending
Directory of Open Access Journals (Sweden)
L. Belounar
2014-03-01
Full Text Available This paper presents the development of a new three-dimensional brick finite element by the use of the strain based approach for the linear analysis of plate bending. The developed element has the three essential external degrees of freedom (U, V and W at each of the eight corner nodes as well as at the centroidal node. The displacement field of the developed element is based on assumed functions for the various strains satisfying the compatibility equations and the static condensation technique is used for the internal node. The performance of this element is evaluated on several problems related to thick and thin plate bending in linear analysis. The obtained results show the good performances and accuracy of the present element.
SPLITTING MODULUS FINITE ELEMENT METHOD FOR ORTHOGONAL ANISOTROPIC PLATE BENGING
Institute of Scientific and Technical Information of China (English)
党发宁; 荣廷玉; 孙训方
2001-01-01
Splitting modulus variational principle in linear theory of solid mechanics was introduced, the principle for thin plate was derived, and splitting modulus finite element method of thin plate was established too. The distinctive feature of the splitting model is that its functional contains one or more arbitrary additional parameters, called splitting factors,so stiffness of the model can be adjusted by properly selecting the splitting factors. Examples show that splitting modulus method has high precision and the ability to conquer some illconditioned problems in usual finite elements. The cause why the new method could transform the ill-conditioned problems into well-conditioned problem, is analyzed finally.
FINITE ELEMENT MODELING OF THIN CIRCULAR SANDWICH PLATES DEFLECTION
Directory of Open Access Journals (Sweden)
K. S. Kurachka
2014-01-01
Full Text Available A mathematical model of a thin circular sandwich plate being under the vertical load is proposed. The model employs the finite element method and takes advantage of an axisymmetric finite element that leads to the small dimension of the resulting stiffness matrix and sufficient accuracy for practical calculations. The analytical expressions for computing local stiffness matrices are found, which can significantly speed up the process of forming the global stiffness matrix and increase the accuracy of calculations. A software is under development and verification. The discrepancy between the results of the mathematical model and those of analytical formulas for homogeneous thin circularsandwich plates does not exceed 7%.
Narayanaswami, R.
1973-01-01
A new higher order triangular plate-bending finite element is presented which possesses high accuracy for practical mesh subdivisions and which uses only translations and rotations as grid point degrees of freedom. The element has 18 degrees of freedom, the transverse displacement and two rotations at the vertices and mid-side grid points of the triangle. The transverse displacement within the element is approximated by a quintic polynomial; the bending strains thus vary cubically within the element. Transverse shear flexibility is taken into account in the stiffness formulation. Two examples of static and dynamic analysis are included to show the behavior of the element.
TRAPEZOIDAL PLATE BENDING ELEMENT WITH DOUBLE SET PARAMETERS
Institute of Scientific and Technical Information of China (English)
Shao-chun Chen; Dong-yang Shi; I chiro Hagiwara
2003-01-01
Using double set parameter method, a 12-parameter trapezoidal plate bending element is presented. The first set of degrees of freedom, which make the element convergent, are the values at the four vertices and the middle points of the four sides together with the mean values of the outer normal derivatives along four sides. The second set of degree of freedom, which make the number of unknowns in the resulting discrete system small and computation convenient are values and the first derivatives at the four vertices of the element. The convergence of the element is proved.
Casimir, J. B.; Kevorkian, S.; Vinh, T.
2005-10-01
This paper describes a procedure for building the dynamic stiffness matrix of two-dimensional elements with free edge boundary conditions. The dynamic stiffness matrix is the basis of the continuous element method. Then, the formulation is used to build a Kirchhoff rectangular plate element. Gorman's method of boundary condition decomposition and Levy's series are used to obtain the strong solution of the elementary problem. A symbolic computation software partially performs the construction of the dynamic stiffness matrix from this solution. The performances of the element are evaluated from comparisons with harmonic responses of plates obtained by the finite element method.
2016-01-01
A metallic hollow waveguide is promising fiber for the delivery of laser radiation. Thickness of the nickel plated layer for supporting of the waveguide in fabrication of a dielectric coated silver hollow nickel waveguide is very important factor. In this paper, the change characteristic in the thickness of the nickel plated layer along the length of the silver coated glass mandrel during fabricating the silver hollow nickel waveguide by the outer-coating method of the liquid phase process ha...
Novel boundary element method for resolving plate bending problems
Institute of Scientific and Technical Information of China (English)
陈颂英; 王乐勤; 焦磊
2003-01-01
This paper discusses the application of the boundary contour method for resolving plate bending problems. The exploitation of the integrand divergence free property of the plate bending boundary integral equation based on the Kirchhoff hypothesis and a very useful application of Stokes' Theorem are presented to convert surface integrals on boundary elements to the computation of bending potential functions on the discretized boundary points, even for curved surface elements of arbitrary shape. Singularity and treatment of the discontinued corner point are not needed at all. The evaluation of the physics variant at internal points is also shown in this article. Numerical results are presented for some plate bending problems and compared against analytical and previous solutions.
Ro, Sok-Bong; Kim, Uo-Hyon
2016-01-01
A metallic hollow waveguide is promising fiber for the delivery of laser radiation. Thickness of the nickel plated layer for supporting of the waveguide in fabrication of a dielectric coated silver hollow nickel waveguide is very important factor. In this paper, the change characteristic in the thickness of the nickel plated layer along the length of the silver coated glass mandrel during fabricating the silver hollow nickel waveguide by the outer-coating method of the liquid phase process has been studied both experimentally and analytically. Waveguides with uniform thickness of the nickel plated layer along the length of the silver coated glass mandrel have been fabricated.
A Novel Rectangular Element for Piezoelectric Laminated Plates
Institute of Scientific and Technical Information of China (English)
ZHOU Yong; WANG Xing-wei; SUN Ya-fei
2004-01-01
Based on the classical laminated plate theory, a novel finite element formulation is presented for modeling the static response of laminated composites containing distributed piezoelectric ceramic subjected to electric loadings. A four-node rectangular composite element with an additional voltage freedom per piezoelectric layer is implemented for the analysis. The element can predict more accurately the bending response of the structure because of its new displacement radixes. Numerical examples ere performed and the calculated data compare very well with existing results in the literatures.
Uranium density reduction on fuel element side plates assessment
Energy Technology Data Exchange (ETDEWEB)
Rios, Ilka A. [Centro Tecnologico da Marinha em Sao Paulo (CTMSP), Sao Paulo, SP (Brazil); Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Andrade, Delvonei A.; Domingos, Douglas B.; Umbehaun, Pedro E. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)
2011-07-01
During operation of IEA-R1 research reactor, located at Instituto de Pesquisas Energeticas e Nucleares, IPEN - CNEN/SP, an abnormal oxidation on some fuel elements was noted. It was also verified, among the possible causes of the problem, that the most likely one was insufficient cooling of the elements in the core. One of the propositions to solve or minimize the problem is to reduce uranium density on fuel elements side plates. In this paper, the influence of this change on neutronic and thermal hydraulic parameters for IEA-R1 reactor is verified by simulations with the codes HAMMER and CITATION. Results are presented and discussed. (author)
Haddouche, Issam; Cherbi, Lynda
2017-01-01
In this paper, we investigate Surface Plasmon Polaritons (SPPs) in the visible regime at a metal/dielectric interface within two different waveguide structures, the first is a Photonic Crystal Fiber where the Full Vector Finite Element Method (FVFEM) is used and the second is a slab waveguide where the transfer matrix method (TMM) is used. Knowing the diversities between the two methods in terms of speed, simplicity, and scope of application, computation is implemented with respect to wavelength and metal layer thickness in order to analyze and compare the performances of the two methods. Simulation results show that the TMM can be a good approximation for the FVFEM and that SPPs behave more like modes propagating in a semi infinite metal/dielectric structure as metal thickness increases from about 150 nm.
Stochastic Finite Element Analysis of Plate and Shell Construction
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
The response of random plate and shell construction is analyzed with the stochastic finite element method (SFEM). Random material properties and geometric dimensions of construction are involved in this paper. A simplified isoparametric local average model is used to describe the random field. Numerical results of the examples indicate that the approach presented herein is an economical and efficient solution for such an analysis compared with Monte Carlo simulation (MCS).
Institute of Scientific and Technical Information of China (English)
Dong Jianfeng; Xu Shanjia
2006-01-01
The reflection and transmission characteristics of the guided modes in parallel-plate waveguides partially filled with one or multi chiral rods have been investigated by a method, which combines the multimode network theory with a rigorous mode matching procedure. The formulas of the reflection and transmission coefficient matrix are derived. The numerical results for different cases are presented and have indicated that the chirality parameters and the geometrical dimensions of the chiral rods have significant influence on the reflection and transmission characteristics of the guided modes.
Multi-Step Ka/Ka Dichroic Plate with Rounded Corners for NASA's 34m Beam Waveguide Antenna
Veruttipong, Watt; Khayatian, Behrouz; Hoppe, Daniel; Long, Ezra
2013-01-01
A multi-step Ka/Ka dichroic plate Frequency Selective Surface (FSS structure) is designed, manufactured and tested for use in NASA's Deep Space Network (DSN) 34m Beam Waveguide (BWG) antennas. The proposed design allows ease of manufacturing and ability to handle the increased transmit power (reflected off the FSS) of the DSN BWG antennas from 20kW to 100 kW. The dichroic is designed using HFSS and results agree well with measured data considering the manufacturing tolerances that could be achieved on the dichroic.
Multi-Step Ka/Ka Dichroic Plate with Rounded Corners for NASA's 34m Beam Waveguide Antenna
Veruttipong, Watt; Khayatian, Behrouz; Hoppe, Daniel; Long, Ezra
2013-01-01
A multi-step Ka/Ka dichroic plate Frequency Selective Surface (FSS structure) is designed, manufactured and tested for use in NASA's Deep Space Network (DSN) 34m Beam Waveguide (BWG) antennas. The proposed design allows ease of manufacturing and ability to handle the increased transmit power (reflected off the FSS) of the DSN BWG antennas from 20kW to 100 kW. The dichroic is designed using HFSS and results agree well with measured data considering the manufacturing tolerances that could be achieved on the dichroic.
An electromechanical finite element model for piezoelectric energy harvester plates
De Marqui Junior, Carlos; Erturk, Alper; Inman, Daniel J.
2009-10-01
Vibration-based energy harvesting has been investigated by several researchers over the last decade. The goal in this research field is to power small electronic components by converting the waste vibration energy available in their environment into electrical energy. Recent literature shows that piezoelectric transduction has received the most attention for vibration-to-electricity conversion. In practice, cantilevered beams and plates with piezoceramic layers are employed as piezoelectric energy harvesters. The existing piezoelectric energy harvester models are beam-type lumped parameter, approximate distributed parameter and analytical distributed parameter solutions. However, aspect ratios of piezoelectric energy harvesters in several cases are plate-like and predicting the power output to general (symmetric and asymmetric) excitations requires a plate-type formulation which has not been covered in the energy harvesting literature. In this paper, an electromechanically coupled finite element (FE) plate model is presented for predicting the electrical power output of piezoelectric energy harvester plates. Generalized Hamilton's principle for electroelastic bodies is reviewed and the FE model is derived based on the Kirchhoff plate assumptions as typical piezoelectric energy harvesters are thin structures. Presence of conductive electrodes is taken into account in the FE model. The predictions of the FE model are verified against the analytical solution for a unimorph cantilever and then against the experimental and analytical results of a bimorph cantilever with a tip mass reported in the literature. Finally, an optimization problem is solved where the aluminum wing spar of an unmanned air vehicle (UAV) is modified to obtain a generator spar by embedding piezoceramics for the maximum electrical power without exceeding a prescribed mass addition limit.
Finite element model calibration of a nonlinear perforated plate
Ehrhardt, David A.; Allen, Matthew S.; Beberniss, Timothy J.; Neild, Simon A.
2017-03-01
This paper presents a case study in which the finite element model for a curved circular plate is calibrated to reproduce both the linear and nonlinear dynamic response measured from two nominally identical samples. The linear dynamic response is described with the linear natural frequencies and mode shapes identified with a roving hammer test. Due to the uncertainty in the stiffness characteristics from the manufactured perforations, the linear natural frequencies are used to update the effective modulus of elasticity of the full order finite element model (FEM). The nonlinear dynamic response is described with nonlinear normal modes (NNMs) measured using force appropriation and high speed 3D digital image correlation (3D-DIC). The measured NNMs are used to update the boundary conditions of the full order FEM through comparison with NNMs calculated from a nonlinear reduced order model (NLROM). This comparison revealed that the nonlinear behavior could not be captured without accounting for the small curvature of the plate from manufacturing as confirmed in literature. So, 3D-DIC was also used to identify the initial static curvature of each plate and the resulting curvature was included in the full order FEM. The updated models are then used to understand how the stress distribution changes at large response amplitudes providing a possible explanation of failures observed during testing.
DEFF Research Database (Denmark)
Jin, Yabin; Fernez, Nicolas; Pennec, Yan;
2016-01-01
We investigate the properties of a phononic crystal plate with hollow pillars and introduce the existence of whispering-gallery modes (WGMs). We show that by tuning the inner radius of the hollow pillar, these modes can merge inside both Bragg and low frequency band gaps, deserving phononic crystal...... and acoustic metamaterial applications. These modes can be used as narrow pass bands for which the quality factor can be greatly enhanced by the introduction of an additional cylinder between the hollow cylinder and the plate. We discuss some functionalities of these confined WGM in both Bragg and low...... frequency gaps for wavelength division in multiplexer devices using heteroradii pillars introduced into waveguide and cavity structures....
Chattopadhyay, G.; Llombart, N.; Bradford, C.M.; Neto, A.
2008-01-01
Micromesh bolometers have been used in several instruments working in the submillimeter band (e.g. [1]). The bolometers are usually placed inside a waveguide and consist of a mesh absorber, at a certain distance from a back short. The mesh is made of SiNi whose thermal conductivity is tuned to the i
A Jacobian Separable 2-D Finite-Element Method for Electromagnetic Waveguide Problems
Khodapanah, Ehsan
2016-01-01
We propose an efficient finite-element analysis of the vector wave equation in a class of relatively general curved polygons. The proposed method is suitable for an accurate and efficient calculation of the propagation constants of waveguides filled with pieces of homogeneous materials. To apply the method, we first decompose the 2-D problem domain into a set of curved polygons of a specific characteristic. Then we divide every polygon into a set of triangular elements with two straight edges. Finally, we introduce a set of hierarchical mixed-order curl-conforming vector basis functions inside every triangular element to discretize the vector wave equation. The advantages of the method are as follows. The curved boundaries of the elements are modeled exactly and hence there is no approximation in the geometrical modeling. 2-D integrals of the matrix elements are reduced to 1-D integrals. Therefore, the matrix filling can be performed very fast. Total number of elements due to the discretization of a given dom...
Fuel burnup calculation of a research reactor plate element
Energy Technology Data Exchange (ETDEWEB)
Santos, Nadia Rodrigues dos; Lima, Zelmo Rodrigues de; Moreira, Maria de Lourdes, E-mail: nadiasam@gmail.com, E-mail: zrlima@ien.gov.br, E-mail: malu@ien.gov.br [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)
2013-07-01
This work consists in simulating the burnup of two different plate type fuel elements, where one is the benchmark MTR of the IAEA, which is made of an alloy of uranium and aluminum, while the other belonging to a typical multipurpose reactor is composed of an alloy of uranium and silicon. The simulation is performed using the WIMSD-5B computer code, which makes use of deterministic methods for solving neutron transport. In developing this task, fuel element equivalent cells were calculated representing each of the reactors to obtain the initial concentrations of each isotope constituent element of the fuel cell and the thicknesses corresponding to each region of the cell, since this information is part of the input data. The compared values of the k∞ showed a similar behavior for the case of the MTR calculated with the WIMSD-5B and EPRI-CELL codes. Relating the graphs of the concentrations in the burnup of both reactors, there are aspects very similar to each isotope selected. The application WIMSD-5B code to calculate isotopic concentrations and burnup of the fuel element, proved to be satisfactory for the fulfillment of the objective of this work. (author)
Directory of Open Access Journals (Sweden)
Zoltán Juhász
2015-01-01
Full Text Available We analyse the buckling process of composite plates with through-the-width delamination and straight crack front applying uniaxial compression. We are focusing on the mixed mode buckling case, where the non-uniform distribution of the in-plane forces controls the occurence of the buckling of the delaminated layers. For the analysis, semi-discrete finite elements will be derived based on the Lèvy-type method. The method of harmonic balance is used for taking into account the force distribution that is generally non uniform in-plane.
A new wavelet-based thin plate element using B-spline wavelet on the interval
Jiawei, Xiang; Xuefeng, Chen; Zhengjia, He; Yinghong, Zhang
2008-01-01
By interacting and synchronizing wavelet theory in mathematics and variational principle in finite element method, a class of wavelet-based plate element is constructed. In the construction of wavelet-based plate element, the element displacement field represented by the coefficients of wavelet expansions in wavelet space is transformed into the physical degree of freedoms in finite element space via the corresponding two-dimensional C1 type transformation matrix. Then, based on the associated generalized function of potential energy of thin plate bending and vibration problems, the scaling functions of B-spline wavelet on the interval (BSWI) at different scale are employed directly to form the multi-scale finite element approximation basis so as to construct BSWI plate element via variational principle. BSWI plate element combines the accuracy of B-spline functions approximation and various wavelet-based elements for structural analysis. Some static and dynamic numerical examples are studied to demonstrate the performances of the present element.
A New Accurate Yet Simple Shear Flexible Triangular Plate Element With Linear Bending Strains
DEFF Research Database (Denmark)
Damkilde, Lars
2008-01-01
Plate bending elements have been and still are the subject of many papers. Zienkiewicz, given a very good overview of the historical development dating back to around 1965. In this paper focus will entirely be on plate elements taking the shear flexibility into account i.e. using Reissner- Mindlin...... plate theory...
Characteristics of Phase-Correcting Fresnel Zone Plates and Elliptical Waveguides
1994-02-01
Dielectric Waveguides using the Multifilament Current Model", Z. Altman, H. Cory, and Y. Leviatan , Microwave and Optical Technology Letters, Vol. 3...60; V-I10 Kudalkar, V., V-I ll Kumric, Helga, 1-32 Kuzin, E. A., V-109 Lagasse, P., 1-16 Laslett, L. J., 1-36 Lee, H. Y., 11-41 Leviatan , Y., V-102
Design Optimization of Hydraulic Press Plate using Finite Element Analysis
Directory of Open Access Journals (Sweden)
Akshay Vaishnav
2016-05-01
Full Text Available Metal forming is a process which is done by deforming metal work pieces to the desired shape and size using pressing or hammering action. Hydraulic presses are being used for forming and pressing operations with wide range of capacities. Hydraulic press machine works under continuous impact load. Because of this continuous load, tensile and compressive stresses are experienced in various parts of machine. These stresses cause permanent deformation in some parts of machine. This work is based on optimization of a 250-ton four pillar type hydraulic press considering constraints like design, weight and cost. The work is focused on design and optimization of top plate of the press machine. Top plate holds the hydraulic cylinder and is one of the most critical parts of the machine. The design is based on sizing optimization method and the results are validated by Finite Element method with proper boundary conditions. The CAD modelling has been carried out by PTC CREO and for FEA, ANSYS software is used.
NONCONFORMING QUADRILATERAL ROTATED Q1 ELEMENT FOR REISSNER-MINDLIN PLATE
Institute of Scientific and Technical Information of China (English)
Jun Hu; Pingbing Ming; Zhongci Shi
2003-01-01
In this paper, we extend two rectangular elements for Reissner-Mindlin plate [9] to thequadrilateral case. Optimal H1 and L2 error bounds independent of the plate hickness arederived under a mild assumption on the mesh partition.
Directory of Open Access Journals (Sweden)
Ding Xu
2016-08-01
Full Text Available Three-dimensional information of the burden surface in high temperature and excessive dust industrial conditions has been previously hard to obtain. This paper presents a novel microstrip-fed dielectric-filled waveguide antenna element which is resistant to dust and high temperatures. A novel microstrip-to-dielectric-loaded waveguide transition was developed. A cylinder and cuboid composite structure was employed at the terminal of the antenna element, which improved the return loss performance and reduced the size. The proposed antenna element was easily integrated into a T-shape multiple-input multiple-output (MIMO imaging radar system and tested in both the laboratory environment and real blast furnace environment. The measurement results show that the proposed antenna element works very well in industrial 3D imaging radar.
Xu, Ding; Li, Zhiping; Chen, Xianzhong; Wang, Zhengpeng; Wu, Jianhua
2016-01-01
Three-dimensional information of the burden surface in high temperature and excessive dust industrial conditions has been previously hard to obtain. This paper presents a novel microstrip-fed dielectric-filled waveguide antenna element which is resistant to dust and high temperatures. A novel microstrip-to-dielectric-loaded waveguide transition was developed. A cylinder and cuboid composite structure was employed at the terminal of the antenna element, which improved the return loss performance and reduced the size. The proposed antenna element was easily integrated into a T-shape multiple-input multiple-output (MIMO) imaging radar system and tested in both the laboratory environment and real blast furnace environment. The measurement results show that the proposed antenna element works very well in industrial 3D imaging radar. PMID:27556469
Xu, Ding; Li, Zhiping; Chen, Xianzhong; Wang, Zhengpeng; Wu, Jianhua
2016-08-22
Three-dimensional information of the burden surface in high temperature and excessive dust industrial conditions has been previously hard to obtain. This paper presents a novel microstrip-fed dielectric-filled waveguide antenna element which is resistant to dust and high temperatures. A novel microstrip-to-dielectric-loaded waveguide transition was developed. A cylinder and cuboid composite structure was employed at the terminal of the antenna element, which improved the return loss performance and reduced the size. The proposed antenna element was easily integrated into a T-shape multiple-input multiple-output (MIMO) imaging radar system and tested in both the laboratory environment and real blast furnace environment. The measurement results show that the proposed antenna element works very well in industrial 3D imaging radar.
Tsai, C.; Szabo, B. A.
1973-01-01
An approch to the finite element method which utilizes families of conforming finite elements based on complete polynomials is presented. Finite element approximations based on this method converge with respect to progressively reduced element sizes as well as with respect to progressively increasing orders of approximation. Numerical results of static and dynamic applications of plates are presented to demonstrate the efficiency of the method. Comparisons are made with plate elements in NASTRAN and the high-precision plate element developed by Cowper and his co-workers. Some considerations are given to implementation of the constraint method into general purpose computer programs such as NASTRAN.
Simulation of Lamb wave reflections at plate edges using the semi-analytical finite element method.
Ahmad, Z A B; Gabbert, U
2012-09-01
In typical Lamb wave simulation practices, effects of plate edge reflections are often not considered in order to simplify the wave signal interpretations. Methods that are based on infinite plates such as the semi-analytical finite element method is effective in simulating Lamb waves as it excludes the effect of plate edges. However, the inclusion of plate edges in a finite plate could render this method inapplicable, especially for transient response simulations. Here, by applying the ratio of Lamb mode reflections at plate edges, and representing the reflection at plate edges using infinite plate solutions, the semi-analytical finite element method can be applied for transient response simulation, even when the plate is no longer infinite.
Finite-Element Modeling of Timber Joints with Punched Metal Plate Fasteners
DEFF Research Database (Denmark)
Ellegaard, Peter
2006-01-01
The focus of this paper is to describe the idea and the theory behind a finite-element model developed for analysis of timber trusses with punched metal plate fasteners (nail plates). The finite-element model includes the semirigid and nonlinear behavior of the joints (nonlinear nail and plate...... elements) and contact between timber beams, if any (bilinear contact elements). The timber beams have linear-elastic properties. The section forces needed for design of the joints are given directly by the finite-element model, since special elements are used to model the nail groups and the nail plate...... area over the joint lines. The finite-element model is based on the Foschi model, but with further improvements. After the theory of the model is described, results from experimental tests with two types of nail plate joints are compared with predictions given by the model. The model estimates...
Energy flow in plate assembles by hierarchical version of finite element method
DEFF Research Database (Denmark)
Wachulec, Marcin; Kirkegaard, Poul Henning
method has been proposed. In this paper a modified hierarchical version of finite element method is used for modelling of energy flow in plate assembles. The formulation includes description of in-plane forces so that planes lying in different planes can be modelled. Two examples considered are: L......-corner of two rectangular plates an a I-shaped plate girder made of five plates. Energy distribution among plates due to harmonic load is studied and the comparison of performance between the hierarchical and standard finite element formulation is presented....
Influence of alloying elements on mechanical properties of Al-Li plates
Institute of Scientific and Technical Information of China (English)
杨守杰; 戴圣龙; 苏彬; 颜鸣皋
2004-01-01
The effect of alloying elements such as Cu, Mn and Zr on the mechanical properties of the Al-Li plates was studied, and the grain structure, crystallographic texture and precipitates were also investigated. It is found that the element Zr has a two-fold effect on the anisotropy of mechanical properties; the addition of element Mn can reduce the crystalline texture and the anisotropy of Al-Li plates. However, the effect of Cu element appears less pronounced.
Analysis of thin plates by the weak form quadrature element method
Institute of Scientific and Technical Information of China (English)
ZHONG HongZhi; YUE ZhiGuang
2012-01-01
The recently proposed weak form quadrature element method (QEM) is applied to flexural and vibrational analysis of thin plates.The integrals involved in the variational description of a thin plate are evaluated by an efficient numerical scheme and the partial derivatives at the integration sampling points are then approximated using differential quadrature analogs.Neither the grid pattern nor the number of nodes is fixed,being adjustable according to convergence need.The C1 continuity conditions characterizing the thin plate theory are discussed and the robustness of the weak form quadrature element for thin plates against shape distortion is examined.Examples are presented and comparisons with analytical solutions and the results of the finite element method are made to demonstrate the convergence and computational efficiency of the weak form quadrature element method.It is shown that the present formulation is applicable to thin plates with varying thickness as well as uniform plates.
Boucher, C. R.; Li, Zehao; Ahheng, C. I.; Albrecht, J. D.; Ram-Mohan, L. R.
2016-04-01
Maxwell's vector field equations and their numerical solution represent significant challenges for physical domains with complex geometries. There are several limitations in the presently prevalent approaches to the calculation of field distributions in physical domains, in particular, with the vector finite elements. In order to quantify and resolve issues, we consider the modeling of the field equations for the prototypical examples of waveguides. We employ the finite element method with a new set of Hermite interpolation polynomials derived recently by us using group theoretic considerations. We show that (i) the approach presented here yields better accuracy by several orders of magnitude, with a smoother representation of fields than the vector finite elements for waveguide calculations. (ii) This method does not generate any spurious solutions that plague Lagrange finite elements, even though the C1 -continuous Hermite polynomials are also scalar in nature. (iii) We present solutions for propagating modes in inhomogeneous waveguides satisfying dispersion relations that can be derived directly, and investigate their behavior as the ratio of dielectric constants is varied both theoretically and numerically. Additional comparisons and advantages of the proposed method are detailed in this article. The Hermite interpolation polynomials are shown to provide a robust, accurate, and efficient means of solving Maxwell's equations in a variety of media, potentially offering a computationally inexpensive means of designing devices for optoelectronics and plasmonics of increasing complexity.
FINITE ELEMENT STRUCTURAL & THERMAL ANALYSIS OF LOCK PLATE
Mr. Ketan Patil; Mr. Roshan Marode; Prof. V. M. Chidri; Prof. A.J. Keche
2012-01-01
In Centrifugal Pipe Casting machine, hot molten metal is injected from one end and the other end remains closed by a covering plate having standard dimension. This covering plate is locked by a worker with the help of a spanner. This covering plate again needs to be opened after completion of casting process for the extraction of the pipe from the mould. This paper discuss mainly focused on the analysis of locking plate and its new design so that the humaninterference must be reduced to highe...
Nilsson, C.-M.; Jones, C. J. C.; Thompson, D. J.; Ryue, J.
2009-04-01
Engineering methods for modelling the generation of railway rolling noise are well established. However, these necessarily involve some simplifying assumptions to calculate the sound powers radiated by the wheel and the track. For the rail, this involves using an average vibration together with a radiation efficiency determined for a two-dimensional (2D) problem. In this paper, the sound radiation from a rail is calculated using a method based on a combination of waveguide finite elements and wavenumber boundary elements. This new method allows a number of the simplifying assumptions in the established methods to be avoided. It takes advantage of the 2D geometry of a rail to provide an efficient numerical approach but nevertheless takes into account the three-dimensional nature of the vibration and sound field and the infinite extent of the rail. The approach is used to study a conventional 'open' rail as well as an embedded tram rail of the type used for street running. In the former case it is shown that the conventional approach gives correct results and the complexity of the new method is mostly not necessary. However, for the embedded rail it is found that it is important to take into account the radiation from several wave types in the rail and embedding material. The damping effect of the embedding material on the rail vibration is directly taken into account and, for the example shown, causes the embedded rail to radiate less sound than the open rail above about 600 Hz. The free surface of the embedding material amplifies the sound radiation at some frequencies, while at other frequencies it moves out of phase with the rail and reduces the radiation efficiency. At low frequencies the radiation from the embedded rail resembles a line monopole source which produces greater power than the 'open' rail which forms a line dipole.
Wavelet Spectral Finite Elements for Wave Propagation in Composite Plates with Damages - Years 3-4
2014-05-23
proposed by Timoshenko (1921) and Timoshenko and Woinowski-Krieger (1989). Gavric (1994) developed a numerical approach to model the cross section...Hence, in this section, skin is modeled as spectral plate element and the stiffener is modeled as a Timoshenko beam element and they are coupled using a...plates using a new stiffened element. Tech. Mech. 28 (3-4), 227-236. Timoshenko , S., 1921. On the correction of transverse shear deformation of the
Natarajan, S; Bordas, S; Rabczuk, T; Kerfriden, P
2011-01-01
In this paper, the linear free flexural vibration of cracked functionally graded material plates is studied using the extended finite element method. A 4-noded quadrilateral plate bending element based on field and edge consistency requirement with 20 degrees of freedom per element is used for this study. The natural frequencies and mode shapes of simply supported and clamped square and rectangular plates are computed as a function of gradient index, crack length, crack orientation and crack location. The effect of thickness and influence of multiple cracks is also studied.
Three-Dimensional Effects in the Plate Element Analysis of Stitched Textile Composites
Glaessgen, E. H.; Raju, I. S.
2000-01-01
Three-dimensional effects related to the analysis of stitched textile composites are discussed. The method of calculation is based on the virtual crack closure technique (VCCT), and models that model the upper and lower surface of the delamination or debond with two-dimensional (2D) plate elements rather than three-dimensional (3D) solid elements. The major advantages of the plate element modeling technique are a smaller model size and simpler geometric modeling. Details of the modeling of the laminated plate and the stitching are discussed.
Joglekar, D. M.; Mitra, M.
2015-11-01
A breathing crack, due to its bilinear stiffness characteristics, modifies the frequency spectrum of a propagating dual-frequency elastic wave, and gives rise to sidebands around the probing frequency. This paper presents an analytical-numerical method to investigate such nonlinear frequency mixing resulting from the modulation effects induced by a breathing crack in 1D waveguides, such as axial rods and the Euler-Bernoulli beams. A transverse edge-crack is assumed to be present in both the waveguides, and the local flexibility caused by the crack is modeled using an equivalent spring approach. A simultaneous treatment of both the waveguides, in the framework of the Fourier transform based spectral finite element method, is presented for analyzing their response to a dual frequency excitation applied in the form of a tone-burst signal. The intermittent contact between the crack surfaces is accounted for by introducing bilinear contact forces acting at the nodes of the damage spectral element. Subsequently, an iterative approach is outlined for solving the resulting system of nonlinear simultaneous equations. Applicability of the proposed method is demonstrated by considering several test cases. The existence of sidebands and the higher order harmonics is confirmed in the frequency domain response of both the waveguides under investigation. A qualitative comparison with the previous experimental observations accentuates the utility of the proposed solution method. Additionally, the influence of the two constituent frequencies in the dual frequency excitation is assessed by varying the relative strengths of their amplitudes. A brief parametric study is performed for bringing out the effects of the relative crack depth and crack location on the degree of modulation, which is quantified in terms of the modulation parameter. Results of the present investigation can find their potential use in providing an analytical-numerical support to the studies geared towards the
Yarmoghaddam, Elahe; Rakheja, Shaloo
2017-08-01
We theoretically model the dispersion characteristics of surface plasmons in a graphene-based parallel-plate waveguide geometry using nonlinear Kerr-type core (inter-plate) dielectric. The optical nonlinearity of graphene in the terahertz band under high light intensity is specifically included in the analysis. By solving Maxwell's equations and applying appropriate boundary conditions, we show that the waveguide supports four guided plasmon modes, each of which can be categorized as either symmetric or anti-symmetric based on the electric field distribution in the structure. Of the four guided modes, two modes are similar in characteristics to the modes obtained in the structure with linear graphene coating, while the two new modes have distinct characteristics as a result of the nonlinearity of graphene. We note that the group velocity of one of the plasmon modes acquires a negative value under high light intensity. Additionally, the optical nonlinearity of the core dielectric leads to a significant enhancement in the localization length of various plasmon modes. The description of the intra-band optical conductivity of graphene incorporates effects of carrier scatterings due to charged impurities, resonant scatterers, and acoustic phonons at 300 K. The proposed structure offers flexibility to tune the waveguide characteristics and the mode index by changing light intensity and electrochemical potential in graphene for reconfigurable plasmonic devices.
2013-06-03
... COMMISSION Quality Verification for Plate-Type Uranium-Aluminum Fuel Elements for Use in Research and Test... Verification for Plate-Type Uranium-Aluminum Fuel Elements for Use in Research and Test Reactors.'' This guide... plate-type uranium-aluminum fuel elements used in research and test reactors (RTRs). ADDRESSES: Please...
Directory of Open Access Journals (Sweden)
Azaryan N. A.
2007-06-01
Full Text Available It is suggested a modification of tetragonal finite - element method, where the tasks of plate bending with taking into accountancy uninterrupted normal efforts or displacements are reduced to quadratic programming ones.
Effects of finite element formulation on optimal plate and shell structural topologies
CSIR Research Space (South Africa)
Long, CS
2009-09-01
Full Text Available The effects of selected membrane, plate and flat shell finite element formulations on optimal topologies are numerically investigated. Two different membrane components are considered. The first is a standard 4-node bilinear quadrilateral...
A mixed shear flexible finite element for the analysis of laminated plates
Putcha, N. S.; Reddy, J. N.
1984-01-01
A mixed shear flexible finite element based on the Hencky-Mindlin type shear deformation theory of laminated plates is presented and their behavior in bending is investigated. The element consists of three displacements, two rotations, and three moments as the generalized degrees of freedom per node. The numerical convergence and accuracy characteristics of the element are investigated by comparing the finite element solutions with the exact solutions. The present study shows that reduced-order integration of the stiffness coefficients due to shear is necessary to obtain accurate results for thin plates.
Effect of Rare Earth Elements on Depositing Rate of Nickel Alloy Brush Plating Coating
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
The effect of four kinds of rare earth elements on the depositing rate of Ni-based alloy brush plating coatings was investigated. The results indicate that all of the selected rare earth elements increase the depositing rate of Ni-based alloy coatings, and Sm increases the depositing rate most obviously. There is an optimum amount of rare earth addition in the plating solution. With the change of plating voltage to a certain extent, the results reveal no differences. The mechanism of the increase of the depositing rate was analyzed.
Energy flow in plate assembles by hierarchical version of finite element method
DEFF Research Database (Denmark)
Wachulec, Marcin; Kirkegaard, Poul Henning
method has been proposed. In this paper a modified hierarchical version of finite element method is used for modelling of energy flow in plate assembles. The formulation includes description of in-plane forces so that planes lying in different planes can be modelled. Two examples considered are: L......The dynamic analysis of structures in medium and high frequencies are usually focused on frequency and spatial averages of energy of components, and not the displacement/velocity fields. This is especially true for structure-borne noise modelling. For the analysis of complicated structures......-corner of two rectangular plates an a I-shaped plate girder made of five plates. Energy distribution among plates due to harmonic load is studied and the comparison of performance between the hierarchical and standard finite element formulation is presented....
Directory of Open Access Journals (Sweden)
Stefano Valvano
2017-04-01
Full Text Available In this paper a new plate finite element (FE for the analysis of composite and sandwich plates is proposed. By making use of the node-variable plate theory assumptions, the new finite element allows for a simultaneous analysis of different subregions of the problem domain with different kinematics and accuracy, in a global/local sense. In particular higher-order theories with an Equivalent-Single-Layer (ESL approach are simultaneously used with advanced Layer-Wise (LW models. As a consequence, the computational costs can be reduced drastically by assuming refined theories only in those zones/nodes of the structural domain where the resulting strain and stress states present a complex distribution. On the contrary, computationally cheaper, low-order kinematic assumptions can be used in the remaining parts of the plate where a localized detailed analysis is not necessary. The primary advantage of the present variable-kinematics element and related global/local approach is that no ad-hoc techniques and mathematical artifices are required to mix the fields coming from two different and kinematically incompatible adjacent elements, because the plate structural theory varies within the finite element itself. In other words, the structural theory of the plate element is a property of the FE node in this present approach, and the continuity between two adjacent elements is ensured by adopting the same kinematics at the interface nodes. According to the Unified Formulation by Carrera, the through-the-thickness unknowns are described by Taylor polynomial expansions with ESL approach and by Legendre polynomials with LW approach. Furthermore, the Mixed Interpolated Tensorial Components (MITC method is employed to contrast the shear locking phenomenon. Several numerical investigations are carried out to validate and demonstrate the accuracy and efficiency of the present plate element, including comparison with various closed-form and FE solutions from the
Finding an optimization of the plate element of Egyptian research reactor using genetic algorithm
Institute of Scientific and Technical Information of China (English)
WAHED Mohamed; IBRAHIM Wesam; EFFAT Ahmed
2008-01-01
The second Egyptian research reactor ET-RR-2 went critical on the 27th of November 1997. The National Center of Nuclear Safety and Radiation Control (NCNSRC) has the responsibility of the evaluation and assessment of the safety of this reactor. The purpose of this paper is to present an approach to optimization of the fuel element plate.For an efficient search through the solution space we use a multi objective genetic algorithm which allows us to identify a set of Pareto optimal solutions providing the decision maker with the complete spectrum of optimal solutions with respect to the various targets. The aim of this paper is to propose a new approach for optimizing the fuel element plate in the reactor. The fuel element plate is designed with a view to improve reliability and lifetime and it is one of the most important elements during the shut down. In this present paper, we present a conceptual design approach for fuel element plate, in conjunction with a genetic algorithm to obtain a fuel plate that maximizes a fitness value to optimize the safety design of the fuel plate.
Two lower order nonconforming quadrilateral elements for the Reissner-Mindlin plate
Institute of Scientific and Technical Information of China (English)
2008-01-01
This paper generalizes two nonconforming rectangular elements of the Reissner-Mindlin plate to the quadrilateral mesh. The first quadrilateral element uses the usual conforming bilinear element to approximate both components of the rotation, and the modified nonconforming rotated Q1 element enriched with the intersected term on each element to approximate the displacement, whereas the second one uses the enriched modified nonconforming rotated Q1 element to approximate both the rotation and the displacement. Both elements employ a more complicated shear force space to overcome the shear force locking, which will be described in detail in the introduction. We prove that both methods converge at optimal rates uniformly in the plate thickness t and the mesh distortion parameter in both the H1-and the L2-norms, and consequently they are locking free.
Two lower order nonconforming quadrilateral elements for the Reissner-Mindlin plate
Institute of Scientific and Technical Information of China (English)
HU Jun; SHI ZhongCi
2008-01-01
This paper generalizes two nonconforming rectangular elements of the Reissner-Mindlin plate to the quadrilateral mesh.The first quadrilateral element uses the usual conforming bilinear element to approximate both components of the rotation,and the modified nonconforming rotated Q1 element enriched with the intersected term on each element to approximate the displacement,whereas the second one uses the enriched modified nonconforming rotated Q1 element to approximate both the rotation and the displacement.Both elements employ a more complicated shear force space to overcome the shear force locking,which will be described in detail in the introduction.We prove that both methods converge at optimal rates uniformly in the plate thickness t and the mesh distortion parameter in both the H1-and the L2-norms,and consequently they are locking free.
A refined mixed shear flexible finite element for the nonlinear analysis of laminated plates
Putcha, N. S.; Reddy, J. N.
1986-01-01
The present study is concerned with the development of a mixed shear flexible finite element with relaxed continuity for the geometrically linear and nonlinear analysis of laminated anisotropic plates. The formulation of the element is based on a refined higher-order theory. This theory satisfies the zero transverse shear stress boundary conditions on the top and bottom faces of the plate. Shear correction coefficients are not needed. The developed element consists of 11 degrees-of-freedom per node, taking into account three displacements, two rotations, and six moment resultants. An evaluation of the element is conducted with respect to the accuracy obtained in the bending of laminated anistropic rectangular plates with different lamination schemes, loadings, and boundary conditions.
FINITE ELEMENT IMPLEMENTATION OF DELAMINATION IN COMPOSITE PLATES
Directory of Open Access Journals (Sweden)
Milan Žmindák
2012-12-01
Full Text Available Modelling of composite structures by finite element (FE codes to effectively model certain critical failure modes such as delamination is limited. Previous efforts to model delamination and debonding failure modes using FE codes have typically relied on ad hoc failure criteria and quasi-static fracture data. Improvements to these modelling procedures can be made by using an approach based on fracture mechanics. A study of modelling delamination using the finite element code ANSYS was conducted. This investigation demonstrates the modelling of composites through improved delamination modelling. Further developments to this approach may be improved.
Impact Of Screen Ruling on the Formation of the Printing Elements on the Flexographic Printing Plate
Directory of Open Access Journals (Sweden)
Tamara Tomašegović
2013-04-01
Full Text Available Flexography is a printing technique widely used in the packaging production. The main feature of the flexography is the usage of the printing plate which is elastically deformed during the reproduction process. The printing plate is made of elastic material, rubber or nowadays mainly of different types of photopolymer. Elasticity of the plate enables printing on a wide range of printing substrates (papers, foils, board, magazines, hygienic papers etc., which is one of its advantages compared to other printing techniques. On the other hand, deformations of the printing plate in the printing process caused by the pressure between the printing plate and substrate present major limitation of the flexography. Beside functional properties of the printing plate in the printing process, the plate making process including photopolymerization highly influences the value of the halftones on the printing plate, and consequently on the final product. The aim of this paper is to examine the influence of the screen ruling on the formation of the printing elements and the procedure of the printing plate making process adjustment in order to achieve optimal quality of the printing plate and, therefore, the final product. Results have shown that the usage of different screen ruling is of great significance in processes of printing plate curve adjustment. It was proven that the usage of different screen ruling highly influences the relief depth and a cross-section of the printing elements (3D analysis, which have a significant impact on the final product quality, but cannot be detected in 2D analysis.
Impact Of Screen Ruling on the Formation of the Printing Elements on the Flexographic Printing Plate
Directory of Open Access Journals (Sweden)
Tamara Tomašegović
2012-03-01
Full Text Available Flexography is a printing technique widely used in the packaging production. The main feature of the flexography is the usage of the printing plate which is elastically deformed during the reproduction process. The printing plate is made of elastic material, rubber or nowadays mainly of different types of photopolymer. Elasticity of the plate enables printing on a wide range of printing substrates (papers, foils, board, magazines, hygienic papers etc., which is one of its advantages compared to other printing techniques. On the other hand, deformations of the printing plate in the printing process caused by the pressure between the printing plate and substrate present major limitation of the flexography. Beside functional properties of the printing plate in the printing process, the plate making process including photopolymerization highly influences the value of the halftones on the printing plate, and consequently on the final product. The aim of this paper is to examine the influence of the screen ruling on the formation of the printing elements and the procedure of the printing plate making process adjustment in order to achieve optimal quality of the printing plate and, therefore, the final product.Results have shown that the usage of different screen ruling is of great significance in processes of printing plate curve adjustment. It was proven that the usage of different screen ruling highly influences the relief depth and a cross-section of the printing elements (3D analysis, which have a significant impact on the final product quality, but cannot be detected in 2D analysis.
Developments in variational methods for high performance plate and shell elements
Felippa, Carlos A.; Militello, Carmelo
1991-01-01
High performance elements are simple finite elements constructed to deliver engineering accuracy with coarse arbitrary grids. This is part of a series on the variational foundations of high-performance elements, with emphasis on plate and shell elements constructed with the free formulation (FF) and assumed natural strain (ANS) methods. Parameterized variational principles are studied that provide a common foundation for the FF and ANS methods, as well as for a combination of both. From this unified formulation a variant of the ANS formulation, called the assumed natural deviatoric strain (ANDES) formulation, emerges as an important special case. The first ANDES element, a high-performance 9 degrees of freedom triangular Kirchhoff plate bending element, is briefly described to illustrate the use of the new formulation.
AN EFFECTIVE BOUNDARY ELEMENT METHOD FOR ANALYSIS OF CRACK PROBLEMS IN A PLANE ELASTIC PLATE
Institute of Scientific and Technical Information of China (English)
YAN Xiang-qiao
2005-01-01
A simple and effective boundary element method for stress intensity factor calculation for crack problems in a plane elastic plate is presented. The boundary element method consists of the constant displacement discontinuity element presented by Crouch and Starfield and the crack-tip displacement discontinuity elements proposed by YAN Xiangqiao. In the boundary element implementation the left or the right crack-tip displacement discontinuity element was placed locally at the corresponding left or right each crack tip on top of the constant displacement discontinuity elements that cover the entire crack surface and the other boundaries. Test examples ( i. e. , a center crack in an infinite plate under tension, a circular hole and a crack in an infinite plate under tension) are included to illustrate that the numerical approach is very simple and accurate for stress intensity factor calculation of plane elasticity crack problems. In addition, specifically, the stress intensity factors of branching cracks emanating from a square hole in a rectangular plate under biaxial loads were analysed. These numerical results indicate the present numerical approach is very effective for calculating stress intensity factors of complex cracks in a 2-D finite body, and are used to reveal the effect of the biaxial loads and the cracked body geometry on stress intensity factors.
Dynamic Stationary Response of Reinforced Plates by the Boundary Element Method
Directory of Open Access Journals (Sweden)
Luiz Carlos Facundo Sanches
2007-01-01
Full Text Available A direct version of the boundary element method (BEM is developed to model the stationary dynamic response of reinforced plate structures, such as reinforced panels in buildings, automobiles, and airplanes. The dynamic stationary fundamental solutions of thin plates and plane stress state are used to transform the governing partial differential equations into boundary integral equations (BIEs. Two sets of uncoupled BIEs are formulated, respectively, for the in-plane state (membrane and for the out-of-plane state (bending. These uncoupled systems are joined to form a macro-element, in which membrane and bending effects are present. The association of these macro-elements is able to simulate thin-walled structures, including reinforced plate structures. In the present formulation, the BIE is discretized by continuous and/or discontinuous linear elements. Four displacement integral equations are written for every boundary node. Modal data, that is, natural frequencies and the corresponding mode shapes of reinforced plates, are obtained from information contained in the frequency response functions (FRFs. A specific example is presented to illustrate the versatility of the proposed methodology. Different configurations of the reinforcements are used to simulate simply supported and clamped boundary conditions for the plate structures. The procedure is validated by comparison with results determined by the finite element method (FEM.
Automated Finite Element Analysis of Elastically-Tailored Plates
Jegley, Dawn C. (Technical Monitor); Tatting, Brian F.; Guerdal, Zafer
2003-01-01
A procedure for analyzing and designing elastically tailored composite laminates using the STAGS finite element solver has been presented. The methodology used to produce the elastic tailoring, namely computer-controlled steering of unidirectionally reinforced composite material tows, has been reduced to a handful of design parameters along with a selection of construction methods. The generality of the tow-steered ply definition provides the user a wide variety of options for laminate design, which can be automatically incorporated with any finite element model that is composed of STAGS shell elements. Furthermore, the variable stiffness parameterization is formulated so that manufacturability can be assessed during the design process, plus new ideas using tow steering concepts can be easily integrated within the general framework of the elastic tailoring definitions. Details for the necessary implementation of the tow-steering definitions within the STAGS hierarchy is provided, and the format of the ply definitions is discussed in detail to provide easy access to the elastic tailoring choices. Integration of the automated STAGS solver with laminate design software has been demonstrated, so that the large design space generated by the tow-steering options can be traversed effectively. Several design problems are presented which confirm the usefulness of the design tool as well as further establish the potential of tow-steered plies for laminate design.
Abdul-Aziz, Ali; Baaklini, George Y.; Bhatt, Ramakrishna T.
2001-01-01
Two- and three-dimensional finite element analyses were performed on uncoated and thermal barrier coated (TBC) silicon nitride plates with and without internal cooling by air. Steady-state heat-transfer analyses were done to optimize the size and the geometry of the cooling channels to reduce thermal stresses, and to evaluate the thermal environment experienced by the plate during burner rig testing. The limited experimental data available were used to model the thermal profile exerted by the flame on the plate. Thermal stress analyses were performed to assess the stress response due to thermal loading. Contours for the temperature and the representative stresses for the plates were generated and presented for different cooling hole sizes and shapes. Analysis indicates that the TBC experienced higher stresses, and the temperature gradient was much reduced when the plate was internally cooled by air. The advantages and disadvantages of several cooling channel layouts were evaluated.
Thermal Stress Analysis of Laminated Composite Plates using Shear Flexible Element
Directory of Open Access Journals (Sweden)
M. Ganapathi
1996-01-01
Full Text Available Using degree Centigrade shear flexible QUAD-9 plate element, stresses and deflections in composite laminated plates due to thermal loads analysed. A formulation based on first order shear deformation theory has been employed for the analysis. The effects of various parameters, such as ply-angle, number of layers, thickness and aspect ratios on stresses and deflections are brought out. The present formulation is being extended for studying composite shell structures.
Indian Academy of Sciences (India)
K Mallick; K K Sharma
2001-03-01
A new space-domain operator based on the shape function concept of finite element analysis has been developed to derive the residual maps of the Gorda Plate of western United States. The technique does not require explicit assumptions on isostatic models. Besides delineating the Gorda Plate boundary, the residual maps exhibit a close match both in their anomaly patterns and magnitudes with previously computed residual maps based on the theory of isostasy.
DUAL RECIPROCITY BOUNDARY ELEMENT METHOD FOR FLEXURAL WAVES IN THIN PLATE WITH CUTOUT
Institute of Scientific and Technical Information of China (English)
GAO Suo-wen; WANG Yue-sheng; ZHANG Zi-mao; MA Xing-rui
2005-01-01
The theoretical analysis and numerical calculation of scattering of elastic waves and dynamic stress concentrations in the thin plate with the cutout was studied using dual reciprocity boundary element method (DRM). Based on the work equivalent law, the dual reciprocity boundary integral equations for flexural waves in the thin plate were established using static fundamental solution. As illustration, numerical results for the dynamic stress concentration factors in the thin plate with a circular hole are given.The results obtained demonstrate good agreement with other reported results and show high accuracy.
Directory of Open Access Journals (Sweden)
Meng Xu
2016-01-01
Full Text Available Regarding straightening unit as the research object, considered the different of roller spacing, a mathematical model of intermesh schedule suitable to the 2800 seven-roller strong heavy plate straightening machine was deduced by the geometric method. According to the mathematical model, the intermesh schedules of several specifications of plate were calculated, and the finite element model of straightening process was established in the finite element analysis software Abaqus. By analysing, it was found that those plates after straightening cannot meet the requirement of flatness, due to the existence of the work hardening. The bending deflection of the last straightening unit was modified and the new calculation formula of intermesh schedule was obtained. The values of the modified coefficients were determined by the finite element method. The intermesh schedules of other specifications of plate were calculated by the modified calculation formula and then verified it in Abaqus. The simulation results showed that those plates after straightening meet the requirement of flatness. So, the research results provide a theoretical basis for development of a new plate straightening machine and formulation of intermesh schedule.
Vibration and Buckling Analysis of Moderately Thick Plates using Natural Element Method
Directory of Open Access Journals (Sweden)
Mohammad Etemadi
2015-07-01
Full Text Available Using natural element method (NEM, the buckling and the free vibration behaviors of moderate thick plates is studied here. The basis of NEM is natural neighbors and Voronoi cells concepts. The shape functions of nodes located in the domain is equal to the proportion of common natural neighbors area divided by area that related by each Voronoi cells. First step in analyzing the moderate thick plates is identification boundaries. This is done by nodes scattering on problem domain. Mindlin/Reissner theory is used to express the equations of moderate thick plate. First and second order shape functions obtained from natural element method are used to discretize differential equations. Using numerical integration on whole discrete equations of domain, stiffness, geometry and mass matrices of plate are obtained. Buckling loads and vibration modes are expressed by substituting these matrices in plate equations of motions. Arbitrary shapes of plate are selected for solution. Comparing the results of the current approach with those obtained by other numerical analytical methods, it is shown that natural element method can solve problems with complex areas accurately.
An Expert System to Analyze Homogeneity in Fuel Element Plates for Research Reactors
Energy Technology Data Exchange (ETDEWEB)
Tolosa, S.C.; Marajofsky, A.
2004-10-06
In the manufacturing control of Fuel Element Plates for Research Reactors, one of the problems to be addressed is how to determine the U-density homogeneity in a fuel plate and how to obtain qualitative and quantitative information in order to establish acceptance or rejection criteria for such, as well as carrying out the quality follow-up. This paper is aimed at developing computing software which implements an Unsupervised Competitive Learning Neural Network for the acknowledgment of regions belonging to a digitalized gray scale image. This program is applied to x-ray images. These images are generated when the x-ray beams go through a fuel plate of approximately 60 cm x 8 cm x 0.1 cm thick. A Nuclear Fuel Element for Research Reactors usually consists of 18 to 22 of these plates, positioned in parallel, in an arrangement of 8 x 7 cm. Carrying out the inspection of the digitalized x-ray image, the neural network detects regions with different luminous densities corresponding to U-densities in the fuel plate. This is used in quality control to detect failures and verify acceptance criteria depending on the homogeneity of the plate. This modality of inspection is important as it allows the performance of non-destructive measurements and the automatic generation of the map of U-relative densities of the fuel plate.
Investigation of Shear Stud Performance in Flat Plate Using Finite Element Analysis
Directory of Open Access Journals (Sweden)
T.S. Viswanathan
2014-09-01
Full Text Available Three types of shear stud arrangement, respectively featuring an orthogonal, a radial and a critical perimeter pattern, were evaluated numerically. A numerical investigation was conducted using the finite element software ABAQUS to evaluate their ability to resist punching shear in a flat plate. The finite element analysis here is an application of the nonlinear analysis of reinforced concrete structures using three-dimensional solid finite elements. The nonlinear characteristics of concrete were achieved by employing the concrete damaged plasticity model in the finite element program. Transverse shear stress was evaluated using finite element analysis in terms of shear stress distribution for flat plate with and without shear stud reinforcement. The model predicted that shear studs placed along the critical perimeter are more effective compared to orthogonal and radial patterns.
2012-03-22
... COMMISSION Quality Verification for Plate-Type Uranium-Aluminum Fuel Elements for Use in Research and Test...-Type Uranium-Aluminum Fuel Elements for Use in Research and Test Reactors,'' is temporarily identified... verifying the quality of plate-type uranium-aluminum fuel elements used in research and test reactors (RTRs...
Narra, Nathaniel; Valášek, Jiří; Hannula, Markus; Marcián, Petr; Sándor, George K; Hyttinen, Jari; Wolff, Jan
2014-01-03
Large mandibular continuity defects pose a significant challenge in oral maxillofacial surgery. One solution to this problem is to use computer-guided surgical planning and additive manufacturing technology to produce patient-specific reconstruction plates. However, when designing customized plates, it is important to assess potential biomechanical responses that may vary substantially depending on the size and geometry of the defect. The aim of this study was to assess the design of two customized plates using finite element method (FEM). These plates were designed for the reconstruction of the lower left mandibles of two ameloblastoma cases (patient 1/plate 1 and patient 2/plate 2) with large bone resections differing in both geometry and size. Simulations revealed maximum von Mises stresses of 63 MPa and 108 MPa in plates 1 and 2, and 65 MPa and 190 MPa in the fixation screws of patients 1 and 2. The equivalent strain induced in the bone at the screw-bone interface reached maximum values of 2739 micro-strain for patient 1 and 19,575 micro-strain for patient 2. The results demonstrate the influence of design on the stresses induced in the plate and screw bodies. Of particular note, however, are the differences in the induced strains. Unphysiologically high strains in bone adjacent to screws can cause micro-damage leading to bone resorption. This can adversely affect the anchoring capabilities of the screws. Thus, while custom plates offer optimal anatomical fit, attention should be paid to the expected physiological forces on the plates and the induced stresses and strains in the plate-screw-bone assembly.
Terahertz ﬁeld enhancement to the MV/cm regime in a tapered parallel plate waveguide
DEFF Research Database (Denmark)
Iwaszczuk, Krzysztof; Andryieuski, Andrei; Lavrinenko, Andrei;
2012-01-01
measurement of the field strength at the output of the waveguide. Field enhancement factors greater than 20 are demonstrated and record-high field strengths of > 1.4 MV/cm are reached. We find an excellent agreement between the two independent methods of field measurement and a numerical 3D full...
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
Current patch test for Mindlin plate element only satisfies the zero shear deformation condition.The patch test of non-zero constant shear for Mindlin plate problem cannot be performed.For shell element, the patch test does not even exist.Based on the theory of enhanced patch test proposed by Chen W J (2006),the authors proposed the enhanced patch test function for Mindlin plate and thin cylindrical shell elements.This enhanced patch test function can be used to assess the convergence of the Mindlin plate and cylindrical thin shell elements.
Directory of Open Access Journals (Sweden)
M. Sanbi
2015-01-01
Full Text Available Theoretical and numerical results of the modeling of a smart plate are presented for optimal active vibration control. The smart plate consists of a rectangular aluminum piezocomposite plate modeled in cantilever configuration with surface bonded thermopiezoelectric patches. The patches are symmetrically bonded on top and bottom surfaces. A generic thermopiezoelastic theory for piezocomposite plate is derived, using linear thermopiezoelastic theory and Kirchhoff assumptions. Finite element equations for the thermopiezoelastic medium are obtained by using the linear constitutive equations in Hamilton’s principle together with the finite element approximations. The structure is modelled analytically and then numerically and the results of simulations are presented in order to visualize the states of their dynamics and the state of control. The optimal control LQG-Kalman filter is applied. By using this model, the study first gives the influences of the actuator/sensor pair placement and size on the response of the smart plate. Second, the effects of thermoelastic and pyroelectric couplings on the dynamics of the structure and on the control procedure are studied and discussed. It is shown that the effectiveness of the control is not affected by the applied thermal gradient and can be applied with or without this gradient at any time of plate vibrations.
Modelling Thermal Shock in Functionally Graded Plates with Finite Element Method
Directory of Open Access Journals (Sweden)
Vyacheslav N. Burlayenko
2016-01-01
Full Text Available Thermomechanical behavior and crack propagation in a functionally graded metal/ceramic plate undergoing thermal shock are analyzed by using the finite element method. A two-dimensional plane strain functionally graded finite element has been developed within the ABAQUS software environment for this purpose. An actual material gradation has been accomplished by sampling material quantities directly at the Gauss points of the element via programming appropriate user-defined subroutines. The virtual crack closure technique is used to model a crack growth under thermal loading. Contact possible between crack lips during the crack advance is taken into account in thermomechanical simulations as well. The paper shows that the presented finite element model can be applied to provide an insight into the thermomechanical respond and failure of the metal/ceramic plate.
Directory of Open Access Journals (Sweden)
Jiang-Jun Zhou
2017-01-01
Full Text Available In this study, we developed and validated a refined three-dimensional finite element model of middle femoral comminuted fracture to compare the biomechanical stability after two kinds of plate fixation: a newly designed assembly locking compression plate (NALCP and a locking compression plate (LCP. CT data of a male volunteer was converted to middle femoral comminuted fracture finite element analysis model. The fracture was fixated by NALCP and LCP. Stress distributions were observed. Under slow walking load and torsion load, the stress distribution tendency of the two plates was roughly uniform. The anterolateral femur was the tension stress area, and the bone block shifted toward the anterolateral femur. Maximum stress was found on the lateral border of the number 5 countersink of the plate. Under a slow walking load, the NALCP maximum stress was 2.160e+03 MPa and the LCP was 8.561e+02 MPa. Under torsion load, the NALCP maximum stress was 2.260e+03 MPa and the LCP was 6.813e+02 MPa. Based on those results of finite element analysis, the NALCP can provide adequate mechanical stability for comminuted fractures, which would help fixate the bone block and promote bone healing.
3D finite element simulation of explosive welding of three-layer plates
Sui, GuoFa; Li, JinShan; Sun, Feng; Ma, Bei; Li, HongWei
2011-05-01
A 3D finite element model of the explosive welding process of three-layer plates with materials of steel-copper-copper is established. Based on the presented model, the bonding mechanism is simulated and analyzed, different detonation modes are also comparatively studied to indicate the driving force spread in few microseconds. The results show that the three layer plates bond together after many times of impact between the flyers and the base driven by detonation wave, which is damping rapidly at each impact with wavelength decreasing. The pressure at the detonation point is minimal, which induces non-bonding of the plates here. Detonation wave propagates in concentric circle both under side-midpoint detonation mode and under center-point detonation mode, but the movement of the flyer is different, which makes non-bonding easily occur at the end of detonation under side-midpoint detonation and at the center of the plate under center-point detonation.
Wake interference behind two flat plates normal to the flow - A finite-element study
Behr, M.; Tezduyar, T. E.; Higuchi, H.
1991-01-01
A finite-element model of the Navier-Stokes equations is used for numerical simulation of flow past two normal flat plates arranged side by side at Reynolds number 80 and 160. The results from this simulation indicate that when the gap between the plates is twice the width of a single plate, the individual wakes of the plates behave independently, with the antiphase vortex shedding being dominant. At smaller gap sizes, the in-phase vortex shedding, with strong wake interaction, is favored. The gap flow in those cases becomes biased, with one of the wakes engulfing the other. The direction of the biased flow was found to be switching at irregular intervals, with the time histories of the indicative flow parameters and their power spectra resembling those of a chaotic system.
Uranus, H.P.; Hoekstra, H.J.W.M.; Groesen, van E.
2004-01-01
A simple high-order Galerkin finite element scheme is formulated to compute both the guided and leaky modes of anisotropic planar waveguides with a diagonal permittivity tensor. Transparent boundary conditions derived from the Sommerfield radiation conditions are used to model the fields at the comp
Li, Xiaoda; Zhang, Xiangkui; Hu, Ping; Liu, Weijie; Shen, Guozhe; Zhan, Xianghui
2015-01-01
The locking compression plate fixation treatment for the unstable sacral fractures is simple and effective, with less trauma and complications. Some locking compression plate parts have been made of high-strength Plate manufactured by hot stamping process since the demand for lightweight biomedical materials. Finite Element (FE) method of One-Step inverse forming based on deformation theory is the tool to evaluate the formability of locking compression plate panel quickly in initial design for reducing costs and development cycle of Plate. But current one-step inverse forming methods are all suitable for cold stamping, not hot-stamping. This paper proposed one-step inverse forming method and workflow for hot-stamping of locking compression Plate. And the B pillar of a sacral bone was simulated and its computing result was compared with experimental value. The result shows that the proposed method in this paper can quickly evaluate high temperature formability of high-strength Plate. And the method is proposed to be used in initial design.
C1-continuous Virtual Element Method for Poisson-Kirchhoff plate problem
Energy Technology Data Exchange (ETDEWEB)
Gyrya, Vitaliy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mourad, Hashem Mohamed [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2016-09-20
We present a family of C1-continuous high-order Virtual Element Methods for Poisson-Kirchho plate bending problem. The convergence of the methods is tested on a variety of meshes including rectangular, quadrilateral, and meshes obtained by edge removal (i.e. highly irregular meshes). The convergence rates are presented for all of these tests.
Solomon, S. C.
1980-01-01
The measurability of changes in plate driving or resistive forces associated with plate boundary earthquakes by laser rangefinding or VLBI is considered with emphasis on those aspects of plate forces that can be characterized by such measurements. Topics covered include: (1) analytic solutions for two dimensional stress diffusion in a plate following earthquake faulting on a finite fault; (2) two dimensional finite-element solutions for the global state of stress at the Earth's surface for possible plate driving forces; and (3) finite-element solutions for three dimensional stress diffusion in a viscoelastic Earth following earthquake faulting.
Directory of Open Access Journals (Sweden)
Di Wang
2015-01-01
Full Text Available The energy density governing equation to analyze the high-frequency dynamic behavior of plates in thermal environments is derived in this paper, in which the thermal effects are considered to change the membrane stress state and temperature dependent material properties of plates. Then the thermal effects on the energy reflection and transmission coefficients are dealt with hereof. Based on the above, an EFEM (energy finite element method based approximate approach for the energy analysis of coupled plates under nonuniform thermal environments is proposed. The approach could be conducted by three steps: (1 thermal analysis, (2 thermal stress analysis, and (3 forming element matrixes, joint matrixes, and the whole EFEM formulation for the energy analysis. The same mesh model is used for all the three steps. The comparison between EFEM results and classical modal superposition method results of simply supported plates in various uniform thermal environments and coupled plates in nonuniform thermal environments demonstrated that the derived energy governing equation and the proposed approach described well the smooth time- and locally space-averaged energy density. It is found that the distributions and levels of energy density are affected by thermal effects, and the variation trends are related to exciting frequency.
Local equivalent welding element to predict the welding deformations of plate-type structures
Institute of Scientific and Technical Information of China (English)
2008-01-01
Considering the Heat Affected Zone (HAZ) of welding joint, the residual strain be-haviors of material under constraint and temperature circulation, as well as the activating mechanism of welding process, this paper addresses a new type welding element for numerical simulation of welding deformation, which is called the LEWE (the local equivalent welding element). This element can describe the basic char-acteristics of welded seam: the local position points of inherent strain, the equiva-lent size, the bending radius (or bending angle) from inherent strain, etc. It could be used to predict the welding deformation of plate-type structure. The comparisons between the computed deflection of welded plate and its experiment measurement are present. The results showed that the LEWE possesses a potential to simulate the deformation of welding process high-efficiently and precisely.
Hybrid Semiloof elements for plates and shells based upon a modified Hu-Washizu principle
Pian, T. H. H.; Sumihara, K.
1984-01-01
Hybrid SemiLoof elements for plates and shells are developed based upon modified Hu-Washizu principle. In the new version of the assumed stress hybrid formulation the equilibrium equations are satisfied through the introduction of internal displacement parameters as Lagrange multipliers. The inversion of the resulting H-matrices is simplified particularly when the stresses are expressed in terms of natural coordinates. A 24-DOF triangular element and a 32-DOF quadrilateral element based on shallow shell theory are derived and evaluated.
Shear-flexible finite-element models of laminated composite plates and shells
Noor, A. K.; Mathers, M. D.
1975-01-01
Several finite-element models are applied to the linear static, stability, and vibration analysis of laminated composite plates and shells. The study is based on linear shallow-shell theory, with the effects of shear deformation, anisotropic material behavior, and bending-extensional coupling included. Both stiffness (displacement) and mixed finite-element models are considered. Discussion is focused on the effects of shear deformation and anisotropic material behavior on the accuracy and convergence of different finite-element models. Numerical studies are presented which show the effects of increasing the order of the approximating polynomials, adding internal degrees of freedom, and using derivatives of generalized displacements as nodal parameters.
Nonconforming stabilized combined finite element method for Reissner-Mindlin plate
Institute of Scientific and Technical Information of China (English)
Min-fu FENG; Yan YANG; Tian-xiao ZHOU
2009-01-01
Based on combination of two variational principles, a nonconforming sta-bilized finite element method is presented for the Reissner-Mindlin plates. The method is convergent when the finite element space is energy-compatible. Error estimates are derived. In particular, three finite element spaces are applied in the computation. Nu-merical results show that the method is insensitive to the mesh distortion and has better performence than the MITC4 and DKQ methods. With properly chosen parameters, high accuracy can be obtained at coarse meshes.
DEFF Research Database (Denmark)
2013-01-01
A waveguide resonator comprising a number of side walls defining a cavity enclosed by said sidewalls defining the cavity; and two or more conductive plates extending into the cavity, each conductive plate having a first side and a second side opposite the first side, and wherein the conductive...
Structural Stability and Dynamics of FGM Plates Using an Improved 8-ANS Finite Element
Directory of Open Access Journals (Sweden)
Weon-Tae Park
2016-01-01
Full Text Available I investigate the vibration and buckling analysis of functionally graded material (FGM structures, using a modified 8-node shell element. The properties of FGM vary continuously through the thickness direction according to the volume fraction of constituents defined by sigmoid function. The modified 8-ANS shell element has been employed to study the effect of power law index on dynamic analysis of FGM plates with various boundary conditions and buckling analysis under combined loads, and interaction curves of FGM plates are carried out. To overcome shear and membrane locking problems, the assumed natural strain method is employed. In order to validate and compare the finite element numerical solutions, the reference results of plates based on Navier’s method, the series solutions of sigmoid FGM (S-FGM plates are compared. Results of the present study show good agreement with the reference results. The solutions of vibration and buckling analysis are numerically illustrated in a number of tables and figures to show the influence of power law index, side-to-thickness ratio, aspect ratio, types of loads, and boundary conditions in FGM structures. This work is relevant to the simulation of wing surfaces, aircrafts, and box structures under various boundary conditions and loadings.
Vibration analysis of cracked plates using the extended finite element method
Energy Technology Data Exchange (ETDEWEB)
Bachene, M. [University of Medea, Department of Mechanical Engineering, Medea (Algeria); Tiberkak, R. [University of Blida, Department of Mechanical Engineering, Blida (Algeria); Rechak, S. [National Polytechnic School of Algiers, Laboratory of Mechanical Engineering and Development, Algiers (Algeria)
2009-03-15
In the present paper, the extended finite element method (X-FEM) is adopted to analyze vibrations of cracked plates. Mindlin's plate theory taking into account the effects of shear deformation and rotatory inertia is included in the development of the model. First, conventional FEM without any discontinuity is carried out, then the enrichment proposed by Moes et al. (Int J Numer Methods Eng 46, 131-150, 1999) of nodal elements containing cracks is added to the FEM formulation. Numerical implementation of enriched elements by discontinuous functions is performed, and thus dynamic equations (stiffness and mass matrices) are established. A FORTRAN computer code based on the X-FEM formulation is hence developed. Rectangular and square plates containing through-edge and central cracks with different boundary conditions are considered. The subspace iteration method is used to solve the eigenvalue problem. Natural frequencies as well as the corresponding eigenfunctions are consequently calculated as a function of the crack length. The obtained results show that the X-FEM is an efficient method in the dynamic analysis of plates containing discontinuities. (orig.)
Institute of Scientific and Technical Information of China (English)
郑长良; 李丽华; 钟万勰
2004-01-01
The linear buckling problems of plates and shells were analysed using a recently developped quadrilateral, 16-degrees of freedom flat shell element (called DKQ16). The geometrical stiffness matrix was established. Comparison of the numerical results for several typical problems shows that the DKQ16 element has a very good precision for the linear buckling problems of plates and shells.
Directory of Open Access Journals (Sweden)
Gurinder Singh Brar
2013-06-01
Full Text Available Welding is one of the most reliable and efficient permanent metal joining processes in the industry. When two plates are joined by welding, a very complex thermal cycle is applied to the weldment. Thermal energy applied results in irreversible elastic-plastic deformation and consequently gives rise to the residual stresses in and around fusion zone and heat affected zone (HAZ. It is well established fact that structural integrity of components is substantially affected by the residual stresses when subjected to thermal and structural loads. Presence of residual stresses may be beneficial or harmful for the structural components depending on the nature and magnitude of residual stresses. Using finite element based commercially available software, coupled thermal-mechanical three dimensional finite element model was developed by making an approximate geometry of the butt welded joint. Finite element analysis was performed to understand the complete nature of residual stresses in manual metal arc welded joint of AISI 304 stainless steel plate. Variation of residual stress in the plates in the heat affected zone was also being studied. The results obtained by finite element method agree well with those from X-ray diffraction method as published in literature for the prediction of residual stresses.
Yang, Gang; Hu, De'an; Long, Shuyao
2017-02-01
A reconstructed edge-based smoothed triangular element, which is incorporated with the discrete shear gap (DSG) method, is formulated based on the global coordinate for analysis of Reissner-Mindlin plates. A symbolic integration combined with the smoothing technique is implemented to calculate the smoothed finite element matrices, which is integrated along the boundaries of each smoothing cell. Numerical results show that the proposed element is free from shear locking, and its results are in good agreement with the exact solutions, even for very thin plates with extremely distorted elements. The proposed element gives more accurate results than the original DSG element without smoothing, and it can be taken as an alternative element for analysis of Reissner-Mindlin plates. The prominent feature of the present element is that the integration scheme is unified in the smoothed form for all of the finite element matrices.
Layerwise mechanics and finite element for the dynamic analysis of piezoelectric composite plates
Saravanos, Dimitris A.; Heyliger, Paul R.; Hopkins, Dale A.
1996-01-01
Laminate and structural mechanics for the analysis of laminated composite plate structures with piezoelectric actuators and sensors are presented. The theories implement layerwise representations of displacements and electric potential, and can model both the global and local electromechanical response of smart composite laminates. Finite-element formulations are developed for the quasi-static and dynamic analysis of smart composite structures containing piezoelectric layers. Comparisons with an exact solution illustrate the accuracy, robustness and capability of the developed mechanics to capture the global and local response of thin and/or thick laminated piezoelectric plates. Additional correlations and numerical applications demonstrate the unique capabilities of the mechanics in analyzing the static and free-vibration response of composite plates with distributed piezoelectric actuators and sensors.
Institute of Scientific and Technical Information of China (English)
Song Cen; Xiangrong Fu; Yuqiu Long; Hongguang Li; Zhenhan Yao
2007-01-01
Recently, some new quadrilateral finite elements were successfully developed by the Quadrilateral Area Coordinate (QAC) method. Compared with those traditional models using isoparametric coordinates, these new models are less sensitive to mesh distortion. In this paper, a new displacement-based, 4-node 20-DOF (5-DOF per node)quadrilateral bending element based on the first-order shear deformation theory for analysis of arbitrary laminated composite plates is presented. Its bending part is based on the element AC-MQ4, a recent-developed high-performance Mindlin-Reissner plate element formulated by QAC method and the generalized conforming condition method; and its in-plane displacement fields are interpolated by bilinear shape functions in isoparametric coordinates. Furthermore,the hybrid post-processing procedure, which was firstly proposed by the authors, is employed again to improve the stress solutions, especially for the transverse shear stresses. The resulting element, denoted as AC-MQ4-LC, exhibits excellent performance in all linear static and dynamic numerical examples. It demonstrates again that the QAC method, the generalized conforming condition method, and the hybrid post-processing procedure are efficient tools for developing simple, effective and reliable finite element models.
Hansbo, Peter; Larson, Mats G.
2017-06-01
We employ surface differential calculus to derive models for Kirchhoff plates including in-plane membrane deformations. We also extend our formulation to structures of plates. For solving the resulting set of partial differential equations, we employ a finite element method based on elements that are continuous for the displacements and discontinuous for the rotations, using C^0 -elements for the discretisation of the plate as well as for the membrane deformations. Key to the formulation of the method is a convenient definition of jumps and averages of forms that are d-linear in terms of the element edge normals.
Fabrication of simulated plate fuel elements: Defining role of stress relief annealing
Kohli, D.; Rakesh, R.; Sinha, V. P.; Prasad, G. J.; Samajdar, I.
2014-04-01
This study involved fabrication of simulated plate fuel elements. Uranium silicide of actual fuel elements was replaced with yttria. The fabrication stages were otherwise identical. The final cold rolled and/or straightened plates, without stress relief, showed an inverse relationship between bond strength and out of plane residual shear stress (τ13). Stress relief of τ13 was conducted over a range of temperatures/times (200-500 °C and 15-240 min) and led to corresponding improvements in bond strength. Fastest τ13 relief was obtained through 300 °C annealing. Elimination of microscopic shear bands, through recovery and partial recrystallization, was clearly the most effective mechanism of relieving τ13.
Analysis for quadrilateral MITC elements for the Reissner-Mindlin plate problem
Hu, Jun; Shi, Zhong-Ci
2009-06-01
The present paper is made up of two parts. In the first part, we study the mathematical stability and convergence of the quadrilateral MITC elements for the Reissner-Mindlin plate problem in an abstract setting. We generalize the Brezzi-Bathe-Fortin conditions to the quadrilateral MITC elements by weakening the second and fourth conditions. Under these conditions, we show the well-posedness of the discrete problem and establish an abstract error estimate in the energy norm. The conclusion of this part is sparsity in the mathematical research of the quadrilateral MITC elements in the sense that one only needs to check these five conditions. In the second part, we extend four families of rectangular MITC elements of Stenberg and Sueri to the quadrilateral meshes. We prove that these quadrilateral elements satisfy the generalized Brezzi-Bathe-Fortin conditions from the first part. We develop the h-p error estimates in both energy and L^2 norm for these quadrilateral elements. For the first three families of quadrilateral elements, the error estimates indicate that their convergent rates in both energy and L^2 norm depend on the mesh distortion parameter alpha . We can get optimal error estimates for them provided that alpha=1 . In addition, we show the optimal convergence rates in energy norm uniformly in alpha for the fourth family of quadrilateral elements. Like their rectangular counterparts, these quadrilateral elements are locking-free.
Modeling of the heat transfer performance of plate-type dispersion nuclear fuel elements
Ding, Shurong; Huo, Yongzhong; Yan, XiaoQing
2009-08-01
Considering the mutual actions between fuel particles and the metal matrix, the three-dimensional finite element models are developed to simulate the heat transfer behaviors of dispersion nuclear fuel plates. The research results indicate that the temperatures of the fuel plate might rise more distinctly with considering the particle swelling and the degraded surface heat transfer coefficients with increasing burnup; the local heating phenomenon within the particles appears when their thermal conductivities are too low. With rise of the surface heat transfer coefficients, the temperatures within the fuel plate decrease; the temperatures of the fuel plate are sensitive to the variations of the heat transfer coefficients whose values are lower, but their effects are weakened and slight when the heat transfer coefficients increase and reach a certain extent. Increasing the heat generation rate leads to elevating the internal temperatures. The temperatures and the maximum temperature differences within the plate increase along with the particle volume fractions. The surface thermal flux goes up along with particle volume fractions and heat generation rates, but the effects of surface heat transfer coefficients are not evident.
Direct tests of micro channel plates as the active element of a new shower maximum detector
Energy Technology Data Exchange (ETDEWEB)
Ronzhin, A., E-mail: ronzhin@fnal.gov [Fermilab, Batavia, IL 60510 (United States); Los, S.; Ramberg, E. [Fermilab, Batavia, IL 60510 (United States); Apresyan, A.; Xie, S.; Spiropulu, M. [California Institute of Technology, Pasadena, CA (United States); Kim, H. [University of Chicago, Chicago, IL 60637 (United States)
2015-09-21
We continue the study of micro channel plates (MCP) as the active element of a shower maximum (SM) detector. We present below test beam results obtained with MCPs detecting directly secondary particles of an electromagnetic shower. The MCP efficiency to shower particles is close to 100%. The time resolution obtained for this new type of the SM detector is at the level of 40 ps.
Olha Sarapulova; Valentyn Sherstiuk
2015-01-01
In order to produce nanophotonic elements for smart packaging, we investigated the influence of the parameters of screen and offset gravure printing plates on features of printed application of coatings with nanophotonic components and on parameters of their photoluminescence. To determine the dependence of luminescence intensity on the thickness of solid coating, we carried out the formation of nanophotonic solid surfaces by means of screen printing with different layer thickness on polyprop...
Modeling of Acoustic Emission Signal Propagation in Waveguides
Directory of Open Access Journals (Sweden)
Andreea-Manuela Zelenyak
2015-05-01
Full Text Available Acoustic emission (AE testing is a widely used nondestructive testing (NDT method to investigate material failure. When environmental conditions are harmful for the operation of the sensors, waveguides are typically mounted in between the inspected structure and the sensor. Such waveguides can be built from different materials or have different designs in accordance with the experimental needs. All these variations can cause changes in the acoustic emission signals in terms of modal conversion, additional attenuation or shift in frequency content. A finite element method (FEM was used to model acoustic emission signal propagation in an aluminum plate with an attached waveguide and was validated against experimental data. The geometry of the waveguide is systematically changed by varying the radius and height to investigate the influence on the detected signals. Different waveguide materials were implemented and change of material properties as function of temperature were taken into account. Development of the option of modeling different waveguide options replaces the time consuming and expensive trial and error alternative of experiments. Thus, the aim of this research has important implications for those who use waveguides for AE testing.
Sepahvand, K.
2017-07-01
Damping parameters of fiber-reinforced composite possess significant uncertainty due to the structural complexity of such materials. Considering the parameters as random variables, this paper uses the generalized polynomial chaos (gPC) expansion to capture the uncertainty in the damping and frequency response function of composite plate structures. A spectral stochastic finite element formulation for damped vibration analysis of laminate plates is employed. Experimental modal data for samples of plates is used to identify and realize the range and probability distributions of uncertain damping parameters. The constructed gPC expansions for the uncertain parameters are used as inputs to a deterministic finite element model to realize random frequency responses on a few numbers of collocation points generated in random space. The realizations then are employed to estimate the unknown deterministic functions of the gPC expansion approximating the responses. Employing modal superposition method to solve harmonic analysis problem yields an efficient sparse gPC expansion representing the responses. The results show while the responses are influenced by the damping uncertainties at the mid and high frequency ranges, the impact in low frequency modes can be safely ignored. Utilizing a few random collocation points, the method indicates also a very good agreement compared to the sampling-based Monte Carlo simulations with large number of realizations. As the deterministic finite element model serves as black-box solver, the procedure can be efficiently adopted to complex structural systems with uncertain parameters in terms of computational time.
Directory of Open Access Journals (Sweden)
Olha Sarapulova
2015-01-01
Full Text Available In order to produce nanophotonic elements for smart packaging, we investigated the influence of the parameters of screen and offset gravure printing plates on features of printed application of coatings with nanophotonic components and on parameters of their photoluminescence. To determine the dependence of luminescence intensity on the thickness of solid coating, we carried out the formation of nanophotonic solid surfaces by means of screen printing with different layer thickness on polypropylene film. The obtained analytical dependencies were used to confirm the explanation of the processes that occur during the fabrication of nanophotonic coverings with offset gravure printing plates. As a result of experimental studies, it was determined that the different character of the dependency of total luminescence intensity of nanophotonic elements from the percentage of a pad is explained by the use of different types of offset gravure printing plates, where the size of raster points remains constant in one case and changes in the other case, while the depth of the printing elements accordingly changes or remains constant. To obtain nanophotonic areas with predetermined photoluminescent properties, the influence of investigated factors on changes of photoluminescent properties of nanophotonic printed surfaces should be taken into consideration.
Using Plate Finite Elements for Modeling Fillets in Design, Optimization, and Dynamic Analysis
Brown, A. M.; Seugling, R. M.
2003-01-01
A methodology has been developed that allows the use of plate elements instead of numerically inefficient solid elements for modeling structures with 90 degree fillets. The technique uses plate bridges with pseudo Young's modulus (Eb) and thickness (tb) values placed between the tangent points of the fillets. These parameters are obtained by solving two nonlinear simultaneous equations in terms of the independent variables rlt and twallt. These equations are generated by equating the rotation at the tangent point of a bridge system with that of a fillet, where both rotations are derived using beam theory. Accurate surface fits of the solutions are also presented to provide the user with closed-form equations for the parameters. The methodology was verified on the subcomponent level and with a representative filleted structure, where the technique yielded a plate model exhibiting a level of accuracy better than or equal to a high-fidelity solid model and with a 90-percent reduction in the number of DOFs. The application of this method for parametric design studies, optimization, and dynamic analysis should prove extremely beneficial for the finite element practitioner. Although the method does not attempt to produce accurate stresses in the filleted region, it can also be used to obtain stresses elsewhere in the structure for preliminary analysis. A future avenue of study is to extend the theory developed here to other fillet geometries, including fillet angles other than 90 and multifaceted intersections.
Oki, Sae; Suzuki, Ryosuke O.
2016-09-01
The performance of a flat-plate thermoelectric (TE) module consisting of square truncated pyramid elements is simulated using commercial software and original TE programs. Assuming that the temperatures of both the hot and cold surfaces are constant, the performance can be varied by changing the element shape and element alignment pattern. When the angle between the edge and the base is 85° and the small square surfaces of all n-type element faces are connected to the low-temperature surface, the efficiency becomes the largest among all the 17 examined shapes and patterns. By changing the shape to match the temperature distribution, the performance of the TE module is maximized.
Duan, M.
2004-12-01
In this paper, a geometrically nonlinear hybrid/mixed curved quadrilateral shell element (HMSHEL4N) with four nodes is developed based on the modified Hellinger/Reissner variational principles. The performance of element is investigated and tested using some benchmark problems. A number of numerical examples of plate and shell nonlinear deflection problems are included. The results are compared with theoretical solutions and other numerical results. It is shown that HMSHEL4N does not possess spurious zero energy modes and any locking phenomenon, and is convergent and insensitive to the distorted mesh. A good agreement of the results with theoretical solutions, and better performance compared with displacement finite element method, are observed. It is seen that an efficient shell element based on stress and displacement field assumptions in solution and time is obtained.
Finite Element - Artificial Transmitting Boundary Method for Acoustical Field on Tapered Waveguide
Institute of Scientific and Technical Information of China (English)
J.; S.; Yang; G; F.; Fan; J.; P.; Zhu; C.K.; Sun; Y.; H.; Zhu
2003-01-01
In earlier approach, the 2-D acoustical field profiles on the substrate region are often calculated with BPM. In this paper, we present a new approach based on the finite element -artificial transmitting boundary method and calculate acoustical field on the substrate region.
Kapania, R. K.; Mohan, P.
1996-09-01
Finite element static, free vibration and thermal analysis of thin laminated plates and shells using a three noded triangular flat shell element is presented. The flat shell element is a combination of the Discrete Kirchhoff Theory (DKT) plate bending element and a membrane element derived from the Linear Strain Triangular (LST) element with a total of 18 degrees of freedom (3 translations and 3 rotations per node). Explicit formulations are used for the membrane, bending and membrane-bending coupling stiffness matrices and the thermal load vector. Due to a strong analogy between the induced strain caused by the thermal field and the strain induced in a structure due to an electric field the present formulation is readily applicable for the analysis of structures excited by surface bonded or embedded piezoelectric actuators. The results are presented for (i) static analysis of (a) simply supported square plates under doubly sinusoidal load and uniformly distributed load (b) simply supported spherical shells under a uniformly distributed load, (ii) free vibration analysis of (a) square cantilever plates, (b) skew cantilever plates and (c) simply supported spherical shells; (iii) Thermal deformation analysis of (a) simply supported square plates, (b) simply supported-clamped square plate and (c) simply supported spherical shells. A numerical example is also presented demonstrating the application of the present formulation to analyse a symmetrically laminated graphite/epoxy laminate excited by a layer of piezoelectric polyvinylidene flouride (PVDF). The results presented are in good agreement with those available in the literature.
Liu, Xi-Ming; Pan, Chang-Wu; Wang, Guo-Dong; Cai, Xian-Hua; Chen, Lei; Meng, Cheng-Fei; Huang, Jin-Cheng
2015-01-01
This study aims to explore the mechanical stability of combined plate internal fixation in posterior wall fractures of the acetabulum. The fracture and internal fixation models were established in this study and they were divided into four kinds of internal fixation models, finite element analysis was performed. The four groups were 2 mini-plates and 1 reconstruction plate fixation (A), Reconstruction plate internal fixation group (B), 2 screws internal fixation group (C) and mini-plates internal fixation group (D). The displacement of each node was measured and evaluated. There was no distortion in the geometric shape of the finite element model. The results of stress showed that it was less in the anterior pelvic ring and distributed uniform in labrum acetabulare; the stress was bigger in the upper and middle of sacroiliac joint and sciatic notch in sitting position. Combined plate internal fixation for posterior wall fractures of acetabular were stable and reliable, it is better than the other three methods.
Novel thin plate element theory based on a continuity re-relaxed technique
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
Thin plate problem has been receiving much interest due to its wide application in engineering.In this paper,a novel thin plate element theory is proposed based on a continuity re-relaxed technique to avoid the high continuity requirement for thin plate formulation which needs the high computation cost.The problem is first discretized into a set of background cells with field nodes,and only deflection field is treated as the field variable.On top of the background cells,the integration domains are further formed.The curvatures over integration domains are restructured through the divergence theorem,and the continuity requirement of the trial deflection function for thin plate problems can be re-relaxed.The Galerkin weak form is then used to create the discretized system equations.The curvatures in the integration domains are constant,and the stiffness matrix of the system can be computed directly without numerical integration.The rotational essential boundary conditions are imposed in the process of curvature field construction.Some numerical examples are computed using the RPIM approximation function.The excellent results demonstrate the efficiency of the proposed method.
Directory of Open Access Journals (Sweden)
S. N. S. Jamaludin
2014-01-01
Full Text Available The composition of hydroxyapatite (HA as the ceramic phase and titanium (Ti as the metallic phase in HA/Ti functionally graded materials (FGMs shows an excellent combination of high biocompatibility and high mechanical properties in a structure. Because the gradation of these properties is one of the factors that affects the response of the functionally graded (FG plates, this paper is presented to show the domination of the grading parameter on the displacement and stress distribution of the plates. A three-dimensional (3D thermomechanical model of a 20-node brick quadratic element is used in the simulation of the thermoelastic behaviors of HA/Ti FG plates subjected to constant and functional thermal, mechanical, and thermomechanical loadings. The convergence properties of the present results are examined thoroughly in order to assess the accuracy of the theory applied and to compare them with the established research results. Instead of the grading parameter, this study reveals that the loading field distribution can be another factor that reflects the thermoelastic properties of the HA/Ti FG plates. The FG structure is found to be able to withstand the thermal stresses while preserving the high toughness properties and thus shows its ability to operate at high temperature.
Analysis of Nonlinear Vibration of Hard Coating Thin Plate by Finite Element Iteration Method
Directory of Open Access Journals (Sweden)
Hui Li
2014-01-01
Full Text Available This paper studies nonlinear vibration mechanism of hard coating thin plate based on macroscopic vibration theory and proposes finite element iteration method (FEIM to theoretically calculate its nature frequency and vibration response. First of all, strain dependent mechanical property of hard coating is briefly introduced and polynomial method is adopted to characterize the storage and loss modulus of coating material. Then, the principle formulas of inherent and dynamic response characteristics of the hard coating composite plate are derived. And consequently specific analysis procedure is proposed by combining ANSYS APDL and self-designed MATLAB program. Finally, a composite plate coated with MgO + Al2O3 is taken as a study object and both nonlinear vibration test and analysis are conducted on the plate specimen with considering strain dependent mechanical parameters of hard coating. Through comparing the resulting frequency and response results, the practicability and reliability of FEIM have been verified and the corresponding analysis results can provide an important reference for further study on nonlinear vibration mechanism of hard coating composite structure.
Shape optimization of plate with static and dynamic constraints via virtual laminated element
Institute of Scientific and Technical Information of China (English)
李芳; 徐兴; 凌道盛
2003-01-01
The virtual laminated element method (VLEM) can resolve structural shape optimization problems with a new method. According to the characteristics of VLEM , only some characterized layer thickness values need be defined as design variables instead of boundary node coordinates or some other parameters determining the system boundary. One of the important features of this method is that it is not necessary to regenerate the FE(finite element) grid during the optimization process so as to avoid optimization failures resulting from some distortion grid elements. The thickness distribution in thin plate optimization problems in other studies before is of stepped shape. However, in this paper, a continuous thickness distribution can be obtained after optimization using VLEM, and is more reasonable. Furthermore, an approximate reanalysis method named ″behavior model technique″ can be used to reduce the amount of structural reanalysis. Some typical examples are offered to prove the effectiveness and practicality of the proposed method.
Local Projection-Based Stabilized Mixed Finite Element Methods for Kirchhoff Plate Bending Problems
Directory of Open Access Journals (Sweden)
Xuehai Huang
2013-01-01
Full Text Available Based on stress-deflection variational formulation, we propose a family of local projection-based stabilized mixed finite element methods for Kirchhoff plate bending problems. According to the error equations, we obtain the error estimates of the approximation to stress tensor in energy norm. And by duality argument, error estimates of the approximation to deflection in H1-norm are achieved. Then we design an a posteriori error estimator which is closely related to the equilibrium equation, constitutive equation, and nonconformity of the finite element spaces. With the help of Zienkiewicz-Guzmán-Neilan element spaces, we prove the reliability of the a posteriori error estimator. And the efficiency of the a posteriori error estimator is proved by standard bubble function argument.
Shape optimization of plate with static and dynamic constraints via virtual laminated element.
Li, Fang; Xu, Xing; Ling, Dao-Sheng
2003-01-01
The virtual laminated element method (VLEM) can resolve structural shape optimization problems with a new method. According to the characteristics of VLEM, only some characterised layer thickness values need be defined as design variables instead of boundary node coordinates or some other parameters determining the system boundary. One of the important features of this method is that it is not necessary to regenerate the FE(finite element) grid during the optimization process so as to avoid optimization failures resulting from some distortion grid elements. The thickness distribution in thin plate optimization problems in other studies before is of stepped shape. However, in this paper, a continuous thickness distribution can be obtained after optimization using VLEM, and is more reasonable. Furthermore, an approximate reanalysis method named "behavior model technique" can be used to reduce the amount of structural reanalysis. Some typical examples are offered to prove the effectiveness and practicality of the proposed method.
Fabrication of simulated plate fuel elements: Defining role of out-of-plane residual shear stress
Rakesh, R.; Kohli, D.; Sinha, V. P.; Prasad, G. J.; Samajdar, I.
2014-02-01
Bond strength and microstructural developments were investigated during fabrication of simulated plate fuel elements. The study involved roll bonding of aluminum-aluminum (case A) and aluminum-aluminum + yttria (Y2O3) dispersion (case B). Case B approximated aluminum-uranium silicide (U3Si2) 'fuel-meat' in an actual plate fuel. Samples after different stages of fabrication, hot and cold rolling, were investigated through peel and pull tests, micro-hardness, residual stresses, electron and micro-focus X-ray diffraction. Measurements revealed a clear drop in bond strength during cold rolling: an observation unique to case B. This was related to significant increase in 'out-of-plane' residual shear stresses near the clad/dispersion interface, and not from visible signatures of microstructural heterogeneities.
Metamaterial Loadings for Waveguide Miniaturization
Odabasi, H
2013-01-01
We show that a rectangular metallic waveguide loaded with metamaterial elements consisting of electric-field coupled (ELC) resonators placed at the side walls can operate well below the cutoff frequency of the respective unloaded waveguide. The dispersion diagrams indicate that propagating modes in ELC-loaded waveguides are of forward-type for both TE and TM modes. We also study the dispersion diagram and transmission characteristics of rectangular metallic waveguides simultaneously loaded with ELCs and split ring resonators (SRRs). Such doubly-loaded waveguides can support both forward wave and backward waves, and provide independent control of the propagation characteristics for the respective modes.
ON MORTAR-TYPE TRUNC ELEMENT METHOD FOR PLATE BENDING PROBOEM
Institute of Scientific and Technical Information of China (English)
刘庆; 李立康
2002-01-01
Wepresnet a brief introduction of applying the idea of mortar method to locally non-conforming TRUNC element for solving plate bending problem. At the interfaces, three mortarconditions, one for the value of solution in pointwise way, the other two for the normal and tan-gential derivatives of the solution in projection way, are provided to secure the global conver-gence. A fte some detailed analysis, we obtain that its error estimates in both energy norm and dis-crete H1 norm are optimal for u* ∈ H3 (Ω)∩ H20(Ω).
Finite element formulation of active constraining layer damping plate using laminate theory
Institute of Scientific and Technical Information of China (English)
邓年春; 邹振祝; 黄文虎
2004-01-01
A new finite element modeling method has been developed using laminate theory in a virlual work principle for active constraining layer damping plate. The frequency dependent modulus of viscoelastic material is described by introducing a few dissipation coordinates, known as GHM (Golla-Hughes-McTavish) method, a standard linear system with constant coefficient. The effectiveness of this method is validated by experimental model. Compared with conventional methods, this method can reduce a number of degrees of freedom and improve accuracy, provides a good model for analogous configurations.
Energy Technology Data Exchange (ETDEWEB)
Ghomshei, Mansour Mohieddin; Abbasi, Vahid [Islamic Azad University, Alborz (Iran, Islamic Republic of)
2013-04-15
In this paper, a finite element formulation is developed for analyzing the axisymmetric thermal buckling of FGM annular plates of variable thickness subjected to thermal loads generally distributed nonuniformly along the plate radial coordinate. The FGM assumed to be isotropic with material properties graded in the thickness direction according to a simple power-law in terms of the plate thickness coordinate, and has symmetry with respect to the plate midplane. At first, the pre-buckling plane elasticity problem is developed and solved using the finite element method, to determine the distribution of the pre-buckling in-plane forces in terms of the temperature rise distribution. Subsequently, based on Kierchhoff plate theory and using the principle of minimum total potential energy, the weak form of the differential equation governing the plate thermal stability is derived, then by employing the finite element method, the stability equations are solved numerically to evaluate the thermal buckling load factor. Convergence and validation of the presented finite element model are investigated by comparing the numerical results with those available in the literature. Parametric studies are carried out to cover the effects of parameters including thickness-to-radius ratio, taper parameter and boundary conditions on the thermal buckling load factor of the plates.
Finite Element-Derived Surrogate Models of Locked Plate Fracture Fixation Biomechanics.
Wee, Hwabok; Reid, J Spence; Chinchilli, Vernon M; Lewis, Gregory S
2017-03-01
Internal fixation of bone fractures using plates and screws involves many choices-implant type, material, sizes, and geometric configuration-made by the surgeon. These decisions can be important for providing adequate stability to promote healing and prevent implant mechanical failure. The purpose of this study was to develop mathematical models of the relationships between fracture fixation construct parameters and resulting 3D biomechanics, based on parametric computer simulations. Finite element models of hundreds of different locked plate fixation constructs for midshaft diaphyseal fractures were systematically assembled using custom algorithms, and axial, torsional, and bending loadings were simulated. Multivariate regression was used to fit response surface polynomial equations relating fixation design parameters to outputs including maximum implant stresses, axial and shear strain at the fracture site, and construct stiffness. Surrogate models with as little as three regressors showed good fitting (R (2) = 0.62-0.97). Inner working length was the strongest predictor of maximum plate and screw stresses, and a variety of quadratic and interaction terms influenced resulting biomechanics. The framework presented in this study can be applied to additional types of bone fractures to provide clinicians and implant designers with clinical insight, surgical optimization, and a comprehensive mathematical description of biomechanics.
3D Finite Element Numerical Simulation of Residual Stresses on Electron Beam Welded BT20 Plates
Institute of Scientific and Technical Information of China (English)
Lixing HUO; Furong CHEN; Yufeng ZHANG; Li ZHANG; Fangjun LIU; Gang CHEN
2004-01-01
A three-dimensional finite-element model (FEM) used for calculating electron beam (EB) welding temperature and stresses fields of thin plates of BT20 titanium has been developed in which the nonlinear thermophysical and thermo-mechanical properties of the material has been considered. The welding temperature field, the distributions of residual stresses in aswelded (AW) and electron beam local post-weld heat treatment (EBLPWHT) conditions have been successfully simulated.The results show that: (1) In the weld center, the maximum magnitude of residual tensile stresses of BT20 thin plates of Ti alloy is equal to 60%～ 70% of its yield strength σs. (2) The residual tensile stresses in weld center can be even decreased after EBLPWHT and the longitudinal tensile stresses are decreased about 50% compared to joints in AW conditions. (3)The numerical calculating results of residual stresses by using FEM are basically in agreement with the experimental results.Combined with numerical calculating results, the effects of electron beam welding and EBLPWHT on the distribution of welding residual stresses in thin plates of BT20 have been analyzed in detail.
Direct tests of a pixelated microchannel plate as the active element of a shower maximum detector
Apresyan, A.; Los, S.; Pena, C.; Presutti, F.; Ronzhin, A.; Spiropulu, M.; Xie, S.
2016-08-01
One possibility to make a fast and radiation resistant shower maximum detector is to use a secondary emitter as an active element. We report our studies of microchannel plate photomultipliers (MCPs) as the active element of a shower-maximum detector. We present test beam results obtained using Photonis XP85011 to detect secondary particles of an electromagnetic shower. We focus on the use of the multiple pixels on the Photonis MCP in order to find a transverse two-dimensional shower distribution. A spatial resolution of 0.8 mm was obtained with an 8 GeV electron beam. A method for measuring the arrival time resolution for electromagnetic showers is presented, and we show that time resolution better than 40 ps can be achieved.
Finite-Element Analysis of Jute- and Coir-Fiber-Reinforced Hybrid Composite Multipanel Plates
Nirbhay, M.; Misra, R. K.; Dixit, A.
2015-09-01
Natural-fiber-reinforced polymer composite materials are rapidly gaining interest worldwide both in terms of research and industrial applications. The present work includes the characterization and modeling of jute- and coir-fiber-reinforced hybrid composite materials. The mechanical behavior of a two-panel plate and a sixpanel box structure is analyzed under various loading regimes by using the finite-element software ABAQUS®. Exhaustive parametric studies are also performed to obtain a clear insight into the relationships between various parameters and deflections of the panels and stress distributions in them. Deflections of both the structures are compared and found to be in good agreement with published results. To determine the mechanical behavior of natural-fiber-reinforced composite panels, a finite-element analysis is performed.
Direct tests of a pixelated microchannel plate as the active element of a shower maximum detector
Energy Technology Data Exchange (ETDEWEB)
Apresyan, A. [California Institute of Technology, Pasadena, CA (United States); Los, S. [Fermi National Accelerator Laboratory, Batavia, IL (United States); Pena, C.; Presutti, F. [California Institute of Technology, Pasadena, CA (United States); Ronzhin, A. [Fermi National Accelerator Laboratory, Batavia, IL (United States); Spiropulu, M.; Xie, S. [California Institute of Technology, Pasadena, CA (United States)
2016-08-21
One possibility to make a fast and radiation resistant shower maximum detector is to use a secondary emitter as an active element. We report our studies of microchannel plate photomultipliers (MCPs) as the active element of a shower-maximum detector. We present test beam results obtained using Photonis XP85011 to detect secondary particles of an electromagnetic shower. We focus on the use of the multiple pixels on the Photonis MCP in order to find a transverse two-dimensional shower distribution. A spatial resolution of 0.8 mm was obtained with an 8 GeV electron beam. A method for measuring the arrival time resolution for electromagnetic showers is presented, and we show that time resolution better than 40 ps can be achieved.
A SIMPLE FINITE ELEMENT FOR NON-LINEAR ANALYSIS OF COMPOSITE PLATES
Directory of Open Access Journals (Sweden)
V.B. Tungikar
2011-06-01
Full Text Available Finite Element Analysis for geometrically nonlinear behaviour of laminated composite plates is presented andcompared with the reported investigations. However structural non-linearity is encountered in certain cases andneeds attention. A higher order displacement field that accounts for transverse shear effects under geometricnonlinear condition is employed in the formulation of a four node, rectangular, element with thirteen degrees offreedom per node. First order Zigzag terms have been included in displacement field for improvement in theresponse. Von Karman strain approach is considered in the present analysis. Incremental Pica iterative scheme isused to solve resulting nonlinear equilibrium equations. The formulation demonstrates its excellence in theperformance for predicting response at various lay ups and plies conditions.
Effect of crack on the impact response of plates by the extended finite element method (X-FEM)
Energy Technology Data Exchange (ETDEWEB)
Tiberkak, Rachid [University of Blida, Soumaa (Algeria); Bachene, Mourad [University of Medea, Medea (Algeria); Rechak, Said [Ecole Nationale Polytechnique, Algiers (Algeria)
2014-06-15
The dynamic response of cracked isotropic plates subjected to impact loading is studied in this paper. The impact properties of cracked plate are compared with the virgin ones to predict the eventual presence of discontinuities in plates. The extended finite element method (X-FEM) is employed in the mathematical modeling of the impact problem, wherein the effects of shear deformation is considered. Conventional finite element without any discontinuity is initially conducted in the numerical implementation. Enriched functions are then added to the nodal displacement field for element nodes that contain cracks. The effects of crack length and crack position on contact force and on plate deflection are analyzed. Results show that the maximal contact force decreases as the deflection increases with increasing crack length a . The effect of crack position on the dynamic response is less pronounced when the crack is near the fixed end.
FEM Simulations of Leaky Lamb Wave in Ultrasonic Waveguide Sensor
Energy Technology Data Exchange (ETDEWEB)
Bae, Jin Ho; Joo, Young Sang; Kim, Jong Bum [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2011-05-15
As the sodium coolant of a sodium-cooled fast reactor (SFR) is opaque to light, a conventional visual inspection cannot be used for carrying out an in-service inspection of the internal structures under a sodium level. An ultrasonic wave should be applied for an under-sodium viewing of the internal structures in a reactor vessel. Recently, a noble plate-type ultrasonic waveguide sensor has been developed for versatile applications in an under-sodium viewing application. The beam profile of a A{sub 0}-mode leaky Lamb wave of the waveguide sensor affects the resolution of visualization image in under-sodium viewing. In the design and manufacture of the waveguide sensor, the finite element method (FEM) modeling and simulation of the propagation of a leaky Lamb wave is required for the estimation and optimization of the waveguide sensor design parameters. In the previous research, the simple 2D modeling and simulation of the waveguide sensor had been carried out. In this work, FEM simulation of the propagation and radiation of the leaky Lamb wave in the waveguide sensor is performed for the vertical and lateral beam profile analysis using the pseudo 3D modeling including the wedge
Two-Dimensional Large Deformation Finite Element Analysis for the Pulling-up of Plate Anchor
Institute of Scientific and Technical Information of China (English)
WANG Dong; HU Yu-xia; JIN Xia
2006-01-01
Based on mesh regeneration and stress interpolation from an old mesh to a new one, a large deformation finite element model is developed for the study of the behaviour of circular plate anchors subjected to uplift loading. For the determination of the distributions of stress components across a clay foundation, the Recovery by Equilibrium in Patches is extended to plastic analyses. ABAQUS, a commercial finite element package, is customized and linked into our program so as to keep automatic and efficient running of large deformation calculation. The quality of stress interpolation is testified by evaluations of Tresca stress and nodal reaction forces. The complete pulling-up processes of plate anchors buried in homogeneous clay are simulated, and typical pulling force-displacement responses of a deep anchor and a shallow anchor are compared. Different from the results of previous studies, large deformation analysis is of the capability of estimating the breakaway between the anchor bottom and soils. For deep anchors, the variation of mobilized uplift resistance with anchor settlement is composed of three stages, and the initial buried depths of anchors affect the separation embedment slightly. The uplift bearing capacity of deep anchors is usually higher than that of shallow anchors.
Directory of Open Access Journals (Sweden)
James O’Daniel
2011-01-01
Full Text Available Simulating fragment penetration into steel involves complicated modeling of severe behavior of the materials through multiple phases of response. Penetration of a fragment-like projectile was simulated using finite element (FE and meshfree particle formulations. Extreme deformation and failure of the material during the penetration event were modeled with several approaches to evaluate each as to how well it represents the actual physics of the material and structural response. A steel Fragment Simulating Projectile (FSP – designed to simulate a fragment of metal from a weapon casing – was simulated for normal impact into a flat square plate. A range of impact velocities was used to examine levels of exit velocity ranging from relatively small to one on the same level as the impact velocity. The numerical code EPIC, used for all the simulations presented herein, contains the element and particle formulations, as well as the explicit methodology and constitutive models needed to perform these simulations. These simulations were compared against experimental data, evaluating the damage caused to the projectile and the target plates, as well as comparing the residual velocity when the projectile perforated the target.
DEFF Research Database (Denmark)
Kling, Joyce; Hjulmand, Lise-Lotte
2008-01-01
’s level of English is sufficient for the increasing number of courses offered in English each semester. This paper addresses these concerns and describes a pilot project initiated in 2003 at CBS to gauge the overall English language proficiency of those teaching content courses in English. Through......Copenhagen Business School (CBS) finds itself needing to address the issue of English-medium instruction for its increasing number of foreign exchange and full degree students. With internationalisation as a main pillar of the institution’s agenda, there are concerns whether the teaching faculty...... the Project in Language Assessment for Teaching in English (PLATE) language professionals from CBS’s Language Center observe teachers and provide feedback using evaluation criteria from the Common European Framework for Reference (CEFR) supplemented by some additional criteria which take the LSP nature...
DEFF Research Database (Denmark)
Kling, Joyce; Hjulmand, Lise-Lotte
2008-01-01
Copenhagen Business School (CBS) finds itself needing to address the issue of English-medium instruction for its increasing number of foreign exchange and full degree students. With internationalisation as a main pillar of the institution’s agenda, there are concerns whether the teaching faculty......’s level of English is sufficient for the increasing number of courses offered in English each semester. This paper addresses these concerns and describes a pilot project initiated in 2003 at CBS to gauge the overall English language proficiency of those teaching content courses in English. Through...... the Project in Language Assessment for Teaching in English (PLATE) language professionals from CBS’s Language Center observe teachers and provide feedback using evaluation criteria from the Common European Framework for Reference (CEFR) supplemented by some additional criteria which take the LSP nature...
Energy Technology Data Exchange (ETDEWEB)
Neki, I.; Tada, T. [Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan)
1996-12-31
This paper reports a method to develop a new finite element by source (FES) for a two-dimensional plane problem and a three-dimensional solid problem as a method to analyze ship body structures. The paper describes development of a plate bending element by using a similar method, and the fundamental principle thereof. The present method can prepare a finite element of an arbitrary shape by simply providing a contact point only on a boundary. It can also derive good calculation accuracy with less number of contact points and elements. These facts are shown by examples of analyses on a square plate, a triangle plate and a semi-circular plate. Particularly, since a plate bending problem has a large order of differential calculus in a governing equation, this method being a semi-analytical method derives a result with very good accuracy even with less number of contact points. A hypothetical boundary method or a hypothetical electric charge method presents not a very high accuracy even if a large number of contact points are provided. This is because the method hypothesizes only a bending moment vertical to the boundary, but does not consider a source of the moment relative to the boundary. In contrast, the present method hypothesizes both of bending and twisting as the sources, hence its accuracy is better than with the above two methods. 5 refs., 11 figs., 7 tabs.
Shape optimization of plate with static and dynamic constralnts via virtual laminated element
Institute of Scientific and Technical Information of China (English)
李芳; 徐兴; 凌道盛
2003-01-01
The virtual laminated element method(VLEM) can resolve structural shape optimization problems with a new method.According to the characteristics of VLEM,only some characterized layer thickness values need be defined as design variables instead of boundary node coordinates or some other parameters determining the system boundary.One of the important features of this method is that it is not necessary to regenerate the FE(finite element)grid during the optimization process so as to avoid optimization failures resulting from some distortion grid elements.The thickness distribution in thin plate optimization problems in other studies before is of stepped shape.However,in this paper,a continuous thickness distribution can be obtained after optimi-zation using VLEM,and is more reasonable.Furthermore,an approximate reanalysis method named "behavior model technique" can be used to reduce the amount of structural reanalysis.Sone typical examples are offered to prove the effectiveness and practicality of the proposed method.
The hp-MITC finite element method for the Reissner-Mindlin plate problem
Ainsworth, Mark; Pinchedez, Katia
2002-11-01
The popular MITC finite elements used for the approximation of the Reissner-Mindlin plate are extended to the case where elements of non-uniform degree p distribution are used on locally refined meshes. Such an extension is of particular interest to the hp-version and hp-adaptive finite element methods. A priori error bounds are provided showing that the method is locking-free. The analysis is based on new approximation theoretic results for non-uniform Brezzi-Douglas-Fortin-Marini spaces, and extends the results obtained in the case of uniform order approximation on globally quasi-uniform meshes presented by Stenberg and Suri (SIAM J. Numer. Anal. 34 (1997) 544). Numerical examples illustrating the theoretical results and comparing the performance with alternative standard Galerkin approaches are presented for two new benchmark problems with known analytic solution, including the case where the shear stress exhibits a boundary layer. The new method is observed to be locking-free and able to provide exponential rates of convergence even in the presence of boundary layers.
Lamb wave scattering by a surface-breaking crack in a plate
Datta, S. K.; Al-Nassar, Y.; Shah, A. H.
1991-01-01
An NDE method based on finite-element representation and modal expansion has been developed for solving the scattering of Lamb waves in an elastic plate waveguide. This method is very powerful for handling discontinuities of arbitrary shape, weldments of different orientations, canted cracks, etc. The advantage of the method is that it can be used to study the scattering of Lamb waves in anisotropic elastic plates and in multilayered plates as well.
DEFF Research Database (Denmark)
Cronskar, Marie; Rasmussen, John; Tinnsten, Mats
2015-01-01
This paper addresses the various treatment options for clavicle fractures by means of computational models, more precisely cases with a need for internal fixation: non-unions and certain complex fractures. The motivation for the work is that treatment can be enhanced by a better understanding...... of the loading of the clavicle and fixation device. This study aimed to develop a method for realistic simulation of stresses in the bone and fixation device in the case of a fractured clavicle. A finite element (FE) mesh of the clavicle geometry was created from computer tomography (CT) data and imported...... into the FE solver where the model was subjected to muscle forces and other boundary conditions from a multibody musculoskeletal model performing a typical activity of daily life. A reconstruction plate and screws were also imported into the model. The combination models returned stresses and displacements...
Fatigue in Welded High-Strength Steel Plate Elements under Stochastic Loading
DEFF Research Database (Denmark)
Agerskov, Henning; Petersen, R.I.; Martinez, L. Lopez
1999-01-01
The present project is a part of an investigation on fatigue in offshore structures in high-strength steel. The fatigue life of plate elements with welded attachments is studied. The material used has a yield stress of ~ 810-840 MPa, and high weldability and toughness properties. Fatigue test...... series with constant amplitude loading and with various types of stochastic loading have been carried through on test specimens in high-strength steel, and - for a comparison - on test specimens in conventional offshore structural steel with a yield stress of ~ 400-410 MPa.A comparison between constant...... amplitude and variable amplitude fatigue test results shows shorter fatigue lives in variable amplitude loading than should be expected from the linear fatigue damage accumulation formula. Furthermore, in general longer fatigue lives were obtained for the test specimens in high-strength steel than those...
Finite Element Simulation of GFRP Reinforced Concrete Beam Externally Strengthened With CFRP Plates
Directory of Open Access Journals (Sweden)
Salleh Norhafizah
2017-01-01
Full Text Available The construction technology now has become more and more advanced allowing the development of new technologies or material to replace the previous one and also solved some of the troubles confronted by construction experts. The Glass Fibre Reinforced Polymer (GFRP composite is an alternative to replace the current usage of steel as it is rust proof and stronger in terms of stiffness compared to steel. Furthermore, GFRP bars have a high strength-to-weight ratio, making them attractive as reinforcement for concrete structures. However, the tensile behavior of GFRP bars is characterized by a linear elastic stress–strain relationship up to failure and, therefore, concrete elements reinforced with GFRP reinforcement exhibit brittle failure without warning. Design codes encourage over-reinforced GFRP design since it is more progressive and leads to a less catastrophic failure with a higher degree of deformability. Moreover, because of GFRP low modulus of elasticity, GFRP reinforced concrete members exhibit larger deflections and wider cracks width than steel reinforced concrete. This aims of this paper is to developed 2D Finite Element (FE models that can accurately simulate the respond on an improvement in the deflection of GFRP reinforced concrete beam externally strengthened with CFRP plates on the tension part of beam. The prediction of flexural response according to RCCSA software was also discussed. It was observed that the predicted FE results are given similar result with the experimental measured test data. Base on this good agreement, a parametric study was the performed using the validation FE model to investigate the effect of flexural reinforcement ratio and arrangement of the beams strengthened with different regions of CFRP plates.
A layer-wise MITC9 finite element for the free-vibration analysis of plates with piezo-patches
Directory of Open Access Journals (Sweden)
Maria Cinefra
2015-04-01
Full Text Available The present article considers the free-vibration analysis of plate structures with piezoelectric patches by means of a plate finite element with variable through-the-thickness layer-wise kinematic. The refined models used are derived from Carrera’s Unified Formulation (CUF and they permit the vibration modes along the thickness to be accurately described. The finite-element method is employed and the plate element implemented has nine nodes, and the mixed interpolation of tensorial component (MITC method is used to contrast the membrane and shear locking phenomenon. The related governing equations are derived from the principle of virtual displacement, extended to the analysis of electromechanical problems. An isotropic plate with piezoelectric patches is analyzed, with clamped-free boundary conditions and subjected to open- and short-circuit configurations. The results, obtained with different theories, are compared with the higher-order type solutions given in the literature. The conclusion is reached that the plate element based on the CUF is more suitable and efficient compared to the classical models in the study of multilayered structures embedding piezo-patches.
Institute of Scientific and Technical Information of China (English)
Xiao-ping Xie
2004-01-01
By following the geometric point of view in mechanics, a novel expression of the combined hybrid method for plate bending problems is introduced to clarify its intrinsic mechanism of enhancing coarse-mesh accuracy of conforming or nonconforming plate elements.By adjusting the combination parameter α∈ (0, 1) and adopting appropriate bending moments modes, reduction of energy error for the discretized displacement model leads to enhanced numerical accuracy. As an application, improvement of Adini's rectangle is discussed. Numerical experiments show that the combined hybrid counterpart of Adini's element is capable of attaining high accuracy at coarse meshes.
Directory of Open Access Journals (Sweden)
2009-11-01
Full Text Available This paper has investigated theoretically the influence of sliding speed and temperature on the hysteretic friction in case of a smooth, reciprocating steel ball sliding on smooth rubber plate by finite element method (FEM. Generalized Maxwell-models combined with Mooney-Rivlin model have been used to describe the material behaviour of the ethylenepropylene-diene-monomer (EPDM rubber studied. Additionally, the effect of the technique applied at the parameter identification of the material model and the number of Maxwell elements on the coefficient of friction (COF was also investigated. Finally, the open parameter of the Greenwood-Tabor analytical model has been determined from a fit to the FE results. By fitting, as usual, the Maxwell-model to the storage modulus master curve the predicted COF, in a broad frequency range, will be underestimated even in case of 40-term Maxwell-model. To obtain more accurate numerical prediction or to provide an upper limit for the hysteretic friction, in the interesting frequency range, the Maxwell parameters should be determined, as proposed, from a fit to the measured loss factor master curve. This conclusion can be generalized for all the FE simulations where the hysteresis plays an important role.
Finite element reduction strategy for composite sandwich plates with viscoelastic layers
Directory of Open Access Journals (Sweden)
Adriana Amaro Diacenco
2013-04-01
Full Text Available Composite materials have been regarded as a convenient strategy in various types of engineering systems such as aeronautical and space structures, as well as architecture and light industry products due to their advantages over the traditional engineering materials, such as their high strength/stiffness relation characteristics and their anti-corrosion properties. This paper is devoted to the finite element modeling of composite laminated structures incorporating viscoelastic materials to the problem of vibration attenuation. However, the typically high dimension of large finite element models of composite structures incorporating viscoelastic materials makes the numerical processes sometimes unfeasible. Within this context, emphasis is placed on a general condensation strategy specially adapted for the case of viscoelastically damped structures, in which a constant (frequency- and temperature-independent reduction basis to be enriched by static residues associated to the applied loads and the viscoelastic forces is used. After presenting the theoretical foundations, the numerical applications of composite plates treated by viscoelastic materials are addressed, and the main features of the methodology are discussed.
Finite element reduction strategy for composite sandwich plates with viscoelastic layers
Directory of Open Access Journals (Sweden)
Adriana Amaro Diacenco
2012-01-01
Full Text Available Composite materials have been regarded as a convenient strategy in various types of engineering systems such as aeronautical and space structures, as well as architecture and light industry products due to their advantages over the traditional engineering materials, such as their high strength/stiffness relation characteristics and their anti-corrosion properties. This paper is devoted to the finite element modeling of composite laminated structures incorporating viscoelastic materials to the problem of vibration attenuation. However, the typically high dimension of large finite element models of composite structures incorporating viscoelastic materials makes the numerical processes sometimes unfeasible. Within this context, emphasis is placed on a general condensation strategy specially adapted for the case of viscoelastically damped structures, in which a constant (frequency- and temperature-independent reduction basis to be enriched by static residues associated to the applied loads and the viscoelastic forces is used. After presenting the theoretical foundations, the numerical applications of composite plates treated by viscoelastic materials are addressed, and the main features of the methodology are discussed.
Numerical simulation of two-dimensional spouted bed with draft plates by discrete element method
Institute of Scientific and Technical Information of China (English)
Yongzhi ZHAO; Yi CHENG; Maoqiang JIANG; Yong JIN
2008-01-01
A discrete element method (DEM)-computa-tional fluid dynamics (CFD) two-way coupling method was employed to simulate the hydrodynamics in a two-dimensional spouted bed with draft plates. The motion of particles was modeled by the DEM and the gas flow was modeled by the Navier-Stokes equation. The interactions between gas and particles were considered using a two-way coupling method. The motion of particles in the spouted bed with complex geometry was solved by com-bining DEM and boundary element method (BEM). The minimal spouted velocity was obtained by the BEM-DEM-CFD simulation and the variation of the flow pat-tern in the bed with different superficial gas velocity was studied. The relationship between the pressure drop of the spouted bed and the superficial gas velocity was achieved from the simulations. The radial profile of the averaged vertical velocities of particles and the profile of the aver-aged void fraction in the spout and the annulus were stat-istically analyzed. The flow characteristics of the gas-solid system in the two-dimensional spouted bed were clearly described by the simulation results.
Static analysis of reinforced thin-walled plates and shells by means of finite element models
Carrera, E.; Zappino, E.; Cavallo, T.
2016-03-01
In this paper, variable kinematic one-dimensional (1D) structural models have been used to analyze thin-walled structures with longitudinal stiffeners and static loads. These theories have hierarchical features and are based on the Carrera Unified Formulation (CUF). CUF describes the displacement field of a slender structure as the product of two function expansions, one over the cross-sectional coordinates, Taylor (TE) or Lagrange (LE) expansions were used here, and one along the beam axis. The results obtained using the refined 1D models have been compared with those from classical finite element analyses that make use of plates/shells and solids elements. The performances of classical and refined structural models have been compared in terms of accuracy and computational costs. The results show that the use of the LE over the cross-section allows the strain/stress fields to be evaluated accurately for all the structural components. The comparisons with the results obtained using the classical models highlight how, the use of 1D refined models, allows the number of degrees of freedom (DOF) to be reduced, meanwhile, the accuracy of the results can be preserved.
Hollow waveguide cavity ringdown spectroscopy
Dreyer, Chris (Inventor); Mungas, Greg S. (Inventor)
2012-01-01
Laser light is confined in a hollow waveguide between two highly reflective mirrors. This waveguide cavity is used to conduct Cavity Ringdown Absorption Spectroscopy of loss mechanisms in the cavity including absorption or scattering by gases, liquid, solids, and/or optical elements.
Phonon waveguides for electromechanical circuits
Hatanaka, D.; Mahboob, I.; Onomitsu, K.; Yamaguchi, H.
2014-07-01
Nanoelectromechanical systems (NEMS), utilizing localized mechanical vibrations, have found application in sensors, signal processors and in the study of macroscopic quantum mechanics. The integration of multiple mechanical elements via electrical or optical means remains a challenge in the realization of NEMS circuits. Here, we develop a phonon waveguide using a one-dimensional array of suspended membranes that offers purely mechanical means to integrate isolated NEMS resonators. We demonstrate that the phonon waveguide can support and guide mechanical vibrations and that the periodic membrane arrangement also creates a phonon bandgap that enables control of the phonon propagation velocity. Furthermore, embedding a phonon cavity into the phonon waveguide allows mobile mechanical vibrations to be dynamically switched or transferred from the waveguide to the cavity, thereby illustrating the viability of waveguide-resonator coupling. These highly functional traits of the phonon waveguide architecture exhibit all the components necessary to permit the realization of all-phononic NEMS circuits.
Matuszyk, Paweł J.
2017-01-01
The circumferential guided waves (CGW) are of increasing interest for non-destructive inspecting pipes or other cylindrical structures. If such structures are buried underground, these modes can also deliver some valuable information about the surrounding medium or the quality of the contact between the pipe and the embedding medium. Toward this goal, the detailed knowledge of the dispersive characteristics of CGW is required; henceforth, the robust numerical method has to be established, which allows for the extensive study of the propagation of these modes under different loading conditions. Mathematically, this is the problem of the propagation of guided waves in an open waveguide. This problem differs significantly from the corresponding problem of a closed waveguide both in physical and numerical aspect. The paper presents a combination of semi-analytical finite element method with Perfectly Matched Layer technique for a class of coupled acoustics/elasticity problems with application to modeling of CGW. We discuss different aspects of our algorithm and validate the proposed approach against other established methods available in the literature. The presented numerical examples positively verify the robustness of the proposed method.
Simulation of irradiation hardening of Zircaloy within plate-type dispersion nuclear fuel elements
Jiang, Yijie; Wang, Qiming; Cui, Yi; Huo, Yongzhong; Ding, Shurong
2011-06-01
Within plate-type dispersion nuclear fuel elements, the metal matrix and cladding attacked continuously by fast neutrons undergo irradiation hardening, which might have remarkable effects upon the mechanical behaviors within fuel elements. In this paper, with the irradiation hardening effect of metal materials mainly considered together with irradiation growth effect of the cladding, the three-dimensional large-deformation constitutive relations for the metal matrix and cladding are developed. The method of virtual temperature increase in the previous studies is further developed to model the irradiation swelling of fuel particles; the method of anisotropic thermal expansion is introduced to model irradiation growth of the cladding; and a method of multi-step-temperature loading is proposed to simulate the coupling features of irradiation-induced swelling of the fuel particles together with irradiation growth of the cladding. Above all, based on the developed relationship between irradiation growth at certain burnup and the loaded virtual temperatures, with considering that certain burnup corresponds to certain fast neutron fluence, the time-dependent constitutive relation due to irradiation hardening effect is replaced by the virtual-temperature-dependent one which is introduced into the commercial software to simulate the irradiation hardening effects of the matrix and cladding. Numerical simulations of the irradiation-induced mechanical behaviors are implemented with the finite element method in consideration of the micro-structure of the fuel meat. The obtained results indicate that when the irradiation hardening effects are introduced into the constitutive relations of the metal matrix and cladding: (1) higher maximum Mises stresses for certain burnup at the matrix exist with the equivalent plastic strains remaining almost the same at lower burnups; (2) the maximum Mises stresses for certain burnup at the cladding are enhanced while the maximum equivalent
Directory of Open Access Journals (Sweden)
Jae S. Ahn
2014-01-01
Full Text Available The high-order layerwise element models have been used for damaged plates and shells in the presence of singularities such as crack, cutout, and delamination. In this study, the extension of a proposed finite element model has been tested for free vibration analysis of composite laminated systems. For the elements, three-dimensional displacement fields can be captured by layer-by-layer representation. For the elements, higher-order shape functions are derived by combination of one- and two-dimensional shape functions based on higher-order Lobatto shape functions, not using pure higher-order three-dimensional shape functions. The present model can relieve difficulty of aspect ratios in modeling very thin thickness of bonding layer. For verification of the model, natural frequencies and corresponding mode shapes are calculated and then compared with reference values for uncracked and cracked plates. Also, the vibration characteristics of one-sided patch repaired plates with a through internal crack are investigated with respect to variation of crack length, size and thickness of patch, and shear modulus of adhesive, respectively.
Directory of Open Access Journals (Sweden)
A. E. Alshorbagy
2013-01-01
Full Text Available The first-order shear deformation plate model, accounting for the exact neutral plane position, is exploited to investigate the uncoupled thermomechanical behavior of functionally graded (FG plates. Functionally graded materials are mainly constructed to operate in high temperature environments. Also, FG plates are used in many applications (such as mechanical, electrical, and magnetic, where an amount of heat may be generated into the FG plate whenever other forms of energy (electrical, magnetic, etc. are converted into thermal energy. Several simulations are performed to study the behavior of FG plates, subjected to thermomechanical loadings, and focus the attention on the effect of the heat source intensity. Most of the previous studies have considered the midplane neutral one, while the actual position of neutral plane for functionally graded plates is shifted and should be firstly determined. A comparative study is performed to illustrate the effect of considering the neutral plane position. The volume fraction of the two constituent materials of the FG plate is varied smoothly and continuously, as a continuous power function of the material position, along the thickness of the plate.
Directory of Open Access Journals (Sweden)
V. Srinivasa Rao
2013-01-01
Full Text Available The objectives of the present study are to investigate the radiation effects on unsteady heat and mass transfer flow of a chemically reacting fluid past a semi-infinite vertical plate with viscous dissipation. The method of solution is applied using Finite element technique. Numerical results for the velocity, the temperature and the concentration are shown graphically for various flow parameters. The expressions for the skin-frication, Nusselt number and Sherwood number are obtained. The result shows that increased cooling (Gr>0 of the plate and the Eckert number leads to a rise in the velocity. Also, an increase in the Eckert number leads to an increase in the temperature, whereas increase in radiation lead to a decrease in the temperature distribution when the plate is being cooled.
Mei, Chuh
1987-01-01
A finite element method is presented for the large amplitude vibrations of complex structures that can be modelled with beam and rectangular plate elements subjected to harmonic excitation. Both inplane deformation and inertia are considered in the formulation. Derivation of the harmonic force and nonlinear stiffness matrices for a beam and a rectangular plate element are presented. Solution procedures and convergence characteristics of the finite element method are described. Nonlinear response to uniform and concentrated harmonic loadings and improved nonlinear free vibration results are presented for beams and rectangular plates of various boundary conditions.
Karimi, Hossein; Nikmehr, Saeid; Khodapanah, Ehsan
2016-09-01
In this paper, we develop a B-spline finite-element method (FEM) based on a locally modal wave propagation with anisotropic perfectly matched layers (PMLs), for the first time, to simulate nonlinear and lossy plasmonic waveguides. Conventional approaches like beam propagation method, inherently omit the wave spectrum and do not provide physical insight into nonlinear modes especially in the plasmonic applications, where nonlinear modes are constructed by linear modes with very close propagation constant quantities. Our locally modal B-spline finite element method (LMBS-FEM) does not suffer from the weakness of the conventional approaches. To validate our method, first, propagation of wave for various kinds of linear, nonlinear, lossless and lossy materials of metal-insulator plasmonic structures are simulated using LMBS-FEM in MATLAB and the comparisons are made with FEM-BPM module of COMSOL Multiphysics simulator and B-spline finite-element finite-difference wide angle beam propagation method (BSFEFD-WABPM). The comparisons show that not only our developed numerical approach is computationally more accurate and efficient than conventional approaches but also it provides physical insight into the nonlinear nature of the propagation modes.
Directory of Open Access Journals (Sweden)
Abdulrahman Al-Ahmari
2015-07-01
Full Text Available Mandible defects and its deformities are serious complications and its precise reconstruction is one of the most challenging tasks in oral maxillofacial surgery. The commercially available standard mandible implants are manually bended before surgery to custom fit the patient’s jaw. A slight mismatch in the plate and bone alignment may result in the implant failure. However, with the integration of computer-aided design, rapid prototyping, and advanced imaging systems (computed tomography or magnetic resonance imaging, it is possible to produce a customized mandible implant that can precisely fit the patient’s jaw. The aim of this article is to compare a new design of customized mandible implant (sinewave plate and compare it with the commonly used straight implant design. The finite element–simulated results reveal that the commonly used straight reconstruction plates are more prone to loosening of the screws due to its higher strain concentration on the screw hole when compared to newly designed sinewave reconstruction plate. Moreover, the straight plate is more sensitive to the chewing load variations and develops almost 20% increase in the stresses when compared to sinewave plate. The study reveals that the sinewave reconstruction plate can significantly enhance the stability and safety of the mandible implant.
Ponchak, George E.
1999-01-01
Researchers in NASA Lewis Research Center s Electron Device Technology Branch are developing transmission lines for radiofrequency and wireless circuits that are more efficient, smaller, and make lower cost circuits possible. Traditionally, radiofrequency and wireless circuits have employed a microstrip or coplanar waveguide to interconnect the various electrical elements that comprise a circuit. Although a coplanar waveguide (CPW) is widely viewed as better than a microstrip for most applications, it too has problems. To solve these problems, NASA Lewis and the University of Michigan developed a new version of a coplanar waveguide with electrically narrow ground planes. Through extensive numerical modeling and experimental measurements, we have characterized the propagation constant of the FGC waveguide, the lumped and distributed circuit elements integrated in the FGC waveguide, and the coupling between parallel transmission lines. Although the attenuation per unit length is higher for the FGC waveguide because of higher conductor loss, the attenuation is comparable when the ground plane width is twice the center conductor width as shown in the following graph. An upper limit to the line width is derived from observations that when the total line width is greater than ld/2, spurious resonances due to the parallel plate waveguide mode are established. Thus, the ground plane width must be less than ld/4 where ld is the wavelength in the dielectric. Since the center conductor width S is typically less than l/10 to maintain good transverse electromagnetic mode characteristics, it follows that a ground plane width of B = 2S would also be electrically narrow. Thus, we can now treat the ground strips of the FGC waveguide the same way that the center conductor is treated.
Impact Of Screen Ruling on the Formation of the Printing Elements on the Flexographic Printing Plate
National Research Council Canada - National Science Library
Tamara Tomašegović; Sanja Mahović Poljaček; Tomislav Cigula
2012-01-01
Flexography is a printing technique widely used in the packaging production. The main feature of the flexography is the usage of the printing plate which is elastically deformed during the reproduction process...
Impact Of Screen Ruling on the Formation of the Printing Elements on the Flexographic Printing Plate
National Research Council Canada - National Science Library
Tamara Tomašegović; Sanja Mahović Poljaček; Tomislav Cigula
2013-01-01
Flexography is a printing technique widely used in the packaging production. The main feature of the flexography is the usage of the printing plate which is elastically deformed during the reproduction process...
Rahman, T.; IJsselmuiden, S.T.; Abdalla, M.M.; Jansen, E.L.
2011-01-01
Modern fiber placement machines allow laminates with spatially varying stiffness properties to be manufactured. In earlier research, the authors optimized variable stiffness plates for maximum buckling load, demonstrating significant improvements in load-carrying capacity. In aerospace applications,
Energy Technology Data Exchange (ETDEWEB)
Zuo, Peng; Fan, Zheng, E-mail: ZFAN@ntu.edu.sg [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Zhou, Yu [Advanced Remanufacturing and Technology Center (ARTC), 3 Clean Tech Loop, CleanTech Two, Singapore 637143 (Singapore)
2016-07-15
Nonlinear guided waves have been investigated widely in simple geometries, such as plates, pipe and shells, where analytical solutions have been developed. This paper extends the application of nonlinear guided waves to waveguides with arbitrary cross sections. The criteria for the existence of nonlinear guided waves were summarized based on the finite deformation theory and nonlinear material properties. Numerical models were developed for the analysis of nonlinear guided waves in complex geometries, including nonlinear Semi-Analytical Finite Element (SAFE) method to identify internal resonant modes in complex waveguides, and Finite Element (FE) models to simulate the nonlinear wave propagation at resonant frequencies. Two examples, an aluminum plate and a steel rectangular bar, were studied using the proposed numerical model, demonstrating the existence of nonlinear guided waves in such structures and the energy transfer from primary to secondary modes.
Plasmonic Antennas Hybridized with Dielectric Waveguides
Arango, Felipe Bernal; Koenderink, A Femius
2013-01-01
For the purpose of using plasmonics in an integrated scheme where single emitters can be probed efficiently, we experimentally and theoretically study the scattering properties of single nano-rod gold antennas as well as antenna arrays placed on one-dimensional dielectric silicon nitride waveguides. Using real space and Fourier microscopy correlated with waveguide transmission measurements, we quantify the spectral properties, absolute strength and directivity of scattering. The scattering processes can be well understood in the framework of the physics of dipolar objects placed on a planar layered environment with a waveguiding layer. We use the single plasmonic structures on top of the waveguide as dipolar building blocks for new types of antennas where the waveguide enhances the coupling between antenna elements. We report on waveguide hybridized Yagi-Uda antennas which show directionality in out-coupling of guided modes as well as directionality for in-coupling into the waveguide of localized excitations ...
Homogenization analysis of complementary waveguide metamaterials
Landy, Nathan; Hunt, John; Smith, David R.
2013-11-01
We analyze the properties of complementary metamaterials as effective inclusions patterned into the conducting walls of metal waveguide structures. We show that guided wave metamaterials can be homogenized using the same retrieval techniques used for volumetric metamaterials, leading to a description in which a given complementary element is conceptually replaced by a block of material within the waveguide whose effective permittivity and permeability result in equivalent scattering characteristics. The use of effective constitutive parameters for waveguide materials provides an alternative point-of-view for the design of waveguide and microstrip based components, including planar lenses and filters, as well as devices with derived from a bulk material response. In addition to imparting effective constitutive properties to the waveguide, complementary metamaterials also couple energy from waveguide modes into radiation. Thus, complementary waveguide metamaterials can be used to modify and optimize a variety of antenna structures.
Indian Academy of Sciences (India)
Gajbir Singh; G Venkateswara Rao
2000-08-01
The objective of the present paper is to investigate the large amplitude vibratory behaviour of unsymmetrically laminated plates. For this purpose, an efficient and accurate four-node shear flexible rectangular material finite element(MFE) with six degrees offreedom per node (three displacements $(u;v;w)$ along the $x, y$ and axes, two rotations ($\\theta_x$ and $\\theta_y$) about and axes and twist $(\\theta_{xy})$) is developed. The element assumes bi-cubic polynomial distribution with sixteen generalized undetermined coefficients for the transverse displacement. The fields for section rotations $\\theta_x$ and $\\theta_y$, and in-plane displacements and are derived using moment-shear equilibrium and in-plane equilibrium equations of composite strips along the - and -axes. The displacement field so derived not only depends on the element coordinates but is a function of extensional, bending-extensional coupling, bending and transverse shear stiffness as well. The element stiffness and mass matrices are computed numerically by employing 3 × 3 Gauss-Legendre product rules. The element is found to be free of shear locking and does not exhibit any spurious modes. In orderto compute the nonlinearfrequencies, linear mode shape corresponding to the fundamental frequency is assumed as the spatial distribution and nonlinear finite element equations are reduced to a single nonlinear second-order differential equation. This equation is solved by employing the direct numerical integration method. A series of numerical examples are solved to demonstrate the efficacy of the proposed element.
Energy Technology Data Exchange (ETDEWEB)
Venkatkumar, D.; Ravindran, D. [National Engineering College, Tamilnadu (India)
2016-01-15
In the present study, the distortion induced in rectangular plate of AISI 304 SS during autogenous GTA welding process is measured experimentally and further validated using Finite element (FE) analysis. The thermal histories are measured at fixed locations over the surface of the plate and the results are compared with FE analysis. The Gaussian surface and Volumetric heat source models are simulated and transient heat transfer analysis is performed. The heat source models have been tested with two different speeds. The effectiveness of change in thermal histories of the heat sources have been studied and reported. In FE analysis, the sequentially coupled thermomechanical analysis is performed using the thermal histories as input and the distortion of the plates are predicted and compared with experimental measurements. The large and small displacement theories are employed for the above purpose and the effectiveness of the theories are reported. The edge deformation of the plates have been measured and validated for both the theories. The residual stress and distortion at the mid span are predicted and discussed. The results predicted using large displacement theory is in good agreement with measured values.
Institute of Scientific and Technical Information of China (English)
Zhang Yong; Yang Jianguo; Liu Xuesong; Fang Hongyuan
2010-01-01
The new technology of welding with impacting rotation is put forward to decrease the wave-like deformation of the TC4 thin plate weldment.The thermal stress and strain are vital to understand the mechanism of controlling the wave-like deformation.In order to know the development of internal thermal stress and strain,finite element method is utilized for the stress and strain are difficult to be investigated by experimental methods during the welding process.Temperature field,thermal stress evolution and distortion of thin plate are compared with the test results such as weld thermal cycle,residual stress sectioning measurement,and the deflection of the thin plate respectively.By the finite element analysis and test results verification,the mechanism of the technology to control the wave-like deformation is brought forward,non-uniform thermal elastic strain between compressive plastic region and elastic extensive region is diminished by a certain amount of extensive plastic deformation by welding with impacting rotation process.
Wave-guided optical waveguides
DEFF Research Database (Denmark)
Palima, Darwin; Bañas, Andrew Rafael; Vizsnyiczai, George
2012-01-01
This work primarily aims to fabricate and use two photon polymerization (2PP) microstructures capable of being optically manipulated into any arbitrary orientation. We have integrated optical waveguides into the structures and therefore have freestanding waveguides, which can be positioned anywhe...... bridge the diffraction barrier. This structure-mediated paradigm may be carried forward to open new possibilities for exploiting beams from far-field optics down to the subwavelength domain....
Lamb wave band gaps in locally resonant phononic crystal strip waveguides
Energy Technology Data Exchange (ETDEWEB)
Yao, Yuanwei, E-mail: yaoyw@scut.edu.cn [Department of Physics, Guangdong University of Technology, Guangzhou 510006 (China); Wu, Fugen [Experiment and Educational Center, Guangdong University of Technology, Guangzhou 510006 (China); Zhang, Xin [Department of Physics, Guangdong University of Technology, Guangzhou 510006 (China); Hou, Zhilin [Department of Physics, South China University of Technology, Guangzhou 510640 (China)
2012-01-09
Using finite element method, we have made a theoretically study of the band structure of Lamb wave in a locally resonant phononic crystal strip waveguide with periodic soft rubber attached on the two sides of epoxy main plate. The numerical results show that the Lamb wave band gap based on local resonant mechanism can be opened up in the stub strip waveguides, and the width of the local resonant band gap is narrower than that based on the Bragg scattering mechanism. The results also show that the stub shape and width have influence on the frequency and width of the Lamb wave band gap. -- Highlights: ► The local resonant Lamb wave band gap can be opened up in a stub strip waveguides. ► The width of the local resonant band gap is narrower than that Bragg scattering band gap. ► The shape and width of the stub have strongly influence on the local resonant band gap.
Quasi-optimal locations of piezo-elements on a rectangular plate
Koszewnik, Andrzej; Gosiewski, Zdzisław
2016-07-01
The optimal location of piezo-actuators and piezo-sensors for the vibration control of a rectangular plate with SFSF (Simply Supported - Free - Simply Supported - Free) boundary conditions is presented in the paper. Based on bending moments, Mx(x,y) and My(x,y), the modal control forces generated by the piezo-stripes are calculated for the first five mode shapes. Calculations are carried out for different locations of two piezo-strips directed along the X and Y axes. The obtained results are used to define performance indexes of modal control forces for the two considered directions of vibration. In a similar way the modal unit elongations of the piezo-sensors are calculated for two different orientations of the piezos on the plate. Based on these results the objective cost functions J_{ɛ - odd} and J_{ɛ - even} are defined separately for odd and even modes. The quasi-optimal locations of the piezo-actuators and piezo-sensors are determined by maximizing the proposed cost functions. After analytical and numerical investigations the process of the full model identification is carried out at the laboratory stand. A chirp signal is applied in the identification process. The rectangular plate is excited with the chirp force while output signals are measured by the piezo-sensors oriented in the perpendicular directions X and Y. In such a way two mathematical models are obtained to control the vibration of the plate separately for odd and even natural modes.-1
On Choices of Stress Modes for Lower Order Quadrilateral Reissner-Mindlin Plate Elements
Institute of Scientific and Technical Information of China (English)
Guanghui Hu; Xiaoping Xie
2006-01-01
A kind of stabilized mixed/hybrid scheme for Reissner-Mindlin plates is proposed with conforming isoparametric bilinear interpolations of deflection/rotations. The choice of shear stress modes is discussed. It is shown by numerical experiments that fulfilling an energy orthogonal condition for stress approximations is crucial to avoiding "shear locking".
Reddy, J. N.
1986-01-01
An improved plate theory that accounts for the transverse shear deformation is presented, and mixed and displacement finite element models of the theory are developed. The theory is based on an assumed displacement field in which the inplane displacements are expanded in terms of the thickness coordinate up to the cubic term and the transverse deflection is assumed to be independent of the thickness coordinate. The governing equations of motion for the theory are derived from the Hamilton's principle. The theory eliminates the need for shear correction factors because the transverse shear stresses are represented parabolically. A mixed finite element model that uses independent approximations of the displacements and moments, and a displacement model that uses only displacements as degrees of freedom are developed. A comparison of the numerical results for bending with the exact solutions of the new theory and the three-dimensional elasticity theory shows that the present theory (and hence the finite element models) is more accurate than other plate-theories of the same order.
Shamshuddin, MD.; Anwar Bég, O.; Sunder Ram, M.; Kadir, A.
2017-08-01
Non-Newtonian flows arise in numerous industrial transport processes including materials fabrication systems. Micropolar theory offers an excellent mechanism for exploring the fluid dynamics of new non-Newtonian materials which possess internal microstructure. Magnetic fields may also be used for controlling electrically-conducting polymeric flows. To explore numerical simulation of transport in rheological materials processing, in the current paper, a finite element computational solution is presented for magnetohydrodynamic, incompressible, dissipative, radiative and chemically-reacting micropolar fluid flow, heat and mass transfer adjacent to an inclined porous plate embedded in a saturated homogenous porous medium. Heat generation/absorption effects are included. Rosseland's diffusion approximation is used to describe the radiative heat flux in the energy equation. A Darcy model is employed to simulate drag effects in the porous medium. The governing transport equations are rendered into non-dimensional form under the assumption of low Reynolds number and also low magnetic Reynolds number. Using a Galerkin formulation with a weighted residual scheme, finite element solutions are presented to the boundary value problem. The influence of plate inclination, Eringen coupling number, radiation-conduction number, heat absorption/generation parameter, chemical reaction parameter, plate moving velocity parameter, magnetic parameter, thermal Grashof number, species (solutal) Grashof number, permeability parameter, Eckert number on linear velocity, micro-rotation, temperature and concentration profiles. Furthermore, the influence of selected thermo-physical parameters on friction factor, surface heat transfer and mass transfer rate is also tabulated. The finite element solutions are verified with solutions from several limiting cases in the literature. Interesting features in the flow are identified and interpreted.
Condie, Kent C.; Shearer, Charles K.
2017-09-01
The distribution of high field strength incompatible element ratios Zr/Nb, Nb/Th, Th/Yb and Nb/Yb in terrestrial oceanic basalts prior to 2.7 Ga suggests the absence or near-absence of an enriched mantle reservoir. Instead, most oceanic basalts reflect a variably depleted mantle source similar in composition to primitive mantle. In contrast, basalts from hydrated mantle sources (like those associated with subduction) exist from 4 Ga onwards. The gradual appearance of enriched mantle between 2 and 3 Ga may reflect the onset and propagation of plate tectonics around the globe. Prior to 3 Ga, Earth may have been in a stagnant-lid regime with most basaltic magmas coming from a rather uniform, variably depleted mantle source or from a non-subduction hydrated mantle source. It was not until the extraction of continental crust and accompanying propagation of plate tectonics that ;modern type; enriched and depleted mantle reservoirs developed. Consistent with the absence of plate tectonics on the Moon is the near absence of basalts derived from depleted (DM) and enriched (EM) mantle reservoirs as defined by the four incompatible element ratios of this study. An exception are Apollo 17 basalts, which may come from a mixed source with a composition similar to primitive mantle as one end member and a high-Nb component as the other end member. With exception of Th, which requires selective enrichment in at least parts of the martian mantle, most martian meteorites can be derived from sources similar to terrestrial primitive mantle or by mixing of enriched and depleted mantle end members produced during magma ocean crystallization. Earth, Mars and the Moon exhibit three very different planetary evolution paths. The mantle source regions for Mars and the Moon are ancient and have HFS element signatures of magma ocean crystallization well-preserved, and differences in these signatures reflect magma ocean crystallization under two distinct pressure regimes. In contrast, plate
Lee, Cheng-Hung; Shih, Cheng-Min; Huang, Kui-Chou; Chen, Kun-Hui; Hung, Li-Kun; Su, Kuo-Chih
2016-11-01
Clinical implantation of clavicle hook plates is often used as a treatment for acromioclavicular joint dislocation. However, it is not uncommon to find patients that have developed acromion osteolysis or had peri-implant fracture after hook plate fixation. With the aim of preventing complications or fixation failure caused by implantation of inappropriate clavicle hook plates, the present study investigated the biomechanics of clavicle hook plates made of different materials and with different hook depths in treating acromioclavicular joint dislocation, using finite element analysis (FEA). This study established four parts using computer models: the clavicle, acromion, clavicle hook plate, and screws, and these established models were used for FEA. Moreover, implantations of clavicle hook plates made of different materials (stainless steel and titanium alloy) and with different depths (12, 15, and 18 mm) in patients with acromioclavicular joint dislocation were simulated in the biomechanical analysis. The results indicate that deeper implantation of the clavicle hook plate reduces stress on the clavicle, and also reduces the force applied to the acromion by the clavicle hook plate. Even though a clavicle hook plate made of titanium alloy (a material with a lower Young's modulus) reduces the force applied to the acromion by the clavicle hook plate, slightly higher stress on the clavicle may occur. The results obtained in this study provide a better reference for orthopedic surgeons in choosing different clavicle hook plates for surgery. Copyright © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.
A New Accurate yet Simple Shear Flexible Triangular Plate Element with Linear Bending Strains
DEFF Research Database (Denmark)
Damkilde, Lars; Pedersen, Ronnie
2010-01-01
The paper describes a new shear flexible triangular element. The formulation is based on displacement interpolation of the transverse displacement of the midsurface and the rotations of the cross-sections, and the element is fully compatible. The basic principle is to use a so-called balanced...
Finite Element Analysis of the Polyethylene Pipe Heating during Welding with a Heating Plate
Directory of Open Access Journals (Sweden)
Adelin Tută
2008-10-01
Full Text Available In this paper we present the results of a study based on the finite element method applied to end-to-end polyethylene pipe welding. In the experiment we used the ANSYS 6.1 finite element program that succeeds to accurately capture many common physical phenomena.
Cup Cylindrical Waveguide Antenna
Acosta, Roberto J.; Darby, William G.; Kory, Carol L.; Lambert, Kevin M.; Breen, Daniel P.
2008-01-01
The cup cylindrical waveguide antenna (CCWA) is a short backfire microwave antenna capable of simultaneously supporting the transmission or reception of two distinct signals having opposite circular polarizations. Short backfire antennas are widely used in mobile/satellite communications, tracking, telemetry, and wireless local area networks because of their compactness and excellent radiation characteristics. A typical prior short backfire antenna contains a half-wavelength dipole excitation element for linear polarization or crossed half-wavelength dipole elements for circular polarization. In order to achieve simultaneous dual circular polarization, it would be necessary to integrate, into the antenna feed structure, a network of hybrid components, which would introduce significant losses. The CCWA embodies an alternate approach that entails relatively low losses and affords the additional advantage of compactness. The CCWA includes a circular cylindrical cup, a circular disk subreflector, and a circular waveguide that serves as the excitation element. The components that make it possible to obtain simultaneous dual circular polarization are integrated into the circular waveguide. These components are a sixpost polarizer and an orthomode transducer (OMT) with two orthogonal coaxial ports. The overall length of the OMT and polarizer (for the nominal middle design frequency of 2.25 GHz) is about 11 in. (approximately equal to 28 cm), whereas the length of a commercially available OMT and polarizer for the same frequency is about 32 in. (approximately equal to 81 cm).
Directory of Open Access Journals (Sweden)
Y. Y. Lee
2012-01-01
Full Text Available An analytical quadrilateral p element is developed for solving the free vibrations of piezoelectric-laminated plates. The formulations of the displacement and strain fields are based on first-order shear deformation plate theory. The coupling effect between the electrical and stress fields is also considered. The Legendre orthogonal polynomials are used as the element interpolation functions, and the analytical integration technique is adopted. It is found that the present p element method gives high numerical precision results, fast and monotonic convergence rate. In the numerical cases, the effects of the number of hierarchical terms and mesh size on the convergence rate are investigated. Examples of square plates with different displacement and potential boundary conditions are studied. In the comparisons, the solutions of the present element are in good agreement with those obtained from other classical and finite element methods.
Energy Technology Data Exchange (ETDEWEB)
Rieben, R; White, D; Rodrigue, G
2004-01-13
In this paper we motivate the use of a novel high order time domain vector finite element method that is of arbitrary order accuracy in space and up to 5th order accurate in time; and in particular, we apply it to the case of photonic band-gap (PBG) structures. Such structures have been extensively studied in the literature with several practical applications; in particular, for the low loss transmission of electromagnetic energy around sharp 90 degree bends [1]. Typically, such structures are simulated via a numerical solution of Maxwell's equations either in the frequency domain or directly in the time domain over a computational grid. The majority of numerical simulations performed for such structures make use of the widely popular finite difference time domain (FDTD) method [2], where the time dependent electric and magnetic fields are discretized over a ''dual'' grid to second order accuracy in space and time. However, such methods do not generalize to unstructured, non-orthogonal grids or to higher order spatial discretization schemes. To simulate more complicated structures with curved boundaries, such as the structure of [3], a cell based finite element method with curvilinear elements is preferred over standard stair-stepped Cartesian meshes; and to more efficiently reduce the effects of numerical dispersion, a higher order method is highly desirable. In this paper, the high order basis functions of [5] are used in conjunction with the high order energy conserving symplectic time integration algorithms of [6] resulting in a high order, fully mimetic, mixed vector finite element method.
Institute of Scientific and Technical Information of China (English)
Wei Xia; Qiao Ni
2011-01-01
The influence of fiber orientation,flow yaw angle and length-to-thickness ratio on flutter characteristics of angle-ply laminated plates in supersonic flow is studied by finite element approach.The structural model is established using the Reissner-Mindlin theory in which the transverse shear deformation is considered.The aerodynamic pressure is evaluated by the quasi-steady first-order piston theory.The equations of motion are formulated based on the principle of virtual work.With the harmonic motion assumption,the flutter boundary is determined by solving a series of complex eigenvalue problems.Numerical study shows that (1)The flutter dynamic pressure and the coalescence of flutter modes depend on fiber orientation,flow yaw angle and length-to-thickness ratio; (2) The laminated plate with all fibers aligned with the flow direction gives the highest flutter dynamic pressure,but a slight yawing of the flow from the fiber orientation results in a sharp decrease of the flutter dynamic pressure; (3) The angle-ply laminated plate with fiber orientation angle equal to flow yaw angle gives high flutter dynamic pressure,but not the maximum flutter dynamic pressure; (4) With the decrease of length-to-thickness ratio,an adverse effect due to mode transition on the flutter dynamic pressure is found.
Energy Technology Data Exchange (ETDEWEB)
Hakan Ozaltun; Herman Shen; Pavel Madvedev
2010-11-01
This article presents numerical simulation of dispersion fuel mini plates via fluid–thermal–structural interaction performed by commercial finite element solver COMSOL Multiphysics to identify initial mechanical response under actual operating conditions. Since fuel particles are dispersed in Aluminum matrix, and temperatures during the fabrication process reach to the melting temperature of the Aluminum matrix, stress/strain characteristics of the domain cannot be reproduced by using simplified models and assumptions. Therefore, fabrication induced stresses were considered and simulated via image based modeling techniques with the consideration of the high temperature material data. In order to identify the residuals over the U7Mo particles and the Aluminum matrix, a representative SEM image was employed to construct a microstructure based thermo-elasto-plastic FE model. Once residuals and plastic strains were identified in micro-scale, solution was used as initial condition for subsequent multiphysics simulations at the continuum level. Furthermore, since solid, thermal and fluid properties are temperature dependent and temperature field is a function of the velocity field of the coolant, coupled multiphysics simulations were considered. First, velocity and pressure fields of the coolant were computed via fluidstructural interaction. Computed solution for velocity fields were used to identify the temperature distribution on the coolant and on the fuel plate via fluid-thermal interaction. Finally, temperature fields and residual stresses were used to obtain the stress field of the plates via fluid-thermal-structural interaction.
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
This paper discusses the validity of (adaptive) Lagrange generalized plain finite element method(FEM) and plate element method for accurate analysis of acoustic waves in multi-layered piezoelectric structures with tiny interfaces between metal electrodes and surface mounted piezoelectric substrates. We have come to conclusion that the quantitative relationships between the acoustic and electric fields in a piezoelectric structure can be accurately determined through the proposed finite element methods. The higher-order Lagrange FEM proposed for dynamic piezoelectric computation is proved to be very accurate (prescribed relative error 0.02%-0.04%) and a great improvement in convergence accuracy over the higher order Mindlin plate element method for piezoelectric structural analysis due to the assumptions and corrections in the plate theories. The converged Lagrange finite element methods are compared with the plate element methods and the computed results are in good agreement with available exact and experimental data. The adaptive Lagrange finite element methods and a new FEA computer program developed for macro- and micro-scale analyses are reviewed, and recently extended with great potential to high-precision nano-scale analysis in this paper and the similarities between piezoelectric and seismic wave propagations in layered structures and plates are stressed.
Asemi, K.; Ashrafi, H.; Shariyat, M.
2016-07-01
Static and free vibration analyses of plates with circular holes are performed based on the three-dimensional theory of elasticity. The plates are made of a functionally graded material (FGM), and the volume fractions of the constituent materials vary continuously across the plate. The effective properties of the FGM plate are estimated by using the Mori-Tanaka homogenization method. A graded finite element method based on the Rayleigh-Ritz energy formulation is used to solve the problem. Effects of different volume fractions of the materials and hole sizes on the behavior of FGM plates under uniaxial tension are investigated. Natural frequencies of a fully clamped FGM plate with a circular cutout are derived. The results obtained are compared with available experimental data.
Park, Myungsoon; Na, Yonghyun; Park, Minbong
2017-01-01
Objective The objective of this study was to analyze the patterns of tooth movements when distalization of mandibular molars using a mini-plate took place. A finite element analysis was applied to analyze patterns of tooth movements. Methods The model of the mandible and teeth were used to build a finite element analysis model, and a mini-plate was inserted in the mandibular ramus. Two different orthodontic forces were established for displacement of mandibular molars. Orthodontic forces were applied at the level of the bracket and at the level of the cemento-enamel junction in the mandibular canine respectively. Results orthodontic forces at the level of the cemento-enamel junction resulted in a greater biomechanical bodily movement in distalization of the mandibular molars compared to when the orthodontic forces were applied at the level of the bracket. Applying orthodontic forces to the cemento-enamel junction also resulted in unwanted greater extrusive movements in distalization of the mandibular molars compared to the bracket level. Conclusions With considering the mode of orthodontic teeth movement, applying different vertical orthodontic forces for distalization of mandibular molars can lead to more effective distalization of teeth. PMID:28861390
Annealing effects in plated-wire memory elements. II - Recrystallization in Permalloy films.
Marquardt, S. J.; Kench, J. R.
1971-01-01
Results of grain-size measurements in Permalloy platings suggest that recrystallization is possible at temperatures as low as 200 C, but that it is an extremely heterogeneous process. No worthwhile correlation was found to exist between observed grain size and magnetic dispersion in samples aged in the temperature range from 180 to 230 C. It is suggested that the magnetic aging which occurs under these conditions may be due to some other diffusion-controlled process than recrystallization; a process such as chemical homogenization is tentatively preferred.
Capillary waveguide optrodes for Medical applications
Kieslinger, Dietmar; Weigl, Bernhard H.; Draxler, Sonja; Lippitsch, Max E.
1997-01-01
Glass capillaries with a chemically sensitive coating on the inner surface are used as optical sensors for medical diagnostics. The capillary simultaneously serves as a sample compartment, a sensor element, and an inhomogeneous optical waveguide. Different optical setups have been investigated and compared regarding its waveguiding properties.
Directory of Open Access Journals (Sweden)
Douglas Rangel Goulart
2015-09-01
Full Text Available Objectives: The aim of the present study was to develop a plate to treat mandibular angle fractures using the finite element method and mechanical testing. Material and Methods: A three-dimensional model of a fractured mandible was generated using Rhinoceros 4.0 software. The models were exported to ANSYS®, in which a static application of displacement (3 mm was performed in the first molar region. Three groups were assessed according to the method of internal fixation (2 mm system: two non-locking plates; two locking plates and a new design locking plate. The computational model was transferred to an in vitro experiment with polyurethane mandibles. Each group contained five samples and was subjected to a linear loading test in a universal testing machine. Results: A balanced distribution of stress was associated with the new plate design. This plate modified the mechanical behavior of the fractured region, with less displacement between the fractured segments. In the mechanical test, the group with two locking plates exhibited greater resistance to the 3 mm displacement, with a statistically significant difference when compared with the new plate group (ANOVA, P = 0.016. Conclusions: The new plate exhibited a more balanced distribution of stress. However, the group with two locking plates exhibited greater mechanical resistance.
Microwave gas breakdown in elliptical waveguides
Energy Technology Data Exchange (ETDEWEB)
Koufogiannis, I. D.; Sorolla, E., E-mail: eden.sorolla@epfl.ch; Mattes, M. [École Polytechnique Fédérale de Lausanne, Laboratoire d’Électromagnétisme et d' Acoustique (LEMA), Station 11, CH-1015 Lausanne (Switzerland)
2014-01-15
This paper analyzes the microwave gas discharge within elliptical waveguides excited by the fundamental mode. The Rayleigh-Ritz method has been applied to solve the continuity equation. The eigenvalue problem defined by the breakdown condition has been solved and the effective diffusion length of the elliptical waveguide has been calculated, what is used to find the corona threshold. This paper extends the microwave breakdown model developed for circular waveguides and shows the better corona withstanding capabilities of elliptical waveguides. The corona breakdown electric field threshold obtained with the variational method has been compared with the one calculated with the Finite Elements Method, showing excellent agreement.
Institute of Scientific and Technical Information of China (English)
张武; 洪涛
2002-01-01
This paper discusses the validity of (adaptive) Lagrange generalized plain finite element method (FEM) and plate element method for accurate analysis of acoustic waves in multi-layered piezoelectric structures with tiny interfaces between metal electrodes and surface mounted piezoelectric substrates. We have come to conclusion that the quantitative relationships between the acoustic and electric fields in a piezoelectric structure can be accurately determined through the proposed finite element methods. The higher-order Lagrange FEM proposed for dynamic piezoelectric computation is proved to be very accurate (prescribed relative error 0.02% - 0.04% ) and a great improvement in convergence accuracy over the higher order Mindlin plate element method for piezoelectric structural analysis due to the assumptions and corrections in the plate theories.The converged lagrange finite element methods are compared with the plate element methods and the computedresults are in good agreement with available exact and experimental data. The adaptive Lagrange finite elementmethods and a new FEA computer program developed for macro- and micro-scale analyses are reviewed, and recently extended with great potential to high-precision nano-scale analysis in this paper and the similarities between piezoelectric and seismic wave propagations in layered structures and plates are stressed.
The upgrade and conversion of the ET-RR-1 research reactor using plate type fuel elements
Energy Technology Data Exchange (ETDEWEB)
Ashoub, N. [Reactor Physics Dept., Nuclear Research Center, Atomic Energy Authority, Cairo (Egypt); Saleh, H.G. [Faculty of Girls for Arts and Education, Ain-Shams Univ., Cairo (Egypt)
2001-11-01
The ET-RR-1 research reactor has been operated at 2 MW since 1961 using EK-10 fuel elements with 10% enriched uranium. The reactor has been used for nuclear applied research and isotope production. In order to upgrade the reactor power to a reasonable limit facing up-to-date uses, core conversion by a new type of fuel element available is necessary. Two fuel elements in plate type are suggested in this study to be used in the ET-RR-1 reactor core rather than the utilized ones. The first element has a dimension of 8 x 8 x 50 cm and consists of 19.7% enriched uranium, which is typical for that utilized in the ET-RR-2 reactor, but with a different length. The other element is proposed with a dimension of 7 x 7 x 50 cm and has the same uranium enrichment. To accomplish safety requirements for these fuel elements, thermal-hydraulic evaluation has been carried out using the PARET code. To reach a core conversion of the ET-RR-1 reactor with the above two types of fuel elements, neutronic calculations have been performed using WIMSD4, DIXY2 and EREBUS codes. Some important nuclear parameters needed in the physical design of the reactor were calculated and included in this study. (orig.) [German] Der ET-RR-1 Forschungsreaktor wird seit 1961 unter Verwendung von EK-10 Brennelementen mit einer Leistung von 2 MW betrieben. Der Reaktor wird in der angewandten Forschung und zur Isotopenherstellung eingesetzt. Um die Reaktorleistung im Hinblick auf eine zeitgemaesse Nutzung der Anlage in einem vernuenftigen Mass zu erhoehen, ist eine Umwandlung des Kerns durch Verwendung neuartiger Brennelemente noetig. In der vorliegenden Untersuchung wird vorgeschlagen, anstelle der z. Z. verwendeten Elemente zwei neue, plattenfoermige Brennelemente zu verwenden. Das erste Element hat eine Groesse von 8 x 8 x 50 cm und besteht aus 19,7% angereichertem Uran, was den im ET-RR-2 Reaktor verwendeten Elementen entspricht, allerdings mit einer anderen Groesse. Das zweite Element hat die gleiche
Energy Technology Data Exchange (ETDEWEB)
Frade, Rangel Teixeira
2015-07-01
Plate type fuel elements are used in MTR research nuclear reactors. The fuel plates are manufactured by assembling a briquette containing the fissile material inserted in a frame, with metal plates in both sides of the set, to act as a cladding. This set is rolled under controlled conditions in order to obtain the fuel plate. In Brazil, this type of fuel is manufactured by IPEN and used in the IEA-R1 reactor. After fabrication of three batches of fuel plates, 24 plates, one of them is taken, in order to verify the thickness of the cladding. For this purpose, the plate is sectioned and the thickness measurements are carried out by using optical microscopy. This procedure implies in damage of the plate, with the consequent cost. Besides, the process of sample preparation for optical microscopy analysis is time consuming, it is necessary an infrastructure for handling radioactive materials and there is a generation of radioactive residues during the process. The objective of this study was verify the applicability of eddy current test method for nondestructive measurement of cladding thickness in plate type nuclear fuels, enabling the inspection of all manufactured fuel plates. For this purpose, reference standards, representative of the cladding of the fuel plates, were manufactured using thermomechanical processing conditions similar to those used for plates manufacturing. Due to no availability of fuel plates for performing the experiments, the presence of the plate’s core was simulated using materials with different electrical conductivities, fixed to the thickness reference standards. Probes of eddy current testing were designed and manufactured. They showed high sensitivity to thickness variations, being able to separate small thickness changes. The sensitivity was higher in tests performed on the reference standards and samples without the presence of the materials simulating the core. For examination of the cladding with influence of materials simulating the
A SET OF 12-PARAMETER RECTANGULAR PLATE ELEMENT WITH HIGH ACCURACY
Institute of Scientific and Technical Information of China (English)
ChenShaochun; LuoLaixing
1999-01-01
Abstract. Using the method of undetermined function, a set of 12 parameter rectangular p|atedement with doub[e set parameter and geometry symmetry is constructed. Their consistencyerror are O(h2) , one order higher than the usua[ 12 parameter rectangu|ar p[ate elements.
Simulations of Propagation and Radiation of A0-mode Lamb Wave in Ultrasonic Waveguide Sensor
Energy Technology Data Exchange (ETDEWEB)
Bae, Jin Ho; Joo, Young Sang; Kim, Jong Bum [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Rhee, Hui Nam [Sunchon National University, Sunchon (Korea, Republic of)
2010-10-15
As the sodium coolant of a sodium-cooled fast reactor (SFR) is opaque to light, a conventional visual inspection cannot be used for carrying out an in-service inspection of the internal structures under a sodium level. An ultrasonic wave should be applied for an under-sodium viewing of the internal structures in a reactor vessel. Recently, a new plate type ultrasonic waveguide sensor has been developed for the versatile applications in the under-sodium viewing application. In the plate type ultrasonic waveguide sensor, the A0 mode Lamb wave is utilized for the long distance propagation and the effective radiation capability in a fluid. And a radiation beam steering technique is presented which is capable of steering an ultrasonic radiation beam of a waveguide sensor without a mechanical movement of the sensor module. In this paper, the numerical simulation of the propagation and radiation of A0-mode Lamb wave in ultrasonic leaky wave generation from waveguide sensor is performed by using the finite element method (FEM). The objective of this research is to compare the previous theoretical and experimental results with its numerical simulation
A Broadband Terahertz Waveguide T-Junction Variable Power Splitter.
Reichel, Kimberly S; Mendis, Rajind; Mittleman, Daniel M
2016-06-29
In order for the promise of terahertz (THz) wireless communications to become a reality, many new devices need to be developed, such as those for routing THz waves. We demonstrate a power splitting router based on a parallel-plate waveguide (PPWG) T-junction excited by the TE1 waveguide mode. By integrating a small triangular septum into the waveguide plate, we are able to direct the THz light down either one of the two output channels with precise control over the ratio between waveguide outputs. We find good agreement between experiment and simulation in both amplitude and phase. We show that the ratio between waveguide outputs varies exponentially with septum translation offset and that nearly 100% transmission can be achieved. The splitter operates over almost the entire range in which the waveguide is single mode, providing a sensitive and broadband method for THz power splitting.
A Broadband Terahertz Waveguide T-Junction Variable Power Splitter
Reichel, Kimberly S.; Mendis, Rajind; Mittleman, Daniel M.
2016-06-01
In order for the promise of terahertz (THz) wireless communications to become a reality, many new devices need to be developed, such as those for routing THz waves. We demonstrate a power splitting router based on a parallel-plate waveguide (PPWG) T-junction excited by the TE1 waveguide mode. By integrating a small triangular septum into the waveguide plate, we are able to direct the THz light down either one of the two output channels with precise control over the ratio between waveguide outputs. We find good agreement between experiment and simulation in both amplitude and phase. We show that the ratio between waveguide outputs varies exponentially with septum translation offset and that nearly 100% transmission can be achieved. The splitter operates over almost the entire range in which the waveguide is single mode, providing a sensitive and broadband method for THz power splitting.
Directory of Open Access Journals (Sweden)
Elyas Ghafoori
2014-04-01
Full Text Available Many old riveted steel bridges remain operational and require retrofit to accommodate ever increasing demands. Complicating retrofit efforts, riveted steel bridges are often considered historical structures where structural modifications that affect the original construction are to be avoided. The presence of rivets along with preservation requirements often prevent the use of traditional retrofit methods, such as bonding of fiber reinforced composites, or the addition of supplementary steel elements. In this paper, an un-bonded post-tensioning retrofit method is numerically investigated using existing railway riveted bridge geometry in Switzerland. The finite element (FE model consists of a global dynamic model for the whole bridge and a more refined sub-model for a riveted joint. The FE model results include dynamic effects from axle loads and are compared with field measurements. Pre-stressed un-bonded carbon fiber reinforced plastic (CFRP plates will be considered for the strengthening elements. Fatigue critical regions of the bridge are identified, and the effects of the un-bonded post-tensioning method with different pre-stress levels on fatigue susceptibility are explored. With an applied 40% CFRP pre-stress, fatigue damage reductions of more than 87% and 85% are achieved at the longitudinal-to-cross beam connections and cross-beam bottom flanges, respectively.
Finite Element Analysis for Effect of Roll Radius on Metal Deformation of Hot Rolling Plate
Institute of Scientific and Technical Information of China (English)
LUO De-xing; CHEN Qi-an; LIU Li-wen
2005-01-01
The deformation of rolling piece in hot rolling by flat roll with different radii is analyzed with three-dimensional large deformation thermo-mechanical coupling finite element method. The distribution laws of stress, strain and strain energy density in deformation zone with rolls of different radii were studied. The result indicated that under the same condition, the larger the roll radius is, the more vigorous the deformation in deformation zone is.
1983-05-01
Ship Research and Program emen Development Center Task Area ZR0140201 Bethesda, Maryland 20084 Work Unit 1844-140 II . CONTROLLING OFFICE NAME AND ADDRESS...solution has singular behavior, then only the norm II .112 can be used. This approach has the following several advantages and disadvantages: 1) Advantages...34 Bollettino Unione Matematica Italiana, Bologna, Vol. 10, pp. 133-140 (1974). 14. Ciarlet, P. and P. aviart, "A Mixed Finite Element Method for the Biharmonic
Directory of Open Access Journals (Sweden)
Li Ming Zhou
2016-01-01
Full Text Available Based on the finite element software ABAQUS and graded element method, we developed a dummy node fracture element, wrote the user subroutines UMAT and UEL, and solved the energy release rate component of functionally graded material (FGM plates with cracks. An interface element tailored for the virtual crack closure technique (VCCT was applied. Fixed cracks and moving cracks under dynamic loads were simulated. The results were compared to other VCCT-based analyses. With the implementation of a crack speed function within the element, it can be easily expanded to the cases of varying crack velocities, without convergence difficulty for all cases. Neither singular element nor collapsed element was required. Therefore, due to its simplicity, the VCCT interface element is a potential tool for engineers to conduct dynamic fracture analysis in conjunction with commercial finite element analysis codes.
Energy Technology Data Exchange (ETDEWEB)
Ronzhin, A. [Fermilab; Los, S. [Fermilab; Ramberg, E. [Fermilab; Spiropulu, M. [Caltech; Apresyan, A. [Caltech; Xie, S. [Caltech; Kim, H. [Chicago U.; Zatserklyaniy, A. [UC, Santa Cruz
2014-09-21
One possibility to make a fast and radiation resistant shower maximum (SM) detector is to use a secondary emitter as an active element. We present below test beam results, obtained with different types of photodetectors based on microchannel plates (MCPs) as the secondary emitter. We performed the measurements at the Fermilab Test Beam Facility with 120GeV proton beam and 12GeV and 32GeV secondary beams. The goal of the measurement with 120GeV protons was to determine time resolution for minimum ionizing particles (MIPs). The SM time resolution we obtained for this new type of detector is at the level of 20-30ps. We estimate that a significant contribution to the detector response originates from secondary emission of the MCP. This work can be considered as the first step in building a new type of calorimeter based on this principle.
Energy Technology Data Exchange (ETDEWEB)
Ronzhin, A. [Fermilab; Los, S. [Fermilab; Ramberg, E. [Fermilab; Spiropulu, M. [Caltech; Apresyan, A. [Caltech; Xie, S. [Caltech; Kim, H. [Chicago U.; Zatserklyaniy, A. [UC, Santa Cruz
2014-09-21
One possibility to make a fast and radiation resistant shower maximum (SM) detector is to use a secondary emitter as an active element. We present below test beam results, obtained with different types of photodetectors based on microchannel plates (MCPs) as the secondary emitter. We performed the measurements at the Fermilab Test Beam Facility with 120GeV proton beam and 12GeV and 32GeV secondary beams. The goal of the measurement with 120GeV protons was to determine time resolution for minimum ionizing particles (MIPs). The SM time resolution we obtained for this new type of detector is at the level of 20-30ps. We estimate that a significant contribution to the detector response originates from secondary emission of the MCP. This work can be considered as the first step in building a new type of calorimeter based on this principle.
Directory of Open Access Journals (Sweden)
Guo Ruijiang
1995-01-01
Full Text Available A finite element based sensitivity analysis procedure is developed for buckling and postbuckling of composite plates. This procedure is based on the direct differentiation approach combined with the reference volume concept. Linear elastic material model and nonlinear geometric relations are used. The sensitivity analysis technique results in a set of linear algebraic equations which are easy to solve. The procedure developed provides the sensitivity derivatives directly from the current load and responses by solving the set of linear equations. Numerical results are presented and are compared with those obtained using finite difference technique. The results show good agreement except at points near critical buckling load where discontinuities occur. The procedure is very efficient computationally.
Research on the interfacial behaviors of plate-type dispersion nuclear fuel elements
Wang, Qiming; Yan, Xiaoqing; Ding, Shurong; Huo, Yongzhong
2010-04-01
The three-dimensional constitutive relations are constructed, respectively, for the fuel particles, the metal matrix and the cladding of dispersion nuclear fuel elements, allowing for the effects of large deformation and thermal-elastoplasticity. According to the constitutive relations, the method of modeling their irradiation behaviors in ABAQUS is developed and validated. Numerical simulations of the interfacial performances between the fuel meat and the cladding are implemented with the developed finite element models for different micro-structures of the fuel meat. The research results indicate that: (1) the interfacial tensile stresses and shear stresses for some cases will increase with burnup, but the relative stresses will decrease with burnup for some micro-structures; (2) at the lower burnups, the interfacial stresses increase with the particle sizes and the particle volume fractions; however, it is not the case at the higher burnups; (3) the particle distribution characteristics distinctly affect the interfacial stresses, and the face-centered cubic case has the best interfacial performance of the three considered cases.
Washburn, Adam L; Bailey, Ryan C
2011-01-21
By leveraging advances in semiconductor microfabrication technologies, chip-integrated optical biosensors are poised to make an impact as scalable and multiplexable bioanalytical measurement tools for lab-on-a-chip applications. In particular, waveguide-based optical sensing technology appears to be exceptionally amenable to chip integration and miniaturization, and, as a result, the recent literature is replete with examples of chip-integrated waveguide sensing platforms developed to address a wide range of contemporary analytical challenges. As an overview of the most recent advances within this dynamic field, this review highlights work from the last 2-3 years in the areas of grating-coupled, interferometric, photonic crystal, and microresonator waveguide sensors. With a focus towards device integration, particular emphasis is placed on demonstrations of biosensing using these technologies within microfluidically controlled environments. In addition, examples of multiplexed detection and sensing within complex matrices--important features for real-world applicability--are given special attention.
Mashima, H.
2003-12-01
Based on geochemistry, the recent favor model for within-plate basalts (WPB) is plumes with eclogite originally formed by inversion of basaltic oceanic crust into eclogite in subduction zones (e.g. Hauri, 1996). Melting experiments of basalt/peridotie hybrids (Kogiso and Takahashi, 1998), however, have demonstrated that the hybrid source model could not explain major element features of WPB, such as FeO* enrichment and Al2O3 depletion compared with MORB. Melting experiments of peridotites and basalt/peridotite hybrids indicate that the sources of WPB are peridotites abnormally enriched in FeO*. Such Fe-rich sources could not be formed by extraction of basalt melt from typical peridotite or mixing of basalt and typical peridotite. A potential candidate for the abnormally Fe-rich source is Archean peridotitic komatiite (APK) which is enriched in FeO* compared with typical peridotite. Attractive features of the recycled APK melting model are as follows: 1) It explains why within-plate basalts are FeO*-rich and Al2O3-poor relative to MORB because of large proportion of cpx in APK. 2) Moderate partial melting of APK forms LREE-enriched partial melts because of selective fusion of cpx. 3) It explains near bulk earth Nd isotope compositions because of relatively flat REE patterns of APK. 4) Archean age of APK is consistent with Pb isotope ofWPB suggesting their sources have Archean age. 5) Compositional spectrum of Archean komatiite suites ranging from peridotitic komatiite to basalts explains that of WPB from silica-under saturated basalt to silica-oversaturated andesite.
A Waveguide Transverse Broad Wall Slot Radiating Between Baffles
DEFF Research Database (Denmark)
Dich, Mikael; Rengarajan, S.R.
1997-01-01
An analysis of the self impedance of waveguide-fed transverse slots radiating between baffles is presented. The region exterior to the slot is treated as a parallel plate (PP) waveguide which radiates into half space through an aperture in an infinite ground plane. The slot problem is analyzed...
Polymers in Waveguide Packaging
Institute of Scientific and Technical Information of China (English)
Zhiyi Zhang; G. Z.Xiao; Jiaren Liu; C. P. Grover
2003-01-01
Polymers were successfully used in the packaging of waveguide-based photonic components in the area of fiber-to-waveguide coupling, waveguide die attachment, strain relief, and waveguide encapsulation. The application results of these polymers were described in this paper.
Energy Technology Data Exchange (ETDEWEB)
Lee, Jungki; Kim, Ji Hyun [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)
2015-10-15
With same roll speed and same friction coefficient, curvature is formed on rolled product from FEA result. To reduce this curvature and plastic strain which cause reduction in fabricability, two ways are selected; (i) controlling upper/lower roll speed, and (ii) adjusting upper/lower friction coefficient and contacts. Both results shows it can reduce the curvature and equivalent plastic strain of the plate after the rolling. It can be applied in real plate rolling processing and also the next research for pilgering process for tube and pipe production. The FEA results of equivalent stress and plastic deformation distribution are showed in figure 5. The von-Mises equivalent stress distribution showed that the stress is still concentrated on upper Fe-12Cr-2Si layer, however, it also shows that equivalent plastic strain is distributed uniformly comparing with upper and lower roll speed ratio is 1.0. In high temperature liquid metal environment, there are usually two types of corrosion; one is corrosion by dissolution of alloy elements into liquid metal, and another is corrosion by chemical reaction among impurities in liquid metal and structural alloy. There have been some researches to develop new alloys that can form more dense scale on the surface even in wider impurity range and higher temperature range . M.P Short et al. devised functionally graded composite which is composed of two layers . one is a thin corrosion resistant layer and another is thick structural layer which guarantees mechanical strength, creep rupture strength and shows less irradiation swelling.
A remark on the computation of shear-horizontal and torsional modes in elastic waveguides.
Gravenkamp, Hauke
2016-07-01
When modeling the propagation of elastic guided waves in plates or cylinders, Finite Element based numerical methods such as the Scaled Boundary Finite Element Method (SBFEM) or the Semi-Analytical Finite Element (SAFE) Method lead to an eigenvalue problem to be solved at each frequency. For the particular case of shear horizontal modes in a homogeneous plate or torsional modes in a homogeneous cylinder, the problem can be drastically simplified. The eigenvalues become simple functions of the frequency, while the eigenvectors are constant. The current contribution discusses how this behavior is represented in the numerical formulation and derives the expressions for the eigenvalues and eigenvectors as well as the dynamic stiffness matrix of infinite elastic waveguides.
Analysis of Radiation Beam of a Leaky Lamb Wave in Ultrasonic Waveguide Sensor
Energy Technology Data Exchange (ETDEWEB)
Joo, Y. S.; Bae, J. H.; Park, C. G.; Lee, J. H.
2010-02-15
The theoretical and experimental study of the propagation and radiation of leaky Lamb wave in a plate waveguide sensor has been carried out. In the plate waveguide sensor, the A{sub 0} leaky Lamb wave is utilized for the single mode generation and the effective radiation capability in a fluid. The plate waveguide sensor which consists of a plate waveguide, a teflon wedge and an ultrasonic sensor has been designed and manufactured. The tone-burst excitation of high power long pulse should be applied to minimize the dispersion effect in 10 m long distance propagation of the A{sub 0} Lamb wave. A novel technique which is capable of steering a radiation beam of a waveguide sensor without a mechanical movement can be achieved by a frequency tuning method of the excitation pulse in the dispersive low frequency range of the A{sub 0} Lamb wave. The characteristics of radiation beam of ultrasonic waveguide sensors has been investigated by the beam profile measurements according to the plate thickness, the radiation aperture length, the pulse cycles and the excitation frequency. The design parameters of the plate waveguide sensor has been optimized. The C-scanning experiments in water have been carried out for the performance of the optimized ultrasonic waveguide sensor. The poulsbility of C-scan visualization using the plate waveguide sensor has been verified
Ma, Ching-Hou; Wu, Chin-Hsien; Tu, Yuan-Kun; Lin, Ting-Sheng
2013-08-01
We evaluated both the outcome of using a locking plate as a definitive external fixator for treating open tibial fractures and, using finite element analysis, the biomechanical performance of external and internal metaphyseal locked plates in treating proximal tibial fractures. Eight open tibial patients were treated using a metaphyseal locked plate as a low-profile definitive external fixator. Then, finite element models of internal (IPF) as well as two different external plate fixations (EPFs) for proximal tibial fractures were reconstructed. The offset distances from the bone surface to the EPFs were 6 cm and 10 cm. Both axial stiffness and angular stiffness were calculated to evaluate the biomechanical performance of these three models. The mean follow-up period was 31 months (range, 18-43 months). All the fractures united and the mean bone healing time was 37.5 weeks (range, 20-52 weeks). All patients had excellent or good functional results and were walking freely at the final follow-up. The finite element finding revealed that axial stiffness and angular stiffness decreased as the offset distance from the bone surface increased. Compared to the IPF models, in the two EPF models, axial stiffness decreased by 84-94%, whereas the angular stiffness decreased by 12-21%. The locking plate used as a definitive external fixator provided a high rate of union. While the locking plate is not totally rigid, it is clinically stable and may be advisable for stiffness reduction of plating constructs, thus promoting fracture healing by callus formation. Our patients experienced a comfortable clinical course, excellent knee and ankle joint motion, satisfactory functional results and an acceptable complication rate.
Energy Technology Data Exchange (ETDEWEB)
Flamm, H.; Lochau, R.; Maeiss, M.; Schiele, J.
1984-07-01
In a newly constructed south-west-facade 200 m/sup 2/ of flat plate collectors were integrated as construction elements to heat domestic water. The building needs 5-10 m/sup 3/ of hot water per day, i.e. 250-500 kWh/d. The solar circuit runs with a water-glycol-mixture with a specific volume flow rate of 20-40 l/m/sup 2/h. The storage capacity is 8 m/sup 3/, i.e. 40 l/m/sup 2/ collector area. The heating system is bivalent. The total cost was DM 220.000, excepting the cost of facade construction. The observation period was 2 years. The heat flow balance was measured daily using a microprocessor. As far as the construction was concerned, there were no defects during the observation period. The rooms behind solar collectors showed no additional thermal load. The most favourable season for running solar systems is from April to September. In this period the average efficiencies were 15 to 20%, the net energy yield was 76 kWh/m/sup 2/.
Exner, Pavel
2015-01-01
This monograph explains the theory of quantum waveguides, that is, dynamics of quantum particles confined to regions in the form of tubes, layers, networks, etc. The focus is on relations between the confinement geometry on the one hand and the spectral and scattering properties of the corresponding quantum Hamiltonians on the other. Perturbations of such operators, in particular, by external fields are also considered. The volume provides a unique summary of twenty five years of research activity in this area and indicates ways in which the theory can develop further. The book is fairly self-contained. While it requires some broader mathematical physics background, all the basic concepts are properly explained and proofs of most theorems are given in detail, so there is no need for additional sources. Without a parallel in the literature, the monograph by Exner and Kovarik guides the reader through this new and exciting field.
Plasmonic antennas hybridized with dielectric waveguides.
Bernal Arango, Felipe; Kwadrin, Andrej; Koenderink, A Femius
2012-11-27
For the purpose of using plasmonics in an integrated scheme where single emitters can be probed efficiently, we experimentally and theoretically study the scattering properties of single nanorod gold antennas as well as antenna arrays placed on one-dimensional dielectric silicon nitride waveguides. Using real space and Fourier microscopy correlated with waveguide transmission measurements, we quantify the spectral properties, absolute strength, and directivity of scattering. The scattering processes can be well understood in the framework of the physics of dipolar objects placed on a planar layered environment with a waveguiding layer. We use the single plasmonic structures on top of the waveguide as dipolar building blocks for new types of antennas where the waveguide enhances the coupling between antenna elements. We report on waveguide hybridized Yagi-Uda antennas which show directionality in out-coupling of guided modes as well as directionality for in-coupling into the waveguide of localized excitations positioned at the feed element. These measurements together with simulations demonstrate that this system is ideal as a platform for plasmon quantum optics schemes as well as for fluorescence lab-on-chip applications.
Compact waveguide circular polarizer
Tantawi, Sami G.
2016-08-16
A multi-port waveguide is provided having a rectangular waveguide that includes a Y-shape structure with first top arm having a first rectangular waveguide port, a second top arm with second rectangular waveguide port, and a base arm with a third rectangular waveguide port for supporting a TE.sub.10 mode and a TE.sub.20 mode, where the end of the third rectangular waveguide port includes rounded edges that are parallel to a z-axis of the waveguide, a circular waveguide having a circular waveguide port for supporting a left hand and a right hand circular polarization TE.sub.11 mode and is coupled to a base arm broad wall, and a matching feature disposed on the base arm broad wall opposite of the circular waveguide for terminating the third rectangular waveguide port, where the first rectangular waveguide port, the second rectangular waveguide port and the circular waveguide port are capable of supporting 4-modes of operation.
Institute of Scientific and Technical Information of China (English)
PANI P. K.; BHATTACHARYYA S. K.
2009-01-01
The dynamic pressure distribution on a rectangular plate attached to a rigid wall and supporting an infinitely large extent of fluid subjected to a harmonic ground excitation is evaluated in the time domain. Governing equations for the fluid domain are set considering the compressibility of the fluid with negligibly small change in density and a linearized free surface. A far boundary condition for the three-dimensional fluid domain is developed so that the far boundary is truncated at a closer proximity to the structure. The coupled problem is solved independently for the structure and the fluid domain by transferring the acceleration of the plate to the fluid and pressure of the fluid to the plate in sequence. Helmholtz equation for the three-dimensional fluid domain and Mindlin's theory for the two-dimensional plate are used for the solution of the interacting domains. Finite element technique is adopted for the solution of this problem with pressure as nodal variable for the fluid domain and displacement for the plate. The time dependent equations are solved in each of the interacting domain using Newmark-b method. The effectiveness of the technique is demonstrated and the influences of surface wave, exciting frequency and flexibility of the plate on dynamic pressure are investigated.
Institute of Scientific and Technical Information of China (English)
LI Xiaohe; LI Zhijun; GAO Shang
2015-01-01
Objective:To analysis through the mouth atlanto-axial vertebral anterior plate fixation in finite element for the development of the segmental anterior fixation surgery and to provide the reference of inner plant im-provement. Methods:One case, male, 36 years old, 64 kg weight was randomly selected from January 2014 to our hospital to check no-skull - atlanto-axial vertebral disease . It was scanned by 0. 625 mm thin layer, Image data were rebuilted in the Mimics 16. 01 software, Pro/ENGINEER 4. 0 software was used to rebuilt atlanto-axial vertebral anterior plate, After reconstruction of steel screw 3 d model according to the classic through the mouth , the model was imported into Mimics 16. 01 and the model surface was meshed and material was assigned, The mod-el was forced 80 N vertical loading, the surface was applied 15 nm torque, to simulat three motion state example, forward bends, stretch, side-bending, The stress and deformation of screw and rod were measured. Results: At-lanto-axial vertebral three-dimensional reconstruction model were divided into 14 514 individual grid, 7 257 nodes, the model was loaded, The stress of upper screw root in bend was biggest (62. 34 ±5. 52) Mpa (F=73. 23, P<0. 05, the difference was statistically significant). A screw of the root and the top, lateral stress was the largest, respectively were (78. 42 ± 5. 5. 14) Mpa (F=112. 32, P<0. 05);(95. 48 ± 7. 12 Mpa (F=62. 32, P<0. 05), the difference was statistical significance; Under three different motion state and a screw root stress, Upper screw root stress in bending forward was greater than the lower (forward bends, stretch and lateral bending state , t value were 12. 2, 9. 23, 22. 98, P<0. 05, differences were statistically significant), and in the lateral current screw root stress was greater than the upper; In the same movement state, the top was greater than the root, the differences were statistically significant (forward bends, stretch and lateral bending state after
Huang, Shao-Fu; Lo, Lun-Jou; Lin, Chun-Li
2016-12-01
This study investigates the biomechanical interaction of different mini-plate fixation types (shapes/sizes and patterns) with segmental advancement levels on the Le Fort I osteotomy using the non-linear finite element (FE) approach. Nine models were generated under a standard 1-piece LeFort I osteotomy for advancement with 3, 6 and 9 mm distances and four mini-plates with three fixation patterns including LL, LI, and II patterns placed on the maxillae models by integrating computed tomography images and computer-aided design system. The axial and oblique occlusal forces were 250 N applied to each premolar/molar and 125 N applied at 30° inclination to the tooth long axis and from palatal to buccal, respectively. The relative micro-movement values between the two maxillary bone segments and maximum mini-plate stress increased obviously with maxilla advancement increment and the increasing trend can be fitted by exponential curve. The corresponding values in II mini-plate fixation presented apparently high values in all simulated cases. The mini-plate stress concentration locations were found at the bending regions to increase high fracture risk. The mini-plate yield strength can be mapped to a critical (limited) advancement for three types of fixations for safe consideration. This study concluded that L-shaped mini-plates with lateral fixation are recommended to provide better stability. The risk for mini-plate fracture and bone relapse increases when maxillary advancement is larger than a critical value of 5 mm in the Le Fort I osteotomy.
关于高精度12参矩形板元的分析%Analysis on a Set of 12-parameter Rectangular Plate Element with High Accuracy
Institute of Scientific and Technical Information of China (English)
石东洋; 王彩霞
2006-01-01
It is proved that the so-called a set of 12-parameter rectangular plate elements with high accuracy constructed by using double set parameter method and undetermined method are, in fact, the same one; the real shape function space is nothing but the Adini's element's, which has nothing to do with the other high degree terms and leads to a new method for constructing the high accuracy plate elements. This fact has never been seen for other conventional and unconventional, conforming and nonconforming rectangular plate elements, such as Quasi-conforming elements, generalized conforming elements and other double set parameter finite elements. Moreover, such kind of rectangular elements can not be constructed by the conventional finite element methods.
Chen, B. C. J.; Hartop, R. W.
1981-04-01
An improved system is described for cooling high power waveguides by the use of cooling ducts extending along the waveguide, which minimizes hot spots at the flanges where waveguide sections are connected together. The cooling duct extends along substantially the full length of the waveguide section, and each flange at the end of the section has a through hole with an inner end connected to the duct and an opposite end that can be aligned with a flange hole in another waveguide section. Earth flange is formed with a drainage groove in its face, between the through hole and the waveguide conduit to prevent leakage of cooling fluid into the waveguide. The ducts have narrowed sections immediately adjacent to the flanges to provide room for the installation of fasteners closely around the waveguide channel.
Microfabricated Waveguide Atom Traps.
Energy Technology Data Exchange (ETDEWEB)
Jau, Yuan-Yu
2017-09-01
A nano - scale , microfabricated waveguide structure can in - principle be used to trap atoms in well - defined locations and enable strong photon - atom interactions . A neutral - atom platf orm based on this microfabrication technology will be pre - aligned , which is especially important for quantum - control applications. At present, there is still no reported demonstration of evanescent - field atom trapping using a microfabricated waveguide structure. We described the capabilities established by our team for future development of the waveguide atom - trapping technology at SNL and report our studies to overcome the technical challenges of loading cold atoms into the waveguide atom traps, efficient and broadband optical coupling to a waveguide, and the waveguide material for high - power optical transmission. From the atomic - physics and the waveguide modeling, w e have shown that a square nano - waveguide can be utilized t o achieve better atomic spin squeezing than using a nanofiber for first time.
Van Long, Nguyen; Quoc, Tran Huu; Tu, Tran Minh
2016-12-01
In this paper, a new eight-unknown shear deformation theory is developed for bending and free vibration analysis of functionally graded plates by finite-element method. The theory based on full 12-unknown higher order shear deformation theory simultaneously satisfies zeros transverse stresses at top and bottom surfaces of FG plates. A four-node rectangular element with 16 degrees of freedom per node is used. Poisson's ratios, Young's moduli, and material densities vary continuously in thickness direction according to the volume fraction of constituents which is modeled as power-law functions. Results are verified with available results in the literature. Parametric studies are performed for different power-law indices, side-to-thickness ratios.
PLANAR OPTICAL WAVEGUIDES WITH PHOTONIC CRYSTAL STRUCTURE
DEFF Research Database (Denmark)
2003-01-01
Planar optical waveguide comprising a core region and a cladding region comprising a photonic crystal material, said photonic crystal material having a lattice of column elements, wherein at least a number of said column elements are elongated substantially in an axial direction for said core reg...
Fabrication slab waveguide based polymethyl methacrylate (PMMA) with spin coating method
Andriawan, Alan; Pramono, Yono Hadi; Masoed, Asnawi
2016-11-01
Fabrication and characterization slab waveguide based polymethyl methacrylate (PMMA) has been carried out. Slab waveguide fabrication done by the spin coating method. Slab waveguide fabrication process carried out by the rotational speed of 1000, 2000, and 3000 rpm respectively played for 10 seconds. Then the slab waveguides heated using a hot plate. Heating process starting from room temperature then increased 5°C to 70°C with a 5 minute warm-up time interval. From the results of characterization fabricated slab waveguides to determine the film thickness is made. Then made observations on the waveguide by passing the light beam He-Ne laser on the thin layer through a single mode optical fiber. From the results of characterization is known that the fabrication of a slab waveguide with a layer thickness of 166 μm. From this research it is known that polymethyl methacrylate (PMMA) can be used as a waveguide with a spin coating method.
Directory of Open Access Journals (Sweden)
Ugo Icardi
2015-01-01
Full Text Available A C° layerwise plate element with standard nodal d.o.f. and serendipity interpolation functions is applied to the analysis of laminates and sandwiches giving rise to strong layerwise effects. The element is obtained using an energy updating technique and symbolic calculus starting from a physically-based zig-zag model with variable kinematics and fixed d.o.f. able to a priori satisfy to displacement and stress continuity at the material interfaces. Non classical feature, a high-order piecewise zig-zag variation of the transverse displacement is assumed as it helps keeping equilibrium. Crushing of core is studied carrying apart a detailed 3D modelling of the honeycomb structure discretizing the cell walls with plate elements, with the aim of obtaining apparent elastic moduli at each load level. Using such apparent moduli, a 2D homogenized analysis is carried out simulating sandwiches as multi-layered structures Applications are presented to plates undergoing impulsive loading incorporating plies with spatially variable stiffness properties. It is shown that accurate predictions are always obtained in in the numerical applications with a very low computational effort. Compared to kinematically based zig-zag models, present physically based one is proven to more accurate, being always in a good agreement with exact 3D solutions.
Excitation of waves in elastic waveguides by piezoelectric patch actuators
CSIR Research Space (South Africa)
Loveday, PW
2006-01-01
Full Text Available to be an infinite waveguide. The excitation of waves in waveguides may be analysed in the time domain using conventional finite element methods. This analysis is computationally very demanding as the model must be a number of wavelengths long to avoid the influence...
Reconfigurable origami-inspired acoustic waveguides
Babaee, Sahab; Overvelde, Johannes T. B.; Chen, Elizabeth R.; Tournat, Vincent; Bertoldi, Katia
2016-01-01
We combine numerical simulations and experiments to design a new class of reconfigurable waveguides based on three-dimensional origami-inspired metamaterials. Our strategy builds on the fact that the rigid plates and hinges forming these structures define networks of tubes that can be easily reconfigured. As such, they provide an ideal platform to actively control and redirect the propagation of sound. We design reconfigurable systems that, depending on the externally applied deformation, can act as networks of waveguides oriented along one, two, or three preferential directions. Moreover, we demonstrate that the capability of the structure to guide and radiate acoustic energy along predefined directions can be easily switched on and off, as the networks of tubes are reversibly formed and disrupted. The proposed designs expand the ability of existing acoustic metamaterials and exploit complex waveguiding to enhance control over propagation and radiation of acoustic energy, opening avenues for the design of a new class of tunable acoustic functional systems. PMID:28138527
Reconfigurable origami-inspired acoustic waveguides.
Babaee, Sahab; Overvelde, Johannes T B; Chen, Elizabeth R; Tournat, Vincent; Bertoldi, Katia
2016-11-01
We combine numerical simulations and experiments to design a new class of reconfigurable waveguides based on three-dimensional origami-inspired metamaterials. Our strategy builds on the fact that the rigid plates and hinges forming these structures define networks of tubes that can be easily reconfigured. As such, they provide an ideal platform to actively control and redirect the propagation of sound. We design reconfigurable systems that, depending on the externally applied deformation, can act as networks of waveguides oriented along one, two, or three preferential directions. Moreover, we demonstrate that the capability of the structure to guide and radiate acoustic energy along predefined directions can be easily switched on and off, as the networks of tubes are reversibly formed and disrupted. The proposed designs expand the ability of existing acoustic metamaterials and exploit complex waveguiding to enhance control over propagation and radiation of acoustic energy, opening avenues for the design of a new class of tunable acoustic functional systems.
Energy Technology Data Exchange (ETDEWEB)
Brower, Jeffrey Owen [Idaho National Lab. (INL), Idaho Falls, ID (United States); Glazoff, Michael Vasily [Idaho National Lab. (INL), Idaho Falls, ID (United States); Eiden, Thomas John [Idaho National Lab. (INL), Idaho Falls, ID (United States); Rezvoi, Aleksey Victor [Idaho National Lab. (INL), Idaho Falls, ID (United States)
2016-08-01
Advanced Test Reactor (ATR) Cycle 153B-1 was a 14-day, high-power, powered axial locator mechanism (PALM) operating cycle that completed on April 12, 2013. Cycle 153B-1 was a typical operating cycle for the ATR and did not result in any unusual plant transients. ATR was started up and shut down as scheduled. The PALM drive physically moves the selected experiments into and out of the core to simulate reactor startup and heat up, and shutdown and cooldown transients, while the reactor remains in steady state conditions. However, after the cycle was over, several thousand of the flow-assisted corrosion pits and “horseshoeing” defects were readily observable on the surface of the several YA-type fuel elements (these are “dummy” plates that contain no fuel). In order understand these corrosion phenomena a thermal-hydraulic model of coolant channel 20 on a YA-M fuel element was generated. The boundaries of the model were the aluminum EE plate of a YA-M fuel element and a beryllium reflector block with 13 horizontal saw cuts which represented regions of zero flow. The heat generated in fuel plates 1 through 18 was modeled to be passing through the aluminum EE plate. The coolant channel 20 width was set at 0.058 in. (58 mils). It was established that the horizontal saw cuts had a significant effect on the temperature of the coolant. The flow, which was expected to vary linearly with gradual heating of the coolant as it passed through the channel, was extremely turbulent. The temperature rise, which was expected to be a smooth “S” curve, was represented by a series temperature rise “humps,” which occurred at each horizontal saw cut in the beryllium reflector block. Each of the 13 saw cuts had a chamfered edge which resulted in the coolant flow being re-directed as a jet across the coolant channel into the surface of the EE plate, which explained the temperature rise and the observed sscalloping and possibly pitting degradation on the YA-M fuel elements. In
Institute of Scientific and Technical Information of China (English)
DING; Li; QIAO; Ya-xin; ZHANG; Nian-peng; LUO; Bei-bei; HUA; Xiao; JIA; Shu-jie; YAN; Hui-yang
2013-01-01
The main aim of this study is to offer the technical support for safety operation and management of research reactors using plate-type fuel assemblies in China,which is performed from analysis of precaution measures for flow blockage and detection methods of accidents.Study shows that most accidents were induced by in-core foreign objects and the swelling of fuel
A Parameter Study of Coupling Properties in Finite Element Models of Single-Stud Double-Plate Panels
DEFF Research Database (Denmark)
Dickow, Kristoffer Ahrens; Domadiya, Parthkumar Gandalal; Andersen, Lars
2011-01-01
Lightweight building techniques are currently progressing fast and using such structures for multi-storey multi-family dwellings is becoming part of the industry standard. Partitions in lightweight buildings are often constructed as plates on frame structures made of either wood or steel. In any ...
Energy Technology Data Exchange (ETDEWEB)
Brower, Jeffrey O. [Idaho National Lab. (INL), Idaho Falls, ID (United States). Advanced Test Reactor; Glazoff, Michael V. [Idaho National Lab. (INL), Idaho Falls, ID (United States). Advanced Test Reactor; Eiden, Thomas J. [Idaho National Lab. (INL), Idaho Falls, ID (United States). Advanced Test Reactor; Rezvoi, Aleksey V. [Idaho National Lab. (INL), Idaho Falls, ID (United States). Advanced Test Reactor
2016-08-01
Advanced Test Reactor (ATR) Cycle 153B-1 was a 14-day, high-power, powered axial locator mechanism (PALM) operating cycle that completed on April 12, 2013. Cycle 153B-1 was a typical operating cycle for the ATR and did not result in any unusual plant transients. ATR was started up and shut down as scheduled. The PALM drive physically moves the selected experiments into and out of the core to simulate reactor startup and heat up, and shutdown and cooldown transients, while the reactor remains in steady state conditions. However, after the cycle was over, when the fuel elements were removed from the core and inspected, several thousand flow-assisted erosion pits and “horseshoeing” defects were readily observed on the surface of the several YA-type fuel elements (these are aluminum “dummy” plates that contain no fuel). In order to understand these erosion phenomena a thermal-hydraulic model of coolant channel 20 on a YA-M fuel element was generated. The boundaries of the model were the aluminum EE plate of a YA-M fuel element and a beryllium reflector block with 13 horizontal saw cuts which represented regions of zero flow. The heat generated in fuel plates 1 through 18 was modeled to be passing through the aluminum EE plate. The coolant channel 20 width was set at 0.058 in. (58 mils). It was established that the horizontal saw cuts had a significant effect on the temperature of the coolant. The flow, which was expected to vary linearly with gradual heating of the coolant as it passed through the channel, was extremely turbulent. The temperature rise, which was expected to be a smooth “S” curve, was represented by a series temperature rise “humps,” which occurred at each horizontal saw cut in the beryllium reflector block. Each of the 13 saw cuts had a chamfered edge which resulted in the coolant flow being re-directed as a jet across the coolant channel into the surface of the EE plate, which explained the temperature rise and the observed scalloping
Graphene antidot lattice waveguides
DEFF Research Database (Denmark)
Pedersen, Jesper Goor; Gunst, Tue; Markussen, Troels
2012-01-01
We introduce graphene antidot lattice waveguides: nanostructured graphene where a region of pristine graphene is sandwiched between regions of graphene antidot lattices. The band gaps in the surrounding antidot lattices enable localized states to emerge in the central waveguide region. We model...... the waveguides via a position-dependent mass term in the Dirac approximation of graphene and arrive at analytical results for the dispersion relation and spinor eigenstates of the localized waveguide modes. To include atomistic details we also use a tight-binding model, which is in excellent agreement...... with the analytical results. The waveguides resemble graphene nanoribbons, but without the particular properties of ribbons that emerge due to the details of the edge. We show that electrons can be guided through kinks without additional resistance and that transport through the waveguides is robust against...
Waveguide characteristics of coupled in-plane waves.
Pan, Jie; Lu, Jing; Qiu, Xiaojun
2012-06-01
In-plane waves in a waveguide made from a thin plate are described by a superposition of a set of orthogonal functions that satisfy the edge conditions of the waveguide. Due to the Poisson and shear effects, the displacement components of the in-plane waves along the two in-plane orthogonal coordinates are coupled and this coupling affects the propagation and spatial properties of the waveguide modes. The orthogonal functions and their associated wavenumbers represent the characteristics of the uncoupled modes of the waveguide where the above mentioned couplings are ignored. This study demonstrates that the characteristics of the waveguide modes are determined by the couplings of the uncoupled mode pairs, which become significant when the pairs satisfy the conditions of spatial coincidence. At some frequencies, certain waveguide modes can be determined by a single pair of uncoupled modes. For this case, the analytical solution for the waveguide modes exists and provides both a qualitative and quantitative interpretation of the characteristics of the waveguide mode.
Directory of Open Access Journals (Sweden)
A Sri Sailam
2014-04-01
Full Text Available The study of unsteady hydro magnetic free convective flow of viscous incompressible and electrically conducting fluids past an infinite vertical porous plate in the presence of constant suction and heat absorbing sinks has been made. Appropriate solutions have been derived for the velocity and temperature fields, skin friction and rate of heat transfer using Galerkin finite element method. It is observed that increase in magnetic field strength decreases the velocity of the fluid. Also the skin friction and rate of heat transfer of the conducting fluid decrease with increase in magnetic field strength.
Light losses from scattering in luminescent solar concentrator waveguides.
Breukers, Robert D; Smith, Gerald J; Stirrat, Hedley L; Swanson, Adam J; Smith, Trevor A; Ghiggino, Kenneth P; Raymond, Sebastiampillai G; Winch, Nicola M; Clarke, David J; Kay, Andrew J
2017-04-01
The reductions in the transmission of emission originating from a fluorophore dissolved in a polymer matrix due to light scattering were compared in two forms of planar waveguides used as luminescent solar concentrators: a thin film of poly(methylmethacrylate) (PMMA) spin-coated on a glass plate and a solid PMMA plate of the same dimensions. The losses attributable to light scattering encountered in the waveguide consisting of the thin film of polymer coated on a glass plate were not detectable within experimental uncertainty, whereas the losses in the solid polymer plate were significant. The losses in the solid plate are interpreted as arising from light-scattering centers comprising minute bubbles of vapor/gas, incomplete polymerization or water clusters that are introduced during or after the thermally induced polymerization process.
MULTIVARIABLE WAVELET FINITE ELEMENT METHOD FOR THIN PLATE ANALYSIS%薄板的多变量小波有限元分析
Institute of Scientific and Technical Information of China (English)
张兴武; 陈雪峰; 王修专; 何正嘉
2011-01-01
Based on B-spline wavelet on the interval (BSWI) and the generalized potential variational principle, a new multivariable wavelet finite element method with two kinds of variables was proposed in the paper. The new corresponding elements for square thin plate, skew thin plate and trapezoidal thin plate were constructed. Firstly, formulations were derived from multivariable generalized potential energy functional. Then the matrix equation of thin plate was obtained by using BSWI as trial function. In this study, the generalized stress and strain were interpolated separately, so differentiation of displacement in traditional method of stress calculation was avoided, and the calculation error was reduced. Besides, the good approximation property of B-spline wavelet on the interval can further guarantee the solving accuracy. Finally, several numerical examples for bending and vibration analysis of square and skew thin plate verified the efficiency and superiority in solving generalized stress.%基于区间B样条小波和广义变分原理,提出了多变量小波有限元法,构造了一种新的薄板多变量小波有限单元.由广义变分原理推导结构的多变量有限元列式,区间B样条小波尺度函数作为插值函数构造的多变量小波有限元法中,广义应力和应变被作为独立变量进行插值,避免了传统方法中应力应变求解的微分运算,减小了计算误差.区间B样条小波良好的数值逼近性能可进一步保证求解精度.通过方形薄板、斜形薄板以及梯形薄板的弯曲和振动分析,验证了此方法的有效性和在广义应力求解中的优越性.
Waveguide arrangements based on adiabatic elimination
Energy Technology Data Exchange (ETDEWEB)
Suchowski, Haim; Mrejen, Michael; Wu, Chihhui; Zhang, Xiang
2016-09-13
This disclosure provides systems, methods, and apparatus related to nanophotonics. In one aspect, an arrangement of waveguides includes a substrate and three waveguides. Each of the three waveguides may be a linear waveguide. A second waveguide is positioned between a first waveguide and a third waveguide. The dimensions and positions of the first, the second, and the third waveguides are specified to substantially eliminate coupling between the first waveguide and the third waveguide over a distance of about 1 millimeter to 2 millimeters along lengths of the first waveguide, the second waveguide, and the third waveguide.
Subwavelength line imaging using plasmonic waveguides
Podoliak, N.; Horak, P.; Prangsma, J.C.; Pinkse, P.W.H.
2015-01-01
We investigate the subwavelength imaging capacity of a 2-D fanned-out plasmonic waveguide array, formed by air channels surrounded by gold metal layers for operation at near-infrared wavelengths, via finite-element simulations. High resolution is achieved on one side of the device by tapering down t
Pollnau, Markus; Orlovic, V.A.; Pachenko, V.; Scherbakov, I.A.
2007-01-01
Our recent results on planar and channel waveguide fabrication and lasers in the dielectric oxide materials Ti:sapphire and rare-earth-ion-doped potassium yttrium double tungstate (KYW) are reviewed. We have employed waveguide fabrication methods such as liquid phase epitaxy and reactive ion etching
Improving plasmonic waveguides coupling efficiency using nanoantennas
DEFF Research Database (Denmark)
Andryieuski, Andrei; Malureanu, Radu; Bouillard, Jean-Sebastien;
2012-01-01
Plasmonic waveguides bear a lot of potential for photonic applications. However, one of the challenges for implementing them in devices is the low coupling efficiency to and from optical fibers. We report on our approach to facilitate the coupling efficiency with the use of metallic nanoantennas....... The classical dipole antenna scheme can be improved by changing the nanoantenna geometry, adding constructive elements such as reflecting bars and mirrors and using arrays of antennas. The modelling designates that the coupling efficiency from a vertical fiber to a plasmonic waveguide can be improved more than...
Forecast analysis of optical waveguide bus performance
Ledesma, R.; Rourke, M. D.
1979-01-01
Elements to be considered in the design of a data bus include: architecture; data rate; modulation, encoding, detection; power distribution requirements; protocol, work structure; bus reliability, maintainability; interterminal transmission medium; cost; and others specific to application. Fiber- optic data bus considerations for a 32 port transmissive star architecture, are discussed in a tutorial format. General optical-waveguide bus concepts, are reviewed. The electrical and optical performance of a 32 port transmissive star bus, and the effects of temperature on the performance of optical-waveguide buses are examined. A bibliography of pertinent references and the bus receiver test results are included.
Liu, X Sherry; Wang, Ji; Zhou, Bin; Stein, Emily; Shi, Xiutao; Adams, Mark; Shane, Elizabeth; Guo, X Edward
2013-07-01
Although high-resolution peripheral quantitative computed tomography (HR-pQCT) has advanced clinical assessment of trabecular bone microstructure, nonlinear microstructural finite element (µFE) prediction of yield strength using a HR-pQCT voxel model is impractical for clinical use due to its prohibitively high computational costs. The goal of this study was to develop an efficient HR-pQCT-based plate and rod (PR) modeling technique to fill the unmet clinical need for fast bone strength estimation. By using an individual trabecula segmentation (ITS) technique to segment the trabecular structure into individual plates and rods, a patient-specific PR model was implemented by modeling each trabecular plate with multiple shell elements and each rod with a beam element. To validate this modeling technique, predictions by HR-pQCT PR model were compared with those of the registered high-resolution micro-computed tomography (HR-µCT) voxel model of 19 trabecular subvolumes from human cadaveric tibia samples. Both the Young's modulus and yield strength of HR-pQCT PR models strongly correlated with those of µCT voxel models (r² = 0.91 and 0.86). Notably, the HR-pQCT PR models achieved major reductions in element number (>40-fold) and computer central processing unit (CPU) time (>1200-fold). Then, we applied PR model µFE analysis to HR-pQCT images of 60 postmenopausal women with (n = 30) and without (n = 30) a history of vertebral fracture. HR-pQCT PR model revealed significantly lower Young's modulus and yield strength at the radius and tibia in fracture subjects compared to controls. Moreover, these mechanical measurements remained significantly lower in fracture subjects at both sites after adjustment for areal bone mineral density (aBMD) T-score at the ultradistal radius or total hip. In conclusion, we validated a novel HR-pQCT PR model of human trabecular bone against µCT voxel models and demonstrated its ability to discriminate vertebral fracture
Giunta, G.
2001-12-01
In the Caribbean Plate deformed margins are found relics of the Mid to Late Cretaceous eo-Caribbean tectonic phases, indicating the occurrence of sub-continental subduction zones with melange formation, and HP/LT metamorphism of ophiolitic rocks, and two main stages of intraoceanic subductions involving the unthickened proto-Caribbean oceanic lithosphere and/or supra-subduction complexes. These two stages are marked by the occurrence of (a) HP/LT metamorphic ophiolites and volcano-plutonic sequences with island-arc tholeiitic (IAT) or calc-alkaline (CA) affinities; (b) unmetamorphosed tonalitic intrusions of CA affinity below the proto-Caribbean thickened oceanic plateau. Since the Late Cretaceous the kinematics of the Caribbean Plate is closely related to the eastward drifting of the proto-Caribbean oceanic plateau (Colombia and Venezuela Basins) that produced both a diachronous tonalitic magmatism from 85-82 Ma, associated with a westward dipping oblique subduction of the proto-Caribbean-Atlantic ocean floor below the plateau, and an opposite dismembering of subduction complexes, of different ages along an E-W trend (North and South Caribbean Margins). This seems to be the consequence of the eastward shifting of both the northern and southern triple junctions, while allowing further bending of the Aves- Lesser Antilles arc. Moreover, the Caribbean oceanic plateau was trapped by different rotation rates of the Chortis, Chorotega and Choco blocks, during the construction of the western plate margin (Central American Isthmus). The previous Mid-Late Cretaceous eo-Caribbean evolution, correspondent to the beginning of the compressional conditions in Central America area, is characterized by sub-continental and/or intraoceanic subduction systems with associated IAT and CA arc magmatism. This simplified kinematic approach falls short in explaining (1) the Early Cretaceous paleogeography and morphology of the margins of the North, South American continents and minor
Exact equivalent straight waveguide model for bent and twisted waveguides
DEFF Research Database (Denmark)
Shyroki, Dzmitry
2008-01-01
Exact equivalent straight waveguide representation is given for a waveguide of arbitrary curvature and torsion. No assumptions regarding refractive index contrast, isotropy of materials, or particular morphology in the waveguide cross section are made. This enables rigorous full-vector modeling o...... of in-plane curved or helically wound waveguides with use of available simulators for straight waveguides without the restrictions of the known approximate equivalent-index formulas....
Hybrid Lithium Niobate and Silicon Photonic Waveguides
Weigel, Peter O; DeRose, Christopher; Pomerene, Andrew T; Starbuck, Andrew L; Lentine, Anthony L; Stenger, Vincent; Mookherjea, Shayan
2015-01-01
We describe a hybrid lithium niobate (LN) / silicon (Si) optical waveguiding platform at near infrared wavelengths. Various optical circuit elements, such as waveguides, bends, and couplers are demonstrated in two hybrid cross sections, A and B, with different LN confinement factors (32% and 90%, respectively) of the fundamental quasi TE mode. Such a large LN confinement factor is achieved with adiabatic tapers that preserve the symmetry of the fundamental quasi TE mode and prevent mode rotation. We find the average propagation loss in cross section B to be 4.3 dB/cm with a standard deviation of 2.1 dB/cm, comparable with a 3 um SiO2 clad (in place of LN) Si waveguide whose average propagation loss was 3.1 dB/cm with a standard deviation of 2.1 dB/cm.
Highly compact optical waveguides with a novel pedestal geometry
Chaudhari, Apurva D.; West, Lawrence C.; Roberts, Charles W.; Lu, Yicheng
1995-05-01
A structure with a large refractive index ratio between waveguide and cladding materials can be fabricated with low scattering losses by using Ge on GaAs waveguides at 10- micron wavelengths. We demonstrate two types of ultra-high confinement (UHC) dielectric waveguides using separate geometries: A ridge and a novel pedestal. Computer simulations using a time-domain finite element,,,method and microwave-scale experiments are performed on both waveguide types. We show a waveguide thickness of 0.18 of the free-space wavelength or greater guide well-confined single-mode light for both geometries. Numerical and experimental values of the effective index agree to better than 0.5%.
Optical waveguide enhanced photovoltaics.
Rühle, Sven; Greenwald, Shlomit; Koren, Elad; Zaban, Arie
2008-12-22
Enhanced light to electric power conversion efficiency of photovoltaic cells with a low absorbance was achieved using waveguide integration. We present a proof of concept using a very thin dye-sensitized solar cell which absorbed only a small fraction of the light at normal incidence. The glass substrate in conjunction with the solar cells reflecting back contact formed a planar waveguide, which lead to more than four times higher conversion efficiency compared to conventional illumination at normal incidence. This illumination concept leads to a new type of multi-junction PV systems based on enforced spectral splitting along the waveguide.
Institute of Scientific and Technical Information of China (English)
Liqing CHEN; Naoyuki Kanetake
2005-01-01
Ingot metallurgy (IM) aluminum has long been the subject and attracted the attention of many metallurgists and textural researchers of materials. Due to the introduction of large amounts of ex situ interfaces, however, the textures in powder metallurgy (PM) processed aluminum has been rarely reported. In this article, a pure aluminum plate was prepared via PM route. The starting billet was first produced with uni-axially cold compaction and flat hot-extrusion and then followed by cold rolling processes. The hot-extruded and cold rolling deformation textures of the pure PM aluminum at 50%, 80% and 90% cold rolling reductions were studied by orientation distribution functions (ODFs) analysis. The finite element polycrystal model (FEPM) was finally utilized to simulate the cold rolling textural evolution at various stages of cold rolling. In FEPM simulation, the initial hot-extruded textures were taken into account as inputs. The results showed that typical β-fiber texture formed in pure PM aluminum with the cold rolling reduction increased till 80%, and there was not much change after excessive cold rolling deformation.Homogeneous slip is not the only deformation mode in PM processed pure aluminum plate at over 80% cold rolling reduction. The experimental results were qualitatively in good agreement with the simulated ones.
Directory of Open Access Journals (Sweden)
J. J. Liou
2014-01-01
Full Text Available The kinematics of the deep rolling tool, contact stress, and induced residual stress in the near-surface material of a flat Ti-6Al-4V alloy plate are numerically investigated. The deep rolling tool is under multiaxis nonlinear motion in the process. Unlike available deep rolling simulations in the open literature, the roller motion investigated in this study includes penetrative and slightly translational motions. A three-dimensional finite element model with dynamic explicit technique is developed to simulate the instantaneous complex roller motions during the deep rolling process. The initial motion of the rollers followed by the penetration motion to apply the load and perform the deep rolling process, the load releasing, and material recovery steps is sequentially simulated. This model is able to capture the transient characteristics of the kinematics on the roller and contacts between the roller and the plate due to variations of roller motion. The predictions show that the magnitude of roller reaction force in the penetration direction starts to decrease with time when the roller motion changes to the deep rolling step and the residual stress distributions in the near-surface material after the material recovery step varies considerably along the roller path.
Omnidirectional optical waveguide
Bora, Mihail; Bond, Tiziana C.
2016-08-02
In one embodiment, a system includes a scintillator material; a detector coupled to the scintillator material; and an omnidirectional waveguide coupled to the scintillator material, the omnidirectional waveguide comprising: a plurality of first layers comprising one or more materials having a refractive index in a first range; and a plurality of second layers comprising one or more materials having a refractive index in a second range, the second range being lower than the first range, a plurality of interfaces being defined between alternating ones of the first and second layers. In another embodiment, a method includes depositing alternating layers of a material having a relatively high refractive index and a material having a relatively low refractive index on a substrate to form an omnidirectional waveguide; and coupling the omnidirectional waveguide to at least one surface of a scintillator material.
Jahani, Saman
2014-01-01
Recently, we introduced a paradigm shift in light confinement strategy and introduced a class of extreme skin depth (e-skid) photonic structures (S. Jahani and Z. Jacob, "Transparent sub-diffraction optics: nanoscale light confinement without metal," Optica 1, 96-100 (2014)). Here, we analytically establish that figures of merit related to light confinement in dielectric waveguides are fundamentally tied to the skin depth of waves in the cladding. We contrast the propagation characteristics of the fundamental mode of e-skid waveguides and conventional waveguides to show that the decay constant in the cladding is dramatically larger in e-skid waveguides, which is the origin of sub-diffraction confinement. Finally, we propose an approach to verify the reduced skin depth in experiment using the decrease in the Goos-H\\"anchen phase shift.
Nanoscale waveguiding methods.
Wang, Chia-Jean; Lin, Lih Y
2007-05-01
While 32 nm lithography technology is on the horizon for integrated circuit (IC) fabrication, matching the pace for miniaturization with optics has been hampered by the diffraction limit. However, development of nanoscale components and guiding methods is burgeoning through advances in fabrication techniques and materials processing. As waveguiding presents the fundamental issue and cornerstone for ultra-high density photonic ICs, we examine the current state of methods in the field. Namely, plasmonic, metal slot and negative dielectric based waveguides as well as a few sub-micrometer techniques such as nanoribbons, high-index contrast and photonic crystals waveguides are investigated in terms of construction, transmission, and limitations. Furthermore, we discuss in detail quantum dot (QD) arrays as a gain-enabled and flexible means to transmit energy through straight paths and sharp bends. Modeling, fabrication and test results are provided and show that the QD waveguide may be effective as an alternate means to transfer light on sub-diffraction dimensions.
Energy Technology Data Exchange (ETDEWEB)
Terremoto, L.A.A.; Zeituni, C.A.; Silva, J.E.R. da; Castanheira, M.; Lucki, G.; Silva, A.T. e; Teodoro, C.A.; Damy, M. de A. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Centro de Engenharia Nuclear]. E-mail: laaterre@ipen.br
2005-07-01
Plate-type fuel elements burned-up inside the core of nuclear research reactors are stored mainly under deionized water of storage pools. When cladding failure occurs in such elements, radioactive fission products are released into the storage pool water. This work proposes a model to describe the release mechanism considering the diffusion through a postulated small cylindrical failure. As a consequence, an analytical expression is obtained for the activity released into the water as a function of the total storage time of a failed fuel plate. The proposed model reproduces the linear increasing of {sup 137}Cs specific activity observed in sipping tests already performed on failed plate-type fuel elements. (author)
Xu, Yanlong
2015-08-01
The coupled mode theory with coupling of diffraction modes and waveguide modes is usually used on the calculations of transmission and reflection coefficients for electromagnetic waves traveling through periodic sub-wavelength structures. In this paper, I extend this method to derive analytical solutions of high-order dispersion relations for shear horizontal (SH) wave propagation in elastic plates with periodic stubs. In the long wavelength regime, the explicit expression is obtained by this theory and derived specially by employing an effective medium. This indicates that the periodical stubs are equivalent to an effective homogenous layer in the long wavelength. Notably, in the short wavelength regime, high-order diffraction modes in the plate and high-order waveguide modes in the stubs are considered with modes coupling to compute the band structures. Numerical results of the coupled mode theory fit pretty well with the results of the finite element method (FEM). In addition, the band structures\\' evolution with the height of the stubs and the thickness of the plate shows clearly that the method can predict well the Bragg band gaps, locally resonant band gaps and high-order symmetric and anti-symmetric thickness-twist modes for the periodically structured plates. © 2015 Elsevier B.V.
A Simple Birefringent Terahertz Waveguide Based on Polymer Elliptical Tube
Institute of Scientific and Technical Information of China (English)
WANG Jing-Li; YAO Jian-Quan; CHEN He-Ming; LI Zhong-Yang
2011-01-01
We propose a simple birefringent terahertz (THz) waveguide which is a polymer elliptical tube with a cross section of elliptical ring structure. It can be achieved by stretching a normal circular-tube in one direction. Simulations based on the full-vector finite element method (FEM) show that this kind of waveguides exhibits high birefringence on a level of 10-2 over a wide THz frequency range. Moreover, as a majority of modal power is trapped in the air core inside the polymer elliptical tube, the THz waveguide guiding loss caused by material absorption can be reduced effectively.
硼-铝强化板的非线性屈曲有限元分析%Nonlinear buckling finite element analysis of stiffened B-Al plates
Institute of Scientific and Technical Information of China (English)
Ezgi GUNAY; Cevdet AYGUN; Yunus Onur YILDIZ
2014-01-01
通过有限元方法（FEA）分析强化复合板的非线性屈曲行为。该模型中硼-铝复合材料由硼基体和嵌入其中的不同形态的Al纤维组成。对片层结构的B-Al矩形板施加横向压缩应力，发现强化纤维对具有不同几何形状板材的屈曲行为有明显影响。建模中采用单向、具有矩形截面的强化纤维。结果表明：加载过程中存在一重要的载荷范围，临界屈曲模式在稳态和非稳态之间反复转变。确定由不同的纤维形态和板材高宽比组成的分叉失稳区域。通过 ANSYS 有限元计算，研究简支边界条件下强化板材的失稳模式，分别得到压应力(σx)与平面收缩(u)以及压应力(σx)与面外挠度(δ)的关系曲线。通过非线性分析，在C1、 C2、 C3和 C4四种形态的纤维中，嵌入C2纤维的板材获得最安全的临界屈服应力。结果表明，FEA非线性屈曲分析可以得到精确的结果。%Nonlinear buckling behavior of stiffened composite B-Al plates was analyzed by means of finite element analysis (FEA) method. In the method, the composite material was taken as B matrix into which Al fibers were embedded in different configurations. The laminated B-Al material in the form of rectangular plates was subjected to lateral compressive loading. It is observed that stiffeners have significant effect on the buckling behavior of plates under compressive loading and for various geometrical configurations. The stiffeners used in the modeling are one-sided and have rectangular cross-sections. It is found that there are physically important loading intervals and the critical buckling modes make transitions back and forth between stable and unstable states. Bifurcation buckling regions resulting from various configurations of fiber orientations and different plate aspect ratios are determined. The whole analysis is performed by using ANSYS finite element computations. Only the buckling patterns of stiffened
Ultra-compact plasmonic waveguide modulators
DEFF Research Database (Denmark)
Babicheva, Viktoriia
-compatible materials, both passive and active plasmonic waveguide components are important. Among other proposed plasmonic waveguides and modulators, the structures where the dielectric core is sandwiched between metal plates have been shown as one of the most compact and efficient layout. Because of the tight mode...... confinement that can be achieved in metal-insulator-metal structures, they provide a base for extremely fast and efficient ultracompact plasmonic devices, including modulators, photodetectors, lasers and amplifiers. The main result of this thesis is a systematic study of various designs of plasmonic......Metal-dielectric interfaces can support the waves known as surface plasmon polaritons, which are tightly coupled to the interface and allow manipulation of light at the nanoscale. Plasmonics as a subject which studies such waves enables the merge between two major technologies: nanometer...
Analysis of wave propagation in periodic 3D waveguides
Schaal, Christoph; Bischoff, Stefan; Gaul, Lothar
2013-11-01
Structural Health Monitoring (SHM) is a growing research field in the realm of civil engineering. SHM concepts are implemented using integrated sensors and actuators to evaluate the state of a structure. Within this work, wave-based techniques are addressed. Dispersion effects for propagating waves in waveguides of different materials are analyzed for various different cross-sections. Since analytical theory is limited, a general approach based on the Waveguide Finite Element Method is applied. Numerical results are verified experimentally.
Supermodes in Coupled Multi-Core Waveguide Structures
2016-04-01
gentle bends . Because modes travel at different group velocities, if three guided modes are assumed to be excited with amplitudes A, B, C and phase φa...mode multi-core waveguide arrays can be strongly affected by angle-dependent cou- plings, leading to different modal field profiles. Analytical...and 37 sites. We begin our analysis by assuming that in all cases, each waveguide element is assumed to be cylindrical (of radius a) and single-moded
Institute of Scientific and Technical Information of China (English)
Yu Yin; Lin-Quan Yao; Yang Cao
2013-01-01
A new efficient meshless method based on the element-free Galerkin method is proposed to analyze the static deformation of thin and thick plate structures in this paper.Using the new 3D shell-like kinematics in analogy to the solid-shell concept of the finite element method,discretization is carried out by the nodes located on the upper and lower surfaces of the structures.The approximation of all unknown field variables is carried out by using the moving least squares (MLS) approximation scheme in the in-plane directions,while the linear interpolation is applied through the thickness direction.Thus,different boundary conditions are defined only using displacements and penalty method is used to entorce the essential boundary conditions.The constrained Galerkin weak form,which incorporates only displacement degrees of freedom (d.o.f.s),is derived.A modified 3D constitutive relationship is adopted in order to avoid or eliminate some self-locking effects.The numeric efficiency of the proposed meshless formulation is illustrated by the numeric examples.
Gap Surface Plasmon Waveguide Analysis
DEFF Research Database (Denmark)
Nielsen, Michael Grøndahl; Bozhevolnyi, Sergey I.
2014-01-01
Plasmonic waveguides supporting gap surface plasmons (GSPs) localized in a dielectric spacer between metal films are investigated numerically and the waveguiding properties at telecommunication wavelengths are presented. Especially, we emphasize that the mode confinement can advantageously...
Low-loss terahertz ribbon waveguides
Yeh, Cavour; Shimabukuro, Fred; Siegel, Peter H.
2005-10-01
The submillimeter wave or terahertz (THz) band (1 mm-100 µm) is one of the last unexplored frontiers in the electromagnetic spectrum. A major stumbling block hampering instrument deployment in this frequency regime is the lack of a low-loss guiding structure equivalent to the optical fiber that is so prevalent at the visible wavelengths. The presence of strong inherent vibrational absorption bands in solids and the high skin-depth losses of conductors make the traditional microstripline circuits, conventional dielectric lines, or metallic waveguides, which are common at microwave frequencies, much too lossy to be used in the THz bands. Even the modern surface plasmon polariton waveguides are much too lossy for long-distance transmission in the THz bands. We describe a concept for overcoming this drawback and describe a new family of ultra-low-loss ribbon-based guide structures and matching components for propagating single-mode THz signals. For straight runs this ribbon-based waveguide can provide an attenuation constant that is more than 100 times less than that of a conventional dielectric or metallic waveguide. Problems dealing with efficient coupling of power into and out of the ribbon guide, achieving low-loss bends and branches, and forming THz circuit elements are discussed in detail. One notes that active circuit elements can be integrated directly onto the ribbon structure (when it is made with semiconductor material) and that the absence of metallic structures in the ribbon guide provides the possibility of high-power carrying capability. It thus appears that this ribbon-based dielectric waveguide and associated components can be used as fundamental building blocks for a new generation of ultra-high-speed electronic integrated circuits or THz interconnects.
Experimental Demonstration of Luneburg Waveguides
Directory of Open Access Journals (Sweden)
Vera N. Smolyaninova
2015-04-01
Full Text Available Transformation optics gives rise to numerous unusual optical devices, such as novel metamaterial lenses and invisibility cloaks. Very recently, Mattheakis et al. (Luneburg lens waveguide networks. J. Opt. 2012, 14, 114006 have suggested theoretical design of an optical waveguide, based on a network of Luneburg lenses, which may be useful in sensing and nonlinear optics applications. Here, we report the first experimental realization of such Luneburg waveguides. We have studied wavelength and polarization dependent performance of the waveguides.
Nanoporous polymer liquid core waveguides
DEFF Research Database (Denmark)
Gopalakrishnan, Nimi; Christiansen, Mads Brøkner; Ndoni, Sokol
2010-01-01
We demonstrate liquid core waveguides defined by UV to enable selective water infiltration in nanoporous polymers, creating an effective refractive index shift Δn=0.13. The mode confinement and propagation loss in these waveguides are presented.......We demonstrate liquid core waveguides defined by UV to enable selective water infiltration in nanoporous polymers, creating an effective refractive index shift Δn=0.13. The mode confinement and propagation loss in these waveguides are presented....
Transparent Conducting Oxides for Infrared Plasmonic Waveguides: ZnO (Preprint)
2014-01-15
AFRL-RY-WP-TP-2014-0009 TRANSPARENT CONDUCTING OXIDES FOR INFRARED PLASMONIC WAVEGUIDES: ZnO (PREPRINT) Monica Allen, Jeffery Allen...CONDUCTING OXIDES FOR INFRARED PLASMONIC WAVEGUIDES: ZnO (PREPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER N...for plasmonic waveguiding applications with an emphasis on highly conducting ZnO . In addition, the paper contains analysis of a set of thin Al-doped
DESIGN OF INTEGRATING WAVEGUIDE BIOSENSOR
The Integrating Waveguide Biosensor allows for rapid and sensitive detection of pathogenic agents, cells and proteins via immunoassay or PCR products. The analytes are captured on the surface of the waveguide and then tagged with fluorescent labels. The waveguides are illuminated by excitation light...
Maldonado, Florian; Mengal, Jan M.; Khan, Shahid H.; Warwick, Peter D.
2011-01-01
Obduction of an ophiolite complex onto the northwestern continental margin of the India plate occurred during the Late Cretaceous to early Paleocene, followed by collision of the ophiolitic complex of the India plate with the Eurasia plate in the Eocene. Lower Eocene marine strata overlie the ophiolitic complex suggesting that suturing was completed by early Eocene time.
GHz modulators in the midinfrared using ultrahigh-confinement waveguides
West, Lawrence C.; Roberts, Charles W.; Piscani, Emil C.; Dubey, Madan; Jones, Kenneth A.; McLane, George F.
1996-01-01
A high speed modulator at low voltage is created in the mid-infrared at 10 micrometers wavelengths by using field-induced absorption on otherwise forbidden intersubband transitions. The physical effects could scale to 1.5 micrometers wavelength light. This modulator is packaged into a unique 350 micrometers long ultra high confinement (UHC) waveguide for low capacitance and high speed. The modulator quantum wells are at the interface of a 2.1 micrometers thick by 3.75 micrometers wide UHC Ge waveguide and the GaAs substrate. The quantum wells have a 17% power coupling to the evanescent fields of the Ge waveguide. A connector to the UHC waveguides, with dimensions much smaller than a free space wavelength, has been developed and demonstrated using diffractive optical element arrays on the back side of the substrate and non-uniform grating couplers. Fields are applied across the modulator quantum wells via an ohmic contact to the side of the Ge waveguide on the top of the QWs. The ground is on the other side of the waveguide and lower towards the substrate. The 7 micrometers wide mesa supporting the quantum wells on the bottom of the Ge waveguide is slightly wider to accommodate a gold electrode.
Active Photonic Crystal Waveguides
DEFF Research Database (Denmark)
Ek, Sara
This thesis deals with the fabrication and characterization of active photonic crystal waveguides, realized in III-V semiconductor material with embedded active layers. The platform offering active photonic crystal waveguides has many potential applications. One of these is a compact photonic...... crystal semiconductor optical amplier. As a step towards such a component, photonic crystal waveguides with a single quantum well, 10 quantum wells and three layers of quantum dots are fabricated and characterized. An experimental study of the amplied spontaneous emission and a implied transmission...... are presented in this thesis. A variation of photonic crystal design parameters are used leading to a spectral shift of the dispersion, it is veried that the observed effects shift accordingly. An enhancement of the amplified spontaneous emission was observed close to the band edge, where light is slowed down...
Waveguide apparatuses and methods
Spencer, James E.
2016-05-10
Optical fiber waveguides and related approaches are implemented to facilitate communication. As may be implemented in accordance with one or more embodiments, a waveguide has a substrate including a lattice structure having a plurality of lattice regions with a dielectric constant that is different than that of the substrate, a defect in the lattice, and one or more deviations from the lattice. The defect acts with trapped transverse modes (e.g., magnetic and/or electric modes) and facilitates wave propagation along a longitudinal direction while confining the wave transversely. The deviation(s) from the lattice produces additional modes and/or coupling effects.
Waveguides for walking droplets
Filoux, Boris; Schlagheck, Peter; Vandewalle, Nicolas
2015-01-01
When gently placing a droplet onto a vertically vibrated bath, a drop can bounce permanently. Upon increasing the forcing acceleration, the droplet is propelled by the wave it generates and becomes a walker with a well defined speed. We investigate the confinement of a walker in different rectangular cavities, used as waveguides for the Faraday waves emitted by successive droplet bounces. By studying the walker velocities, we discover that 1d confinement is optimal for narrow channels. We also propose an analogy with waveguide models based on the observation of the Faraday instability within the channels.
Actively coupled optical waveguides
Alexeeva, N. V.; Barashenkov, I. V.; Rayanov, K.; Flach, S.
2014-01-01
We consider light propagation through a pair of nonlinear optical waveguides with absorption, placed in a medium with power gain. The active medium boosts the in-phase component of the overlapping evanescent fields of the guides, while the nonlinearity of the guides couples it to the damped out-of-phase component creating a feedback loop. As a result, the structure exhibits stable stationary and oscillatory regimes in a wide range of gain-loss ratios. We show that the pair of actively coupled (AC) waveguides can act as a stationary or integrate-and-fire comparator sensitive to tiny differences in their input powers.
Progress in planar optical waveguides
Wang, Xianping; Cao, Zhuangqi
2016-01-01
This book provides a comprehensive description of various slab waveguide structures ranged from graded-index waveguide to symmetrical metal-cladding waveguide. In this book, the transfer Matrix method is developed and applied to analyze the simplest case and the complex generalizations. A novel symmetrical metal-cladding waveguide structure is proposed and systematically investigated for several issues of interest, such as biochemical sensing, Goos-Hänchen shift and the slow light effect, etc. Besides, this book summarizes the authors’ research works on waveguides over the last decade. The readers who are familiar with basic optics theory may find this book easy to read and rather inspiring.
Hwu, Chyanbin
2010-01-01
As structural elements, anisotropic elastic plates find wide applications in modern technology. The plates here are considered to be subjected to not only in plane load but also transverse load. In other words, both plane and plate bending problems as well as the stretching-bending coupling problems are all explained in this book. In addition to the introduction of the theory of anisotropic elasticity, several important subjects have are discussed in this book such as interfaces, cracks, holes, inclusions, contact problems, piezoelectric materials, thermoelastic problems and boundary element a
A symmetric terahertz graphene-based hybrid plasmonic waveguide
Chen, Ming; Sheng, Pengchi; Sun, Wei; Cai, Jianjin
2016-10-01
A graphene-based hybrid plasmonic waveguide (GHPW) structure, which works on the terahertz frequency and includes two identical cylinder robs symmetrically put on each side of graphene sheet with gaps g, has been proposed and investigated. The present waveguide not only significantly improves the propagation length but also maintains a compact mode area, which is due to the coupling between the dielectric waveguide mode and plasmonic mode. The graphene plasmons particularly differ from plasmons in noble metals of which propagation loss can be tuned by adjusting the Fermi energy level or carrier mobility. With a very good Fermi energy level and carrier mobility, a typical propagation length of 26.7 mm, and mode area of optical field of approximately 4 μm2 at 10 THz are achieved. This waveguide structure shows great promise for designing kinds of functional elements in actively tunable integrated optical devices.
Institute of Scientific and Technical Information of China (English)
马牛静; 王荣辉
2011-01-01
Proposed in this paper is a combined plate-beam element method to calculate the local vibration of the orthotropic steel bridge deck with trapezoid stiffened ribs, which is used in the long-span steel bridge. In this method, the top plate and the trapezoid stiffened rib are respectively taken as the flat shell element and the plate-beam element, and the corresponding displacement model is established according to the deformation coordination relationship between the plate and the rib. Moreover, the stiffness matrix of the combined plate-beam element is obtained based on the energy-variation principle, and the consistent mass matrix and the consistent load matrix are obtained based on the shape function of each sub-element. Then, the finite dynamic equilibrium equations are obtained. Finally, a calculation program of dynamic finite element is presented for the combined plate-beam element, and the first 10 consequent natural frequencies are compared with those of the shell finite element, finding that the latters accord well with the formers. Thus, the proposed method proves to be feasible and efficient.%针对大跨度钢桥中采用梯形加劲肋的正交异性钢桥面板,提出一种计算钢桥面板局部振动的组合板梁单元法.其中顶板用平板壳单元分析,梯形加劲肋视为板梁单元,两者的位移模式根据板与肋的变形协调关系建立.组合板梁单元的刚度矩阵通过能量变分原理得到,利用各子单元的形函数可以求得组合板梁单元的一致质量矩阵与一致荷载列阵,进而得到相应的有限元动力平衡方程组.最后编制了组合板梁单元的有限元动力计算程序,将其前10阶自振频率与板壳有限元计算结果进行比较,验证了该方法的可行性与高效性.
复合材料层合板的杂交有限元方法%Hybrid finite element method for laminated composite plate
Institute of Scientific and Technical Information of China (English)
卿光辉; 贾瑞升
2013-01-01
结合复合材料修正后的H-R混合变分原理,直接借助应力-应变关系,推导了新的应力模式,建立了复合材料层合板的杂交等参有限元列式.利用Mathematica语言编程进行数值实例分析,其计算结果与相关文献的精确解以及Abaqus软件建模分析结果对比,实例证明该方法所得到的各个静力学量更接近精确解,并且可用较少的网格划分得到较精确的解.%In this paper based on modified H-R mixed variational principle for composite materials, with the stress -strain relations directly, derivation of a new mode of stress, the hybrid and isoparametric finite element formulation for the laminated composite plate was established. Then the Mathematica was applied for the programming and calculating of a numerical example. Compared with the modeling analysis result using Abaqus software and the exact solution provided in relevant literatures concerning some mechanical quantities, the result obtained in this way is proved to be closer to their exact solutions and satisfactory precision can be obtained with less mesh.
Gratings in polymeric waveguides
Mishakov, G.; Sokolov, V.; Kocabas, A.; Aydinli, A.
2007-04-01
Laser-induced formation of polymer Bragg grating filters for Dense Wavelength Division Multiplexing (DWDM) applications is discussed. Acrylate monomers halogenated with both fluorine and chlorine, which possess absorption losses less than 0.25 dB/cm and wide choice of refractive indices (from 1.3 to 1.5) in the 1.5 μm telecom wavelength region were used. The monomers are highly intermixable thus permitting to adjust the refractive index of the composition within +/-0.0001. Moreover they are photocurable under UV exposure and exhibit high contrast in polymerization. These properties make halogenated acrylates very promising for fabricating polymeric waveguides and photonic circuits. Single-mode polymer waveguides were fabricated on silicon wafers using resistless contact lithography. Submicron index gratings have been written in polymer waveguides using holographic exposure with He-Cd laser beam (325 nm) through a phase mask. Both uniform and apodized gratings have been fabricated. The gratings are stable and are not erased by uniform UV exposure. The waveguide gratings possess narrowband reflection spectra in the 1.5 μm wavelength region of 0.4 nm width, nearly rectangular shape of the stopband and reflectivity R > 99%. The fabricated Bragg grating filters can be used for multiplexing/demultiplexing optical signals in high-speed DWDM optical fiber networks.
Giovannetti, Vittorio; Lloyd, Seth; Maccone, Lorenzo; Shapiro, Jeffrey H.
2003-01-01
We calculate the communication capacity of a broadband electromagnetic waveguide as a function of its spatial dimensions and input power. We analyze the two cases in which either all the available modes or only a single directional mode are employed. The results are compared with those for the free space bosonic channel.
Directory of Open Access Journals (Sweden)
Wang Chia-Jean
2007-01-01
Full Text Available AbstractWhile 32 nm lithography technology is on the horizon for integrated circuit (IC fabrication, matching the pace for miniaturization with optics has been hampered by the diffraction limit. However, development of nanoscale components and guiding methods is burgeoning through advances in fabrication techniques and materials processing. As waveguiding presents the fundamental issue and cornerstone for ultra-high density photonic ICs, we examine the current state of methods in the field. Namely, plasmonic, metal slot and negative dielectric based waveguides as well as a few sub-micrometer techniques such as nanoribbons, high-index contrast and photonic crystals waveguides are investigated in terms of construction, transmission, and limitations. Furthermore, we discuss in detail quantum dot (QD arrays as a gain-enabled and flexible means to transmit energy through straight paths and sharp bends. Modeling, fabrication and test results are provided and show that the QD waveguide may be effective as an alternate means to transfer light on sub-diffraction dimensions.
Fluitman, J.; Popma, Th.
1986-01-01
An overview of the field of optical waveguide sensors is presented. Some emphasis is laid on the development of a single scheme under which the diversity of sensor principles can be arranged. First three types of sensors are distinguished: intrinsic, extrinsic and active. Next, two steps are disting
Amplifier Module for 260-GHz Band Using Quartz Waveguide Transitions
Padmanabhan, Sharmila; Fung, King Man; Kangaslahti, Pekka P.; Peralta, Alejandro; Soria, Mary M.; Pukala, David M.; Sin, Seth; Samoska, Lorene A.; Sarkozy, Stephen; Lai, Richard
2012-01-01
Packaging of MMIC LNA (monolithic microwave integrated circuit low-noise amplifier) chips at frequencies over 200 GHz has always been problematic due to the high loss in the transition between the MMIC chip and the waveguide medium in which the chip will typically be used. In addition, above 200 GHz, wire-bond inductance between the LNA and the waveguide can severely limit the RF matching and bandwidth of the final waveguide amplifier module. This work resulted in the development of a low-loss quartz waveguide transition that includes a capacitive transmission line between the MMIC and the waveguide probe element. This capacitive transmission line tunes out the wirebond inductance (where the wire-bond is required to bond between the MMIC and the probe element). This inductance can severely limit the RF matching and bandwidth of the final waveguide amplifier module. The amplifier module consists of a quartz E-plane waveguide probe transition, a short capacitive tuning element, a short wire-bond to the MMIC, and the MMIC LNA. The output structure is similar, with a short wire-bond at the output of the MMIC, a quartz E-plane waveguide probe transition, and the output waveguide. The quartz probe element is made of 3-mil quartz, which is the thinnest commercially available material. The waveguide band used is WR4, from 170 to 260 GHz. This new transition and block design is an improvement over prior art because it provides for better RF matching, and will likely yield lower loss and better noise figure. The development of high-performance, low-noise amplifiers in the 180-to- 700-GHz range has applications for future earth science and planetary instruments with low power and volume, and astrophysics array instruments for molecular spectroscopy. This frequency band, while suitable for homeland security and commercial applications (such as millimeter-wave imaging, hidden weapons detection, crowd scanning, airport security, and communications), also has applications to
Characterization of low-loss waveguides and devices for terahertz radiation
Rahman, B. M. Azizur; Markides, Christos; Uthman, Muhammad; Quadir, Anita; Kejalakshmy, Namassivayane; Themistos, Christos
2014-03-01
A rigorous full-vectorial modal solution approach based on the finite element method is used to find the propagation properties of terahertz (THz) waveguides, such as photonic crystal fibers, quantum cascaded lasers, plasmonic waveguides, power splitters, and narrow-band filters. Design approaches to reduce the modal loss due to the material and leakage loss in photonic crystal fibers and in metal-coated hollow-glass plasmonic waveguides have also been considered. The plasmonic confinement and gain threshold of quantum cascaded lasers used as THz sources and the chromatic dispersion in plasmonic waveguides are also presented.
Waveguide effect under 'antiguiding' conditions in graded anisotropic media
Kozlov, A. V.; Mozhaev, V. G.; Zyryanova, A. V.
2010-02-01
A new wave confinement effect is predicted in graded crystals with a concave slowness surface under conditions of growth of the phase velocity with decreasing distance from the waveguide axis. This finding overturns the common notion about the guiding and 'antiguiding' profiles of wave velocity in inhomogeneous media. The waveguide effect found is elucidated by means of ray analysis and particular exact wave solutions. The exact solution obtained for localized flexural waves in thin plates of graded cubic and tetragonal crystals confirms the predicted effect. Since this solution is substantially different with respect to the existence conditions from all others yet reported, and it cannot be deduced from the previously known results, the predicted waves can be classified as a new type of waveguide mode in graded anisotropic media. Although the concrete calculations are given in the article for acoustic waves, its general predictions are expected to be valid for waves of various natures, including spin, plasma, and optical waves.
A transversely localized light in a waveguide: the analytical solution and its potential application
Arslanov, Narkis M.; Moiseev, Sergey A.; Kamli, Ali A.
2017-02-01
Investigation of light in waveguide structures is a topical modern problem that has long-standing historical roots. A parallel-plate waveguide is a basic model in these studies and is intensively used in numerous investigations of nano-optics, integrated circuits and nanoplasmonics. In this letter we have first found an approximate analytical solution which describes the light modes with high accuracy in the subwavelength waveguides. The solution provides a way of obtaining a clear understanding of the light properties within the broadband spectral range in the waveguide with various physical parameters. The potential of the analytical solution for studies of light fields in the waveguides of nano-optics and nanoplasmonics has also been discussed.
Experimental investigation of plasmofluidic waveguides
Energy Technology Data Exchange (ETDEWEB)
Ku, Bonwoo; Kwon, Min-Suk, E-mail: mskwon@unist.ac.kr [School of Electrical and Computer Engineering, UNIST, 50 UNIST-gil, Eonyang-eup, Ulju-gun, Ulsan 689-798 (Korea, Republic of); Shin, Jin-Soo [Department of Electrical Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)
2015-11-16
Plasmofluidic waveguides are based on guiding light which is strongly confined in fluid with the assistance of a surface plasmon polariton. To realize plasmofluidic waveguides, metal-insulator-silicon-insulator-metal (MISIM) waveguides, which are hybrid plasmonic waveguides fabricated using standard complementary metal-oxide-semiconductor technology, are employed. The insulator of the MISIM waveguide is removed to form 30-nm-wide channels, and they are filled with fluid. The plasmofluidic waveguide has a subwavelength-scale mode area since its mode is strongly confined in the fluid. The waveguides are experimentally characterized for different fluids. When the refractive index of the fluid is 1.440, the plasmofluidic waveguide with 190-nm-wide silicon has propagation loss of 0.46 dB/μm; the coupling loss between it and an ordinary silicon photonic waveguide is 1.79 dB. The propagation and coupling losses may be reduced if a few fabrication-induced imperfections are removed. The plasmofluidic waveguide may pave the way to a dynamically phase-tunable ultracompact device.
Blockage, trapping and waveguide modes for flexural waves in a semi-infinite double grating
Jones, Ian S; Movchan, Alexander B
2015-01-01
The paper presents a novel view on the scattering of a flexural wave in a Kirchhoff plate by a semi-infinite discrete system. Blocking and channelling of flexural waves are of special interest. A quasi-periodic two-source Green's function is used in the analysis of the waveguide modes. An additional "effective waveguide" approximation has been constructed. Comparisons are presented for these two methods in addition to an analytical solution for a finite truncated system.
Von Der Handt, A.; Rahn, M. K. W.; Wang, L. X.; Marks, M. A. W.
2014-12-01
The role of volatiles in the petrogenesis of alkaline intra-plate magmas has been the subject of an increasing number of experimental studies. The study of naturally occurring rocks and their volatile contents is often complicated by syn- and post-eruptive degassing and alteration processes. Minerals that incorporate volatiles into their structure such as apatites are often more faithful recorders of the pre-eruptive volatile budget. The Hegau volcanic field in Southwest Germany is part of the Central European Volcanic Province, lies around 60-70 km to the east of the Upper Rhine graben and of Miocene age. Three main lithological units can be distinguished (1) olivine melilites (2) phonolites and (3) the "Deckentuff" series referring to a series of diatreme-filling pipe breccias and lapilli tuff layers. Carbonatites occur subordinately in the Hegau province. Earlier radiometric age dating suggested distinct phases of volcanic activity of Deckentuffs, melilites and phonolites with little overlap, but new apatite fission-track and (U-Th)/He age data suggest a synchronous activity. Apatite is an abundant accessory phase in the Deckentuff and phonolite series and we investigated its major, trace and volatile element composition by EPMA, SIMS and cathodoluminescence imaging. Pronounced core-rim zoning of apatite in places attests that diffusional equilibration was very limited and they likely retained their primary compositions. This allows us to trace the entire magmatic evolution of the Hegau province from its most primitive to most evolved products as well as resolve it in time by combining age dating with compositional analysis. Apatite compositions fall along the OH-F join with low Cl-contents (<0.5 wt%). Volatile contents (Cl, OH, S) are highest in most primitive compositions and decrease with further evolution while F increases. Multiple magmatic cycles can be discerned with a general trend to the more evolved phonolite compositions toward the end of volcanic
The Influence Of Infinite Impedance Flanges On The Electromagnetic Field Of A Plane Waveguide
Directory of Open Access Journals (Sweden)
Jean-François D. Essiben
2015-02-01
Full Text Available The problem of analysis of the electromagnetic field behaviour from the open end of the parallel-plate waveguide with infinite impedance flanges is theoretically investigated. The case with the absence of impedance flanges is also considered. Furthermore, we take into account particular features of the waveguide edges. The effects of the impedance flanges and the edge features on the electromagnetic field and the radiation patterns of a plane waveguide with flanges are demonstrated. The method of moments (MoM technique which was used to solve the integral equations is presented along with the numerical results.
Millimeter-wave waveguiding using photonic band structures
Eliyahu, Danny; Sadovnik, Lev S.; Manasson, Vladimir A.
2000-07-01
Current trends in device miniaturization and integration, especially in the development of microwave monolithic integrated circuits, calls for flexible, arbitrarily shaped and curved interconnects. Standard dielectric waveguides and microstrip lines are subject to prohibitive losses and their functionality is limited because of their unflexible structures. The problem is addressed by confining the wave- guiding path in a substrate with a Photonic Band Gap structure in a manner that will result in the guided mode being localized within the band gap. Two devices implementing Photonic Band Structures for millimeter waves confinement are presented. The first waveguide is a linear defect in triangular lattice created in a silicon slab (TE mode). The structure consists of parallel air holes of circular cross sections. The silicon was laser drilled to create the 2D crystal. The second device consists of alumina rods arranged in a triangular lattice, surrounded by air and sandwiched between two parallel metal plates (TM mode). Electromagnetic wave (W-band) confinement was obtained in both devices for straight and bent waveguides. Three branch waveguides (intersecting line defects) was studied as well. Measurements confirmed the lowloss waveguide confinement property of the utilizing Photonic Band Gap structure. This structure can find applications in power combiner/splitter and other millimeter wave devices.
Hussain, Mozammil; Natarajan, Raghu N; Fayyazi, Amir H; Braaksma, Brian R; Andersson, Gunnar B J; An, Howard S
2009-12-01
Anterior corpectomy and reconstruction with bone graft and a rigid screw-plate construct is an established procedure for treatment of cervical neural compression. Despite its reliability in relieving symptoms, there is a high rate of construct failure, especially in multilevel cases. There has been no study evaluating the biomechanical effects of screw angulation on construct stability; this study investigates the C4-C7 construct stability and load-sharing properties among varying screw angulations in a rigid plate-screw construct. A finite element model of a two-level cervical corpectomy with static anterior cervical plate. A three-dimensional finite element (FE) model of an intact C3-T1 segment was developed and validated. From this intact model, a fusion model (two-level [C5, C6] anterior corpectomy) was developed and validated. After corpectomy, allograft interbody fusion with a rigid anterior screw-plate construct was created from C4 to C7. Five additional FE models were developed from the fusion model corresponding to five different combinations of screw angulations within the vertebral bodies (C4, C7): (0 degrees, 0 degrees), (5 degrees, 5 degrees), (10 degrees, 10 degrees), (15 degrees, 15 degrees), and (15 degrees, 0 degrees). The fifth fusion model was termed as a hybrid fusion model. The stability of a two-level corpectomy reconstruction is not dependent on the position of the screws. Despite the locked screw-plate interface, some degree of load sharing is transmitted to the graft. The load seen by the graft and the shear stress at the bone-screw junction is dependent on the angle of the screws with respect to the end plate. Higher stresses are seen at more divergent angles, particularly at the lower level of the construct. This study suggests that screw divergence from the end plates not only increases load transmission to the graft but also predisposes the screws to higher shear forces after corpectomy reconstruction. In particular, the inferior screw
Nonlocal effects in a hybrid plasmonic waveguide for nanoscale confinement.
Huang, Qiangsheng; Bao, Fanglin; He, Sailing
2013-01-28
The effect of nonlocal optical response is studied for a novel silicon hybrid plasmonic waveguide (HPW). Finite element method is used to implement the hydrodynamic model and the propagation mode is analyzed for a hybrid plasmonic waveguide of arbitrary cross section. The waveguide has an inverted metal nano-rib over a silicon-on-insulator (SOI) structure. An extremely small mode area of~10⁻⁶λ² is achieved together with several microns long propagation distance at the telecom wavelength of 1.55 μm. The figure of merit (FoM) is also improved in the same time, compared to the pervious hybrid plasmonic waveguide. We demonstrate the validity of our method by comparing our simulating results with some analytical results for a metal cylindrical waveguide and a metal slab waveguide in a wide wavelength range. For the HPW, we find that the nonlocal effects can give less loss and better confinement. In particular, we explore the influence of the radius of the rib's tip on the loss and the confinement. We show that the nonlocal effects give some new fundamental limitation on the confinement, leaving the mode area finite even for geometries with infinitely sharp tips.
Waveguide submillimeter mixers
Goldsmith, Paul F.; Erickson, Neal R.
1986-01-01
A waveguide Schottky barrier diode mixer, which in preliminary tests has yielded a single sideband receiver noise temperature of 4300 K at 692 GHz, when cooled to 77 K is presented. Further refinements and operation at 20 K should produce a significant improvement in performance. From a system point of view, the very high efficiency of the radiation pattern produced by the conical feedhorn with cylindrical corrector mirror enhances the effective sensitivity by a factor of 1.5 to 2 compared to open-structure corner-reflector systems. A second-harmonic mixer for 557 GHz, also in the fundamental mode rectangular waveguide was developed. When combined with a frequency-tripled Gunn oscillator, this makes an extremely compact and lightweight submillimeter radiometer.
Miniaturized dielectric waveguide filters
Sandhu, Muhammad Y.; Hunter, Ian C.
2016-10-01
Design techniques for a new class of integrated monolithic high-permittivity ceramic waveguide filters are presented. These filters enable a size reduction of 50% compared to air-filled transverse electromagnetic filters with the same unloaded Q-factor. Designs for Chebyshev and asymmetric generalised Chebyshev filter and a diplexer are presented with experimental results for an 1800 MHz Chebyshev filter and a 1700 MHz generalised Chebyshev filter showing excellent agreement with theory.
Institute of Scientific and Technical Information of China (English)
王在峰; 侯保荣; 孙虎元; 宋积文; 陈胜利; 张大勇
2015-01-01
To supply a cathodic protection system for steel plates used to protect old wharfs, and find out distributions of e-lectrical field in cathodic protection system of steel plates in complex conditions, an ideal model of cathodic protection system of steel palates is established.Finite element simulation instead of traditional experiential estimate is used in calculation for cathodic protection system of steel plates under different conditions.Distributions of electrical field in cathodic protection system of steel plates in different corrosion medias are given, as well as the distributions of electrical field between two influenced steel plates.%为了给老式靠船码头的护堤钢板添加阴极保护系统，为护堤钢板阴极保护设计提供依据，建立护堤钢板阴极保护体系的理想模型，用有限元仿真代替传统经验估算法对不同情况下护堤钢板的阴极保护体系进行模拟计算，找到护堤钢板在不同的腐蚀介质及钢板之间相互影响时的阴极保护电场的分布规律。
Anisotropic and nonlinear optical waveguides
Someda, CG
1992-01-01
Dielectric optical waveguides have been investigated for more than two decades. In the last ten years they have had the unique position of being simultaneously the backbone of a very practical and fully developed technology, as well as an extremely exciting area of basic, forefront research. Existing waveguides can be divided into two sets: one consisting of waveguides which are already in practical use, and the second of those which are still at the laboratory stage of their evolution. This book is divided into two separate parts: the first dealing with anisotropic waveguides, an
Waveguide mutually pumped phase conjugators
James, S. W.; Youden, K.E.; Jeffrey, P. M.; EASON, R. W.; Chandler, P.J.; Zhang, L.; Townsend, P.D.
1993-01-01
The operation of the Bridge Mutually Pumped Phase Conjugator is reported in a planar waveguide structure in photorefractive BaTiO3. The waveguide was fabricated by the technique of ion implantation. using 1.5 MeV H+ at a dose of 10^16 ions/cm^2. An order of magnitude decrease in response time is observed in the waveguide as compared to typical values obtained in bulk crystals, probably resulting from a combination of the optical confinement within the waveguide, and possibly modification of t...
Institute of Scientific and Technical Information of China (English)
张迅; 张健强; 李小珍
2015-01-01
在平截面的假定条件下，通过建立梁—板混合单元有限元模型，采用车—线—桥耦合振动分析得到桥梁高频振动响应，再采用声学边界元法分析桥梁结构噪声。以32 m混凝土简支箱梁为例，讨论了不同的梁—板混合模型对计算精度和效率的影响，并与现场试验结果进行对比。由此验证了：在梁—板混合有限元模型中，跨中板单元区域的长度取5倍以上梁高时，桥梁高频振动和结构噪声仿真值均能取得良好的精度，计算效率可提高70%左右。桥梁振动和结构噪声的峰值频率范围为40 Hz～80 Hz，在梁侧传播时具有一定的指向性。采用梁—板混合单元模型计算得到30 m范围内的结构噪声与全板单元模型计算结果基本一致，但在30 m范围外，前者的计算值要比后者小2 dB(Lin)左右。因而，梁—板混合单元模型可有助于提高桥梁车致振动和噪声分析的效率。%Computational efficiency is a bottleneck in calculating train-induced high-frequency bridge vibration and as-sociated structure-borne noise. In this paper, based on the plane cross-section assumption, the beam-plate hybrid elements were introduced and the train-track-bridge coupling finite element model was built for analyzing the high-frequency vibra-tion response of the bridge. Then, the acoustical boundary element method was used to compute the structure-borne noise. Taking a 32 m simply-supported box-girder as an example, the computational efficiency and accuracy were investigated through different beam-plate combination models. A field test was also carried out for verification. Results show that if the length of the plate-element region exceeds five times of the height of the girder, the computational efficiency can be raised by 70%without loss of accuracy in comparison with the conventional finite element analysis with plate elements. The domi-nant frequency of bridge vibration and the
Modes and exceptional points in waveguides with impedance boundary conditions
Midya, Bikashkali
2016-01-01
A planar waveguide with impedance boundary, composed of non-perfect metallic plates, and with passive or active dielectric filling is considered. We show the possibility of selective mode guiding and amplification when homogeneous pump is added to the dielectric, and analyze differences in TE and TM mode propagation. Such a non-conservative system is also shown to feature exceptional points, for specific and experimentally tunable parameters, which are described for a particular case of transparent dielectric.
Origami - Folded Plate Structures
Buri, Hans Ulrich
2010-01-01
This research investigates new methods of designing folded plate structures that can be built with cross-laminated timber panels. Folded plate structures are attractive to both architects and engineers for their structural, spatial, and plastic qualities. Thin surfaces can be stiffened by a series of folds, and thus not only cover space, but also act as load bearing elements. The variation of light and shadow along the folded faces emphasizes the plas...
Multi Reflection of Lamb Wave Emission in an Acoustic Waveguide Sensor
Directory of Open Access Journals (Sweden)
Leonhard Michael Reindl
2013-02-01
Full Text Available Recently, an acoustic waveguide sensor based on multiple mode conversion of surface acoustic waves at the solid—liquid interfaces has been introduced for the concentration measurement of binary and ternary mixtures, liquid level sensing, investigation of spatial inhomogenities or bubble detection. In this contribution the sound wave propagation within this acoustic waveguide sensor is visualized by Schlieren imaging for continuous and burst operation the first time. In the acoustic waveguide the antisymmetrical zero order Lamb wave mode is excited by a single phase transducer of 1 MHz on thin glass plates of 1 mm thickness. By contact to the investigated liquid Lamb waves propagating on the first plate emit pressure waves into the adjacent liquid, which excites Lamb waves on the second plate, what again causes pressure waves traveling inside the liquid back to the first plate and so on. The Schlieren images prove this multi reflection within the acoustic waveguide, which confirms former considerations and calculations based on the receiver signal. With this knowledge the sensor concepts with the acoustic waveguide sensor can be interpreted in a better manner.
Multi reflection of Lamb wave emission in an acoustic waveguide sensor.
Schmitt, Martin; Olfert, Sergei; Rautenberg, Jens; Lindner, Gerhard; Henning, Bernd; Reindl, Leonhard Michael
2013-02-27
Recently, an acoustic waveguide sensor based on multiple mode conversion of surface acoustic waves at the solid-liquid interfaces has been introduced for the concentration measurement of binary and ternary mixtures, liquid level sensing, investigation of spatial inhomogenities or bubble detection. In this contribution the sound wave propagation within this acoustic waveguide sensor is visualized by Schlieren imaging for continuous and burst operation the first time. In the acoustic waveguide the antisymmetrical zero order Lamb wave mode is excited by a single phase transducer of 1 MHz on thin glass plates of 1 mm thickness. By contact to the investigated liquid Lamb waves propagating on the first plate emit pressure waves into the adjacent liquid, which excites Lamb waves on the second plate, what again causes pressure waves traveling inside the liquid back to the first plate and so on. The Schlieren images prove this multi reflection within the acoustic waveguide, which confirms former considerations and calculations based on the receiver signal. With this knowledge the sensor concepts with the acoustic waveguide sensor can be interpreted in a better manner.
Focusing on Plates: Controlling Guided Waves using Negative Refraction
2015-01-01
Elastic waves are guided along finite structures such as cylinders, plates, or rods through reflection, refraction, and mode conversion at the interfaces. Such wave propagation is ubiquitous in the world around us, and studies of elastic waveguides first emerged in the later part of the 19th century. Early work on elastic waveguides revealed the presence of backward propagating waves, in which the phase velocity and group velocity are anti-parallel. While backward wave propagation exists natu...
Low crosstalk Arrayed Waveguide Grating with Cascaded Waveguide Grating Filter
Energy Technology Data Exchange (ETDEWEB)
Deng Yang; Liu Yuan; Gao Dingshan, E-mail: dsgao@mail.hust.edu.cn [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China)
2011-02-01
We propose a highly compact and low crosstalk arrayed waveguide grating (AWG) with cascaded waveguide grating (CWGF). The side lobes of the silicon nanowire AWG, which are normally introduced by fabrication errors, can be effectively suppressed by the CWGF. And the crosstalk can be improved about 15dB.
Multimode waveguide speckle patterns for compressive sensing.
Valley, George C; Sefler, George A; Justin Shaw, T
2016-06-01
Compressive sensing (CS) of sparse gigahertz-band RF signals using microwave photonics may achieve better performances with smaller size, weight, and power than electronic CS or conventional Nyquist rate sampling. The critical element in a CS system is the device that produces the CS measurement matrix (MM). We show that passive speckle patterns in multimode waveguides potentially provide excellent MMs for CS. We measure and calculate the MM for a multimode fiber and perform simulations using this MM in a CS system. We show that the speckle MM exhibits the sharp phase transition and coherence properties needed for CS and that these properties are similar to those of a sub-Gaussian MM with the same mean and standard deviation. We calculate the MM for a multimode planar waveguide and find dimensions of the planar guide that give a speckle MM with a performance similar to that of the multimode fiber. The CS simulations show that all measured and calculated speckle MMs exhibit a robust performance with equal amplitude signals that are sparse in time, in frequency, and in wavelets (Haar wavelet transform). The planar waveguide results indicate a path to a microwave photonic integrated circuit for measuring sparse gigahertz-band RF signals using CS.
Realization of Tapered Waveguide by Stretching the Rod Waveguide
Institute of Scientific and Technical Information of China (English)
XIA Ke-yu; YU Rong-jin; MENG Hua-mao
2004-01-01
By stretching the rod waveguide with different velocities in opposite directions,the tapered waveguide can be fabricated.In condition of taking no account of volume expansion caused by heating and under the assumptions of volume conservation,the rod waveguide can be stretched freely in the heated region without being stretched outside of the heated region. A model,which shows the relation of the transition shape and the two factors,that is the ratio of two velocity and the heated region length,is presented for the shape of the taper transition through mathematic deduction.Based on this model,a desired tapered waveguide can be fabricated.The tapered waveguide are widely used for fabricating tapered fiber couplers and sensors.In addition,the conclusion can be used for fabricating fused fiber coupler.
Compact surface plasmonic waveguide component for integrated optical processor
Gogoi, Nilima; Sahu, Partha Pratim
2015-06-01
A compact surface plasmonic two mode interference waveguide component having silicon core and silver and GaAsInP side cladding is proposed for optical processor elements. Coupling operation is obtained by using index modulation of GaAsInP cladding with applied optical pulse.
Tailoring Dispersion properties of photonic crystal waveguides by topology optimization
DEFF Research Database (Denmark)
Stainko, Roman; Sigmund, Ole
2007-01-01
The paper describes a systematic method for the tailoring of dispersion properties of slab-based photonic crystal waveguides. The method is based on the topology optimization method which consists in repeated finite element frequency domain analyzes, analytical sensitivity analyzes and gradient...
Institute of Scientific and Technical Information of China (English)
陈宁; 于德介; 吕辉; 夏百战
2014-01-01
In order to improve the accuracy of simulation analysis of plate structural-acoustic coupled systems,the finite element-least square point interpolation method (FE-LSPIM)was extended to solve plate structural -acoustic coupled problems and a coupled FE-LSPIM for plate structural-acoustic coupled systems was proposed.With the proposed method,the shape functions of the finite element method and the least square point interpolation were used for local approximation,the element-compatibility of the finite element method and the quadratic polynomial completeness of LSPIM were inherited.Thus,the accuracy of simulation analysis could be improved.Numerical example of a box structural-acoustic coupled model was presented.Its results showed that using FE-LSPIMachieves a higher accuracy,compared with using FEMand smoothed FEMfor simulation of plate structural -acoustic coupled problems.%为提高板结构-声场耦合分析的计算精度，将有限元-最小二乘点插值法（Finite Element-Least Square Point Interpolation Method，FE-LSPIM）推广到板结构-声场耦合问题的分析中，提出了板结构-声场耦合问题分析的 FE-LSPIM/FE-LSPIM方法，推导了 FE-LSPIM/FE-LSPIM分析板结构-声场耦合问题的计算公式。FE-LSPIM/FE-LSPIM方法应用有限元单元形函数和最小二乘点插值法进行局部逼近，继承了有限元法的单元兼容性和最小二乘插值法的二次多项式完备性，提高了计算精度。以一六面体声场-结构耦合模型为研究对象进行分析，结果表明，与板结构-声场耦合问题分析的 FEM/FEM和光滑有限元/有限元（Smoothed Finite Element Method /Finite Element Method，SFEM/FEM）相比，FE-LSPIM/FE-LSPIM在分析板结构-声场耦合问题时具有更高的精度。
Actively coupled optical waveguides
Alexeeva, N. V.; Barashenkov, I. V.; Rayanov, K.; Flach, S.
2013-01-01
We consider light propagation through a pair of nonlinear optical waveguides with absorption, placed in a medium with power gain. The active medium boosts the in-phase component of the overlapping evanescent fields of the guides, while the nonlinearity of the guides couples it to the damped out-of-phase component creating a feedback loop. As a result, the structure exhibits stable stationary and oscillatory regimes in a wide range of gain-loss ratios. We show that the pair of actively-coupled...
Tunable waveguide bends with graphene-based anisotropic metamaterials
Chen, Zhao-xian
2016-01-15
We design tunable waveguide bends filled with graphene-based anisotropic metamaterials to achieve a nearly perfect bending effect. The anisotropic properties of the metamaterials can be described by the effective medium theory. The nearly perfect bending effect is demonstrated by finite element simulations of various structures with different bending curvatures and shapes. This effect is attributed to zero effective permittivity along the direction of propagation and matched effective impedance at the interfaces between the bending part and the dielectric waveguides. We envisage that the design will be applicable in the far-infrared and terahertz frequency ranges owing to the tunable dielectric responses of graphene.
Tunable waveguide bends with graphene-based anisotropic metamaterials
Chen, Zhao-xian; Chen, Ze-guo; Ming, Yang; Wu, Ying; Lu, Yan-qing
2016-02-01
We design tunable waveguide bends filled with graphene-based anisotropic metamaterials to achieve a nearly perfect bending effect. The anisotropic properties of the metamaterials can be described by the effective medium theory. The nearly perfect bending effect is demonstrated by finite element simulations of various structures with different bending curvatures and shapes. This effect is attributed to zero effective permittivity along the direction of propagation and matched effective impedance at the interfaces between the bending part and the dielectric waveguides. We envisage that the design will be applicable in the far-infrared and terahertz frequency ranges owing to the tunable dielectric responses of graphene.
Near-field characterization of plasmonic waveguides
DEFF Research Database (Denmark)
Zenin, Volodymyr
2014-01-01
This PhD thesis presents investigation of plasmonic waveguides and waveguiding components by means of scanning near-field optical microscopy characterizations, far-field optical observations, and numerical simulations. The plasmonic waveguiding attracts huge interest due to several reasons: 1...... simply by changing geometric parameters of the waveguide, keeping in mind the trade-off between confinement and propagation losses. A broad variety of plasmonic waveguides and waveguide components, including antennas for coupling the light in/out of the waveguide, requires correspondent characterization...
Analysis and optimization of waveguide multiapplicator hyperthermia systems.
Boag, A; Leviatan, Y; Boag, A
1993-09-01
A method is proposed for determining the excitation coefficients of an antenna array operating in a large rectangular waveguide and used as a hyperthermia system. The excitation coefficients of the array elements are optimized for attaining an improved specific absorption rate (SAR) distribution around a deep-seated tumor. The method is applied to a two-dimensional problem of a piecewise homogeneous post in a waveguide representing a section of the human torso. The array is operating below the cutoff frequency of the dominant mode of the waveguide. Numerical simulations have been performed to check the effectiveness of this approach. The results show that by using the proposed optimization method, SAR distributions can be improved.
Variational analysis of eigenmodes of integrated optical waveguides and applications
Institute of Scientific and Technical Information of China (English)
祝宁华
1995-01-01
An iterative procedure is proposed for the variational analysis of Ti:LiNbO3 optical waveguides. A trial solution for the dominant electric field profile of arbitrary-order eigenmodes in strip waveguides and two coupled waveguides is proposed and its parameters are determined using the variational method. The results calculated using this method agree well with those obtained using the finite-element method. The present method has been used to check the accuracy of the effective index method as well as a quasi-analytical technique based on the effective index method. The results show that the effective index method is generally accurate for the fundamental mode and becomes less accurate for higher-order vertical modes.
Compact silicon multimode waveguide spectrometer with enhanced bandwidth
Piels, Molly; Zibar, Darko
2017-01-01
Compact, broadband, and high-resolution spectrometers are appealing for sensing applications, but difficult to fabricate. Here we show using calibration data a spectrometer based on a multimode waveguide with 2 GHz resolution, 250 GHz bandwidth, and a 1.6 mm × 2.1 mm footprint. Typically, such spectrometers have a bandwidth limited by the number of modes supported by the waveguide. In this case, an on-chip mode-exciting element is used to repeatably excite distinct collections of waveguide modes. This increases the number of independent spectral channels from the number of modes to this number squared, resulting in an extension of the usable range. PMID:28290537
Dupuis, Alexandre
In this thesis we have explored a wide variety of dielectric waveguides that rely on many different waveguiding mechanisms to guide THz (far-infrared) radiation. We have explored both theoretically and experimentally a large number of waveguide designs with the aim of reducing propagation and bending losses. The different waveguides can be classified into two fundamentally different strategies for reducing the propagation loss: small-core single-mode evanescent-field fibers or large hollow-core multi-mode tubes. Our focus was first set on exploring the small-core evanescent-field fiber strategy for reducing propagation losses. Following initial theoretical work in our group, much effort was spent on the fabrication and measurement of evanescent porous subwavelength diameter plastic fibers, in an attempt to further reduce the propagation losses. The fabrication of such fibers is a challenge and many novel techniques were devised to enable fiber drawing without hole collapse. The first method sealed the holes of an assembly of polymer tubes and lead to fibers of relatively low porosity (˜25% air within the core) due to reduction in hole size during fiber drawing. The second method was a novel sacrificial polymer technique whereby drawing a completely solid fiber prevented any hole collapse and the subsequent dissolution of the sacrificial polymer revealed the holes in the fiber. The third method was a combination of preform casting using glass molds and drawing with pressurized air within the holes. This led to fibers of record porosity (86% air). The measurement of these porous fibers began with a collaboration with a group from the university of Sherbrooke. At the time, the only available detector was a frequency integrating liquid-helium-cooled bolometer (powermeter). A novel directional coupler method for measuring the losses of subwavelength fibers was developed whereby an evanescent coupler is formed by bringing a probe fiber in proximity to the sample fiber
Institute of Scientific and Technical Information of China (English)
尹峰; 王晓东; 梁炜; 任龙韬
2016-01-01
BACKGROUND:The finite element analysis method is more accurate and fast to construct the three-dimensional model of the human skeleton and design the bone surgical medical instrument. OBJECTIVE:To establish locking plate model according to the clavicle model, analyze and evaluate stress distribution of locking plate of the finite element model under bending and torsion conditions. METHODS:Chest scan was carried out in a healthy young adult male by adopting 64-row spiral CT and his two-dimensional image data were gotten. The obtained data were analyzed with Mimics 10.0 software to establish the three-dimensional clavicle finite element model. The clavicle locking fixation plate model was established by applying the UG software. The locking fixation plate was evaluated by utilizing the abaqus software when the plate was bent while down to give force of 200 N, and twisted while 200 N•mm, to simulate the force and analyze the stress distribution of the locking plate. RESULTS AND CONCLUSION:Based on the original image parameters provided by CT, this experiment produced a three-dimensional model of the clavical titanium plate which fitted better to bones. This model can obtain a single individual, personalized plate by three-dimensional printing technology. The finite element analysis basical y can simulate the actual stress of the plate. For straight plate and“S”-shape plate, in lateral bending and axial torsion loads, the maximum stress distribution of the seven-hole titanium plate is located in the center of the center hole. During actual surgical procedures, clavicle fracture fragments and middle locking hole had stress superposition. If the titanium plate can avoid the stress concentration, it can effectively avoid the occurrence of the broken plate after implantation, provide theoretical guidance for clinical practice, and provide reference and technical route for biomechanical analysis of other types of titanium plate.%背景：应用有限元分析的方
Direct imaging of rf waveguide modes via ultra-high field NMR
Tonyushkin, A; Van de Moortele, P -F; Adriany, G; Kiruluta, A
2016-01-01
We demonstrate an experimental method for direct 2D and 3D imaging of magnetic rf field distribution in metal waveguides based on traveling wave (TW) nuclear-magnetic resonance (NMR) imaging at ultra-high field (>7T). The typical apparatus would include an ultra-high field whole body or small bore NMR scanner, waveguide elements filled with NMR active dielectrics with predefined electric and magnetic properties, and TW rf transmit-receive probes. We validated the technique by obtaining TW magnetic-resonance (MR) images of the magnetic field distribution of the rf modes of circular waveguide filled with deionized water in a 16.4 T small-bore NMR scanner and compared the MR images with numerical simulations. Our NMR technique opens up a practical way of imaging of previously inaccessible rf field distribution of modes inside of various shapes metal waveguides with inserted dielectric objects, including waveguide mode converters and transformers.
Multiple temperature sensors embedded in an ultrasonic “spiral-like” waveguide
Directory of Open Access Journals (Sweden)
Suresh Periyannan
2017-03-01
Full Text Available This paper studies the propagation of ultrasound in spiral waveguides, towards distributed temperature measurements on a plane. Finite Element (FE approach was used for understanding the velocity behaviour and consequently designing the spiral waveguide. Temperature measurements were experimentally carried out on planar surface inside a hot chamber. Transduction was performed using a piezo-electric crystal that is attached to one end of the waveguide. Lower order axisymmetric guided ultrasonic modes L(0,1 and T(0,1 were employed. Notches were introduced along the waveguide to obtain ultrasonic wave reflections. Time of fight (TOF differences between the pre-defined reflectors (notches located on the waveguides were used to infer local temperatures. The ultrasonic temperature measurements were compared with commercially available thermocouples.
Okhrimchuk, Andrey; Mezentsev, Vladimir; Shestakov, Alexander; Bennion, Ian
2012-02-13
A depressed cladding waveguide with record low loss of 0.12 dB/cm is inscribed in YAG:Nd(0.3at.%) crystal by femtosecond laser pulses with an elliptical beam waist. The waveguide is formed by a set of parallel tracks which constitute the depressed cladding. It is a key element for compact and efficient CW waveguide laser operating at 1064 nm and pumped by a multimode laser diode. Special attention is paid to mechanical stress resulting from the inscription process. Numerical calculation of mode distribution and propagation loss with the elasto-optical effect taken into account leads to the conclusion that the depressed cladding is a dominating factor in waveguide mode formation, while the mechanical stress only slightly distorts waveguide modes.
Resonant-state expansion of light propagation in non-uniform waveguides
Lobanov, S V; Langbein, W; Muljarov, E A
2016-01-01
A new rigorous approach for precise and efficient calculation of light propagation along non-uniform waveguides is presented. Resonant states of a uniform waveguide, which satisfy outgoing-wave boundary conditions, form a natural basis for expansion of the local electromagnetic field. Using such an expansion at fixed frequency, we convert the light propagation along a non-uniform waveguide into an ordinary second-order matrix differential equation for the expansion coefficients along the waveguide. We illustrate the method on examples of planar waveguides with rectangular holes and evaluate its efficiency compared to the aperiodic Fourier modal method and the finite element method, showing improvements of one to two orders of magnitude. A similar improvement can be expected also for applications in other fields of physics showing wave phenomena, such as acoustics and quantum mechanics.
Oline, L.; Medaglia, J.
1972-01-01
The dynamic finite element method was used to investigate elastic stress waves in a plate. Strain displacement and stress strain relations are discussed along with the stiffness and mass matrix. The results of studying point load, and distributed load over small, intermediate, and large radii are reported. The derivation of finite element matrices, and the derivation of lumped and consistent matrices for one dimensional problems with Laplace transfer solutions are included. The computer program JMMSPALL is also included.
Mode Conversion Behavior of Guided Wave in a Pipe Inspection System Based on a Long Waveguide.
Sun, Feiran; Sun, Zhenguo; Chen, Qiang; Murayama, Riichi; Nishino, Hideo
2016-10-19
To make clear the mode conversion behavior of S0-mode lamb wave and SH0-plate wave converting to the longitudinal mode guided wave and torsional mode guided wave in a pipe, respectively, the experiments were performed based on a previous built pipe inspection system. The pipe was wound with an L-shaped plate or a T-shaped plate as the waveguide, and the S0-wave and SH0-wave were excited separately in the waveguide. To carry out the objective, a meander-line coil electromagnetic acoustic transducer (EMAT) for S0-wave and a periodic permanent magnet (PPM) EMAT for SH0-wave were developed and optimized. Then, several comparison experiments were conducted to compare the efficiency of mode conversion. Experimental results showed that the T(0,1) mode, L(0,1) mode, and L(0,2) mode guided waves can be successfully detected when converted from the S0-wave or SH0-wave with different shaped waveguides. It can also be inferred that the S0-wave has a better ability to convert to the T(0,1) mode, while the SH0-wave is easier to convert to the L(0,1) mode and L(0,2) mode, and the L-shaped waveguide has a better efficiency than T-shaped waveguide.
Mode Conversion Behavior of Guided Wave in a Pipe Inspection System Based on a Long Waveguide
Directory of Open Access Journals (Sweden)
Feiran Sun
2016-10-01
Full Text Available To make clear the mode conversion behavior of S0-mode lamb wave and SH0-plate wave converting to the longitudinal mode guided wave and torsional mode guided wave in a pipe, respectively, the experiments were performed based on a previous built pipe inspection system. The pipe was wound with an L-shaped plate or a T-shaped plate as the waveguide, and the S0-wave and SH0-wave were excited separately in the waveguide. To carry out the objective, a meander-line coil electromagnetic acoustic transducer (EMAT for S0-wave and a periodic permanent magnet (PPM EMAT for SH0-wave were developed and optimized. Then, several comparison experiments were conducted to compare the efficiency of mode conversion. Experimental results showed that the T(0,1 mode, L(0,1 mode, and L(0,2 mode guided waves can be successfully detected when converted from the S0-wave or SH0-wave with different shaped waveguides. It can also be inferred that the S0-wave has a better ability to convert to the T(0,1 mode, while the SH0-wave is easier to convert to the L(0,1 mode and L(0,2 mode, and the L-shaped waveguide has a better efficiency than T-shaped waveguide.
Direct Machining of Low-Loss THz Waveguide Components With an RF Choke.
Lewis, Samantha M; Nanni, Emilio A; Temkin, Richard J
2014-12-01
We present results for the successful fabrication of low-loss THz metallic waveguide components using direct machining with a CNC end mill. The approach uses a split-block machining process with the addition of an RF choke running parallel to the waveguide. The choke greatly reduces coupling to the parasitic mode of the parallel-plate waveguide produced by the split-block. This method has demonstrated loss as low as 0.2 dB/cm at 280 GHz for a copper WR-3 waveguide. It has also been used in the fabrication of 3 and 10 dB directional couplers in brass, demonstrating excellent agreement with design simulations from 240-260 GHz. The method may be adapted to structures with features on the order of 200 μm.
Mulder, C L; Reusswig, P D; Velázquez, A M; Kim, H; Rotschild, C; Baldo, M A
2010-04-26
Luminescent solar concentrators (LSCs) use dye molecules embedded in a flat-plate waveguide to absorb solar radiation. Ideally, the dyes re-emit the absorbed light into waveguide modes that are coupled to solar cells. But some photons are always lost, re-emitted through the face of the LSC and coupled out of the waveguide. In this work, we improve the fundamental efficiency limit of an LSC by controlling the orientation of dye molecules using a liquid crystalline host. First, we present a theoretical model for the waveguide trapping efficiency as a function of dipole orientation. Next, we demonstrate an increase in the trapping efficiency from 66% for LSCs with no dye alignment to 81% for a LSC with vertical dye alignment. Finally, we show that the enhanced trapping efficiency is preserved for geometric gains up to 30, and demonstrate that an external diffuser can alleviate weak absorption in LSCs with vertically-aligned dyes.
Design of non-reciprocal acoustic waveguides by indirect interband transitions
Ishikawa, Atsushi; Tsuruta, Kenji
2017-07-01
We numerically demonstrate a non-reciprocal acoustic waveguide by utilizing the indirect interband transition between two guided modes. The waveguide, consisting of a water core sandwiched between parallel steel plates, is designed to support symmetric and asymmetric guided modes with different frequencies and wavevectors. Dynamic mode conversion is then achieved by applying spatio-temporal density modulation in the core of the waveguide to induce both frequency and wavevector shifts of the incident guided wave. Numerical simulations prove that the phase matching condition is satisfied only for the forward propagation, not for the backward one, thus realizing the non-reciprocal acoustic waveguide. Our approach based on a linear dynamic system may achieve wide-band tunable operation with a low-energy consumption, paving the way toward the sophisticated acoustic diode applications.
Topologically protected photonic transport in bi-anisotropic meta-waveguides
Ma, Tzuhsuan; Mousavi, S Hossein; Shvets, Gennady
2014-01-01
We propose a design of two-dimensional bi-anisotropic meta-waveguide exhibiting topologically nontrivial photonic phase and robust photonic transport. The structure proposed represents a waveguide formed by a periodic array of metallic cylinders placed inside parallel metal plates and is designed to support two pairs of Dirac cones thus allowing emulation of the spin of the electrons in condensed matter systems. It is shown, that by making the meta-waveguide bi-anisotropic one can mimic the spin-orbital interaction in topological insulators and open a complete photonic topological band gap. First-principle numerical simulations demonstrate that the domain walls between two meta-waveguides with reversed bi-anisotropy support photonic edge states robust against certain classes of structural imperfections, including sharp bends and disorder.
DEFF Research Database (Denmark)
Rindorf, Lars Henning; Glückstad, Jesper
2013-01-01
light wavelength while admitting other wavelengths of light which address certain functionalities, e.g. drug release, in the WOW. In particular, we study a bow-tie optical nano-antenna to circular dielectric waveguides in aqueous environments. It is shown with finite element computer simulations......In the current work we intend to use the optical nano-antenna to include various functionalities for the recently demonstrated waveguided optical waveguide (WOW) by Palima et al. (Optics Express 2012). Specifically, we intend to study a WOW with an optical nano-antenna which can block the guiding...... that the nanoantenna can be made to operate in a bandstop mode around its resonant wavelength where there is a very high evanescent strong electrical probing field close to the antennas, and additionally the fluorescence or Raman excitations will be be unpolluted by stray light from the WOW due to the band...
Grating-Coupled Waveguide Cloaking
Institute of Scientific and Technical Information of China (English)
WANG Jia-Fu; QU Shao-Bo; XU Zhuo; MA Hua; WANG Cong-Min; XIA Song; WANG Xin-Hua; ZHOU Hang
2012-01-01
Based on the concept of a grating-coupled waveguide (GCW),a new strategy for realizing EM cloaking is presented.Using metallic grating,incident waves are firstly coupled into the effective waveguide and then decoupled into free space behind,enabling EM waves to pass around the obstacle.Phase compensation in the waveguide keeps the wave-front shape behind the obstacle unchanged.Circular,rectangular and triangular cloaks are presented to verify the robustness of the GCW cloaking.Electric field animations and radar cross section (RCS)comparisons convincingly demonstrate the cloaking effect.
Hollow waveguide for urology treatment
Jelínková, H.; Němec, M.; Koranda, P.; Pokorný, J.; Kőhler, O.; Drlík, P.; Miyagi, M.; Iwai, K.; Matsuura, Y.
2010-02-01
The aim of our work was the application of the special sealed hollow waveguide system for the urology treatment - In our experimental study we have compared the effects of Ho:YAG (wavelength 2100 nm) and Er:YAG (wavelength 2940 nm) laser radiation both on human urinary stones (or compressed plaster samples which serve as a model) fragmentation and soft ureter tissue incision in vitro. Cyclic Olefin Polymer - coated silver (COP/Ag) hollow glass waveguides with inner and outer diameters 700 and 850 μm, respectively, were used for the experiment. To prevent any liquid to diminish and stop the transmission, the waveguide termination was utilized.
Energy Technology Data Exchange (ETDEWEB)
Umbehaun, Pedro Ernesto; Torres, Walmir Maximo; Andrade, Delvonei Alves de [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)]. E-mail: umbehaun@ipen.br; wmtorres@ipen.br; delvonei@ipen.br
2004-07-01
This work presents the thermal-hydraulic analysis for the outermost fuel plates for 5 MW reactor operation power, considering internal flow distribution experimentally measured, and by using the flow through the channels between two fuel elements, external flow. Results showed the necessity of changing the fuel element design, which was taken into account through the reduction of uranium concentration for external plates in order to guarantee its suitable cooling.
Institute of Scientific and Technical Information of China (English)
徐春铃; 王鑫伟
2011-01-01
众所周知Lamb波在复合材料中的传播呈各向异性的特点,经典有限元法模拟这类问题效率不高,所以,本文采用谱有限无法进行研究.先建立了一种新的谱有限板单元,该单元以Gauss-Lobatto-Legendre点作为节点,使质量矩阵足对角矩阵;另外,该单元采用了扩展的位移场,能够较好地模拟板结构的三维特性.然后,对复合材料板结构中Lamb波在对称模式与反对称模式下的传播速度进行了求解,将计算结果与Mindlin板谱单元的结果以及三维弹性理论的结果进行了比较,并讨论了Lamb波在反对称层合板中的传播特点.最后,模拟了Lamb波在含和不含损伤复合材料层合板中的传播,数值结果表明所建立的谱有限板单元可以较好地模拟出Lamb波在复合材料板结构中的传播特性.%It is well known that the propagation of Lamb waves in composite materials exhibits anisotropic characteristics, and that the conventional finite element method is inefficient for modeling such problems.Therefore, the spectral finite element method was used in the present investigations. A new spectral plate element was established. The Gauss-Lobatto-Legendre points were taken as the nodes,thus the mass matrix was in diagonal form. The extended form of the displacement fields was employed, thus the two dimensional element can be used to model three dimensional behavior of plate structures. The velocity of symmetric and anti-symmetric modes of Lamb wave propagating in composite plates was then computed.The results were compared to the data obtained by spectral finite element method based on Mindlin's theory and analytical solutions of three dimensional elasticity. In addition, the characteristics of Lamb wave propagating in anti-symmetric laminated plates were discussed. Finally, Lamb wave propagating in composite laminated plates with and without damage was simulated. Numerical results indicate that the proposed spectral element can be
Fiber-to-Waveguide and 3D Chip-to-Chip Light Coupling Based on Bent Metal-Clad Waveguides
Lu, Zhaolin; Shi, Kaifeng
2016-01-01
Efficient fiber-to-waveguide light coupling has been a key issue in integrated photonics for many years. The main challenge lies in the huge mode mismatch between an optical fiber and a single mode waveguide. Herein, we present a novel fiber-to-waveguide coupler, named "L-coupler", through which the light fed from the top of a chip can bend 90{\\deg} with low reflection and is then efficiently coupled into an on-chip Si waveguide within a short propagation distance (<20{\\mu}m). The key element is a bent metal-clad waveguide with a big matched input port. According to our finite-difference time-domain (FDTD) simulation, the coupling efficiency is over 80% within a broad range of working wavelengths in the near-infrared regime for a transverse electric input Gaussian wave. The coupler is polarization-dependent, with very low coupling efficiency (6%-9%) for transverse magnetic waves. The coupler can also be used for three-dimensional (3D) chip-to-chip optical interconnection by efficiently coupling light into ...
Apetrei, Alin Marian; Minot, Christophe; Moison, Jean-Marie; Belabas, Nadia; Tascu, Sorin
2016-01-01
Knowing the dispersion regime (normal vs anomalous) is important for both an isolated waveguide and a waveguide array. We investigate by the Finite Element Method the dispersion properties of a LiNbO3 waveguides array using two techniques. The first one assumes the Coupled Mode Theory in a 2-waveguide system. The other one uses the actual diffraction curve determined in a 7-waveguide system. In both approaches we find that by decreasing the array period, one passes from normal dispersion by achromatic point to anomalous array dispersion. We then illustrate the wavelength separation by doing Runge-Kutta light propagation simulations in waveguide array. As all the parameters values are technologically feasible, this opens new possibilities for optical data processing.
Surface transport and stable trapping of particles and cells by an optical waveguide loop.
Hellesø, Olav Gaute; Løvhaugen, Pål; Subramanian, Ananth Z; Wilkinson, James S; Ahluwalia, Balpreet Singh
2012-09-21
Waveguide trapping has emerged as a useful technique for parallel and planar transport of particles and biological cells and can be integrated with lab-on-a-chip applications. However, particles trapped on waveguides are continuously propelled forward along the surface of the waveguide. This limits the practical usability of the waveguide trapping technique with other functions (e.g. analysis, imaging) that require particles to be stationary during diagnosis. In this paper, an optical waveguide loop with an intentional gap at the centre is proposed to hold propelled particles and cells. The waveguide acts as a conveyor belt to transport and deliver the particles/cells towards the gap. At the gap, the diverging light fields hold the particles at a fixed position. The proposed waveguide design is numerically studied and experimentally implemented. The optical forces on the particle at the gap are calculated using the finite element method. Experimentally, the method is used to transport and trap micro-particles and red blood cells at the gap with varying separations. The waveguides are only 180 nm thick and thus could be integrated with other functions on the chip, e.g. microfluidics or optical detection, to make an on-chip system for single cell analysis and to study the interaction between cells.
Complete power concentration into a single waveguide in large-scale waveguide array lenses.
Catrysse, Peter B; Liu, Victor; Fan, Shanhui
2014-10-16
Waveguide array lenses are waveguide arrays that focus light incident on all waveguides at the input side into a small number of waveguides at the output side. Ideal waveguide array lenses provide complete (100%) power concentration of incident light into a single waveguide. While of great interest for several applications, ideal waveguide array lenses have not been demonstrated for practical arrays with large numbers of waveguides. The only waveguide arrays that have sufficient degrees of freedom to allow for the design of an ideal waveguide array lens are those where both the propagation constants of the individual waveguides and the coupling constants between the waveguides vary as a function of space. Here, we use state-of-the-art numerical methods to demonstrate complete power transfer into a single waveguide for waveguide array lenses with large numbers of waveguides. We verify this capability for more than a thousand waveguides using a spatial coupled mode theory. We hereby extend the state-of-art by more than two orders of magnitude. We also demonstrate for the first time a physical design for an ideal waveguide array lens. The design is based on an aperiodic metallic waveguide array and focuses ~100% of the incident light into a deep-subwavelength focal spot.
Diamond nanobeam waveguide optomechanics
Khanaliloo, Behzad; Hryciw, Aaron C; Lake, David P; Kaviani, Hamidreza; Barclay, Paul E
2015-01-01
Optomechanical devices sensitively transduce and actuate motion of nanomechanical structures using light, and are central to many recent fundamental studies and technological advances. Single--crystal diamond promises to improve the performance of optomechanical devices, while also providing opportunities to interface nanomechanics with diamond color center spins and related quantum technologies. Here we demonstrate measurement of diamond nanobeam resonators with a sensitivity of 9.5 fm/Hz^0.5 and bandwidth >120 nm through dissipative waveguide--optomechanical coupling. Nanobeams are fabricated from bulk single--crystal diamond using a scalable quasi--isotropic oxygen plasma undercut etching process, and support mechanical resonances with quality factor of 2.5 x 10^5 at room temperature, and 7.2 x 10^5 in cryogenic conditions (5K). Mechanical self--oscillations, resulting from interplay between optomechanical coupling and the photothermal response of nanobeams in a buckled state, are observed with amplitude e...
Snyder, Allan W
1983-01-01
This text is intended to provide an in-depth, self-contained, treatment of optical waveguide theory. We have attempted to emphasize the underlying physical processes, stressing conceptual aspects, and have developed the mathematical analysis to parallel the physical intuition. We also provide comprehensive supplementary sections both to augment any deficiencies in mathematical background and to provide a self-consistent and rigorous mathematical approach. To assist in. understanding, each chapter con centrates principally on a single idea and is therefore comparatively short. Furthermore, over 150 problems with complete solutions are given to demonstrate applications of the theory. Accordingly, through simplicity of approach and numerous examples, this book is accessible to undergraduates. Many fundamental topics are presented here for the first time, but, more importantly, the material is brought together to give a unified treatment of basic ideas using the simplest approach possible. To achieve such a goa...
Slow Light in Metamaterial Waveguides
Lavoie, Benjamin R
2013-01-01
Metamaterials, which are materials engineered to possess novel optical properties, have been increasingly studied. The ability to fabricate metamaterials has sparked an interest in determining possible applications. We investigate using a metamaterial for boundary engineering in waveguides. A metamaterial-clad cylindrical waveguide is used to provide confinement for an optical signal, thereby increasing the local electromagnetic energy density. We show that metamaterial-clad waveguides have unique optical properties, including new modes, which we call hybrid modes. These modes have properties of both ordinary guided modes and surface plasmon-polariton modes. We show that for certain metamaterial parameters, the surface plasmon-polariton modes of a metamaterial-clad waveguide have less propagation loss than those of a metal-clad guide with the same permittivity. This low-loss mode is exploited for all-optical control of weak fields. Embedding three-level {\\Lambda} atoms in the dielectric core of a metamaterial...
Quantum mechanical description of waveguides
Institute of Scientific and Technical Information of China (English)
Wang Zhi-Yong; Xiong Cai-Dong; He Bing
2008-01-01
Applying the spinor representation of the electromagnetic field,this paper present a quantum-mechanical description of waveguides.As an example of application,a potential qubit generated by photon tunnelling is discussed.
Smart, Katie A.; Tappe, Sebastian; Stern, Richard A.; Webb, Susan J.; Ashwal, Lewis D.
2016-03-01
Plate tectonics plays a vital role in the evolution of our planet. Geochemical analysis of Earth’s oldest continental crust suggests that subduction may have begun episodically about 3.8 to 3.2 billion years ago, during the early Archaean or perhaps more than 3.8 billion years ago, during the Hadean. Yet, mantle rocks record evidence for modern-style plate tectonics beginning only in the late Archaean, about 3 billion years ago. Here we analyse the nitrogen abundance, as well as the nitrogen and carbon isotopic signatures of Archaean placer diamonds from the Kaapvaal craton, South Africa, which formed in the upper mantle 3.1 to 3.5 billion years ago. We find that the diamonds have enriched nitrogen contents and isotopic compositions compared with typical mantle values. This nitrogen geochemical fingerprint could have been caused by contamination of the mantle by nitrogen-rich Archaean sediments. Furthermore, the carbon isotopic signature suggests that the diamonds formed by reduction of an oxidized fluid or melt. Assuming that the Archaean mantle was more reduced than the modern mantle, we argue that the oxidized components were introduced to the mantle by crustal recycling at subduction zones. We conclude, on the basis of evidence from mantle-derived diamonds, that modern-style plate tectonics operated as early as 3.5 billion years ago.
Perfect imaging with geodesic waveguides
Miñano, Juan C.; Benítez, Pablo; González, Juan C.
2010-12-01
Transformation optics is used to prove that a spherical waveguide filled with an isotropic material with radial refractive index n=1/r has radially polarized modes (i.e. the electric field is only radial) with the same perfect focusing properties as the Maxwell fish-eye (MFE) lens. An approximate version of that device, comprising a thin waveguide with a homogeneous core, paves the way to experimentally attaining perfect imaging in the MFE lens.
Multiscaffold DNA Origami Nanoparticle Waveguides
2013-01-01
DNA origami templated self-assembly has shown its potential in creating rationally designed nanophotonic devices in a parallel and repeatable manner. In this investigation, we employ a multiscaffold DNA origami approach to fabricate linear waveguides of 10 nm diameter gold nanoparticles. This approach provides independent control over nanoparticle separation and spatial arrangement. The waveguides were characterized using atomic force microscopy and far-field polarization spectroscopy. This work provides a path toward large-scale plasmonic circuitry. PMID:23841957
Mehrkash, Milad; Azhari, Mojtaba; Mirdamadi, Hamid Reza
2014-01-01
The importance of elastic wave propagation problem in plates arises from the application of ultrasonic elastic waves in non-destructive evaluation of plate-like structures. However, precise study and analysis of acoustic guided waves especially in non-homogeneous waveguides such as functionally graded plates are so complicated that exact elastodynamic methods are rarely employed in practical applications. Thus, the simple approximate plate theories have attracted much interest for the calculation of wave fields in FGM plates. Therefore, in the current research, the classical plate theory (CPT), first-order shear deformation theory (FSDT) and third-order shear deformation theory (TSDT) are used to obtain the transient responses of flexural waves in FGM plates subjected to transverse impulsive loadings. Moreover, comparing the results with those based on a well recognized hybrid numerical method (HNM), we examine the accuracy of the plate theories for several plates of various thicknesses under excitations of different frequencies. The material properties of the plate are assumed to vary across the plate thickness according to a simple power-law distribution in terms of volume fractions of constituents. In all analyses, spatial Fourier transform together with modal analysis are applied to compute displacement responses of the plates. A comparison of the results demonstrates the reliability ranges of the approximate plate theories for elastic wave propagation analysis in FGM plates. Furthermore, based on various examples, it is shown that whenever the plate theories are used within the appropriate ranges of plate thickness and frequency content, solution process in wave number-time domain based on modal analysis approach is not only sufficient but also efficient for finding the transient waveforms in FGM plates.
Commissioning of inline ECE system within waveguide based ECRH transmission systems on ASDEX upgrade
DEFF Research Database (Denmark)
Bongers, W. A.; Kasparek, W.; Doelman, N.;
2012-01-01
with dielectric plate beam splitters [2, 3] employed as corrugated oversized waveguide filter, and a resonant Fast Directional Switch, FADIS [4, 5, 6, 7] as ECE/ECCD separation system. This paper presents an overview of the system, the low power characterisation tests and first high power commissioning on AUG....
Institute of Scientific and Technical Information of China (English)
贾富国; 姚丽娜; 韩燕龙; 王会; 史宇菲; 曾勇; 蒋龙伟
2016-01-01
Humidifying evenly is the key to moisture conditioning technology. The uniformity of moisture content depends on the material distribution uniformity. Material uniform plate is the chief work part for increasing the material uniformity, and it has an immediate influence on the follow-up material processing quality and production efficiency. In order to improve the humidifying uniformity in the process of brown rice moisture conditioning, a new type of plate called curved-surface material uniform plate was designed on the basis of existing technology. Combined with the material movement rule on the cone material uniform plate, the parabola was set as the curved generatrix of curved-surface material uniform plate. One of the characteristics of the curved-surface material uniform plate was that it enhanced the uniformity of the material thickness by controlling the floating velocity of the material and offered a favorable condition for uniform humidification of brown rice, and moreover it couldn’t damage brown rice. In this study, on the basis of the theoretical analysis, the working process of the curved-surface material uniform plate was simulated with the discrete element method (DEM), and it was found that the structure parameters and operating conditions of curved-surface refining plate were the key factors affecting its wok performance through the analysis based on the orthogonal design. DEM is a numerical method used for modelling the mechanical behavior of granular materials. Using the EDEM software, the influence laws of the rotation rate of material uniform plate, the curved-surface form and the feeding rateon the material thickness uniformity were simulated and analyzed. According to the performance evaluation indices of evenly distributing material, the structure of curved-surface material uniform plate was optimized. By the response surface analysis method, the mathematical model between each factor and coefficient of variation was established. The
Attenuation in Superconducting Circular Waveguides
Directory of Open Access Journals (Sweden)
K. H. Yeap
2016-09-01
Full Text Available We present an analysis on wave propagation in superconducting circular waveguides. In order to account for the presence of quasiparticles in the intragap states of a superconductor, we employ the characteristic equation derived from the extended Mattis-Bardeen theory to compute the values of the complex conductivity. To calculate the attenuation in a circular waveguide, the tangential fields at the boundary of the wall are first matched with the electrical properties (which includes the complex conductivity of the wall material. The matching of fields with the electrical properties results in a set of transcendental equations which is able to accurately describe the propagation constant of the fields. Our results show that although the attenuation in the superconducting waveguide above cutoff (but below the gap frequency is finite, it is considerably lower than that in a normal waveguide. Above the gap frequency, however, the attenuation in the superconducting waveguide increases sharply. The attenuation eventually surpasses that in a normal waveguide. As frequency increases above the gap frequency, Cooper pairs break into quasiparticles. Hence, we attribute the sharp rise in attenuation to the increase in random collision of the quasiparticles with the lattice structure.
Waveguiding and bending modes in a plasma photonic crystal bandgap device
Directory of Open Access Journals (Sweden)
B. Wang
2016-06-01
Full Text Available Waveguiding and bending modes are investigated in a fully tunable plasma photonic crystal. The plasma device actively controls the propagation of free space electromagnetic waves in the S to X band of the microwave spectrum. An array of discharge plasma tubes form a square crystal lattice exhibiting a well-defined bandgap, with individual active switching of the plasma elements to allow for waveguiding and bending modes to be generated dynamically. We show, through simulations and experiments, the existence of transverse electric (TE mode waveguiding and bending modes.
Effect of deformation and dielectric ﬁlling on electromagnetic propagation through waveguides
Indian Academy of Sciences (India)
Ajay Chaudhari
2003-12-01
The effect of depression and protrusion of vertical walls and dielectric ﬁlling on electromagnetic propagation through -band rectangular waveguides is studied using the ﬁnite element method. The effect of these deformations and dielectric ﬁlling on TE10, TE20 mode cutoff frequencies and passband is studied. The results are compared with those of -band rectangular waveguides with depression and protrusion with air medium. TE10, TE20 mode cutoff frequencies for waveguides with depression and protrusion and ﬁlled with dielectric medium are less than that for air medium. However, the bandwidth in some cases of dielectric medium is larger than that for air medium.
Finite element analysis of the free-damped beam-stiffened plate%壳梁组合结构自由阻尼处理有限元分析
Institute of Scientific and Technical Information of China (English)
杨莉; 孙庆鸿; 朱壮瑞; 许志华
2004-01-01
A finite element model is presented for free-damped beam-stiffened plates. The nodes of the plate elements are treated as master-nodes, and the corresponding nodes of the beam elements are considered as slave-nodes. The stiffness and mass matrices of the elements are developed. Based on the analysis of the dynamic properties of the structures, modal loss factors are predicted by the modal strain energy method. Finally, an example is given to compare the results obtained from the proposed method with the results of the ANSYS software. The results show that the method in this paper is computationally efficient, simple and feasible with high precision and engineering practicability.%构造了壳梁组合结构自由阻尼处理薄板结构的有限元模型, 将板单元的节点作为主节点, 梁单元的节点作为从属节点, 推导出相应的刚度矩阵和质量矩阵. 在用有限元法进行结构动态特性分析的基础上, 用模态变形能法估算了结构的模态损耗因子. 最后以一计算实例将本文方法所得结果与用ANSYS软件计算所得结果进行了比较, 结果表明本文方法计算效率高、简单可行, 且具有较高的精度和工程实用性.
Layer-guided shear acoustic plate mode sensor
2003-01-01
Experimental data are presented for an acoustic wave sensor based on a layer-guided shear acoustic plate mode excited on a thin quartz substrate. The effect of coating the front and back faces with polymer waveguiding layers is shown to convert the plate modes into layer-guided plate modes in a manner analogous to Love waves and to produce a similar enhancement of mass sensitivity. These layer-guided plate mode devices offer the possibility of liquid-phase sensing with transducers situated on...
Graphene-based waveguide resonators for submillimeter-wave applications
Ilić, Andjelija Ž.; Bukvić, Branko; Ilić, Milan M.; Budimir, Djuradj
2016-08-01
Utilization of graphene covered waveguide inserts to form tunable waveguide resonators is theoretically explained and rigorously investigated by means of full-wave numerical electromagnetic simulations. Instead of using graphene-based switching elements, the concept we propose incorporates graphene sheets as parts of a resonator. Electrostatic tuning of the graphene surface conductivity leads to changes in the electromagnetic field boundary conditions at the resonator edges and surfaces, thus producing an effect similar to varying the electrical length of a resonator. The presented outline of the theoretical background serves to give phenomenological insight into the resonator behavior, but it can also be used to develop customized software tools for design and optimization of graphene-based resonators and filters. Due to the linear dependence of the imaginary part of the graphene surface impedance on frequency, the proposed concept was expected to become effective for frequencies above 100 GHz, which is confirmed by the numerical simulations. A frequency range from 100 GHz up to 1100 GHz, where the rectangular waveguides are used, is considered. Simple, all-graphene-based resonators are analyzed first, to assess the achievable tunability and to check the performance throughout the considered frequency range. Graphene-metal combined waveguide resonators are proposed in order to preserve the excellent quality factors typical for the type of waveguide discontinuities used. Dependence of resonator properties on key design parameters is studied in detail. Dependence of resonator properties throughout the frequency range of interest is studied using eight different waveguide sections appropriate for different frequency intervals. Proposed resonators are aimed at applications in the submillimeter-wave spectral region, serving as the compact tunable components for the design of bandpass filters and other devices.
Institute of Scientific and Technical Information of China (English)
黄诸侯; 李俊; 杜景文; 陈日齐; 张建新
2013-01-01
背景：有多种钢板治疗跟骨骨折，但究竟哪种效果更好，目前尚无定论。 目的：在跟骨骨折三维有限元模型上模拟加载3种类型的钢板，观察比较应力、应变及移位等生物力学性能。 方法：在踝关节中立位和背伸20°位建立跟骨骨折三维有限元模型，分别模拟使用跟骨Ⅰ型、Ⅱ型、Ⅲ型3种形状钢板对骨折进行固定，加载后计算内固定物自身的应力分布、骨骼的应力分布及骨折块间的移位程度。 结果与结论：①两种体位骨折模型3种固定方式下的钢板应力分布都不均匀，钢板前部应力水平均高于后部，Ⅰ型钢板的应力分布相对比较均匀。②两种体位骨折模型3种固定方式下跟骨的应力最大值均在跟骨前部，而正常跟骨最大应力值在跟结节处，Ⅰ型钢板固定跟骨骨折后骨骼的最大应力值均小于Ⅱ型、Ⅲ型钢板。③两种体位骨折模型3种固定方式下均发生了骨折块间的位移，其位移趋势是一致的。结果显示，与Ⅱ型、Ⅲ型钢板固定相比较，跟骨Ⅰ型钢板固定后所承受应力更小，且应力分布更均匀，较符合生物力学原理。%BACKGROUND:There are many types of plate can be used for the treatment of calcaneus fracture, but it is not clear which type has the best effect. OBJECTIVE:To observe and compare the biomechanical properties, such as stress, strain and displacement of three types of plate through loading them on the three-dimensional finite element model of calcaneus fracture. METHODS:The three-dimensional finite element model of calcaneus fracture was established when the ankle joint was in neutral position and back stretches 20° position, then the type Ⅰ, type Ⅱ and type Ⅲ plates were used to fix the fracture model. Through loading force on the model, the stress distribution of plates and calcaneus, and displacement between fracture gaps were calculated
Vawter, G. Allen
2008-02-26
A self-electrooptic effect device ("SEED") is integrated with waveguide interconnects through the use of vertical directional couplers. Light initially propagating in the interconnect waveguide is vertically coupled to the active waveguide layer of the SEED and, if the SEED is in the transparent state, the light is coupled back to the interconnect waveguide.
Directory of Open Access Journals (Sweden)
Marcin Krzeszowiec
2015-03-01
Full Text Available Computer simulations of physical phenomena are at the moment common both in science and industry. The possibility of finding approximate solutions for complicated systems of differential equations, mathematically describing issues in the fields of mechanics, physics or chemistry, allows for shorten design and research time, often significantly reducing the need for expensive experimental studies or costly production of prototypes. However, the mentioned prevalence of these methods, particularly the Finite Element Method, resulted in analysis outcomes to be often in advance regarded as accurate ones. The purpose of the article is to showcase, on a simple stress analysis problem, how parameters such as the density of the finite element mesh, finite element formulation or integration scheme significantly influence on the simulation results and how easy it is to end up with the results that do not hold any physical sense, despite the fact that all the basic assumptions of correct analysis (suitable boundary conditions, total system energy stored etc. have been met. The results of this study can serve as a warning against premature conclusion drawing from calculations carried out by means of FEM simulation.[b]Keywords[/b]: computational mechanics, finite element method, shell elements, numerical integration
Plate shell structures - statics and stability
DEFF Research Database (Denmark)
Almegaard, Henrik
2008-01-01
This paper describes the basic structural system, statics and spatial stability of plate shells. The structural system can be considered as a single layer of planar elements, where each element only transfers in-plane (membrane) forces to its neighbouring elements. External out-of-plane loads...... are carried into the structure as in-plane forces by plate action in each element. These in-plane forces are then carried through the plate structure to the supports as in-plane forces by membrane action. The consequence is that the spatial stability of the structure can be simply analysed by considering...... the plate system as only subject to in-plane loads. The stability of such systems is based on the fact that each plane element is held fixed in space by three fixed support lines and that these support lines can be provided by three plane neighbour elements. This means that the spatial stability of a plate...
Effects of beryllium coating layer on performance of the ultrasonic waveguide sensor.
Joo, Young-Sang; Bae, Jin-Ho; Kim, Jong-Bum; Kim, Jin-Yeon
2013-02-01
Under-sodium viewing is one of the critical technical issues and requirements for the in-service inspection of the sodium-cooled fast reactor (SFR) that is currently under development. The waveguide sensor that uses leaky A(0) mode Lamb waves has shown its potential for high-resolution viewing/scanning of the reactor core and in-vessel structures. However, a few problems arise under a liquid sodium environment due to high sound speed in liquid sodium and dispersion in the long waveguide plate, which simultaneously deteriorate the reconstructed C-scan images. This paper proposes coating the surface of the waveguide sensor plate with a thin layer of material that has a very high ultrasonic wave velocity. It is shown that this coating layer can largely reduce the size (width) and radiation angle of the acoustic beam from the waveguide sensor. This paper precisely analyzes the effects of coating parameters on the beam quality. The proposed idea is validated through ultrasonic experiments in which the radiation beam profiles and group velocities in waveguide sensors with different surface treatments are measured and compared.
Miniaturized Waveguide Fourier Transform Spectrometer Project
National Aeronautics and Space Administration — To characterize the IR optical properties of the metal-coated hollow waveguide ensemble; configure the Hollow Waveguide FTS (HWFTS) chip in such a way that we...
Writing Waveguide in LN With fs Laser
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
We investigated the waveguide formation in Lithium Niobate with Femtosecond laser pulse writing directly. The output optical field through waveguide has been observed and refractive-index change was characterized by using grating method.
一种算子自定义小波薄板单元及应用%An operator custom-design wavelet-based thin plate element and its application
Institute of Scientific and Technical Information of China (English)
汪友明; 王文庆; 沈建冬; 曹宏瑞
2014-01-01
提出了基于提升方案的自适应算子自定义小波有限元法，构造了一种新的算子自定义小波薄板单元。建立二维 Hermite型有限元多分辨空间和两尺度关系，并由广义变分原理推导薄板结构关于尺度函数和小波函数的内积关系式，即算子。为满足算子正交性，提出基于提升方案的算子自定义小波单元的构造方法，其优点在于可根据问题的需要来设计具有期望特性的小波基。提出基于两尺度误差的自适应算子自定义小波有限元方法，通过向大于误差阈值的局域添加算子自定义小波，实现薄板结构问题的高效求解。算子自定义小波有限元法节省了重新划分网格或提高插值函数的阶次所带来的大量有限元前处理时间，并且实现薄板问题的高效解耦运算。%An adaptive operator custom-design wavelet finite element method based on the lifting scheme is proposed and a new operator custom-design wavelet thin plate element is constructed .A two-dimen-sional Hermite-type multiresolution finite element space and two-level relation are built .The inner pro-duction equation of scaling functions and wavelet functions of thin plate structure ,also called the opera-tor ,is derived based on the general variational principle .The construction method of operator custom-design wavelet finite elements based on the lifting scheme is presented to meet the operator-orthogonal-ization .The property of the method is that the wavelets can be designed with the specified feature depen-ding on the requirements of the problems .An adaptive operator custom-design wavelet finite element method is presented on the two-level error estimation ,which can solve the thin plate problems efficiently by adding operator custom-design wavelets into the local domains higher than the threshold value .The operator custom-design wavelet finite element method saves a great deal of preprocessing time of refining the
Generalized Modal Analysis of Electromagnetic - and Quantum-Waveguide Structures and Discontinuities
Weisshaar, Andreas
Generalized modal analysis techniques for the characterization and modeling of dissipationless planar waveguide structures and discontinuities encountered in microwave and optical integrated circuits, as well as of quantum waveguide structures and devices, are presented. The frequency-dependent transmission properties of the curved microstrip bend are derived by utilizing a second-order perturbation analysis of the equivalent modified curved waveguide model and a mode-matching method which includes the higher order modes. An extension of the mode-matching method for characterization of microstrip right-angle bends and T junctions having a rectangular notch is formulated. The modal solutions for an arbitrary graded-index dielectric slab waveguide are derived by applying the generalized telegraphist's equations to the equivalent inhomogeneous parallel-plate waveguide model with electric or magnetic walls. These modal solutions are employed in a mode-matching procedure to calculate the transmission properties of a step discontinuity in typical diffused optical dielectric slab waveguides. Power loss calculations for an abrupt offset in a diffused optical waveguide show a smooth increase in radiation loss whereas a sharp transition from almost zero to nearly total radiation loss is found for an abrupt change in diffusion depth. In the analysis of quantum waveguide structures, the modal expansions of the wave function together with a mode-matching technique are utilized. The computed generalized scattering matrices (GSMs) of junctions and uniform waveguide sections are combined via an extended GSM technique to obtain the scattering parameters of composite quantum waveguide structures. Results for cascaded right-angle bends and periodic multi-waveguide structures in a split-gate configuration are presented assuming hard wall confinement. For the multisection structures, strong resonant behavior similar to that in resonant tunneling diodes is found. Calculated current
Loop coupled resonator optical waveguides.
Song, Junfeng; Luo, Lian-Wee; Luo, Xianshu; Zhou, Haifeng; Tu, Xiaoguang; Jia, Lianxi; Fang, Qing; Lo, Guo-Qiang
2014-10-06
We propose a novel coupled resonator optical waveguide (CROW) structure that is made up of a waveguide loop. We theoretically investigate the forbidden band and conduction band conditions in an infinite periodic lattice. We also discuss the reflection- and transmission- spectra, group delay in finite periodic structures. Light has a larger group delay at the band edge in a periodic structure. The flat band pass filter and flat-top group delay can be realized in a non-periodic structure. Scattering matrix method is used to calculate the effects of waveguide loss on the optical characteristics of these structures. We also introduce a tunable coupling loop waveguide to compensate for the fabrication variations since the coupling coefficient of the directional coupler in the loop waveguide is a critical factor in determining the characteristics of a loop CROW. The loop CROW structure is suitable for a wide range of applications such as band pass filters, high Q microcavity, and optical buffers and so on.
Initial results for a 170 GHz high power ITER waveguide component test stand
Bigelow, Timothy; Barker, Alan; Dukes, Carl; Killough, Stephen; Kaufman, Michael; White, John; Bell, Gary; Hanson, Greg; Rasmussen, Dave
2014-10-01
A high power microwave test stand is being setup at ORNL to enable prototype testing of 170 GHz cw waveguide components being developed for the ITER ECH system. The ITER ECH system will utilize 63.5 mm diameter evacuated corrugated waveguide and will have 24 >150 m long runs. A 170 GHz 1 MW class gyrotron is being developed by Communications and Power Industries and is nearing completion. A HVDC power supply, water-cooling and control system has been partially tested in preparation for arrival of the gyrotron. The power supply and water-cooling system are being designed to operate for >3600 second pulses to simulate the operating conditions planned for the ITER ECH system. The gyrotron Gaussian beam output has a single mirror for focusing into a 63.5 mm corrugated waveguide in the vertical plane. The output beam and mirror are enclosed in an evacuated duct with absorber for stray radiation. Beam alignment with the waveguide is a critical task so a combination of mirror tilt adjustments and a bellows for offsets will be provided. Analysis of thermal patterns on thin witness plates will provide gyrotron mode purity and waveguide coupling efficiency data. Pre-prototype waveguide components and two dummy loads are available for initial operational testing of the gyrotron. ORNL is managed by UT-Battelle, LLC, for the U.S. Dept. of Energy under Contract DE-AC-05-00OR22725.
Buried ion-exchanged glass waveguides: burial-depth dependence on waveguide width.
Madasamy, P; West, B R; Morrell, M M; Geraghty, D F; Honkanen, S; Peyghambarian, N
2003-07-01
A detailed theoretical and experimental study of the depth dependence of buried ion-exchanged waveguides on waveguide width is reported. Modeling, which includes the effect of nonhomogeneous time-dependent electric field distribution, agrees well with our experiments showing that burial depth increases linearly with waveguide width. These results may be used in the proper design of integrated optical circuits that need waveguides of different widths at different sections, such as arrayed waveguide gratings.
Plate acoustic waves for low frequency delay line delaying signals up to 0.5 ms
Zaitsev, B. D.; Kuznetsova, I. E.; Zemnyukov, N. E.; Proidakov, V. I.; Teplykh, A. A.
2010-01-01
At present time there exists the problem of development of main memory elements based on the delay of electromagnetic signal with frequency of ˜100 kHz on hundreds microseconds. This paper is devoted to theoretical and experimental investigation of the possibility of development of corresponding acoustic delay lines. It was supposed to use the antisymmetric acoustic waves of zero order propagating in thin (compared to wavelength) metal plates. In this connection, we theoretically studied the parameters of A0 waves propagating in plates of various metals such as brass, bronze, copper, steel, and aluminum. For analysis of wave propagation in aforementioned plates, we used the standard motion equation and constitutive material equation for investigated medium as well as corresponding mechanical boundary conditions. As a result, the phase and group velocities versus parameter hf (h= plate thickness, f= wave frequency) were calculated for A0 wave propagating in mentioned above plates. It has been found that for steel plate the delay time about 0.5 ms can be achieved at the lengths of waveguide L=0.373, 0.737, and 0.971 m for h=0.175, 0.5, and 1.0 mm, respectively at f=120 kHz. The theoretical results were verified by experiment, which showed the possibility of development of corresponding delay lines with delay time ˜500 mks and acceptable insertion loss. In experiments, the excitation and reception of A0 waves were performed by the standard piezoelectric transducers of longitudinal waves and prismatic steel concentrators. The details of theoretical analysis and experiment are described.
Plasmonic waveguides cladded by hyperbolic metamaterials
DEFF Research Database (Denmark)
Ishii, Satoshi; Shalaginov, Mikhail Y.; Babicheva, Viktoriia E.
2014-01-01
Strongly anisotropic media with hyperbolic dispersion can be used for claddings of plasmonic waveguides (PWs). In order to analyze the fundamental properties of such waveguides, we analytically study 1D waveguides arranged from a hyperbolic metamaterial (HMM) in a HMM-Insulator-HMM (HIH) structure...
Advancements in X-ray waveguides and their applications in coherent diffraction imaging
Energy Technology Data Exchange (ETDEWEB)
Pelliccia, D. [Institut fuer Synchrotronstrahlung-ANKA Forschungszentrum Karlsruhe Herman-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany)], E-mail: daniele.pelliccia@iss.fzk.de; Bukreeva, I. [Istituto di Fotonica e Nanotecnologie-CNR, Via Cineto Romano 42, 00156 Roma (Italy); Giannini, C.; De Caro, L. [Istituto di Cristallografia-CNR, Via Amendola 122/O, 70126 Bari (Italy); Cedola, A.; Scarinci, F.; Lagomarsino, S. [Istituto di Fotonica e Nanotecnologie-CNR, Via Cineto Romano 42, 00156 Roma (Italy)
2009-10-15
X-ray planar waveguides are currently used tools, in synchrotron radiation facilities, to produce a coherent beam with typical dimensions in the range of tens or hundreds of nanometers. The properties of waveguided beams such as divergence and coherence turns out to be very interesting for several applications both in synchrotron and in laboratory sources. These features will be reviewed in the present paper for different coupling methods of the radiation field with the waveguide channel. Details of fabrication procedures and experimental results concerning front coupling waveguide are reported. The waveguide properties can be estimated from the far-field diffracted beam by a Fourier analysis giving the autocorrelation function of the exit field. Due to the high degree of coherence of the exiting beam, X-ray waveguides can be successfully exploited in coherent diffraction imaging experiments. We review results concerning Fresnel coherent diffraction imaging experiments with hard X-rays, using planar waveguides as optical elements in one and two dimensions.
Fabrication of optical channel waveguides in crystals and glasses using macro- and micro ion beams
Energy Technology Data Exchange (ETDEWEB)
Bányász, I., E-mail: banyasz@sunserv.kfki.hu [Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Rajta, I.; Nagy, G.U.L. [MTA Atomki, Institute for Nuclear Research, Hungarian Academy of Sciences, P.O. Box 51, H-4001 Debrecen (Hungary); Zolnai, Z. [Research Institute for Technical Physics and Materials Science, Research Centre for Natural Sciences, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Havranek, V. [Nuclear Physics Institute AV CR, Řež near Prague 250 68 (Czech Republic); Pelli, S. [MDF-Lab, “Nello Carrara” Institute of Applied Physics, IFAC-CNR, Via Madonna del Piano 10, 50019 Sesto Fiorentino, FI (Italy); “Enrico Fermi” Center for Study and Research, Piazza del Viminale 2, 00184 Roma (Italy); Veres, M. [Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Berneschi, S.; Nunzi-Conti, G. [MDF-Lab, “Nello Carrara” Institute of Applied Physics, IFAC-CNR, Via Madonna del Piano 10, 50019 Sesto Fiorentino, FI (Italy); Righini, G.C. [“Enrico Fermi” Center for Study and Research, Piazza del Viminale 2, 00184 Roma (Italy)
2014-07-15
Active and passive optical waveguides are fundamental elements in modern telecommunications systems. A great number of optical crystals and glasses were identified and are used as good optoelectronic materials. However, fabrication of waveguides in some of those materials remains still a challenging task due to their susceptibility to mechanical or chemical damages during processing. Researches were initiated on ion beam fabrication of optical waveguides in tellurite glasses. Channel waveguides were written in Er:TeO{sub 2}–WO{sub 3} glass through a special silicon mask using 1.5 MeV N{sup +} irradiation. This method was improved by increasing N{sup +} energy to 3.5 MeV to achieve confinement at the 1550 nm wavelength, too. An alternative method, direct writing of the channel waveguides in the tellurite glass using focussed beams of 6–11 MeV C{sup 3+} and C{sup 5+} and 5 MeV N{sup 3+}, has also been developed. Channel waveguides were fabricated in undoped eulytine-(Bi{sub 4}Ge{sub 3}O{sub 12}) and sillenite type (Bi{sub 12}GeO{sub 20}) bismuth germanate crystals using both a special silicon mask and a thick SU8 photoresist mask and 3.5 MeV N{sup +} irradiation. The waveguides were studied by phase contrast and interference microscopy and micro Raman spectroscopy. Guiding properties were checked by the end fire method.
Graphene nano-ribbon waveguides
He, S; He, Y
2013-01-01
Graphene as a one-atom-thick platform for infrared metamaterial plays an important role in optical science and engineering. Here we study the unique properties of some plasmonic waveguides based on graphene nano-ribbon. It is found that a graphene ribbon of finite width leads to the occurrence of coupled edge mode. The single-mode region of a single freestanding graphene ribbon is identified at a fixed frequency of 30 THz. A low-loss waveguide structure, consisting of a graphene layer, a silica buffer layer and silicon substrate is proposed to reduce the propagation loss and obtain a high figure of merit for future integration of waveguide devices. Furthermore, two coupled ribbon configurations, namely, side-side coupling and top-bottom coupling, are investigated. As a device example, a nano-ring cavity of ultra-small size is designed.
Integrated microfluidic spectroscopic sensor using arrayed waveguide grating
Hu, Zhixiong; Glidle, Andrew; Ironside, Charles N.; Sorel, Marc; Strain, Michael; Cooper, Jonathan M.; Yin, Huabing
2013-08-01
With non-invasive properties and high sensitivities, portable optical biosensors are extremely desirable for point-of-care (POC) applications. Lab-on-a-chip technology such as microfluidics has been treated as an ideal approach to integrate complex sample processing and analysis units with optical detection elements. The work in this paper has developed an integrated dispersive component in combination with a microfluidic chip, providing a portable and inexpensive platform for on-chip spectroscopic sensing. We demonstrate an integrated microfluidic spectroscopic sensor by using an arrayed waveguide grating (AWG) device. In particular, a visible AWG device (λc=680nm) with chip size of 12.1mm by 1.5mm was designed and fabricated by employing flamed hydrolysis deposited (FHD) silica as the waveguide material. A straight input waveguide is used to perform device characterization while a perpendicular curved waveguide is employed to introduce laser excitation light. A polymer microfluidic chip is integrated with the AWG device by oxygen plasma bonding. To prove effectiveness of the integrated spectroscopic sensor, fluorescence spectrum of an organic fluorophore (Cy5) was tested. Reconstructed spectrum by using the AWG device is compared with the outcome from a conventional spectrometer and a good consistency is presented.
Commissioning of inline ECE system within waveguide based ECRH transmission systems on ASDEX upgrade
Directory of Open Access Journals (Sweden)
Donné A.J.H.
2012-09-01
Full Text Available A CW capable inline electron cyclotron emission (ECE separation system for feedback control, featuring oversized corrugated waveguides, is commissioned on ASDEX upgrade (AUG. The system is based on a combination of a polarization independent, non-resonant, Mach-Zehnder diplexer equipped with dielectric plate beam splitters [2, 3] employed as corrugated oversized waveguide filter, and a resonant Fast Directional Switch, FADIS [4, 5, 6, 7] as ECE/ECCD separation system. This paper presents an overview of the system, the low power characterisation tests and first high power commissioning on AUG.
TSUNAMI WAVE PROPAGATION ALONG WAVEGUIDES
Directory of Open Access Journals (Sweden)
Andrei G. Marchuk
2009-01-01
Full Text Available This is a study of tsunami wave propagation along the waveguide on a bottom ridge with flat sloping sides, using the wave rays method. During propagation along such waveguide the single tsunami wave transforms into a wave train. The expression for the guiding velocities of the fastest and slowest signals is defined. The tsunami wave behavior above the ocean bottom ridges, which have various model profiles, is investigated numerically with the help of finite difference method. Results of numerical experiments show that the highest waves are detected above a ridge with flat sloping sides. Examples of tsunami propagation along bottom ridges of the Pacific Ocean are presented.
Institute of Scientific and Technical Information of China (English)
艾拜拉·热合曼; 帕提曼·亚森; 帕提曼·尼扎木丁; 阿布力孜·伊米提
2012-01-01
The polyvinyl pyrrolidone ( PVP) doped stearic acid composite film was deposited onto the surface of a single mode potassium ion ( K+) exchanged glass optical waveguide OWG by spin coated method, the OWG sensor was fixed on the gas sensor system to detect VOCs gases. Experimental results showed that,the sensor has high repeatability and selectivity towards lower concentration xylene gas at room temperature, its response time and recovery time was 9 s and 35 s for lx10-6 volume fraction xylene gas, the relative standard deviation(R. S. D)of output light intensity was ±4. 17% at this concentration. The sensor is easily fabricated and had many advantages such as high sensitivity, fast response and recovery speed, good reversibility, low cost.%利用旋转-甩涂法将聚乙烯吡咯烷酮(PVP)-硬脂酸复合薄膜固定在钾离子(K+)交换玻璃光波导表面,研制了PVP-硬脂酸复合薄膜/K+交换玻璃光波导元件,用于对挥发性有机物蒸汽进行检测.实验结果表明,在室温下该元件对低浓度的二甲苯蒸汽仍有较好的重复性和选择性响应,能够检测到1×10-6(体积分数)的二甲苯,其响应和恢复时间分别为9 s和35 s,相对标准偏差为±4.17％.该元件具有灵敏度高、响应-恢复速度快、可逆性好、成本低、容易制作等特点.
Nonlinear waves in waveguides with stratification
Leble, Sergei B
1991-01-01
S.B. Leble's book deals with nonlinear waves and their propagation in metallic and dielectric waveguides and media with stratification. The underlying nonlinear evolution equations (NEEs) are derived giving also their solutions for specific situations. The reader will find new elements to the traditional approach. Various dispersion and relaxation laws for different guides are considered as well as the explicit form of projection operators, NEEs, quasi-solitons and of Darboux transforms. Special points relate to: 1. the development of a universal asymptotic method of deriving NEEs for guide propagation; 2. applications to the cases of stratified liquids, gases, solids and plasmas with various nonlinearities and dispersion laws; 3. connections between the basic problem and soliton- like solutions of the corresponding NEEs; 4. discussion of details of simple solutions in higher- order nonsingular perturbation theory.
Subwavelength line imaging using plasmonic waveguides
Podoliak, Nina; Prangsma, Jord C; Pinkse, Pepijn W H
2015-01-01
We investigate the subwavelength imaging capacity of a two-dimensional fanned-out plasmonic waveguide array, formed by air channels surrounded by gold metal layers for operation at near-infrared wavelengths, via finite element simulations. High resolution is achieved on one side of the device by tapering down the channel width while simultaneously maintaining propagation losses of a few dB. On the other, low-resolution side, output couplers are designed to optimize coupling to free space and to minimize channel cross talk via surface plasmons. Point sources separated by {\\lambda}/15 can still be clearly distinguished. Moreover, up two 90% of the power of a point dipole is coupled to the device. Applications are high-resolution linear detector arrays and, by operating the device in reverse, high-resolution optical writing.
Energy Technology Data Exchange (ETDEWEB)
Rios, Ilka Antonia
2013-09-01
This master thesis presents a study to verify the impact of the uranium concentration reduction in the side plates of the reactor IEA-R1 fuel elements on the neutronic and thermal-hydraulic analyses. To develop such study, a previous IPEN-CNEN/SP research was reproduced by simulating the fuel elements burn-up, with side plate uranium density reduced to 50, 60 and 70% of the standard fuel element plates. This research begins with the neutronic analysis using the computer code HAMMER and the first step consists in the calculation of the cross section of all materials presented at the reactor core, with their initial concentration; the second step consists in the calculation of the fast and thermal neutron group fluxes and power densities for fuel elements using the computer code CITATION. HAMMER output data is used as input data. Once the neutronic analysis is finished and the most critical fuel elements with highest power density have been defined, the thermal-hydraulics analysis begins. This analysis uses MCTR-IEA-R1 thermal-hydraulics model, which equations are solved by commercial code EES. Thermalhydraulics analysis input is the power density data calculated by CITATION: it is considered the highest power density on each fuel element, where there is a higher energy release and, consequently, higher temperatures. This data is used on energy balance equations to calculate temperatures on critical fuel element regions. Reactor operation comparison for three different uranium densities on fuel side plates is presented. Uranium density reduction contributes to the cladding surface temperature to remain below the established limit, as reactor operation safety requirement and it does not affect significantly fuel element final burn-up nor reactor reactivity. The reduction of uranium in the side plates of the fuel elements of the IEA-R1 showed to be a viable option to avoid corrosion problems due to high temperatures. (author)
Institute of Scientific and Technical Information of China (English)
尹辉; 于德介; 陈宁; 夏百战
2015-01-01
为提高板结构-声场耦合分析的计算精度,将有限元-径向点插值法(Finite Element-Radial Point Interpolation,FE-RPIM)推广到板结构-声场耦合问题的结构域分析中,推导了FE-RPIM/FEM法分析板结构-声场耦合问题的计算公式.板结构-声场耦合分析的FE-RPIM/FEM法在流体域中采用标准的有限元插值函数;在结构域中采用有限元-径向点插值法,其形函数由等参单元形函数和径向点插值函数相结合构成,继承了有限元法的单元兼容性和径向点插值法的Kronecker性质,提高了插值精度.以六面体声场-结构耦合模型为研究对象进行分析,结果表明,与板结构-声场耦合问题分析的有限元/有限元法(Finite element method/Finite element method,FEM/FEM) 和光滑有限元/有限元法(Smoothed Finite Element Method/Finite Element Method,SFEM/FEM)相比,FE-RPIM/FEM在分析板结构-声场耦合问题时具有更高的精度.%In order to improve the accuracy of simulation analysis for plate structural-acoustic coupling systems,the finite element-radial point interpolation method (FE-RPIM) was extended to solve the plate structural-acoustic coupling problems and the formulation of coupled FE-RPIM/FEM was presented for the plate structural-acoustic coupled systems.The finite element-radial point interpolation method was used for structure domain and the standard FEM model was used for the acoustic domain.The shape function of the finite element-radial point interpolation method is the combination of the isoparametric element shape function and the radial point interpolation function;the compatibility properties of the finite element method and Kronecker properties of RPIM were inherited.Thus,the accuracy of simulation analysis can be improved.The numerical example of a box structural-acoustic coupled model was presented,which shows that the FE-RPIM/FEM method achieves higher accuracy as compared with FEM/FEM and SFEM/FEM for the analysis of plate
Two-Dimentional Photonic Crystal Waveguides
DEFF Research Database (Denmark)
Søndergaard, Thomas; Dridi, Kim
1999-01-01
possible a novel class of optical microcavities, whereas line defects make possible a novel class of waveguides. In this paper we will analyze two-dimensional photonic crystal waveguides based on photonic crystals with rods arranged on a triangular and a square lattice using a plane-wave expansion method...... and a finite-difference-time-domain (FDTD) method. Design parameters, i.e. dielectric constants, rod diameter and waveguide width, where these waveguides are single-moded and multi-moded will be given. We will also show our recent results regarding the energy-flow (the Poynting vector) in these waveguides...
Quantum Electrodynamics in Photonic Crystal Waveguides
DEFF Research Database (Denmark)
Nielsen, Henri Thyrrestrup
In this thesis we have performed quantum electrodynamics (QED) experiments in photonic crystal (PhC) waveguides and cavity QED in the Anderson localized regime in disordered PhC waveguides. Decay rate measurements of quantum dots embedded in PhC waveguides has been used to map out the variations...... probability. The Q-factor distributions of Anderson localized modes have been measured in PhC waveguides with articial induced disorder with embedded emitters. The largest Q-factors are found in the sample with the smallest amount of disorder. From a comparison with the waveguide model the localization length...
Plasmonic waveguides with hyperbolic multilayer cladding
Babicheva, Viktoriia E; Ishii, Satoshi; Boltasseva, Alexandra; Kildishev, Alexander V
2014-01-01
Engineering plasmonic metamaterials with anisotropic optical dispersion enables us to tailor the properties of metamaterial-based waveguides. We investigate plasmonic waveguides with dielectric cores and multilayer metal-dielectric claddings with hyperbolic dispersion. Without using any homogenization, we calculate the resonant eigenmodes of the finite-width cladding layers, and find agreement with the resonant features in the dispersion of the cladded waveguides. We show that at the resonant widths, the propagating modes of the waveguides are coupled to the cladding eigenmodes and hence, are strongly absorbed. By avoiding the resonant widths in the design of the actual waveguides, the strong absorption can be eliminated.
Baskin, Lev; Plamenevskii, Boris; Sarafanov, Oleg
2015-01-01
This volume studies electron resonant tunneling in two- and three-dimensional quantum waveguides of variable cross-sections in the time-independent approach. Mathematical models are suggested for the resonant tunneling and develop asymptotic and numerical approaches for investigating the models. Also, schemes are presented for several electronics devices based on the phenomenon of resonant tunneling. Devices based on the phenomenon of electron resonant tunneling are widely used in electronics. Efforts are directed towards refining properties of resonance structures. There are prospects for building new nanosize electronics elements based on quantum dot systems. However, the role of resonance structure can also be given to a quantum wire of variable cross-section. Instead of an "electrode - quantum dot - electrode" system, one can use a quantum wire with two narrows. A waveguide narrow is an effective potential barrier for longitudinal electron motion along a waveguide. The part of the waveguide between ...
Directory of Open Access Journals (Sweden)
Viscardi Massimo
2016-12-01
Full Text Available Successful implementation of an active vibration control system is strictly correlated to the exact knowledge of the dynamic behavior of the system, of the excitation level and spectra and of the sensor and actuator’s specification. Only the correct management of these aspects may guarantee the correct choice of the control strategy and the relative performance. Within this paper, some preliminary activities aimed at the creation of a structurally simple, cheap and easily replaceable active control systems for metal panels are discussed. The final future aim is to control and to reduce noise, produced by vibrations of metal panels of the body of a car. The paper is focused on two points. The first one is the realization of an electronic circuit for Synchronized Shunted Switch Architecture (SSSA with the right dimensioning of the components to control the proposed test article, represented by a rectangular aluminum plate. The second one is a preliminary experimental study on the test article, in controlled laboratory conditions, to compare performances of two possible control approach: SSSA and a feed-forward control approach. This comparison would contribute to the future choice of the most suitable control architecture for the specific attenuation of structure-born noise related to an automotive floor structure under deterministic (engine and road-tyre interaction and stochastic (road-tyre interaction and aerodynamic forcing actions.
Compact on-Chip Temperature Sensors Based on Dielectric-Loaded Plasmonic Waveguide-Ring Resonators
Directory of Open Access Journals (Sweden)
Sergey I. Bozhevolnyi
2011-02-01
Full Text Available The application of a waveguide-ring resonator based on dielectric-loaded surface plasmon-polariton waveguides as a temperature sensor is demonstrated in this paper and the influence of temperature change to the transmission through the waveguide-ring resonator system is comprehensively analyzed. The results show that the roundtrip phase change in the ring resonator due to the temperature change is the major reason for the transmission variation. The performance of the temperature sensor is also discussed and it is shown that for a waveguide-ring resonator with the resonator radius around 5 mm and waveguide-ring gap of 500 nm which gives a footprint around 140 µm2, the temperature sensitivity at the order of 10−2 K can be achieved with the input power of 100 mW within the measurement sensitivity limit of a practical optical detector.
Optical Slot-Waveguide Based Biochemical Sensors
Directory of Open Access Journals (Sweden)
Carlos Angulo Barrios
2009-06-01
Full Text Available Slot-waveguides allow light to be guided and strongly confined inside a nanometer-scale region of low refractive index. Thus stronger light-analyte interaction can be obtained as compared to that achievable by a conventional waveguide, in which the propagating beam is confined to the high-refractive-index core of the waveguide. In addition, slot-waveguides can be fabricated by employing CMOS compatible materials and technology, enabling miniaturization, integration with electronic, photonic and fluidic components in a chip, and mass production. These advantages have made the use of slot-waveguides for highly sensitive biochemical optical integrated sensors an emerging field. In this paper, recent achievements in slot-waveguide based biochemical sensing will be reviewed. These include slot-waveguide ring resonator based refractometric label-free biosensors, label-based optical sensing, and nano-opto-mechanical sensors.
Directory of Open Access Journals (Sweden)
Živković Predrag M.
2004-01-01
Full Text Available The possibility of the electro less deposition of chromium onto aluminum was investigated in order to improve non-printing element properties. It was determined that the electrochemical deposition of trivalent chromium was possible from alkaline solutions. The presence of chromium was confirmed by the EDAX procedure in three different laboratories. The influence of chromium on the wet ability of the nonprinting elements of the printing form was examined by drop spreading. Specimens were examined by pouring distilled water in drops onto the surface of the specimen. The picture of the drop was taken by a digital camera from two directions, in order to measure the diameter of the spreaded drop (a measuring gauge was recorded together with the drop and contact angle. The chromium-treated samples showed increased wettability compared with the non-chromium-treated samples. Improvement of the non-printing elements was confirmed during a printing test that was performed under real printing conditions. The purity of the prints made by two types of printing forms was analyzed in two ways: based on densitometric measurements and based on statistical analysis of the scanned print. Both methods of analysis of the control prints showed that the control prints made from chromium-treated specimens were purer than the prints made from the non-chromium-treated specimens. Considering that all the conditions of making the printing forms and the printing conditions, except the electro less deposition procedure were the same, it could be concluded that the electro less deposited layer of chromium improved the printing properties of the offset printing form because of the increased wettability.
Institute of Scientific and Technical Information of China (English)
Sun Wen-Qian; Liu Yu-Min; Wang Dong-Lin; Han Li-Hong; Guo Xuan; Yu Zhong-Yuan
2013-01-01
We investigate the effect of disorder and mechanical deformation on a two-dimensional photonic crystal waveguide.The dispersion characteristics and transmittance of the waveguide are studied using the finite element method.Results show that the geometric change of the dielectric material perpendicular to the light propagation direction has a larger influence on the waveguide characteristics than that parallel to the light propagation direction.Mechanical deformation has an obvious influence on the performance of the waveguide.In particular,longitudinal deformed structure exhibits distinct optical characteristics from the ideal one.Studies on this work will provide useful guideline to the fabrication and practical applications based on photonic crystal waveguides.
Quantum waveguides with corners
Directory of Open Access Journals (Sweden)
Raymond Nicolas
2012-04-01
Full Text Available The simplest modeling of planar quantum waveguides is the Dirichlet eigenproblem for the Laplace operator in unbounded open sets which are uniformly thin in one direction. Here we consider V-shaped guides. Their spectral properties depend essentially on a sole parameter, the opening of the V. The free energy band is a semi-infinite interval bounded from below. As soon as the V is not flat, there are bound states below the free energy band. There are a finite number of them, depending on the opening. This number tends to infinity as the opening tends to 0 (sharply bent V. In this situation, the eigenfunctions concentrate and become self-similar. In contrast, when the opening gets large (almost flat V, the eigenfunctions spread and enjoy a different self-similar structure. We explain all these facts and illustrate them by numerical simulations. La modélisation la plus simple des guides d’ondes quantiques plans est le problème aux valeurs propres pour le laplacien dans des ouverts non bornés qui sont fins dans une direction. Ici nous considérons des guides en forme de V. Leurs propriétés spectrales dépendent essentiellement d’un seul paramètre, l’ouverture du V. La bande d’énergie libre est un intervalle semi-infini borné inférieurement. Dès que le V n’est pas plat, il existe des états liés sous la bande d’énergie libre. Ils sont en nombre fini, fonction de l’ouverture. Ce nombre tend vers l’infini quand l’ouverture tend vers 0 (V très refermé. Dans cette situation, les fonctions propres se concentrent et deviennent auto-similaires. À l’opposé, quand l’ouverture est grande (V très aplati, les fonctions propres s’étalent et jouissent d’une autre structure auto-similaire. Nous expliquons tous ces résultats et les illustrons par des expériences numériques.
Optical waveguides in laser crystals
Pollnau, Markus; Romanyuk, Yaroslav E.
2007-01-01
This article reviews the recent research on different types of planar and channel crystalline optical waveguides, fabrication methods such as liquid phase epitaxy, pulsed laser deposition, thermal bonding, reactive ion or ion beam etching, wet chemical etching, ion in-diffusion, proton exchange, ion
Glass Waveguides for Periodic Poling
DEFF Research Database (Denmark)
Fage-Pedersen, Jacob; Jacobsen, Rune Shim; Kristensen, Martin
2005-01-01
Planar silica-based waveguide devices have been developed for second-harmonic generation by poling with periodic electrodes. We show that detrimental charge transport can occur along interfaces, but with proper choice of fabrication, high-quality devices are obtained....
Dielectric waveguide amplifiers and lasers
Pollnau, Markus
The performance of semiconductor amplifiers and lasers has made them the preferred choice for optical gain on a micro-chip. In the past few years, we have demonstrated that also rare-earth-ion-doped dielectric waveguides show remarkable performance, ranging from a small-signal gain per unit length
Glass Waveguides for Periodic Poling
DEFF Research Database (Denmark)
Fage-Pedersen, Jacob; Jacobsen, Rune Shim; Kristensen, Martin
2005-01-01
Planar silica-based waveguide devices have been developed for second-harmonic generation by poling with periodic electrodes. We show that detrimental charge transport can occur along interfaces, but with proper choice of fabrication, high-quality devices are obtained....
Photonic-crystal waveguide biosensor
DEFF Research Database (Denmark)
Skivesen, Nina; Têtu, Amélie; Kristensen, Martin
2007-01-01
A photonic-crystal waveguide sensor is presented for biosensing. The sensor is applied for refractive index measurements and detection of protein-concentrations. Concentrations around 10 μg/ml (0.15μMolar) are measured with excellent signal to noise ratio, and a broad, dynamic refractive index se...
Coupled-resonator optical waveguides
DEFF Research Database (Denmark)
Raza, Søren; Grgic, Jure; Pedersen, Jesper Goor
2010-01-01
Coupled-resonator optical waveguides hold potential for slow-light propagation of optical pulses. The dispersion properties may adequately be analyzed within the framework of coupled-mode theory. We extend the standard coupled-mode theory for such structures to also include complex-valued paramet...
Parabolic tapers for overmoded waveguides
Doane, J.L.
1983-11-25
A waveguide taper with a parabolic profile, in which the distance along the taper axis varies as the square of the tapered dimension, provides less mode conversion than equal length linear tapers and is easier to fabricate than other non-linear tapers.
一种简易实用的开口剪切腹板有限元建模方法%NEW CONCISE FINITE ELEMENT MODELING METHOD OF SHEARING PLATE WITH CUTOUT
Institute of Scientific and Technical Information of China (English)
吴存利; 段世慧; 孙侠生; 方同
2011-01-01
A new concise finite element modeling of shearing plate with a cutout is investigated. An equivalent thickness method is proposed and the equivalent thickness formulas of the plates with an elliptical or rectangle-arc cutout are derived considering that the center of the elliptical or rectangle-arc cutout is not consistent with that of the plate and the edge of the cutout is reinforced. To verify the accuracy of the equivalent thickness method, the finite element analyses of a box with two kinds of cutouts modeled with the equivalent thickness method are carried out by using MSC. Nastran and the displacements of the boxes are acquired for both cases. The results show that the displacements obtained by the equivalent thickness modeling method agree well with that obtained by the traditional method and the relative errors are less than 2% , which verifies preliminarily that the equivalent thickness modeling method given in the paper is highly efficient and possesses good adaptability.%研究含开口剪切腹板结构简易的有限元建模技术,提出当量厚度的有限元建模方法,给出内含椭圆形开口以及长方形和弧形组合开口腹板的当量厚度计算式.该计算式考虑腹板形心与开口中心不重合及开口边缘有加强件.为了验证文中提出的当量厚度有限元建模方法的正确性,采用MSC.Nastran分别对含两种开口墙腹板的盒段进行有限元建模分析,并分别与常规的网格细化的有限元建模分析结果进行比较.结果表明,所给出的当量厚度建模方法与常规网格细化的建模方法吻合很好,相对误差不大于2.0％,验证了所提出建模方法的正确性和有效性.
Plate shell structures of glass
DEFF Research Database (Denmark)
Bagger, Anne
. This modelling technique is used to model a plate shell structure with a span of 11.5 meters in the FE software \\textsc{Abaqus}. The structure is analyzed with six different connection details with varying stiffness characteristics, to investigate the influence of these characteristics on the structural effects...... University, a script has been developed for an automated generation of a given plate shell geometry and a corresponding finite element (FE) model. A suitable FE modelling technique is proposed, suggesting a relatively simple method of modelling the connection detail's stiffness characteristics....... Based on these investigations, and FE analysis of other plate shell models, the structural behaviour is described. Possible methods of estimating the stresses in a given plate shell structure are proposed. The non-linear behaviour of a plate shell structure is investigated for varying parameters...
Mendoza-Suárez, A.; Pérez-Aguilar, H.
2016-09-01
We present several numerical integral methods for the study of a photonic crystal waveguide, formed by two parallel conducting plates and an array of circular inclusions involving a conducting material and a metamaterial. Band structures and reflectance were calculated, for infinite and finite photonic crystal waveguides, respectively. The numerical results obtained show that the numerical methods applied provide good accuracy and efficiency. An interesting detail that resulted from this study was the appearance of a propagating mode in a band gap due to defects in the middle of the photonic crystal waveguide. This is equivalent to dope a semiconductor to introduce allowed energy states within a band gap. Our main interest in this work is to model photonic crystal waveguides that involve left-handed materials (LHMs). For the specific LHM considered, a surface plasmon mode on the vacuum-LHM interface was found.
Finite element simulation of FRP plates impacted by fragments%破片侵彻纤维复合材料板的有限元数值模拟
Institute of Scientific and Technical Information of China (English)
谢恒; 吕振华
2012-01-01
采用有限元方法对几种不同外形和材料的破片模拟弹垂直侵彻玻璃纤维增强复合材料层合板的动态响应过程进行了模拟分析,研究了靶板有限元模型网格尺度对抗破片侵彻特性模拟计算结果的影响,分析了靶板直径和边界约束条件等因素对复合材料板的抗破片特性的影响。对于厚度为4.0mm以上的较厚靶板,几种常用的13.4g钢质破片模拟弹的外形和材料的差异对侵彻能力影响较小。与已有文献中的实验结果的比较表明：当有限元网格尺度接近复合材料单层厚度时,计算结果的精度较好;当靶板直径大于一个与靶板材料波速相关的临界直径时,靶板直径、边界约束条件对破片模拟弹剩余速度的影响可忽略;完全固支条件的计算结果比简支或自由边界条件更接近于大尺寸靶板的计算结果。%The dynamic response of fiber reinforced composites impacted by fragment simulating projectiles（FSPs） of different shapes and materials was simulated with the finite element method.Studies were performed on the influence of the target＇s finite element mesh size to the particle penetration.The effects of the target plate diameter and boundary conditions on the ballistic analysis results were also investigated.The differences in the perforation probability of 13.4 g steel FSPs with different shapes and materials is negligible for composite targets thicker than about 4 mm.The numerically predicted ballistic limit velocities agree well with experimental results only with mesh sizes close to the ply layer thickness.If the target plate diameter is larger than a critical value related to the plate material wave speed,the target plate diameter and boundary conditions have almost no effect on the predicted fragment residual velocity.Simulations with fully clamped boundary condition are closer to those of a large target plate than with simply supported boundaries or fully free conditions.
A Directly-Written Monolithic Waveguide-Laser Incorporating a DFB Waveguide-Bragg Grating
Marshall, Graham D; Ams, Martin; Piper, James A; Withford, Michael J
2008-01-01
We report the fabrication and performance of the first C-band directly-written monolithic waveguide-laser. The waveguide-laser device was created in an Erbium and Ytterbium doped phosphate glass host and consisted of an optical waveguide that included a distributed feedback Bragg grating structure. The femtosecond laser direct-write technique was used to create both the waveguide and the waveguide-Bragg grating simultaneously and in a single processing step. The waveguide-laser was optically pumped at approximately 980 nm and lased at 1537nm with a bandwidth of less than 4 pm.
Ultrasonic Waveguide Sensor Using a Leaky Lamb Wave for Under-Sodium Viewing
Joo, Young-Sang; Lee, Jae-Han
2010-02-01
A plate-type ultrasonic waveguide sensor using a leaky Lamb wave has been developed for the under-sodium viewing of a reactor core and in-vessel structures of a sodium-cooled fast reactor (SFR). An A0 Lamb wave mode is utilized in the waveguide sensor for the single mode generation and the effective radiation capability in a fluid. A radiation beam steering technique is presented which is achieved by the frequency tuning of the excitation pulse in the frequency range of the A0 Lamb wave mode which the group velocity is not dispersive and the phase velocity is dispersive. The long distance propagation ability and C-scan imaging performance have been demonstrated successfully by experimental feasibility tests of the waveguide sensor.
Coherent random lasing from liquid waveguide gain layer containing silica nanoparticles
Ye, Lihua; Feng, Yangyang; Lu, Changgui; Hu, Guohua; Cui, Yiping
2016-10-01
A unidirectional coherent random laser is constructed by a sandwich structure consisting of two polydimethylsiloxane plates and a highly transparent ultra-thin liquid active layer embedded with silica nanoparticles (NPs). The optical feedback of the random laser is provided by both strong waveguide confinement and the SiO2 NPs’ multiple scattering. Compared with random laser in a quartz cuvette, the pump threshold is only 700 µJ cm-2. The lowest threshold is obtained in an optimum concentration of silica NPs. The change of peak positions in the liquid waveguide structure is larger than that in the quartz cuvette for different solvents. The peak-shift of the emission wavelength is more sensitive in the liquid waveguide structure, which is a promising platform for bio-chemical and bio-sensing applications.
Super energy flows in a waveguide filled with air and left-handed materials
Institute of Scientific and Technical Information of China (English)
Yu Guan-Xia; Cui Tie-Jun
2008-01-01
The phenomena of super energy flows are studied theoretically and numerically in a parallel-plate waveguide which is filled with two layered equally-thick different media,i.e.air and specific left-handed materials (LHM) with 6r1 =-1/(1+5) + iγ and μr1=-(1 +δ) + iγ.In this special waveguide,two-directional super-energy flows are excited by a three-dimensional horizontal electric dipole at the same time,which has transmission patterns different from those of two-dimensional source and three-dimensional vertical electric dipole.We also show that the retardation and loss in LHM are sensitive to the amplitude of super power densities,and the dimensions of waveguide determine the propagating modes,which makes super energy flows more practical.
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....
Longitudinal Modes along Thin Piezoelectric Waveguides for Liquid Sensing Applications
Directory of Open Access Journals (Sweden)
Cinzia Caliendo
2015-06-01
Full Text Available The propagation of longitudinally polarized acoustic modes along thin piezoelectric plates (BN, ZnO, InN, AlN and GaN is theoretically studied, aiming at the design of high frequency electroacoustic devices suitable for work in liquid environments. The investigation of the acoustic field profile across the plate revealed the presence of longitudinally polarized Lamb modes, travelling at velocities close to that of the longitudinal bulk acoustic wave propagating in the same direction. Such waves are suitable for the implementation of high-frequency, low-loss electroacoustic devices operating in liquid environments. The time-averaged power flow density, the phase velocity and the electroacoustic coupling coefficient K2 dispersion curves were studied, for the first (S0 and four higher order (S1, S2, S3, S4 symmetrical modes for different electrical boundary conditions. Two electroacoustic coupling configurations were investigated, based on interdigitated transducers, with or without a metal floating electrode at the opposite plate surface. Enhanced performances, such as a K2 as high as 8.5% and a phase velocity as high as 16,700 m/s, were demostrated for the ZnO- and BN-based waveguides, as an example. The relative velocity changes, and the inertial and viscous sensitivities of the first symmetric and anti-symmetric mode, S0 and A0, propagating along thin plates bordered by a viscous liquid were derived using the perturbation approach. The present study highlights the feasibility of the piezoelectric waveguides to the development of high-frequency, integrated-circuits compatible electroacoustic devices suitable for working in liquid environment.
AN ADAPTIVE INVERSE ITERATION FEM FOR THE INHOMOGENEOUS DIELECTRIC WAVEGUIDES
Institute of Scientific and Technical Information of China (English)
Jianhua Yuan
2007-01-01
We introduce an adaptive finite element method for computing electromagnetic guided waves in a closed, inhomogeneous, pillared three-dimensional waveguide at a given frequency based on the inverse iteration method. The problem is formulated as a generalized eigenvalue problems. By modifying the exact inverse iteration algorithm for the eigenvalue problem, we design a new adaptive inverse iteration finite element algorithm. Adaptive finite element methods based on a posteriori error estimate are known to be successful in resolving singularities of eigenfunctions which deteriorate the finite element convergence.We construct a posteriori error estimator for the electromagnetic guided waves problem.Numerical results are reported to illustrate the quasi-optimal performance of our adaptive inverse iteration finite element method.
Ion-exchanged glass waveguides with low birefringence for a broad range of waveguide widths.
Yliniemi, Sanna; West, Brian R; Honkanen, Seppo
2005-06-01
Optical communications networks require integrated photonic components with negligible polarization dependence, which typically means that the waveguides must feature very low birefringence. Recent studies have shown that waveguides with low birefringence can be obtained, e.g., by use of silica-on-silicon waveguides or buried ion-exchanged glass waveguides. However, many integrated photonic circuits consist of waveguides with varying widths. Therefore low birefringence is consequently required for waveguides having different widths. This is a difficult task for most waveguide fabrication technologies. We present experimental results on waveguide birefringence for buried silver-sodium ion-exchanged glass waveguides. We show that the waveguide birefringence of the order of 10(-6) for waveguide mask opening widths ranging from 2 to 10 microm can be obtained by postprocessing the sample through annealing at an elevated temperature. The measured values are in agreement with the values calculated with our modeling software for ion-exchanged glass waveguides. This unique feature of ion-exchanged waveguides may be of significant importance in a wide variety of integrated photonic circuits requiring polarization-independent operation.
Travelling-wave transmitted with a simple waveguide for rodents Magnetic Resonance Imaging at 9.4 T
Baeza, Richard; Marrufo, Oscar; Martin, Rodrigo; Solis, Sergio; Gore, John; Rodriguez, Alfredo O
2015-01-01
Standard coils can cause inhomogeneities due to the standing wave patterns at ultra high field MRI. This B1 inhomogeneity can be overcome using the travelling-wave MRI (twMRI) approach. The ma- jority of twMRI research has been done with clinical MRI scanners at 7T or above. More recently, this concept has been also used with animal MRI systems, using circular-cross section waveguides and dielectric materials for both type of scanners. We have demonstrated that twMRI can be used at 3 T with clinical systems and a parallel-plate waveguide. Here, we investigated the use of a parallel- plate waveguide and a RF circular coil to generate rat images with an animal MRI at 9.4 T.
Waveguide-coupled nanowire as an optical antenna.
Arnaud, Laurent; Bruyant, Aurélien; Renault, Mikael; Hadjar, Yassine; Salas-Montiel, Rafael; Apuzzo, Aniello; Lérondel, Gilles; Morand, Alain; Benech, Pierre; Le Coarer, Etienne; Blaize, Sylvain
2013-11-01
We study the optical coupling between a gold nanowire and a silver ion-exchanged waveguide, with special emphasis on the nanowire antenna radiation pattern. We measure the radiation patterns of waveguide-coupled gold nanowires with a height of 70 nm and width of 50 or 150 nm in the 450-700 nm spectral range for TE and TM polarizations. We perform a systematic theoretical study on the wavelength, polarization, nanowire size, and material dependences on the properties of the radiation pattern. We also give some elements concerning absorption and near-field. Experiments and calculations show localized plasmon resonance for the polarization orthogonal to the wire (far-field resonance at 580 nm for the smallest wire and 670 nm for the widest). It is shown that a great variety of radiation patterns can be obtained, together with a high sensitivity to a change of one parameter, particularly near-resonance.
Loop-mirror-based slot waveguide refractive index sensor
Directory of Open Access Journals (Sweden)
Jun-long Kou
2012-12-01
Full Text Available Loop mirror has been widely used in fiber optical devices and systems for it provides a smart way to make use of the fiber birefringence properties and can enhance the sensitivity greatly. On the other hand, slot waveguide is very promising for optical sensing applications because of their peculiar spatial mode profile. In this paper, we propose and analyze a loop-mirror-based slot waveguide (LMSW sensor which can be routinely fabricated in modern high-volume complementary metal-oxide–semiconductor (CMOS process. The finite element method (FEM simulation results show that the birefringence can be as high as 0.8 which is orders of magnitude than that in conventional birefringent fiber loop mirror. High sensitivity up to 6 × 103 nm/RIU (refractive index unit is achieved by this scheme.
Digital Waveguides versus Finite Difference Structures: Equivalence and Mixed Modeling
Directory of Open Access Journals (Sweden)
Karjalainen Matti
2004-01-01
Full Text Available Digital waveguides and finite difference time domain schemes have been used in physical modeling of spatially distributed systems. Both of them are known to provide exact modeling of ideal one-dimensional (1D band-limited wave propagation, and both of them can be composed to approximate two-dimensional (2D and three-dimensional (3D mesh structures. Their equal capabilities in physical modeling have been shown for special cases and have been assumed to cover generalized cases as well. The ability to form mixed models by joining substructures of both classes through converter elements has been proposed recently. In this paper, we formulate a general digital signal processing (DSP-oriented framework where the functional equivalence of these two approaches is systematically elaborated and the conditions of building mixed models are studied. An example of mixed modeling of a 2D waveguide is presented.
Electromagnetic Scattering at the Waveguide Step between Equilateral Triangular Waveguides
Directory of Open Access Journals (Sweden)
Ana Morán-López
2016-01-01
Full Text Available The analysis of the electromagnetic scattering at discontinuities between equilateral triangular waveguides is studied. The complete electromagnetic solution is derived using analytical closed form expressions for the mode spectrum of the equilateral waveguide. The mathematical formulation of the electromagnetic scattering problem is based on the quasi-analytical Mode-Matching method. This method benefits from the electromagnetic field division into symmetries as well as from the plane wave formulation presented for the expressions involved. The unification of the surface integrals used in the method thanks to the plane wave formulation is revealed, leading to expressions that are very well suited for its implementation in an electromagnetic analysis and design code. The obtained results for some cases of interest (building blocks for microwave components for communication systems are verified using other numerical methods included in a commercial software package, showing the potential of the presented approach based on quasi-analytic expressions.
Low-noise on-chip frequency conversion by four-wave-mixing Bragg scattering in SiNx waveguides
Agha, Imad; Thurston, Bryce; Srinivasan, Kartik
2012-01-01
Low-noise, tunable wavelength-conversion through non-degenerate four-wave mixing Bragg scattering in SiNx waveguides is experimentally demonstrated. Finite element method simulations of waveguide dispersion are used with the split-step Fourier method to predict device performance, and indicate a strong dependence of the conversion efficiency on phase matching, which is controlled by the waveguide geometry. Two 1550 nm wavelength band pulsed pumps are used to achieve tunable conversion of a 980 nm signal over a range of 5 nm with a peak conversion efficiency of \\approx 5 %. The demonstrated Bragg scattering process is suitable for frequency conversion of quantum states of light.
Yang, Peidong; Law, Matt; Sirbuly, Donald J.; Johnson, Justin C.; Saykally, Richard; Fan, Rong; Tao, Andrea
2012-10-02
Nanoribbons and nanowires having diameters less than the wavelength of light are used in the formation and operation of optical circuits and devices. Such nanostructures function as subwavelength optical waveguides which form a fundamental building block for optical integration. The extraordinary length, flexibility and strength of these structures enable their manipulation on surfaces, including the precise positioning and optical linking of nanoribbon/wire waveguides and other nanoribbon/wire elements to form optical networks and devices. In addition, such structures provide for waveguiding in liquids, enabling them to further be used in other applications such as optical probes and sensors.
Institute of Scientific and Technical Information of China (English)
Yuanliang Chu(初元量); Hanyi Zhang(张汉一)
2003-01-01
The dimensions of input waveguide and output waveguide of arrayed waveguide gratings (AWGs) determinethe crosstalk, insertion loss and 1-dB bandwidth. In cascaded optical add/drop multiplexers (OADMs),the value of these parameters will largely affect the power penalty of system. The power penalty ofcascaded OADMs is calculated with different waveguide dimensions of AWGs in this paper. Consideringof wavelength misalignment, an optimization design of AWGs is obtained.
Wideband unbalanced waveguide power dividers and combiners
Energy Technology Data Exchange (ETDEWEB)
Halligan, Matthew; McDonald, Jacob Jeremiah; Strassner, II, Bernd H.
2016-05-17
The various technologies presented herein relate to waveguide dividers and waveguide combiners for application in radar systems, wireless communications, etc. Waveguide dividers-combiners can be manufactured in accordance with custom dimensions, as well as in accordance with waveguide standards such that the input and output ports are of a defined dimension and have a common impedance. Various embodiments are presented which can incorporate one or more septum(s), one or more pairs of septums, an iris, an input matching region, a notch located on the input waveguide arm, waveguide arms having stepped transformer regions, etc. The various divider configurations presented herein can be utilized in high fractional bandwidth applications, e.g., a fractional bandwidth of about 30%, and RF applications in the Ka frequency band (e.g., 26.5-40 GHz).
Design Procedure for Compact Folded Waveguide Filters
DEFF Research Database (Denmark)
Dong, Yunfeng; Johansen, Tom Keinicke; Zhurbenko, Vitaliy;
Waveguide filters are widely used in communication systems due to low losses and high power handling capabilities. One drawback of the conventional waveguide filters is their large size, especially for low-frequency and high-order realizations. It has been shown that the footprint of conventional...... waveguide resonators can be reduced to one quarter by folding the electric and magnetic fields inside the cavity (J. S. Hong, Microwave Symposium Digest, 2004, Vol. 1, pp. 213-216). This paper presents a novel systematic procedure for designing compact low-loss bandpass filters by using folded waveguide...... resonators. As a design example, a scaled version of a filter specified for a TETRA (Terrestrial Trunked Radio) system has been considered. The folded waveguide filter is designed to fulfil specific requirements, and the design procedure can be easily applied to other folded waveguide filter designs...
Plasmonic coaxial waveguide-cavity devices.
Mahigir, Amirreza; Dastmalchi, Pouya; Shin, Wonseok; Fan, Shanhui; Veronis, Georgios
2015-08-10
We theoretically investigate three-dimensional plasmonic waveguide-cavity structures, built by side-coupling stub resonators that consist of plasmonic coaxial waveguides of finite length, to a plasmonic coaxial waveguide. The resonators are terminated either in a short or an open circuit. We show that the properties of these waveguide-cavity systems can be accurately described using a single-mode scattering matrix theory. We also show that, with proper choice of their design parameters, three-dimensional plasmonic coaxial waveguide-cavity devices and two-dimensional metal-dielectric-metal devices can have nearly identical transmission spectra. Thus, three-dimensional plasmonic coaxial waveguides offer a platform for practical implementation of two-dimensional metal-dielectric-metal device designs.
Systematic Design of Slow Light Waveguides
DEFF Research Database (Denmark)
Wang, Fengwen
Light can propagate much slower in photonic crystal waveguides and plasmonic waveguides than in vacuum. Slow light propagation in waveguides shows broad prospects in the terabit communication systems. However, it causes severe signal distortions and displays large propagation loss. Moreover...... two different parameterizations. Detailed comparisons show that the bandwidth of slow light propagation can be significantly enhanced by allowing irregular geometries in the waveguides. To mitigate the propagation loss due to scattering in the photonic crystal waveg- uides, an optimization problem...... is formulated to minimize the average propagation loss of the designed modes. The presented approach is employed to design a free-topology slow light waveguide. Numerical result illustrates that slow light propagation in the optimized waveguide displays significantly suppressed propagation loss while keeping...
Long-Period Gratings in Planar Optical Waveguides
Institute of Scientific and Technical Information of China (English)
Kin; Seng; Chiang
2003-01-01
Our progress in the study of long-period gratings (LPGs) in planar optical waveguides is reviewed. In particular, experimental LPGs in glass and polymer waveguides are presented to demonstrate the potential of LPG-based waveguide devices.
Long-Period Gratings in Planar Optical Waveguides
Institute of Scientific and Technical Information of China (English)
Kin Seng Chiang
2003-01-01
Our progress in the study of long-period gratings (LPGs) in planar optical waveguides is reviewed. In particular,experimental LPGs in glass and polymer waveguides are presented to demonstrate the potential of LPG-based waveguide devices.
Multilayer cladding with hyperbolic dispersion for plasmonic waveguides
DEFF Research Database (Denmark)
Babicheva, Viktoriia; Shalaginov, Mikhail Y.; Ishii, Satoshi;
2015-01-01
We study the properties of plasmonic waveguides with a dielectric core and multilayer metal-dielectric claddings that possess hyperbolic dispersion. The waveguides hyperbolic multilayer claddings show better performance in comparison to conventional plasmonic waveguides. © OSA 2015....
DEFF Research Database (Denmark)
Skivesen, Nina
This work concerns planar optical waveguide sensors for biosensing applications, with the focus on deep-probe sensing for micron-scale biological objects like bacteria and whole cells. In the last two decades planar metal-clad waveguides have been brieflyintroduced in the literature applied...... for various biosensing applications, however a thorough study of the sensor configurations has not been presented, but is the main subject of this thesis. Optical sensors are generally well suited for bio-sensing asthey show high sensitivity and give an immediate response for minute changes in the refractive...... index of a sample, due to the high sensitivity of optical bio-sensors detection of non-labeled biological objects can be performed. The majority of opticalsensors presented in the literature and commercially available optical sensors are based on evanescent wave sensing, however most of these sensors...
Reverse-symmetry waveguides: Theory and fabrication
DEFF Research Database (Denmark)
Horvath, R.; Lindvold, Lars René; Larsen, N.B.
2002-01-01
We present an extensive theoretical analysis of reverse-symmetry waveguides with special focus on their potential application as sensor components in aqueous media and demonstrate a novel method for fabrication of such waveguides. The principle of reverse symmetry is based on making the refractiv...... has the advantage of deeper penetration of the evanescent electromagnetic field into the cover medium, theoretically permitting higher sensitivity to analytes compared to traditional waveguide designs. We present calculated sensitivities and probing depths of conventional and reverse...
Talbot Effect in Three Waveguide Arrays
Institute of Scientific and Technical Information of China (English)
LI Zhi; ZHOU Hai-Feng; YANG Jian-Yi; JIANG Xiao-Qing
2008-01-01
By taking the coupling between the non-neighbourhood waveguides into account, the coupling characteristic of three waveguide arrays is analysed. The strong coupling equation of three waveguides is dealt with Laplace transform and LU decomposition. The general field evolution equation is obtained by inversion of the Laplace transform. The results show that the self-imaging conditions (Talbot effect) do not satisfy in general. The theoretical predictions are in good agreement with the BPM simulations.
Two-dimensional Kagome photonic bandgap waveguide
DEFF Research Database (Denmark)
Nielsen, Jens Bo; Søndergaard, Thomas; Libori, Stig E. Barkou;
2000-01-01
The transverse-magnetic photonic-bandgap-guidance properties are investigated for a planar two-dimensional (2-D) Kagome waveguide configuration using a full-vectorial plane-wave-expansion method. Single-moded well-localized low-index guided modes are found. The localization of the optical modes...... is investigated with respect to the width of the 2-D Kagome waveguide, and the number of modes existing for specific frequencies and waveguide widths is mapped out....
Digital Waveguide Adiabatic Passage Part 1: Theory
Vaitkus, Jesse A; Greentree, Andrew D
2016-01-01
Spatial adiabatic passage represents a new way to design integrated photonic devices. In conventional adiabatic passage designs require smoothly varying waveguide separations. Here we show modelling of adiabatic passage devices where the waveguide separation is varied digitally. Despite digitisation, our designs show robustness against variations in the input wavelength and refractive index contrast of the waveguides relative to the cladding. This approach to spatial adiabatic passage opens new design strategies and hence the potential for new photonics devices.
Energy Technology Data Exchange (ETDEWEB)
Aguilas, F.; Moneva, M. A.; Garcia Ramirez, L.; Lopez Jimenez, J.; Diaz Diaz, J.
1971-07-01
It is analysed the thermal distribution of a fuel element of tubular plates irradiated in the JEN-1 reactor in the case of shaft locking of the primary cooling pump without opening the emergency gate. The fuel element hottest channel is studied in the position of maximum neutronic flux for three reactor power levels: 3 Hw (maximum reactor power), 2 Mw and 1 Hw. (Author) 8 refs.
Optical Waveguide Sensing and Imaging
Bock, Wojtek J; Tanev, Stoyan
2008-01-01
The book explores various aspects of existing and emerging fiber and waveguide optics sensing and imaging technologies including recent advances in nanobiophotonics. The focus is both on fundamental and applied research as well as on applications in civil engineering, biomedical sciences, environment, security and defence. The main goal of the multi-disciplinarry team of Editors was to provide an useful reference of state-of-the-art overviews covering a variety of complementary topics on the interface of engineering and biomedical sciences.
Tantawi, Sami G.; Dolgashev, Valery A.; Yeremian, Anahid D.
2016-03-15
A high-power microwave RF window is provided that includes a cylindrical waveguide, where the cylindrical waveguide includes a ceramic disk concentrically housed in a central region of the cylindrical waveguide, a first rectangular waveguide, where the first rectangular waveguide is connected by a first elliptical joint to a proximal end of the cylindrical waveguide, and a second rectangular waveguide, where the second rectangular waveguide is connected by a second elliptical joint to a distal end of the cylindrical waveguide.
Full Text Available ... A A A Listen En Español Create Your Plate Create Your Plate is a simple and effective ... and that your options are endless. Create Your Plate! Click on the plate sections below to add ...
Resonant waveguide grating imagers for single cell analysis and high throughput screening
Fang, Ye
2015-08-01
Resonant waveguide grating (RWG) systems illuminate an array of diffractive nanograting waveguide structures in microtiter plate to establish evanescent wave for measuring tiny changes in local refractive index arising from the dynamic mass redistribution of living cells upon stimulation. Whole-plate RWG imager enables high-throughput profiling and screening of drugs. Microfluidics RWG imager not only manifests distinct receptor signaling waves, but also differentiates long-acting agonism and antagonism. Spatially resolved RWG imager allows for single cell analysis including receptor signaling heterogeneity and the invasion of cancer cells in a spheroidal structure through 3-dimensional extracellular matrix. High frequency RWG imager permits real-time detection of drug-induced cardiotoxicity. The wide coverage in target, pathway, assay, and cell phenotype has made RWG systems powerful tool in both basic research and early drug discovery process.
Improved optical planar waveguides for lasers Project
National Aeronautics and Space Administration — Demonstrate efficacy of a novel growth technique for planar waveguides (PWG) Enable PWG laser technology with improved performance, efficiency and manufacturability....
A New Type of Terahertz Waveguides
Institute of Scientific and Technical Information of China (English)
LOU Shu-Qin; GUO Tie-Ying; FANG Hong; LI Hong-Lei; JIAN Shui-Sheng
2006-01-01
A new type of THz waveguides, which employs a solid polyethylene rod as the core and polyethylene tubes in a periodic array of square lattice as the cladding, is proposed. Optical properties of this new THz waveguide, especially in dispersion, confinement loss and single mode property, are investigated in detail with the plane wave expansion method and the beam propagation method. Numerical results demonstrate that the new THz waveguide can reach not only low dispersion but also low confinement loss at single mode propagation. Therefore, the square lattice structure is a better candidate as THz waveguides than the triangular ones.
Graded-index planar waveguide solar concentrator.
Bouchard, Sébastien; Thibault, Simon
2014-03-01
Planar waveguides are useful to transport, concentrate and distribute light uniformly over large dimensions. Their capacity to collect and gather light efficiently over a large distance is interesting for many applications, like backlighting and solar concentration. For these reasons, the possibility of making them even more efficient could be of considerable interest for the community. The observation of the ray path inside a graded-index (GRIN) fiber inspired the development of a similar technology inside planar waveguides. In this Letter, we show that it has the potential to dramatically increase the efficiency of planar waveguide-based solar concentrators or backlighting using GRIN planar waveguides.
Quiroga, J. E.; Mujica, L.; Villamizar, R.; Ruiz, M.; Camacho, J.
2017-05-01
This paper presents an approach to calculate dispersion curves for homogeneous and isotropic plates subject to stress, via Semi-Analytical Finite Element and the Effective Elastic Constants, since stresses in the waveguide modify the phase and group velocities of the lamb waves. In the proposed methodology an isotropic specimen subjected to anisotropic loading is emulated by proposing an equivalent stress-free anisotropic specimen. This approximation facilitates determining the dispersion curves by using the well-studied numerical solution for the stress-free cases. The lamb wave in anisotropic materials can be studied by means of the Effective Elastic Constants, which reduces the complexity of the numerical implementation. Finally, numerical data available in literature were used to validate the proposed methodology, where it could be demonstrated its effectiveness as approximated method.
Thin plate neotectonic models of the Australian plate
Burbidge, D. R.
2004-10-01
Thin plate finite element models of the neotectonic deformation of the Australian plate have been calculated in order to estimate the stress and strain rate within the plate, specifically concentrating on the Australian continent. The model includes plate-bounding faults, an anelastic brittle-ductile layered rheology and the option of laterally varying elevation and heat flow. The results of the models are compared to (1) the velocity of geodetic benchmarks on the Australian plate, (2) the spreading rate of the mid-oceanic ridges along the Australian plate's margins, (3) the direction of the maximum horizontal principal stress, (4) the stress regime within the plate, and (5) the crustal thickness estimated from the depth to the base of Mohorovicic discontinuity's transition zone. A variety of models are tested with a wide range of input parameters. The model with the smallest misfit with observations predicts that the strain rate for most of the Australian continent is approximately 10-17 s-1. This model has a slightly lower strain rate in the central Australia and is higher off the northern coast of Australia than for the rest of the continent. Strain rates of this magnitude would be difficult to observe from geodetic or geologic data for most parts of Australia but would be enough to generate much of the seismicity that has been observed over the last century.
Electro-optical circuit board with single-mode glass waveguide optical interconnects
Brusberg, Lars; Neitz, Marcel; Pernthaler, Dominik; Weber, Daniel; Sirbu, Bogdan; Herbst, Christian; Frey, Christopher; Queisser, Marco; Wöhrmann, Markus; Manessis, Dionysios; Schild, Beatrice; Oppermann, Hermann; Eichhammer, Yann; Schröder, Henning; Hâkansson, Andreas; Tekin, Tolga
2016-03-01
A glass optical waveguide process has been developed for fabrication of electro-optical circuit boards (EOCB). Very thin glass panels with planar integrated single-mode waveguides can be embedded as a core layer in printed circuit boards for high-speed board-level chip-to-chip and board-to-board optical interconnects over an optical backplane. Such singlemode EOCBs will be needed in upcoming high performance computers and data storage network environments in case single-mode operating silicon photonic ICs generate high-bandwidth signals [1]. The paper will describe some project results of the ongoing PhoxTroT project, in which a development of glass based single-mode on-board and board-to-board interconnection platform is successfully in progress. The optical design comprises a 500 μm thin glass panel (Schott D263Teco) with purely optical layers for single-mode glass waveguides. The board size is accommodated to the mask size limitations of the fabrication (200 mm wafer level process, being later transferred also to larger panel size). Our concept consists of directly assembling of silicon photonic ICs on cut-out areas in glass-based optical waveguide panels. A part of the electrical wiring is patterned by thin film technology directly on the glass wafer surface. A coupling element will be assembled on bottom side of the glass-based waveguide panel for 3D coupling between board-level glass waveguides and chip-level silicon waveguides. The laminate has a defined window for direct glass access for assembling of the photonic integrated circuit chip and optical coupling element. The paper describes the design, fabrication and characterization of glass-based electro-optical circuit board with format of (228 x 305) mm2.
Bismuth ferrite as low-loss switchable material for plasmonic waveguide modulator
Babicheva, Viktoriia; Zhukovsky, Sergei; Lavrinenko, Andrei
2014-01-01
We propose new designs of plasmonic modulators, which can be utilized for dynamic signal switching in photonic integrated circuits. We study performance of plasmonic waveguide modulator with bismuth ferrite as an active material. The bismuth ferrite core is sandwiched between metal plates (metal-insulator-metal configuration), which also serve as electrodes so that the core changes its refractive index under applied voltage by means of partial in-plane to out-of-plane reorientation of ferroel...
Waveguide piezoelectric micromachined ultrasonic transducer array for short-range pulse-echo imaging
Lu, Y.; Tang, H.; Wang, Q.; Fung, S.; Tsai, J. M.; Daneman, M.; Boser, B. E.; Horsley, D. A.
2015-05-01
This paper presents an 8 × 24 element, 100 μm-pitch, 20 MHz ultrasound imager based on a piezoelectric micromachined ultrasonic transducer (PMUT) array having integrated acoustic waveguides. The 70 μm diameter, 220 μm long waveguides function both to direct acoustic waves and to confine acoustic energy, and also to provide mechanical protection for the PMUT array used for surface-imaging applications such as an ultrasonic fingerprint sensor. The imager consists of a PMUT array bonded with a CMOS ASIC using wafer-level conductive eutectic bonding. This construction allows each PMUT in the array to have a dedicated front-end receive amplifier, which together with on-chip analog multiplexing enables individual pixel read-out with high signal-to-noise ratio through minimized parasitic capacitance between the PMUT and the front-end amplifier. Finite element method simulations demonstrate that the waveguides preserve the pressure amplitude of acoustic pulses over distances of 600 μm. Moreover, the waveguide design demonstrated here enables pixel-by-pixel readout of the ultrasound image due to improved directivity of the PMUT by directing acoustic waves and creating a pressure field with greater spatial uniformity at the end of the waveguide. Pulse-echo imaging experiments conducted using a one-dimensional steel grating demonstrate the array's ability to form a two-dimensional image of a target.
Chen, Yijing; Ho, Seng-Tiong; Krishnamurthy, Vivek
2013-12-20
All-optical switching operation based on manipulation of absorption in a three-waveguide directional coupler is theoretically investigated. The proposed structure consists of one absorptive central waveguide and two identical passive side waveguides. Optically induced absorption change in the central waveguide effectively controls the coupling of light between the two side waveguides, leading to optical switching action. The proposed architecture alleviates the fabrication challenges and waveguide index matching conditions that limit previous demonstrations of similar switching schemes based on a two-waveguide directional coupler. The proposed device accommodates large modal index difference between absorptive and passive waveguides without compromising the switching extinction ratio.
Energy Technology Data Exchange (ETDEWEB)
Joo, Young Sang; Kim, Seok Hun; Lee, Jae Han
2006-02-15
The primary components such as a reactor core, heat exchangers, pumps and internal structures of a liquid metal reactor (LMR) are submerged in hot sodium of reactor vessel. The division 3 of ASME code section XI specifies the visual inspection and continuous monitoring as major in-service inspection (ISI) methods of reactor internal structures. Reactor core and internal structures of LMR can not be visually examined due to an opaque liquid sodium. The under-sodium viewing and remote inspection techniques by using an ultrasonic wave should be applied for the in-service inspection of reactor internals. The remote inspection techniques using ultrasonic wave have been developed and applied for the visualization and ISI of reactor internals. The under sodium viewing technique has a limitation for the application of LMR due to the high temperature and irradiation environment. In this study, an ultrasonic waveguide sensor with a strip plate has been developed for an application to the under-sodium viewing and remote inspection. The Lamb wave propagation of a waveguide sensor has been analyzed and the zero-order antisymmetric A{sub 0} plate wave was selected as the application mode of the sensor. The A{sub 0} plate wave can be propagated in the dispersive low frequency range by using a liquid wedge clamped to the waveguide. A new technique is presented which is capable of steering the radiation beam angle of a waveguide sensor without a mechanical movement of the sensor assembly. The steering function of the ultrasonic radiation beam can be achieved by a frequency tuning method of the excitation pulse in the dispersive range of the A{sub 0} mode. The technique provides an opportunity to overcome the scanning limitation of a waveguide sensor. The beam steering function has been evaluated by an experimental verification. The ultrasonic C-scanning experiments are performed in water and the feasibility of the ultrasonic waveguide sensor has been verified. The various remote
Fuzzy Sliding Mode Control of Plate Vibrations
Manu Sharma; Singh, S. P.
2010-01-01
In this paper, fuzzy logic is meshed with sliding mode control, in order to control vibrations of a cantilevered plate. Test plate is instrumented with a piezoelectric sensor patch and a piezoelectric actuator patch. Finite element method is used to obtain mathematical model of the test plate. A design approach of a sliding mode controller for linear systems with mismatched time-varying uncertainties is used in this paper. It is found that chattering around the sliding surface in the sliding ...
Optimal geometry of nonlinear silicon slot waveguides accounting for the effect of waveguide losses.
Ong, Jun Rong; Chen, Valerian H
2015-12-28
The optimal geometry of silicon-organic hybrid slot waveguides is investigated in the context of the efficiency of four-wave mixing (FWM), a χ(3) nonlinear optical process. We study the effect of slot and waveguide widths, as well as waveguide asymmetry on the two-photon absorption (TPA) figure of merit and the roughness scattering loss. The optimal waveguide core width is shown to be 220nm (symmetric) with a slot width of 120nm, at a fixed waveguide height of 220nm. We also show that state-of-the-art slot waveguides can outperform rib waveguides, especially at high powers, due to the high TPA figure-of-merit.
Vaden, Karl R.
2006-01-01
Communication systems for future NASA interplanetary spacecraft require transmitter power ranging from several hundred watts to kilowatts. Several hybrid junctions are considered as elements within a corporate combining architecture for high power Ka-band space traveling-wave tube amplifiers (TWTAs). This report presents the simulated transmission characteristics of several hybrid junctions designed for a low loss, high power waveguide based power combiner.