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This paper presents a method for improved analysis of objects with an axial symmetry using X-ray Computed Tomography (CT). Cylindrical coordinates about an axis fixed to the object form the most natural base to check certain characteristics of objects that contain such symmetry, as often occurs with industrial parts. The sampling grid corresponds with the object, allowing for down-sampling hence reducing the reconstruction time. This is necessary for in-line applications and fast quality inspection. With algebraic reconstruction it permits the use of a pre-computed initial volume perfectly suited to fit a series of scans where same-type objects can have different positions and orientations, as often encountered in an industrial setting. Weighted back-projection can also be included when some regions are more likely subject to change, to improve stability. Building on a Cartesian grid reconstruction code, the feasibility of reusing the existing ray-tracers is checked against other researches in the same field., 13 pages, 13 figures. submitted to Journal Of Nondestructive Evaluation (https://www.springer.com/journal/10921)

Near-field acoustical holography (NAH) is conventionally used to visualize sound fields in a three-dimensional space based on sound pressure measurements conducted on a surface close to a noise source. Traditional Fourier-based acoustical holography procedures require the use of a large microphone array setup to avoid spatial truncation effects: that means it is necessary that the array be large enough so that the sound pressure level measured at the edges of the array is significantly lower than that at the peak locations. To avoid the need to use large microphone arrays, a method referred to as statistically optimized near-field acoustical holography (SONAH), was proposed by Steiner and Hald, initially in planar coordinates. In that method, an extension of the measurement surface well beyond the actual source surface is not necessary since the projected sound field is calculated by using a transfer matrix defined in such a way such the propagating waves and evanescent waves are optimally represented. In the current work, the development of SONAH in cylindrical coordinates as formulated by Cho, Bolton, and Hald is first reviewed and is then applied to the observation of the sound field generated by a bladeless fan. It will be shown that the noise source locations can be clearly identified at significant frequencies by using this procedure, and that a knowledge of the source locations makes it possible to suggest effective noise control solutions targeted at specific frequencies.

There is a growing interest in using unmanned underwater vehicles to perform a large array of tasks that require operation near the surface, and the wave-induced loads experienced by these vessels play an important role in their design and operation. An analytic solution can predict first-order loads on a submerged body using potential flow theory. However, potential flow does not take into account viscous effects, which can also be significant in the hydrodynamic loads experienced. Experimental model tests were performed using a wave generation tow tank, where both potential and viscous effects were acting on a submerged body, at speed, near the surface. Two different geometries were tested to model these submerged bodies. One model was a cylindrical body with hemispheric endcaps. The second model was a cylindrical body with circular, flat-faced endcaps. Experiments on both models were performed to measure hydrodynamic loads for three different speeds over various wavelengths, at two model depths, and for one wave height. The measured loads were then compared and analyzed against the predicted loads from the analytic solution, and the significance of viscous loads was determined. http://archive.org/details/studyofwaveinduc1094562748 Lieutenant, United States Navy Approved for public release; distribution is unlimited.

Small-diameter vascular grafts fabricated from synthetic polymers have found limited applications so far in vascular surgeries, owing to their poor mechanical properties. In this study, cylindrical nanofibrous structures of highly oriented nanofibers made from polyacrylonitrile, poly (lactide-co-glycolide) (PLGA), polycaprolactone (PCL) and poly(vinyl acetate) (PVAc) were investigated. Cylindrical collectors with alternate conductive and non-conductive segments were used to obtain highly oriented nanofibrous structures at the same time with better mechanical properties. The surface morphology (orientation), mechanical properties and suture retention of the nanofibrous structures were characterized using SEM, mechanical tester and universal testing machine, respectively. The PLGA nanofibrous cylindrical structure exhibited excellent properties (tensile strength of 9.1 ± 0.6 MPa, suture retention strength of 27N and burst pressure of 350 ± 50 mmHg) when compared to other polymers. Moreover, the PLGA grafts showed good porosity and elongation values, that could be potentially used for vascular graft applications. The combination of PLGA nanofibers with extracellular vesicles (EVs) will be explored as a potential vascular graft in future.

Solar energy is used not only at low latitudes, where it is available at large amounts, but also at higher latitudes, where height of sun and irradiance are significantly lower. On the other hand, the length of day at higher latitudes is longer in summer than at low latitudes, and also the path of the sun is longer. The present research deals with seeking for new shapes of solar collectors capable of receiving more solar energy. For designing and evaluating new shapes of solar collectors, it is necessary to have new methods for simple calculations of energy received from the sun by surface of any shape and direction. Such a method is explained in the present paper. Based on calculations by the proposed method, a new form of solar collector – a cylindrical collector – has been worked out. This collector is intended for air heating, but main principles can also be used for water heating, and even for photovoltaics. A cylindrical collector receives more energy in the morning and evening than a flat one, but at midday power of both collectors is equal, if effective areas are equal. Daily energy sum of the cylindrical solar collector is 1.5 times greater than that of the flat one.

The intrinsic optical bistability of the nonlinear composite consisting of coated cylinders with nonlinear core and graded Drude shell is investigated with self-consistent mean-field approximation. We derive the nonlinear equation of near field for such graded composite in the quasistatic limit. We demonstrate that the bistability threshold and the bistable width are highly dependent on the core radius, the incident frequency, and the graded coefficient of the coated cylinder inclusion. It is found that the optical bistability appears only when the core radius and the incident frequency satisfy some specific conditions. Therefore, the optical bistability for nonlinear composite materials may be optimized by the suitable adjustment of the physical and geometrical parameters. Our results may be helpful for the design of the nonlinear device with appropriate bistability.

A method of solution to solve the compressible 3D Navier-Stokes Equations in cylindrical co-ordinates coupled to the continuity equation in cylindrical coordinates is presented in terms of an additive solution of the three principle directions in the radial, azimuthal and z directions of flow. A dimensionless parameter is introduced whereby in the large limit case a method of solution is sought for in the boundary layer of the tube. It is concluded that the total divergence of the flow can be expressed as the integral with respect to time of the line integral of the dot product of inertial and azimuthal velocity. The line integral is evaluated on a contour that is annular and traces the boundary layer as time increases in the flow. Finally it's explicit dependence on the gradient of a density function and Laplacian of pressure is shown with complete dependence on the vorticity and it's rate of change for a flow associated with the Navier Stokes equations.

Open channel flow is the natural phenomenon that research by hydraulic engineer. Roughness of thechannel is the drag factor of the flow and the value depend on the roughness caracteristics. Chezy coefficient is the coefficient of flow equation determining velocity at the channel. The value of the chezy coefficient is depend of flow caracteristics and roughness of the channel. Research target conducted to learn the value of the chezy coefficient and drag coefficient at the open channel flow with the cylindrical roughness and determine the parameter having an effect on and also relation usher the parameter. The result of cylindrical will be application to the flow with the resistance grow on mangrove. This research used 6 vertical bar model by 6 variation of density to 2 vertical bar diameter. Simulation model the vertical bar conducted by 4 variation of discharge the stream range from 0,00825 until 0,01374 m3/s and 5 variation of stream deepness by turning around back door ( tail gate). Scale model 1 : 10 used to support the measurement correctness beside consideration of equipments limitation. Research data analysis use the way of comparison between theoretical with the research to yield the relation of non dimensionaless. Result of this research indicate that ever greater of density, depth flow and diameter of cylindrical hence yielded chezy coefficient smaller that mean drag flow is greater. Chezy coefficient yielded range 3,82 – 10,579 m1/2/s with the density range 0,498 – 6,883 while drag coefficient value result of average 0,95. Average velocity for cylindrical roughness can be determine with the equation of Chezy

A new angles-only initial relative orbit determination (IROD) algorithm is derived using three line-of-sight observations. This algorithm accomplishes this by taking a Singular Value Decomposition of a 6x6 matrix to arrive at an approximate initial relative orbit determination solution. This involves the approximate solution of 6 polynomial equations in 6 unknowns. An iterative improvement algorithm is also derived that provides the exact solution, to numerical precision, of the 6 polynomial equations in 6 unknowns. The initial relative orbit algorithm is also expanded for more than three line-of-sight observations with an iterative improvement algorithm for more than three line-of-sight observations. The algorithm is tested for a range of relative motion cases in low earth orbit and geosynchronous orbit, with and without the inclusion of J2 perturbations and with camera measurement errors. The performance of the IROD algorithm is evaluated for these cases and show that the tool is most accurate at low inclinations and eccentricities. Results are also presented that show the importance of including J2 perturbations when modelling the relative orbital motion for accurate IROD estimates. This research was funded in part by the Air Force Research Lab, Albuquerque, NM.

Radially polarized piezoelectric fibers are now considered to be used in smart composites. The piezoelectric layers in these fibers are generally anisotropic in the transverse direction and therefore difficult to analyze when dynamic loads are involved. The present paper presents a theoretical study of the dynamic behavior of radially polarized cylindrical piezoelectric layers between isotropic elastic media. A new interphase model is developed to provide simple yet accurate evaluation of the dynamic response of such anisotropic elastic layers. Unlike the traditional interface-spring model, the current interphase model satisfies the equations of motion of the layers and can provide reliable prediction of the stress and displacement. A comparison between the developed model, the interface-spring model and the finite element analysis is conducted. The results clearly show the advantages of the current model over the traditional interface-spring model in simulating anisotropic layers. Numerical examples based on this interphase model for different interphase thicknesses, loading frequencies and material combinations are presented to evaluate the dynamic behavior of multilayered elastic media.

Static analysis of skew composite shells is presented by developing a C0 finite element (FE) model based on higher order shear deformation theory (HSDT). In this theory the transverse shear stresses are taken as zero at the shell top and bottom. A realistic parabolic variation of transverse shear strains through the shell thickness is assumed and the use of shear correction factor is avoided. Sander's approximations are considered to include the effect of three curvature terms in the strain components of composite shells. The C0 finite element formulation has been done quite efficiently to overcome the problem of C1 continuity associated with the HSDT. The isoparametric FE used in the present model consists of nine nodes with seven nodal unknowns per node. Since there is no result available in the literature on the problem of skew composite shell based on HSDT, present results are validated with few results available on composite plates/shells. Many new results are presented on the static response of laminated composite skew shells considering different geometry, boundary conditions, ply orientation, loadings and skew angles. Shell forms considered in this study include spherical, conical, cylindrical and hypar shells.

Chiral cylindrical molecular complexes of homo- and hetero-double-helices derived from helicene oligomers self-assemble in solution, providing functional heterogeneous liquid-solid materials. Gels and liotropic liquid crystals are formed by fibril self-assembly in solution; molecular monolayers and fibril films are formed by self-assembly on solid surfaces; gels containing gold nanoparticles emit light; silica nanoparticles aggregate and adsorb double-helices. Notable dynamics appears during self-assembly, including multistep self-assembly, solid surface catalyzed double-helix formation, sigmoidal and stairwise kinetics, molecular recognition of nanoparticles, discontinuous self-assembly, materials clocking, chiral symmetry breaking and homogeneous-heterogeneous transitions. These phenomena are derived from strong intercomplex interactions of chiral cylindrical molecular complexes.

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2011, Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2011, Bu çalışma silindirik bir kabuğun çeşitli fiziksel özelliklerde ve yükler altında nasıl davrandığını içermektedir. Bunun yanısıra kompozit ve aluminyum plakaların kıyaslaması yapılmıştır. Abaqus den elde edilen sonuçlarla deneysel sonuçlar karşılaştırılmıştır., This research will show us how the behaviour of sandwich structured composites having a cylindrical shape changes according to changing core thickness and fiber orientation under general vibration and impact loads. Moreover, comparison between composites and aluminum can be reached throughout this research. Abaqus and experimental results are compared., Yüksek Lisans, M.Sc.

Cylindrical Nearfield Acoustical Holography (NAH) based on a multi-scan, cross-spectral measurement was used to visualize the sound field of a ducted fan, and the ability of this procedure to quantify source modification effects is illustrated here.