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Large-area crack-free 2D and 3D WO 3 inverse opal (IO) films, using a wide range of sizes of sacrificial PS spheres as colloidal crystal template, were fabricated by “dynamic hard template infiltration strategy”. First a dynamic PS opal film was formed floating on the surface of water followed by infiltration of a preformed WO 3 sol underneath the PS opal film. The resultant PS/WO 3 opal composite film was then deposited on various types of substrates (rigid and flexible) and 2D WO 3 IO films were obtained following the removal of the PS template by chemical method. Based on this strategy, multiple layer WO 3 IOs were fabricated through a layer by layer route. The WO 3 IO films deposited on indium tin oxide coated conductive (ITO) substrates were used as active electrode in the fabrication of electrochromic devices, demonstrating their advanced properties for electrochromic application.

Two-dimensional (2D) metal–organic frameworks (MOFs) have emerged as intriguing 2D materials because of their specific features of 2D morphology and designable skeletons, which have elicited great interest in environment remediation. In this work, 2D MOF nanosheets are fabricated via a mixed-solvent solvothermal method, and a regulation strategy of metal inorganic clusters on MOFs is used to construct two different 2D MOFs with monometallic and bimetallic coordination, that is, Ni-MOF and Ni/Cd-MOF. Binary metal coordination renders more crystal defects and vacancies in the framework; thus, compared to monometallic Ni-MOF, bimetallic Ni/Cd-MOF exhibits fewer layers (4∼5 layers), higher specific surface area, larger pore size, and higher surface electronegativity, which leads to its excellent adsorption removal for Pb2+, with higher adsorption rate and affinity, and superior adsorption capacity (950.61 mg/g, almost twice as high as that of monometallic Ni-MOF). Besides, the adsorption mechanism further confirmed that the carboxyl groups (−COO−) from organic linker on 2D MOFs serve as the main binding sites for Pb2+ coordination, and bimetallic Ni/Cd-MOF has more active −COO− sites for Pb2+ capture. Thus, the bimetallic Ni/Cd-MOF regulated by heterogeneous metal atoms shows promising application for highly efficient adsorption of heavy metal ions.

This is the peer reviewed version of the following article: Zheng, X., Mofarah, S. S., Cazorla, C., Daiyan, R., Esmailpour, A. A., Scott, J., Yao, Y., Lim, S., Wong, V., Chen, E. Y., Arandiyan, H., Koshy, P., Sorrell, C. C., Decoupling the Impacts of Engineering Defects and Band Gap Alignment Mechanism on the Catalytic Performance of Holey 2D CeO2−x-Based Heterojunctions. Adv. Funct. Mater. 2021, 31, 2103171, which has been published in final form at https://doi.org/10.1002/adfm.202103171. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited. Critical catalysis studies often lack elucidation of the mechanistic role of defect equilibria in solid solubility and charge compensation. This approach is applied to interpret the physicochemical properties and catalytic performance of a free-standing 2D–3D CeO2-x scaffold, which is comprised of holey 2D nanosheets, and its heterojunctions with MoO3-x and RuO2. The band gap alignment and structural defects are engineered using density functional theory (DFT) simulations and atomic characterization. Further, the heterojunctions are used in hydrogen evolution reaction (HER) and catalytic ozonation applications, and the impacts of the metal oxide heteroatoms are analyzed. A key outcome is that the principal regulator of the ozonation performance is not oxygen vacancies but the concentration of Ce3+ and Ce vacancies. Cation vacancy defects are measured to be as high as 8.1 at% for Ru-CeO2-x. The homogeneous distribution of chemisorbed, Mo-oxide, heterojunction nanoparticles on the CeO2-x holey nanosheets facilitates intervalence charge transfer, resulting in the dominant effect and resultant ˜50% decrease in overpotential for HER. The heterojunctions are tested for aqueous-catalytic ozonation of salicylic acid, revealing excellent catalytic performance from Mo doping despite the adverse impact of Ce vacancies. The present study highlights the use of defect engineering to leverage experimental and DFT results for band alignment.

The development and utilization of photocatalysts to realize water-splitting without any external bias or sacrificial agents has received the limelight. As a novel two-dimensional layered material, metal phosphorus trichalcogenides (MPTs) cause wide research interest, presently. However, the growth of ultrathin two-dimensional MPT crystals is a great challenge to hinder their application. Here, we initially grow few-atomic layered nickel phosphorus trisulfide (NiPS3) as promising photocatalyst for hydrogen evolution. The as-prepared NiPS3 hexagonal nanosheet, as thin as few atomic layers (≤ 3.5 nm), has lateral size of larger than 15 µm. These ultrathin NiPS3 crystals can directly generate hydrogen gas from pure water without any sacrificial agents under sunlight. With ultraviolet photoelectron spectrometer and electrochemical impedance spectroscopy, we show that the attractive photocatalytic activity of the ultrathin NiPS3 crystals arise from their appropriate positions of the band edges. This discovery is expected to make a contribution to develop next generation solar-fuel conversion catalysts for H2 production.

Objectives This study was evaluated the marginal microleakage of two different adhesive systems before and after aging with two different dye penetration techniques. Materials and Methods Class V cavities were prepared on the buccal and lingual surfaces of 48 human molars. Clearfil SE Bond and Single Bond (self-etching and etch-and-rinse systems, respectively) were applied, each to half of the prepared cavities, which were restored with composite resin. Half of the specimens in each group underwent 10,000 cycles of thermocycling. Microleakage was evaluated using two dimensional (2D) and three dimensional (3D) dye penetration techniques separately for each half of each specimen. Data were analyzed with SPSS 11.5 (SPSS Inc.), using the Kruskal-Wallis and Mann-Whitney U tests (α = 0.05). Results The difference between the 2D and 3D microleakage evaluation techniques was significant at the occlusal margins of Single bond groups (p = 0.002). The differences between 2D and 3D microleakage evaluation techniques were significant at both the occlusal and cervical margins of Clearfil SE Bond groups (p = 0.017 and p = 0.002, respectively). The difference between the 2D and 3D techniques was significant at the occlusal margins of non-aged groups (p = 0.003). The difference between these two techniques was significant at the occlusal margins of the aged groups (p = 0.001). The Mann-Whitney test showed significant differences between the two techniques only at the occlusal margins in all specimens. Conclusions Under the limitations of the present study, it can be concluded that the 3D technique has the capacity to detect occlusal microleakage more precisely than the 2D technique.

CONSPECTUS: Two-dimensional (2D) crystals derived from transition metal dichalcogenides (TMDs) are intriguing materials that offer a unique platform to study fundamental physical phenomena as well as to explore development of novel devices. Semiconducting group 6 TMDs such as MoS2 and WSe2 are known for their large optical absorption coefficient and their potential for high efficiency photovoltaics and photodetectors. Monolayer sheets of these compounds are flexible, stretchable, and soft semiconductors with a direct band gap in contrast to their well-known bulk crystals that are rigid and hard indirect gap semiconductors. Recent intense research has been motivated by the distinct electrical, optical, and mechanical properties of these TMD crystals in the ultimate thickness regime. As a semiconductor with a band gap in the visible to near-IR frequencies, these 2D MX2 materials (M = Mo, W; X = S, Se) exhibit distinct excitonic absorption and emission features. In this Account, we discuss how optical spectroscopy of these materials allows investigation of their electronic properties and the relaxation dynamics of excitons. We first discuss the basic electronic structure of 2D TMDs highlighting the key features of the dispersion relation. With the help of theoretical calculations, we further discuss how photoluminescence energy of direct and indirect excitons provide a guide to understanding the evolution of the electronic structure as a function of the number of layers. We also highlight the behavior of the two competing conduction valleys and their role in the optical processes. Intercalation of group 6 TMDs by alkali metals results in the structural phase transformation with corresponding semiconductor-to-metal transition. Monolayer TMDs obtained by intercalation-assisted exfoliation retains the metastable metallic phase. Mild annealing, however, destabilizes the metastable phase and gradually restores the original semiconducting phase. Interestingly, the semiconducting 2H phase, metallic 1T phase, and a charge-density-wave-like 1T' phase can coexist within a single crystalline monolayer sheet. We further discuss the electronic properties of the restacked films of chemically exfoliated MoS2. Finally, we focus on the strong optical absorption and related exciton relaxation in monolayer and bilayer MX2. Monolayer MX2 absorbs as much as 30% of incident photons in the blue region of the visible light despite being atomically thin. This giant absorption is attributed to nesting of the conduction and valence bands, which leads to diversion of optical conductivity. We describe how the relaxation pathway of excitons depends strongly on the excitation energy. Excitation at the band nesting region is of unique significance because it leads to relaxation of electrons and holes with opposite momentum and spontaneous formation of indirect excitons., G.E. acknowledges Singapore National Research Foundation for funding the research under NRF Research Fellowship (NRF- NRFF2011-02). G.E. also thanks the Graphene Research Centre at the National University of Singapore for funding support. R.M.R is thankful for the financial support by FEDER through the COMPETE Program, by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Project PEST-C/FIS/UI607/2011 and Grant Nr.SFRH/BSAB/1249/2012, and by the EC under Graphene Flagship (contract no. CNECT-ICT-604391)., FEDER, COMPETE, Graphene Flagship

Semiconductors are ubiquitous gain media for coherent light sources. Solution-processed three-dimensional (3D) halide perovskites (e.g., CH3NH3PbI3) with their outstanding room temperature optical gain properties are the latest members of this family. Their two-dimensional (2D) layered perovskite counterparts with natural multiple quantum well structures exhibit strong light–matter interactions and intense excitonic luminescence. However, despite such promising traits, there have been no reports on room temperature optical gain in 2D layered perovskites. Herein, we reveal the challenges towards achieving amplified spontaneous emission (ASE) in the archetypal (C6H5C2H4NH3)2PbI4 (or PEPI) system. Temperature-dependent transient spectroscopy uncovers the dominant free exciton trapping and bound biexciton formation pathways that compete effectively with biexcitonic gain. Phenomenological rate equation modeling predicts a large biexciton ASE threshold of ∼1.4 mJ cm−2, which is beyond the damage threshold of these materials. Importantly, these findings would rationalize the difficulties in achieving optical gain in 2D perovskites and provide new insights and suggestions for overcoming these challenges. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) ASTAR (Agency for Sci., Tech. and Research, S’pore) Published version

A finite-volume-based incompressible flow algorithm on Cartesian grid is presented for the simulation of evaporation phenomena in a falling liquid film under low wall superheat conditions. The model employs the PLIC-VOF method to capture the free surface evolution, and the continuum surface force (CSF) approximation to emulate the effects of interfacial tension. The phase change process is represented through a source term in the interfacial cells, which is evaluated from the normal temperature gradients on either side of the interface. In order to evaluate these discontinuous temperature gradients across the interface accurately, a simple and efficient ghost fluid method has been implemented, which properly takes into account the dynamic evolution of the interface. The overall numerical model, including the phase change algorithm, has been validated against standard benchmark analytical results. Finally, the model is used to simulate the evaporating flow of a 2-D laminar, developing film falling over an inclined plane surface, subjected to constant wall heat flux. The results thus obtained, clearly illustrate the significance of inertial effects in the developing region of the falling film, which are generally neglected in the available analytical models. It is also observed, that the evaporation of fluid commences only after the growing thermal boundary layer reaches the interface, and the length of the nonevaporating section reduces with the increase in wall heat flux value. Copyright � Taylor & Francis Group, LLC.

We report on a two-dimensional highly ordered self-assembled monolayer (SAM) directly grown on a bare polymer surface. Semiconducting SAMs are utilized in field-effect transistors and combined into integrated circuits as 4-bit code generators. The driving force to form highly ordered SAMs is packing of the liquid crystalline molecules caused by the interactions between the linear alkane moieties and the π-π stacking of the conjugated thiophene units. The fully functional circuits demonstrate long-range order over large areas, which can be regarded as the start of flexible monolayer electronics. © 2010 American Chemical Society.

This paper discusses the results of an experimental and numerical study of fluid flow and heat transfer in an enclosure where multiple heaters are arranged in a staggered fashion. Experiments were carried out for Reynolds numbers, in the range 1800�?�Re�?�4500 and Grashof numbers in the range 2.5�נ104�?�Gr�?�3�נ105. Numerical simulations were carried out for two dimensional, steady, incompressible turbulent flow and the results of the numerical study are compared with the experimental results. The temperature distribution gives an insight into the power management among the heaters, so that the "coolest" heater can be loaded most to maximize the total heat dissipation, for a prescribed temperature excess, for all the heaters. Two methods are used to achieve the target temperature for all heaters, namely (i) trial and error method and (ii) the response surface method. The latter method was adopted, to simultaneously maximize the heat input and minimize the�temperature deviation from the target temperature, by employing a composite objective function. The numerically obtained optimal solution was finally verified by carrying out experiments. The method of response surface was found to be effective in optimizing the total heat transfer for a given target temperature. � 2009 Elsevier Masson SAS. All rights reserved.

This Part 2 paper presents results of comparative experimental study of progressive damage in 2D and 3D woven glass/epoxy composites under in-plane tensile loading. As Part 1, this Part 2 work is focused on the comparison of in-plane tensile properties of two non-crimp single-ply 3D orthogonal weave E-glass fibre composites on one side and a laminate reinforced with four plies of E-glass plain weave on the other. The damage investigation methodology combines mechanical testing with acoustic emission registration (that provides damage initiation thresholds), progressive cracks observation on transparent samples, full-field surface strain mapping and cracks observation on micrographs, altogether enabling for a thorough characterisation of the local micro- and meso-damage modes of the studied composites. The obtained results demonstrate that the non-crimp 3D orthogonal woven composites have significantly higher in-plane strengths, failure strains and damage initiation thresholds than their 2D woven laminated counterpart. The growth of transverse cracks in the yarns of 3D composites is delayed, and they are less prone to a yarn-matrix interfacial crack formation and propagation. Delaminations developing between the plies of plain weave fabric in the laminate at certain load level never appear in the 3D woven single-ply composites. (C) 2009 Elsevier Ltd. All rights reserved. East-European PhD grant of K.U. Leuven Research Council (D.S. Ivanov) Department MTM

Natural convection in a two-dimensional square cavity containing hydrodynamically and thermally anisotropic porous medium with internal heat generation is analyzed numerically by generalized non-Darcy approach. The properties considered for the study are permeability ratio (K *), inclination of the principal axes (?), ratio of Forchheimer constants (F *) and thermal conductivity ratio (k *). Results are presented in terms of isotherms, streamlines and maximum temperature in the cavity to understand the flow physics. It is observed that the anisotropic properties have significant influence on the flow behaviour and heat transfer. A correlation for maximum temperature in the cavity for a wide range of parameters (10 7 ? Ra ? 10 8, 10 -6 ? Da ? 10 -3, 0� ? ? ? 90�, 1 ? F * ? 100, 0.1 ? K * ? 10 and 0.1 ? k * ? 10) is developed. � 2008 Elsevier Ltd. All rights reserved.

Scattering from and propagation over rough-terrain profiles, as well as reentrant surfaces are investigated using an integral equation (IE)-based spectrally accelerated biconjugate gradient stabilized (SA-BiCGSTAB) method, with a storage requirement and a computational cost of O(N) per iteration, where N is the surface unknowns in the discretized IE. Numerical results in the form of current and path loss are presented and compared with previously published as well as measured results in order to assess the accuracy and efficiency of this method. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 158–162, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20930

We show that the study of conductivity nonlinearity gives a possibility to determine the condition when the diffusion conductivity changes to the hopping one with increasing disorder. It is experimentally shown that the conductivity of single quantum well GaAs/InGaAs/GaAs heterostructures behaves like diffusive one down to value of order $10^{-2}e^2/h$., Comment: 4 pages, 2 figures

Analyses of rough surface contact sometimes study the two-dimensional problem to avoid some of the difficulties of three-dimensional contacts, or to reduce the size of the calculations in numerical work. But two-dimensional elastic contacts introduce their own difficulties. The mean real contact pressures will be much lower than in three dimensions, and will depend strongly on the thickness of the ‘slab’ used to represent the elastic half-space.

The report investigates the effect of quenching rate on the structure, lithium ion dynamics, and crystallization kinetics of mol% 60Li 2O-40P2O5 glass. Quenching rate of the order of 105 K s-1 has been achieved using a twin-roller rapid quenching setup. Raman and FT-IR studies reveal that the rapidly quenched glass is more disordered with a reduced amount of pyrophosphate structural units (P2O74-) in the glass matrix as compared with the conventionally quenched glass. Non-isothermal differential scanning calorimetry brings out that the rapidly quenched glass undergoes three-phase crystallization while the conventionally quenched glass depicted predominantly single-phase crystallization. The phases are identified as lithium metaphosphate (LiPO3), pyrophosphate (Li4P2O7), and orthophosphate (Li3PO4). The activation energy for crystallization for the major phase Li4P2O7 calculated using thermoanalytical methods turns out to be 287 kJ mol -1. The above structural differences between the rapidly and conventionally quenched glasses result in superior conduction characteristics for the rapidly quenched glass depicting ionic conductivity of 1.0 � 10-6 S cm-1 at 343 K with an activation energy of 0.63 eV for lithium ion motion. Microstructural studies on the glass ceramics divulge surface, 2D, and 3D crystal growth mechanism for lithium meta-, pyro-, and ortho-phosphate phases, respectively. � 2013 Springer Science+Business Media New York.

Date of Conference: 8-12 Sept. 2013 Conventional plasmonic structures provide field enhancement in the plane. The proposed nanoplasmonic three-dimensional surfaces, with unity coverage in the plan-view, enable surface-normal enhancement and achieve 7.2-fold stronger maximum field enhancement compared to the two-dimensional counterparts. © 2013 IEEE.

Fine-tuning nanocatalysts to enhance their catalytic activity and durability is crucial to commercialize proton exchange membrane fuel cells. The structural ordering and time evolution of ordered Pt3Fe2 intermetallic core-shell nanocatalysts for the oxygen reduction reaction that exhibit increased mass activity (228%) and an enhanced catalytic activity (155%) compared to Pt/C has been quantified using aberration-corrected scanning transmission electron microscopy. These catalysts were found to exhibit a static core-dynamic shell regime wherein, despite treating over 10 000 cycles, there is negligible decrease (9%) in catalytic activity and the ordered Pt 3Fe2 core remained virtually intact while the Pt shell suffered a continuous enrichment. The existence of this regime was further confirmed by X-ray diffraction and the compositional analyses using energy-dispersive spectroscopy. With atomic-scale two-dimensional (2-D) surface relaxation mapping, we demonstrate that the Pt atoms on the surface are slightly relaxed with respect to bulk. The cycled nanocatalysts were found to exhibit a greater surface relaxation compared to noncycled catalysts. With 2-D lattice strain mapping, we show that the particle was about -3% strained with respect to pure Pt. While the observed enhancement in their activity is ascribed to such a strained lattice, our findings on the degradation kinetics establish that their extended catalytic durability is attributable to a sustained atomic order.

Date of Conference: 9-14 June 2013 Conventional 2D plasmonic structures, with surface coverage ~50%, provide field enhancement in the plane. The proposed 3D nanoplasmonic surfaces, with unity coverage, achieve 7.2-fold stronger out-of-plane enhancement compared to the 2D counterparts. © OSA 2013.

Conventional two-dimensional (2D) plasmonic arrays provide electric field intensity enhancement in the plane, typically with a surface coverage around 50% in the plan-view. Here, we show nanoplasmonic three-dimensional (3D) surfaces with 100% surface coverage enabling strong surface-normal field enhancement. Experimental measurements are found to agree well with the full electromagnetic solution. Along with the surface-normal localization when using the plasmonic 3D-surface, observed maximum field enhancement is 7.2-fold stronger in the 3D-surface than that of the 2D counterpart structure. 3D-plasmonic nonplanar surfaces provide the ability to generate volumetric field enhancement, possibly useful for enhanced plasmonic coupling and interactions. (C) 2013 Optical Society of America

Graphene is a perfect two-dimensional (2D) carbon sheet in honeycomb lattice with unique, multi-faceted properties. Very recently plasmons have been identified in graphene thus opening a new research field called “graphene plasmonics” which provides a suitable alternative to noble-metal plasmonics, since the associated surface plasmons (SPs) exhibit much larger light confinement abilities and relatively long propagation distances, with the advantage of being highly tunable via electrostatic gating. Moreover graphene can be efficiently integrated in photonic nanostructures in order to increase the optical absorption in the visible and infrared regions (graphene photonics). In this paper we will illustrate some applications of graphene plasmonics and graphene photonics, reported in literature, in different research fields and we will review our recent numerical and experimental results concerning the linear and nonlinear optical response of graphene plasmonic and photonic nanostructures emphasizing their interaction in terms of absorption and optical resonances.

We analyze the periodic contact between an elastic half-space and two types of rough substrates: (i) a perfect isotropically rough rigid substrate (2D isotropic roughness), and (ii) a perfect anisotropically rough rigid substrate, i.e. a substrate with roughness in only one direction (1D roughness). The analysis is carried out with the aid of proprietary codes, that we have developed (both in real and Fourier space) to deal with this type of contacts. Of course, 1D contacts differ from 2D isotropic contacts. However, our results and theoretical arguments suggest a possible criterion to make 2D contacts equivalent to 1D ones from the point of view of contact area and separation calculations. The rule consists in replacing the 2D power spectral density (PSD) of the isotropic surface into an equivalent 1D PSD. Interestingly the transformation rule does not depend on the statistical properties of the surface roughness, hence seems to have a universal character for isotropic surfaces.

The optical properties of a two-dimensional nanohole patterned aluminum thin film in hexagonal lattice are studied. The transmission dip can be moved out from the visible range by manipulating the lattice constant. The resulting nanopatterned thin film is demonstrated to exhibit a high transparency in a wide wavelength range. The origins of the transmission dip and the transmission drop are explained. For constant resistance, thicker films with a larger filling ratio lead to better transmittance in the visible range. Angular response of the nanopatterned metallic film is also analyzed, and transmittances using several other metals are compared. © 2012 American Institute of Physics.

A microfluidic system for rapid concentration, enumeration, and size based detection of microparticles is presented. The system includes a micro flow cytometer chip together with fluidics, optics and control on a single platform. The micro flow cytometer chip was designed, fabricated, and integrated with fluidics and optical fibers. The flow microchannel employs chevron structures at the top and bottom surfaces of the channel to achieve two-dimensional flow focusing. The system employs a cross-flow filter for sample concentration thus enabling enumeration and detection of microparticles even at low concentration levels (~1.1 � 104/ml). A flow stabilizer chip based on the concept of a fluid chamber with a flexible membrane as the top wall was used to reduce flow pulsations within the fluidic system thus improving measurement accuracy. The excitation optical fiber is connected to a laser source and the collection fibers are connected to photomultiplier tubes (PMTs) for signal manipulation and conversion. Labview was used for data acquisition through a PC interface. The ability of the system for enumeration and sizebased detection of microparticles was demonstrated using polystyrene microbeads suspended in PBS as the sample. Copyright � 2012 by ASME.

This article presents a study of large tape springs to be used as ribs of an ultra-thin shell space deployable reflector. The tape spring, both longitudinally and transversely curved, is made of carbon/epoxy composite and subject to two-dimensional or three-dimensional folds. The behaviour of tape springs with different dimensional parameters during folding is investigated by finite element analyses and an analytical approach. Peak moments, steady-state moments and strain levels are obtained for several parameters such as curvatures, length, thickness, subtended angle, etc. The analytical approach considers the bending strain energy during two-dimensional folding of the tape spring, and it does not capture the full behaviour due to the assumptions made for the simple solution. The results obtained by the two methods are compared where they are applicable and are in agreement for the tape springs subject to two-dimensional folds. Feasibility of the curved large tape springs as a rib-reinforcing element for the deployable reflector with 6 m diameter is investigated. A breadboard model of 90 cm diameter is manufactured and tested for packaging and deployment behaviour. © The Author(s) 2012 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Gas injection into a liquid cross flow from a nozzle causes bubble formations which have potential applications in industry such as chemical plants, waste water treatment and bio- and nuclear-reactors. The purpose of this study is to experimentally investigate the effects of nozzle shape and configuration with respect to the liquid cross-flow direction, on the bubbly flow characteristics such as bubble formation, detached bubble size and frequency at different gas and liquid flow rates. The experiments were conducted in a Plexiglas two-dimensional rig using a high speed camera. High speed imaging and an image processing algorithm were used to track each individual bubble and to quantify the bubble growth as well as the detachment frequency and the bubble velocity. Back light shadowgraphy which utilizes a low intensity diffuse light source to illuminate the background was used to image bubbles. Nozzles were mounted in the test section which was designed such that the flow in this section has a two-dimensional profile. The results showed that the bubble size increases with an increase in GLR (gas to liquid flow rates ratio). Furthermore, the bubble formations and detached bubble size were strongly influenced by the nozzle shape and configuration. Copyright © 2012 by ASME., ASME 2012 Fluids Engineering Division Summer Meeting, FEDSM 2012 Collocated with the ASME 2012 Heat Transfer Summer Conf. and the ASME 2012 10th International Conference on Nanochannels, Microchannels, and M, FEDSM 2012, 8 July 2012 through 12 July 2012, Rio Grande

A multiple scattering formulation of two-dimensional (2D) acoustic metamaterials is presented. This approach is comprehensive and can lead to frequency-dependent effective parameters (scalar bulk modulus and tensorial mass density), as it is possible to have not only positive or negative ellipsoidal refractive index, but also positive or negative hyperbolic refractive index. The correction due to multiple scattering interactions is included in the theory and it is demonstrated that its contribution is important only for lattices with high filling fractions. Since the surface fields on the scatterers are mainly responsible for the anomalous behavior of the resulting effective medium, complex scatterers can be used to engineer the frequency response. Anisotropic effects are also discussed within this formulation and some numerical examples are reported. A homogenization theory is also extended to electromagnetic wave propagation in 2D lattices of dielectric structures, where Mie resonances are found to be responsible for the metamaterial behavior. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft., This work was partially supported by the US Office of Naval Research under grant number N000140910554 and the Spanish Ministry of Science and Innovation under contract numbers TEC2010-19751 and CSD2008-66 (the CONSOLIDER program). Daniel Torrent also acknowledges support from the contract provided by the program 'Campus de Excelencia Internacional' 2010 UPV.

In this paper, we propose efficient and suitable effective surface models for steady laminar flows with heat transfer over rough surfaces. These models are developed in the frame of a domain decomposition method and consist in replacing the rough boundaries by effective smooth surfaces on which effective boundary conditions or wall laws are prescribed. The associated effective properties, namely the effective friction and heat transfer coefficients, are determined by the resolution of local closure problems over a representative pattern of the roughnesses. The impact of the flow parameters on these effective coefficients is analyzed, which allows to obtain useful estimates in some specific cases. Finally, two-dimensional numerical experiments are performed for a natural convection problem in a stamp shaped cavity to assess the validity of the proposed effective surface models. Throughout these tests, we also study numerically the impact of the position of the effective surface on momentum and heat transfers. © 2010 Elsevier Ltd. All rights reserved.

Ultralayered Co 3O 4 structures with high porosity have been synthesized by a facile homogeneous precipitation process under hydrothermal conditions. The superstructures consist of well-arranged micrometer length rectangular 2D flakes with high specific surface area, pore volume, and uniform pore size distribution. The electrochemical measurements demonstrate that charge storage occurs in ultralayered Co 3O 4 due to reversible redox reactions. The charge-discharge study shows that the material is capable of delivering very high specific capacitance of 548 F g -1 at a current density of 8 A g -1 and retains 66% of capacitance at 32 A g -1. The charge-discharge stability measurements show excellent specific capacitance retention capability, ca. 98.5% after 2000 continuous charge-discharge cycles at high current density of 16 A g -1. The exceptional cyclic, structural, and electrochemical stability at higher current rate with ?100% Coulombic efficiency, and very low ESR value from impedance measurements promise good utility value of ultralayered Co 3O 4 material in fabricating a wide range of high-performance electrochemical supercapacitors. � 2011 American Chemical Society.

Inverse Heat Transfer Problems (IHTP) are characterized by estimation of unknown quantities by utilizing any given information of the system. In this study, the inverse problem of estimation of heat generation in multiple two dimensional protruding heat sources on a vertical plate, a geometry frequently encountered in the cooling of electronic equipment, is carried out from the information available on the temperature distribution on the substrate on which these sources are mounted. A non-iterative method is applied utilizing Artificial Neural Networks (ANN) and covariance analysis to estimate the heat generation in the protruding heat sources on a vertical plate. The forward model involving laminar, two dimensional, steady, incompressible fluid flow and mixed convection heat transfer is numerically solved with FLUENT 6.3 for known values of heat generation in the protruding sources and the temperature distribution thus obtained on the PCB substrate is utilized to train the ANN for the inverse model. Parametric studies are conducted on the forward model to investigate the effect of Richardson number, Reynolds number, the chip and substrate conductivities on the heat dissipation to the fluid flowing over the heat sources. The trained networks are finally used to estimate the heat generation from the sources for a given temperature distribution on the substrate wall generated, for known values of the heat generation rates, which serve as the "measured" temperature distribution. Use is made of covariance analysis in order to identify the important temperature locations sufficient to carry out the inverse analysis. Finally, a systematic investigation on the effect of noise in the temperature "measurements" on the estimates also has been carried out. � 2010 Elsevier Masson SAS. All rights reserved.

We present a high performance surface plasmon resonance (SPR) sensor based on two dimensional (2D) ultra-thin (40 nm) gold nanoslit arrays. These structures were designed to exhibit narrow linewidth (FWHM) and high transmission SPR under non-polarized illumination. In addition, we show the influence of the geometrical design on the performance of these 2D slit arrays. The measured sensitivity (Sλ) of 2D slit arrays with a grating period of 620 nm is 600 nm/RIU, while the FWHM is as small as 22 nm. The obtained figure of merit (Sλ/FWHM) of 27/RIU is one of the highest reported values for such structures. Furthermore, we experimentally prove that 2D nanoslit arrays show narrower FWHM and higher transmission than 1D slit arrays under non-polarized illumination. The high figure of merit and polarization independence makes the 2D slit arrays especially suitable for further SPR sensor miniaturization through integration with a VCSEL or white light source, while keeping a high sensitivity. © 2011 IEEE.

This paper presents research on the development of a simulation method for the study of the mechanisms of intergranular crack nucleation and propagation in polycrystal metals on the mesoscale. Microstructural geometry models were built randomly using Voronoi techniques. Based on these grain structure geometry models, two-dimensional grain structure finite element models were created using a Patran Command Language (PCL) program. Techniques for the implementation of the cohesive elements between grain boundaries were developed in PCL for the generation of two-dimensional cohesive models. Simulations on intergranular crack nucleation and evolution along grain boundaries using two-dimensional finite element cohesive models were carried out on the mesoscale level. Several aspects that affect the crack nucleation and propagation were studied, which included random grain geometries, grain boundary misorientations, grain boundary peak strength, grain boundary fracture energy, grain properties, and grain plasticity. The simulations demonstrated that the cohesive model is a useful and efficient modeling tool for the study of the intergranular crack nucleation and evolution on the mesoscale level. The simulation results showed that the factors studied have large impacts on intergranular crack nucleation and evolution based on the current model capabilities and conditions. © 2011 WIT Press., 15th International Conference on Computational Methods and Experimental Measurements, CMEM 2011, 31 May 2011 through 2 June 2011, New Forest

Temperature dependent lasing was demonstrated in a dye-doped two-dimensional hexagonal photonic crystal made of holographic polymer-dispersed liquid crystals (LCs) along ΓM direction in TE polarization. A redshift in lasing peaks was observed as the temperature increased from 25 to 45 °C. The downward movement of photonic band of TE polarization, majorly caused by the decrease in the anisotropy of LC droplets with the increase in temperature, is responsible for the redshift in lasing peaks. © 2010 American Institute of Physics.

WOS: 000280000400052 We carried out the temperature (22-350 K) and magnetic field (0.05 and 1.4 T) dependent Hall mobility and carrier density measurements on Al(0.22)Ga(0.78)N/GaN heterostructures with AlN interlayer grown by metal-organic chemical-vapor deposition. Hall data is analyzed with a simple parallel conduction extraction method and temperature dependent mobility and carrier densities of the bulk and two-dimensional (2D) electrons are extracted successfully. The results for the bulk carriers are discussed using a theoretical model that includes the most important scattering mechanisms that contribute to the mobility. In order to investigate the mobility of two-dimensional electron gas, we used a theoretical model that takes into account the polar optical phonon scattering, acoustic phonon scattering, background impurity scattering, and interface roughness scattering in 2D. In these calculations, the values are used for the deformation potential and ionized impurity density values were obtained from the bulk scattering analysis. Therefore, the number of fitting parameters was reduced from four to two. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3456008] State Planning Organization of TurkeyTurkiye Cumhuriyeti Kalkinma Bakanligi [2001K120590]; European UnionEuropean Union (EU); TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [106E198, 107A004, 107A012]; Turkish Academy of SciencesTurkish Academy of Sciences This work is supported by the State Planning Organization of Turkey under Grant No. 2001K120590, by the European Union under the projects EU-PHOME and EU-ECONAM, and TUBITAK under the Project Nos. 106E198, 107A004, and 107A012. One of the authors (Ekmel Ozbay) acknowledges partial support from the Turkish Academy of Sciences.

The adsorption of anthracene (C14H10), at the mercury electrode/ethylene glycol (EG) solution interface, is characterized by a low and almost constant capacity (about 8 μF cm−2) region (capacitive “pit” or “plateau”) in capacity vs. potential curves, upon selection of suitable values of temperature, bulk concentration and applied potential values. This result is rationalized assuming the occurrence of a 2D phase transition between two distinct adsorbed phases: (i) a “disordered” phase, characterized by a flat “parallel” disposition of the aromatic moiety on the electrode surface (ii) an “ordered” phase, characterized by a “perpendicular” disposition of the aromatic moiety on the electrode surface. The experimental evidence is rationalized by considering the chemical potential as an explicit function of the “electric field/adsorbed molecule” interaction. Such a modelistic approach enables the determination of the relevant standard entropy variation.

A simplified heat and fluid flow model has been used to solve the Gas Tungsten Arc (GTA) linear welding problem for austenitic stainless steel. In this study, an equivalent 2-D (two-dimensional) transient heat and fluid flow model has been used to study the effect of controlled boundary conditions with free bottom surface and with bottom insulation. The governing equations have been solved by a finite volume method. The peak temperature, maximum velocity in the weld pool, weld bead width and depth get reduced when the bottom surface of the stainless steel plate is insulated. Copyright � 2010 Inderscience Enterprises Ltd.

A numerical study of laminar, boundary layer type diffusion flames established over a liquid fuel pool, under the influence of forced air flow parallel to the pool surface, has been carried out. Burning of a confined methanol pool at atmospheric pressure and under normal gravity conditions is investigated. A numerical model, which solves transient, two-dimensional, mass, momentum, species and energy conservation equations, has been employed to predict the flame characteristics. The gas-phase alone is solved in a decoupled manner using appropriate interface boundary conditions, without considering the effects of liquid-phase transport on the combustion process. A single-step global reaction for methanol-air oxidation, considering carbon-dioxide dissociation, is employed to model the chemical kinetics. An optically thin radiation model has also been incorporated to account for thermal radiation losses by absorbing species in a non-luminous flame. At the outset, the model is validated against the experimental results available in literature. Thereafter, it has been used to investigate the influence of free stream air velocity on fuel mass burning rate, flame stand-off distance, temperature and flow fields. The study brings out the variation in the structure of confined laminar boundary layer type diffusion flames over methanol pool for several air velocities under normal gravity environment. � 2010 Elsevier Ltd.

Composites fabricated by VARTM technology with the use of single-ply non-crimp 3D orthogonal woven preforms 3WEAVE (R) find fast growing research interest and industrial applications. It is now well understood and appreciated that this type of advanced composites provides efficient delamination suppression, enhanced damage tolerance, and superior impact, ballistic and blast performance characteristics over 2D fabric laminates. At the same time, this type of composites, having practically straight in-plane fibers, show significantly better in-plane stiffness and strength properties than respective properties of a "conventional" type 3D interlock weave composites. One primarily important question, which has not been addressed yet, is how the in-plane elastic and strength characteristics of this type of composites compare with respective in-plane properties of "equivalent" laminates made of 2D woven fabrics. This 2-part paper presents a comprehensive experimental study of the comparison of in-plane tensile properties of two single-ply non-crimp 3D orthogonal weave E-glass fiber composites on one side and a laminate reinforced with four plies of plain weave E-glass fabric on the other. Results obtained from mechanical testing are supplemented by acoustic emission data providing damage initiation thresholds, progressive cracks observation, full-field surface strain mapping and cracks observation on micrographs. The obtained results demonstrate that the studied 3D non-crimp orthogonal woven composites have considerably higher in-plane ultimate failure stresses and strains, as well as damage initiation strain thresholds than their 2D woven laminated composite counterpart. Part I presents the description of materials used, experimental techniques applied, principal results and their mutual comparisons for the three tested composites. Part 2 describes in detail the experimentally observed effects and trends with the main focus on the progressive damage: detailed results of AE registration, full-field strain measurements and progressive damage observations, highlighting peculiarities of local damage patterns and explaining the succession of local damage events, which leads to the differences in strength values between 2D and 3D composites. East-European PhD grant of K.U. Leuven Research Council (D.S. Ivanov) Department MTM

A thin liquid layer of a non-Newtonian film falling down an inclined plane that is subjected to nonuniform heating has been considered. The temperature of the inclined plane is assumed to be linearly distributed and the case when the temperature gradient is positive or negative is investigated. The film flow is influenced by gravity, mean surface tension, and thermocapillary forces acting along the free surface. The coupling of thermocapillary instability and surface-wave instabilities is studied for two-dimensional disturbances. A nonlinear evolution equation is derived by applying the long-wave theory, and the equation governs the evolution of a power-law film flowing down a nonuniformly heated inclined plane. The linear stability analysis shows that the film flow system is stable when the plate temperature decreases in the downstream direction while it is less stable for increasing temperature along the plate. Weakly nonlinear stability analysis using the method of multiple scales has been investigated and this leads to a secular equation of the Ginzburg-Landau type. The analysis shows that both supercritical stability and subcritical instability are possible for the film flow system. The results indicate the existence of finite-amplitude waves, and the threshold amplitude and nonlinear speed of these waves are influenced by thermocapillarity. The nonlinear evolution equation for the film thickness is solved numerically in a periodic domain in the supercritical stable region, and the results show that the shape of the wave is influenced by the choice of wave number, non-Newtonian rheology, and nonuniform heating. Copyright � 2009 by ASME.

A two-dimensional (2D) mathematical model in cylindrical coordinates has been formulated and used to predict the progress of conversion in a cylindrical wood particle undergoing pyrolysis in a fluidized bed. The transient model takes into account the heat consumed and shrinkage during drying and pyrolysis reactions in addition to anisotropy and changing thermal properties during the conversion. Predicted centre temperature has been compared with measurements found in the literature for validating the model. Calculations have been carried out for a 10 mm long and 10 mm diameter wooden cylinder in a bed of sand at 1107 K and fluidized by nitrogen. Developing profiles of temperature, solid-phase density, moisture content and degree of conversion at various stages have been presented. It is found that the conversion progresses faster and the gradients are steeper across the grains than along them. A comparison with a 1D model shows that thermal wave propagation predicted by the 2D model is faster than that of 1D. � 2008 Elsevier B.V. All rights reserved.

Tülek, Remziye (Balikesir Author), The transport properties of high mobility AlGaN/AlN/GaN and high sheet electron density AlInN/AlN/GaN two-dimensional electron gas (2DEG) heterostructures were studied. The samples were grown by metal-organic chemical vapor deposition on c-plane sapphire substrates. The room temperature electron mobility was measured as 1700 cm(2)/V s along with 8.44 X 10(12) cm(-2) electron density, which resulted in a two-dimensional sheet resistance of 435 Omega/square for the Al0.2Ga0.8N/AlN/GaN heterostructure. The sample designed with an Al0.88In0.12N barrier exhibited very high sheet electron density of 4.23 X 10(13) cm(-2) with a corresponding electron mobility of 812 cm(2)/V s at room temperature. A record two-dimensional sheet resistance of 182 Omega/square was obtained in the respective sample. In order to understand the observed transport properties, various scattering mechanisms such as acoustic and optical phonons, interface roughness, and alloy disordering were included in the theoretical model that was applied to the temperature dependent mobility data. It was found that the interface roughness scattering in turn reduces the room temperature mobility of the Al0.88In0.12N/AlN/GaN heterostructure. The observed high 2DEG density was attributed to the larger polarization fields that exist in the sample with an Al0.88In0.12N barrier layer. From these analyses, it can be argued that the AlInN/AlN/GaN high electron mobility transistors (HEMTs), after further optimization of the growth and design parameters, could show better transistor performance compared to AlGaN/AlN/GaN based HEMTs. c 2009 American Institute of Physics. [DOI: 10.1063/1.2996281], Turkiye Cumhuriyeti Kalkinma Bakanligi 2001K120590 Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) 104E090 105E066 105A005 106E198 106A017 Turkish Academy of Sciences

Further diversification of Hall sensor technology requires development of materials with high electron mobility and an ultrathin conducting layer very close to the material's surface. Here, we describe the magnetoresistive properties of micro-Hall devices fabricated using InAlSb/InAsSb/InAlSb heterostructures where electrical conduction was confined to a 30 nm-InAsSb two-dimensional electron gas layer. The 300 K electron mobility and sheet carrier concentration were 36 500 cm2 V-1 s-1 and 2.5× 1011 cm-2, respectively. The maximum current-related sensitivity was 2 750 V A-1 T-1, which was about an order of magnitude greater than AlGaAs/InGaAs pseudomorphic heterostructures devices. Photolithography was used to fabricate 1 μm×1 μm Hall probes, which were installed into a scanning Hall probe microscope and used to image the surface of a hard disk. © 2009 American Institute of Physics.

A reactive flow, the gelation of sodium acrylate (SA), was carried out in a cuboidal cavity with the top surface undergoing sinusoidal periodic motion. The instantaneous two-dimensional planar velocity fields during gelation were obtained using particle image velocimetry. The experiments were carried out with different plate velocities and different amounts of accelerator (TEMED). The temporal and spatial variations of the velocity components were analyzed. The magnitude of the velocity components was found to decrease with the progress of reaction due to gel formation. The role of mixing on the reaction is understood from the amount of gel formed at different plate velocities. Gel formation patterns are explained in terms of the mixing characteristics of the periodic flow. The periodic variation of point velocities showed the presence of higher harmonics in the flow. � 2008 The American Physical Society.

We develop a generalized plane strain (GPS) finite element formulation to predict the critical buckling voltage and temperature of a piezo composite beam in more generality than the cases characterized by plane strain and plane stress assumptions. This generalized plane strain formulation represents the two-dimensional finite element model as closely as possible to the three-dimensional finite element model. It is similar to the plane strain formulation that reduces a three-dimensional stress-strain relation to a two-dimensional one, but in contrast with most GPS formulations in the literature, it does not include out of plane degrees of freedom. In our formulation the reduced two-dimensional stress-strain relation incorporates the effect of allowed/applied strain"0 in the dimension not included in the two-dimensional model. Further, since the goal is to deal with thermal and electrical buckling analysis, an initial strain vector is incorporated in the formulation. A finite element solver based on an eight-node quadrilateral element was developed under the new formulation, and its results show good agreement with those reported by Varelis and Saravanos (2004) and those obtained with ANSYS. The critical electrical and thermal buckling loads for examples other than those characterized by plane stress and plane strain were analyzed, and it was found that they are significantly influenced by , the parameter controlling the out-of-plane strains. Finite element analysis of smart structures has attracted much attention in recent years due to its wide range of applications. A significant amount of research has gone into the analysis of piezo composite structures. A number of finite element (FE) models have been proposed for the analysis of smart structures; and a detailed survey is given in [Benjeddou 2000]. One of the main problems addressed is the buckling analysis of smart structures. Three-dimensional beam models can be simulated using two-dimensional in-plane elements by considering only the longitudinal cross-section of the three-dimensional beam model. The boundary conditions and the loading conditions can be simulated more accurately in this two-dimensional model than in the one-dimensional beam element model. Still, the two-dimensional analysis of the beam is based on either the plane stress or plane strain assumption, and cases outside these assumptions cannot be handled by two-dimensional in-plane elements. The generalized plane strain formulation can be used to model cases other than plane stress and plane strain at the cost of additional degrees of freedom. The generalized plane strain formulation has been discussed extensively in the literature and has been used for several applications. Most composite problems are generalized plane strain in nature, and they

A finite-element deterministic two-dimensional thermal elasto-plastic contact model is presented in this article, which facilitates the investigation of the influence of steady-state frictional heating on contacting asperities and subsurface stress fields. This model takes into account the asperity distortion caused by the temperature variation in a tribological process, microplastic flow of surface asperities, and coupled thermo-elasto-plastic behaviour of the material, with and without considering the strain-hardening property of the material. The model is verified through the contact analysis of a rigid, isothermal cylinder with a thermally conductive, elasto-plastic plane. The maximum contact pressures increase with frictional heating. Furthermore, thermal effects on the contact pressure, real area of the contact, and average gap of a real rough surface with different frictional heat inputs under thermal elasto-plastic contact conditions are numerically investigated. It indicates that neglecting thermal effect overestimates the real area of the contact and underestimates the average gap between the contacting surfaces.

The numerical study of combined laminar natural convection and surface radiation heat transfer in a modified cavity receiver of solar parabolic dish collector is presented in this paper. A two-dimensional simulation model for combined natural convection and surface radiation is developed. The influence of operating temperature, emissivity of the surface, orientation and the geometry on the total heat loss from the receiver is investigated. The convective heat loss from the modified receiver is significantly influenced by the inclination of the receiver whereas the radiation heat loss is considerably affected by surface properties of the receiver. The Nusselt number correlations are proposed separately for both natural convection and surface radiation based on large set of numerical data for a given range of parameters of practical interest. It is observed that the convection and radiation heat losses are found respectively 52% and 71.34% of the total heat loss at 0� inclination and 40.72% and 59.28% at 90� inclination for the modified cavity receiver with an area ratio of 8 and 400 �C. The convection and radiation numerical procedure is validated with other models. The results obtained from the present numerical procedure are in reasonable agreement with other well-known open cavity models. � 2007 Elsevier Masson SAS. All rights reserved.

A heat and fluid flow model has been developed to solve the gas tungsten arc (GTA) linear welding problem for austenitic stainless steel. The moving heat source problem associated with the electrode traverse has been simplified into an equivalent two-dimensional (2-D) transient problem. The torch residence time has been calculated from the arc diameter and torch speed. The mathematical formulation considers buoyancy, electromagnetic induction, and surface tension forces. The governing equations have been solved by the finite volume method. The temperature and velocity fields have been determined. The theoretical predictions for weld bead geometry are in good agreement with experimental measurements. � 2008 The Minerals, Metals & Materials Society and ASM International.

This paper reports the results of a numerical investigation of transient turbulent natural convection heat transfer from a volumetric energy generating source placed inside a cylindrical enclosure filled with low Prandtl number fluid (liquid sodium, Pr = 0.005). Two-dimensional conservation equations of mass, momentum and energy, coupled with the Boussinesq approximation, are solved using a finite volume based discretisation method employing the SIMPLE algorithm for the pressure velocity coupling. Turbulence is modeled using the k-? model with physical boundary conditions. The study presents the transient features of confined turbulent natural convection, due to time varying generation of heat in the volumetric source. The intensity of heat source exponentially decays with time and the source is placed over circular plates with a central opening. Results obtained from the numerical model compare favorably with those reported in the literature for steady state natural convection. Numerical simulations are carried out to display the sequential evolution of flow and thermal fields and the maximum temperature reached in the source. The advantages of distributing the heat source on multi trays have been quantified. � 2008 Elsevier Ltd. All rights reserved.

The time-dependent, compressible extrusion of a Carreau fluid is solved over the reservoir-die-extrudate region using finite elements in space and a fully implicit scheme in time. A nonmonotonic slip law based on experimental data on polyethylene melts is assumed to hold along the die wall and the velocity at the entrance of the reservoir is taken to be fixed and uniform. As in the case of the extrudate-swell flow, the combination of compressibility and nonlinear slip leads to self-sustained oscillations of the pressure drop and of the mass flow rate in the unstable regime. The effects of the reservoir volume, the imposed flow rate, and the capillary length on the amplitude and the frequency of the pressure and free surface oscillations are studied and comparisons are made with experimental observations. © 2006 Elsevier B.V. All rights reserved. 146 1-3 30 44 Cited By :16

We report the theoretical work on the photonic band gap structures suitable for microwave frequency region formed by magnetic materials (? = 9.87 and ? = 2.17) using plane wave expansion method. The structures under analysis are two-dimensional square and triangular lattices. The calculated band gap between 10 and 20 GHz region is anlaysed for the effect due to lattice spacing and the property of the material. The results are also compared with that of pure dielectric case. Obtained results indicate that both impedance and effective refractive index are responsible for the gap width and mid-gap frequency. � 2006 Elsevier B.V. All rights reserved.