• Steel and Composite Structures
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• v.25 no.3
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• pp.361-374
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• 2017

In this study, the influences of triaxial magnetic field on the wave propagation behavior of anisotropic nanoplates are studied. In order to include small scale effects, nonlocal strain gradient theory has been implemented. To study the nanoplate as a continuum model, the three-dimensional elasticity theory is adopted in Cartesian coordinate. In our study, all the elastic constants are considered and assumed to be the functions of (x, y, z), so all kind of anisotropic structures such as hexagonal and trigonal materials can be modeled, too. Moreover, all types of functionally graded structures can be investigated. eigenvalue method is employed and analytical solutions for the wave propagation are obtained. To justify our methodology, our results for the wave propagation of isotropic nanoplates are compared with the results available in the literature and great agreement is achieved. Five different types of anisotropic structures are investigated in present paper and then the influences of wave number, material properties, nonlocal and gradient parameter and uniaxial, biaxial and triaxial magnetic field on the wave propagation analysis of anisotropic nanoplates are presented. From the best knowledge of authors, it is the first time that three-dimensional elasticity theory and nonlocal strain gradient theory are used together with no approximation to derive the governing equations. Moreover, up to now, the effects of triaxial magnetic field have not been studied with considering size effects in nanoplates. According to the lack of any common approximations in the displacement field or in elastic constant, present theory has the potential to be used as a bench mark for future works.

• Structural Engineering and Mechanics
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• v.76 no.3
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• pp.293-310
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• 2020

This study derives the differential equations of free vertical bending and torsional vibrations for two- and three-pylon suspension bridges using d'Alembert's principle. The respective algorithms for natural vibration frequency and vibration mode are established through the separation of variables. In the case of the three-pylon suspension bridge, the effect of the along-bridge bending vibration of the middle pylon on the vertical bending vibration of the entire bridge is considered. The impact of torsional vibration of the middle pylon about the vertical axis on the torsional vibration of the entire bridge is also analyzed in detail. The feasibility of the proposed method is verified by two engineering examples. A comparative analysis of the results obtained via the proposed and more intricate finite element methods confirmed the former feasibility. Finally, the middle pylon stiffness effect on the vibration frequency of the three-pylon suspension bridge is discussed. It is found that the vibration frequencies of the first- and third-order vertical bending and torsional modes both increase with the middle pylon stiffness. However, the increase amplitudes of third-order bending and torsional modes are relatively small with the middle pylon stiffness increase. Moreover, the second-order bending and torsional frequencies do not change with the middle pylon stiffness.

• Structural Engineering and Mechanics
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• v.90 no.4
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• pp.325-343
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• 2024

Triple-tower double-cable suspension bridges have increased confinement stiffness imposed by the main cable on the middle tower, which has bright application prospects. However, vertical bending and torsional vibrations of the double-cable and the girder are coupled in such bridges due to the hangers. In particular, the bending vibration of the towers in the longitudinal direction and torsional vibrations about the vertical axis influence the vertical bending and torsional vibrations of the stiffening girders, respectively. The conventional analytical algorithm for assessing the dynamic features of the suspension bridge is not directly applicable to this type of bridge. This study attempts to mitigate this problem by introducing an analytical algorithm for solving the triple-tower double-cable suspension bridge's natural frequencies and mode shapes. D'Alembert's principle is employed to construct the differential equations of the vertical bending and torsional vibrations of the stiffening girder continuum in each span. Vibrations of stiffening girders in each span are interrelated via the vibrations of the main cables and the bridge towers. On this basis, the natural frequencies and mode shapes are derived by separating variables. The proposed algorithm is then applied to an engineering example. The natural frequencies and mode shapes of vertical bending and torsional vibrations derived by the analytical algorithm agreed well with calculations via the finite element method. The fundamental frequency of vertical bending and first- and second-order torsion frequencies of double-cable suspension bridges are much higher than those of single-cable suspension bridges. The analytical algorithm has high computational efficiency and calculation accuracy, which can provide a reference for selecting appropriate structural parameters to meet the requirements of dynamics during the preliminary design.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.53.2-53.2
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• 2015

We present preliminary results from a series of observations toward G108.8-00.8, which is one of Planck Cold Clumps and a promising candidate of massive prestellar cores. In the integrated intensity map of SCUBA 850 micron dust continuum emission, highly fragmented structures appear. These are distributed along one long filamentary structure seen in the CO 1-0 and 13CO 1-0 integrated intensity maps obtained with the PMO 13.7 m telescope. The northern part of the filament is divided into two parts, as seen in the CO 2-1, 13CO 2-1, and C18O 2-1 integrated intensity maps obtained with the CSO 10 m telescope. The observations of HCO+ 1-0, N2H+ 1-0, and HCN 1-0 with the IRAM 30 m telescope focus on the northern part of the CSO maps, which show a head-tail structure. NH3 (1,1) also shows similar distribution with IRAM maps. The depletion factors, derived by the comparison between the dust continuum and C18O 2-1 emission, varies from 1.5 to 6 over the region, suggesting different evolutionary status of each component. To study the chemical and physical environments of G108.8-00.8, more detailed analysis is in progress.

• Annals of Clinical Neurophysiology
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• v.19 no.2
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• pp.101-112
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• 2017

Detection of underling proteinopathies is becoming increasingly important across neurodegenerative conditions due to upcoming disease intervention trials. In this review, we explored how temporal lobe changes in amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) can potentially predict underlying TDP-43 pathology subtypes in FTD. To date, emphasis has been given to frontal lobe changes in the study of the cognitive and behavioural impairments in both syndromes but an increasing number of pathological, imaging and neuropsychological studies suggest how temporal lobe changes could critically affect the cognition and behaviour of these conditions. In this current article, we reviewed pathological, imaging as well as clinical/neuropsychological findings of temporal involvement in the ALS-FTD continuum, how they relate to temporal lobe changes and the underlying TDP-43 pathology in FTD. Findings across studies show that TDP-43 pathology occurs and coincides in many structures in ALS and FTD, but especially in the temporal lobes. In particular, anterior and medial temporal lobes atrophy is consistently found in ALS and FTD. In addition, memory and language impairment as well as emotional and Theory of Mind processing deficits that are characteristics of the two diseases are highly correlated to temporal lobe dysfunction. We conclude by showing that temporal lobe changes due to TDP-43 type B might be particular predictive of TDP-43 type B pathology in behavioural variant FTD, which clearly needs to be investigated further in the future.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.73.2-73.2
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• 2012

The far ultraviolet (FUV) wavelength (900-1750A) range includes a wealth of important astrophysical information related to the cooling of hot gas, fluorescent emission from H2 molecules, and starlight scattered off dust particles. Among these, we would like to focus on the scattered emission of the central star by dust with the example of the FUV halo surrounding ${\alpha}$ Vir (Spica). While scattering properties of dust have been studied with the GALEX data, the improved dataset of STSAT-1 revealed many detailed structures of this interesting region. For example, the FUV continuum map obtained from the STSAT-1 observations shows enhanced emission in the southern part of the Spica halo region, where the dust level is also high. In fact, the FUV continuum intensity is seen to have a good correlation with the IRAS 100${\mu}m$ emission data. It is also seen that the scattered spectrum is softer than the original one emitted by the central star, which is attributed to the increase in the dust-scattering albedo with wavelength. We have developed a Monte Carlo code that simulates dust scattering of light including multiple encounters. The code is applied to the present Spica halo region to obtain the scattering properties such as the albedo and the phase function asymmetry factor.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.6
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• pp.914-921
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• 2010

When industrial structures are constructed on soft ground, ground subsidence is occurred by problems of bearing capacity. To protect ground subsidence have to improve soft ground, and have to predict settlement estimation for reasonable construction. Artificial Neural Networks(ANN) is adopted for prediction of settlement of construction during the initial design. In the study, Artificial Neural Networks are applied to predict the settlement estimation of initial condition ground and ground improved by D.C.M method. Also, this study compares results of Artificial Neural Networks and results of continuum analysis using Mohr-Coulomb models. In result, settlements of initial condition ground decreased over 0.7 times. Also, by comparing ANN and continuum analysis, coefficient of determination was comparatively high value 0.79. Thought this study, it was confirmed that settlements of improvement ground is predicted using laboratory experiment data.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.115.2-115.2
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• 2011

UWISH2 (UKIRT Widefield Infrared Survey for $H_2$) is an unbiased, narrow-band imaging survey of the Galactic plane in the $H_2$ 1-0 S(1) emission line at $2.122{\mu}m$ using the Wide-Field Camera (WFCAM) at the United Kingdom Infrared Telescope (UKIRT). The survey covers about 150 square degrees of the first Galactic quadrant ($10^{\circ}$ < l < $65^{\circ}$; $-1.3^{\circ}$ < b < $+1.3^{\circ}$). The images have a $5{\sigma}$ detection limit of point sources of K~18 mag and the surface brightness limit is $10^{-19}\;W\;m^{-2}$ $arcsec^{-2}$. The survey operation began on 28 July 2009 and has completed on 17 August 2011. We have been studying the supernova remnants (SNRs) in the UWISH2 survey area. Among the known 274 Galactic SNRs, the survey area includes 65 SNRs or 24 percent of the known SNRs. The wide-field and high-quality UWISH2 images allow us to identify both the diffuse extended and compact $H_2$ emission associated with SNRs, which is useful for understanding their physical environment and evolution. The continuum is subtracted from the narrow-band $H_2$ images using the K-band continuum images obtained as part of the UKIDSS GPS (UKIRT Infrared Deep Sky Survey of the Galactic Plane). So far, we have inspected 42 SNRs, and found distinct H2 emission in 14 SNRs. The detection rate is 33%. Some of the SNRs show bright, complex, and interesting structures that have never been reported in previous studies. In this report, we present our identification scheme and preliminary results.

• Computational Structural Engineering
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• v.10 no.4
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• pp.315-325
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• 1997

This paper describes the application of discretized continuum-type optimality criteria (DCOC) and the development of optimum design program for the multispan partially prestressed concrete beams. The cost of construction as objective function which includes the costs of concrete, prestressing steel, non-prestressing steel and formwork is minimized. The design constraints include limits on the maximum deflection, flexural and shear strengths, in addition to ductility requirements, and upper and lower bounds on design variables as stipulated by the design Code. Based on Kuhn-Tucker necessary conditions, the optimality criteria are explicitly derived in terms of the design variables-effective depth, eccentricity of prestressing steel and non-prestressing steel ratio. The prestressing profile is prescribed by parabolic functions. The self-weight of the structure is included in the equilibrium equation of the real system, as is the secondary effect resulting from the prestressing force. An iterative procedure and computer program for updating the design variables are developed. Two numerical examples of multispan PPC beams with rectangular cross-section are solved to show the applicability and efficiency of the DCOC-based technique.

• Steel and Composite Structures
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• v.20 no.3
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• pp.623-649
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• 2016

Most of the early studies on plates vibration are focused on two-dimensional theories, these theories reduce the dimensions of problems from three to two by introducing some assumptions in mathematical modeling leading to simpler expressions and derivation of solutions. However, these simplifications inherently bring errors and therefore may lead to unreliable results for relatively thick plates. The main objective of this research paper is to present 3-D elasticity solution for free vibration analysis of continuously graded carbon nanotube-reinforced (CGCNTR) rectangular plates resting on two-parameter elastic foundations. The volume fractions of oriented, straight single-walled carbon nanotubes (SWCNTs) are assumed to be graded in the thickness direction. In this study, an equivalent continuum model based on the Eshelby-Mori-Tanaka approach is employed to estimate the effective constitutive law of the elastic isotropic medium (matrix) with oriented, straight carbon nanotubes (CNTs). The proposed rectangular plates have two opposite edges simply supported, while all possible combinations of free, simply supported and clamped boundary conditions are applied to the other two edges. The formulations are based on the three-dimensional elasticity theory. A semi-analytical approach composed of differential quadrature method (DQM) and series solution is adopted to solve the equations of motion. The fast rate of convergence of the method is demonstrated and comparison studies are carried out to establish its very high accuracy and versatility. The 2-D differential quadrature method as an efficient and accurate numerical tool is used to discretize the governing equations and to implement the boundary conditions. The convergence of the method is demonstrated and to validate the results, comparisons are made between the present results and results reported by well-known references for special cases treated before, have confirmed accuracy and efficiency of the present approach. The novelty of the present work is to exploit Eshelby-Mori-Tanaka approach in order to reveal the impacts of the volume fractions of oriented CNTs, different CNTs distributions, various coefficients of foundation and different combinations of free, simply supported and clamped boundary conditions on the vibrational characteristics of CGCNTR rectangular plates. The new results can be used as benchmark solutions for future researches.