Showing papers on "Shell (structure) published in 2009"
TL;DR: The fundamental properties and synthesis methods of core/shell and core/multiple shell structures of II- VI, IV-VI, and III-V semiconductors are discussed.
Abstract: Colloidal core/shell nanocrystals contain at least two semiconductor materials in an onionlike structure. The possibility to tune the basic optical properties of the core nanocrystals, for example, their fluorescence wavelength, quantum yield, and lifetime, by growing an epitaxial-type shell of another semiconductor has fueled significant progress on the chemical synthesis of these systems. In such core/shell nanocrystals, the shell provides a physical barrier between the optically active core and the surrounding medium, thus making the nanocrystals less sensitive to environmental changes, surface chemistry, and photo-oxidation. The shell further provides an efficient passivation of the surface trap states, giving rise to a strongly enhanced fluorescence quantum yield. This effect is a fundamental prerequisite for the use of nanocrystals in applications such as biological labeling and light-emitting devices, which rely on their emission properties. Focusing on recent advances, this Review discusses the fundamental properties and synthesis methods of core/shell and core/multiple shell structures of II-VI, IV-VI, and III-V semiconductors.
1,806 citations
TL;DR: In this article, a nonlinear Kirchhoff-love shell element is developed on the basis of the isogeometric approach, which is discretized by displacement degrees of freedom only.
847 citations
TL;DR: In this article, a generalization of the power-law distribution presented in literature is proposed for the volume fraction of conical shells, where materials are assumed to be isotropic and inhomogeneous through the thickness direction.
475 citations
TL;DR: In this paper, the dynamics of conical, cylindrical shells and annular plates were analyzed using the first-order shear deformation theory (FSDT) and the generalized differential quadrature (GDQ) method.
315 citations
TL;DR: This work investigates 132 binary-alloyed nanoparticle systems using density functional theory (DFT) and systematically explore their segregation energies to determine core-shell preferences, and provides a universal description of core- shell preference via tight-binding theory (band-energy differences) that quantitatively reproduces the DFT segregation energies.
Abstract: Transition-metal alloyed nanoparticles with core−shell features (shell enrichment by one of the metals) are becoming ubiquitous, from (electro-)catalysis to biomedical applications, due to their si...
225 citations
Patent•
26 Feb 2009TL;DR: In orthopedic prosthesis for implantation into a bone of a patient, a non-porous member may be affixed to the porous metal shell as mentioned in this paper, which can be broken at the reduced material cross-section and removed from the porosity.
Abstract: An orthopedic prosthesis for implantation into a bone of a patient includes a porous metal shell adapted to be affixed within the bone. The porous metal shell includes an outer surface adapted to receive bone ingrowth and an inner surface adapted to engage a liner. The porous metal shell is porous from the outer surface to the inner surface. A non-porous member may be affixed to the porous metal shell. The non-porous member may include a piercing member extending from the outer surface, the piercing member adapted to penetrate the bone in an implanted position. The non-porous member may include spikes or fins. In one example, the piercing member may define a reduced material cross section at an interface with the outer surface of the porous metal shell. The piercing member may be adapted to be broken at the reduced material cross section and removed from the porous metal shell.
220 citations
TL;DR: In this paper, the authors study the dynamic behavior of functionally graded parabolic and circular panels and shells of revolution using First-order Shear Deformation Theory (FSDT) to study these moderately thick structural elements.
Abstract: The aim of this paper is to study the dynamic behaviour of functionally graded parabolic and circular panels and shells of revolution. The First-order Shear Deformation Theory (FSDT) is used to study these moderately thick structural elements. The treatment is developed within the theory of linear elasticity, when the materials are assumed to be isotropic and inhomogeneous through the thickness direction. The two-constituent functionally graded shell consists of ceramic and metal that are graded through the thickness, from one surface of the shell to the other. Two different power-law distributions are considered for the ceramic volume fraction. For the first power-law distribution, the bottom surface of the structure is ceramic rich, whereas the top surface is metal rich and on the contrary for the second one.
203 citations
TL;DR: In this article, the design problem of maximizing the buckling load factor of laminated multi-material composite shell structures is investigated using the so-called Discrete Material Optimization (DMO) approach.
195 citations
TL;DR: In this article, a generalization of the power-law distribution presented in literature is proposed for the ceramic volume fraction, and the governing equations of motion are expressed as functions of five kinematic parameters.
Abstract: Basing on the First-order Shear Deformation Theory (FSDT), this paper focuses on the dynamic behaviour of moderately thick functionally graded parabolic panels and shells of revolution. A generalization of the power-law distribution presented in literature is proposed. Two different four-parameter power-law distributions are considered for the ceramic volume fraction. Some symmetric and asymmetric material profiles through the functionally graded shell thickness are illustrated by varying the four parameters of power-law distributions. The governing equations of motion are expressed as functions of five kinematic parameters. For the discretization of the system equations the Generalized Differential Quadrature (GDQ) method has been used. Numerical results concerning four types of parabolic shell structures illustrate the influence of the parameters of the power-law distribution on the mechanical behaviour of shell structures considered.
178 citations
Patent•
11 Feb 2009
TL;DR: In this article, the utility model provides a multi-level automobile shell, and relates to the technical field of the automobile, which comprises a car main body, wherein, a pattern area is arranged on the shell of the car, and the pattern area comprises a shell; the shell is covered with a pattern layer; the pattern layer is provided with a fluorescent powder layer; a transparent resin layer is arranged, and a paint layer of the shell can be provided with patterns, so that the car has beautiful view, and has the fluorescent effect.
Abstract: The utility model provides a multi-level automobile shell, and relates to the technical field of the automobile, which comprises a car main body, wherein, a pattern area is arranged on the shell of the car main body; the pattern area comprises a shell; the shell is covered with a pattern layer; the pattern layer is provided with a fluorescent powder layer; a transparent resin layer is arranged on the fluorescent powder layer; a paint layer of the shell of the car can be provided with patterns, so that the car has beautiful view, and has the fluorescent effect, and can reduce the safety problem when the car is driving in the night without the streetlamp.
174 citations
TL;DR: In this paper, a triangular shell element for the simulation of textile composite reinforcements forming is proposed, which is made up of unit woven cells and the internal virtual works are added on all woven cells of the element.
Abstract: A triangular shell element for the simulation of textile composite reinforcements forming is proposed. This element is made up of unit woven cells. The internal virtual works are added on all woven cells of the element. They depend on tensions, in-plane shear and bending moments that are directly those given by the experimental tests that are specific to textile composite reinforcement. The element has only displacement degrees of freedom; the bending curvatures are obtained from the displacement of the neighbouring elements. A set of example shows the efficiency of the approach and the relative roles of the tensile, in-plane shear and bending rigidities. Especially their influence on the appearance and the development of wrinkles in draping and forming tests is analysed. Copyright © 2009 John Wiley & Sons, Ltd.
TL;DR: In this article, the design progress in a compact low aspect ratio (low A) DEMO reactor, "SlimCS", and its design issues are reported The design study focused mainly on the torus configuration including the blanket, divertor, materials and maintenance scheme.
Abstract: The design progress in a compact low aspect ratio (low A) DEMO reactor, 'SlimCS', and its design issues are reported The design study focused mainly on the torus configuration including the blanket, divertor, materials and maintenance scheme For continuity with the Japanese ITER-TBM, the blanket is based on a water-cooled solid breeder blanket For vertical stability of the elongated plasma and high beta access, the blanket is segmented into replaceable and permanent blankets and a sector-wide conducting shell is arranged inbetween these blankets A numerical calculation indicates that fuel self-sufficiency can be satisfied when the blanket interior is ideally fabricated An allowable heat load to the divertor plate should be 8 MW m−2 or lower, which can be a critical constraint for determining a handling power of DEMO
TL;DR: In this paper, a thermally-sponsive nanocomposites comprising a gold nanoparticle core and a poly(N-isopropylacrylamide) (pNIPAM) shell are synthesized by grafting the gold nanoparticles surface with polystyrene, which allows the coating of an inorganic core with an organic shell.
Abstract: Thermoresponsive nanocomposites comprising a gold nanoparticle core and a poly(N-isopropylacrylamide) (pNIPAM) shell are synthesized by grafting the gold nanoparticle surface with polystyrene, which allows the coating of an inorganic core with an organic shell. Through careful control of the experimental conditions, the pNIPAM shell cross-linking density can be varied, and in turn its porosity and stiffness, as well as shell thickness from a few to a few hundred nanometers is tuned. The characterization of these core–shell systems is carried out by photon-correlation spectroscopy, transmission electron microscopy, and atomic force microscopy. Additionally, the porous pNIPAM shells are found to modulate the catalytic activity, which is demonstrated through the seeded growth of gold cores, either retaining the initial spherical shape or developing a branched morphology. The nanocomposites also present thermally modulated optical properties because of temperature-induced local changes of the refractive index surrounding the gold cores.
TL;DR: In this article, a reduced integration eight-node solid-shell finite element with the enhanced assumed strain (EAS) concept based on the Hu-Washizu variational principle requires only one EAS degree-of-freedom to cure volumetric and Poisson thickness locking.
Abstract: In this paper a new reduced integration eight-node solid-shell finite element is presented. The enhanced assumed strain (EAS) concept based on the Hu-Washizu variational principle requires only one EAS degree-of-freedom to cure volumetric and Poisson thickness locking. One key point of the derivation is the Taylor expansion of the inverse Jacobian with respect to the element center, which closely approximates the element shape and allows us to implement the assumed natural strain (ANS) concept to eliminate the curvature thickness and the transverse shear locking. The second crucial point is a combined Taylor expansion of the compatible strain with respect to the center of the element and the normal through the element center leading to an efficient and locking-free hourglass stabilization without rank deficiency. Hence, the element requires only a single integration point in the shell plane and at least two integration points in thickness direction. The formulation fulfills both the membrane and the bending patch test exactly, which has, to the authors' knowledge, not yet been achieved for reduced integration eight-node solid-shell elements in the literature. Owing to the three-dimensional modeling of the structure, fully three-dimensional matenal models can be implemented without additional assumptions.
TL;DR: The results demonstrate that one-dimensional metal oxide core-shell nanostructures whose shell thickness is smaller than the Debye length are very promising materials for fabricating gas sensors with good performances.
Abstract: ?-Fe2O3/SnO2 core?shell nanorods are synthesized via a three-step process. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses reveal that their diameters and lengths are respectively in the ranges 35?120?nm and 0.35?1.2??m, and the thickness of the shell composed of 3.5?nm SnO2 nanoparticles is about 10?nm. The core?shell nanostructures exhibit a dramatic improvement in ethanol sensing characteristics compared to pure ?-Fe2O3 nanorods. The sensor response is up to 19.6 under 10?ppm ethanol exposure at 220??C. Both the response time and the recovery time of the core?shell structures are less than 30?s. Based on the space?charge layer model and semiconductor heterojunction theory, the small thickness of the SnO2 shell and the formation of heterojunctions contribute to the enhanced ethanol sensing characteristics. Our results demonstrate that one-dimensional metal oxide core?shell nanostructures whose shell thickness is smaller than the Debye length are very promising materials for fabricating gas sensors with good performances.
TL;DR: In this article, closed-form expressions for approximating the influence of single or multiple holes on the critical elastic buckling stress of plates in bending or compression are developed, validated and summarized.
Abstract: Closed-form expressions for approximating the influence of single or multiple holes on the critical elastic buckling stress of plates in bending or compression are developed, validated and summarized. The expressions are applicable to plates simply supported on 4 sides and plates simply supported on 3 sides, commonly called stiffened and unstiffened elements in design. The expressions serve as a convenient alternative to shell finite element eigen-buckling analysis, which requires commercial software not typically accessible to the engineering design community. The forms of the expressions are founded on classical plate stability approximations, and are developed and validated with parametric studies employing shell finite elements. The finite element parametric studies demonstrate that holes may create unique buckling modes, and can either decrease or increase a plate's critical elastic buckling stress depending on the hole geometry and spacing. The validated closed-form expressions and their associated limits are intended to be general enough to accommodate the range of hole shapes, locations, and spacings common in engineering practice, while at the same time also defining regimes where explicit use of shell finite element analyses is still needed for adequate accuracy.
TL;DR: Values of tensile strength, compressive strength, bending strength, hardness and modulus of elasticity are reported for the shell material of various species of bivalve, gastropod and cephalopod mollusc.
Abstract: Values of tensile strength, compressive strength, bending strength, hardness and modulus of elasticity are reported for the shell material of various species of bivalve, gastropod and cephalopod mollusc. Nacre is the strongest structural type, but crossed lamellar structure is the hardest. Possible selective reasons for these differences are discussed but no firm conclusions are drawn.
TL;DR: In this paper, the elastic buckling of stiffened cylindrical shells by rings and stringers made of functionally graded materials subjected to axial compression loading was studied and the results showed that the inhomogeneity parameter and geometry of shell significantly affect the critical buckling loads.
TL;DR: In this article, the authors present a method to reduce the scattering from arbitrary objects by surrounding them with shells composed of several layers of homogeneous anisotropic materials, the starting point of which is a discretized approximation of a coordinate transformation cloaking shell.
Abstract: We present a method to reduce the scattering from arbitrary objects by surrounding them with shells composed of several layers of homogeneous anisotropic materials An optimization procedure is used to find the material parameters for each layer, the starting point of which is a discretized approximation of a coordinate transformation cloaking shell We show that an optimized, three-layer shell can reduce the maximum scattering of an object by as much as $15\phantom{\rule{03em}{0ex}}\mathrm{dB}$ more than a 100-layer realization of a coordinate transformation cloaking shell Moreover, using an optimization procedure can yield high-performance cloaking shell solutions that also meet external constraints, such as the maximum value of permittivity or permeability This design approach can substantially simplify the fabrication of moderate-size cloaking shells
Patent•
04 Feb 2009
TL;DR: In this article, the authors proposed a utility model for a coaxial cable connector, which consists of a shell body composed of a front and a rear part, wherein a junk ring is arranged on the front section of the shell body, a locking retainer ring is placed on the rear section of shell body and the outer cone of the rear end of the junk ring was provided with a plurality of outer protrusions.
Abstract: The utility model relates to a coaxial cable connector, which belongs to a microwave communication device. The coaxial cable connector comprises a shell body which is composed of a front and a rear parts, wherein a junk ring is arranged on the front section of the shell body, a locking retainer ring is arranged on the rear section of the shell body, the outer cone of the rear end of the junk ring is provided with a plurality of outer protrusions, and the inner cone of the front end of the locking retainer ring is provided with a plurality of inner protrusions. The utility model has the advantages that the actual contact area that the connector is electrically connected with the cable can be improved, and the reliability of the connection is good.
TL;DR: In this paper, the authors derived the surface stresses at the surface of a satellite from the gravitational potential of the satellite's parent planet, assuming that the satellite is fully differentiated into a silicate core, a global subsurface ocean, and a decoupled, viscoelastic lithospheric shell.
TL;DR: In this article, the static response and free vibration of metal and ceramic functionally graded shells are analyzed using the element-free kp-Ritz method, where the material properties are assumed to vary continuously along the depth direction.
TL;DR: In this paper, the authors investigate the distribution patterns of stress in the rock surrounding a fully mechanized top-coal caving (FMTC) face and reveal the mechanical nature of the top coal of an FMTC face acting as a “cushion.
TL;DR: In this paper, a method to synthesize Fe3O4 core/Au shell submicrometer structures with very rough surfaces on the nanoscale is reported, which is used in the adsorption of 4-aminothiophenol and as a substrate for detection by surface enhanced Raman spectroscopy.
Abstract: A method to synthesize Fe3O4 core/Au shell submicrometer structures with very rough surfaces on the nanoscale is reported. The Fe3O4 particles were first modified with uniform polymers through the layer-by-layer technique and then adsorbed a lot of gold nanoseeds for further Au shell formation. The shell was composed of a large number of irregular nanoscale Au particles arranged randomly, and there were well-defined boundaries between these Au nanoparticles. The Fe3O4 core/Au shell particles showed strong plasmon resonance absorption in the near-infrared range, and can be separated quickly from solution by an external magnet. This kind of very rough Fe3O4 core/Au shell multicomponent was used in the adsorption of 4-aminothiophenol and as a substrate for detection by surface-enhanced Raman spectroscopy.
TL;DR: An ultra-fast fabrication of large-scale colloidal PCs via spray coating was demonstrated, and the latex spheres with hydrophobic core and hydrophilic shell resulted in strong hydrogen bonding interaction among latex spheres, which boosted latex arrangement during the spray procedure.
Abstract: An ultra-fast fabrication of large-scale colloidal PCs via spray coating was demonstrated. The latex spheres with hydrophobic core and hydrophilic shell were designed, and the latex shell with abundant COOH groups resulted in strong hydrogen bonding interaction among latex spheres, which boosted latex arrangement during the spray procedure. The resultant samples with area of 7 x 12 cm 2 were easily fabricated within 1 min on different substrates. This ultra-fast fabrication procedure would be of great importance for the practical application of PCs for optic devices and functional coatings.
TL;DR: In this article, the authors investigated the linear and nonlinear dynamic responses of three cylindrical shell structures subjected to underwater small charge explosions in a 4.m×4.m.
TL;DR: In this article, the growth of III-V nanowires from metal seed particles is described in an analytical manner within the framework of a material conservation model, where direct impingement of growth species on the particle, coupled to their diffusion from the sidewall and the substrate surface, are considered in the derivation of expressions for the time evolution of both axial and radial growths.
Abstract: The growth of III–V nanowires from metal seed particles is described in an analytical manner within the framework of a material conservation model. Direct impingement of growth species on the particle, coupled to their diffusion from the sidewall and the substrate surface, are considered in the derivation of expressions for the time evolution of both axial and radial growths. Two regimes are distinguished: the structure originally grows in a purely axial manner until its length exceeds the diffusion length of adatoms incoming from the substrate, at which point sidewall nucleation is triggered, resulting in a shell expanding radially in the lower part of the wire. Factors that take into account the nonunity probability of inclusion of group III adatoms in the axially growing crystal are introduced. Moreover, a step-mediated growth is included to describe the axial evolution of the shell. The numerical values of the various parameters were assessed by fitting the model to experimental data on the morphology evolution of molecular-beam-epitaxy-grown GaAs and InAs nanowires.
TL;DR: A nanosized heterometallic cluster containing 60 La(III) and 76 Ni(II) ions, which are arranged into a four-shell, nest-like framework structure, was obtained by the hydrolytic reaction of the mixed La(NO(3)(3)-Ni(3))(2) system using iminodiacetate as an ancillary ligand to control the Hydrolysis.
TL;DR: In this article, a core/shell/shell structure consisting of CdTe core/CdS shell/ZnO shell was fabricated with a high lattice mismatch between CdS and ZnO.
Abstract: New quantum dots (QDs) were fabricated with a core/shell/shell structure consisting of CdTe core/CdS shell/ZnO shell. Despite the high lattice mismatch between CdS and ZnO, a ZnO shell was successf...
TL;DR: An easy assembling-disassembling co-axial capillaries microfluidic device was built up for the production of double droplets and uniform and predictable non-spherical polymer objects were also prepared without adding shape-formation procedures in the experimental device.
Abstract: An easy assembling–disassembling co-axial capillaries microfluidic device was built up for the production of double droplets. Uniform polymer core-polymer shell particles were synthesized by polymerizing the two immiscible monomer phases composing the double droplet. Thus poly(acrylamide) core-poly(tri(propylene glycol) diacrylate) shell particles with controlled core diameter and shell thickness were simply obtained by adjusting operating parameters. An empirical law was extracted from experiments to predict core and shell sizes. Additionally uniform and predictable non-spherical polymer objects were also prepared without adding shape-formation procedures in the experimental device. An empirical equation for describing the lengths of rod-like polymer particles is also presented.