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Showing papers on "Beam (structure) published in 2014"


Book
12 Mar 2014
TL;DR: In this paper, the effect of reflectivity of the surface, when a pure, monochromatic laser (6) is used, is remedied by the simultaneous application of a relatively shorter wavelength beam (1).
Abstract: In the laser treatment of a workpiece (9), e.g. for surface hardening, melting, alloying, cladding, welding or cutting, the adverse effect of reflectivity of the surface, when a pure, monochromatic laser (6) is used, is remedied by the simultaneous application of a relatively shorter wavelength beam (1). The two beams (1)(5) may be combined by a beam coupler (4) or may reach the workpiece (9) by separate optical paths (not shown). The shorter wavelength beam (1) improves the coupling efficiency of the higher- powered laser beam (5).

1,539 citations


Journal ArticleDOI
Peter A. R. Ade1, Nabila Aghanim2, C. Armitage-Caplan3, Monique Arnaud4  +273 moreInstitutions (59)
TL;DR: In this article, the authors characterized the effective beams, the effective beam window functions and the associated errors for the Planck High Frequency Instrument (HFI) detectors, including the effect of the optics, detectors, data processing and the scan strategy.
Abstract: This paper characterizes the effective beams, the effective beam window functions and the associated errors for the Planck High Frequency Instrument (HFI) detectors. The effective beam is the angular response including the effect of the optics, detectors, data processing and the scan strategy. The window function is the representation of this beam in the harmonic domain which is required to recover an unbiased measurement of the cosmic microwave background angular power spectrum. The HFI is a scanning instrument and its effective beams are the convolution of: a) the optical response of the telescope and feeds; b) the processing of the time-ordered data and deconvolution of the bolometric and electronic transfer function; and c) the merging of several surveys to produce maps. The time response transfer functions are measured using observations of Jupiter and Saturn and by minimizing survey difference residuals. The scanning beam is the post-deconvolution angular response of the instrument, and is characterized with observations of Mars. The main beam solid angles are determined to better than 0.5% at each HFI frequency band. Observations of Jupiter and Saturn limit near sidelobes (within 5 degrees) to about 0.1% of the total solid angle. Time response residuals remain as long tails in the scanning beams, but contribute less than 0.1% of the total solid angle. The bias and uncertainty in the beam products are estimated using ensembles of simulated planet observations that include the impact of instrumental noise and known systematic effects. The correlation structure of these ensembles is well-described by five errors eigenmodes that are sub-dominant to sample variance and instrumental noise in the harmonic domain. A suite of consistency tests provide confidence that the error model represents a sufficient description of the data. The total error in the effective beam window functions is below 1% at 100 GHz up to multiple l similar to 1500, below 0.5% at 143 and 217 GHz up to l similar to 2000.

1,124 citations


Journal ArticleDOI
TL;DR: In this article, a chiral-lattice-based EMM beam with multiple embedded local resonators is suggested to achieve broadband vibration suppression without sacrificing its loadbearing capacity, and the required unit number of the resonator in each section is quantitatively determined for complete vibration attenuation.

369 citations


Patent
Koichi Akiyama1
01 Aug 2014
TL;DR: In this article, a rotating fluorescent plate has a single fluorescent layer adapted to convert a part or whole of the excitation light beam into a fluorescent light beam, which can be rotated by a motor, continuously along a circular disk.
Abstract: An illumination device includes: a light source device adapted to emit an excitation light beam; and a rotating fluorescent plate having a single fluorescent layer adapted to convert a part or whole of the excitation light beam into a fluorescent light beam. The fluorescent light beam includes two or more colored light beams, and the single fluorescent layer is formed on a circular disk, which can be rotated by a motor, continuously along a circumferential direction of the circular disk.

260 citations


Journal ArticleDOI
TL;DR: In this paper, the authors proposed a new metamaterial beam based on multi-frequency vibration absorbers for broadband vibration absorption, which consists of a uniform isotropic beam and small two-mass spring-mass-damper subsystems at many locations along the beam.

236 citations


Journal ArticleDOI
TL;DR: In this paper, an experimental and an analytical investigation of the behavior of Reinforced Concrete (RC) beams strengthened in flexure by means of different combinations of externally bonded hybrid Glass and Carbon Fiber Reinforced Polymer (GFRP/CFRP) sheets is presented.

215 citations


Journal ArticleDOI
TL;DR: In this article, it was shown that orbital angular momentum is conserved during high-harmonic generation of a beam with an angular-dependant phase Φ = lϕ about the beam axis.
Abstract: A beam with an angular-dependant phase Φ = lϕ about the beam axis carries an orbital angular momentum of lℏ per photon. Such beams are exploited to provide superresolution in microscopy. Creating extreme ultraviolet or soft-x-ray beams with controllable orbital angular momentum is a critical step towards extending superresolution to much higher spatial resolution. We show that orbital angular momentum is conserved during high-harmonic generation. Experimentally, we use a fundamental beam with |l| = 1 and interferometrically determine that the harmonics each have orbital angular momentum equal to their harmonic number. Theoretically, we show how any small value of orbital angular momentum can be coupled to any harmonic in a controlled manner. Our results open a route to microscopy on the molecular, or even submolecular, scale.

208 citations


Journal ArticleDOI
TL;DR: In this article, the stable transfer of gold-coated hollow glass spheres against the power flow of a single inhomogeneously polarized laser beam over tens of centimetres is demonstrated.
Abstract: Laser-based tractor beams move hollow glass particles over tens of centimetres. The laser beam has become an indispensable tool for the controllable manipulation and transport of microscopic objects in biology, physical chemistry and condensed matter physics. In particular, ‘tractor’ laser beams can draw matter towards a laser source and perform, for instance, all-optical remote sampling. Recent advances in lightwave technology have already led to small-scale experimental demonstrations of tractor beams1,2,3,4. However, the realization of long-range tractor beams has not gone beyond the realm of theoretical investigations5,6,7,8,9. Here, we demonstrate the stable transfer of gold-coated hollow glass spheres against the power flow of a single inhomogeneously polarized laser beam over tens of centimetres. Additionally, by varying the polarization state of the beam we can stop the spheres or reverse the direction of their motion at will.

191 citations


Journal ArticleDOI
TL;DR: In this article, it was shown that the divergence angle increases with increasing OAM, thus requiring a larger aperture at the receiving optical system if the efficiency of detection is to be maintained.
Abstract: There is recent interest in the use of light beams carrying orbital angular momentum (OAM) for creating multiple channels within free-space optical communication systems. One limiting issue is that, for a given beam size at the transmitter, the beam divergence angle increases with increasing OAM, thus requiring a larger aperture at the receiving optical system if the efficiency of detection is to be maintained. Confusion exists as to whether this divergence scales linarly with, or with the square root of, the beam's OAM. We clarify how both these scaling laws are valid, depending upon whether it is the radius of the Gaussian beam waist or the rms intensity which is kept constant while varying the OAM.

190 citations


Book ChapterDOI
01 Jan 2014
TL;DR: A new generation of LIDAR sensors equipped with many simultaneous rotating beams at varying angles is spawned, providing at least an order of magnitude more data than single-beam LIDars and enabling new applications in mapping, object detection and recognition, scene understanding, and SLAM.
Abstract: Light Detection and Ranging (LIDAR) sensors have become increasingly common in both industrial and robotic applications. LIDAR sensors are particularly desirable for their direct distance measurements and high accuracy, but traditionally have been configured with only a single rotating beam. However, recent technological progress has spawned a new generation of LIDAR sensors equipped with many simultaneous rotating beams at varying angles, providing at least an order of magnitude more data than single-beam LIDARs and enabling new applications in mapping [6], object detection and recognition [15], scene understanding [16], and SLAM [9].

169 citations


Journal ArticleDOI
TL;DR: In this article, the principles of operation of electro-optical or acousto-optic deflectors and AODs are described and the characteristics, properties and the (dis)advantages of EODs, when compared to mirror-based mechanical de-∆ectors, are discussed.

Journal ArticleDOI
Zhihong Li1, Zhonghua Wu1, Guang Mo1, Xueqing Xing1, Peng Liu1 
TL;DR: In this paper, the authors present the development and current state of a small-angle X-ray scattering station at beamline 1W2A of the Beijing Synchrotron Radiation Facility, China.
Abstract: This article presents the development and current state of a small-angle X-ray scattering station at beamline 1W2A of the Beijing Synchrotron Radiation Facility, China. The source of the beamline is introduced from a 14-pole wiggler. A triangular bending Si(111) crystal is used to horizontally focus the beam and provide a monochromatic X-ray beam (8.052 keV). A bending cylindrical mirror coated with rhodium downstream from the monochromator is used to vertically focus the beam. The X-ray beam is focused on the detector which is fixed at 30 m from the source. The focused beam size (full width at half maximum) is 1.4 × 0.2 mm2 (horizontal × vertical) with a flux of 5.5 × 1011 phs/s at 2.5 GeV and 250 mA. Besides the routine mode of small-angle X-ray scattering, the combination of small- and wide-angle X-ray scattering, grazing incidence small-angle X-ray scattering, and time-resolved small-angle X-ray scattering in sub-second level are also available for the users. Dependent on the measurement requirements,...

Journal ArticleDOI
TL;DR: In this paper, the linear free vibration of nanocomposite beams reinforced by single-walled carbon nanotubes (SWCNTs) is investigated and the virtual strain and kinetic energies of the FG-CNT composite beam are obtained using the classic variational method of Hamilton's principle and then solved by the p-Ritz method.

Journal ArticleDOI
TL;DR: In this paper, a Bernoulli-Euler beam model is proposed to investigate the electromechanical coupling response of piezoelectric nanostructures, in which the effects of surface elasticity, dielectricity and pieziolectricness as well as bulk flexoelectoricity are all taken into consideration.
Abstract: The effects of surface and flexoelectricity have been found in the presence of strong size dependence and should be technically taken into account for nano-scaled dielectric structures. This paper proposes a Bernoulli–Euler beam model to investigate the electromechanical coupling response of piezoelectric nanostructures, in which the effects of surface elasticity, dielectricity and piezoelectricity as well as bulk flexoelectricity are all taken into consideration. The governing equations with non-classical boundary conditions are naturally derived from a variational principle. Then the present beam model is directly applied to solve the static bending problems of cantilever beams. Without considering the residual surface stresses, the bending rigidity can be defined the same as that in classical piezoelectricity theory. The bending rigidity is found to increase for silicon nanowires and decrease for silver nanowires. Also the flexoelectric effect in piezoelectric nanowires has a momentous influence on the bending rigidity. The residual surface stresses which are usually neglected are found to be more important than the surface elasticity for the bending of nanowires. However, this has no influence on the effective electromechanical coupling coefficient. The deflections reveal the significance of the residual surface stresses and the bulk flexoelectric effects. The effective electromechanical coupling coefficient for piezoelectric nanowires is dramatically enhanced, which demonstrates the significant effects of the bulk flexoelectricity and surface piezoelectricity. The effects of surface and flexoelectricity decrease with the increase of the beam thickness, and therefore these effects can be ignored for large-scale structures. This work is very helpful in designing cantilever-beam-based nano-electro-devices.

Journal ArticleDOI
TL;DR: In this paper, the buckling analysis of three microbeam models based on modified couple stress theory is investigated, and a generalized differential quadrature (GDQ) method is employed to solve the governing differential equations.

Journal ArticleDOI
TL;DR: In this paper, the mechanical behavior of shear strength of steel fiber-reinforced concrete beams was analyzed, and the results demonstrated a great contribution from steel fibers to shear-strength of reinforced concrete beams and to reduce crack width.
Abstract: This study analyzed the mechanical behavior of shear strength of steel fiber-reinforced concrete beams. Six beams subjected to shear loading were tested until failure. Additionally, prisms were tested to evaluate fiber contribution to the concrete shear strength. Steel fibers were straight, hook-ended, 35 mm long and aspect ratio equal to 65. Volumetric fractions used were 1.0 and 2.0%. The results demonstrated a great contribution from steel fibers to shear strength of reinforced concrete beams and to reduce crack width, which can reduce the amount of stirrups in reinforced concrete structures. Beam capacity was also evaluated by empirical equations, and it was found that these equations provided a high variability, while some of them have not properly predicted the ultimate shear strength of the steel fiber-reinforced concrete beams.

Journal ArticleDOI
TL;DR: In this article, a size-dependent functionally graded piezoelectric beam model was developed using a variational formulation based on the modified strain gradient theory and Timoshenko beam theory.

Journal ArticleDOI
TL;DR: In this paper, the authors demonstrate that the recently presented iFEM for beam and frame structures is reliable when experimentally measured strains are used as input data, i.e., reconstruction of the displacement field of a structure from surface-measured strains, has relevant implications for the monitoring, control and actuation of smart structures.
Abstract: Shape sensing, i.e., reconstruction of the displacement field of a structure from surface-measured strains, has relevant implications for the monitoring, control and actuation of smart structures. The inverse finite element method (iFEM) is a shape-sensing methodology shown to be fast, accurate and robust. This paper aims to demonstrate that the recently presented iFEM for beam and frame structures is reliable when experimentally measured strains are used as input data.The theoretical framework of the methodology is first reviewed. Timoshenko beam theory is adopted, including stretching, bending, transverse shear and torsion deformation modes. The variational statement and its discretization with C0-continuous inverse elements are briefly recalled. The three-dimensional displacement field of the beam structure is reconstructed under the condition that least-squares compatibility is guaranteed between the measured strains and those interpolated within the inverse elements.The experimental setup is then described. A thin-walled cantilevered beam is subjected to different static and dynamic loads. Measured surface strains are used as input data for shape sensing at first with a single inverse element. For the same test cases, convergence is also investigated using an increasing number of inverse elements. The iFEM-recovered deflections and twist rotations are then compared with those measured experimentally. The accuracy, convergence and robustness of the iFEM with respect to unavoidable measurement errors, due to strain sensor locations, measurement systems and geometry imperfections, are demonstrated for both static and dynamic loadings.

Journal ArticleDOI
TL;DR: A model for a source whose DOC is the superposition of two 1D cosine-Gaussian-correlated Schell-model sources, i.e., possesses rectangular symmetry is proposed, which carries out experimental generation of the proposed beam and measured its focusing properties.
Abstract: Cosine-Gaussian-correlated Schell-model sources whose degree of coherence (DOC) is of circular symmetry have been introduced just recently [Opt. Lett.38, 2578 (2013)]. In this Letter, we propose a model for a source whose DOC is the superposition of two 1D cosine-Gaussian-correlated Schell-model sources, i.e., possesses rectangular symmetry. The novel model sources and beams they generate are termed rectangular cosine-Gaussian Schell-model (RCGSM). The RCGSM beam exhibits unique features on propagation, e.g., its intensity in the far field (or in the focal plane) displays a four-beamlet array profile, being qualitatively different from the ring-shaped profile of the CGSM beam whose DOC is of circular symmetry. Furthermore, we have carried out experimental generation of the proposed beam and measured its focusing properties. Our experimental results are consistent with the theoretical predictions.

Journal ArticleDOI
TL;DR: In this paper, the effects of shape variations of a cantilever beam on its performance as an energy harvester were investigated and a reduced-order model based on a one-mode Galerkin approach was derived.
Abstract: We investigate the effects of shape variations of a cantilever beam on its performance as an energy harvester. The beam is composed of piezoelectric and metallic layers (unimorph design) with a rigid mass attached to its free end. A reduced-order model based on a one-mode Galerkin approach is derived. Solutions for the tip displacement, generated voltage, and harvested power are then obtained. Linear and quadratic shape variations are considered in order to design piezoelectric energy harvesters that can generate energy at low frequencies and maximize the harvested energy. The results show that the fundamental natural frequency and mode shape are strongly affected when the shape of the beam is varied. The influence of the electrical load resistance and the shape parameters at resonance on the system’s performance is discussed. It is determined that for specific resistance values, the quadratic shape can yield up to two times the energy harvested by a rectangular shape.

Journal ArticleDOI
TL;DR: In this Letter a new class of light beam arisen from the symmetrization of the spectral cubic phase of an Airy beam is presented and its features are analyzed and compared to other kinds of autofocusing beams.
Abstract: In this Letter a new class of light beam arisen from the symmetrization of the spectral cubic phase of an Airy beam is presented. The symmetric Airy beam exhibits peculiar features. It propagates at initial stages with a single central lobe that autofocuses and then collapses immediately behind the autofocus. Then, the beam splits into two specular off-axis parabolic lobes like those corresponding to two Airy beams accelerating in opposite directions. Its features are analyzed and compared to other kinds of autofocusing beams; the superposition of two conventional Airy beams having opposite accelerations (in rectangular coordinates) and also to the recently demonstrated circular Airy beam (in cylindrical coordinates). The generation of a symmetric Airy beam is experimentally demonstrated as well. Besides, based on its main features, some possible applications are also discussed.

Journal ArticleDOI
TL;DR: In this paper, a general optical system for synthesis of partially coherent vector beams with a variety of correlation functions was introduced, termed the specially correlated radially polarized (SCRP) beams and examined their free space propagation both theoretically and experimentally.
Abstract: We introduce a general optical system for synthesis of partially coherent vector beams with a variety of correlation functions. In particular we employ it for generation of the family of beams, termed the specially correlated radially polarized (SCRP) beams and examine their free-space propagation both theoretically and experimentally. Our results clearly show that a SCRP beam exhibits unique features on propagation in comparison with those of beams with conventional correlation functions. The technique for modulation of the correlation functions and, hence, the coherence state of a SCRP beam in the source plane leads to efficient control of its intensity distribution and its degree of polarization on propagation, which is of importance in particle trapping and material thermal processing applications.

Journal ArticleDOI
TL;DR: In this article, the Carrera Unified Formulation (CUF) is used to perform free-vibrational analyses of functionally graded (FG) structures, which can be obtained by expanding the unknown displacement variables over the beam section axes by adopting any kind of function The number of the terms in the expansions is a free parameter of the analysis for Taylor-like expansions.
Abstract: The Carrera Unified Formulation (CUF) is used to perform free-vibrational analyses of functionally graded (FG) structures CUF is a hierarchical formulation for obtaining refined structural theories that account for variable kinematic description These theories can be obtained by expanding the unknown displacement variables over the beam section axes by adopting any kind of function The number of the terms in the expansions is a free parameter of the analysis For Taylor-like expansions, the linear case can result in classical beam theories For the first time in the 1D CUF framework, the Finite Element method is used to solve the governing equations of functionally graded beams which are derived in a weak form by means of the Principle of Virtual Displacements These equations are written in terms of f¨undamental nuclei¨ Their forms do not depend on the expansions used Several structures are considered, including a sandwich beam with FG core, laminated beams, thin- and thick-walled boxes as well as sandwich cylinders The results are shown in terms of natural frequencies and compared with those available in existing literature

Journal ArticleDOI
TL;DR: In this article, a new microstructure-dependent sinusoidal beam model for buckling of microbeams using modified strain gradient theory is presented and the equilibrium equations and corresponding boundary conditions in buckling are derived with the minimum total potential energy principle.

Journal ArticleDOI
TL;DR: In this paper, the authors developed a finite element formulation for beams according to the Kirchhoff theory of thin rods, which includes the deformation states of axial tension, torsion and bending.

Journal ArticleDOI
TL;DR: In this paper, the authors present the reinforcement corrosion process and results of experiments on a highly corroded beam subjected to a chloride environment for 26 years so as to assess the residual performance of long-term corrosion-damaged beams.

Journal ArticleDOI
TL;DR: In this paper, the authors deal with the large amplitude vibration, nonlinear bending and thermal postbuckling of functionally graded material (FGM) beams resting on an elastic foundation in thermal environments.

Book
25 Sep 2014
TL;DR: Ion Beam Treatment of Polymers, Second Edition as discussed by the authors presents the results of polymer investigations and technique development in the field of polymer modification by high-energy ion beams, and shows how to use ion beam equipment in the polymer industry, as well as how to produce new polymer materials.
Abstract: Ion Beam Treatment of Polymers, Second Edition presents the results of polymer investigations and technique development in the field of polymer modification by high-energy ion beams. It shows how to use ion beam equipment in the polymer industry, as well as how to use it to produce new polymer materials. The authors, scientists and researchers active in the field, provide analysis and data from their work, and give an overview of related work by others. The authors focus on wetting, adhesion, hardness, chemical activity, environmental stability, biocompatibility, new synthesis methods, and space flight construction. The technologies of material modification by a beam of high energy ions have wide applications in different fields, from microelectronics to medicine. Historically, ion beam treatment of polymers had fewer applications due to high costs of ion beam equipment and low costs of polymer materials. The modern development of new pulse sources with a high current density and wide ion beams increase the effectiveness of ion beam technology for polymers. Collates data from many scientists working in polymer chemistry, physics of ion beam implantation, and in development and production of ion beam equipment Covers industrial and scientific applications of ion beam implanted polymers Integrates physical and chemical aspects of the processes in polymers treated by ion beams

Journal ArticleDOI
TL;DR: In this article, an evaporation model for beam-based additive manufacturing processes, such as selective electron beam or selective laser melting (SEBM/SLM), is presented.
Abstract: Evaporation plays an important role in many technical applications including beam-based additive manufacturing processes, such as selective electron beam or selective laser melting (SEBM/SLM). In this paper, we describe an evaporation model which we employ within the framework of a two-dimensional free surface lattice Boltzmann method. With this method, we solve the hydrodynamics as well as thermodynamics of the molten material taking into account the mass and energy losses due to evaporation and the recoil pressure acting on the melt pool. Validation of the numerical model is performed by measuring maximum melt depths and evaporative losses in samples of pure titanium and Ti–6Al–4V molten by an electron beam. Finally, the model is applied to create processing maps for an SEBM process. The results predict that the penetration depth of the electron beam, which is a function of the acceleration voltage, has a significant influence on evaporation effects.

Journal ArticleDOI
TL;DR: In this article, an extended interaction klystron (EIK) amplifier was demonstrated with a depressed collector, which achieved an efficiency of 17% with an average power of 7.5 kW.
Abstract: A technological breakthrough is embodied in the successful demonstration of an extended interaction klystron (EIK) amplifier, which has produced over 7.5 kW of peak output power at W-band (94 GHz). An efficiency of ${\sim}{17\%}$ has been achieved with a depressed collector. The EIK is driven by a 20-kV, 4-A sheet beam in a permanent magnet solenoid, with 99% beam current transmission from gun to collector. Key features that contribute to the success of this device are: 1) tight beam focusing and correspondingly narrow beam tunnel, which are made possible by the solenoidal focusing and which provide high interaction impedance and high gain per unit length and 2) the incorporation of design elements to stabilize the inherently over-moded circuit. Measured performance agrees well with 3-D particle-in-cell simulations.