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Sample records for 3d surface roughness

  1. Studies of the 3D surface roughness height

    SciTech Connect

    Avisane, Anita; Rudzitis, Janis; Kumermanis, Maris

    2013-12-16

    Nowadays nano-coatings occupy more and more significant place in technology. Innovative, functional coatings acquire new aspects from the point of view of modern technologies, considering the aggregate of physical properties that can be achieved manipulating in the production process with the properties of coatings’ surfaces on micro- and nano-level. Nano-coatings are applied on machine parts, friction surfaces, contacting parts, corrosion surfaces, transparent conducting films (TCF), etc. The equipment available at present for the production of transparent conducting oxide (TCO) coatings with highest quality is based on expensive indium tin oxide (ITO) material; therefore cheaper alternatives are being searched for. One such offered alternative is zink oxide (ZnO) nano-coatings. Evaluating the TCF physical and mechanical properties and in view of the new ISO standard (EN ISO 25178) on the introduction of surface texture (3D surface roughness) in the engineering calculations, it is necessary to examine the height of 3D surface roughness, which is one of the most significant roughness parameters. The given paper studies the average values of 3D surface roughness height and the most often applied distribution laws are as follows: the normal distribution and Rayleigh distribution. The 3D surface is simulated by a normal random field.

  2. Studies of the 3D surface roughness height

    NASA Astrophysics Data System (ADS)

    Avisane, Anita; Rudzitis, Janis; Kumermanis, Maris

    2013-12-01

    Nowadays nano-coatings occupy more and more significant place in technology. Innovative, functional coatings acquire new aspects from the point of view of modern technologies, considering the aggregate of physical properties that can be achieved manipulating in the production process with the properties of coatings' surfaces on micro- and nano-level. Nano-coatings are applied on machine parts, friction surfaces, contacting parts, corrosion surfaces, transparent conducting films (TCF), etc. The equipment available at present for the production of transparent conducting oxide (TCO) coatings with highest quality is based on expensive indium tin oxide (ITO) material; therefore cheaper alternatives are being searched for. One such offered alternative is zink oxide (ZnO) nano-coatings. Evaluating the TCF physical and mechanical properties and in view of the new ISO standard (EN ISO 25178) on the introduction of surface texture (3D surface roughness) in the engineering calculations, it is necessary to examine the height of 3D surface roughness, which is one of the most significant roughness parameters. The given paper studies the average values of 3D surface roughness height and the most often applied distribution laws are as follows: the normal distribution and Rayleigh distribution. The 3D surface is simulated by a normal random field.

  3. Investigation Into the Accuracy of 3D Surface Roughness Characteristics

    NASA Astrophysics Data System (ADS)

    Kumermanis, M.; Rudzitis, J.; Mozga, N.; Ancans, A.; Grislis, A.

    2014-04-01

    The existing standards for surface roughness cover only two dimensions, while in reality this is three-dimensional (3D). In particular, the 3D surface roughness parameters are important for solving the contact surface mechanics problems as related to the accuracy of 3D surface roughness characteristics. One of the most important factors for determination of 3D characteristics is the number of data points (NDP) on the x- and y-axes (i.e. in cut-off length). The NDP has a profound effect on the accuracy of measurement results, measuring time and volume of the output data (especially along the y-axis, where the NDP is identical to the number of parallel profiles). At a too small NDP the results will be incorrect and with too broad scatter, while a too large NDP - though not enlarging the range of basic information - considerably increases the measuring time. Therefore, the aim of the work was to find the optimal NDP for such surface processing methods as grinding, spark erosion and shot methods of surface treatment. Eksistējošie virsmas raupjuma standarti apskata virsmas raupjumu tikai divās dimensijās. Tomēr reālais virsmas raupjums pēc savas dabas ir trīsdimensiju (3D) objekts. Līdz ar to virsmas raupjums ir jāraksturo ar 3D parametriem. Un no šo parametru noteikšanas precizitātes ir atkarīgi tālākie virsmas aprēķini, piemēram, virsmu kontaktēšanās process. Viens no svarīgākajiem faktoriem, raksturojot virsmas raupjumu 3D, pielietojot kontakta tipa mēriekārtas, ir datu punktu skaits pa abām mērīšanas asīm x un y. Ar datu punktu skaitu mēs saprotam to skaitu mērīšanas bāzes garumā. Datu punktu skaits būtiski ietekmē sagaidāmo mērījumu rezultātu precizitāti, mērīšanai nepieciešamo laiku un izejas datu faila izmērus (sevišķi y-ass virzienā, kur katrs datu punkts ir paralēls profils). Datu punktu skaitam ir jābūt optimālam. Pārāk mazs punktu skaits noved pie neprecīziem rezultātiem un lielas to izkliedes, savuk

  4. 3D surface roughness measurement for scaliness scoring of psoriasis lesions.

    PubMed

    Ahmad Fadzil, M Hani; Prakasa, Esa; Asirvadam, Vijanth Sagayan; Nugroho, Hermawan; Affandi, Azura Mohd; Hussein, Suraiya Hani

    2013-11-01

    Psoriasis is an incurable skin disorder affecting 2-3% of the world population. The scaliness of psoriasis is a key assessment parameter of the Psoriasis Area and Severity Index (PASI). Dermatologists typically use visual and tactile senses in PASI scaliness assessment. However, the assessment can be subjective resulting in inter- and intra-rater variability in the scores. This paper proposes an assessment method that incorporates 3D surface roughness with standard clustering techniques to objectively determine the PASI scaliness score for psoriasis lesions. A surface roughness algorithm using structured light projection has been applied to 1999 3D psoriasis lesion surfaces. The algorithm has been validated with an accuracy of 94.12%. Clustering algorithms were used to classify the surface roughness measured using the proposed assessment method for PASI scaliness scoring. The reliability of the developed PASI scaliness algorithm was high with kappa coefficients>0.84 (almost perfect agreement). PMID:24054912

  5. Characterizing the influence of surface roughness and inclination on 3D vision sensor performance

    NASA Astrophysics Data System (ADS)

    Hodgson, John R.; Kinnell, Peter; Justham, Laura; Jackson, Michael R.

    2015-12-01

    This paper reports a methodology to evaluate the performance of 3D scanners, focusing on the influence of surface roughness and inclination on the number of acquired data points and measurement noise. Point clouds were captured of samples mounted on a robotic pan-tilt stage using an Ensenso active stereo 3D scanner. The samples have isotropic texture and range in surface roughness (Ra) from 0.09 to 0.46 μm. By extracting the point cloud quality indicators, point density and standard deviation, at a multitude of inclinations, maps of scanner performance are created. These maps highlight the performance envelopes of the sensor, the aim being to predict and compare scanner performance on real-world surfaces, rather than idealistic artifacts. The results highlight the need to characterize 3D vision sensors by their measurement limits as well as best-case performance, determined either by theoretical calculation or measurements in ideal circumstances.

  6. How to select the most relevant 3D roughness parameters of a surface.

    PubMed

    Deltombe, R; Kubiak, K J; Bigerelle, M

    2014-01-01

    In order to conduct a comprehensive roughness analysis, around sixty 3D roughness parameters are created to describe most of the surface morphology with regard to specific functions, properties or applications. In this paper, a multiscale surface topography decomposition method is proposed with application to stainless steel (AISI 304), which is processed by rolling at different fabrication stages and by electrical discharge tool machining. Fifty-six 3D-roughness parameters defined in ISO, EUR, and ASME standards are calculated for the measured surfaces. Then, expert software "MesRug" is employed to perform statistical analysis on acquired data in order to find the most relevant parameters characterizing the effect of both processes (rolling and machining), and to determine the most appropriate scale of analysis. For the rolling process: The parameter Vmc (the Core Material Volume--defined as volume of material comprising the texture between heights corresponding to the material ratio values of p = 10% and q = 80%) computed at the scale of 3 µm is the most relevant parameter to characterize the cold rolling process. For the EDM Process, the best roughness parameter is SPD that represents the number of peaks per unit area after segmentation of a surface into motifs computed at the scale of 8 µm. PMID:24038147

  7. Determination of 3D Surface Roughness Parameters by Cross-Section Method

    NASA Astrophysics Data System (ADS)

    Rudzitis, J.; Krizbergs, J.; Kumermanis, M.; Mozga, N.; Ancans, A.; Leitans, A.

    2014-04-01

    Currently, in the production engineering the surface roughness parameters are estimated in three dimensions, however, the equipment for these measurements is rather expensive and not always available. In many cases to buy such equipment is not economically justified. Therefore, the 3D surface roughness parameters are usually determined from the well-known 2D profile ones using the existing 2D equipment. This could be done best using the cross-section (or profile) method, especially in the case of nanoroughness estimation, with calculation of the mean values for the roughness height, spacing, and shape. This method - though mainly meant for irregular rough surfaces - can also be used for other types of rough surfaces. Particular emphasis is here given to the correlation between the surface cross-section (profile) parameters and 3D parameters as well as to the choice of the number of cross-cuttings and their orientation on the surface. Mūsdienu ražošanā ir nepieciešams novērtēt virsmas raupjuma parametrus trijās dimensijās, tomēr, aprīkojums šādu mērījumu veikšanai ir ļoti dārgs un ne vienmēr pieejams. Tādēļ bieži rodas nepieciešamība noteikt 3D virsmas raupjuma parametrus pēc labi zināmajiem profila (2D) parametriem, izmantojot eksistējošo 2D mērīšanas aprīkojumu. Labākais risinājums šai problēmai ir izmantot 3D raupjuma parametru noteikšanai šķēlumu jeb profilu metodi. Metode uzrāda labus rezultātus arī novērtējot nanoraupjumu. Iespējams aprēķināt sekojošu virsmas raupjuma mikrotopogrāfisko parametru vidējās vērtības: raupjuma augstumu; soļu parametrus un formu. Metode ir paredzēta izmantošanai virsmām ar neregulāru raksturu, bet var tikt pielāgota arī citu tipu virsmām.

  8. 3D parameter to quantify the anisotropy measurement of periodic structures on rough surfaces.

    PubMed

    Guillemot, G; Bigerelle, M; Khawaja, Z

    2014-01-01

    In this paper, a new 3D roughness parameter, Sreg, is proposed to quantify the regularity of a surface, independent of the amplitude and the scanning length units of the surface. The efficiency of this parameter is tested on noisy periodical surfaces with degrees of anisotropy. This parameter lies between zero (perfect noise) and 100% (a perfect periodic surface). This parameter enables the identification of the anisotropy directions of regularity for a given surface. For a periodical surface, the greater the noise, the lower the anisotropy. A direction function is proposed to analyse the direction of regularity of a rough surface, which then permits characterization of the directional regularity of the topography. The regularity parameter can be used for several purposes: to identify the direction of periodical structures formed by laser-pulsed radiations on the surface of solid workpieces; to examine the reproducibility of surface machining methods such as finishing process; and to identify the surface regularity produced by abrasive machining, such as precision surface grain, abrasive slotting, and lapping. PMID:23824916

  9. 3D surface roughness recreation and data processing of granitic rocks and claystones, potential host rocks for radioactive waste disposal

    NASA Astrophysics Data System (ADS)

    Buocz, Ildikó; Török, Ákos; Rozgonyi-Boissinot, Nikoletta

    2015-04-01

    The determination and modelling of the stability of rock slopes, tunnels, or underground spaces, i.e. radioactive waste disposal facilities, is an important task in engineering. The appropriate estimation of the mechanical parameters for a realistic description of the behaviour of rocks results in higher safety and more economic design. The failure of stability is primarily due to the shear failure of the rock masses along fractures and joints: therefore the correct determination of the shear strength is crucial. One of the most important parameters influencing the shear strength along rock joints is their surface roughness. Although the quantification of surface roughness has been an open question during the past century, several attempts have been made, starting with 2D and continuing with 3D measurements, to provide engineers with a method for determining shear strength numerically. As technology evolved, the 3D methods became more popular and several scientists started to investigate the surface properties through laser scanning and different photogrammetrical methods. This paper shows a photogrammetric method for the 3D digital recreation of joint surfaces of granitic rock and claystone, both potential host rocks for radioactive waste disposal. The rocks derived from Bátaapáti (South Hungary) and Mont Terri (North Switzerland) respectively. The samples are laboratory scaled specimens with an areal size of 50x50 mm. The software used is called ShapeMetrix3D, developed by 3GSM GmbH in Austria. The major steps of the creation of the 3D picture are presented, as well as the following data processing which leads to the quantification of the 3D surface roughness.

  10. The effects of surface gloss and roughness on color constancy for real 3-D objects.

    PubMed

    Granzier, Jeroen J M; Vergne, Romain; Gegenfurtner, Karl R

    2014-01-01

    Color constancy denotes the phenomenon that the appearance of an object remains fairly stable under changes in illumination and background color. Most of what we know about color constancy comes from experiments using flat, matte surfaces placed on a single plane under diffuse illumination simulated on a computer monitor. Here we investigate whether material properties (glossiness and roughness) have an effect on color constancy for real objects. Subjects matched the color and brightness of cylinders (painted red, green, or blue) illuminated by simulated daylight (D65) or by a reddish light with a Munsell color book illuminated by a tungsten lamp. The cylinders were either glossy or matte and either smooth or rough. The object was placed in front of a black background or a colored checkerboard. We found that color constancy was significantly higher for the glossy objects compared to the matte objects, and higher for the smooth objects compared to the rough objects. This was independent of the background. We conclude that material properties like glossiness and roughness can have significant effects on color constancy. PMID:24563527

  11. 3D shape measurements of fast moving rough surfaces by two tilted interference fringe systems

    NASA Astrophysics Data System (ADS)

    Kuschmierz, Robert; Günther, Philipp; Czarske, Jürgen W.

    2013-04-01

    Shape measurement of moving, especially rotating objects is an important task in the field of process control. The Laser Doppler Distance Sensor was invented for this purpose. It is realized by two tilted interference fringe systems and enables the simultaneous measurement of the surface velocity and profile. The distance is coded in the phase difference between the generated interference signals of two photo detectors. In order to achieve a distance uncertainty of below 1μm a steep calibration function is necessary. This can be achieved by increasing the tilting angle. However, due to the speckle effect at rough surfaces, random envelopes and phase jumps occur disturbing the phase difference estimation with increasing tilting angle. This problem was overcome recently by employing a receiving optics matching reducing the distance uncertainty by about one magnitude. By evaluating the Doppler frequencies of the two fringe systems the surface velocity and thereby the objects mean diameter can be calculated as well as angular misalignment of the sensor can be detected.

  12. Effect of a glaze/composite sealant on the 3-D surface roughness of esthetic restorative materials.

    PubMed

    Perez, Cesar dos Reis; Hirata, Raphael Júnior; da Silva, Antonio Henrique Monteiro da Fonseca Thomé; Sampaio, Eduardo Martins; de Miranda, Mauro Sayão

    2009-01-01

    The main goal of the current study was to evaluate the surface roughness of tooth-colored restorative materials after different finishing/polishing protocols, including a liquid polisher (BisCover, BISCO, Schaumburg, IL, USA). The restorative materials tested included two nanofilled resin composites (Filtek Supreme, 3M Dental Products, St Paul, MN, USA and Grandio, Voco, Cuxhaven, Germany), one resin-modified glass ionomer cement (Vitremer, 3M Dental Products) and one conventional glass ionomer cement (Meron Molar ART, Voco). The finishing/polishing methods were divided into five groups: G1 (compression with Mylar matrix), G2 (finishing with diamond burs), G3 (Sof-Lex, 3M Dental Products), G4 (BisCover, BISCO, after diamond burs) and G5 (BisCover after Sof-Lex). Five cylindrical specimens of each material were prepared for each group according to the manufacturer's instructions. The finishing/polishing methods were performed by a single operator in one direction to avoid variations at low speed (15,000 RPM). The surface roughness was evaluated using a 3-D scanning instrument with two parameters considered (Ra and Rz). The data was analyzed using one-way ANOVA followed by a multiple comparison Tukey's test. The results showed that BisCover (BISCO) was capable of reducing surface roughness and provided polished surfaces for all materials, enhancing smoothness over already polished surfaces (Sof-Lex, 3M Dental Products) and achieving polishing after finishing with diamond burs. PMID:19953776

  13. Fast Numerical Algorithms for 3-D Scattering from PEC and Dielectric Random Rough Surfaces in Microwave Remote Sensing

    NASA Astrophysics Data System (ADS)

    Zhang, Lisha

    We present fast and robust numerical algorithms for 3-D scattering from perfectly electrical conducting (PEC) and dielectric random rough surfaces in microwave remote sensing. The Coifman wavelets or Coiflets are employed to implement Galerkin's procedure in the method of moments (MoM). Due to the high-precision one-point quadrature, the Coiflets yield fast evaluations of the most off-diagonal entries, reducing the matrix fill effort from O(N2) to O( N). The orthogonality and Riesz basis of the Coiflets generate well conditioned impedance matrix, with rapid convergence for the conjugate gradient solver. The resulting impedance matrix is further sparsified by the matrix-formed standard fast wavelet transform (SFWT). By properly selecting multiresolution levels of the total transformation matrix, the solution precision can be enhanced while matrix sparsity and memory consumption have not been noticeably sacrificed. The unified fast scattering algorithm for dielectric random rough surfaces can asymptotically reduce to the PEC case when the loss tangent grows extremely large. Numerical results demonstrate that the reduced PEC model does not suffer from ill-posed problems. Compared with previous publications and laboratory measurements, good agreement is observed.

  14. Validation of the Cooray-Rubinstein (C-R) formula for a rough ground surface by using three-dimensional (3-D) FDTD

    NASA Astrophysics Data System (ADS)

    Li, Dongshuai; Zhang, Qilin; Liu, Tao; Wang, Zhenhui

    2013-11-01

    this paper, we have extended the Cooray-Rubinstein (C-R) approximate formula into the fractal rough ground surface and then validate its accuracy by using three-dimensional (3-D) finite-difference time-domain (FDTD) method at distances of 50 m and 100 m from the lightning channel. The results show that the extended C-R formula has an accepted accuracy for predicting the lightning-radiated horizontal electric field above the fractal rough and conducting ground, and its accuracy increases a little better with the higher of the earth conductivity. For instance, when the conductivity of the rough ground is 0.1 S/m, the error of the peak value predicted by the extended C-R formula is less than about 2.3%, while its error is less than about 6.7% for the conductivity of 0.01 S/m. The rough ground has much effect on the lightning horizontal field, and the initial peak value of the horizontal field obviously decreases with the increase of the root-mean-square height of the rough ground at early times (within several microseconds of the beginning of return stroke).

  15. Effect of Experimental Variables of Abrasive Wear on 3D Surface Roughness and Wear Rate of Al-4.5 % Cu Alloy

    NASA Astrophysics Data System (ADS)

    Ghosh, Debashis; Mallik, Manab; Mandal, Nilrudra; Dutta, Samik; Roy, Himadri; Lohar, Aditya Kumar

    2016-05-01

    This investigation was primarily carried out to examine the abrasive wear behavior of as cast Al-4.5 % Cu alloy. Wear tests have been carried out using an abrasive wear machine with emery paper embedded with SiC particles acting as abrasive medium. The experiments were planned using central composite design, with, load, cycle and grit size as input variables, whereas wear rate and 3D roughness were considered as output variable. Analysis of variance was applied to check the adequacy of the mathematical model and their respective parameters. Microstructural investigations of the worn surfaces have been carried out to explain the observed results and to understand the wear micro-mechanisms as per the planned experiments. Desirability function optimization technique was finally employed to optimize the controlling factors. The observed results revealed that, grit size plays a significant role in the variation of wear rate and 3D roughness as compared to load and cycles. Based on the significance of interactions, the regression equations were derived and verified further with a number of confirmation runs to assess the adequacy of the model. A close agreement (±10 %) between the predicted and experimentally measured results was obtained from this investigation.

  16. The impact of pore structure and surface roughness on capillary trapping for 2-D and 3-D porous media: Comparison with percolation theory

    NASA Astrophysics Data System (ADS)

    Geistlinger, Helmut; Ataei-Dadavi, Iman; Mohammadian, Sadjad; Vogel, Hans-Jörg

    2015-11-01

    We study the impact of pore structure and surface roughness on capillary trapping of nonwetting gas phase during imbibition with water for capillary numbers between 10-7 and 5 × 10-5, within glass beads, natural sands, glass beads monolayers, and 2-D micromodels. The materials exhibit different roughness of the pore-solid interface. We found that glass beads and natural sands, which exhibit nearly the same grain size distribution, pore size distribution, and connectivity, showed a significant difference of the trapped gas phase of about 15%. This difference can be explained by the microstructure of the pore-solid interface. Based on the visualization of the trapping dynamics within glass beads monolayers and 2-D micromodels, we could show that bypass trapping controls the trapping process in glass beads monolayers, while snap-off trapping controls the trapping process in 2-D micromodels. We conclude that these different trapping processes are the reason for the different trapping efficiency, when comparing glass beads packs with natural sand packs. Moreover, for small capillary numbers of 10-6, we found that the cluster size distribution of trapped gas clusters of all 2-D and 3-D porous media can be described by a universal power law behavior predicted from percolation theory. This cannot be expected a priori for 2-D porous media, because bicontinuity of the two bulk phases is violated. Obviously, bicontinuity holds for the thin-film water phase and the bulk gas phase. The snap-off trapping process leads to ordinary bond percolation in front of the advancing bulk water phase and is the reason for the observed universal power law behavior in 2-D micromodels with rough surfaces.

  17. Scattering of near normal incidence SH waves by sinusoidal and rough surfaces in 3-D: comparison to the scalar wave approximation.

    PubMed

    Jarvis, Andrew J C; Cegla, Frederic B

    2014-07-01

    The challenge of accurately simulating how incident scalar waves interact with rough boundaries has made it an important area of research within many scientific disciplines. Conventional methods, which in the majority of cases focus only on scattering in two dimensions, often suffer from long simulation times or reduced accuracy, neglecting phenomena such as multiple scattering and surface self-shadowing. A simulation based on the scalar wave distributed point source method (DPSM) is presented as an alternative which is computationally more efficient than fully meshed numerical methods while obtaining greater accuracy than approximate analytical techniques. Comparison is made to simulated results obtained using the finite element method for a sinusoidally periodic surface where scattering only occurs in two dimensions, showing very good agreement (<0.2 dB). In addition to two-dimensional scattering, comparison to experimental results is also carried out for scattering in three dimensions when the surface has a Gaussian roughness distribution. Results indicate that for two-dimensional scattering and for rough surfaces with a correlation length equal to the incident wavelength (λ) and a root mean square height less than 0.2λ, the scalar wave approximation predicts reflected pulse shape change and envelope amplitudes generally to within 1 dB. Comparison between transducers within a three-element array also illustrate the sensitivity pulse amplitude can have to sensor position above a rough surface, differing by as much as 17 dB with a positional change of just 1.25λ. PMID:24960707

  18. Rough surface effects on active and passive microwave remote sensing of soil moisture at L-band using 3D fast solution of Maxwell's equations

    NASA Astrophysics Data System (ADS)

    Wang, Haogang; Liao, Tien-Hao; Shi, Jiancheng; Yu, Zherui

    2014-11-01

    The forthcoming Water Cycle Observation Mission (WCOM) is to understand the water cycle system among land, atmosphere, and ocean. In both active and passive microwave remote sensing of soil moisture, the surface roughness plays an important role. Electromagnetic models of roughness provide tables of emissivities and backscattering coefficients that can be used to retrieve soil moisture. In this paper, a fast and accurate three dimensional solution of Maxwell's equations is developed and employed to solve rough soil surface scattering problem at L-band. The algorithm combines QR Pre-Ranked Multilevel UV(MLUV) factorization and Hierarchical Fast Far Field Approximation. It is implemented using OpenMP interface for fast parallel calculation. In this algorithm, 1) QR based rank predetermined algorithm is derived to further compress the UV matrix pairs obtained using coarse-coarse sampling; 2) at the finer levels, MLUV is used straightforwardly to factorize the interactions between groups, while at the coarsest level, interactions between groups in the interaction list are calculated using an elegantly derived Hierarchical Fast Far Field Approximation (HFAFFA) to accelerate the calculation of interactions between large groups while keeping the accuracy of this approximation; 3) OpenMP interface is used to parallelize this new algorithm. Numerical results including the incoherent bistatic scattering coefficients and the emissivity demonstrate the efficiency of this method.

  19. Recognition methods for 3D textured surfaces

    NASA Astrophysics Data System (ADS)

    Cula, Oana G.; Dana, Kristin J.

    2001-06-01

    Texture as a surface representation is the subject of a wide body of computer vision and computer graphics literature. While texture is always associated with a form of repetition in the image, the repeating quantity may vary. The texture may be a color or albedo variation as in a checkerboard, a paisley print or zebra stripes. Very often in real-world scenes, texture is instead due to a surface height variation, e.g. pebbles, gravel, foliage and any rough surface. Such surfaces are referred to here as 3D textured surfaces. Standard texture recognition algorithms are not appropriate for 3D textured surfaces because the appearance of these surfaces changes in a complex manner with viewing direction and illumination direction. Recent methods have been developed for recognition of 3D textured surfaces using a database of surfaces observed under varied imaging parameters. One of these methods is based on 3D textons obtained using K-means clustering of multiscale feature vectors. Another method uses eigen-analysis originally developed for appearance-based object recognition. In this work we develop a hybrid approach that employs both feature grouping and dimensionality reduction. The method is tested using the Columbia-Utrecht texture database and provides excellent recognition rates. The method is compared with existing recognition methods for 3D textured surfaces. A direct comparison is facilitated by empirical recognition rates from the same texture data set. The current method has key advantages over existing methods including requiring less prior information on both the training and novel images.

  20. Estimating surface roughness using stereophotogrammetry

    NASA Astrophysics Data System (ADS)

    David, V.; Krasa, J.

    2009-04-01

    At the Department of Drainage, Irrigation and Landscape Engineering (CTU Prague) we use several mathematical models for soil erosion, sediment transport and surface runoff assessment. Here we continuously struggle for successful models parameterizations. One of the typical coefficients usually taken from literature instead of measurements is surface roughness, eg. Manning roughness (Maidment, 1993). Roughness is a key to surface runoff velocity and surface runoff depth estimation but often it is very roughly estimated. Within the COST 22 Action research we focused on estimating actual surface roughness using stereophotogrammetry. Our aim was to set up a simple low cost system useful for roughness measurements in nature conditions - mainly on agricultural fields. Our system consists of Canon EOS 400 digital camera with angle viewfinder, two robust tripods and a horizontal bar with sliding 3D tripod head. We tested different camera heights and focal distances as well as various parallaxes to obtain reasonable results. Finally we shot the surfaces from 1600 millimeters with 24 and 35 mm lens and parallaxes close to 100 mm. For 3D scene development we use Geomatica 10 GIS and its OrthoEngine module. Testing the proper system and many variables of the 3D scene modelling was an important part of the first year of the project. For these purposes we first prepared a calibrated and known 3D surface consisting of 70 by 70 cm grid and several geometrical objects of different sizes and shapes. Preparing the correct lighting conditions, finding the resolving power of the system and solving the problems with low contrast areas of measured surfaces was a time consuming but interesting task. After the system calibration we started with the actual terrain measurements. Our setup, system testing and preliminary results of the roughness computations are presented on the poster. Acknowledgement This research was acomplished within national COST project OC189 „Flood risk and its

  1. Additively Manufactured 3D Porous Ti-6Al-4V Constructs Mimic Trabecular Bone Structure and Regulate Osteoblast Proliferation, Differentiation and Local Factor Production in a Porosity and Surface Roughness Dependent Manner

    PubMed Central

    Cheng, Alice; Humayun, Aiza; Cohen, David J.; Boyan, Barbara D.; Schwartz, Zvi

    2014-01-01

    Additive manufacturing by laser sintering is able to produce high resolution metal constructs for orthopaedic and dental implants. In this study, we used a human trabecular bone template to design and manufacture Ti-6Al-4V constructs with varying porosity via laser sintering. Characterization of constructs revealed interconnected porosities ranging from 15–70% with compressive moduli of 2063–2954 MPa. These constructs with macro porosity were further surface-treated to create a desirable multi-scale micro-/nano-roughness, which has been shown to enhance the osseointegration process. Osteoblasts (MG63 cells) exhibited high viability when grown on the constructs. Proliferation (DNA) and alkaline phosphatase specific activity (ALP), an early differentiation marker, decreased as porosity increased, while osteocalcin (OCN), a late differentiation marker, as well as osteoprotegerin (OPG), vascular endothelial growth factor (VEGF) and bone morphogenetic proteins 2 and 4 (BMP2, BMP4) increased with increasing porosity. 3D constructs with the highest porosity and surface modification supported the greatest osteoblast differentiation and local factor production. These results indicate that additively manufactured 3D porous constructs mimicking human trabecular bone and produced with additional surface treatment can be customized for increased osteoblast response. Increased factors for osteoblast maturation and differentiation on high porosity constructs suggest the enhanced performance of these surfaces for increasing osseointegration in vivo. PMID:25287305

  2. 3D versus 2D domain wall interaction in ideal and rough nanowires

    NASA Astrophysics Data System (ADS)

    Pivano, A.; Dolocan, Voicu O.

    2015-11-01

    The interaction between transverse magnetic domain walls (TDWs) in planar (2D) and cylindrical (3D) nanowires is examined using micromagnetic simulations. We show that in perfect and surface deformed wires the free TDWs behave differently, as the 3D TDWs combine into metastable states with average lifetimes of 300 ns depending on roughness, while the 2D TDWs do not due to 2D shape anisotropy. When the 2D and 3D TDWs are pinned at artificial constrictions, they behave similarly as they interact mainly through the dipolar field. This magnetostatic interaction is well described by the point charge model with multipole expansion. In surface deformed wires with artificial constrictions, the interaction becomes more complex as the depinning field decreases and dynamical pinning can lead to local resonances. This can strongly influence the control of TDWs in DW-based devices.

  3. Virtual rough samples to test 3D nanometer-scale scanning electron microscopy stereo photogrammetry

    NASA Astrophysics Data System (ADS)

    Villarrubia, J. S.; Tondare, V. N.; Vladár, A. E.

    2016-03-01

    The combination of scanning electron microscopy for high spatial resolution, images from multiple angles to provide 3D information, and commercially available stereo photogrammetry software for 3D reconstruction offers promise for nanometer-scale dimensional metrology in 3D. A method is described to test 3D photogrammetry software by the use of virtual samples—mathematical samples from which simulated images are made for use as inputs to the software under test. The virtual sample is constructed by wrapping a rough skin with any desired power spectral density around a smooth near-trapezoidal line with rounded top corners. Reconstruction is performed with images simulated from different angular viewpoints. The software's reconstructed 3D model is then compared to the known geometry of the virtual sample. Three commercial photogrammetry software packages were tested. Two of them produced results for line height and width that were within close to 1 nm of the correct values. All of the packages exhibited some difficulty in reconstructing details of the surface roughness.

  4. Random rough surface photofabrication

    NASA Astrophysics Data System (ADS)

    Brissonneau, Vincent; Escoubas, Ludovic; Flory, François; Berginc, Gérard

    2011-10-01

    Random rough surfaces are of primary interest for their optical properties: reducing reflection at the interface or obtaining specific scattering diagram for example. Thus controlling surface statistics during the fabrication process paves the way to original and specific behaviors of reflected optical waves. We detail an experimental method allowing the fabrication of random rough surfaces showing tuned statistical properties. A two-step photoresist exposure process was developed. In order to initiate photoresist polymerization, an energy threshold needs to be reached by light exposure. This energy is brought by a uniform exposure equipment comprising UV-LEDs. This pre-exposure is studied by varying parameters such as optical power and exposure time. The second step consists in an exposure based on the Gray method.1 The speckle pattern of an enlarged scattered laser beam is used to insolate the photoresist. A specific photofabrication bench using an argon ion laser was implemented. Parameters such as exposure time and distances between optical components are discussed. Then, we describe how we modify the speckle-based exposure bench to include a spatial light modulator (SLM). The SLM used is a micromirror matrix known as Digital Micromirror Device (DMD) which allows spatial modulation by displaying binary images. Thus, the spatial beam shape can be tuned and so the speckle pattern on the photoresist is modified. As the photoresist photofabricated surface is correlated to the speckle pattern used to insolate, the roughness parameters can be adjusted.

  5. Nonlaser-based 3D surface imaging

    SciTech Connect

    Lu, Shin-yee; Johnson, R.K.; Sherwood, R.J.

    1994-11-15

    3D surface imaging refers to methods that generate a 3D surface representation of objects of a scene under viewing. Laser-based 3D surface imaging systems are commonly used in manufacturing, robotics and biomedical research. Although laser-based systems provide satisfactory solutions for most applications, there are situations where non laser-based approaches are preferred. The issues that make alternative methods sometimes more attractive are: (1) real-time data capturing, (2) eye-safety, (3) portability, and (4) work distance. The focus of this presentation is on generating a 3D surface from multiple 2D projected images using CCD cameras, without a laser light source. Two methods are presented: stereo vision and depth-from-focus. Their applications are described.

  6. Methods for comparing 3D surface attributes

    NASA Astrophysics Data System (ADS)

    Pang, Alex; Freeman, Adam

    1996-03-01

    A common task in data analysis is to compare two or more sets of data, statistics, presentations, etc. A predominant method in use is side-by-side visual comparison of images. While straightforward, it burdens the user with the task of discerning the differences between the two images. The user if further taxed when the images are of 3D scenes. This paper presents several methods for analyzing the extent, magnitude, and manner in which surfaces in 3D differ in their attributes. The surface geometry are assumed to be identical and only the surface attributes (color, texture, etc.) are variable. As a case in point, we examine the differences obtained when a 3D scene is rendered progressively using radiosity with different form factor calculation methods. The comparison methods include extensions of simple methods such as mapping difference information to color or transparency, and more recent methods including the use of surface texture, perturbation, and adaptive placements of error glyphs.

  7. 3D-patterned polymer brush surfaces

    NASA Astrophysics Data System (ADS)

    Zhou, Xuechang; Liu, Xuqing; Xie, Zhuang; Zheng, Zijian

    2011-12-01

    Polymer brush-based three-dimensional (3D) structures are emerging as a powerful platform to engineer a surface by providing abundant spatially distributed chemical and physical properties. In this feature article, we aim to give a summary of the recent progress on the fabrication of 3D structures with polymer brushes, with a particular focus on the micro- and nanoscale. We start with a brief introduction on polymer brushes and the challenges to prepare their 3D structures. Then, we highlight the recent advances of the fabrication approaches on the basis of traditional polymerization time and grafting density strategies, and a recently developed feature density strategy. Finally, we provide some perspective outlooks on the future directions of engineering the 3D structures with polymer brushes.

  8. Stylolite shape, roughness growth dynamics and related burial history: a 3D analysis.

    NASA Astrophysics Data System (ADS)

    Beaudoin, Nicolas; Koehn, Daniel

    2016-04-01

    Stylolites are dissolution features that develop under applied pressure and during chemical compaction. Stylolites are common in sedimentary basin, altering the chemistry and physical properties of rocks, as well as the small- to large-scale hydrological system. This contribution follows recent finding about the self-affine roughness growth properties leading to a fractal, stitch-like shape of stylolites. 3D surface scanning and X-ray computed microtomography imaging have been carried out onto numerous stylolites from the southern Permian Zechstein basin (Germany) and from the Umbria Marches fold-and-thrust belts (Italy). In these two environments stylolites have been sorted following a recent advanced classification of stylolite based on the shape and growth dynamics. This classification consists in four classes (rectangular layer type, seismogram pinning type suture/sharp peak type and simple wave-like type) and we aim to characterize the roughness properties for each of these classes. A fractal analysis has been conducted accordingly using Fourier transform and Correlation function signal analysis over roughness surfaces. These fractal analyses have been used to reconstruct the maximum burial depth recorded by each stylolite. The reconstruction of burial depths at the same place but regarding all stylolite classes returns and maximum depth evolution. This dataset is thus used 1- to understand the links between the roughness growth dynamics of stylolites and their final shape and 2- to establish a relationship linking the shape of roughness to the maximum burial depth recorded. We hope results and interpretation reported can push the community to consider stylolite as an efficient tool and reliable way to appraise burial history in sedimentary basins.

  9. Solvation forces between rough surfaces

    SciTech Connect

    Frink, L.J.; van Swol, F.

    1998-04-01

    We investigate the role of surface roughness on solvation forces and solvation free energies. Roughness is introduced by dividing a surface into an array of square tiles that are then randomly displaced in the direction perpendicular to the wall. The integrated wall strength of these tiled surfaces is independent of the surface roughness and hence this class of rough walls is ideally suited for isolating roughness effects. We use grand canonical Monte Carlo simulations of a Lennard-Jones fluid confined in a slit pore with rough walls to generate the solvation interactions as a function of roughness, tile size, and surface area. The simulation data are compared to a simple superposition approximation of smooth wall solvation interactions (obtained from simulation or density functional theory), based on a distribution of wall separations. We find that this approximation provides a surprisingly accurate route to the solvation interaction of rough surfaces. In general, increased roughness leads to a reduction of oscillations in the solvation forces and surface free energies. However, nonmonotonic behavior of the oscillation amplitude with roughness can be observed for finite surfaces. The washing out of the oscillations found for large surface roughness produces a solvation force that exhibits a broad repulsive peak with separation. The broad repulsion is a consequence of the resistance to squeezing out fluid from the smallest gaps between two opposing rough surfaces. It is as much a reflection of packing effects as are the solvation oscillations for perfectly smooth pores. In addition, we present results for patterned and undulating surfaces produced by an analogous modification of the one-body external field for smooth walls. Finally, we discuss the implications of our results for a number of experimental systems including self-assembled monolayers, microporous materials, protein solutions, and DNA crystals. {copyright} {ital 1998 American Institute of Physics.}

  10. Quantifying bone weathering stages using the average roughness parameter Ra measured from 3D data

    NASA Astrophysics Data System (ADS)

    Vietti, Laura A.

    2016-09-01

    Bone surface texture is known to degrade in a predictable fashion due to subaerial exposure, and can thus act as a relative proxy for estimating temporal information from modern and ancient bone assemblages. To date, the majority of bone weathering data is collected on a categorical scale based on descriptive terms. While this qualitative classification of weathering data is well established, textural analyses of bone surfaces may provide means to quantify weathering stages but have yet to be tested. Here, I examined the suitability of textural analyses for bone weathering studies by first establishing bone surface regions most appropriate for weathering analyses. I then measured and compared the roughness texture of weathered bones at different stages. To establish regions of bone most suitable for textural analyses, Ra was measured from 3D scans of dorsal ribs of four adult ungulate taxa. Results indicate that the rib-shafts from unweathered ungulate skeletons were similar and are likely good candidates because differences in surface texture will not be due to differences in initial bone texture. To test if textural measurements could reliably characterize weathering stages, the average roughness values (Ra) were measured from weathered ungulate rib-shafts assigned to four descriptive weathering stages. Results from analyses indicate that the Ra was statistically distinct for each weathering stage and that roughness positively correlates with the degree of weathering. As such, results suggest that textural analyses may provide the means for quantifying bone-weathering stages. Using Ra and other quantifiable texture parameters may enable more reliable and comparative taphonomic analyses by reducing inter-observer variations and by providing numerical data more compatible for multivariate statistics.

  11. Does surface roughness amplify wetting?

    SciTech Connect

    Malijevský, Alexandr

    2014-11-14

    Any solid surface is intrinsically rough on the microscopic scale. In this paper, we study the effect of this roughness on the wetting properties of hydrophilic substrates. Macroscopic arguments, such as those leading to the well-known Wenzel's law, predict that surface roughness should amplify the wetting properties of such adsorbents. We use a fundamental measure density functional theory to demonstrate the opposite effect from roughness for microscopically corrugated surfaces, i.e., wetting is hindered. Based on three independent analyses we show that microscopic surface corrugation increases the wetting temperature or even makes the surface hydrophobic. Since for macroscopically corrugated surfaces the solid texture does indeed amplify wetting there must exist a crossover between two length-scale regimes that are distinguished by opposite response on surface roughening. This demonstrates how deceptive can be efforts to extend the thermodynamical laws beyond their macroscopic territory.

  12. Roughness reduction on aspheric surfaces

    NASA Astrophysics Data System (ADS)

    Kiontke, S.; Kokot, Sebastian

    2015-02-01

    For a lot of applications like spectrometer and high power laser roughness as an important parameter has been discussed over and over again. Especially for high power systems the surface quality is crucial for determining the damage threshold and therefore the field of application. Above that, it has often been difficult to compare roughness measurements because of different measurement methods and the usage of filters and surface fits. Measurement results differ significantly depending on filters and especially on the measured surface size. Insights will be given how values behave depending on the quality of surface and the size of measured area. Many applications require a high quality of roughness in order to reduce scattering. Some of them in order to prevent from damage like high power laser applications. Others like spectrometers seek to increase the signal-to-noise ratio. Most of them have already been built with spherical surfaces. With higher demands on efficiency and more sophisticated versions aspherical surfaces need to be employed. Therefore, the high requirement in roughness known from spherical surfaces is also needed on aspherical surfaces. For one thing, the constant change of curvature of an aspherical surface accounts for the superior performance, for another thing, it prevents from using classical polishing technics, which guarantied this low roughness. New methods need to be qualified. In addition, also results of a new manufacturing process will be shown allowing low roughness on aspheric even with remarkable departure from the best fit sphere.

  13. PLOT3D- DRAWING THREE DIMENSIONAL SURFACES

    NASA Technical Reports Server (NTRS)

    Canright, R. B.

    1994-01-01

    PLOT3D is a package of programs to draw three-dimensional surfaces of the form z = f(x,y). The function f and the boundary values for x and y are the input to PLOT3D. The surface thus defined may be drawn after arbitrary rotations. However, it is designed to draw only functions in rectangular coordinates expressed explicitly in the above form. It cannot, for example, draw a sphere. Output is by off-line incremental plotter or online microfilm recorder. This package, unlike other packages, will plot any function of the form z = f(x,y) and portrays continuous and bounded functions of two independent variables. With curve fitting; however, it can draw experimental data and pictures which cannot be expressed in the above form. The method used is division into a uniform rectangular grid of the given x and y ranges. The values of the supplied function at the grid points (x, y) are calculated and stored; this defines the surface. The surface is portrayed by connecting successive (y,z) points with straight-line segments for each x value on the grid and, in turn, connecting successive (x,z) points for each fixed y value on the grid. These lines are then projected by parallel projection onto the fixed yz-plane for plotting. This program has been implemented on the IBM 360/67 with on-line CDC microfilm recorder.

  14. Surface Plasmons in 3D Topological Insulators

    NASA Astrophysics Data System (ADS)

    Kogar, Anshul; Vig, Sean; Cho, Gil; Thaler, Alexander; Xiao, Yiran; Hughes, Taylor; Wong, Man-Hong; Chiang, Tai-Chang; MacDougall, Greg; Abbamonte, Peter

    2015-03-01

    Most studies of three-dimensional (3D) topological insulators have concentrated on their one-electron properties as exhibited by angle-resolved photoemission spectroscopy (ARPES) or by scanning tunneling microscopy (STM). Many-body interactions are often neglected in the treatment of models of topological insulators, such as in the Kane-Mele and Bernevig-Hughes-Zhang models. Using angle-resolved inelastic electron scattering from the surface, I will present data on the collective mode that owes its existence to the presence of many-body interactions, the surface plasmon (SP), in two known 3D topological insulators, Bi2Se3 and Bi0.5Sb1.5Se1 . 5 + xTe1 . 5 - x. Surprisingly, the SP was prominent even after depressing the Fermi energy into the bulk band gap. Having studied the SP as a function of doping, momentum transfer and its aging properties, I will present evidence to suggest that bulk-surface coupling is crucial in explaining many of its properties. A simple model with dynamic bulk screening will be presented showing qualitative agreement with the observations. Lastly, the relation of the observed surface plasmon to the predicted spin-plasmon mode and to the kinks seen in the electronic dispersion as measured by ARPES will be discussed. The work was supported as part of the Center for Emergent Superconductivity, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science.

  15. Measuring Roughnesses Of Optical Surfaces

    NASA Technical Reports Server (NTRS)

    Coulter, Daniel R.; Al-Jumaily, Gahnim A.; Raouf, Nasrat A.; Anderson, Mark S.

    1994-01-01

    Report discusses use of scanning tunneling microscopy and atomic force microscopy to measure roughnesses of optical surfaces. These techniques offer greater spatial resolution than other techniques. Report notes scanning tunneling microscopes and atomic force microscopes resolve down to 1 nm.

  16. 3D surface defect analysis and evaluation

    NASA Astrophysics Data System (ADS)

    Yang, B.; Jia, M.; Song, G. J.; Tao, L.; Harding, K. G.

    2008-08-01

    A method is proposed for surface defect analysis and evaluation. Good 3D point clouds can now be obtained through a variety of surface profiling methods such as stylus tracers, structured light, or interferometry. In order to inspect a surface for defects, first a reference surface that represents the surface without any defects needs to be identified. This reference surface can then be fit to the point cloud. The algorithm we present finds the least square solution for the overdetermined equation set to obtain the parameters of the reference surface mathematical description. The distance between each point within the point cloud and the reference surface is then calculated using to the derived reference surface equation. For analysis of the data, the user can preset a threshold distance value. If the calculated distance is bigger than the threshold value, the corresponding point is marked as a defect point. The software then generates a color-coded map of the measured surface. Defect points that are connected together are formed into a defect-clustering domain. Each defect-clustering domain is treated as one defect area. We then use a clustering domain searching algorithm to auto-search all the defect areas in the point cloud. The different critical parameters used for evaluating the defect status of a point cloud that can be calculated are described as: P-Depth,a peak depth of all defects; Defect Number, the number of surface defects; Defects/Area, the defect number in unit area; and Defect Coverage Ratio which is a ratio of the defect area to the region of interest.

  17. Nanowetting of rough superhydrophobic surfaces

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Lamb, R. N.; Cookson, D. J.

    2007-12-01

    Small angle x-ray scattering has been used to investigate the in situ immersive wetting of ultrarough surfaces which exhibit superhydrophobicity with extreme water contact angle (θA=169°). Reduced scattering contrast observed from rough surfaces when partially or totally wetted reveals significant physical differences between superhydrophobic surfaces not otherwise apparent from conventional contact angle measurements.

  18. Polymer Transport Near Rough Surfaces

    NASA Astrophysics Data System (ADS)

    Bloom, Moses; Whitmer, Jonathan; Luijten, Erik

    2011-03-01

    The rheology of dilute polymer solutions under confinement is important in biology, medicine, microfluidic device design, synthetic polymer processing, and even geologic porous media. However, the solution's specific interactions with the confining surface are poorly understood. This situation is exacerbated for composite nanoparticles, such as polymer/metallic hybrids. Using multi-particle collision dynamics, we find a rich array of transport regimes depending on small-scale surface roughness and the specific surface/solute interactions. These factors couple to hydrodynamic conditions, including flow strength and confinement geometry in unexpected ways. Our findings may be relevant to transport phenomena in certain rough-walled capillaries, such as the distribution of various nanoconjugates in vivo.

  19. 3D Surface Reconstruction and Automatic Camera Calibration

    NASA Technical Reports Server (NTRS)

    Jalobeanu, Andre

    2004-01-01

    Illustrations in this view-graph presentation are presented on a Bayesian approach to 3D surface reconstruction and camera calibration.Existing methods, surface analysis and modeling,preliminary surface reconstruction results, and potential applications are addressed.

  20. Flow transition with 2-D roughness elements in a 3-D channel

    NASA Technical Reports Server (NTRS)

    Liu, Zhining; Liu, Chaoquin; Mccormick, Stephen F.

    1993-01-01

    We develop a new numerical approach to study the spatially evolving instability of the streamwise dominant flow in the presence of roughness elements. The difficulty in handling the flow over the boundary surface with general geometry is removed by using a new conservative form of the governing equations and an analytical mapping. The numerical scheme uses second-order backward Euler in time, fourth-order central differences in all three spatial directions, and boundary-fitted staggered grids. A three-dimensional channel with multiple two-dimensional-type roughness elements is employed as the test case. Fourier analysis is used to decompose different Fourier modes of the disturbance. The results show that surface roughness leads to transition at lower Reynolds number than for smooth channels.

  1. S3D: An interactive surface grid generation tool

    NASA Technical Reports Server (NTRS)

    Luh, Raymond Ching-Chung; Pierce, Lawrence E.; Yip, David

    1992-01-01

    S3D, an interactive software tool for surface grid generation, is described. S3D provides the means with which a geometry definition based either on a discretized curve set or a rectangular set can be quickly processed towards the generation of a surface grid for computational fluid dynamics (CFD) applications. This is made possible as a result of implementing commonly encountered surface gridding tasks in an environment with a highly efficient and user friendly graphical interface. Some of the more advanced features of S3D include surface-surface intersections, optimized surface domain decomposition and recomposition, and automated propagation of edge distributions to surrounding grids.

  2. Calibration of surface roughness standards

    NASA Astrophysics Data System (ADS)

    Thalmann, R.; Nicolet, A.; Meli, F.; Picotto, G. B.; Matus, M.; Carcedo, L.; Hemming, B.; Ganioglu, O.; De Chiffre, L.; Saraiva, F.; Bergstrand, S.; Zelenika, S.; Tonmueanwai, A.; Tsai, C.-L.; Shihua, W.; Kruger, O.; de Souza, M. M.; Salgado, J. A.; Ramotowski, Z.

    2016-01-01

    The key comparison EURAMET.L-K8.2013 on roughness was carried out in the framework of a EURAMET project starting in 2013 and ending in 2015. It involved the participation of 17 National Metrology Institutes from Europe, Asia, South America and Africa representing four regional metrology organisations. Five surface texture standards of different type were circulated and on each of the standards several roughness parameters according to the standard ISO 4287 had to be determined. 32 out of 395 individual results were not consistent with the reference value. After some corrective actions the number of inconsistent results could be reduced to 20, which correspond to about 5% of the total and can statistically be expected. In addition to the material standards, two softgauges were circulated, which allow to test the software of the instruments used in the comparison. The comparison results help to support the calibraton and measurement capabilities (CMCs) of the laboratories involved in the CIPM MRA. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  3. Electroosmotic flow through a microparallel channel with 3D wall roughness.

    PubMed

    Chang, Long; Jian, Yongjun; Buren, Mandula; Sun, Yanjun

    2016-02-01

    In this paper, a perturbation method is introduced to study the EOF in a microparallel channel with 3D wall roughness. The corrugations of the two walls are periodic sinusoidal waves of small amplitude in two directions either in phase or half-period out of phase. Based on linearized Poisson-Boltzmann equation, Laplace equation, and the Navier-Stokes equations, the perturbation solutions of velocity, electrical potential, and volume flow rate are obtained. By using numerical computation, the influences of the wall corrugations on the mean velocity are analyzed. The variations of electrical potential, velocity profile, mean velocity, and their dependences on the wave number α and β of wall corrugations in two directions, the nondimensional electrokinetic width K, and the zeta potential ratio between the lower wall and the upper wall ς are analyzed graphically. PMID:26333852

  4. Cell Proliferation on Macro/Nano Surface Structure and Collagen Immobilization of 3D Polycaprolactone Scaffolds.

    PubMed

    Park, Young-Ouk; Myung, Sung-Woon; Kook, Min-Suk; Jung, Sang-Chul; Kim, Byung-Hoon

    2016-02-01

    In this study, 3D polycaprolactone (PCL) scaffolds were fabricated by 3D printing technique. The macro/nano morphology of, 3D PCL scaffolds surface was etched with oxygen plasma. Acrylic acid (AA) plasma-polymerization was performed to functionalize the macro/nano surface with carboxyl groups and then collagen was immobilized with plasma-polymerized 3D PCL scaffolds. After O2 plasma and AA plasma-polymerization, contact angles were decreased. The FE-SEM and AFM results showed that O2 plasma is increased the surface roughness. The MTT assay results showed that proliferation of the M3CT3-E1 cells increased on the oxygen plasma treated and collagen immobilized 3D PCL scaffolds. PMID:27433597

  5. Martian surface roughness and stratigraphy

    NASA Astrophysics Data System (ADS)

    Beyer, Ross Alan

    2004-12-01

    Orbital datasets can be combined and manipulated to learn about the three- dimensional structure of planetary surfaces, and the processes that have acted on them. The Mars Orbital Camera (MOC) is providing high-resolution images. These images allow qualitative inspection of features, and contain quantitative information about the shape of the surface. Using a photoclinometry technique derived from a lunar-Lambert photometric function, I am able to obtain estimates of the down-sun slope of each pixel in an image. This technique was calibrated against synthetic topography, compared to an area photoclinometry technique, and applied to the Viking and Pathfinder landing sites. It is a robust technique for obtaining the roughness and slope characteristics of large areas. It was applied to the potential landing sites for the Mars Exploration Rovers to evaluate site safety. The slopes from this point photoclinometry technique can be used to obtain a rough estimate of topography, which I used in a number of studies where topographic information was crucial. MOC images have shown that layering is pervasive on the martian surface. Mars Orbital Laser Altimeter (MOLA) data can be registered to MOC images to provide elevation constraints on layer outcrops. Such layers are observed in eastern Coprates Chasma both in the chasma rim and in a flat-topped massif. Observations indicate that the chasma stratigraphy consists of thin sequences of resistant layers and intervening thicker sequences of relatively less resistant layers. More resistant units cap the massif against erosion and result in steeper slopes than the weaker units would otherwise allow. These resistant layers can be used as stratigraphic markers which have allowed me to measure the subsidence and tilting of the massif relative to the chasma walls, providing evidence for tectonic motion in this portion of the Valles Marineris. These outcrops indicate that some of these layers may be analogus to terristrial flood

  6. Wetting properties of molecularly rough surfaces

    SciTech Connect

    Svoboda, Martin; Lísal, Martin; Malijevský, Alexandr

    2015-09-14

    We employ molecular dynamics simulations to study the wettability of nanoscale rough surfaces in systems governed by Lennard-Jones (LJ) interactions. We consider both smooth and molecularly rough planar surfaces. Solid substrates are modeled as a static collection of LJ particles arranged in a face-centered cubic lattice with the (100) surface exposed to the LJ fluid. Molecularly rough solid surfaces are prepared by removing several strips of LJ atoms from the external layers of the substrate, i.e., forming parallel nanogrooves on the surface. We vary the solid-fluid interactions to investigate strongly and weakly wettable surfaces. We determine the wetting properties by measuring the equilibrium droplet profiles that are in turn used to evaluate the contact angles. Macroscopic arguments, such as those leading to Wenzel’s law, suggest that surface roughness always amplifies the wetting properties of a lyophilic surface. However, our results indicate the opposite effect from roughness for microscopically corrugated surfaces, i.e., surface roughness deteriorates the substrate wettability. Adding the roughness to a strongly wettable surface shrinks the surface area wet with the liquid, and it either increases or only marginally affects the contact angle, depending on the degree of liquid adsorption into the nanogrooves. For a weakly wettable surface, the roughness changes the surface character from lyophilic to lyophobic due to a weakening of the solid-fluid interactions by the presence of the nanogrooves and the weaker adsorption of the liquid into the nanogrooves.

  7. Wetting properties of molecularly rough surfaces.

    PubMed

    Svoboda, Martin; Malijevský, Alexandr; Lísal, Martin

    2015-09-14

    We employ molecular dynamics simulations to study the wettability of nanoscale rough surfaces in systems governed by Lennard-Jones (LJ) interactions. We consider both smooth and molecularly rough planar surfaces. Solid substrates are modeled as a static collection of LJ particles arranged in a face-centered cubic lattice with the (100) surface exposed to the LJ fluid. Molecularly rough solid surfaces are prepared by removing several strips of LJ atoms from the external layers of the substrate, i.e., forming parallel nanogrooves on the surface. We vary the solid-fluid interactions to investigate strongly and weakly wettable surfaces. We determine the wetting properties by measuring the equilibrium droplet profiles that are in turn used to evaluate the contact angles. Macroscopic arguments, such as those leading to Wenzel's law, suggest that surface roughness always amplifies the wetting properties of a lyophilic surface. However, our results indicate the opposite effect from roughness for microscopically corrugated surfaces, i.e., surface roughness deteriorates the substrate wettability. Adding the roughness to a strongly wettable surface shrinks the surface area wet with the liquid, and it either increases or only marginally affects the contact angle, depending on the degree of liquid adsorption into the nanogrooves. For a weakly wettable surface, the roughness changes the surface character from lyophilic to lyophobic due to a weakening of the solid-fluid interactions by the presence of the nanogrooves and the weaker adsorption of the liquid into the nanogrooves. PMID:26374050

  8. Target surface finding using 3D SAR data

    NASA Astrophysics Data System (ADS)

    Ruiter, Jason R.; Burns, Joseph W.; Subotic, Nikola S.

    2005-05-01

    Methods of generating more literal, easily interpretable imagery from 3-D SAR data are being studied to provide all weather, near-visual target identification and/or scene interpretation. One method of approaching this problem is to automatically generate shape-based geometric renderings from the SAR data. In this paper we describe the application of the Marching Tetrahedrons surface finding algorithm to 3-D SAR data. The Marching Tetrahedrons algorithm finds a surface through the 3-D data cube, which provides a recognizable representation of the target surface. This algorithm was applied to the public-release X-patch simulations of a backhoe, which provided densely sampled 3-D SAR data sets. The performance of the algorithm to noise and spatial resolution were explored. Surface renderings were readily recognizable over a range of spatial resolution, and maintained their fidelity even under relatively low Signal-to-Noise Ratio (SNR) conditions.

  9. 3D surface analysis and classification in neuroimaging segmentation.

    PubMed

    Zagar, Martin; Mlinarić, Hrvoje; Knezović, Josip

    2011-06-01

    This work emphasizes new algorithms for 3D edge and corner detection used in surface extraction and new concept of image segmentation in neuroimaging based on multidimensional shape analysis and classification. We propose using of NifTI standard for describing input data which enables interoperability and enhancement of existing computing tools used widely in neuroimaging research. In methods section we present our newly developed algorithm for 3D edge and corner detection, together with the algorithm for estimating local 3D shape. Surface of estimated shape is analyzed and segmented according to kernel shapes. PMID:21755723

  10. Spectrum simulation of rough and nanostructured targets from their 2D and 3D image by Monte Carlo methods

    NASA Astrophysics Data System (ADS)

    Schiettekatte, François; Chicoine, Martin

    2016-03-01

    Corteo is a program that implements Monte Carlo (MC) method to simulate ion beam analysis (IBA) spectra of several techniques by following the ions trajectory until a sufficiently large fraction of them reach the detector to generate a spectrum. Hence, it fully accounts for effects such as multiple scattering (MS). Here, a version of Corteo is presented where the target can be a 2D or 3D image. This image can be derived from micrographs where the different compounds are identified, therefore bringing extra information into the solution of an IBA spectrum, and potentially significantly constraining the solution. The image intrinsically includes many details such as the actual surface or interfacial roughness, or actual nanostructures shape and distribution. This can for example lead to the unambiguous identification of structures stoichiometry in a layer, or at least to better constraints on their composition. Because MC computes in details the trajectory of the ions, it simulates accurately many of its aspects such as ions coming back into the target after leaving it (re-entry), as well as going through a variety of nanostructures shapes and orientations. We show how, for example, as the ions angle of incidence becomes shallower than the inclination distribution of a rough surface, this process tends to make the effective roughness smaller in a comparable 1D simulation (i.e. narrower thickness distribution in a comparable slab simulation). Also, in ordered nanostructures, target re-entry can lead to replications of a peak in a spectrum. In addition, bitmap description of the target can be used to simulate depth profiles such as those resulting from ion implantation, diffusion, and intermixing. Other improvements to Corteo include the possibility to interpolate the cross-section in angle-energy tables, and the generation of energy-depth maps.

  11. Surface classification and detection of latent fingerprints based on 3D surface texture parameters

    NASA Astrophysics Data System (ADS)

    Gruhn, Stefan; Fischer, Robert; Vielhauer, Claus

    2012-06-01

    In the field of latent fingerprint detection in crime scene forensics the classification of surfaces has importance. A new method for the scientific analysis of image based information for forensic science was investigated in the last years. Our image acquisition based on a sensor using Chromatic White Light (CWL) with a lateral resolution up to 2 μm. The used FRT-MicroProf 200 CWL 600 measurement device is able to capture high-resolution intensity and topography images in an optical and contact-less way. In prior work, we have suggested to use 2D surface texture parameters to classify various materials, which was a novel approach in the field of criminalistic forensic using knowledge from surface appearance and a chromatic white light sensor. A meaningful and useful classification of different crime scene specific surfaces is not existent. In this work, we want to extend such considerations by the usage of fourteen 3D surface parameters, called 'Birmingham 14'. In our experiment we define these surface texture parameters and use them to classify ten different materials in this test set-up and create specific material classes. Further it is shown in first experiments, that some surface texture parameters are sensitive to separate fingerprints from carrier surfaces. So far, the use of surface roughness is mainly known within the framework of material quality control. The analysis and classification of the captured 3D-topography images from crime scenes is important for the adaptive preprocessing depending on the surface texture. The adaptive preprocessing in dependency of surface classification is necessary for precise detection because of the wide variety of surface textures. We perform a preliminary study in usage of these 3D surface texture parameters as feature for the fingerprint detection. In combination with a reference sample we show that surface texture parameters can be an indication for a fingerprint and can be a feature in latent fingerprint detection.

  12. 3D face recognition based on matching of facial surfaces

    NASA Astrophysics Data System (ADS)

    Echeagaray-Patrón, Beatriz A.; Kober, Vitaly

    2015-09-01

    Face recognition is an important task in pattern recognition and computer vision. In this work a method for 3D face recognition in the presence of facial expression and poses variations is proposed. The method uses 3D shape data without color or texture information. A new matching algorithm based on conformal mapping of original facial surfaces onto a Riemannian manifold followed by comparison of conformal and isometric invariants computed in the manifold is suggested. Experimental results are presented using common 3D face databases that contain significant amount of expression and pose variations.

  13. Optical methods for cylindrical rough surface testing

    NASA Astrophysics Data System (ADS)

    Perez Quintian, F.; Rebollo, Maria A.; Gaggioli, Nestor G.; Raffo, C. A.

    1999-07-01

    This work studies theoretically the scattering of light from cylindrical rough surfaces. It is shown, for the conical diffraction configuration, that the mean intensity on an observation plane perpendicular to the cylinder longitudinal axis, is related to the statistical parameters that characterize the surface: the roughness (sigma) and the correlation length T.

  14. Transaction rules for updating surfaces in 3D GIS

    NASA Astrophysics Data System (ADS)

    Gröger, Gerhard; Plümer, Lutz

    2012-04-01

    Three-dimensional surface models representing the terrain and the outer hull of objects such as buildings and bridges support important 3D GIS applications, for example telecommunication planning and noise emission simulation. Updates of surface models often introduce errors which violate basic assumptions of users and their applications. The notion of geometric-topological consistency covers many of these assumptions. It guarantees that objects do not penetrate mutually or that objects completely cover other objects. Assuring that updates do not violate geometric-topological consistency constitutes a major challenge for 3D GIS which has not been satisfactorily met so far. This article presents a solution which is based on efficient transaction rules for updating 3D surface models. We show that these rules are safe (consistency is preserved by any rule application) and complete (any consistent surface model can be generated by successive rule applications). For both properties rigorous mathematic proofs are given.

  15. 3D Human cartilage surface characterization by optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Brill, Nicolai; Riedel, Jörn; Schmitt, Robert; Tingart, Markus; Truhn, Daniel; Pufe, Thomas; Jahr, Holger; Nebelung, Sven

    2015-10-01

    Early diagnosis and treatment of cartilage degeneration is of high clinical interest. Loss of surface integrity is considered one of the earliest and most reliable signs of degeneration, but cannot currently be evaluated objectively. Optical Coherence Tomography (OCT) is an arthroscopically available light-based non-destructive real-time imaging technology that allows imaging at micrometre resolutions to millimetre depths. As OCT-based surface evaluation standards remain to be defined, the present study investigated the diagnostic potential of 3D surface profile parameters in the comprehensive evaluation of cartilage degeneration. To this end, 45 cartilage samples of different degenerative grades were obtained from total knee replacements (2 males, 10 females; mean age 63.8 years), cut to standard size and imaged using a spectral-domain OCT device (Thorlabs, Germany). 3D OCT datasets of 8  ×  8, 4  ×  4 and 1  ×  1 mm (width  ×  length) were obtained and pre-processed (image adjustments, morphological filtering). Subsequent automated surface identification algorithms were used to obtain the 3D primary profiles, which were then filtered and processed using established algorithms employing ISO standards. The 3D surface profile thus obtained was used to calculate a set of 21 3D surface profile parameters, i.e. height (e.g. Sa), functional (e.g. Sk), hybrid (e.g. Sdq) and segmentation-related parameters (e.g. Spd). Samples underwent reference histological assessment according to the Degenerative Joint Disease classification. Statistical analyses included calculation of Spearman’s rho and assessment of inter-group differences using the Kruskal Wallis test. Overall, the majority of 3D surface profile parameters revealed significant degeneration-dependent differences and correlations with the exception of severe end-stage degeneration and were of distinct diagnostic value in the assessment of surface integrity. None of the 3D

  16. 3D Human cartilage surface characterization by optical coherence tomography.

    PubMed

    Brill, Nicolai; Riedel, Jörn; Schmitt, Robert; Tingart, Markus; Truhn, Daniel; Pufe, Thomas; Jahr, Holger; Nebelung, Sven

    2015-10-01

    Early diagnosis and treatment of cartilage degeneration is of high clinical interest. Loss of surface integrity is considered one of the earliest and most reliable signs of degeneration, but cannot currently be evaluated objectively. Optical Coherence Tomography (OCT) is an arthroscopically available light-based non-destructive real-time imaging technology that allows imaging at micrometre resolutions to millimetre depths. As OCT-based surface evaluation standards remain to be defined, the present study investigated the diagnostic potential of 3D surface profile parameters in the comprehensive evaluation of cartilage degeneration. To this end, 45 cartilage samples of different degenerative grades were obtained from total knee replacements (2 males, 10 females; mean age 63.8 years), cut to standard size and imaged using a spectral-domain OCT device (Thorlabs, Germany). 3D OCT datasets of 8  ×  8, 4  ×  4 and 1  ×  1 mm (width  ×  length) were obtained and pre-processed (image adjustments, morphological filtering). Subsequent automated surface identification algorithms were used to obtain the 3D primary profiles, which were then filtered and processed using established algorithms employing ISO standards. The 3D surface profile thus obtained was used to calculate a set of 21 3D surface profile parameters, i.e. height (e.g. Sa), functional (e.g. Sk), hybrid (e.g. Sdq) and segmentation-related parameters (e.g. Spd). Samples underwent reference histological assessment according to the Degenerative Joint Disease classification. Statistical analyses included calculation of Spearman's rho and assessment of inter-group differences using the Kruskal Wallis test. Overall, the majority of 3D surface profile parameters revealed significant degeneration-dependent differences and correlations with the exception of severe end-stage degeneration and were of distinct diagnostic value in the assessment of surface integrity. None of the 3D surface

  17. 3D surface digitizing and modeling development at ITRI

    NASA Astrophysics Data System (ADS)

    Hsueh, Wen-Jean

    2000-06-01

    This paper gives an overview of the research and development activities in 3D surface digitizing and modeling conducted at the Industrial Technology Research Institute (ITRI) of Taiwan in the past decade. As a major technology and consulting service provider of the area, ITRI has developed 3D laser scanning digitizers ranging from low-cost compacts, industrial CAD/CAM digitizing, to large human body scanner, with in-house 3D surface modeling software to provide total solution in reverse engineering that requires processing capabilities of large number of 3D data. Based on both hardware and software technologies in scanning, merging, registration, surface fitting, reconstruction, and compression, ITRI is now exploring innovative methodologies that provide higher performances, including hardware-based correlation algorithms with advanced camera designs, animation surface model reconstruction, and optical tracking for motion capture. It is expected that the need for easy and fast high-quality 3D information in the near future will grow exponentially, at the same amazing rate as the internet and the human desire for realistic and natural images.

  18. Evaluation of 3D surface scanners for skin documentation in forensic medicine: comparison of benchmark surfaces

    PubMed Central

    Schweitzer, Wolf; Häusler, Martin; Bär, Walter; Schaepman, Michael

    2007-01-01

    the limits of the manufacturer's specifications. When designing practically constrained specific tests, benchmark objects should be designed to contain features relevant for the application domain. As costs for 3D scanner hardware, software and data analysis can be hundred times as high compared to high-resolution digital photography equipment, independent user driven evaluation of such systems is paramount. Index terms Forensic pathology, Rough surfaces, Surface Scanning, Technology Assessment PMID:17266746

  19. Effect of Surface Roughness on Hydrodynamic Bearings

    NASA Technical Reports Server (NTRS)

    Majumdar, B. C.; Hamrock, B. J.

    1981-01-01

    A theoretical analysis on the performance of hydrodynamic oil bearings is made considering surface roughness effect. The hydrodynamic as well as asperity contact load is found. The contact pressure was calculated with the assumption that the surface height distribution was Gaussian. The average Reynolds equation of partially lubricated surface was used to calculate hydrodynamic load. An analytical expression for average gap was found and was introduced to modify the average Reynolds equation. The resulting boundary value problem was then solved numerically by finite difference methods using the method of successive over relaxation. The pressure distribution and hydrodynamic load capacity of plane slider and journal bearings were calculated for various design data. The effects of attitude and roughness of surface on the bearing performance were shown. The results are compared with similar available solution of rough surface bearings. It is shown that: (1) the contribution of contact load is not significant; and (2) the hydrodynamic and contact load increase with surface roughness.

  20. Surface roughness effects on bidirectional reflectance

    NASA Technical Reports Server (NTRS)

    Smith, T. F.; Hering, R. G.

    1972-01-01

    An experimental study of surface roughness effects on bidirectional reflectance of metallic surfaces is presented. A facility capable of irradiating a sample from normal to grazing incidence and recording plane of incidence bidirectional reflectance measurements was developed. Samples consisting of glass, aluminum alloy, and stainless steel materials were selected for examination. Samples were roughened using standard grinding techniques and coated with a radiatively opaque layer of pure aluminum. Mechanical surface roughness parameters, rms heights and rms slopes, evaluated from digitized surface profile measurements are less than 1.0 micrometers and 0.28, respectively. Rough surface specular, bidirectional, and directional reflectance measurements for selected values of polar angle of incidence and wavelength of incident energy within the spectral range of 1 to 14 micrometers are reported. The Beckmann bidirectional reflectance model is compared with reflectance measurements to establish its usefulness in describing the magnitude and spatial distribution of energy reflected from rough surfaces.

  1. Modeling surface roughness scattering in metallic nanowires

    SciTech Connect

    Moors, Kristof; Sorée, Bart; Magnus, Wim

    2015-09-28

    Ando's model provides a rigorous quantum-mechanical framework for electron-surface roughness scattering, based on the detailed roughness structure. We apply this method to metallic nanowires and improve the model introducing surface roughness distribution functions on a finite domain with analytical expressions for the average surface roughness matrix elements. This approach is valid for any roughness size and extends beyond the commonly used Prange-Nee approximation. The resistivity scaling is obtained from the self-consistent relaxation time solution of the Boltzmann transport equation and is compared to Prange-Nee's approach and other known methods. The results show that a substantial drop in resistivity can be obtained for certain diameters by achieving a large momentum gap between Fermi level states with positive and negative momentum in the transport direction.

  2. Roughness Perception of Haptically Displayed Fractal Surfaces

    NASA Technical Reports Server (NTRS)

    Costa, Michael A.; Cutkosky, Mark R.; Lau, Sonie (Technical Monitor)

    2000-01-01

    Surface profiles were generated by a fractal algorithm and haptically rendered on a force feedback joystick, Subjects were asked to use the joystick to explore pairs of surfaces and report to the experimenter which of the surfaces they felt was rougher. Surfaces were characterized by their root mean square (RMS) amplitude and their fractal dimension. The most important factor affecting the perceived roughness of the fractal surfaces was the RMS amplitude of the surface. When comparing surfaces of fractal dimension 1.2-1.35 it was found that the fractal dimension was negatively correlated with perceived roughness.

  3. Rough surface reconstruction for ultrasonic NDE simulation

    SciTech Connect

    Choi, Wonjae; Shi, Fan; Lowe, Michael J. S.; Skelton, Elizabeth A.; Craster, Richard V.

    2014-02-18

    The reflection of ultrasound from rough surfaces is an important topic for the NDE of safety-critical components, such as pressure-containing components in power stations. The specular reflection from a rough surface of a defect is normally lower than it would be from a flat surface, so it is typical to apply a safety factor in order that justification cases for inspection planning are conservative. The study of the statistics of the rough surfaces that might be expected in candidate defects according to materials and loading, and the reflections from them, can be useful to develop arguments for realistic safety factors. This paper presents a study of real rough crack surfaces that are representative of the potential defects in pressure-containing power plant. Two-dimensional (area) values of the height of the roughness have been measured and their statistics analysed. Then a means to reconstruct model cases with similar statistics, so as to enable the creation of multiple realistic realizations of the surfaces, has been investigated, using random field theory. Rough surfaces are reconstructed, based on a real surface, and results for these two-dimensional descriptions of the original surface have been compared with those from the conventional model based on a one-dimensional correlation coefficient function. In addition, ultrasonic reflections from them are simulated using a finite element method.

  4. A 3D surface imaging system for assessing human obesity

    NASA Astrophysics Data System (ADS)

    Xu, B.; Yu, W.; Yao, M.; Yao, X.; Li, Q.; Pepper, M. R.; Freeland-Graves, J. H.

    2009-08-01

    The increasing prevalence of obesity suggests a need to develop a convenient, reliable and economical tool for assessment of this condition. Three-dimensional (3D) body surface imaging has emerged as an exciting technology for estimation of body composition. This paper presents a new 3D body imaging system, which was designed for enhanced portability, affordability, and functionality. In this system, stereo vision technology was used to satisfy the requirements for a simple hardware setup and fast image acquisitions. The portability of the system was created via a two-stand configuration, and the accuracy of body volume measurements was improved by customizing stereo matching and surface reconstruction algorithms that target specific problems in 3D body imaging. Body measurement functions dedicated to body composition assessment also were developed. The overall performance of the system was evaluated in human subjects by comparison to other conventional anthropometric methods, as well as air displacement plethysmography, for body fat assessment.

  5. Overview of 3D surface digitization technologies in Europe

    NASA Astrophysics Data System (ADS)

    D'Apuzzo, Nicola

    2006-02-01

    This paper presents an overview of the different 3D surface digitization technologies commercially available in the European market. The solutions for 3D surface measurement offered by major European companies can be divided into different groups depending on various characteristics, such as technology (e.g. laser scanning, white light projection), system construction (e.g. fix, on CMM/robot/arm) or measurement type (e.g. surface scanning, profile scanning). Crossing between the categories is possible, however, the majority of commercial products can be divided into the following groups: (a) laser profilers mounted on CMM, (b) portable coded light projection systems, (c) desktop solutions with laser profiler or coded light projectin system and multi-axes platform, (d) laser point measurement systems where both sensor and object move, (e) hand operated laser profilers, hand held laser profiler or point measurement systems, (f) dedicated systems. This paper presents the different 3D surface digitization technologies and describes them with their advantages and disadvantages. Various examples of their use are shown for different application fields. A special interest is given to applications regarding the 3D surface measurement of the human body.

  6. 3DSEM++: Adaptive and intelligent 3D SEM surface reconstruction.

    PubMed

    Tafti, Ahmad P; Holz, Jessica D; Baghaie, Ahmadreza; Owen, Heather A; He, Max M; Yu, Zeyun

    2016-08-01

    Structural analysis of microscopic objects is a longstanding topic in several scientific disciplines, such as biological, mechanical, and materials sciences. The scanning electron microscope (SEM), as a promising imaging equipment has been around for decades to determine the surface properties (e.g., compositions or geometries) of specimens by achieving increased magnification, contrast, and resolution greater than one nanometer. Whereas SEM micrographs still remain two-dimensional (2D), many research and educational questions truly require knowledge and facts about their three-dimensional (3D) structures. 3D surface reconstruction from SEM images leads to remarkable understanding of microscopic surfaces, allowing informative and qualitative visualization of the samples being investigated. In this contribution, we integrate several computational technologies including machine learning, contrario methodology, and epipolar geometry to design and develop a novel and efficient method called 3DSEM++ for multi-view 3D SEM surface reconstruction in an adaptive and intelligent fashion. The experiments which have been performed on real and synthetic data assert the approach is able to reach a significant precision to both SEM extrinsic calibration and its 3D surface modeling. PMID:27200484

  7. Layering of ionic liquids on rough surfaces

    NASA Astrophysics Data System (ADS)

    Sheehan, Alexis; Jurado, L. Andres; Ramakrishna, Shivaprakash N.; Arcifa, Andrea; Rossi, Antonella; Spencer, Nicholas D.; Espinosa-Marzal, Rosa M.

    2016-02-01

    Understanding the behavior of ionic liquids (ILs) either confined between rough surfaces or in rough nanoscale pores is of great relevance to extend studies performed on ideally flat surfaces to real applications. In this work we have performed an extensive investigation of the structural forces between two surfaces with well-defined roughness (<9 nm RMS) in 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide by atomic force microscopy. Statistical studies of the measured layer thicknesses, layering force, and layering frequency reveal the ordered structure of the rough IL-solid interface. Our work shows that the equilibrium structure of the interfacial IL strongly depends on the topography of the contact.Understanding the behavior of ionic liquids (ILs) either confined between rough surfaces or in rough nanoscale pores is of great relevance to extend studies performed on ideally flat surfaces to real applications. In this work we have performed an extensive investigation of the structural forces between two surfaces with well-defined roughness (<9 nm RMS) in 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide by atomic force microscopy. Statistical studies of the measured layer thicknesses, layering force, and layering frequency reveal the ordered structure of the rough IL-solid interface. Our work shows that the equilibrium structure of the interfacial IL strongly depends on the topography of the contact. Electronic supplementary information (ESI) available: Optimized geometries and sizes for [HMIM] Ntf2, SEM images of the smooth and rough colloids, frequency of occurrence of layering in the resolved force-distance curves for all investigated systems with [HMIM] Ntf2, layer size and layering force measured with a sharp tip on mica for the same IL, and results of the kinetics experiments. See DOI: 10.1039/c5nr07805a

  8. 3D precision surface measurement by dynamic structured light

    NASA Astrophysics Data System (ADS)

    Franke, Ernest A.; Magee, Michael J.; Mitchell, Joseph N.; Rigney, Michael P.

    2004-02-01

    This paper describes a 3-D imaging technique developed as an internal research project at Southwest Research Institute. The technique is based on an extension of structured light methods in which a projected pattern of parallel lines is rotated over the surface to be measured. A sequence of images is captured and the surface elevation at any location can then be determined from measurements of the temporal pattern, at any point, without considering any other points on the surface. The paper describes techniques for system calibration and surface measurement based on the method of projected quadric shells. Algorithms were developed for image and signal analysis and computer programs were written to calibrate the system and to calculate 3-D coordinates of points on a measured surface. A prototype of the Dynamic Structured Light (DSL) 3-D imaging system was assembled and typical parts were measured. The design procedure was verified and used to implement several different configurations with different measurement volumes and measurement accuracy. A small-parts measurement accuracy of 32 micrometers (.0012") RMS was verified by measuring the surface of a precision-machined plane. Large aircraft control surfaces were measured with a prototype setup that provided .02" depth resolution over a 4" by 8" field of view. Measurement times are typically less than three minutes for 300,000 points. A patent application has been filed.

  9. MR image denoising method for brain surface 3D modeling

    NASA Astrophysics Data System (ADS)

    Zhao, De-xin; Liu, Peng-jie; Zhang, De-gan

    2014-11-01

    Three-dimensional (3D) modeling of medical images is a critical part of surgical simulation. In this paper, we focus on the magnetic resonance (MR) images denoising for brain modeling reconstruction, and exploit a practical solution. We attempt to remove the noise existing in the MR imaging signal and preserve the image characteristics. A wavelet-based adaptive curve shrinkage function is presented in spherical coordinates system. The comparative experiments show that the denoising method can preserve better image details and enhance the coefficients of contours. Using these denoised images, the brain 3D visualization is given through surface triangle mesh model, which demonstrates the effectiveness of the proposed method.

  10. Heat Transfer and Friction-Factor Methods Turbulent Flow Inside Pipes 3d Rough

    1994-01-21

    Three-dimensional roughened internally enhanced tubes have been shown to be one of the most energy efficient for turbulent, forced convection applications. However, there is only one prediction method presented in the open literature and that is restricted to three-dimensional sand-grain roughness. Other roughness types are being proposed: hemispherical sectors, truncated cones, and full and truncated pyramids. There are no validated heat-transfer and friction-factor prediction methods for these different roughness shapes that can be used inmore » the transition and fully rough region. This program calculates the Nusselt number and friction factor values, for a broad range of three-dimensional roughness types such as hemispherical sectors, truncated cones, and full and truncated pyramids. Users of this program are heat-exchangers designers, enhanced tubing suppliers, and research organizations or academia who are developing or validating prediction methods.« less

  11. Simplified Approach to Predicting Rough Surface Transition

    NASA Technical Reports Server (NTRS)

    Boyle, R. J.; Stripf, M.

    2009-01-01

    Turbine vane heat transfer predictions are given for smooth and rough vanes where the experimental data show transition moving forward on the vane as the surface roughness physical height increases. Consistent with smooth vane heat transfer, the transition moves forward for a fixed roughness height as the Reynolds number increases. Comparisons are presented with published experimental data. Some of the data are for a regular roughness geometry with a range of roughness heights, Reynolds numbers, and inlet turbulence intensities. The approach taken in this analysis is to treat the roughness in a statistical sense, consistent with what would be obtained from blades measured after exposure to actual engine environments. An approach is given to determine the equivalent sand grain roughness from the statistics of the regular geometry. This approach is guided by the experimental data. A roughness transition criterion is developed, and comparisons are made with experimental data over the entire range of experimental test conditions. Additional comparisons are made with experimental heat transfer data, where the roughness geometries are both regular and statistical. Using the developed analysis, heat transfer calculations are presented for the second stage vane of a high pressure turbine at hypothetical engine conditions.

  12. Simplified Approach to Predicting Rough Surface Transition

    NASA Technical Reports Server (NTRS)

    Boyle, Robert J.; Stripf, Matthias

    2009-01-01

    Turbine vane heat transfer predictions are given for smooth and rough vanes where the experimental data show transition moving forward on the vane as the surface roughness physical height increases. Consiste nt with smooth vane heat transfer, the transition moves forward for a fixed roughness height as the Reynolds number increases. Comparison s are presented with published experimental data. Some of the data ar e for a regular roughness geometry with a range of roughness heights, Reynolds numbers, and inlet turbulence intensities. The approach ta ken in this analysis is to treat the roughness in a statistical sense , consistent with what would be obtained from blades measured after e xposure to actual engine environments. An approach is given to determ ine the equivalent sand grain roughness from the statistics of the re gular geometry. This approach is guided by the experimental data. A roughness transition criterion is developed, and comparisons are made with experimental data over the entire range of experimental test co nditions. Additional comparisons are made with experimental heat tran sfer data, where the roughness geometries are both regular as well a s statistical. Using the developed analysis, heat transfer calculatio ns are presented for the second stage vane of a high pressure turbine at hypothetical engine conditions.

  13. Synthesizing 3D Surfaces from Parameterized Strip Charts

    NASA Technical Reports Server (NTRS)

    Robinson, Peter I.; Gomez, Julian; Morehouse, Michael; Gawdiak, Yuri

    2004-01-01

    We believe 3D information visualization has the power to unlock new levels of productivity in the monitoring and control of complex processes. Our goal is to provide visual methods to allow for rapid human insight into systems consisting of thousands to millions of parameters. We explore this hypothesis in two complex domains: NASA program management and NASA International Space Station (ISS) spacecraft computer operations. We seek to extend a common form of visualization called the strip chart from 2D to 3D. A strip chart can display the time series progression of a parameter and allows for trends and events to be identified. Strip charts can be overlayed when multiple parameters need to visualized in order to correlate their events. When many parameters are involved, the direct overlaying of strip charts can become confusing and may not fully utilize the graphing area to convey the relationships between the parameters. We provide a solution to this problem by generating 3D surfaces from parameterized strip charts. The 3D surface utilizes significantly more screen area to illustrate the differences in the parameters and the overlayed strip charts, and it can rapidly be scanned by humans to gain insight. The selection of the third dimension must be a parallel or parameterized homogenous resource in the target domain, defined using a finite, ordered, enumerated type, and not a heterogeneous type. We demonstrate our concepts with examples from the NASA program management domain (assessing the state of many plans) and the computers of the ISS (assessing the state of many computers). We identify 2D strip charts in each domain and show how to construct the corresponding 3D surfaces. The user can navigate the surface, zooming in on regions of interest, setting a mark and drilling down to source documents from which the data points have been derived. We close by discussing design issues, related work, and implementation challenges.

  14. Photochemistry on rough metal surfaces

    SciTech Connect

    Goncher, G.M.; Parsons, C.A.; Harris, C.B.

    1984-09-13

    The general question of laser-induced photochemistry on metal surfaces is addressed. Specifically, the authors have studied resonant photodecomposition of a variety of aromatic molecules on roughened silver surfaces in ultrahigh vacuum. A continuous ion laser source at a number of different wavelengths in the region 350-410 nm was used to produce graphitic carbon on the surface which was monitored by Raman spectroscopy at the 1580-cm/sup -1/ band of surface carbon. Laser power-dependence studies of fragmentation rate for several molecules at 406.7nm indicate that the initial absorption step is a two-photon process. Energetic considerations imply that photochemistry for other molecules studied is also due to multiphoton absorption, except for benzaldehyde fragmentation at 350.7-nm excitation, where the photodecomposition rate is linear. Distance-dependence studies of photofragmentation rates by use of an inert spacer layer to separatte the molecule undergoing photochemistry from the surface indicate that energy transfer to the metal surface is important in determining the reaction rate. Decomposition mechanism has not been fully evaluated.

  15. Thermal smoothing of rough surfaces in vacuo

    NASA Technical Reports Server (NTRS)

    Wahl, G.

    1986-01-01

    The derivation of equations governing the smoothing of rough surfaces, based on Mullins' (1957, 1960, and 1963) theories of thermal grooving and of capillarity-governed solid surface morphology is presented. As an example, the smoothing of a one-dimensional sine-shaped surface is discussed.

  16. 3D shape and eccentricity measurements of fast rotating rough objects by two mutually tilted interference fringe systems

    NASA Astrophysics Data System (ADS)

    Czarske, J. W.; Kuschmierz, R.; Günther, P.

    2013-06-01

    Precise measurements of distance, eccentricity and 3D-shape of fast moving objects such as turning parts of lathes, gear shafts, magnetic bearings, camshafts, crankshafts and rotors of vacuum pumps are on the one hand important tasks. On the other hand they are big challenges, since contactless precise measurement techniques are required. Optical techniques are well suitable for distance measurements of non-moving surfaces. However, measurements of laterally fast moving surfaces are still challenging. For such tasks the laser Doppler distance sensor technique was invented by the TU Dresden some years ago. This technique has been realized by two mutually tilted interference fringe systems, where the distance is coded in the phase difference between the generated interference signals. However, due to the speckle effect different random envelopes and phase jumps of the interference signals occur. They disturb the phase difference estimation between the interference signals. In this paper, we will report on a scientific breakthrough on the measurement uncertainty budget which has been achieved recently. Via matching of the illumination and receiving optics the measurement uncertainty of the displacement and distance can be reduced by about one magnitude. For displacement measurements of a recurring rough surface a standard deviation of 110 nm were attained at lateral velocities of 5 m / s. Due to the additionally measured lateral velocity and the rotational speed, the two-dimensional shape of rotating objects is calculated. The three-dimensional shape can be conducted by employment of a line camera. Since the measurement uncertainty of the displacement, vibration, distance, eccentricity, and shape is nearly independent of the lateral surface velocity, this technique is predestined for fast-rotating objects. Especially it can be advantageously used for the quality control of workpieces inside of a lathe towards the reduction of process tolerances, installation times and

  17. 3D surface configuration modulates 2D symmetry detection.

    PubMed

    Chen, Chien-Chung; Sio, Lok-Teng

    2015-02-01

    We investigated whether three-dimensional (3D) information in a scene can affect symmetry detection. The stimuli were random dot patterns with 15% dot density. We measured the coherence threshold, or the proportion of dots that were the mirror reflection of the other dots in the other half of the image about a central vertical axis, at 75% accuracy with a 2AFC paradigm under various 3D configurations produced by the disparity between the left and right eye images. The results showed that symmetry detection was difficult when the corresponding dots across the symmetry axis were on different frontoparallel or inclined planes. However, this effect was not due to a difference in distance, as the observers could detect symmetry on a slanted surface, where the depth of the two sides of the symmetric axis was different. The threshold was reduced for a hinge configuration where the join of two slanted surfaces coincided with the axis of symmetry. Our result suggests that the detection of two-dimensional (2D) symmetry patterns is subject to the 3D configuration of the scene; and that coplanarity across the symmetry axis and consistency between the 2D pattern and 3D structure are important factors for symmetry detection. PMID:25536469

  18. Surface roughness effects on equilibrium temperature.

    NASA Technical Reports Server (NTRS)

    Houchens, A. F.; Hering, R. G.

    1972-01-01

    An analysis is presented for evaluation of equilibrium temperature distribution on radiatively adiabatic, adjoint planes which are uniformly irradiated by a collimated solar flux. The analysis employs a semigrey spectral model. Radiation properties for surface emitted radiation are obtained from the expressions of electromagnetic theory for smooth surfaces. Rough surface properties for solar radiation are given by the Beckmann bidirectional reflectance model. Numerical solutions to the governing equations yield equilibrium temperature distributions for a range of the influencing parameters. Surface roughness has little influence on equilibrium temperature for materials with high values for solar absorptance. However, for low or intermediate values of solar absorptance, roughness effects on the spatial distribution of reflected solar radiation can significantly alter equilibrium temperature particularly at surface elements where radiant interaction is small.

  19. Prediction of incidence and surface roughness effects on turbine performance

    NASA Technical Reports Server (NTRS)

    Boyle, R. J.

    1993-01-01

    The results of a Navier-Stokes analysis for predicting the change in turbine efficiency due to a change in either incidence or surface roughness is discussed. It was experimentally determined by Boynton, Tabibzadeh, and Hudson that polishing the SSME high pressure fuel turbine blades improved turbine efficiency by about 2 points over a wide range of operating conditions. These conditions encompassed the range of incidence seen by the turbine blading during flight. It is also necessary to be able to predict turbine performance at various operating points for future rocket turbopump applications. The code RVCQ3D, developed by Rod Chima, was used to determine the effects of changes in incidence angle on turbine blade row efficiency. The midspan Navier-Stokes results were used in conjunction with an inviscid flow analysis code to predict the efficiency of the two stage SSME over a wide range of operating conditions for smooth and rough turbine blades. The use of the Navier-Stokes analysis to predict changes in turbine efficiency due to variation in incidence angles was found to be superior to other incidence loss correlations available in the literature. The sensitivity of the Navier-Stokes results to grid parameters is discussed. The effects of the surface roughness were accounted for using the Cebeci-Chang rough wall turbulence model. This model was implemented in the code RVCQ3D. The implementation of this model for predicting the change in efficiency is also discussed.

  20. Gravel-bed surface roughness from airborne laser scanning

    NASA Astrophysics Data System (ADS)

    Huang, G.; Wang, C.

    2011-12-01

    The roughness of gravel-bed surface is of great importance for fluvial geomorpholoy. Numerous studies have demonstrated that the fractal theory and the log-log variogram are useful for describing the multi-scaling behavior(grain scale and form scale) of the gravel-bed surface. In this study, we obtained the 3D surface information of the gravel surface of a central bar in Nan-Shih River, Taiwan using an airborne laser scanning with a nominal point density of 100 points/m2. The data were divided into 6m × 6m grids. The roughness characteristics of the gravel bar were discussed using the anisotropy axes (also called the directions of maximum and minimum continuity, respectively) determined from the variogram map for each grid. And, the fractal dimension of the two directions were also calculated.

  1. Holographic measurement of wall stress distribution and 3D flow over a surface textured by microfibers

    NASA Astrophysics Data System (ADS)

    Bocanegra, Humberto; Gorumlu, Seder; Aksak, Burak; Castillo, Luciano; Sheng, Jian

    2015-11-01

    Understanding how fluid flow interacts with micro-textured surfaces is crucial for a broad range of key biological processes and engineering applications including particle dispersion, pathogenic infections, and drag manipulation by surface topology. Existing methods, such as μPIV, suffers from low spatial resolution and fail to track tracer particle motion very close to a rough surface and within roughness elements. In this paper, we present a technique that combines high speed digital holographic microscopy (DHM) with a correlation based de-noising algorithm to overcome the optical interference generated by surface roughness and to capture a large number of 3D particle trajectories. It allows us to obtain a 3D velocity field with an uncertainty of 0.01% and 2D wall shear stress distribution at the resolution of ~ 65 μPa. Applying the technique to a microfluidics with a surface textured by microfibers, we find that the flow is three-dimensional and complex. While the microfibers affect the velocity flow field locally, their presence is felt globally in terms of wall shear stresses. The study of effect of microfiber patterns and flow characteristics on skin frictions are ongoing and will be reported.

  2. Molecular cartography of the human skin surface in 3D

    PubMed Central

    Bouslimani, Amina; Porto, Carla; Rath, Christopher M.; Wang, Mingxun; Guo, Yurong; Gonzalez, Antonio; Berg-Lyon, Donna; Ackermann, Gail; Moeller Christensen, Gitte Julie; Nakatsuji, Teruaki; Zhang, Lingjuan; Borkowski, Andrew W.; Meehan, Michael J.; Dorrestein, Kathleen; Gallo, Richard L.; Bandeira, Nuno; Knight, Rob; Alexandrov, Theodore; Dorrestein, Pieter C.

    2015-01-01

    The human skin is an organ with a surface area of 1.5–2 m2 that provides our interface with the environment. The molecular composition of this organ is derived from host cells, microbiota, and external molecules. The chemical makeup of the skin surface is largely undefined. Here we advance the technologies needed to explore the topographical distribution of skin molecules, using 3D mapping of mass spectrometry data and microbial 16S rRNA amplicon sequences. Our 3D maps reveal that the molecular composition of skin has diverse distributions and that the composition is defined not only by skin cells and microbes but also by our daily routines, including the application of hygiene products. The technological development of these maps lays a foundation for studying the spatial relationships of human skin with hygiene, the microbiota, and environment, with potential for developing predictive models of skin phenotypes tailored to individual health. PMID:25825778

  3. Molecular cartography of the human skin surface in 3D.

    PubMed

    Bouslimani, Amina; Porto, Carla; Rath, Christopher M; Wang, Mingxun; Guo, Yurong; Gonzalez, Antonio; Berg-Lyon, Donna; Ackermann, Gail; Moeller Christensen, Gitte Julie; Nakatsuji, Teruaki; Zhang, Lingjuan; Borkowski, Andrew W; Meehan, Michael J; Dorrestein, Kathleen; Gallo, Richard L; Bandeira, Nuno; Knight, Rob; Alexandrov, Theodore; Dorrestein, Pieter C

    2015-04-28

    The human skin is an organ with a surface area of 1.5-2 m(2) that provides our interface with the environment. The molecular composition of this organ is derived from host cells, microbiota, and external molecules. The chemical makeup of the skin surface is largely undefined. Here we advance the technologies needed to explore the topographical distribution of skin molecules, using 3D mapping of mass spectrometry data and microbial 16S rRNA amplicon sequences. Our 3D maps reveal that the molecular composition of skin has diverse distributions and that the composition is defined not only by skin cells and microbes but also by our daily routines, including the application of hygiene products. The technological development of these maps lays a foundation for studying the spatial relationships of human skin with hygiene, the microbiota, and environment, with potential for developing predictive models of skin phenotypes tailored to individual health. PMID:25825778

  4. Key techniques for vision measurement of 3D object surface

    NASA Astrophysics Data System (ADS)

    Yang, Huachao; Zhang, Shubi; Guo, Guangli; Liu, Chao; Yu, Ruipeng

    2006-11-01

    Digital close-range photogrammetry system and machine vision are widely used in production control, quality inspection. The main aim is to provide accurate 3D objects or reconstruction of an object surface and give an expression to an object shape. First, the key techniques of camera calibration and target image positioning for 3D object surface vision measurement were briefly reviewed and analyzed in this paper. Then, an innovative and effect method for precise space coordinates measurements was proposed. Test research proved that the thought and methods we proposed about image segmentation, detection and positioning of circular marks were effective and valid. A propriety weight value for adding parameters, control points and orientation elements in bundle adjustment with self-calibration are advantageous to gaining high accuracy of space coordinates. The RMS error of check points is less than +/-1 mm, which can meet the requirement in industrial measurement with high accuracy.

  5. Optimal Image Stitching for Concrete Bridge Bottom Surfaces Aided by 3d Structure Lines

    NASA Astrophysics Data System (ADS)

    Liu, Yahui; Yao, Jian; Liu, Kang; Lu, Xiaohu; Xia, Menghan

    2016-06-01

    Crack detection for bridge bottom surfaces via remote sensing techniques is undergoing a revolution in the last few years. For such applications, a large amount of images, acquired with high-resolution industrial cameras close to the bottom surfaces with some mobile platform, are required to be stitched into a wide-view single composite image. The conventional idea of stitching a panorama with the affine model or the homographic model always suffers a series of serious problems due to poor texture and out-of-focus blurring introduced by depth of field. In this paper, we present a novel method to seamlessly stitch these images aided by 3D structure lines of bridge bottom surfaces, which are extracted from 3D camera data. First, we propose to initially align each image in geometry based on its rough position and orientation acquired with both a laser range finder (LRF) and a high-precision incremental encoder, and these images are divided into several groups with the rough position and orientation data. Secondly, the 3D structure lines of bridge bottom surfaces are extracted from the 3D cloud points acquired with 3D cameras, which impose additional strong constraints on geometrical alignment of structure lines in adjacent images to perform a position and orientation optimization in each group to increase the local consistency. Thirdly, a homographic refinement between groups is applied to increase the global consistency. Finally, we apply a multi-band blending algorithm to generate a large-view single composite image as seamlessly as possible, which greatly eliminates both the luminance differences and the color deviations between images and further conceals image parallax. Experimental results on a set of representative images acquired from real bridge bottom surfaces illustrate the superiority of our proposed approaches.

  6. Design Application Translates 2-D Graphics to 3-D Surfaces

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Fabric Images Inc., specializing in the printing and manufacturing of fabric tension architecture for the retail, museum, and exhibit/tradeshow communities, designed software to translate 2-D graphics for 3-D surfaces prior to print production. Fabric Images' fabric-flattening design process models a 3-D surface based on computer-aided design (CAD) specifications. The surface geometry of the model is used to form a 2-D template, similar to a flattening process developed by NASA's Glenn Research Center. This template or pattern is then applied in the development of a 2-D graphic layout. Benefits of this process include 11.5 percent time savings per project, less material wasted, and the ability to improve upon graphic techniques and offer new design services. Partners include Exhibitgroup/Giltspur (end-user client: TAC Air, a division of Truman Arnold Companies Inc.), Jack Morton Worldwide (end-user client: Nickelodeon), as well as 3D Exhibits Inc., and MG Design Associates Corp.

  7. Correlation of Windspeed and Antarctic Surface Roughness

    NASA Astrophysics Data System (ADS)

    Stockham, Mark; Anita Collaboration

    2015-04-01

    When electromagnetic waves interact with a media interface the transmitted and reflected portions of the incoming wave depend on the incident angle of the wave and wavelength (as well as the material properties of the media). The roughness of the surface of Antarctica affects the radio frequency signals received by airborne experiments, such as the balloon-borne experiment ANITA (ANtarctic Impulsive Transient Antenna) which observes the reflected radio waves from cosmic ray-induced extensive air showers (EAS). Roughness of a given scale can cause decoherence of the reflected signal and is an important effect to understand when estimating the amplitude of the incoming wave based on the reflected wave. It is challenging to get a survey of surface roughness over many of the areas that these experiments are likely to pass over. Correlating historical wind speed records with statistical roughness as observed by the backscatter of satellite [Rémy F, Parouty S. Remote Sensing. 2009] and airborne experiments operating at different frequencies can possibly be used to predict time-dependent surface roughness with surface wind speed as the input. These correlations will be presented for a variety of areas on the Antarctic ice shelf. NASA Grant NNX11AC47G.

  8. Direct Orthogonal Distance to Quadratic Surfaces in 3D.

    PubMed

    Lott, Gus K

    2014-09-01

    Discovering the orthogonal distance to a quadratic surface is a classic geometric task in vision, modeling, and robotics. I describe a simple, efficient, and stable direct solution for the orthogonal distance (foot-point) to an arbitrary quadratic surface from a general finite 3D point. The problem is expressed as the intersection of three quadratic surfaces, two of which are derived from the requirement of orthogonality of two non-coincident planes with the tangent plane to the quadric. A sixth order single-variable polynomial is directly generated in one coordinate of the surface point. The method detects intersection points at infinity and operates smoothly across all real quadratic surface classes. The method also geometrically detects continuums of orthogonal points (i.e., from the exact center of a sphere). I discuss algorithm performance, compare it to a state-of-the-art estimator, demonstrate the algorithm on synthetic data, and describe extension to arbitrary dimension. PMID:26352239

  9. Application of Plenoptic PIV for 3D Velocity Measurements Over Roughness Elements in a Refractive Index Matched Facility

    NASA Astrophysics Data System (ADS)

    Thurow, Brian; Johnson, Kyle; Kim, Taehoon; Blois, Gianluca; Best, Jim; Christensen, Ken

    2014-11-01

    The application of Plenoptic PIV in a Refractive Index Matched (RIM) facility housed at Illinois is presented. Plenoptic PIV is an emerging 3D diagnostic that exploits the light-field imaging capabilities of a plenoptic camera. Plenoptic cameras utilize a microlens array to measure the position and angle of light rays captured by the camera. 3D/3C velocity fields are determined through application of the MART algorithm for volume reconstruction and a conventional 3D cross-correlation PIV algorithm. The RIM facility is a recirculating tunnel with a 62.5% aqueous solution of sodium iodide used as the working fluid. Its resulting index of 1.49 is equal to that of acrylic. Plenoptic PIV was used to measure the 3D velocity field of a turbulent boundary layer flow over a smooth wall, a single wall-mounted hemisphere and a full array of hemispheres (i.e. a rough wall) with a k/ δ ~ 4.6. Preliminary time averaged and instantaneous 3D velocity fields will be presented. This material is based upon work supported by the National Science Foundation under Grant No. 1235726.

  10. Venus surface roughness and Magellan stereo data

    NASA Technical Reports Server (NTRS)

    Maurice, Kelly E.; Leberl, Franz W.; Norikane, L.; Hensley, Scott

    1994-01-01

    Presented are results of some studies to develop tools useful for the analysis of Venus surface shape and its roughness. Actual work was focused on Maxwell Montes. The analyses employ data acquired by means of NASA's Magellan satellite. The work is primarily concerned with deriving measurements of the Venusian surface using Magellan stereo SAR. Roughness was considered by means of a theoretical analyses based on digital elevation models (DEM's), on single Magellan radar images combined with radiometer data, and on the use of multiple overlapping Magellan radar images from cycles 1, 2, and 3, again combined with collateral radiometer data.

  11. Surface roughness modulations by submesoscale currents

    NASA Astrophysics Data System (ADS)

    Rascle, Nicolas; Chapron, Bertrand; Nouguier, Frederic; Ponte, Aurelien; Mouche, Alexis; Molemaker, Jeroen

    2016-04-01

    At times, high resolution images of sea surface roughness can provide stunning details of submesoscale upper ocean dynamics. As interpreted, transformations of short scale wind waves by horizontal current gradients are responsible for those spectacular observations. Here we present two major advances towards the quantitative interpretation of those observations. First, we show that surface roughness variations mainly trace two particular characteristics of the current gradient tensor, the divergence and the strain in the wind direction. Local vorticity and shear in the wind direction should not affect short scale roughness distribution and would not be detectable. Second, we discuss the effect of the viewing direction using sets of quasi-simultaneous sun glitter images, taken from different satellites to provide different viewing configurations. We show that upwind and crosswind viewing observations can be markedly different. As further confirmed with idealized numerical simulations, this anisotropy well traces surface current strain area, while more isotropic contrasts likely trace areas dominated by surface divergence conditions. These findings suggest the potential to directly observe surface currents at submesoscale by using surface roughness observations at multiple azimuth viewing angles. They also pave the way towards a better understanding of the coupling between ocean, waves and atmosphere at high resolution.

  12. 3D Surface Reconstruction and Volume Calculation of Rills

    NASA Astrophysics Data System (ADS)

    Brings, Christine; Gronz, Oliver; Becker, Kerstin; Wirtz, Stefan; Seeger, Manuel; Ries, Johannes B.

    2015-04-01

    We use the low-cost, user-friendly photogrammetric Structure from Motion (SfM) technique, which is implemented in the Software VisualSfM, for 3D surface reconstruction and volume calculation of an 18 meter long rill in Luxembourg. The images were taken with a Canon HD video camera 1) before a natural rainfall event, 2) after a natural rainfall event and before a rill experiment and 3) after a rill experiment. Recording with a video camera results compared to a photo camera not only a huge time advantage, the method also guarantees more than adequately overlapping sharp images. For each model, approximately 8 minutes of video were taken. As SfM needs single images, we automatically selected the sharpest image from 15 frame intervals. The sharpness was estimated using a derivative-based metric. Then, VisualSfM detects feature points in each image, searches matching feature points in all image pairs, recovers the camera positions and finally by triangulation of camera positions and feature points the software reconstructs a point cloud of the rill surface. From the point cloud, 3D surface models (meshes) are created and via difference calculations of the pre and post models a visualization of the changes (erosion and accumulation areas) and quantification of erosion volumes are possible. The calculated volumes are presented in spatial units of the models and so real values must be converted via references. The outputs are three models at three different points in time. The results show that especially using images taken from suboptimal videos (bad lighting conditions, low contrast of the surface, too much in-motion unsharpness), the sharpness algorithm leads to much more matching features. Hence the point densities of the 3D models are increased and thereby clarify the calculations.

  13. Visualizing 3D velocity fields near contour surfaces

    SciTech Connect

    Max, N.; Crawfis, R.; Grant, C.

    1994-03-01

    Vector field rendering is difficult in 3D because the vector icons overlap and hide each other. We propose four different techniques for visualizing vector fields only near surfaces. The first uses motion blurred particles in a thickened region around the surface. The second uses a voxel grid to contain integral curves of the vector field. The third uses many antialiased lines through the surface, and the fourth uses hairs sprouting from the surface and then bending in the direction of the vector field. All the methods use the graphite pipeline, allowing real time rotation and interaction, and the first two methods can animate the texture to move in the flow determined by the velocity field.

  14. 3D Surface Topology Guides Stem Cell Adhesion and Differentiation

    PubMed Central

    Viswanathan, Priyalakshmi; Ondeck, Matthew G.; Chirasatitsin, Somyot; Nghamkham, Kamolchanok; Reilly, Gwendolen C.; Engler, Adam J.; Battaglia, Giuseppe

    2015-01-01

    Polymerized high internal phase emulsion (polyHIPE) foams are extremely versatile materials for investigating cell-substrate interactions in vitro. Foam morphologies can be controlled by polymerization conditions to result in either open or closed pore structures with different levels of connectivity, consequently enabling the comparison between 2D and 3D matrices using the same substrate with identical surface chemistry conditions. Additionally, here we achieve the control of pore surface topology (i.e. how different ligands are clustered together) using amphiphilic block copolymers as emulsion stabilisers. We demonstrate that adhesion of human mesenchymal progenitor (hES-MP) cells cultured on polyHIPE foams is dependent on foam surface topology and chemistry but is independent of porosity and interconnectivity. We also demonstrate that the interconnectivity, architecture and surface topology of the foams has an effect on the osteogenic differentiation potential of hES-MP cells. Together these data demonstrate that the adhesive heterogeneity of a 3D scaffold could regulate not only mesenchymal stem cell attachment but also cell behavior in the absence of soluble growth factors. PMID:25818420

  15. The geological interpretation of photometric surface roughness

    NASA Technical Reports Server (NTRS)

    Helfenstein, Paul

    1988-01-01

    A computer-generated km-scale relief map, whose topographic facets on scales of less than a few m are assumed to have smooth particulate surfaces, is the basis of the present investigation of the relationship between photometrically-derived values of Hapke's (1984) roughness parameter theta and topographic scale. The addition of m-km scale-range relief to the otherwise smooth surface alters integral photometric behavior in a way that is consistent with Hapke's equation; the roughness characterized by theta is an integral property over all scales up to the resolution limit of the photometric data used in its determination. With sufficient phase angle coverage, theta can distinguish terrains with very different integral roughnesses.

  16. Effective 3-D surface modeling for geographic information systems

    NASA Astrophysics Data System (ADS)

    Yüksek, K.; Alparslan, M.; Mendi, E.

    2013-11-01

    In this work, we propose a dynamic, flexible and interactive urban digital terrain platform (DTP) with spatial data and query processing capabilities of Geographic Information Systems (GIS), multimedia database functionality and graphical modeling infrastructure. A new data element, called Geo-Node, which stores image, spatial data and 3-D CAD objects is developed using an efficient data structure. The system effectively handles data transfer of Geo-Nodes between main memory and secondary storage with an optimized Directional Replacement Policy (DRP) based buffer management scheme. Polyhedron structures are used in Digital Surface Modeling (DSM) and smoothing process is performed by interpolation. The experimental results show that our framework achieves high performance and works effectively with urban scenes independent from the amount of spatial data and image size. The proposed platform may contribute to the development of various applications such as Web GIS systems based on 3-D graphics standards (e.g. X3-D and VRML) and services which integrate multi-dimensional spatial information and satellite/aerial imagery.

  17. Effective 3-D surface modeling for geographic information systems

    NASA Astrophysics Data System (ADS)

    Yüksek, K.; Alparslan, M.; Mendi, E.

    2016-01-01

    In this work, we propose a dynamic, flexible and interactive urban digital terrain platform with spatial data and query processing capabilities of geographic information systems, multimedia database functionality and graphical modeling infrastructure. A new data element, called Geo-Node, which stores image, spatial data and 3-D CAD objects is developed using an efficient data structure. The system effectively handles data transfer of Geo-Nodes between main memory and secondary storage with an optimized directional replacement policy (DRP) based buffer management scheme. Polyhedron structures are used in digital surface modeling and smoothing process is performed by interpolation. The experimental results show that our framework achieves high performance and works effectively with urban scenes independent from the amount of spatial data and image size. The proposed platform may contribute to the development of various applications such as Web GIS systems based on 3-D graphics standards (e.g., X3-D and VRML) and services which integrate multi-dimensional spatial information and satellite/aerial imagery.

  18. Surface roughness change on sandstone induced by temperature increase

    NASA Astrophysics Data System (ADS)

    Vlcko, J.; Kompanikova, Z.; Gomez-Heras, M.; Greif, V.; Durmekova, T.; Brcek, M.

    2012-04-01

    Optical surface profilometer allows capturing the information necessary to provide 3D surface measurements in a single image acquisition with a vertical micrometric resolution. The surface topography can be used for analyses, such as roughness evaluation. In this research, roughness changes of two types of sandstone samples were studied before and after heating to 60, 200, 400, 600 and 800 °C. Measurements obtained were converted into 3D 5 mm x 5 mm (25 mm2) topographic maps with a resolution of 2.5 µm. Surface roughness parameter Sq represents quantifies roughness from the maximum deviation along a mean surface and it is calculated as the root mean squared of five peaks and valleys of the specimen using Gaussian filter and 0.80 mm cut-off. The high spatial resolution obtained from visible-light optical surface profilometer is an ideal tool for observing rock surface alterations caused by decay factors. The authors present complete original process of surface roughness determination on rock samples adopting the portable profilometer using free accessible software packages. The different stability of the fabric of sandstones from Králiky and Oravská Jasenica after heating is due to their different mineral composition and different ratio of minerals that are more or less chemically stable at high temperatures, their resistance to thermal stress and other textural factors related to the distribution of grains and matrix. Percentage of minerals chemically stable at higher temperature, such as quartz, calcite, illite and muscovite, in fresh sandstone samples from Králiky is approximately 48%. Conversely, sandstones from Oravská Jasenica have significantly greater percentage of minerals stable at higher temperatures, such as quartz, albite, orthoclase, muscovite, illite and calcite than of other, less stable, minerals such as chlorite, biotite and kaolinite. Hence, percentage of minerals stable at higher temperatures was approximately 81 %. The results show how the

  19. Surface forces: Surface roughness in theory and experiment

    SciTech Connect

    Parsons, Drew F. Walsh, Rick B.; Craig, Vincent S. J.

    2014-04-28

    A method of incorporating surface roughness into theoretical calculations of surface forces is presented. The model contains two chief elements. First, surface roughness is represented as a probability distribution of surface heights around an average surface height. A roughness-averaged force is determined by taking an average of the classic flat-surface force, weighing all possible separation distances against the probability distributions of surface heights. Second the model adds a repulsive contact force due to the elastic contact of asperities. We derive a simple analytic expression for the contact force. The general impact of roughness is to amplify the long range behaviour of noncontact (DLVO) forces. The impact of the elastic contact force is to provide a repulsive wall which is felt at a separation between surfaces that scales with the root-mean-square (RMS) roughness of the surfaces. The model therefore provides a means of distinguishing between “true zero,” where the separation between the average centres of each surface is zero, and “apparent zero,” defined by the onset of the repulsive contact wall. A normal distribution may be assumed for the surface probability distribution, characterised by the RMS roughness measured by atomic force microscopy (AFM). Alternatively the probability distribution may be defined by the histogram of heights measured by AFM. Both methods of treating surface roughness are compared against the classic smooth surface calculation and experimental AFM measurement.

  20. 3D integration of sub-surface photonics with CMOS

    NASA Astrophysics Data System (ADS)

    Jalali, Bahram; Indukuri, Tejaswi; Koonath, Prakash

    2006-02-01

    The integration of photonics and electronics on a single silicon substrate requires technologies that can add optical functionalities without significantly sacrificing valuable wafer area. To this end, we have developed an innovative fabrication process, called SIMOX 3-D Sculpting, that enables monolithic optoelectronic integration in a manner that does not compromise the economics of CMOS manufacturing. In this technique, photonic devices are realized in subsurface silicon layers that are separated from the surface silicon layer by an intervening SiO II layer. The surface silicon layer may then be utilized for electronic circuitry. SIMOX 3-D sculpting involves (1) the implantation of oxygen ions into a patterned silicon substrate followed by (2) high temperature anneal to create buried waveguide-based photonic devices. This process has produced subterranean microresonators with unloaded quality factors of 8000 and extinction ratios >20dB. On the surface silicon layers, MOS transistor structures have been fabricated. The small cross-sectional area of the waveguides lends itself to the realization of nonlinear optical devices. We have previously demonstrated spectral broadening and continuum generation in silicon waveguides utilizing Kerr optical nonlinearity. This may be combined with microresonator filters for on-chip supercontiuum generation and spectral carving. The monolithic integration of CMOS circuits and optical modulators with such multi-wavelength sources represent an exciting avenue for silicon photonics.

  1. Hand surface area estimation formula using 3D anthropometry.

    PubMed

    Hsu, Yao-Wen; Yu, Chi-Yuang

    2010-11-01

    Hand surface area is an important reference in occupational hygiene and many other applications. This study derives a formula for the palm surface area (PSA) and hand surface area (HSA) based on three-dimensional (3D) scan data. Two-hundred and seventy subjects, 135 males and 135 females, were recruited for this study. The hand was measured using a high-resolution 3D hand scanner. Precision and accuracy of the scanner is within 0.67%. Both the PSA and HSA were computed using the triangular mesh summation method. A comparison between this study and previous textbook values (such as in the U.K. teaching text and Lund and Browder chart discussed in the article) was performed first to show that previous textbooks overestimated the PSA by 12.0% and HSA by 8.7% (for the male, PSA 8.5% and HSA 4.7%, and for the female, PSA 16.2% and HSA 13.4%). Six 1D measurements were then extracted semiautomatically for use as candidate estimators for the PSA and HSA estimation formula. Stepwise regressions on these six 1D measurements and variable dependency test were performed. Results show that a pair of measurements (hand length and hand breadth) were able to account for 96% of the HSA variance and up to 98% of the PSA variance. A test of the gender-specific formula indicated that gender is not a significant factor in either the PSA or HSA estimation. PMID:20865628

  2. Three-tier rough superhydrophobic surfaces.

    PubMed

    Cao, Yuanzhi; Yuan, Longyan; Hu, Bin; Zhou, Jun

    2015-08-01

    A three-tier rough superhydrophobic surface was fabricated by growing hydrophobic modified (fluorinated silane) zinc oxide (ZnO)/copper oxide (CuO) hetero-hierarchical structures on silicon (Si) micro-pillar arrays. Compared with the other three control samples with a less rough tier, the three-tier surface exhibits the best water repellency with the largest contact angle 161° and the lowest sliding angle 0.5°. It also shows a robust Cassie state which enables the water to flow with a speed over 2 m s(-1). In addition, it could prevent itself from being wetted by the droplet with low surface tension (mixed water and ethanol 1:1 in volume) which reveals a flow speed of 0.6 m s(-1) (dropped from the height of 2 cm). All these features prove that adding another rough tier on a two-tier rough surface could futher improve its water-repellent properties. PMID:26184512

  3. TLS - a tool for channel bed surface roughness determination?

    NASA Astrophysics Data System (ADS)

    Baewert, Henning; Morche, David

    2013-04-01

    Channel bed surface roughness has a significant influence on flow characteristics of a stream. Since decades roughness coefficient determination is an integral part of fluvial geomorphological research. The methods used to directly measure channel bed roughness often require an exact knowledge of grain size distributions of a given stream reach. In some cases this method is impractical, especially for large catchments and systems involving a large degree of form roughness. In this context, the determination of bed surface roughness using Terrestrial Laser Scanning (TLS) provides new possibilities. The application of laser scanning has been increasingly used recently for channel morphology research (Heritage & Hetherington 2007, Milan et al. 2007, Hodge et al. 2009). However, the use of TLS data to quantify bed surface roughness leads to new methodological problems. One of these problems is known as the 'Shading Effect'. Because of this, portions of the channel surface situated behind a large obstacle cannot be surveyed. Hence, the first goal of this study is to determine the minimum number of scanning positions to accurately characterize channel bed roughness. For roughness calculation, the investigation area is divided into an orthogonal grid. The question about this is: Which grid cell size should be chosen? In general, the cell size is defined by the largest particle in the test area. This requires sediment sampling and leads to additional field work. To avoid this, this study further assesses the importance of grid cell size on bed roughness calculation. The ultimate goal of this study is to improve the application of TLS for roughness calculation in gravel-bed rivers. For this purpose several channel reaches in two different study sites were surveyed with an ILRIS 36D. One investigation area is situated in the Reintal valley located in the northern limestone Alps (Wettersteingebirge) Bavaria/Germany. The other one is situated in the proglacial area of the

  4. Brain surface maps from 3-D medical images

    NASA Astrophysics Data System (ADS)

    Lu, Jiuhuai; Hansen, Eric W.; Gazzaniga, Michael S.

    1991-06-01

    The anatomic and functional localization of brain lesions for neurologic diagnosis and brain surgery is facilitated by labeling the cortical surface in 3D images. This paper presents a method which extracts cortical contours from magnetic resonance (MR) image series and then produces a planar surface map which preserves important anatomic features. The resultant map may be used for manual anatomic localization as well as for further automatic labeling. Outer contours are determined on MR cross-sectional images by following the clear boundaries between gray matter and cerebral-spinal fluid, skipping over sulci. Carrying this contour below the surface by shrinking it along its normal produces an inner contour that alternately intercepts gray matter (sulci) and white matter along its length. This procedure is applied to every section in the set, and the image (grayscale) values along the inner contours are radially projected and interpolated onto a semi-cylindrical surface with axis normal to the slices and large enough to cover the whole brain. A planar map of the cortical surface results by flattening this cylindrical surface. The projection from inner contour to cylindrical surface is unique in the sense that different points on the inner contour correspond to different points on the cylindrical surface. As the outer contours are readily obtained by automatic segmentation, cortical maps can be made directly from an MR series.

  5. Polarimetric thermal emission from rough surfaces

    NASA Technical Reports Server (NTRS)

    Johnson, J. T.; Kong, J. A.; Shin, R. T.; Staelin, D. H.; Yueh, S. H.; Nghiem, S. V.; Kwok, R.; Oneill, K.; Lohanick, A.

    1993-01-01

    Recent theoretical works have suggested the potential of passive polarimetry in the remote sensing of geophysical media. It was shown that the third Stokes parameter U of the thermal emission may become larger for azimuthally asymmetric fields of observation. In order to investigate the potential applicability of passive polarimetry to the remote sensing of ocean surface, measurements of the polarimetric thermal emission from a sinusoidal water surface and a numerical study of the polarimetric thermal emission from randomly rough ocean surfaces were performed. Measurements of sinusoidal water surface thermal emission were performed using a sinusoidal water surface which was created by placing a thin sheet of fiberglass with a sinusoidal profile in two dimensions extended infinitely in the third dimension onto a water surface. The theory of thermal emission from a 'two-layer' periodic surface is derived and the exact solution is performed using both the extended boundary condition method (EBC) and the method of moments (MOM). The theoretical predictions are found to be in good agreement with the experimental results once the effects of the radiometer antenna pattern are included and the contribution of background noise to the measurements is modeled. The experimental results show that the U parameter indicates the direction of periodicity of the water surface and can approach values of up to 30 K for the surface observed. Next, a numerical study of polarimetric thermal emission from randomly rough surfaces was performed. A Monte Carlo technique utilizing an exact method for calculating thermal emission was chosen for the study to avoid any of the limitations of the commonly used approximate methods in rough surface scattering. In this Monte Carlo technique, a set of finite rough surface profiles in two dimensions with desired statistics was generated and extended periodically. The polarimetric thermal emission from each surface of the set was then calculated using

  6. Surface Roughness Reduction on Divinylbenzene Foam Shells

    NASA Astrophysics Data System (ADS)

    Streit, Jon; Karnes, John; Motta, Brian; Petta, Nicole

    2009-11-01

    Inertial fusion energy targets for the Naval Research Laboratory's High Average Power Laser Program require millimeter-scale, low density foam capsules with a gas permeation barrier and an outer surface roughness less than 50 nm RMS. Divinylbenzene (DVB) foam is a candidate for the capsule wall material, but its porous, open celled surface has been both too rough and difficult to seal. To overcome this difficulty we have repurposed a previously reported dual stage initiator emulsion microencapsulation method, adding an additional step that enhances the surface of the foam capsules. Using both low and high temperature initiators allows the DVB foam to gel in the low temperature stage and a water soluble monomer to be added and polymerized during the high temperature stage without breaking down the emulsion. This method forms a submicron skin that covers the open celled DVB foam surface, resulting in a superior substrate for gas permeation barrier deposition.

  7. Boltzmann active walkers and rough surfaces

    NASA Astrophysics Data System (ADS)

    Pochy, R. D.; Kayser, D. R.; Aberle, L. K.; Lam, L.

    1993-06-01

    An active walker model (AWM) was recently proposed by Freimuth and Lam for the generation of various filamentary patterns. In an AWM, the walker changes the landscape as it walks, and its steps are in turn influenced by the changing landscape. The landscape so obtained is a rough surface. In this paper, the properties of such a rough surface (with average height conserved) generated by a Boltzmann active walker in 1 + 1 dimensions is investigated in detail. The scaling properties of the surface thickness σ T is found to belong to a new class quite different from other types of fractal surfaces. For example, σ T is independent of the system size L, but is a function of the “temperature” T. Soliton propagation is found when T = 0.

  8. Rough and Steep Terrain Lunar Surface Mobility

    NASA Technical Reports Server (NTRS)

    Wilcox, Brian

    2005-01-01

    In the summer of 2004, the NASA Exploration Systems Mission Directorate conducted an open call for projects relevant to human and robotic exploration of the Earth-Moon and Mars systems. A project entitled 'Rough and Steep Terrain Lunar Surface Mobility' was submitted by JPL and accepted by NASA. The principal investigator of this project describes the robotic vehicle being developed for this effort, which includes six 'wheels-on-legs' so that it can roll efficiently on relatively smooth terrain but walk (using locked wheels as footpads) when "the going gets rough".

  9. Rough Fresnel zone plates over metallic surfaces.

    PubMed

    Salgado-Remacha, Francisco Javier; Sanchez-Brea, Luis Miguel; Alvarez-Rios, Francisco Javier; Bernabeu, Eusebio

    2010-04-01

    We analyze the focusing properties of Fresnel zone plates fabricated over steel tapes using laser ablation. Our intention is to implement the use of micro-optical elements when the use of conventional chrome-glass elements is not indicated. Because of the manufacture process, the surface presents a certain anisotropic roughness, which reduces the focusing properties. First, we develop numerical simulations by means of the Rayleigh-Sommerfeld approach, showing how roughness in both levels of the Fresnel zone plate affects the focalization of the lens. We also manufacture Fresnel zone plates over steel tape, and perform experimental verification that corroborates the numerical results. PMID:20357856

  10. Surface roughness effects in elastohydrodynamic contacts

    NASA Technical Reports Server (NTRS)

    Tripp, J. H.; Hamrock, B. J.

    1985-01-01

    Surface roughness effects in full-film EHL contacts were studied. A flow factor modification to the Reynolds equation was applied to piezoviscous-elastic line contacts. Results for ensemble-averaged film shape, pressure distribution, and other mechanical quantities were obtained. Asperities elongated in the flow direction by a factor exceeding two decreased both film shape and pressure extrema at constant load; isotropic or transverse asperities increased these extrema. The largest effects are displayed by traction, which increased by over 5% for isotropic or transverse asperities and by slightly less for longitudinal roughness.

  11. Conveying the 3D Shape of Transparent Surfaces Via Texture

    NASA Technical Reports Server (NTRS)

    Interrante, Victoria; Fuchs, Henry; Pizer, Stephen

    1997-01-01

    Transparency can be a useful device for depicting multiple overlapping surfaces in a single image. The challenge is to render the transparent surfaces in such a way that their three-dimensional shape can be readily understood and their depth distance from underlying structures clearly perceived. This paper describes our investigations into the use of sparsely-distributed discrete, opaque texture as an 'artistic device' for more explicitly indicating the relative depth of a transparent surface and for communicating the essential features of its 3D shape in an intuitively meaningful and minimally occluding way. The driving application for this work is the visualization of layered surfaces in radiation therapy treatment planning data, and the technique is illustrated on transparent isointensity surfaces of radiation dose. We describe the perceptual motivation and artistic inspiration for defining a stroke texture that is locally oriented in the direction of greatest normal curvature (and in which individual strokes are of a length proportional to the magnitude of the curvature in the direction they indicate), and discuss several alternative methods for applying this texture to isointensity surfaces defined in a volume. We propose an experimental paradigm for objectively measuring observers' ability to judge the shape and depth of a layered transparent surface, in the course of a task relevant to the needs of radiotherapy treatment planning, and use this paradigm to evaluate the practical effectiveness of our approach through a controlled observer experiment based on images generated from actual clinical data.

  12. Depth propagation and surface construction in 3-D vision.

    PubMed

    Georgeson, Mark A; Yates, Tim A; Schofield, Andrew J

    2009-01-01

    In stereo vision, regions with ambiguous or unspecified disparity can acquire perceived depth from unambiguous regions. This has been called stereo capture, depth interpolation or surface completion. We studied some striking induced depth effects suggesting that depth interpolation and surface completion are distinct stages of visual processing. An inducing texture (2-D Gaussian noise) had sinusoidal modulation of disparity, creating a smooth horizontal corrugation. The central region of this surface was replaced by various test patterns whose perceived corrugation was measured. When the test image was horizontal 1-D noise, shown to one eye or to both eyes without disparity, it appeared corrugated in much the same way as the disparity-modulated (DM) flanking regions. But when the test image was 2-D noise, or vertical 1-D noise, little or no depth was induced. This suggests that horizontal orientation was a key factor. For a horizontal sine-wave luminance grating, strong depth was induced, but for a square-wave grating, depth was induced only when its edges were aligned with the peaks and troughs of the DM flanking surface. These and related results suggest that disparity (or local depth) propagates along horizontal 1-D features, and then a 3-D surface is constructed from the depth samples acquired. The shape of the constructed surface can be different from the inducer, and so surface construction appears to operate on the results of a more local depth propagation process. PMID:18977239

  13. Surface roughness scattering in multisubband accumulation layers

    NASA Astrophysics Data System (ADS)

    Fu, Han; Reich, K. V.; Shklovskii, B. I.

    2016-06-01

    Accumulation layers with very large concentrations of electrons where many subbands are filled became recently available due to ionic liquid and other new methods of gating. The low-temperature mobility in such layers is limited by the surface roughness scattering. However, theories of roughness scattering so far dealt only with the small-density single subband two-dimensional electron gas (2DEG). Here we develop a theory of roughness-scattering limited mobility for the multisubband large concentration case. We show that with growing 2D electron concentration n the surface dimensionless conductivity σ /(2 e2/h ) first decreases as ∝n-6 /5 and then saturates as ˜(d aB/Δ2)≫1 , where d and Δ are the characteristic length and height of the surface roughness and aB is the effective Bohr radius. This means that in spite of the shrinkage of the 2DEG thickness and the related increase of the scattering rate the 2DEG remains a good metal.

  14. Wenzel Wetting on Slippery Rough Surfaces

    NASA Astrophysics Data System (ADS)

    Stogin, Birgitt; Dai, Xianming; Wong, Tak-Sing

    2015-11-01

    Liquid repellency is an important surface property used in a wide range of applications including self-cleaning, anti-icing, anti-biofouling, and condensation heat transfer, and is characterized by apparent contact angle (θ*) and contact angle hysteresis (Δθ*). The Wenzel equation (1936) predicts θ* of liquids in the Wenzel state, and is one of the most fundamental equations in the wetting field. However, droplets in the Wenzel state on conventional rough surfaces exhibit large Δθ* , making it difficult to experimentally verify the model with precision. As a result, precise verification of the Wenzel wetting model has remained an open scientific question for the past 79 years. Here we introduce a new class of liquid-infused surfaces called slippery rough surfaces -- surfaces with significantly reduced Δθ* compared to conventional rough surfaces--and use them to experimentally assess the Wenzel equation with the highest precision to date. We acknowledge the funding support by National Science Foundation (NSF) CAREER Award #: 1351462 and Office of Navy Research MURI Award #: N00014-12-1-0875. Stogin acknowledges the support from the NSF Graduate Research Fellowship (Grant No. DGE1255832).

  15. Wetting on rough self-affine surfaces

    NASA Astrophysics Data System (ADS)

    Palasantzas, George

    1995-05-01

    In this paper, we present a general investigation of the effective potential for complete wetting on self-affine rough surfaces. The roughness effect is investigated by means of the height-height correlation model in Fourier space ~(1+aξ2q2)-1-H. The parameters H and ξ are, respectively, the roughness exponent and the substrate in-plane correlation length. It is observed that the effect of H on the free interface profile is significant for ξ>ξ) regime is characterized by a power-law scaling ~Y-2.

  16. THE THOMSON SURFACE. III. TRACKING FEATURES IN 3D

    SciTech Connect

    Howard, T. A.; DeForest, C. E.; Tappin, S. J.; Odstrcil, D.

    2013-03-01

    In this, the final installment in a three-part series on the Thomson surface, we present simulated observations of coronal mass ejections (CMEs) observed by a hypothetical polarizing white light heliospheric imager. Thomson scattering yields a polarization signal that can be exploited to locate observed features in three dimensions relative to the Thomson surface. We consider how the appearance of the CME changes with the direction of trajectory, using simulations of a simple geometrical shape and also of a more realistic CME generated using the ENLIL model. We compare the appearance in both unpolarized B and polarized pB light, and show that there is a quantifiable difference in the measured brightness of a CME between unpolarized and polarized observations. We demonstrate a technique for using this difference to extract the three-dimensional (3D) trajectory of large objects such as CMEs. We conclude with a discussion on how a polarizing heliospheric imager could be used to extract 3D trajectory information about CMEs or other observed features.

  17. Wear Analysis of Thermal Spray Coatings on 3D Surfaces

    NASA Astrophysics Data System (ADS)

    Tillmann, W.; Luo, W.; Selvadurai, U.

    2014-01-01

    Even though the application of thermal spray coatings on complex geometries gained a greater interest in the last decade, the effect of different geometrical features on the wear behavior is still ill-defined. In this study, the wear resistance of FTC-FeCSiMn coated 3D surfaces was investigated. The wear test was carried out by means of two innovative testing procedures. The first test is a Pin-on-Tubes test where the rotating motion is realized by a lathe chuck. The specimens in the second test were fixed on the table and a robot arm operated the pin. This wear test was applied on specimens with concave or convex surfaces. The residual stresses, which were determined by means of an incremental hole-drilling method, show a dependency on the substrate geometry. The obtained stresses were put in relation to the different radii. After the wear test, a 3D-profilometer determined the wear volume and the sections of the coatings were characterized by a scanning electron microscope. The results indicate that the wear resistance is strongly influenced by the geometry of the substrate.

  18. 3D Additive Construction with Regolith for Surface Systems

    NASA Technical Reports Server (NTRS)

    Mueller, Robert P.

    2014-01-01

    Planetary surface exploration on Asteroids, the Moon, Mars and Martian Moons will require the stabilization of loose, fine, dusty regolith to avoid the effects of vertical lander rocket plume impingement, to keep abrasive and harmful dust from getting lofted and for dust free operations. In addition, the same regolith stabilization process can be used for 3 Dimensional ( 3D) printing, additive construction techniques by repeating the 2D stabilization in many vertical layers. This will allow in-situ construction with regolith so that materials will not have to be transported from Earth. Recent work in the NASA Kennedy Space Center (KSC) Surface Systems Office (NE-S) Swamp Works and at the University of Southern California (USC) under two NASA Innovative Advanced Concept (NIAC) awards have shown promising results with regolith (crushed basalt rock) materials for in-situ heat shields, bricks, landing/launch pads, berms, roads, and other structures that could be fabricated using regolith that is sintered or mixed with a polymer binder. The technical goals and objectives of this project are to prove the feasibility of 3D printing additive construction using planetary regolith simulants and to show that they have structural integrity and practical applications in space exploration.

  19. 3D stochastic geophysical inversion for contact surface geometry

    NASA Astrophysics Data System (ADS)

    Lelièvre, Peter; Farquharson, Colin; Bijani, Rodrigo

    2015-04-01

    Geologists' interpretations about the Earth typically involve distinct rock units with contacts (interfaces) between them. As such, 3D geological Earth models typically comprise wireframe contact surfaces of tessellated triangles or other polygonal planar facets. In contrast, standard minimum-structure geophysical inversions are performed on meshes of space-filling cells (typically prisms or tetrahedra) and recover smoothly varying physical property distributions that are inconsistent with typical geological interpretations. There are several approaches through which mesh-based geophysical inversion can help recover models with some of the desired characteristics. However, a more effective strategy is to consider a fundamentally different type of inversion that works directly with models that comprise surfaces representing contacts between rock units. We are researching such an approach, our goal being to perform geophysical forward and inverse modelling directly with 3D geological models of any complexity. Geological and geophysical models should be specified using the same parameterization such that they are, in essence, the same Earth model. We parameterize the wireframe contact surfaces in a 3D model as the coordinates of the nodes (facet vertices). The physical properties of each rock unit in a model remain fixed while the geophysical inversion controls the position of the contact surfaces via the control nodes, perturbing the surfaces as required to fit the geophysical data responses. This is essentially a "geometry inversion", which can be used to recover the unknown geometry of a target body or to investigate the viability of a proposed Earth model. We apply global optimization strategies to solve the inverse problem, including stochastic sampling to obtain statistical information regarding the likelihood of particular features in the model, helping to assess the viability of a proposed model. Jointly inverting multiple types of geophysical data is simple

  20. Temperature maps measurements on 3D surfaces with infrared thermography

    NASA Astrophysics Data System (ADS)

    Cardone, Gennaro; Ianiro, Andrea; Dello Ioio, Gennaro; Passaro, Andrea

    2012-02-01

    The use of the infrared camera as a temperature transducer in wind tunnel applications is convenient and widespread. Nevertheless, the infrared data are available in the form of 2D images while the observed surfaces are often not planar and the reconstruction of temperature maps over them is a critical task. In this work, after recalling the principles of IR thermography, a methodology to rebuild temperature maps on the surfaces of 3D object is proposed. In particular, an optical calibration is applied to the IR camera by means of a novel target plate with control points. The proposed procedure takes also into account the directional emissivity by estimating the viewing angle. All the needed steps are described and analyzed. The advantages given by the proposed method are shown with an experiment in a hypersonic wind tunnel.

  1. Additive manufactured polymeric 3D scaffolds with tailored surface topography influence mesenchymal stromal cells activity.

    PubMed

    Neves, Sara C; Mota, Carlos; Longoni, Alessia; Barrias, Cristina C; Granja, Pedro L; Moroni, Lorenzo

    2016-06-01

    Additive manufactured three-dimensional (3D) scaffolds with tailored surface topography constitute a clear advantage in tissue regeneration strategies to steer cell behavior. 3D fibrous scaffolds of poly(ethylene oxide terephthalate)/poly(butylene terephthalate) block copolymer presenting different fiber surface features were successfully fabricated by additive manufacturing combined with wet-spinning, in a single step, without any post-processing. The optimization of the processing parameters, mainly driven by different solvent/non-solvent combinations, led to four distinct scaffold types, with average surface roughness values ranging from 0.071 ± 0.012 μm to 1.950 ± 0.553 μm, average pore sizes in the x- and y-axis between 351.1 ± 33.6 μm and 396.1 ± 32.3 μm, in the z-axis between 36.5 ± 5.3 μm and 70.7 ± 8.8 μm, average fiber diameters between 69.4 ± 6.1 μm and 99.0 ± 9.4 μm, and porosity values ranging from 60.2 ± 0.8% to 71.7 ± 2.6%. Human mesenchymal stromal cells (hMSCs) cultured on these scaffolds adhered, proliferated, and produced endogenous extracellular matrix. The effect of surface roughness and topography on hMSCs differentiation was more evident for cells seeded at lower density, where the percentage of cells in direct contact with the surface was higher compared to more densely seeded scaffolds. Under osteogenic conditions, lower surface roughness values (0.227 ± 0.035 μm) had a synergistic effect on hMSCs behavior, while chondrogenesis was favored on rougher surfaces (1.950 ± 0.553 μm). PMID:27219645

  2. Soil Surface Roughness through Image Analysis

    NASA Astrophysics Data System (ADS)

    Tarquis, A. M.; Saa-Requejo, A.; Valencia, J. L.; Moratiel, R.; Paz-Gonzalez, A.; Agro-Environmental Modeling

    2011-12-01

    Soil erosion is a complex phenomenon involving the detachment and transport of soil particles, storage and runoff of rainwater, and infiltration. The relative magnitude and importance of these processes depends on several factors being one of them surface micro-topography, usually quantified trough soil surface roughness (SSR). SSR greatly affects surface sealing and runoff generation, yet little information is available about the effect of roughness on the spatial distribution of runoff and on flow concentration. The methods commonly used to measure SSR involve measuring point elevation using a pin roughness meter or laser, both of which are labor intensive and expensive. Lately a simple and inexpensive technique based on percentage of shadow in soil surface image has been developed to determine SSR in the field in order to obtain measurement for wide spread application. One of the first steps in this technique is image de-noising and thresholding to estimate the percentage of black pixels in the studied area. In this work, a series of soil surface images have been analyzed applying several de-noising wavelet analysis and thresholding algorithms to study the variation in percentage of shadows and the shadows size distribution. Funding provided by Spanish Ministerio de Ciencia e Innovación (MICINN) through project no. AGL2010- 21501/AGR and by Xunta de Galicia through project no INCITE08PXIB1621 are greatly appreciated.

  3. Modeling superhydrophobic surfaces comprised of random roughness

    NASA Astrophysics Data System (ADS)

    Samaha, M. A.; Vahedi Tafreshi, H.; Gad-El-Hak, M.

    2011-11-01

    We model the performance of superhydrophobic surfaces comprised of randomly distributed roughness that resembles natural surfaces, or those produced via random deposition of hydrophobic particles. Such a fabrication method is far less expensive than ordered-microstructured fabrication. The present numerical simulations are aimed at improving our understanding of the drag reduction effect and the stability of the air-water interface in terms of the microstructure parameters. For comparison and validation, we have also simulated the flow over superhydrophobic surfaces made up of aligned or staggered microposts for channel flows as well as streamwise or spanwise ridge configurations for pipe flows. The present results are compared with other theoretical and experimental studies. The numerical simulations indicate that the random distribution of surface roughness has a favorable effect on drag reduction, as long as the gas fraction is kept the same. The stability of the meniscus, however, is strongly influenced by the average spacing between the roughness peaks, which needs to be carefully examined before a surface can be recommended for fabrication. Financial support from DARPA, contract number W91CRB-10-1-0003, is acknowledged.

  4. Microscopic Dimensions Engineering: Stepwise Manipulation of the Surface Wettability on 3D Substrates for Oil/Water Separation.

    PubMed

    Du, Ran; Gao, Xin; Feng, Qingliang; Zhao, Qiuchen; Li, Pan; Deng, Shibin; Shi, Liurong; Zhang, Jin

    2016-02-01

    Microscopic dimensions engineering is proposed to devise a series of 3D superhydrophobic substrates with microstructures of different dimensions. Combined theoretical modeling and experiments give the relationship of surface roughness and superhydrophobic properties, important for guiding the design of superior superwettable materials for water remediation and other uses. PMID:26618329

  5. Controlled implant/soft tissue interaction by nanoscale surface modifications of 3D porous titanium implants

    NASA Astrophysics Data System (ADS)

    Rieger, Elisabeth; Dupret-Bories, Agnès; Salou, Laetitia; Metz-Boutigue, Marie-Helene; Layrolle, Pierre; Debry, Christian; Lavalle, Philippe; Engin Vrana, Nihal

    2015-05-01

    Porous titanium implants are widely employed in the orthopaedics field to ensure good bone fixation. Recently, the use of porous titanium implants has also been investigated in artificial larynx development in a clinical setting. Such uses necessitate a better understanding of the interaction of soft tissues with porous titanium structures. Moreover, surface treatments of titanium have been generally evaluated in planar structures, while the porous titanium implants have complex 3 dimensional (3D) architectures. In this study, the determining factors for soft tissue integration of 3D porous titanium implants were investigated as a function of surface treatments via quantification of the interaction of serum proteins and cells with single titanium microbeads (300-500 μm in diameter). Samples were either acid etched or nanostructured by anodization. When the samples are used in 3D configuration (porous titanium discs of 2 mm thickness) in vivo (in subcutis of rats for 2 weeks), a better integration was observed for both anodized and acid etched samples compared to the non-treated implants. If the implants were also pre-treated with rat serum before implantation, the integration was further facilitated. In order to understand the underlying reasons for this effect, human fibroblast cell culture tests under several conditions (directly on beads, beads in suspension, beads encapsulated in gelatin hydrogels) were conducted to mimic the different interactions of cells with Ti implants in vivo. Physical characterization showed that surface treatments increased hydrophilicity, protein adsorption and roughness. Surface treatments also resulted in improved adsorption of serum albumin which in turn facilitated the adsorption of other proteins such as apolipoprotein as quantified by protein sequencing. The cellular response to the beads showed considerable difference with respect to the cell culture configuration. When the titanium microbeads were entrapped in cell

  6. Wetting failure of hydrophilic surfaces promoted by surface roughness

    PubMed Central

    Zhao, Meng-Hua; Chen, Xiao-Peng; Wang, Qing

    2014-01-01

    Wetting failure is of vital importance to many physical phenomena, such as industrial coating and drop emission. Here we show when and how the surface roughness promotes the destabilization of a moving contact line on a hydrophilic surface. Beyond the balance of the driving force and viscous resistance where a stable wetting interface is sustained, wetting failure occurs and is modified by the roughness of the surface. The promoting effect arises only when the wetting velocity is high enough to create a gas-liquid-solid composite interface in the vicinity of the moving contact line, and it is a function of the intrinsic contact angle and proportion of solid tops. We propose a model to explain splashes of rough solid spheres impacting into liquids. It reveals a novel concept that dynamic wetting on hydrophilic rough surfaces can be similar to that on hydrophobic surfaces, and brings a new way to design surfaces with specific wetting properties. PMID:24948390

  7. Enhancing capillary rise on a rough surface

    NASA Astrophysics Data System (ADS)

    Chow, Melissa; Wexler, Jason; Jacobi, Ian; Stone, Howard

    2014-11-01

    Liquid-infused surfaces have been proposed as a robust alternative to traditional air-cushioned superhydrophobic surfaces. However, if these surfaces are held vertically the lubricating oil can drain from the surface, and cause the surface to lose its novel properties. To examine this failure mode, we measure the drainage from a surface with model roughness that is scaled-up to allow for detailed measurements. We confirm that the bulk fluid drains from the surface until it reaches the level of the capillary rise height, although the detailed dynamics vary even in simple surface geometries. We then test different substrate architectures to explore how the roughness can be designed to retain greater amounts of oil. Supported under MRSEC NSF DMR 0819860 (PI: Prof. N. Phuan Ong) REU Site Grant: NSF DMR-1156422 (PI: Prof. Mikko Haataja), PREM CSUN Prime # NSF 1205734 and ONR MURI Grants N00014-12-1-0875 and N00014-12-1-0962 (Program Manager Dr. Ki-Han Kim).

  8. Flow over a Biomimetic Surface Roughness Microgeometry

    NASA Astrophysics Data System (ADS)

    Warncke Lang, Amy; Hidalgo, Pablo; Westcott, Matthew

    2006-11-01

    Certain species of sharks (e.g. shortfin mako and common hammerhead) have a skin structure that could result in a bristling of their denticles (scales) during increased swimming speeds (Bechert, D. W., Bruse, M., Hage, W. and Meyer, R. 2000, Fluid mechanics of biological surfaces and their technological application. Naturwissenschaften 80:157-171). This unique surface geometry results in a three-dimensional array of cavities* (d-type roughness geometry) forming within the surface and has been given the acronym MAKO (Micro-roughness Array for Kinematic Optimization). Possible mechanisms leading to drag reduction over the shark's body by this unique roughness geometry include separation control thereby reducing pressure drag, skin friction reduction (via the `micro-air bearing' effect first proposed by Bushnell (AIAA 83-0227)), as well as possible transition delay in the boundary layer. Initial work is confined to scaling up the geometry from 0.2 mm on the shark skin to 2 cm, with a scaling down in characteristic velocity from 10 - 20 m/s to 10 - 20 cm/s for laminar flow boundary layer water tunnel studies. Support for this research by NSF SGER grant CTS-0630489 and a University of Alabama RAC grant is gratefully acknowledged. * Patent pending.

  9. Quantifying surface roughness over debris covered ice

    NASA Astrophysics Data System (ADS)

    Quincey, Duncan; Rounce, David; Ross, Andrew

    2016-04-01

    Aerodynamic roughness length (z0) remains a major uncertainty when determining turbulent heat fluxes over glacier surfaces, and can vary by an order of magnitude even within a small area and through the melt season. Defining z0 over debris-covered ice is particularly complex, because the surface may comprise clasts of greatly varying size, and the broader-scale surface relief can be similarly heterogeneous. Several recent studies have used Structure from Motion to data model debris-covered surfaces at the centimetric scale and calculate z0 based on measurements of surface microtopography. However, few have validated these measurements with independent vertical wind profile measurements, or considered how the measurements vary over a range of different surface types or scales of analysis. Here, we present the results of a field investigation conducted on the debris covered Khumbu Glacier during the post-monsoon season of 2015. We focus on two sites. The first is characterised by gravels and cobbles supported by a fine sandy matrix. The second comprises cobbles and boulders separated by voids. Vertical profiles of wind speed measured over both sites enable us to derive measurements of aerodynamic roughness that are similar in magnitude, with z0 at the second site exceeding that at the first by < 1 cm. During our observation period, snow covered the second site for three days, but the impact on z0 is small, implying that roughness is predominantly determined by major rock size obstacles rather than the general form of the surface. To complement these aerodynamic measurements we also conducted a Structure from Motion survey across each patch and calculated z0 using microtopographic methods published in a range of recent studies. We compare the outputs of each of these algorithms with each other and with the aerodynamic measurements, assess how they perform over a range of scales, and evaluate the validity of using microtopographic methods where aerodynamic measurements

  10. Surface roughness of flat and curved optical surfaces

    NASA Technical Reports Server (NTRS)

    George, M. C.; Reddy, Bandi Jagannadha; Jagannath, H.; Perera, M.; Venkateswarlu, P.

    1989-01-01

    Surface roughness measurement has several applications. Even a few A roughness will cause scattered light in optical systems. Smooth surfaces are required in a wide variety of instruments. For example, the outputs of the high power lasers are limited by the surface roughness of mirrors and windows. Similarly, the information storage capacity of magnetic media is limited by the roughness of the surface. Roughness reduces the resolving power of optics and distorts images. The performance of certain thin film components in electronic industries is affected by the roughness on the film surface. X-ray astronomical telescopes require smooth curved surfaces. To improve the surface quality, super sensitive detection methods are required. Wide ranging measurement techniques are developed based on interferometry, electron microscopy, C-rays, ellipsometry, light scattering, and using mechanical stylus, etc. Though there are several techniques available for measurement and evaluation of the surfaces, no single technique is fully adequate. Also, the technique used should be nondestructive and highly sensitive. So, an optical heterodyne profilometer was fabricated. Its current sensitivity is much better than 10A rms. It is a noncontact and nondestructive technique. The instrument can be operated even by unskilled personnel for routine measurements.

  11. Colored 3D surface reconstruction using Kinect sensor

    NASA Astrophysics Data System (ADS)

    Guo, Lian-peng; Chen, Xiang-ning; Chen, Ying; Liu, Bin

    2015-03-01

    A colored 3D surface reconstruction method which effectively fuses the information of both depth and color image using Microsoft Kinect is proposed and demonstrated by experiment. Kinect depth images are processed with the improved joint-bilateral filter based on region segmentation which efficiently combines the depth and color data to improve its quality. The registered depth data are integrated to achieve a surface reconstruction through the colored truncated signed distance fields presented in this paper. Finally, the improved ray casting for rendering full colored surface is implemented to estimate color texture of the reconstruction object. Capturing the depth and color images of a toy car, the improved joint-bilateral filter based on region segmentation is used to improve the quality of depth images and the peak signal-to-noise ratio (PSNR) is approximately 4.57 dB, which is better than 1.16 dB of the joint-bilateral filter. The colored construction results of toy car demonstrate the suitability and ability of the proposed method.

  12. Application of a roughness-length representation to parameterize energy loss in 3-D numerical simulations of large rivers

    NASA Astrophysics Data System (ADS)

    Sandbach, S. D.; Lane, S. N.; Hardy, R. J.; Amsler, M. L.; Ashworth, P. J.; Best, J. L.; Nicholas, A. P.; Orfeo, O.; Parsons, D. R.; Reesink, A. J. H.; Szupiany, R. N.

    2012-12-01

    Recent technological advances in remote sensing have enabled investigation of the morphodynamics and hydrodynamics of large rivers. However, measuring topography and flow in these very large rivers is time consuming and thus often constrains the spatial resolution and reach-length scales that can be monitored. Similar constraints exist for computational fluid dynamics (CFD) studies of large rivers, requiring maximization of mesh- or grid-cell dimensions and implying a reduction in the representation of bedform-roughness elements that are of the order of a model grid cell or less, even if they are represented in available topographic data. These "subgrid" elements must be parameterized, and this paper applies and considers the impact of roughness-length treatments that include the effect of bed roughness due to "unmeasured" topography. CFD predictions were found to be sensitive to the roughness-length specification. Model optimization was based on acoustic Doppler current profiler measurements and estimates of the water surface slope for a variety of roughness lengths. This proved difficult as the metrics used to assess optimal model performance diverged due to the effects of large bedforms that are not well parameterized in roughness-length treatments. However, the general spatial flow patterns are effectively predicted by the model. Changes in roughness length were shown to have a major impact upon flow routing at the channel scale. The results also indicate an absence of secondary flow circulation cells in the reached studied, and suggest simpler two-dimensional models may have great utility in the investigation of flow within large rivers.

  13. Simulation of light transport in scintillators based on 3D characterization of crystal surfaces

    PubMed Central

    Cherry, Simon R.

    2013-01-01

    In the development of positron emission tomography (PET) detectors, understanding and optimizing scintillator light collection is critical for achieving high performance, particularly when the design incorporates depth-of-interaction (DOI) encoding or time-of-flight information. Monte-Carlo simulations play an important role in guiding research in detector designs and popular software such as GATE now include models of light transport in scintillators. Although current simulation toolkits are able to provide accurate models of perfectly polished surfaces, they do not successfully predict light output for other surface finishes, for example those often used in DOI-encoding detectors. The lack of accuracy of those models mainly originates from a simplified description of rough surfaces as an ensemble of micro-facets determined by the distribution of their normal, typically a Gaussian distribution. The user can specify the standard deviation of this distribution, but this parameter does not provide a full description of the surface reflectance properties. We propose a different approach based on 3D measurements of the surface using atomic force microscopy (AFM). Polished and rough (unpolished) crystals were scanned to compute the surface reflectance properties. The angular distributions of reflectance and reflected rays were computed and stored in look-up tables (LUTs). The LUTs account for the effect of incidence angle and were integrated in a light transport model. Crystals of different sizes were simulated with and without reflector. The simulated maximum light output and the light output as a function of DOI showed very good agreement with experimental characterization of the crystals, indicating that our approach provides an accurate model of polished and rough surfaces and could be used to predict light collection in scintillators. This model is based on a true 3D representation of the surface, makes no assumption about the surface and provides insight on the

  14. Quantifying the surface chemistry of 3D matrices in situ

    NASA Astrophysics Data System (ADS)

    Tzeranis, Dimitrios S.; So, Peter T. C.; Yannas, Ioannis V.

    2014-03-01

    Despite the major role of the matrix (the insoluble environment around cells) in physiology and pathology, there are very few and limited methods that can quantify the surface chemistry of a 3D matrix such as a biomaterial or tissue ECM. This study describes a novel optical-based methodology that can quantify the surface chemistry (density of adhesion ligands for particular cell adhesion receptors) of a matrix in situ. The methodology utilizes fluorescent analogs (markers) of the receptor of interest and a series of binding assays, where the amount of bound markers on the matrix is quantified via spectral multi-photon imaging. The study provides preliminary results for the quantification of the ligands for the two major collagen-binding integrins (α1β1, α2β1) in porous collagen scaffolds that have been shown to be able to induce maximum regeneration in transected peripheral nerves. The developed methodology opens the way for quantitative descriptions of the insoluble microenvironment of cells in physiology and pathology, and for integrating the matrix in quantitative models of cell signaling. α

  15. Investigations of Titan's topography and surface roughness

    NASA Astrophysics Data System (ADS)

    Sharma, Priyanka

    Saturn's moon, Titan is a geomorphologically active planetary object, and its surface is influenced by multiple processes like impact cratering, fluvial and aeolian erosion, lacustrine processes, tectonics, cryovolcanism and mantling. Disentangling the processes that compete to shape Titan's landscape is difficult in the absence of global topography data. In this thesis, I utilize techniques in topographic statistics, fractal theory, study of terrestrial analogs and landscape evolution modeling to characterize Titan's topography and surface roughness and investigate the relative roles of surface processes in sculpting its landscape. I mapped the shorelines of 290 North Polar Titanian lakes using the Cassini Synthetic Aperture Radar dataset. The fractal dimensions of the shorelines were calculated via the divider/ruler method and box-counting method, at length scales of (1--10) km and found to average 1.27 and 1.32, respectively. The inferred power-spectral exponent of Titan's topography was found to be ≤ 2, which is lower than the values obtained from the global topography of the Earth or Venus. In order to interpret fractal dimensions of Titan's shorelines in terms of the surficial processes at work, I repeated a similar statistical analysis with 114 terrestrial analogous lakes formed by different processes, using C-band radar backscatter data from the Shuttle Radar Topography Mission (SRTM). I found different lake generation mechanisms on Earth produce 'statistically different' shorelines; however, no specific set of processes could be identified for forming Titanian lake basins. Using the Cassini RADAR altimetry data, I investigated Titan's global surface roughness and calculated median absolute slopes, average relief and Hurst exponent (H) for the surface of Titan. I detected a clear trend with latitude in these roughness parameters. Equatorial regions had the smallest slopes, lowest values of H and smallest intra-footprint relief, compared to the mid

  16. Robust surface roughness indices and morphological interpretation

    NASA Astrophysics Data System (ADS)

    Trevisani, Sebastiano; Rocca, Michele

    2016-04-01

    Geostatistical-based image/surface texture indices based on variogram (Atkison and Lewis, 2000; Herzfeld and Higginson, 1996; Trevisani et al., 2012) and on its robust variant MAD (median absolute differences, Trevisani and Rocca, 2015) offer powerful tools for the analysis and interpretation of surface morphology (potentially not limited to solid earth). In particular, the proposed robust index (Trevisani and Rocca, 2015) with its implementation based on local kernels permits the derivation of a wide set of robust and customizable geomorphometric indices capable to outline specific aspects of surface texture. The stability of MAD in presence of signal noise and abrupt changes in spatial variability is well suited for the analysis of high-resolution digital terrain models. Moreover, the implementation of MAD by means of a pixel-centered perspective based on local kernels, with some analogies to the local binary pattern approach (Lucieer and Stein, 2005; Ojala et al., 2002), permits to create custom roughness indices capable to outline different aspects of surface roughness (Grohmann et al., 2011; Smith, 2015). In the proposed poster, some potentialities of the new indices in the context of geomorphometry and landscape analysis will be presented. At same time, challenges and future developments related to the proposed indices will be outlined. Atkinson, P.M., Lewis, P., 2000. Geostatistical classification for remote sensing: an introduction. Computers & Geosciences 26, 361-371. Grohmann, C.H., Smith, M.J., Riccomini, C., 2011. Multiscale Analysis of Topographic Surface Roughness in the Midland Valley, Scotland. IEEE Transactions on Geoscience and Remote Sensing 49, 1220-1213. Herzfeld, U.C., Higginson, C.A., 1996. Automated geostatistical seafloor classification - Principles, parameters, feature vectors, and discrimination criteria. Computers and Geosciences, 22 (1), pp. 35-52. Lucieer, A., Stein, A., 2005. Texture-based landform segmentation of LiDAR imagery

  17. 3D Printing of Molecular Potential Energy Surface Models

    ERIC Educational Resources Information Center

    Lolur, Phalgun; Dawes, Richard

    2014-01-01

    Additive manufacturing, commonly known as 3D printing, is gaining popularity in a variety of applications and has recently become routinely available. Today, 3D printing services are not only found in engineering design labs and through online companies, but also in university libraries offering student access. In addition, affordable options for…

  18. Effect of a 3D surface depression on boundary layer transition

    NASA Astrophysics Data System (ADS)

    Xu, Hui; Mughal, Shahid; Sherwin, Spencer J.

    2015-11-01

    The influence of a three-dimensional surface depression on the transitional boundary layer is investigated numerically. In the boundary layer transition, the primary mode is a Tollmien-Schlichting (TS) wave which is a viscous instability. These modes are receptive to surface roughness interacting with free stream disturbances and/or surface vibrations. In this paper, numerical calculations are carried out to investigate the effect of the depression on instability of the boundary layer. In order to implement linear analysis, two/three (2D/3D)-dimensional nonlinear Navier-Stokes equations are solved by spectral element method to generate base flows in a sufficient large domain. The linear analyses are done by the parabolic stability equations (PSE). Finally, a DNS calculation is done to simulate the boundary layer transition.

  19. Measuring surface topography with scanning electron microscopy. I. EZEImage: a program to obtain 3D surface data.

    PubMed

    Ponz, Ezequiel; Ladaga, Juan Luis; Bonetto, Rita Dominga

    2006-04-01

    Scanning electron microscopy (SEM) is widely used in the science of materials and different parameters were developed to characterize the surface roughness. In a previous work, we studied the surface topography with fractal dimension at low scale and two parameters at high scale by using the variogram, that is, variance vs. step log-log graph, of a SEM image. Those studies were carried out with the FERImage program, previously developed by us. To verify the previously accepted hypothesis by working with only an image, it is indispensable to have reliable three-dimensional (3D) surface data. In this work, a new program (EZEImage) to characterize 3D surface topography in SEM has been developed. It uses fast cross correlation and dynamic programming to obtain reliable dense height maps in a few seconds which can be displayed as an image where each gray level represents a height value. This image can be used for the FERImage program or any other software to obtain surface topography characteristics. EZEImage also generates anaglyph images as well as characterizes 3D surface topography by means of a parameter set to describe amplitude properties and three functional indices for characterizing bearing and fluid properties. PMID:17481354

  20. Surface modified alginate microcapsules for 3D cell culture

    NASA Astrophysics Data System (ADS)

    Chen, Yi-Wen; Kuo, Chiung Wen; Chueh, Di-Yen; Chen, Peilin

    2016-06-01

    Culture as three dimensional cell aggregates or spheroids can offer an ideal platform for tissue engineering applications and for pharmaceutical screening. Such 3D culture models, however, may suffer from the problems such as immune response and ineffective and cumbersome culture. This paper describes a simple method for producing microcapsules with alginate cores and a thin shell of poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) to encapsulate mouse induced pluripotent stem (miPS) cells, generating a non-fouling surface as an effective immunoisolation barrier. We demonstrated the trapping of the alginate microcapsules in a microwell array for the continuous observation and culture of a large number of encapsulated miPS cells in parallel. miPS cells cultured in the microcapsules survived well and proliferated to form a single cell aggregate. Droplet formation of monodisperse microcapsules with controlled size combined with flow cytometry provided an efficient way to quantitatively analyze the growth of encapsulated cells in a high-throughput manner. The simple and cost-effective coating technique employed to produce the core-shell microcapsules could be used in the emerging field of cell therapy. The microwell array would provide a convenient, user friendly and high-throughput platform for long-term cell culture and monitoring.

  1. Understanding EUV mask blank surface roughness induced LWR and associated roughness requirement

    SciTech Connect

    Yan, Pei-Yang; Zhang, Guojing; Gullickson, Eric M.; Goldberg, Kenneth A.; Benk, Markus P.

    2015-03-01

    Extreme ultraviolet lithography (EUVL) mask multi-layer (ML) blank surface roughness specification historically comes from blank defect inspection tool requirement. Later, new concerns on ML surface roughness induced wafer pattern line width roughness (LWR) arise. In this paper, we have studied wafer level pattern LWR as a function of EUVL mask surface roughness via High-NA Actinic Reticle Review Tool. We found that the blank surface roughness induced LWR at current blank roughness level is in the order of 0.5nm 3σ for NA=0.42 at the best focus. At defocus of ±40nm, the corresponding LWR will be 0.2nm higher. Further reducing EUVL mask blank surface roughness will increase the blank cost with limited benefit in improving the pattern LWR, provided that the intrinsic resist LWR is in the order of 1nm and above.

  2. Terahertz NDE for Metallic Surface Roughness Evaluation

    NASA Technical Reports Server (NTRS)

    Madaras, Eric I.; Anastasi, Robert F.

    2006-01-01

    Metallic surface roughness in a nominally smooth surface is a potential indication of material degradation or damage. When the surface is coated or covered with an opaque dielectric material, such as paint or insulation, then inspecting for surface changes becomes almost impossible. Terahertz NDE is a method capable of penetrating the coating and inspecting the metallic surface. The terahertz frequency regime is between 100 GHz and 10 THz and has a free space wavelength of 300 micrometers at 1 THz. Pulsed terahertz radiation, can be generated and detected using optical excitation of biased semiconductors with femtosecond laser pulses. The resulting time domain signal is 320 picoseconds in duration. In this application, samples are inspected with a commercial terahertz NDE system that scans the sample and generates a set of time-domain signals that are a function of the backscatter from the metallic surface. Post processing is then performed in the time and frequency domains to generate C-scan type images that show scattering effects due to surface non-uniformity.

  3. Mathematical Modeling of Surface Roughness of Castings Produced Using ZCast Direct Metal Casting

    NASA Astrophysics Data System (ADS)

    Chhabra, M.; Singh, R.

    2015-04-01

    Aim of this investigation is to develop a mathematical model for predicting surface roughness of castings produced using ZCast process by employing Buckingham's π-theorem. A relationship has been proposed between surface roughness of castings and shell wall thickness of the shell moulds fabricated using 3D printer. Based on model, experiments were performed to obtain the surface roughness of aluminium, brass and copper castings produced using ZCast process based on 3D printing technique. Based on experimental data, three best fitted third-degree polynomial equations have been established for predicting the surface roughness of castings. The predicted surface roughness values were then calculated using established best fitted equations. An error analysis was performed to compare the experimental and predicted data. The average prediction errors obtained for aluminium, brass and copper castings are 10.6, 2.43 and 3.12 % respectively. The obtained average surface roughness (experimental and predicted) values of castings produced are acceptable with the sand cast surface roughness values range (6.25-25 µm).

  4. Subsurface Sounding of Mars: The Effects of Surface Roughness

    NASA Technical Reports Server (NTRS)

    Plaut, J. J.; Jordan, R.; Safaeinili, A.; Safaenelli, A.; Seu, R.; Orosei, R.

    2001-01-01

    The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) will conduct a global survey of Mars from the Mars Express Orbiter starting in 2004. The primary objective of the subsurface observations is to detect material interfaces in the upper several kilometers of the crust of Mars, with a particular emphasis on mapping the 3D distribution of water and ice in that portion of the crust. In order to detect subsurface interfaces, the returned echo from the subsurface must be distinguished from noise and clutter, which can arise from a variety of sources. One source of clutter is surface topography that generates backscattered energy at the same time delay as the subsurface region of interest. Surface topography can affect the detectability of subsurface features in several other ways. Surface roughness at scales comparable or somewhat smaller than the radar wavelength reduces the coherency of the wave as it passes the upper interface. Also, surface slope (tilt) at scales of the radar footprint and larger (> 5 km) affects the apparent Doppler signature of the echoes, and effectively disperses the wave transmitted into the subsurface, making processing and interpretation difficult. In this paper, we report on the roughness characteristics of Mars at these various scales as measured by the Mars Global Surveyor Laser Altimeter (MOLA), and consider the implications for achieving the subsurface sounding goals of MARSIS. Additional information is contained in the original extended abstract.

  5. Study of 3-D Dynamic Roughness Effects on Flow Over a NACA 0012 Airfoil Using Large Eddy Simulations at Low Reynolds Numbers

    NASA Astrophysics Data System (ADS)

    Guda, Venkata Subba Sai Satish

    There have been several advancements in the aerospace industry in areas of design such as aerodynamics, designs, controls and propulsion; all aimed at one common goal i.e. increasing efficiency --range and scope of operation with lesser fuel consumption. Several methods of flow control have been tried. Some were successful, some failed and many were termed as impractical. The low Reynolds number regime of 104 - 105 is a very interesting range. Flow physics in this range are quite different than those of higher Reynolds number range. Mid and high altitude UAV's, MAV's, sailplanes, jet engine fan blades, inboard helicopter rotor blades and wind turbine rotors are some of the aerodynamic applications that fall in this range. The current study deals with using dynamic roughness as a means of flow control over a NACA 0012 airfoil at low Reynolds numbers. Dynamic 3-D surface roughness elements on an airfoil placed near the leading edge aim at increasing the efficiency by suppressing the effects of leading edge separation like leading edge stall by delaying or totally eliminating flow separation. A numerical study of the above method has been carried out by means of a Large Eddy Simulation, a mathematical model for turbulence in Computational Fluid Dynamics, owing to the highly unsteady nature of the flow. A user defined function has been developed for the 3-D dynamic roughness element motion. Results from simulations have been compared to those from experimental PIV data. Large eddy simulations have relatively well captured the leading edge stall. For the clean cases, i.e. with the DR not actuated, the LES was able to reproduce experimental results in a reasonable fashion. However DR simulation results show that it fails to reattach the flow and suppress flow separation compared to experiments. Several novel techniques of grid design and hump creation are introduced through this study.

  6. Experimental Investigation of the Problem of Surface Roughness

    NASA Technical Reports Server (NTRS)

    Schlichting, H

    1937-01-01

    Based on the universal laws of turbulent velocity distribution at rough and smooth walls, there is in the present work presented a method that allows surface roughness tests and in particular, measurements on the roughness of ship surfaces to be carried out in a much simpler manner. The types of roughness investigated were in the form of flat, rough plates installed in a square-section rectangular channel, the other three walls always being smooth. Twenty-one plates of various roughness were investigated, the roughness elements being the following: spheres of diameter 0.41 and 0.21, respectively, spherical segments, cones, and "short" and "long" angles.

  7. Surface roughness of anodized titanium coatings.

    SciTech Connect

    Dugger, Michael Thomas; Chinn, Douglas Alan

    2010-10-01

    Samples of grade five 6Al4V titanium alloy were coated with two commercial fluoropolymer anodizations (Tiodize and Canadize) and compared. Neither coating demonstrates significant outgassing. The coatings show very similar elemental analysis, except for the presence of lead in the Canadize coating, which may account for its lower surface friction in humid environments. Surface roughness has been compared by SEM, contact profilometry, optical profilometry, power spectral density and bidirectional scattering distribution function (BSDF). The Tiodize film is slightly smoother by all measurement methods, but the Canadize film shows slightly less scatter at all angles of incidence. Both films exhibited initial friction coefficients of 0.2 to 0.4, increasing to 0.4 to 0.8 after 1000 cycles of sliding due to wear of the coating and ball. The coatings are very similar and should behave identically in most applications.

  8. Meaningful surface roughness and quality tolerances

    NASA Astrophysics Data System (ADS)

    Aikens, David M.

    2010-08-01

    Most tolerances on optical elements can be derived or calculated from the application requirements using computeraided optical design programs. For surface quality and surface roughness, however, there are few guidelines or tools for calculating appropriate tolerances. Typically, we simply use a legacy specification (e.g. 60-40 and 3 A RMS) with little thought for either the cost of achieving the specification or the penalty for failing to achieve it. Often these legacy specifications are ambiguous, unnecessarily costly and in some cases completely meaningless. This paper provides some basic rules and equations for calculation of the real or perceived impact of these specifications, and some guidelines for the initiate (and for some of us veterans as well) as to how to compose a meaningful tolerance.

  9. Investigation on three-dimensional surface roughness evaluation of engineering ceramic for rotary ultrasonic grinding machining

    NASA Astrophysics Data System (ADS)

    Wei, Shiliang; Zhao, Hong; Jing, Juntao

    2015-12-01

    Surface roughness has considerable influence on its quality and function of products in precision and ultra-precision machining, and the same situation applies to engineering ceramic for rotary ultrasonic grinding machining (RUGM). This paper presents a new parameter, called fractal root mean square deviation, for evaluating engineering ceramic three-dimensional (3D) surface roughness of RUGM. Based on engineering ceramics surface of RUGM is typical isotropic, the mathematical model of fractal root mean square deviation was established, and it possesses double characteristics of absolute measurement and multi-scale. Then validation has been implemented, and fractal root mean square deviation is superior to evaluate engineering ceramic 3D surface roughness with better resolution and sensitivity. Furthermore, the relationship between main factor parameters and fractal root mean square deviation was proposed. The evaluation parameter and the results could be implemented in practice to get higher quality surface.

  10. Surface roughness and infrared emission from the lunar surface

    NASA Astrophysics Data System (ADS)

    Vogler, Karl Joseph

    1994-01-01

    In order to understand thermal infrared spectra of the moon and solid-surfaced planetary bodies in terms of surface roughness and composition, a two-part project involving thermophysical computer models and infrared photometry has been pursued. The computer models calculate the infrared radiation emitted by an atmosphereless body with a macroscopically rough surface using radiative heat transfer methods. Multiple scattering of incident solar radiation, and multiple scattering and remission of thermal infrared radiation onto surrounding surface elements are included in the model. Surface roughness is modeled as paraboloidal holes characterized by a fractional coverage of a spherical object and a single depth-to-diameter ratio. Thermal emission from the rough surface is anisotropic and deviates from a gray body emission assumed by standard thermal models. The model explains to first-order published, mid infrared, measurements of the moon and Galilean Satellites. Surface composition is included by using results from Hapke for reflectance and emittance properties of a particulate surface. It is concluded that negative surface relief is required to explain the continuum behavior of the lunar thermal spectrum. An infrared photometer was constructed from an existing design and was configured in order to perform whole disk photometry of the moon at various phase angles. Measurements at 5.03, 8.4 and 11.5 micron were made at seven phase angles, ranging from -151 deg 55 min to 53 deg 27 min. The thermophysical computer models were modified so that disk-integrated emission as a function of phase angle could be calculated. Effects due to thermal inertia of the surface are not included in this simplified version of the model. The model calculations compare favorably with measurements of the moon made by the author, Sarri and Shorthill and Murdock. It is concluded that surface roughness is necessary in explaining the shape of the lunar thermal emission with phase angle.

  11. Interactions between surface roughness and airflow turbulence affecting drying dynamics of rough porous surfaces

    NASA Astrophysics Data System (ADS)

    Haghighi, Erfan; Kirchner, James; Or, Dani

    2016-04-01

    Evaporative drying of porous surfaces interacting with turbulent airflows is common in various industrial and natural applications. The intrinsic relief and roughness of natural porous surfaces are likely to influence the structure of interacting turbulent airflow boundary layers, and thus affect rates and patterns of heat and vapor fluxes from the surface. These links have been formalized in new mechanistic models that consider intermittent and localized turbulence-induced boundary layers, resulting in rich surface evaporation and energy exchange dynamics. The models were evaluated experimentally by systematically varying surface roughness elements in drying experiments of wavy and bluff-body covered sand surfaces in a wind tunnel. Thermal infrared signatures of localized evaporative fluxes as well as mean evaporative mass losses were recorded. The resulting patterns were in good agreement with model predictions for local and surface averaged turbulent exchange rates. Experimental and theoretical results suggest that evaporative water losses from wavy sand surfaces can be either enhanced or suppressed (relative to a flat surface), due to the complex interplay between the local boundary layer thickness and internal limitations on water flow to the evaporating surface. For sand surfaces covered by isolated cylindrical elements (bluff bodies), model predictions and measurements show persistent enhancement of evaporative fluxes from bluff-rough surfaces compared to a flat surface under similar conditions. This enhancement is attributed to the formation of vortices that thin the boundary layer over part of the interacting surface footprint. The implications of this study for interpreting and upscaling evapotranspiration rates from terrestrial surfaces will be discussed.

  12. Speckle pattern texture analysis method to measure surface roughness

    NASA Astrophysics Data System (ADS)

    Kuznetsov, I.; Sadovoy, A.; Doronin, A.; Meglinski, I.

    2013-02-01

    Speckle pattern texture analysis method is applied to measure surface roughness of human skin. The method is based on analyzing of a gray level co-occurrence matrix occurred from a speckle image of a rough surface. Paper with different surface roughness is used as a skin phantom. The roughness is controlled by profilometry measurements. The developed methodology could find wide application in dermatology and tissue diagnostics.

  13. Thermodynamics of capillary adhesion between rough surfaces.

    PubMed

    de Boer, M P; de Boer, P C T

    2007-07-01

    According to the Dupré equation, the work of adhesion is equal to the surface energy difference in the separated versus the joined materials minus an interfacial energy term. However, if a liquid is at the interface between two solid materials, evaporation or condensation takes place under equilibrium conditions. The resulting matter exchange is accompanied by heat flow, and can reduce or increase the work of adhesion. Accounting for the energies requires an open-system control volume analysis based on the first law of thermodynamics. Depending on whether evaporation or condensation occurs during separation, a work term that is negative or positive must be added to the surface energy term to calculate the work of adhesion. We develop and apply this energy balance to several different interface geometries and compare the work of adhesion to the surface energy created. The model geometries include a sphere on a flat with limiting approximations and also with an exact solution, a circular disc, and a combination of these representing a rough interface. For the sphere on a flat, the work of adhesion is one half the surface energy created if equilibrium is maintained during the pull-off process. PMID:17368659

  14. Theory of adhesion: Role of surface roughness

    NASA Astrophysics Data System (ADS)

    Persson, B. N. J.; Scaraggi, M.

    2014-09-01

    We discuss how surface roughness influences the adhesion between elastic solids. We introduce a Tabor number which depends on the length scale or magnification, and which gives information about the nature of the adhesion at different length scales. We consider two limiting cases relevant for (a) elastically hard solids with weak (or long ranged) adhesive interaction (DMT-limit) and (b) elastically soft solids with strong (or short ranged) adhesive interaction (JKR-limit). For the former cases we study the nature of the adhesion using different adhesive force laws (F ˜ u-n, n = 1.5-4, where u is the wall-wall separation). In general, adhesion may switch from DMT-like at short length scales to JKR-like at large (macroscopic) length scale. We compare the theory predictions to results of exact numerical simulations and find good agreement between theory and simulation results.

  15. Focus Variation - A New Technology for High Resolution Optical 3D Surface Metrology

    NASA Astrophysics Data System (ADS)

    Scherer, S.

    2009-04-01

    Focus Variation - A New Technology for High Resolution Optical 3D Surface Metrology S. Scherer1, E. Cristea1, O. Huber1, A. Krenn1 1 ALICONA GmbH Graz, Austria The need for increasing accuracy is a characteristic of all geo-applications, and hence of the instruments contributing to obtaining relevant data. Small and fine sensors are being developed, measuring different parameters of our geosystem and requiring continuous validation and calibration. These sensors have often very small components (fine sensors able to sense dust, atmospheric water vapour characteristics, pressure change, gravimeters, satellite micro-components), showing complex topographies including steep flanks and having varying reflective properties. In order to get valid and reliable results, quality assurance of these instruments and sensors is required. The optical technology Focus-Variation, developed by Alicona and added in the latest draft of the upcoming ISO standard 25178, provides high resolution 3D surface metrology even at those complex topographies. The technique of Focus-Variation combines the small depth of focus of an optical system with vertical scanning to provide topographical and color information from the variation of focus. It is used for high-resolution optical 3D surface measurements. The traceable and repeatable measurement results are further being used for calibration and validation purposes. Some of the characteristics of the technology are: - Measurement of instruments / samples with steep flanks up to 80° - Measurement of materials with strongly varying reflection properties - Measurement of surfaces presenting fine (from 10nm) or strong roughness Here, we present the operating principle and possible applications of the optical 3D measurement system "InfiniteFocus", which is based on the technology of Focus-Variation and used for quality assurance in the lab and in production. With the vertical resolution of up to 10nm, InfiniteFocus yields meaningful form and

  16. Effect of surface roughness on EPES and AREPES measurements: Flat and crenels silicon surfaces

    NASA Astrophysics Data System (ADS)

    Chelda, S.; Robert-Goumet, C.; Gruzza, B.; Bideux, L.; Monier, G.

    2008-06-01

    EPES (elastic peak electron spectroscopy) and AREPES (angle resolved elastic peak electron spectroscopy) are non destructive methods and very sensitive to the surface region. These techniques allow to measure the percentage ηe of elastically backscattered electrons from the surface excited by an electron beam. Both methods are combined with Monte-Carlo (MC) simulations to interpret experimental results. In this work, we underline the importance of a micrometric scale roughness at the surface. The use of an original Monte-Carlo method was fruitful for the simulation, moreover 3D representations have been developed for visualization and qualitative interpretation of the results. For a more precise quantitative study, a 2D representation was necessary. The calculated results have been compared with published experimental ones got for different incidence angles and primary energies, on a silicon surface having triangular saw-tooth aspect (crenels) obtained by photolithography. We have observed that the effect due to the roughness increases with the incidence angle.

  17. Incorporating Skew into RMS Surface Roughness Probability Distribution

    NASA Technical Reports Server (NTRS)

    Stahl, Mark T.; Stahl, H. Philip.

    2013-01-01

    The standard treatment of RMS surface roughness data is the application of a Gaussian probability distribution. This handling of surface roughness ignores the skew present in the surface and overestimates the most probable RMS of the surface, the mode. Using experimental data we confirm the Gaussian distribution overestimates the mode and application of an asymmetric distribution provides a better fit. Implementing the proposed asymmetric distribution into the optical manufacturing process would reduce the polishing time required to meet surface roughness specifications.

  18. Automated assessment of renal cortical surface roughness from computerized tomography images and its association with age

    PubMed Central

    Duan, Xinhui; Rule, Andrew D.; Elsherbiny, Hisham E.; Vrtiska, Terri J.; Avula, Ramesh T.; Alexander, Mariam P.; Lerman, Lilach O.; McCollough, Cynthia H.

    2014-01-01

    Rationale and Objectives Nephrosclerosis occurs with aging and is characterized by increased kidney sub-capsular surface irregularities at autopsy. Assessments of cortical roughness in-vivo could provide an important measure of nephrosclerosis. The purpose of this study was to develop and validate an image-processing algorithm for quantifying renal cortical surface roughness in-vivo and determine its association with age. Materials and methods Renal cortical surface roughness was measured on contrast-enhanced abdominal CT images of potential living kidney donors. A roughness index was calculated based on geometric curvature of each kidney from 3D images, and compared with visual observation scores. Cortical roughness was compared between the oldest and youngest donors, and its interaction with cortical volume and age assessed. Results The developed quantitative roughness index identified significant differences in kidneys with visual surface roughness scores of 0 (minimal), 1 (mild), and 2 (moderate) (p<0.001) in a random sample of 200 potential kidney donors. Cortical roughness was significantly higher in the 94 oldest (64–75y) versus 91 youngest (18–25y) potential kidney donors (p<0.001). Lower cortical volume was associated with older age but not with roughness (r=−0.03, p=0.75). The association of oldest age group with roughness (OR=1.8 per SD of roughness index) remained significant after adjustment for total cortex volume (OR=2.0 per SD of roughness index). Conclusion A new algorithm to measure renal cortical surface roughness from CT scans detected rougher surface in older compared to younger kidneys, independent of cortical volume loss. This novel index may allow quantitative evaluation of nephrosclerosis in vivo using contrast-enhanced CT. PMID:25086950

  19. 3D surface topography study of the biofunctionalized nanocrystalline Ti-6Zr-4Nb/Ca-P

    SciTech Connect

    Jakubowicz, J.; Adamek, G.; Jurczyk, M.U.; Jurczyk, M.

    2012-08-15

    In this work surface of the sintered Ti-6Zr-4Nb nanocrystalline alloy was electrochemically biofunctionalized. The porous surface was produced by anodic oxidation in 1 M H{sub 3}PO{sub 4} + 2%HF electrolyte at 10 V for 30 min. Next the calcium-phosphate (Ca-P) layer was deposited, onto the formed porous surface, using cathodic potential - 5 V kept for 60 min in 0.042 M Ca(NO{sub 3}){sub 2} + 0.025 M (NH{sub 4}){sub 2}HPO{sub 4} + 0.1 M HCl electrolyte. The deposited Ca-P layer anchored in the pores. The biofunctionalized surface was studied by XRD, SEM and EDS. In vitro tests culture of normal human osteoblast (NHOst) cells showed very good cells proliferation, colonization and multilayering. Using optical profiler, roughness and hybrid 3D surface topography parameters were estimated. Correlation between surface composition, morphology, roughness and biocompatibility results was done. It has been shown by us that surface with appropriate chemical composition and topography, after combined electrochemical anodic and cathodic surface treatment, supports osteoblast adhesion and proliferation. 3D topography measurements using optical profiler play a key role in the biomaterials surface analysis. - Highlights: Black-Right-Pointing-Pointer Nanocrystalline Ti-6Zr-4Nb/Ca-P material was produced for hard tissue implant applications. Black-Right-Pointing-Pointer Calcium-phosphate results in surface biofunctionalization. Black-Right-Pointing-Pointer The biofunctionalized surface shows good in-vitro behavior.

  20. 3D SEM for surface topography quantification - a case study on dental surfaces

    NASA Astrophysics Data System (ADS)

    Glon, F.; Flys, O.; Lööf, P.-J.; Rosén, B.-G.

    2014-03-01

    3D analysis of surface topography is becoming a more used tool for industry and research. New ISO standards are being launched to assist in quantifying engineering surfaces. The traditional optical measuring instrumentation used for 3D surface characterization has been optical interferometers and confocal based instrumentation. However, the resolution here is limited in the lateral dimension to the wavelength of visible light to about 500 nm. The great advantage using the SEM for topography measurements is the high flexibility to zoom from low magnifications and locating interesting areas to high magnification of down to nanometer large surface features within seconds. This paper presents surface characterization of dental implant micro topography. 3D topography data was created from SEM images using commercial photogrammetric software. A coherence scanning interferometer was used for reference measurements to compare with the 3D SEM measurements on relocated areas. As a result of this study, measurements emphasizes that the correlation between the accepted CSI measurements and the new technology represented by photogrammetry based on SEM images for many areal characterization parameters are around or less than 20%. The importance of selecting sampling and parameter sensitivity to varying sampling is high-lighted. Future work includes a broader study of limitations of the photogrammetry technique on certified micro-geometries and more application surfaces at different scales.

  1. i3DP, a robust 3D printing approach enabling genetic post-printing surface modification.

    PubMed

    Wang, Xiaolong; Cai, Xiaobing; Guo, Qiuquan; Zhang, Tengyuan; Kobe, Brad; Yang, Jun

    2013-10-01

    Initiator integrated 3D printing, namely i3DP, was developed by incorporating a vinyl-terminated initiator into UV curable resin to make functional structural materials that enable genetic post-printing surface-initiated modification. Taking advantage of 3D printing and surface-initiated ATRP, the feasible i3DP makes 3D printed complex architectures possible for nearly any desired surface modification for various applications, for example, even pouring water into a sieve was readily achieved. PMID:24002351

  2. Surface roughness analysis after machining of direct laser deposited tungsten carbide

    NASA Astrophysics Data System (ADS)

    Wojciechowski, S.; Twardowski, P.; Chwalczuk, T.

    2014-03-01

    In this paper, an experimental surface roughness analysis in machining of tungsten carbide is presented. The tungsten carbide was received using direct laser deposition technology (DLD). Experiments carried out included milling of tungsten carbide samples using monolithic torus cubic boron nitride (CBN) tool and grinding with the diamond cup wheel. The effect of machining method on the generated surface topography was analysed. The 3D surface topographies were measured using optical surface profiler. The research revealed, that surface roughness generated after the machining of tungsten carbide is affected by feed per tooth (fz) value related to kinematic-geometric projection only in a minor extent. The main factor affecting machined surface roughness is the occurrence of micro grooves and protuberances on the machined surface, as well as other phenomena connected, inter alia, with the mechanism for material removal.

  3. Evolution of 3D surface imaging systems in facial plastic surgery.

    PubMed

    Tzou, Chieh-Han John; Frey, Manfred

    2011-11-01

    Recent advancements in computer technologies have propelled the development of 3D imaging systems. 3D surface-imaging is taking surgeons to a new level of communication with patients; moreover, it provides quick and standardized image documentation. This article recounts the chronologic evolution of 3D surface imaging, and summarizes the current status of today's facial surface capturing technology. This article also discusses current 3D surface imaging hardware and software, and their different techniques, technologies, and scientific validation, which provides surgeons with the background information necessary for evaluating the systems and knowledge about the systems they might incorporate into their own practice. PMID:22004854

  4. Backscatter from a periodic rough surface at near grazing incidence

    NASA Technical Reports Server (NTRS)

    Dominek, A. K.; Shamansky, H. T.

    1987-01-01

    The effect of periodic surface roughness on the radar cross section (RCS) was studied. The surface roughness was formed by a small sinusoidal variation in a planar surface. RCS measurements were obtained for two different sinusoidal variations near grazing incidence for both principle polarizations. Significant grating lobes were observed in the measurements which directly correspond to the roughness characteristics. A physical optics solution was generated and compared to the measurements with reasonable agreement.

  5. Fast 3D Surface Extraction 2 pages (including abstract)

    SciTech Connect

    Sewell, Christopher Meyer; Patchett, John M.; Ahrens, James P.

    2012-06-05

    Ocean scientists searching for isosurfaces and/or thresholds of interest in high resolution 3D datasets required a tedious and time-consuming interactive exploration experience. PISTON research and development activities are enabling ocean scientists to rapidly and interactively explore isosurfaces and thresholds in their large data sets using a simple slider with real time calculation and visualization of these features. Ocean Scientists can now visualize more features in less time, helping them gain a better understanding of the high resolution data sets they work with on a daily basis. Isosurface timings (512{sup 3} grid): VTK 7.7 s, Parallel VTK (48-core) 1.3 s, PISTON OpenMP (48-core) 0.2 s, PISTON CUDA (Quadro 6000) 0.1 s.

  6. Validation of 3D surface reconstruction of vertebrae and spinal column using 3D ultrasound data--a pilot study.

    PubMed

    Nguyen, Duc V; Vo, Quang N; Le, Lawrence H; Lou, Edmond H M

    2015-02-01

    Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformity of spine associated with vertebra rotation. The Cobb angle and axial vertebral rotation are important parameters to assess the severity of scoliosis. However, the vertebral rotation is seldom measured from radiographs due to time consuming. Different techniques have been developed to extract 3D spinal information. Among many techniques, ultrasound imaging is a promising method. This pilot study reported an image processing method to reconstruct the posterior surface of vertebrae from 3D ultrasound data. Three cadaver vertebrae, a Sawbones spine phantom, and a spine from a child with AIS were used to validate the development. The in-vitro result showed the surface of the reconstructed image was visually similar to the original objects. The dimension measurement error was <5 mm and the Pearson correlation was >0.99. The results also showed a high accuracy in vertebral rotation with errors of 0.8 ± 0.3°, 2.8 ± 0.3° and 3.6 ± 0.5° for the rotation values of 0°, 15° and 30°, respectively. Meanwhile, the difference in the Cobb angle between the phantom and the image was 4° and the vertebral rotation at the apex was 2°. The Cobb angle measured from the in-vivo ultrasound image was 4° different from the radiograph. PMID:25550193

  7. Soil surface roughness characterization for microwave remote sensing applications

    NASA Astrophysics Data System (ADS)

    Marzahn, P.; Rieke-Zapp, D.; Ludwig, R.

    2012-04-01

    With this poster we present a simple and efficient method to measure soil surface roughness in an agricultural environment. Micro scale soil surface roughness is a crucial parameter in many environmental applications. In recent studies it is strongly recognized that soil surface roughness significantly influences the backscatter of agricultural surface, especially on bare fields. Indeed, while different roughness indices depend on their measurement length, no satisfying roughness parametrization and measurement technique has been found yet, introducing large uncertainty in the interpretation of the radar backscattering. In this study, we introduce a photogrammetric system which consists of a customized consumer grade Canon EOS 5d camera and a reference frame providing ground control points. With the system one can generate digital surface models (DSM) with a minimum size of 1 x 2.5 m2, extendable to any desired size, with a ground x,y- resolution of 2 mm. Using this approach, we generated a set of DSM with sizes ranging from 2.5 m2 to 22 m2, acquired over different roughness conditions representing ploughed, harrowed as well as crusted fields on different test sites. For roughness characterization we calculated in microwave remote sensing common roughness indices such as the RMS- height s and the autocorrelation length l. In an extensive statistical investigation we show the behavior of the roughness indices for different acquisition sizes of the proposed method. Results indicate, compared to results from profiles generated out of the dataset, that using a three dimensional measuring device, the calculated roughness indices are more robust in their estimation. In addition, a strong directional dependency of the proposed roughness indices was observed which could be related to the orientation of the seedbed rows to the acqusition direction. In a geostatistical analysis, we decomposed the acquired roughness indices into different scales, yielding a roughness quantity

  8. Quantification of soil surface roughness evolution under simulated rainfall

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil surface roughness is commonly identified as one of the dominant factors governing runoff and interrill erosion. The objective of this study was to compare several existing soil surface roughness indices and to test the Revised Triangular Prism surface area Method (RTPM) as a new approach to cal...

  9. Physically-based Ice Thickness and Surface Roughness Retrievals over Rough Deformed Sea Ice

    NASA Astrophysics Data System (ADS)

    Li, Li; Gaiser, Peter; Allard, Richard; Posey, Pamela; Hebert, David; Richter-Menge, Jacqueline; Polashenski, Christopher; Claffey, Keran

    2016-04-01

    The observations of sea ice thickness and ice surface roughness are critical for our understanding of the state of the changing Arctic. Currently, the Radar and/or LiDAR data of sea ice freeboard are used to infer sea ice thickness via isostasy. The underlying assumption is that the LiDAR signal returns at the air/snow interface and radar signal at the snow/ice interface. The elevations of these interfaces are determined based on LiDAR/Radar return waveforms. However, the commonly used threshold-based surface detection techniques are empirical in nature and work well only over level/smooth sea ice. Rough sea ice surfaces can modify the return waveforms, resulting in significant Electromagnetic (EM) bias in the estimated surface elevations, and thus large errors in the ice thickness retrievals. To understand and quantify such sea ice surface roughness effects, a combined EM rough surface and volume scattering model was developed to simulate radar returns from the rough sea ice 'layer cake' structure. A waveform matching technique was also developed to fit observed waveforms to a physically-based waveform model and subsequently correct the roughness induced EM bias in the estimated freeboard. This new EM Bias Corrected (EMBC) algorithm was able to better retrieve surface elevations and estimate the surface roughness parameter simultaneously. Both the ice thickness and surface roughness retrievals are validated using in-situ data. For the surface roughness retrievals, we applied this EMBC algorithm to co-incident LiDAR/Radar measurements collected during a Cryosat-2 under-flight by the NASA IceBridge missions. Results show that not only does the waveform model fit very well to the measured radar waveform, but also the roughness parameters derived independently from the LiDAR and radar data agree very well for both level and deformed sea ice. For sea ice thickness retrievals, validation based on in-situ data from the coordinated CRREL/NRL field campaign demonstrates

  10. 3D Surface Profile and Color Stability of Tooth Colored Filling Materials after Bleaching

    PubMed Central

    Irawan, Bryant Anthony; Irawan, Stacey Natalie; Masudi, Sam'an Malik; Sukminingrum, Ninin; Alam, Mohammad Khursheed

    2015-01-01

    This study aims to evaluate the effects of vital tooth bleaching with carbamide peroxide home bleaching and in-office bleaching on the color stability and 3D surface profile of dental restorative filling materials. Thirty discs (n = 30) measure 6 mm in diameter and 2 mm thick for each of three restorative materials. These are nanofilled composite Filtek Z350 XT, the submicron composite Estelite Σ Quick, and nanofilled glass ionomer Ketac N100 nanoionomer and were fabricated in shade A2. Each group was further divided into three subgroups (n = 10): subgroup A (Opalescence PF), subgroup B (Opalescence Boost in-office bleaching), and subgroup C (distilled water) serving as control. Samples were bleached according to the manufacturer's instructions for a period of two weeks. The Commission Internationale de L'Eclairage (CIE L*, a*, b*) system was chosen for image processing, while 3D surface profile was tested with atomic force microscopy (AFM). Statistical analyses were performed with the Mann-Whitney tests and Krusal-Wallis with a P value of ≤0.05. The three restorative materials showed significant color changes (ΔE); P ≤ 0.05. In diminishing order, the mean color changes recorded were Estelite Σ (3.82 ± 1.6) > Ketac Nano (2.97 ± 1.2) > Filtek Z350 XT (2.25 ± 1.0). However, none of the tested materials showed statistically significant changes in surface roughness; P > 0.05. PMID:26558267

  11. Effect of surface roughness pattern on transient mixed elastohydrodynamic lubrication

    NASA Astrophysics Data System (ADS)

    Torabi, Amir; Akbarzadeh, Saleh; Salimpour, Mohammad Reza; Taei, Morteza

    2016-03-01

    Besides the surface roughness of two contacting surfaces, the surface roughness pattern i.e. longitudinal, transverse and isotropic significantly influences the tribological performance of the mechanical element. Their impression is more pronounced under the mixed elasto-hydrodynamic lubrication condition. The cam and flat follower mechanism is a typical sample in which adverse tribological conditions, including direct boundary interactions occurs. In this paper, the effect of surface roughness pattern on the film thickness and friction coefficient in a cam follower mechanism is investigated. Asperity interaction and friction coefficient analysis is conducted based on a novel elasto-plastic model. The lubrication model is qualitatively compared with the experimental results obtained from the pin on disk experiments for various surface roughness orientations. The results of transient lubrication analysis for a cam and follower lubrication problem are presented. It is shown that the longitudinal surface roughness pattern has a more desirable tribological performance than transverse surface pattern.

  12. APPROXIMATION OF SURFACES IN QUANTITATIVE 3-D RECONSTRUCTIONS

    EPA Science Inventory

    In serial section reconstructions a series of planar profiles are taken representing curves on the surface of the structure to be reconstructed. or a number of quantitative serial section methods, approximation of a surface is done by the formation of tiles between points of adja...

  13. Characteristics of surface roughness associated with leading edge ice accretion

    NASA Technical Reports Server (NTRS)

    Shin, Jaiwon

    1994-01-01

    Detailed size measurements of surface roughness associated with leading edge ice accretions are presented to provide information on characteristics of roughness and trends of roughness development with various icing parameters. Data was obtained from icing tests conducted in the Icing Research Tunnel (IRT) at NASA Lewis Research Center (LeRC) using a NACA 0012 airfoil. Measurements include diameters, heights, and spacing of roughness elements along with chordwise icing limits. Results confirm the existence of smooth and rough ice zones and that the boundary between the two zones (surface roughness transition region) moves upstream towards stagnation region with time. The height of roughness grows as the air temperature and the liquid water content increase, however, the airspeed has little effect on the roughness height. Results also show that the roughness in the surface roughness transition region grows during a very early stage of accretion but reaches a critical height and then remains fairly constant. Results also indicate that a uniformly distributed roughness model is only valid at a very initial stage of the ice accretion process.

  14. Tuning 3D topography on biomimetic surface for efficient self-cleaning and microfluidic manipulation

    NASA Astrophysics Data System (ADS)

    Guan, Wei-Sheng; Huang, Han-Xiong; Chen, An-Fu

    2015-03-01

    Currently, micro-/nanotopography on polymeric replica is generally limited to 2D when a mechanical demolding approach is applied. In this work, one-step replication of bio-inspired 3D topography is achieved using microinjection compression molding with novel dual-layer molds. Using a proposed flexible template, the replica topography and wettability are highly tunable during molding. Moreover, dual-scale topography on the mold is developed by coating the micropatterned insert with submicron silica particles. Contact angle and roll-off angle measurements indicate the lotus leaf, rose petal and rice leaf effects on biomimetic surfaces. Among the three kinds of surfaces, the petal-inspired surface possesses the superior performance in self-cleaning submicron contaminants and mechanical robustness, which is highly correlated to the low roughness-induced adhesive superhydrophobicity and the absence of fragile submicron-/nanostructure, respectively. Furthermore, a multi-layer mold structure is proposed for fabricating the open microfluidic devices. The embedment of the hydrophilic and hydrophobic silica particles in the microstructured open channel and the hydrophobic silica particles in the background area during replication renders the wettability contrast sharp, realizing the self-driven flow of microfluid confined within the open microchannel.

  15. Droplet morphologies on particles with macroscopic surface roughness.

    PubMed

    Stepánek, Frantisek; Rajniak, Pavol

    2006-01-31

    The equilibrium configuration of liquid droplets on the surface of macroscopically rough solid particles was determined by numerical simulations using the volume-of-fluid (VOF) method. The fractional surface coverage of the particle as a function of the droplet size, equilibrium contact angle, and the particle surface roughness amplitude and correlation length has been systematically investigated. Droplet size and contact angle were found to generally have a stronger effect on surface coverage than particle surface roughness. Because of droplet coalescence, a relatively large variation in surface coverage was observed for any given total liquid volume, particularly for larger values of the equilibrium contact angle. PMID:16430249

  16. Visual Short-Term Memory Benefit for Objects on Different 3-D Surfaces

    ERIC Educational Resources Information Center

    Xu, Yaoda; Nakayama, Ken

    2007-01-01

    Visual short-term memory (VSTM) plays an important role in visual cognition. Although objects are located on different 3-dimensional (3-D) surfaces in the real world, how VSTM capacity may be influenced by the presence of multiple 3-D surfaces has never been examined. By manipulating binocular disparities of visual displays, the authors found that…

  17. Diffuse scattered field of elastic waves from randomly rough surfaces using an analytical Kirchhoff theory

    NASA Astrophysics Data System (ADS)

    Shi, F.; Lowe, M. J. S.; Xi, X.; Craster, R. V.

    2016-07-01

    We develop an elastodynamic theory to predict the diffuse scattered field of elastic waves by randomly rough surfaces, for the first time, with the aid of the Kirchhoff approximation (KA). Analytical expressions are derived incorporating surface statistics, to represent the expectation of the angular distribution of the diffuse intensity for different modes. The analytical solutions are successfully verified with numerical Monte Carlo simulations, and also validated by comparison with experiments. We then apply the theory to quantitatively investigate the effects of the roughness and the shear-to-compressional wave speed ratio on the mode conversion and the scattering intensity, from low to high roughness within the valid region of KA. Both the direct and the mode converted intensities are significantly affected by the roughness, which leads to distinct scattering patterns for different wave modes. The mode conversion effect is very strong around the specular angle and it is found to increase as the surface appears to be more rough. In addition, the 3D roughness induced coupling between the out-of-plane shear horizontal (SH) mode and the in-plane modes is studied. The intensity of the SH mode is shown to be very sensitive to the out-of-plane correlation length, being influenced more by this than by the RMS value of the roughness. However, it is found that the depolarization pattern for the diffuse field is independent of the actual value of the roughness.

  18. Surface roughness evolution of nanocomposite thin films

    SciTech Connect

    Turkin, A. A.; Pei, Y. T.; Shaha, K. P.; Chen, C. Q.; Vainshtein, D. I.; Hosson, J. Th. M. de

    2009-01-01

    An analysis of dynamic roughening and smoothening mechanisms of thin films grown with pulsed-dc magnetron sputtering is presented. The roughness evolution has been described by a linear stochastic equation, which contains the second- and fourth-order gradient terms. Dynamic smoothening of the growing interface is explained by ballistic effects resulting from impingements of ions to the growing thin film. These ballistic effects are sensitive to the flux and energy of impinging ions. The predictions of the model are compared with experimental data, and it is concluded that the thin film roughness can be further controlled by adjusting waveform, frequency, and width of dc pulses.

  19. Surface-Area-Based Attribute Filtering in 3D

    NASA Astrophysics Data System (ADS)

    Kiwanuka, Fred N.; Ouzounis, Georgios K.; Wilkinson, Michael H. F.

    In this paper we describe a rotation-invariant attribute filter based on estimating the sphericity or roundness of objects by efficiently computing surface area and volume of connected components. The method is based on an efficient algorithm to compute all iso-surfaces of all nodes in a Max-Tree. With similar properties to moment-based attributes like sparseness, non-compactness, and elongation, our sphericity attribute can supplement these in finding blood-vessels in time-of-flight MR angiograms. We compare the method to a discrete surface area method based on adjacency, which has been used for urinary stone detection. Though the latter is faster, it is less accurate, and lacks rotation invariance.

  20. Rough surface improves stability of air- sounding balloons

    NASA Technical Reports Server (NTRS)

    Scoggins, J. R.

    1965-01-01

    Aerodynamic stability of balloons used for measuring the intensity and direction of atmospheric winds at various elevations is improved by incorporating a rough surface on the balloons. The rough-surfaced balloon is useful for collecting wind profiles and other meteorological data.

  1. Counterintuitive MCNPX Results for Scintillator Surface Roughness Effect

    SciTech Connect

    2012-08-12

    We have reported on our recent MCNPX simulation results of energy deposition for a group of 8 scintillation detectors, coupled with various rough surface patterns. The MCNPX results generally favored the detectors with various rough surface patterns. The observed MCNPX results are not fully explained by this work.

  2. Fine tuning the roughness of powder blasted surfaces

    NASA Astrophysics Data System (ADS)

    Wensink, Henk; Schlautmann, Stefan; Goedbloed, Martijn H.; Elwenspoek, Miko C.

    2002-09-01

    Powder blasting (abrasive jet machining) has recently been introduced as a bulk-micromachining technique for brittle materials. The surface roughness that is created with this technique is much higher (with a value of Ra between 1-2.5 μm) compared to general micromachining techniques. In this paper we study the roughness of powder blasted glass surfaces, and show how it depends on the process parameters. The roughness can also be changed after blasting by HF etching or by using a high-temperature anneal step. Roughness measurements and scanning electron microscopy images show the quantitative and qualitative changes in roughness. These post-processes will allow us to investigate the influence of surface roughness on the microsystem performance in future research.

  3. Effect of fracture surface roughness on shear crack growth

    SciTech Connect

    Gross, T.S.; Watt, D.W. . Dept. of Mechanical Engineering); Mendelsohn, D.A. . Dept. of Engineering Mechanics)

    1992-12-01

    A model of fracture surface interference for Mode I fatigue crack profiles was developed and evaluated. Force required to open the crack faces is estimated from point contact expressions for Mode I stress intensity factor. Force transfer across contacting asperities is estimated and used to calculate Mode II resistance stress intensity factor (applied factor is sum of effective and resistance factors). Electro-optic holographic interferometry was used to measure 3-D displacement field around a Mode I fatigue pre-crack in Al loaded in Mode II shear. Induced Mode I crack face displacements were greater than Mode II displacements. Plane stress shear lip caused displacement normal to surface as the crack faces are displaced. Algorithms are being developed to track the displacements associated with the original coordinate system in the camera. A 2-D boundary element method code for mixed mode I and II loading of a rough crack (sawtooth asperity model) has been completed. Addition of small-scale crack tip yielding and a wear model are completed and underway, respectively.

  4. Flow Measurements over a Biomimetic Surface Roughness Microgeometry

    NASA Astrophysics Data System (ADS)

    Lang, Amy; Hidalgo, Pablo; Westcott, Matthew

    2007-11-01

    Certain species of sharks (e.g. shortfin mako) have a skin structure that results in a bristling of their denticles (scales) during increased swimming speeds. This unique surface geometry results in the formation of a 3D array of cavities* (d-type roughness geometry) within the shark skin, thus causing it to potentially act as a means of boundary layer control. Initial work is confined to scaling up the geometry from 0.2 mm on the shark skin to 2 cm, with a scaling down in characteristic velocity from 10 - 20 m/s to 10 - 20 cm/s for laminar flow boundary layer water tunnel studies over a shark skin model. The hypothesized formation of cavity vortices within the shark skin replica has been measured using DPIV. We have also shown that with the sufficient growth of a boundary layer upstream of the model (local Re = 200,000), transition is not tripped by the surface and the flow skips over the cavities. Support for this research by a NSF SGER grant (CTS-0630489), Lindbergh Foundation Grant and a University of Alabama RAC grant is gratefully acknowledged. * Patent pending.

  5. Prediction of Frictional Drag over Rough Walls using Surface Statistics

    NASA Astrophysics Data System (ADS)

    Flack, Karen; Schultz, Michael

    2014-11-01

    Although the frictional drag of rough-wall-bounded flows has been studied extensively, several practical questions remain largely unresolved. First, the relationship between the shape of the roughness function in transitionally-rough regime and the surface topography which gives rise to it are not well understood. Second, it is not completely clear which textural parameters best describe a rough surface in a hydraulic sense. Furthermore, the range of roughness wavelengths that influence the skin-friction is not well established. The focus of the present work is to attempt to address these questions with a systematic study of the skin-friction of fifteen rough surfaces that were generated by grit blasting. The hydrodynamic tests were carried out over a large Reynolds number range. Five surfaces were prepared by grit blasting with a single scale blast media. These underwent hydrodynamic testing and were subsequently blasted with secondary and tertiary scale media in order to investigate the role that the incorporation of additional roughness length scales plays in determining the shape of the roughness function and the resulting hydraulic length scale. The presentation will focus on the appropriate statistical scales for prediction of the roughness function. Spatial filtering prior to the calculation of surface statistics will also be discussed. Work supported by the Office of Naval Research.

  6. Scattering of light by molecules over a rough surface.

    PubMed

    Long, Maureen; Khine, Michelle; Kim, Arnold D

    2010-05-01

    We present a theory for the multiple scattering of light by obstacles situated over a rough surface. This problem is important for applications in biological and chemical sensors. To keep the formulation of this theory simple, we study scalar waves. This theory requires knowledge of the scattering operator (t-matrix) for each of the obstacles as well as the reflection operator for the rough surface. The scattering operator gives the field scattered by the obstacle due to an exciting field incident on the scatterer. The reflection operator gives the field reflected by the rough surface due to an exciting field incident on the rough surface. We apply this general theory for the special case of point scatterers and a slightly rough surface with homogeneous Dirichlet and Neumann boundary conditions. We show examples that demonstrate the utility of this theory. PMID:20448766

  7. Emergent surface superconductivity in a 3D topological insulator

    NASA Astrophysics Data System (ADS)

    Krusin-Elbaum, Lia

    Surfaces of three-dimensional topological insulators have emerged as one of the most remarkable states of condensed quantum matter where exotic charge and spin phases of Dirac particles could form. This work reports on novel mesoscopic superconductivity in the topological insulator Sb2Te3 with transition to zero resistance induced through a minor tuning of growth chemistry that depletes bulk conduction channels. The depletion shifts Fermi energy towards the Dirac point as witnessed by a factor of 300 reduction of bulk carrier density and by the largest carrier mobility (>25, 000 cm2V-1s-1) found in any topological material of this class. Direct evidence from transport, the unprecedentedly large diamagnetic screening, and the presence of ~ 25 meV gaps detected by scanning tunneling spectroscopy reveal the superconducting condensate to emerge first in surface puddles at unexpectedly high temperature of ~ 50 K, with the onset of global phase coherence at ~ 9 K. The unconventional spin response of Sb2Te3 and the presence of subsurface 2DEG quantum well states arising from charge transfer to the surface are likely to play a role in the emergent superconducting state. The rich structure of this state lends itself to manipulation via growth conditions and the material parameters such as Fermi velocity and mean free path. This work was supported by NSF DMR-1122594, DMR-1420634, DMR-1322483, and DOD-W911NF-13-1-0159.

  8. The 3D flow structures generated by a pair of cubic roughness elements in a turbulent channel flow resolved using holographic microscopy

    NASA Astrophysics Data System (ADS)

    Gao, Jian; Katz, Joseph

    2015-11-01

    In studies of turbulent flows over rough walls, considerable efforts have been put on the overall effects of roughness parameters such as roughness height and spatial arrangement on the mean profiles and turbulence statistics. However there is very little experimental data on the generation, evolution, and interaction among roughness-initiated turbulent structures, which are essential for elucidating the near-wall turbulence production. As a first step, we approach this problem experimentally by applying digital holographic microscopy (DHM) to measure the flow and turbulence around a pair of cubic roughness elements embedded in the inner part of a high Reynolds number turbulent channel flow (Reτ = 2000 - 5000). The ratio of half-channel height (h) to cube height (a) is 25, and the cubes are aligned in the spanwise direction, and separated by 1.5 a. DHM provides high-resolution three-dimensional (3D) three-component (3C) velocity distributions. The presentation discusses methods to improve the data accuracy, both during the hologram acquisition and particle tracking phases. First, we compare and mutually validate velocity fields obtained from a two-view DHM system. Subsequently, during data processing, the seven criteria used for particle tracking is validated and augmented by planar tracking of particle image projections. Sample results reveal instantaneous 3D velocity fields and vortical structures resolved in fine details of several wall units. Funded by NSF and ONR.

  9. Superhydrophobic PDMS surfaces with three-dimensional (3D) pattern-dependent controllable adhesion

    NASA Astrophysics Data System (ADS)

    Yong, Jiale; Yang, Qing; Chen, Feng; Zhang, Dongshi; Du, Guangqing; Bian, Hao; Si, Jinhai; Yun, Feng; Hou, Xun

    2014-01-01

    In this paper, we demonstrate an effective approach for the three-dimensional (3D) pattern-structured superhydrophobic PDMS surfaces with controllable adhesion by using femtosecond laser etching method. By combining different laser power with a multi-layered etching way, various 3D patterns can be fabricated (for example, convex triangle array, round pit array, cylindrical array, convex rhombus array and concave triangle-cone array). The as-prepared surfaces with 3D patterns show superhydrophobic character and water controllable adhesion that range from ultralow to ultrahigh by designing different 3D patterns, on which the sliding angle can be controlled from 1° to 90° (the water droplet is firmly pinned on the superhydrophobic surface without any movement at any tilted angles). The 3D pattern-dependent adhesive property is attributed to the different contact modes. This work will provide a facile and promising strategy for the adhesion adjustment on superhydrophobic surfaces.

  10. To 3D or Not to 3D, That Is the Question: Do 3D Surface Analyses Improve the Ecomorphological Power of the Distal Femur in Placental Mammals?

    PubMed Central

    Gould, Francois D. H.

    2014-01-01

    Improvements in three-dimensional imaging technologies have renewed interest in the study of functional and ecological morphology. Quantitative approaches to shape analysis are used increasingly to study form-function relationships. These methods are computationally intensive, technically demanding, and time-consuming, which may limit sampling potential. There have been few side-by-side comparisons of the effectiveness of such approaches relative to more traditional analyses using linear measurements and ratios. Morphological variation in the distal femur of mammals has been shown to reflect differences in locomotor modes across clades. Thus I tested whether a geometric morphometric analysis of surface shape was superior to a multivariate analysis of ratios for describing ecomorphological patterns in distal femoral variation. A sample of 164 mammalian specimens from 44 genera was assembled. Each genus was assigned to one of six locomotor categories. The same hypotheses were tested using two methods. Six linear measurements of the distal femur were taken with calipers, from which four ratios were calculated. A 3D model was generated with a laser scanner, and analyzed using three dimensional geometric morphometrics. Locomotor category significantly predicted variation in distal femoral morphology in both analyses. Effect size was larger in the geometric morphometric analysis than in the analysis of ratios. Ordination reveals a similar pattern with arboreal and cursorial taxa as extremes on a continuum of morphologies in both analyses. Discriminant functions calculated from the geometric morphometric analysis were more accurate than those calculated from ratios. Both analysis of ratios and geometric morphometric surface analysis reveal similar, biologically meaningful relationships between distal femoral shape and locomotor mode. The functional signal from the morphology is slightly higher in the geometric morphometric analysis. The practical costs of conducting these

  11. Modelling of surface roughness effects on impurity erosion and deposition in TEXTOR with a code package SURO/ERO/SDPIC

    NASA Astrophysics Data System (ADS)

    Dai, Shuyu; Kirschner, A.; Sun, Jizhong; Tskhakaya, D.; Wang, Dezhen

    2014-12-01

    The roughness-induced uneven erosion-deposition behaviour is widely observed on plasma-wetted surfaces in tokamaks. The three-dimensional (3D) angular distribution of background plasma and impurities is expected to have an impact on the local erosion-deposition characteristic on rough surfaces. The investigations of 13C deposition on rough surfaces in TEXTOR experiments have been re-visited by 3D treatment of surface morphology to evaluate the effect of 3D angular distribution and its connection with surface topography by the code package SURO/ERO/SDPIC. The simulation results show that the erosion/deposition patterns and evolution of surface topography are strongly affected by the azimuthal direction of incident flux. A reduced aspect ratio of rough surface leads to an increase in 13C deposition due to the enhanced trapping ability at surface recessions. The shadowing effect of rough surface has been revealed based on the relationship between 3D incident direction and surface topography properties. The more realistic surface structures used by 3D SURO can well reproduce the experimental results of the increase in the 13C deposition efficiency by a factor of 3-5 on a rough surface compared with a smooth one. The influence of sheath electric field on the local impact angle and resulting 13C deposition has been studied, which indicates that the difference in 13C deposition caused by sheath electric field can be alleviated by the use of more realistic surface structures. The difference in 13C deposition on smooth graphite and tungsten substrates has been specified by consideration of effects of kinetic reflection, enhanced physical sputtering and nucleation.

  12. Determining Surface Roughness in Urban Areas Using Lidar Data

    NASA Technical Reports Server (NTRS)

    Holland, Donald

    2009-01-01

    An automated procedure has been developed to derive relevant factors, which can increase the ability to produce objective, repeatable methods for determining aerodynamic surface roughness. Aerodynamic surface roughness is used for many applications, like atmospheric dispersive models and wind-damage models. For this technique, existing lidar data was used that was originally collected for terrain analysis, and demonstrated that surface roughness values can be automatically derived, and then subsequently utilized in disaster-management and homeland security models. The developed lidar-processing algorithm effectively distinguishes buildings from trees and characterizes their size, density, orientation, and spacing (see figure); all of these variables are parameters that are required to calculate the estimated surface roughness for a specified area. By using this algorithm, aerodynamic surface roughness values in urban areas can then be extracted automatically. The user can also adjust the algorithm for local conditions and lidar characteristics, like summer/winter vegetation and dense/sparse lidar point spacing. Additionally, the user can also survey variations in surface roughness that occurs due to wind direction; for example, during a hurricane, when wind direction can change dramatically, this variable can be extremely significant. In its current state, the algorithm calculates an estimated surface roughness for a square kilometer area; techniques using the lidar data to calculate the surface roughness for a point, whereby only roughness elements that are upstream from the point of interest are used and the wind direction is a vital concern, are being investigated. This technological advancement will improve the reliability and accuracy of models that use and incorporate surface roughness.

  13. Effect of surface roughness on flexural strength of veneer ceramics.

    PubMed

    Fischer, H; Schäfer, M; Marx, R

    2003-12-01

    The strength of ceramic restorations depends on the occlusal surface roughness of the veneering porcelain, which is influenced by the final preparation. The hypothesis of the study was that roughnesses below a critical microscopic defect size--based only on fracture mechanics considerations--also affect flexural strength. The bending failure stress was evaluated on standard specimens of 4 veneer ceramics with 4 different surfaces of defined roughnesses, respectively. A linear correlation was found between roughness and failure stress. A "roughness-free" failure stress value was predicted for each tested material. This theoretical value can represent the "true" strength of the respective ceramic material. We conclude from our results that the final preparation of a ceramic restoration is critical to the strength of the material, and that ceramic veneering materials can be compared more objectively with respect to their strength by means of roughness-free strength values. PMID:14630897

  14. Effect of surface roughness on the microwave emission from soils

    NASA Technical Reports Server (NTRS)

    Choudhury, B. J.; Schmugge, T. J.; Newton, R. W.; Chang, A. T. C.

    1978-01-01

    The effect of surface roughness on the brightness temperature of a moist terrain was studied through the modification of Fresnel reflection coefficient and using the radiative transfer equation. The modification involves introduction of a single parameter to characterize the roughness. It is shown that this parameter depends on both the surface height variance and the horizontal scale of the roughness. Model calculations are in good quantitative agreement with the observed dependence of the brightness temperature on the moisture content in the surface layer. Data from truck mounted and airborne radiometers are presented for comparison. The results indicate that the roughness effects are greatest for wet soils where the difference between smooth and rough surfaces can be as great as 50K.

  15. Effect of surface roughness on the microwave emission from soils

    NASA Technical Reports Server (NTRS)

    Choudhury, B. J.; Schmugge, T. J.; Chang, A.; Newton, R. W.

    1979-01-01

    The effect of surface roughness on the brightness temperature of a moist terrain has been studied through the modification of Fresnel reflection coefficient and using the radiative transfer equation. The modification involves introduction of a single parameter to characterize the roughness. It is shown that this parameter depends on both the surface height variance and the horizontal scale of the roughness. Model calculations are in good quantitative agreement with the observed dependence of the brightness temperature on the moisture content in the surface layer. Data from truck mounted and airborne radiometers are presented for comparison. The results indicate that the roughness effects are great for wet soils where the difference between smooth and rough surfaces can be as great as 50 K.

  16. Topological Analysis of Rough Surfaces Using Persistent Homology

    NASA Astrophysics Data System (ADS)

    Yamamoto, Ken

    2015-11-01

    This letter investigates rough surfaces using a topological method. The horizontal cross section of a rough surface consists of "islands", and we focus on the topological changes in the island shapes (generation and annihilation of islands and lakes) with changes in elevation. We apply persistent homology to track these topological changes. We numerically confirm that the life spans of the islands and lakes follow power-law distributions, whose scaling exponents vary according to the roughness of the surface. We also provide a theoretical explanation for the relation between these scaling exponents and the roughness exponent with a simple scaling argument. The proposed method successfully connects a topological property with the roughness of a surface.

  17. Optimizing fabrication of electrodeposited 3D surface features

    SciTech Connect

    Steffani, C., LLNL

    1998-07-01

    Selective electrodeposition onto specially masked surfaces (producing blind holes with non-conductive side walls) has been investigated. The thick masks are low cost polymer sheet into which holes and other patterns are machined. Plating with this type of masking system is one method of fabricating medium aspect ratio metallic structures (structures whose width to length ratio is greater than 10/1). The experiment was conducted with deposits of OFC copper from an acid sulfate solution, but similar results are expected with other metals. Structure diameter varied from 0.25 mm to 3.8 mm (0.01`` to 0.150``). The effect of current density, electrolyte concentration, solution temperature, and agitation on deposition rate were investigated. Deposit quality, deposition rate, and optimal plating parameters were evaluated.

  18. Performance assessment of 3D surface imaging technique for medical imaging applications

    NASA Astrophysics Data System (ADS)

    Li, Tuotuo; Geng, Jason; Li, Shidong

    2013-03-01

    Recent development in optical 3D surface imaging technologies provide better ways to digitalize the 3D surface and its motion in real-time. The non-invasive 3D surface imaging approach has great potential for many medical imaging applications, such as motion monitoring of radiotherapy, pre/post evaluation of plastic surgery and dermatology, to name a few. Various commercial 3D surface imaging systems have appeared on the market with different dimension, speed and accuracy. For clinical applications, the accuracy, reproducibility and robustness across the widely heterogeneous skin color, tone, texture, shape properties, and ambient lighting is very crucial. Till now, a systematic approach for evaluating the performance of different 3D surface imaging systems still yet exist. In this paper, we present a systematic performance assessment approach to 3D surface imaging system assessment for medical applications. We use this assessment approach to exam a new real-time surface imaging system we developed, dubbed "Neo3D Camera", for image-guided radiotherapy (IGRT). The assessments include accuracy, field of view, coverage, repeatability, speed and sensitivity to environment, texture and color.

  19. Visualization of 3D elbow kinematics using reconstructed bony surfaces

    NASA Astrophysics Data System (ADS)

    Lalone, Emily A.; McDonald, Colin P.; Ferreira, Louis M.; Peters, Terry M.; King, Graham J. W.; Johnson, James A.

    2010-02-01

    An approach for direct visualization of continuous three-dimensional elbow kinematics using reconstructed surfaces has been developed. Simulation of valgus motion was achieved in five cadaveric specimens using an upper arm simulator. Direct visualization of the motion of the ulna and humerus at the ulnohumeral joint was obtained using a contact based registration technique. Employing fiducial markers, the rendered humerus and ulna were positioned according to the simulated motion. The specific aim of this study was to investigate the effect of radial head arthroplasty on restoring elbow joint stability after radial head excision. The position of the ulna and humerus was visualized for the intact elbow and following radial head excision and replacement. Visualization of the registered humerus/ulna indicated an increase in valgus angulation of the ulna with respect to the humerus after radial head excision. This increase in valgus angulation was restored to that of an elbow with a native radial head following radial head arthroplasty. These findings were consistent with previous studies investigating elbow joint stability following radial head excision and arthroplasty. The current technique was able to visualize a change in ulnar position in a single DoF. Using this approach, the coupled motion of ulna undergoing motion in all 6 degrees-of-freedom can also be visualized.

  20. Theoretical model for the wetting of a rough surface.

    PubMed

    Hay, K M; Dragila, M I; Liburdy, J

    2008-09-15

    Many applications would benefit from an understanding of the physical mechanism behind fluid movement on rough surfaces, including the movement of water or contaminants within an unsaturated rock fracture. Presented is a theoretical investigation of the effect of surface roughness on fluid spreading. It is known that surface roughness enhances the effects of hydrophobic or hydrophilic behavior, as well as allowing for faster spreading of a hydrophilic fluid. A model is presented based on the classification of the regimes of spreading that occur when fluid encounters a rough surface: microscopic precursor film, mesoscopic invasion of roughness and macroscopic reaction to external forces. A theoretical relationship is developed for the physical mechanisms that drive mesoscopic invasion, which is used to guide a discussion of the implications of the theory on spreading conditions. Development of the analytical equation is based on a balance between capillary forces and frictional resistive forces. Chemical heterogeneity is ignored. The effect of various methods for estimating viscous dissipation is compared to available data from fluid rise on roughness experiments. Methods that account more accurately for roughness shape better explain the data as they account for more surface friction; the best fit was found for a hydraulic diameter approximation. The analytical solution implies the existence of a critical contact angle that is a function of roughness geometry, below which fluid will spread and above which fluid will resist spreading. The resulting equation predicts movement of a liquid invasion front with a square root of time dependence, mathematically resembling a diffusive process. PMID:18586259

  1. Study of the effects of surface cladding on 3D transmon

    NASA Astrophysics Data System (ADS)

    Yoscovits, Zachary Robert

    Quantum computing is a very interesting field, due to the ability of quantum computers to solve many problems much faster than a classical computer. Superconducting qubits are electronic circuits composed of superconducting capacitors, inductors and Josephson junctions, which can implement a physical qubit. However they need improvements in their coherence time to create a viable quantum computing. In this work I study the effect on decoherence caused by two level systems in the native oxide that forms on the surface of qubit. To this end I fabricate 3D transmon qubits using materials grown my molecular beam epitaxy, to which a variety of different surface treatments had been applied. I began by fabricating qubits from niobium/aluminum oxide/niobium trilayers. To this end I developed a self-aligned process for fabricating sub-micron Josephson junctions. This process presented many challenges. During the development of this process, it became clear that niobium was an inferior material for fabricating qubits compared to aluminum. I then switched to making qubits from Aluminum. I began by studying the growth of aluminum on sapphire, and was able to achieve aluminum films with an RMS roughness of 0.2 nm by growing on c-plane sapphire that had been annealed in oxygen at 1100 °C and dipped in BOE. Next I fabricated 3D transmon qubits by adapting the standard shadowmask process for use with MBE. I fabricated qubits with a long in situ oxidation to fully passivate the surface before exposure to air. I also passivated the surface by means of growing co deposited aluminum oxide, and by grown aluminum nitride using a nitrogen plasma source. The coherence times of these qubits were compared to those a control sample that had been exposed to air immediately after growth. Overall it doesn't appear that cladding the surface changes the coherence time much, however it is difficult to form conclusions with this small sample size. The coated samples appeared to have slightly

  2. Modeling of surface roughness effects on glaze ice accretion

    NASA Technical Reports Server (NTRS)

    Hansman, R. John, Jr.; Yamaguchi, Keiko; Berkowitz, Brian; Potapczuk, M.

    1989-01-01

    The cause and effects of roughness on accreting glaze ice surfaces were studied with microvideo observations. Distinct zones of surface water behavior were observed, including a smooth wet zone in the stagnation region with a uniform water film, a rough zone where surface tension effects caused coalescence of surface water into stationary beads, and a zone where roughness elements grow into horn shapes. In addition, a zone where surface water ran back as rivulets and a dry zone where rime feathers formed were observed. The locations and behaviors of these zones are discussed. A simple multizone modification to the glaze ice accretion model is proposed to include spatial variability in surface roughness. Two test cases using the multizone model showed significant improvements for the prediction of glaze ice shapes.

  3. Surface roughness reduction using spray-coated hydrogen silsesquioxane reflow

    NASA Astrophysics Data System (ADS)

    Cech, Jiri; Pranov, Henrik; Kofod, Guggi; Matschuk, Maria; Murthy, Swathi; Taboryski, Rafael

    2013-09-01

    Surface roughness or texture is the most visible property of any object, including injection molded plastic parts. Roughness of the injection molding (IM) tool cavity directly affects not only appearance and perception of quality, but often also the function of all manufactured plastic parts. So called “optically smooth” plastic surfaces is one example, where low roughness of a tool cavity is desirable. Such tool surfaces can be very expensive to fabricate using conventional means, such as abrasive diamond polishing or diamond turning. We present a novel process to coat machined metal parts with hydrogen silsesquioxane (HSQ) to reduce their surface roughness. Results from the testing of surfaces made from two starting roughnesses are presented; one polished with grit 2500 sandpaper, another with grit 11.000 diamond polishing paste. We characterize the two surfaces with AFM, SEM and optical profilometry before and after coating. We show that the HSQ coating is able to reduce peak-to-valley roughness more than 20 times on the sandpaper polished sample, from 2.44(±0.99) μm to 104(±22) nm and more than 10 times for the paste polished sample from 1.85(±0.63) μm to 162(±28) nm while roughness averages are reduced 10 and 3 times respectively. We completed more than 10,000 injection molding cycles without detectable degradation of the HSQ coating. This result opens new possibilities for molding of affordable plastic parts with perfect surface finish.

  4. Surface roughness effect on finite oil journal bearings

    NASA Technical Reports Server (NTRS)

    Majumdar, B. C.; Hamrock, B. J.

    1981-01-01

    A theoretical study of the performance of finite oil journal bearings is made, considering the surface roughness effect. The total load supporting ability under such a condition derives from the hydrodynamic as well as asperity contact pressure. These two components of load are calculated separately. The average Reynolds equation for partially lubricated surfaces is used to evaluate hydrodynamic pressure. An analytical expression for average film thickness is obtained and introduced to modify the average Reynolds equation. The resulting differential equation is then solved numerically by finite difference methods for mean hydrodynamic pressure, which in turn gives the hydrodynamic load. Assuming the surface height distribution as Gaussian, the asperity contact pressure is found. The effect of surface roughness parameter, surface pattern, eccentricity ratio, and length to diameter ratio on hydrodynamic load and on side leakage is investigated. It is shown that hydrodynamic load increases with increasing surface roughness when both journal and bearing surfaces have identical roughness structures or when the journal only has a rough surface. The trend of hydrodynamic load is reversed if the journal surface is smooth and the bearing surface is rough.

  5. Holographic microscopy and microfluidics platform for measuring wall stress and 3D flow over surfaces textured by micro-pillars.

    PubMed

    Bocanegra Evans, Humberto; Gorumlu, Serdar; Aksak, Burak; Castillo, Luciano; Sheng, Jian

    2016-01-01

    Understanding how fluid flow interacts with micro-textured surfaces is crucial for a broad range of key biological processes and engineering applications including particle dispersion, pathogenic infections, and drag manipulation by surface topology. We use high-speed digital holographic microscopy (DHM) in combination with a correlation based de-noising algorithm to overcome the optical interference generated by surface roughness and to capture a large number of 3D particle trajectories in a microfluidic channel with one surface patterned with micropillars. It allows us to obtain a 3D ensembled velocity field with an uncertainty of 0.06% and 2D wall shear stress distribution at the resolution of ~65 μPa. Contrary to laminar flow in most microfluidics, we find that the flow is three-dimensional and complex for the textured microchannel. While the micropillars affect the velocity flow field locally, their presence is felt globally in terms of wall shear stresses at the channel walls. These findings imply that micro-scale mixing and wall stress sensing/manipulation can be achieved through hydro-dynamically smooth but topologically rough micropillars. PMID:27353632

  6. Holographic microscopy and microfluidics platform for measuring wall stress and 3D flow over surfaces textured by micro-pillars

    PubMed Central

    Bocanegra Evans, Humberto; Gorumlu, Serdar; Aksak, Burak; Castillo, Luciano; Sheng, Jian

    2016-01-01

    Understanding how fluid flow interacts with micro-textured surfaces is crucial for a broad range of key biological processes and engineering applications including particle dispersion, pathogenic infections, and drag manipulation by surface topology. We use high-speed digital holographic microscopy (DHM) in combination with a correlation based de-noising algorithm to overcome the optical interference generated by surface roughness and to capture a large number of 3D particle trajectories in a microfluidic channel with one surface patterned with micropillars. It allows us to obtain a 3D ensembled velocity field with an uncertainty of 0.06% and 2D wall shear stress distribution at the resolution of ~65 μPa. Contrary to laminar flow in most microfluidics, we find that the flow is three-dimensional and complex for the textured microchannel. While the micropillars affect the velocity flow field locally, their presence is felt globally in terms of wall shear stresses at the channel walls. These findings imply that micro-scale mixing and wall stress sensing/manipulation can be achieved through hydro-dynamically smooth but topologically rough micropillars. PMID:27353632

  7. Holographic microscopy and microfluidics platform for measuring wall stress and 3D flow over surfaces textured by micro-pillars

    NASA Astrophysics Data System (ADS)

    Bocanegra Evans, Humberto; Gorumlu, Serdar; Aksak, Burak; Castillo, Luciano; Sheng, Jian

    2016-06-01

    Understanding how fluid flow interacts with micro-textured surfaces is crucial for a broad range of key biological processes and engineering applications including particle dispersion, pathogenic infections, and drag manipulation by surface topology. We use high-speed digital holographic microscopy (DHM) in combination with a correlation based de-noising algorithm to overcome the optical interference generated by surface roughness and to capture a large number of 3D particle trajectories in a microfluidic channel with one surface patterned with micropillars. It allows us to obtain a 3D ensembled velocity field with an uncertainty of 0.06% and 2D wall shear stress distribution at the resolution of ~65 μPa. Contrary to laminar flow in most microfluidics, we find that the flow is three-dimensional and complex for the textured microchannel. While the micropillars affect the velocity flow field locally, their presence is felt globally in terms of wall shear stresses at the channel walls. These findings imply that micro-scale mixing and wall stress sensing/manipulation can be achieved through hydro-dynamically smooth but topologically rough micropillars.

  8. Quality Analysis of 3d Surface Reconstruction Using Multi-Platform Photogrammetric Systems

    NASA Astrophysics Data System (ADS)

    Lari, Z.; El-Sheimy, N.

    2016-06-01

    In recent years, the necessity of accurate 3D surface reconstruction has been more pronounced for a wide range of mapping, modelling, and monitoring applications. The 3D data for satisfying the needs of these applications can be collected using different digital imaging systems. Among them, photogrammetric systems have recently received considerable attention due to significant improvements in digital imaging sensors, emergence of new mapping platforms, and development of innovative data processing techniques. To date, a variety of techniques haven been proposed for 3D surface reconstruction using imagery collected by multi-platform photogrammetric systems. However, these approaches suffer from the lack of a well-established quality control procedure which evaluates the quality of reconstructed 3D surfaces independent of the utilized reconstruction technique. Hence, this paper aims to introduce a new quality assessment platform for the evaluation of the 3D surface reconstruction using photogrammetric data. This quality control procedure is performed while considering the quality of input data, processing procedures, and photo-realistic 3D surface modelling. The feasibility of the proposed quality control procedure is finally verified by quality assessment of the 3D surface reconstruction using images from different photogrammetric systems.

  9. Wind tunnel model surface gauge for measuring roughness

    NASA Technical Reports Server (NTRS)

    Vorburger, T. V.; Gilsinn, D. E.; Teague, E. C.; Giauque, C. H. W.; Scire, F. E.; Cao, L. X.

    1987-01-01

    The optical inspection of surface roughness research has proceeded along two different lines. First, research into a quantitative understanding of light scattering from metal surfaces and into the appropriate models to describe the surfaces themselves. Second, the development of a practical instrument for the measurement of rms roughness of high performance wind tunnel models with smooth finishes. The research is summarized, with emphasis on the second avenue of research.

  10. Estimating aerodynamic resistance of rough surfaces from angular reflectance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Current wind erosion and dust emission models neglect the heterogeneous nature of surface roughness and its geometric anisotropic effect on aerodynamic resistance, and over-estimate the erodible area by assuming it is not covered by roughness elements. We address these shortfalls with a new model wh...

  11. Fluctuation correlation of the scattered intensity from two-dimensional rough surfaces.

    PubMed

    Zhang, Geng; Wu, Zhensen

    2012-01-16

    The fourth-order moment of the scattered light, namely, the correlation function of the scattered intensity fluctuation from two-dimensional optically weak homogeneous and isotropic rough surfaces obeying Gaussian distribution are investigated based on Beckmann theory and Gaussian moment theorem. Analytical and numerical results are given for the correlation functions of the scattered intensity fluctuation. Also two important special cases, two-frequency correlation and angular correlation, are discussed, as well as the influence of the incident and observation conditions and the characteristic parameters of the rough surfaces on the correlation function which could lead to a more clear understanding of the scattering property of the rough surface and provide a theoretical basis for the 3D target recognition. PMID:22274493

  12. Roughness assessment and wetting behavior of fluorocarbon surfaces.

    PubMed

    Terriza, Antonia; Álvarez, Rafael; Borrás, Ana; Cotrino, José; Yubero, Francisco; González-Elipe, Agustín R

    2012-06-15

    The wetting behavior of fluorocarbon materials has been studied with the aim of assessing the influence of the surface chemical composition and surface roughness on the water advancing and receding contact angles. Diamond like carbon and two fluorocarbon materials with different fluorine content have been prepared by plasma enhanced chemical vapor deposition and characterized by X-ray photoemission, Raman and FT-IR spectroscopies. Very rough surfaces have been obtained by deposition of thin films of these materials on polymer substrates previously subjected to plasma etching to increase their roughness. A direct correlation has been found between roughness and water contact angles while a superhydrophobic behavior (i.e., water contact angles higher than 150° and relatively low adhesion energy) was found for the films with the highest fluorine content deposited on very rough substrates. A critical evaluation of the methods currently used to assess the roughness of these surfaces by atomic force microscopy (AFM) has evidenced that calculated RMS roughness values and actual surface areas are quite dependent on both the scale of observation and image resolution. A critical discussion is carried out about the application of the Wenzel model to account for the wetting behavior of this type of surfaces. PMID:22483335

  13. Surface-to-surface scattering in three-dimensional (3D) topological insulator (TI) thin films

    NASA Astrophysics Data System (ADS)

    Yin, Gen; Wickramaratne, Darshana; Lake, Roger

    2013-03-01

    When the thickness of a 3D TI material is reduced below approximately 6nm, hybridization of the opposite surfaces states can result in inter-surface tunneling. Due to the rotational symmetry of the thin film, the k-s locking relation on opposite surfaces also has opposite chirality. Thus, in this inter-surface scattering mechanism, back-scattering is allowed without the flip of the spin. This effect breaks the protection of TI surface states against back-scattering. To investigate the influence of the inter-surface scattering mechanism, we study different near-elastic scattering mechanisms in the surface state transport using Boltzmann transport equations within the relaxation time approximation. The effect of screened Coulomb impurities, low-energy acoustic phonons and surface magnetic impurities on the TI surface states will be discussed. The response of the inter-surface scattering of TI states to various external stimuli such as a Rashba-like splitting and the orientation of the impurity magnetic moments will also be presented. Using our simulation results, we propose possible experimental methods to modulate the back-scatter protection of TI surface states in thin film TI materials.

  14. Extreme ultraviolet mask substrate surface roughness effects on lithography patterning

    SciTech Connect

    George, Simi; Naulleau, Patrick; Salmassi, Farhad; Mochi, Iacopo; Gullikson, Eric; Goldberg, Kenneth; Anderson, Erik

    2010-06-21

    In extreme ultraviolet lithography exposure systems, mask substrate roughness induced scatter contributes to LER at the image plane. In this paper, the impact of mask substrate roughness on image plane speckle is explicitly evaluated. A programmed roughness mask was used to study the correlation between mask roughness metrics and wafer plane aerial image inspection. We find that the roughness measurements by top surface topography profile do not provide complete information on the scatter related speckle that leads to LER at the image plane. We suggest at wavelength characterization by imaging and/or scatter measurements into different frequencies as an alternative for a more comprehensive metrology of the mask substrate/multilayer roughness effects.

  15. Drop impact upon superhydrophobic surfaces with regular and hierarchical roughness

    NASA Astrophysics Data System (ADS)

    Lv, Cunjing; Hao, Pengfei; Zhang, Xiwen; He, Feng

    2016-04-01

    Recent studies demonstrate that roughness and morphologies of the textures play essential roles on the dynamics of water drop impacting onto superhydrophobic substrates. Particularly, significant reduction of contact time has greatly attracted people's attention. We experimentally investigate drop impact dynamics onto three types of superhydrophobic surfaces, consisting of regular micropillars, two-tier textures with nano/micro-scale roughness, and hierarchical textures with random roughness. It shows that the contact time is controlled by the Weber number and the roughness of the surface. Compared with drop impact on regular micropillared surfaces, the contact time can be finely reduced by increasing the Weber number on surfaces with two-tier textures, but can be remarkably reduced on surfaces with hierarchical textures resulting from the prompt splash and fragmentation of liquid lamellae. Our study may shed lights on textured materials fabrication, allowing a rapid drop detachment to realize broad applications.

  16. Contribution of surface roughness to simulations of historical deforestation

    NASA Astrophysics Data System (ADS)

    Wang, Ye; Wang, Zhaomin

    Surface roughness which partitions surface net radiation into energy fluxes is a key parameter for estimation of biosphere-atmosphere interactions and climate variability. An earth system model of intermediate complexity (EMIC), MPM-2, is used to derive the impact of surface roughness on climate from simulations of historical land cover change effects. The direct change in surface roughness leads to a global surface warming of 0.08 °C through altering the turbulence in the boundary layer. The regional temperature response to surface roughness associated deforestation is very strong at northern mid-latitudes with a most prominent warming of 0.72 °C around 50°N in the Eurasia continent during summer. They can be explained mainly as direct and indirect consequences of decreases in surface albedo and increases in precipitation in response to deforestation, although there are a few significant changes in precipitation. There is also a prominent warming of 0.25 °C around 40°N in the North American continent. This study indicates that land surface roughness plays a significant role which is comparable with the whole land conversion effect in climate change. Therefore, further investigation of roughness-climate relationship is needed to incorporate these aspects.

  17. Modeling of surface roughness effects on glaze ice accretion

    NASA Technical Reports Server (NTRS)

    Hansman, R. John, Jr.; Yamaguchi, Keiko; Berkowitz, Brian M.; Potapczuk, Mark

    1990-01-01

    A series of experimental investigations focused on studying the cause and effect of roughness on accreting glaze ice surfaces were conducted. Detailed microvideo observations were made of glaze ice accretions on 1 to 4 inch diameter cylinders in three icing wind tunnels (the Data Products of New England six inch test facility, the NASA Lewis Icing Research Tunnel, and the B. F. Goodrich Ice Protection Research Facility). Infrared thermal video recordings were made of accreting ice surfaces in the Goodrich facility. Distinct zones of surface water behavior were observed; a smooth wet zone in the stagnation region with a uniform water film; a rough zone where surface tension effects caused coalescence of surface water into stationary beads; a horn zone where roughness elements grow into horn shapes; a runback zone where surface water ran back as rivulets; and a dry zone where rime feathers formed. The location of the transition from the smooth to the rough zone was found to migrate with time towards the stagnation point. The behavior of the transition appeared to be controlled by boundary layer transition and bead formation mechanisms at the interface between the smooth and rough zones. Regions of wet ice growth and enhanced heat transfer were clearly visible in the infrared video recordings of glaze ice surfaces. A simple multi-zone modification to the current glaze ice accretion model was proposed to include spatial variability in surface roughness.

  18. Computer simulation of RBS spectra from samples with surface roughness

    NASA Astrophysics Data System (ADS)

    Malinský, P.; Hnatowicz, V.; Macková, A.

    2016-03-01

    A fast code for the simulation of common RBS spectra including surface roughness effects has been written and tested on virtual samples comprising either a rough layer deposited on a smooth substrate or smooth layer deposited on a rough substrate and simulated at different geometries. The sample surface or interface relief has been described by a polyline and the simulated RBS spectrum has been obtained as the sum of many particular spectra from randomly chosen particle trajectories. The code includes several procedures generating virtual samples with random and regular (periodical) roughness. The shape of the RBS spectra has been found to change strongly with increasing sample roughness and an increasing angle of the incoming ion beam.

  19. Enhancing surface interactions with colon cancer cells on a transferrin-conjugated 3D nanostructured substrate.

    PubMed

    Banerjee, Shashwat S; Paul, Debjani; Bhansali, Sujit G; Aher, Naval D; Jalota-Badhwar, Archana; Khandare, Jayant

    2012-06-11

    A transferrin-conjugated PEG-Fe(3) O(4) nanostructured matrix is developed to explore cellular responses in terms of enhanced cell adhesion, specific interactions between ligands in the matrix and molecular receptors on the cell membrane, comparison of cell shapes on 2D and 3D surfaces, and effect of polymer architecture on cell adhesion. Integration of such advanced synthetic nanomaterials into a functionalized 3D matrix to control cell behavior on surfaces will have implications in nanomedicine. PMID:22434693

  20. Characterisation of the surface structure of 3D printed scaffolds for cell infiltration and surgical suturing.

    PubMed

    Ruiz-Cantu, Laura; Gleadall, Andrew; Faris, Callum; Segal, Joel; Shakesheff, Kevin; Yang, Jing

    2016-03-01

    3D printing is of great interest for tissue engineering scaffolds due to the ability to form complex geometries and control internal structures, including porosity and pore size. The porous structure of scaffolds plays an important role in cell ingrowth and nutrition infusion. Although the internal porosity and pore size of 3D printed scaffolds have been frequently studied, the surface porosity and pore size, which are critical for cell infiltration and mass transport, have not been investigated. The surface geometry can differ considerably from the internal scaffold structure depending on the 3D printing process. It is vital to be able to control the surface geometry of scaffolds as well as the internal structure to fabricate optimal architectures. This work presents a method to control the surface porosity and pore size of 3D printed scaffolds. Six scaffold designs have been printed with surface porosities ranging from 3% to 21%. We have characterised the overall scaffold porosity and surface porosity using optical microscopy and microCT. It has been found that surface porosity has a significant impact on cell infiltration and proliferation. In addition, the porosity of the surface has been found to have an effect on mechanical properties and on the forces required to penetrate the scaffold with a surgical suturing needle. To the authors' knowledge, this study is the first to investigate the surface geometry of extrusion-based 3D printed scaffolds and demonstrates the importance of surface geometry in cell infiltration and clinical manipulation. PMID:26930179

  1. Influence of particle surface roughness on creeping granular motion.

    PubMed

    Sheng, Li-Tsung; Chang, Wei-Ching; Hsiau, Shu-San

    2016-07-01

    A core is formed at the center of a quasi-two-dimensional rotating drum filled more than half with granular material. The core rotates slightly faster than the drum (precession) and decreases in radius over time (erosion) due to the granular creeping motion that occurs below the freely flowing layer. This paper focuses on the effect of the surface roughness of particles on core dynamics, core precession, and core erosion. Two different surface roughness of glass particles having the same diameter were used in the experiments. The surface structures of the particles were quantitatively compared by measuring the coefficients of friction and using a simple image contrast method. The experiments were performed with five different filling levels in a 50-cm-diameter rotating drum. According to the results, core precession and core erosion are both dependent on the particle surface roughness. Core precession becomes weaker and erosion becomes stronger when using particles having a rough surface in the experiments. To explain the physics of core dynamics, the particles' surface roughness effect on the freely flowing layer and the creeping motion region were also investigated. The granular bed velocity field, maximum flowing layer depth δ, shear rate in the flowing layer γ[over ̇], and the creeping region decay constant y_{0} were also calculated in this paper. The effect of the particles' surface roughness on these physical variables well illustrates the physics of core dynamics and creeping granular motion. PMID:27575202

  2. Influence of particle surface roughness on creeping granular motion

    NASA Astrophysics Data System (ADS)

    Sheng, Li-Tsung; Chang, Wei-Ching; Hsiau, Shu-San

    2016-07-01

    A core is formed at the center of a quasi-two-dimensional rotating drum filled more than half with granular material. The core rotates slightly faster than the drum (precession) and decreases in radius over time (erosion) due to the granular creeping motion that occurs below the freely flowing layer. This paper focuses on the effect of the surface roughness of particles on core dynamics, core precession, and core erosion. Two different surface roughness of glass particles having the same diameter were used in the experiments. The surface structures of the particles were quantitatively compared by measuring the coefficients of friction and using a simple image contrast method. The experiments were performed with five different filling levels in a 50-cm-diameter rotating drum. According to the results, core precession and core erosion are both dependent on the particle surface roughness. Core precession becomes weaker and erosion becomes stronger when using particles having a rough surface in the experiments. To explain the physics of core dynamics, the particles' surface roughness effect on the freely flowing layer and the creeping motion region were also investigated. The granular bed velocity field, maximum flowing layer depth δ , shear rate in the flowing layer γ ˙, and the creeping region decay constant y0 were also calculated in this paper. The effect of the particles' surface roughness on these physical variables well illustrates the physics of core dynamics and creeping granular motion.

  3. Counterintuitive MCNPX Results for Scintillator Surface Roughness Effect

    SciTech Connect

    Yuan, Ding; Guss, Paul

    2012-10-01

    We performed a number of comparative MCNPX simulations of gamma energy depositions of scintillation crystals with smooth and rough surfaces. In the study, nine surface patterns (8 micro-roughness + 1 smooth) were coupled with eight common scintillation crystals for a total of 72 possible combinations. Although this was a preliminary study, the outcome was counterintuitive; results generally favored surfaces with micro-roughness over a conventional smooth surface as measured in terms of average energy depositions. The advantage gained through surface roughness is less significant for CdSe and LaCl3, but is most significant for the common NaI and the glass-like SiO2 scintillators. Based on the results of the 64 rough-surface coupled MCNPX simulations, 57 of the 64 (~89%) simulations showed some improvement in energy deposition. The mean improvement in energy deposition was 2.52%. The maximum improvement was about 8.75%, which was achieved when roughening the surface of a SiO2 scintillator using a micro cutting pattern. Further, for a conventional NaI scintillator, MCNPX results suggest that any roughness pattern would improve the energy deposition, with an average improvement of 3.83%. Although the likely causes remain unclear, we intend to focus on presenting simulation results instead of offering a sound explanation of the underlying physics.

  4. Analysis of Surface Roughness at Overlapping Laser Shock Peening

    NASA Astrophysics Data System (ADS)

    Dai, F. Z.; Zhang, Z. D.; Zhou, J. Z.; Lu, J. Z.; Zhang, Y. K.

    2016-02-01

    The overlapping effects on surface roughness are studied when samples are treated by laser shock peening (LSP). Surface roughness of overlapped circular laser spot is calculated by ISO 25178 height parameters. The usually used overlapping styles namely isosceles-right-triangle-style (AAP) and equilateral-triangle-style (AAA) are carefully investigated when the overlapping degree in x-axis (ηx) is below 50%. Surface roughness of isosceles-right-triangle-style attains its minimum value at ηx of 29.3%, and attains its maximum value at ηx of 43.6%. Surface roughness of equilateral-triangle-style attains its minimum value at ηx of 42.3%, and attains its maximum value at ηx of 32%. Experimental results are well consistent with theoretical analysis.

  5. Surface Roughness Measurement on a Wing Aircraft by Speckle Correlation

    PubMed Central

    Salazar, Félix; Barrientos, Alberto

    2013-01-01

    The study of the damage of aeronautical materials is important because it may change the microscopic surface structure profiles. The modification of geometrical surface properties can cause small instabilities and then a displacement of the boundary layer. One of the irregularities we can often find is surface roughness. Due to an increase of roughness and other effects, there may be extra momentum losses in the boundary layer and a modification in the parasite drag. In this paper we present a speckle method for measuring the surface roughness on an actual unmanned aircraft wing. The results show an inhomogeneous roughness distribution on the wing, as expected according to the anisotropic influence of the winds over the entire wing geometry. A calculation of the uncertainty of the technique is given. PMID:24013488

  6. Ice friction: The effects of surface roughness, structure, and hydrophobicity

    NASA Astrophysics Data System (ADS)

    Kietzig, Anne-Marie; Hatzikiriakos, Savvas G.; Englezos, Peter

    2009-07-01

    The effect of surface roughness, structure, and hydrophobicity on ice friction is studied systematically over a wide range of temperature and sliding speeds using several metallic interfaces. Hydrophobicity in combination with controlled roughness at the nanoscale is achieved by femtosecond laser irradiation to mimic the lotus effect on the slider's surface. The controlled roughness significantly increases the coefficient of friction at low sliding speeds and temperatures well below the ice melting point. However, at temperatures close to the melting point and relatively higher speeds, roughness and hydrophobicity significantly decrease ice friction. This decrease in friction is mainly due to the suppression of capillary bridges in spite of the presence of surface asperities that facilitate their formation. Finally, grooves oriented in the sliding direction also significantly decrease friction in the low velocity range compared to scratches and grooves randomly distributed over a surface.

  7. Surface roughness measurement on a wing aircraft by speckle correlation.

    PubMed

    Salazar, Félix; Barrientos, Alberto

    2013-01-01

    The study of the damage of aeronautical materials is important because it may change the microscopic surface structure profiles. The modification of geometrical surface properties can cause small instabilities and then a displacement of the boundary layer. One of the irregularities we can often find is surface roughness. Due to an increase of roughness and other effects, there may be extra momentum losses in the boundary layer and a modification in the parasite drag. In this paper we present a speckle method for measuring the surface roughness on an actual unmanned aircraft wing. The results show an inhomogeneous roughness distribution on the wing, as expected according to the anisotropic influence of the winds over the entire wing geometry. A calculation of the uncertainty of the technique is given. PMID:24013488

  8. Ice friction: The effects of surface roughness, structure, and hydrophobicity

    SciTech Connect

    Kietzig, Anne-Marie; Hatzikiriakos, Savvas G.; Englezos, Peter

    2009-07-15

    The effect of surface roughness, structure, and hydrophobicity on ice friction is studied systematically over a wide range of temperature and sliding speeds using several metallic interfaces. Hydrophobicity in combination with controlled roughness at the nanoscale is achieved by femtosecond laser irradiation to mimic the lotus effect on the slider's surface. The controlled roughness significantly increases the coefficient of friction at low sliding speeds and temperatures well below the ice melting point. However, at temperatures close to the melting point and relatively higher speeds, roughness and hydrophobicity significantly decrease ice friction. This decrease in friction is mainly due to the suppression of capillary bridges in spite of the presence of surface asperities that facilitate their formation. Finally, grooves oriented in the sliding direction also significantly decrease friction in the low velocity range compared to scratches and grooves randomly distributed over a surface.

  9. Equilibrium of wetting layers on rough surfaces

    NASA Astrophysics Data System (ADS)

    Liu, Kuang-Yu

    The objective of this dissertation is to study physical adsorption on solids with complex surface geometry--especially on self-similar and self-affine fractal surfaces--in the context of three phase equilibria. Such studies will facilitate the prediction of the adsorbed film from known surface properties, e.g., topography or interactions (direct problem), and the inference of unknown surface properties from experimental data (inverse problem). These results will then be compared against wetting phenomena on planar surfaces and with other methods of probing complex surface geometries of solids. Chapter One offers the basic context, including wetting phenomena on planar surfaces, the cornerstone prediction of wetting transition on planar surfaces by Cahn, the concepts of fractal geometry, and the formation of fractal objects, for later comparison. The rest of this dissertation will be devoted to the study of multilayer adsorption on fractal surfaces. When a liquid film completely wets the surface, the number of adsorbed molecules as a function of the vapor pressure will depend strongly on the underlying surface geometry. The fractal structure leads to the Frenkel-Halsey-Hill type isotherms with the exponents in the corresponding power laws depending on the fractal dimension and on whether the dominant influence is from the substrate potential (van der Waals wetting) or from the film-vapor surface tension (capillary wetting). The transition between the two is the analog of Cahn's transition: The thermal disorder is replaced by the quenched disorder. This analogy is studied in Chapter Two for self-similar surfaces, and in Chapter Four for self-affine surfaces. In Chapter Two the derivation framework also automatically identifies well-defined coexistence lines in the pressure-dimension diagram. The effect of the repulsive part is examined there too. A simple analysis of adsorption/desorption hysteresis on self-similar surfaces in Chapter Three concludes that the

  10. Real-time 3D surface-image-guided beam setup in radiotherapy of breast cancer

    SciTech Connect

    Djajaputra, David; Li Shidong

    2005-01-01

    We describe an approach for external beam radiotherapy of breast cancer that utilizes the three-dimensional (3D) surface information of the breast. The surface data of the breast are obtained from a 3D optical camera that is rigidly mounted on the ceiling of the treatment vault. This 3D camera utilizes light in the visible range therefore it introduces no ionization radiation to the patient. In addition to the surface topographical information of the treated area, the camera also captures gray-scale information that is overlaid on the 3D surface image. This allows us to visualize the skin markers and automatically determine the isocenter position and the beam angles in the breast tangential fields. The field sizes and shapes of the tangential, supraclavicular, and internal mammary gland fields can all be determined according to the 3D surface image of the target. A least-squares method is first introduced for the tangential-field setup that is useful for compensation of the target shape changes. The entire process of capturing the 3D surface data and subsequent calculation of beam parameters typically requires less than 1 min. Our tests on phantom experiments and patient images have achieved the accuracy of 1 mm in shift and 0.5 deg. in rotation. Importantly, the target shape and position changes in each treatment session can both be corrected through this real-time image-guided system.

  11. A possibility of avoiding surface roughness due to insects

    NASA Technical Reports Server (NTRS)

    Wortmann, F. X.

    1984-01-01

    Discussion of a method for eliminating turbulence caused by the formation of insect roughness upon the leading edges and fuselage, particularly in aircraft using BLC. The proposed technique foresees the use of elastic surfaces on which insect roughness cannot form. The operational characteristics of highly elastic rubber surface fastened to the wing leading edges and fuselage edges are examined. Some preliminary test results are presented. The technique is seen to be advantageous primarily for short-haul operations.

  12. Surface Roughness Parameter Uncertainties on Radar Based Soil Moisture Retrievals

    NASA Technical Reports Server (NTRS)

    Joseph, A. T.; vanderVelde, R.; O'Neill, P. E.; Lang, R.; Su, Z.; Gish, T.

    2012-01-01

    Surface roughness variations are often assumed to be negligible for the retrieval of sol moisture. Although previous investigations have suggested that this assumption is reasonable for natural vegetation covers (i.e. Moran et al. 2002), in-situ measurements over plowed agricultural fields (i.e. Callens et al. 2006) have shown that the soil surface roughness can change considerably due to weathering induced by rain.

  13. Surface roughness scattering of electrons in bulk mosfets

    SciTech Connect

    Zuverink, Amanda Renee

    2015-11-01

    Surface-roughness scattering of electrons at the Si-SiO2 interface is a very important consideration when analyzing Si metal-oxide-semiconductor field-effect transistors (MOSFETs). Scattering reduces the mobility of the electrons and degrades the device performance. 250-nm and 50-nm bulk MOSFETs were simulated with varying device parameters and mesh sizes in order to compare the effects of surface-roughness scattering in multiple devices. The simulation framework includes the ensemble Monte Carlo method used to solve the Boltzmann transport equation coupled with a successive over-relaxation method used to solve the two-dimensional Poisson's equation. Four methods for simulating the surface-roughness scattering of electrons were implemented on both devices and compared: the constant specularity parameter, the momentum-dependent specularity parameter, and the real-space-roughness method with both uniform and varying electric fields. The specularity parameter is the probability of an electron scattering speculariy from a rough surface. It can be chosen as a constant, characterizing partially diffuse scattering of all electrons from the surface the same way, or it can be momentum dependent, where the size of rms roughness and the normal component of the electron wave number determine the probability of electron-momentum randomization. The real-space rough surface method uses the rms roughness height and correlation length of an actual MOSFET to simulate a rough interface. Due to their charge, electrons scatter from the electric field and not directly from the surface. If the electric field is kept uniform, the electrons do not perceive the roughness and scatter as if from a at surface. However, if the field is allowed to vary, the electrons scatter from the varying electric field as they would in a MOSFET. These methods were implemented for both the 50-nm and 250-nm MOSFETs, and using the rms roughness heights and correlation lengths for real devices. The

  14. Noncontact surface roughness measurement using a vision system

    NASA Astrophysics Data System (ADS)

    Koçer, Erdinç; Horozoǧlu, Erhan; Asiltürk, Ilhan

    2015-02-01

    Surface roughness measurement is one of the basic measurement that determines the quality and performance of the final product. After machined operations, tracer end tools are commonly used in industry in order to measure the surface roughness that occurred on the surface. This measurement technique has disadvantages such as user errors because it requires calibration of the device occurring during measurement. In this study, measuring and evaluation techniques were conducted by using display devices over surface image which occurred on the processed surfaces. Surface measurement which performed by getting image makes easier measurement process because it is non-contact, and does not cause any damage. Measurement of surface roughness, and analysis was conducted more precise and accurate. Experimentally obtained results of the measurements on the parts in contact with the device is improved compared with the results of the non-contact image processing software, and satisfactory results were obtained.

  15. ANALYZING SURFACE ROUGHNESS DEPENDENCE OF LINEAR RF LOSSES

    SciTech Connect

    Reece, Charles E.; Kelley, Michael J.; Xu, Chen

    2012-09-01

    Topographic structure on Superconductivity Radio Frequency (SRF) surfaces can contribute additional cavity RF losses describable in terms of surface RF reflectivity and absorption indices of wave scattering theory. At isotropic homogeneous extent, Power Spectrum Density (PSD) of roughness is introduced and quantifies the random surface topographic structure. PSD obtained from different surface treatments of niobium, such Buffered Chemical Polishing (BCP), Electropolishing (EP), Nano-Mechanical Polishing (NMP) and Barrel Centrifugal Polishing (CBP) are compared. A perturbation model is utilized to calculate the additional rough surface RF losses based on PSD statistical analysis. This model will not consider that superconductor becomes normal conducting at fields higher than transition field. One can calculate the RF power dissipation ratio between rough surface and ideal smooth surface within this field range from linear loss mechanisms.

  16. Heat Transfer Variation on Protuberances and Surface Roughness Elements

    NASA Technical Reports Server (NTRS)

    Henry, Robert C.; Hansman, R. John, Jr.; Breuer, Kenneth S.

    1995-01-01

    In order to determine the effect of surface irregularities on local convective heat transfer, the variation in heat transfer coefficients on small (2-6 mm diam) hemispherical roughness elements on a flat plate has been studied in a wind funnel using IR techniques. Heat transfer enhancement was observed to vary over the roughness elements with the maximum heat transfer on the upstream face. This heat transfer enhancement increased strongly with roughness size and velocity when there was a laminar boundary layer on the plate. For a turbulent boundary layer, the heat transfer enhancement was relatively constant with velocity, but did increase with element size. When multiple roughness elements were studied, no influence of adjacent roughness elements on heat transfer was observed if the roughness separation was greater than approximately one roughness element radius. As roughness separation was reduced, less variation in heat transfer was observed on the downstream elements. Implications of the observed roughness enhanced heat transfer on ice accretion modeling are discussed.

  17. Computer-aided surface roughness measurement system

    SciTech Connect

    Hughes, F.J.; Schankula, M.H.

    1983-11-01

    A diamond stylus profilometer with computer-based data acquisition/analysis system is being used to characterize surfaces of reactor components and materials, and to examine the effects of surface topography on thermal contact conductance. The current system is described; measurement problems and system development are discussed in general terms and possible future improvements are outlined.

  18. Comparison of Predicted and Measured Turbine Vane Rough Surface Heat Transfer

    NASA Technical Reports Server (NTRS)

    Boyle, R. J.; Spuckler, C. M.; Lucci, B. L.

    2000-01-01

    The proposed paper compares predicted turbine vane heat transfer for a rough surface over a wide range of test conditions with experimental data. Predictions were made for the entire vane surface. However, measurements were made only over the suction surface of the vane, and the leading edge region of the pressure surface. Comparisons are shown for a wide range of test conditions. Inlet pressures varied between 3 and 15 psia, and exit Mach numbers ranged between 0.3 and 0.9. Thus, while a single roughened vane was used for the tests, the effective rougness,(k(sup +)), varied by more than a factor of ten. Results were obtained for freestream turbulence levels of 1 and 10%. Heat transfer predictions were obtained using the Navier-Stokes computer code RVCQ3D. Two turbulence models, suitable for rough surface analysis, are incorporated in this code. The Cebeci-Chang roughness model is part of the algebraic turbulence model. The k-omega turbulence model accounts for the effect of roughness in the application of the boundary condition. Roughness causes turbulent flow over the vane surface. Even after accounting for transition, surface roughness significantly increased heat transfer compared to a smooth surface. The k-omega results agreed better with the data than the Cebeci-Chang model. However, the low Reynolds number k-omega model did not accurately account for roughness when the freestream turbulence level was low. The high Reynolds number version of this model was more suitable when the freestream turbulence was low.

  19. Characteristics of density currents over regular and irregular rough surfaces

    NASA Astrophysics Data System (ADS)

    Bhaganagar, K.

    2013-12-01

    Direct numerical simulation is used as a tool to understand the effect of surface roughness on the propagation of density currents. Simulations have been performed for lock-exchange flow with gate separating the dense and the lighter fluid. As the lock is released the dense fluid collapses with the lighter fluid on the top, resulting in formation of horizontally evolving density current. The talk will focus on the fundamental differences between the propagation of the density current over regular and irregular rough surfaces. The flow statistics and the flow structures are discussed. The results have revealed the spacing between the roughness elements is an important factor in classifying the density currents. The empirical relations of the front velocity and location for the dense and sparse roughness have been evaluated in terms of the roughness height, spacing between the elements and the initial amount of lock fluid. DNS results for a dense current flowing over a (a) smooth and (b) rough bottom with egg-carton roughness elements in a regular configuration. In these simulations the lock-exchange box is located in the middle of the channel and has two gates which allow two dense currents to be generated, one moving to the right and one to the left side of the channel. Note how the dense current interface presents smaller structures when over a rough bottom (right).

  20. Replicated mask surface roughness effects on EUV lithographic patterning and line edge roughness

    NASA Astrophysics Data System (ADS)

    George, Simi A.; Naulleau, Patrick P.; Gullikson, Eric M.; Mochi, Iacopo; Salmassi, Farhad; Goldberg, Kenneth A.; Anderson, Erik H.

    2011-04-01

    To quantify the roughness contributions to speckle, a programmed roughness substrate was fabricated with a number of areas having different roughness magnitudes. The substrate was then multilayer coated. Atomic force microscopy (AFM) surface maps were collected before and after multilayer deposition. At-wavelength reflectance and total integrated scattering measurements were also completed. Angle resolved scattering based power spectral densities are directly compared to the AFM based power spectra. We show that AFM overpredicts the roughness in the picometer measurements range. The mask was then imaged at-wavelength for the direct characterization of the aerial image speckle using the SEMATECH Berkeley Actinic Inspection Tool (AIT). Modeling was used to test the effectiveness of the different metrologies in predicting the measured aerial-image speckle. AIT measured contrast values are 25% or more than the calculated image contrast values obtained using the measured rms roughness input. The extent to which the various metrologies can be utilized for specifying tolerable roughness limits on EUV masks is still to be determined. Further modeling and measurements are being planned.

  1. Replicated mask surface roughness effects on EUV lithographic pattering and line edge roughness

    SciTech Connect

    George, Simi A.; Naulleau, Patrick P.; Gullikson, Eric M.; Mochi, Iacopo; Salmassi, Farhad; Goldberg, Kenneth A.; Anderson, Erik H.

    2011-03-11

    To quantify the roughness contributions to speckle, a programmed roughness substrate was fabricated with a number of areas having different roughness magnitudes. The substrate was then multilayer coated. Atomic force microscopy (AFM) surface maps were collected before and after multilayer deposition. At-wavelength reflectance and total integrated scattering measurements were also completed. Angle resolved scattering based power spectral densities are directly compared to the AFM based power spectra. We show that AFM overpredicts the roughness in the picometer measurements range. The mask was then imaged at-wavelength for the direct characterization of the aerial image speckle using the SEMATECH Berkeley Actinic Inspection Tool (AIT). Modeling was used to test the effectiveness of the different metrologies in predicting the measured aerial-image speckle. AIT measured contrast values are 25% or more than the calculated image contrast values obtained using the measured rms roughness input. The extent to which the various metrologies can be utilized for specifying tolerable roughness limits on EUV masks is still to be determined. Further modeling and measurements are being planned.

  2. Optical system design of surface roughness photoelectric inspection instrument

    NASA Astrophysics Data System (ADS)

    Xiao, Ze-xin; Li, Peng; Cao, Jie; Xiao, Ran

    2010-11-01

    The light-section method for roughness measurement is one of the most classical measuring methods. According to light-section method which combine visual observation with photomicrography for testing surface roughness, domestic type of 9J is a traditional device. The surface roughness photoelectric inspection instrument which designed by the authors are also based on the theory of light-section, which integrates subjects of optics, mechanical, electronics and calculation. Surface roughness of object image can be obtained on the CCD sensor through the optical system. Using the autonomous software in the computer, the average height of workpiece unevenness Ra value can be measured and read in the monitor. Therefor, surface roughness level can be obtained. In order to design the optical system of device, there are three main aspects which should be finished: 1.Start with requirements of detective object, according to the detective range from Ra12.5 to Ra0.04 ruled by CNS(China National Standards) GB3505-83 the Surface Roughness Term Surface and the Parameters ,parameters on β(magnify power), NA(numerical aperture), WD(work distance), filed of object etc are defined and optimized. Meanwhile, good complementation and compatibility are noticed among three kinds magnification objectives. 2. Special type infinity image distance double telecentricity optical system is constructed. The main point is to design a set of objectives of long WD and infinity image distance flat field semi-apochromat. 3. How to match and optimize the CCD image sensor and lens.

  3. Nanopatterning on rough surfaces using optically trapped microspheres

    NASA Astrophysics Data System (ADS)

    Tsai, Y.-C.; Fardel, R.; Arnold, C. B.

    2011-06-01

    While nanofabricated structures find an increasingly large number of applications, few techniques are able to pattern rough or uneven surfaces, or surfaces with pre-existing structure. In this letter we show that optical trap assisted nanopatterning (OTAN), a near-field laser based technique, is able to produce nanoscale features on surfaces with large roughness but without the need for focus adjustment. Patterning on model surfaces of polyimide with vertical steps greater than 0.5 μm shows a high degree of uniformity, demonstrating that OTAN is a suitable technique to pattern nontraditional surfaces for emerging technologies.

  4. Real-time 3D-surface-guided head refixation useful for fractionated stereotactic radiotherapy

    SciTech Connect

    Li Shidong; Liu Dezhi; Yin Gongjie; Zhuang Ping; Geng, Jason

    2006-02-15

    Accurate and precise head refixation in fractionated stereotactic radiotherapy has been achieved through alignment of real-time 3D-surface images with a reference surface image. The reference surface image is either a 3D optical surface image taken at simulation with the desired treatment position, or a CT/MRI-surface rendering in the treatment plan with corrections for patient motion during CT/MRI scans and partial volume effects. The real-time 3D surface images are rapidly captured by using a 3D video camera mounted on the ceiling of the treatment vault. Any facial expression such as mouth opening that affects surface shape and location can be avoided using a new facial monitoring technique. The image artifacts on the real-time surface can generally be removed by setting a threshold of jumps at the neighboring points while preserving detailed features of the surface of interest. Such a real-time surface image, registered in the treatment machine coordinate system, provides a reliable representation of the patient head position during the treatment. A fast automatic alignment between the real-time surface and the reference surface using a modified iterative-closest-point method leads to an efficient and robust surface-guided target refixation. Experimental and clinical results demonstrate the excellent efficacy of <2 min set-up time, the desired accuracy and precision of <1 mm in isocenter shifts, and <1 deg. in rotation.

  5. Roughness evaluation from ultrapure fluid transfer surface materials for microelectronics fabrication

    NASA Astrophysics Data System (ADS)

    Ulieru, Dumitru G.

    1998-10-01

    The microelectronics fab need the manufacturing in ultraclean environments. The actual and future requirements of new generation of semiconductor devices become more stringent that which demand the reduction of tolerances to particles in cleanroom air and in processing liquids, gases and vacuum. The purity of process chemicals, water and gases is one area under scruting the systems for distribution. These fluids must also be examined so that their contamination charge to be minimal. For examining functional surfaces of fluid distribution systems by using more surface analysis tools such as electron spectroscopy for chemical analysis (ESCA), auger electron spectroscopy for chemical analysis (AES), scanning electron spectroscopy (SEM), brush analyzer or 3D laser scanner provide specification of a material identity, a measure of its surface contaminant, and a measurement record of surface roughness. In our paper we will analyze two case studies of investigation results of surface roughness measurement for electropolished 316L stainless steel and molded polyvinylidene fluoride (PVDF).

  6. Effect of surface morphology on drag and roughness sublayer in flows over regular roughness elements

    NASA Astrophysics Data System (ADS)

    Placidi, Marco; Ganapathisubramani, Bharathram

    2014-11-01

    The effects of systematically varied roughness morphology on bulk drag and on the spatial structure of turbulent boundary layers are examined by performing a series of wind tunnel experiments. In this study, rough surfaces consisting of regularly and uniformly distributed LEGO™ bricks are employed. Twelve different patterns are adopted in order to methodically examine the individual effects of frontal solidity (λF, frontal area of the roughness elements per unit wall-parallel area) and plan solidity (λP, plan area of roughness elements per unit wall-parallel area), on both the bulk drag and the turbulence structure. A floating element friction balance based on Krogstad & Efros (2010) was designed and manufactured to measure the drag generated by the different surfaces. In parallel, high resolution planar and stereoscopic Particle Image Velocimetry (PIV) was applied to investigate the flow features. This talk will focus on the effects of each solidity parameter on the bulk drag and attempt to relate the observed trends to the flow structures in the roughness sublayer. Currently at City University London.

  7. Surface roughness characterization of dental fillings: a diffractive analysis

    NASA Astrophysics Data System (ADS)

    April, Gilbert V.; Bouchard, Michel; Doucet, Michel

    1993-02-01

    The large number of new materials such as amalgams and the variety of techniques for finishing and polishing in operative dentistry has stimulated interest in simple, nondestructive methods of surface roughness evaluation. We studied an optical method based on the scattering of reflected coherent light on prepared samples of composite resins submitted to different surface treatments. The method should be able to measure the degree of flatness of the samples, thus enabling a classification procedure according to a figure of merit to be defined. The diffraction properties of such moderately rough surfaces has been correlated with mechanical profilometer measurements of the residual granular structure after polishing. Different surface treatments of composite resins result in distinctive levels of surface flatness, and it is shown that a relation between the intensity of the normalized specular reflection of a beam of coherent light and the rms surface roughness can be established for characterization purposes.

  8. Interfacial thermodynamics of confined water near molecularly rough surfaces

    PubMed Central

    Mittal, Jeetain; Hummer, Gerhard

    2012-01-01

    We study the effects of nanoscopic roughness on the interfacial free energy of water confined between solid surfaces. SPC/E water is simulated in confinement between two infinite planar surfaces that differ in their physical topology: one is smooth and the other one is physically rough on a nanometer length scale. The two thermodynamic ensembles considered, with constant pressure either normal or parallel to the walls, correspond to different experimental conditions. We find that molecular-scale surface roughness significantly increases the solid-liquid interfacial free energy compared to the smooth surface. For our surfaces with a water-wall interaction energy minimum of −1.2 kcal/mol, we observe a transition from a hydrophilic surface to a hydrophobic surface at a roughness amplitude of about 3 Å and a wave length of 11.6 Å, with the interfacial free energy changing sign from negative to positive. In agreement with previous studies of water near hydrophobic surfaces, we find an increase in the isothermal compressibility of water with increasing surface roughness. Interestingly, average measures of the water density and hydrogen-bond number do not contain distinct signatures of increased hydrophobicity. In contrast, a local analysis indicates transient dewetting of water in the valleys of the rough surface, together with a significant loss of hydrogen bonds, and a change in the dipole orientation toward the surface. These microscopic changes in the density, hydrogen bonding, and water orientation contribute to the large increase in the interfacial free energy, and the change from a hydrophilic to a hydrophobic character of the surface. PMID:21043431

  9. Effect of surface roughness on characteristics of spherical shock waves

    NASA Technical Reports Server (NTRS)

    Huber, Paul W; Mcfarland, Donald R

    1955-01-01

    An investigation has been conducted on a small-scale test layout in which direct observation of the shock wave movement with time could be made in order to determine the effects of surface roughness on the characteristics of spherical shock waves. Data were obtained with 15-gram pentolite charges at four heights of burst, both for a smooth surface and for a surface completely covered with pyramid-shaped roughness elements. The observations resulted in determinations of shock peak overpressure and Mach stem height as a function of distance for each test. Comparison of the smooth-surface data with those obtained for the extremely rough condition showed a small net effort of roughness on the shock peak overpressures at the surface for all burst heights, the effect being to lower the overpressures. The effect of surface roughness on the Mach stem formation and growth was to delay the formation at the greatest charge height and to lower the height of the Mach stem for all heights.Comparison of the free-air shock peak overpressures with larger scale data showed good similarity of the overpressure-distance relationships. The data did not fit a geometrical similarity parameter for the path of the triple point at different heights of burst suggested by other investigators. A simple similarity parameter (relating the horizontal distance to the theoretical point of Mach formation) was found which showed only a small influence of burst height on the path of the triple point. While the data presented provide knowledge of the effect of many surface-roughness elements on the overall shock characteristics, the data do not provide insight into the details of the air-flow characteristics along the surface, nor the relative contribution of individual roughness elements to the results obtained.

  10. Roughness and waviness requirements for laminar flow surfaces

    NASA Technical Reports Server (NTRS)

    Obara, Clifford J.; Holmes, Bruce J.

    1986-01-01

    Many modern metal and composite airframe manufacturing techniques can provide surface smoothness which is compatible with natural laminar flow (NLF) requirements. An important consideration is manufacturing roughness of the surface in the form of steps and gaps perpendicular to the freestream. The principal challenge to the design and manufacture of laminar flow surfaces today appears to be in the installation of leading-edge panels on wing, nacelle, and empennage surfaces. A similar challenge is in the installation of access panels, doors, windows, fuselage noses, and engine nacelles. Past work on roughness and waviness manufacturing tolerances and comparisons with more recent experiments are reviewed.

  11. Fish body surface data measurement based on 3D digital image correlation

    NASA Astrophysics Data System (ADS)

    Jiang, Ming; Qian, Chen; Yang, Wenkai

    2016-01-01

    To film the moving fish in the glass tank, light will be bent at the interface of air and glass, glass and water. Based on binocular stereo vision and refraction principle, we establish a mathematical model of 3D image correlation to reconstruct the 3D coordinates of samples in the water. Marking speckle in fish surface, a series of real-time speckle images of swimming fish will be obtained by two high-speed cameras, and instantaneous 3D shape, strain, displacement etc. of fish will be reconstructed.

  12. Surface Roughness and Snow Accumulation in East Antarctica

    NASA Astrophysics Data System (ADS)

    Scambos, T. A.; Vornberger, P. L.; Bohlander, J. A.; Das, I.; Klinger, M.; Pope, A.; Lenaerts, J.; Fahnestock, M. A.

    2015-12-01

    A complex relationship exists between snow accumulation (e.g., net surface mass balance) and meter-scale surface roughness as represented by sastrugi and erosional structures over the East Antarctic Ice Sheet (EAIS). The morphology of the ice sheet at this scale is a result of a complex interaction between katabatic winds, synoptic storms, and the slope of the surface, all driving local patterns of snow accretion and sublimation. In megadune regions, the accumulation, surface slope, and surface roughness are highly correlated with slope. Smooth glazed surfaces are present on the steeper leeward wind-faces, and much rougher snow-accreting megadunes are present on the windward (depositional) slope. However, the highest elevation areas near the ridge crest of the EAIS (above ~3200 m) have a converse relationship between roughness and accumulation. Here, very low wind ridge crest areas are smooth and have higher accumulation than adjacent, slightly steeper regions that exhibit a slight increase in roughness. Below the main regions of megadunes (<~2000 m) wind glaze areas gradually become rougher as wind scouring and erosion dominate locally steeper regions. In coastal areas (<~1000), roughness is highly variable, and is tied to frequent synoptic storm deposition. We compare roughness data derived from MISR (Multi-angle Imaging SpectroRadiometer) and Landsat 8 acquisitions with available wind and accumulation data from climate model results and field measurements. Roughness is determined by sunlight scattering relative to viewing geometry (MISR) or from the amplitude of textural characteristics tied to surface sastrugi (Landsat 8). Both are validated by comparison with meter-scale images (WorldView-1) and field observations. MISR roughness mapping shows persistent qualitative patterns of surface roughness across the EAIS, but an absolute roughness scale mapping is difficult to generate because of complex viewing, illumination, and bi-directional reflectance variations

  13. Finite element modeling of the surface roughness of 5052 Al alloy subjected to a surface severe plastic deformation process

    SciTech Connect

    Dai, K.; Villegas, J.; Stone, Z.; Shaw, L. . E-mail: lshaw@mail.ims.uconn.edu

    2004-12-01

    The surface of 5052 Al alloy plates is severely plastically deformed via multiple impacts by high-velocity tungsten carbide/cobalt (Wc/Co) balls in a surface nanocrystallization and hardening (SNH) process. The surface roughness of 5052 Al alloy plates as a function of the impacting ball size and processing time has been evaluated via non-contact 3D profilometry. A three-dimensional finite element (FE) model has been developed to simulate the formation of peaks and valleys during the SNH process. The peak-to-valley distance predicted from the FEM matches the maximum PV value measured experimentally quite well, indicating that surface roughening of 5052 Al alloy plates during the SNH process using WC/Co balls is mainly dictated by the indentation process of the impacting balls. The implications of this surface roughening mechanism in the final surface roughness, processing time, related microstructure change, and property alteration are discussed.

  14. X-ray reflectivity and surface roughness

    SciTech Connect

    Ocko, B.M.

    1988-01-01

    Since the advent of high brightness synchrotron radiation sources there has been a phenomenal growth in the use of x-rays as a probe of surface structure. The technique of x-ray reflectivity is particularly relevant to electrochemists since it is capable of probing the structure normal to an electrode surface in situ. In this paper the theoretical framework for x-ray reflectivity is reviewed and the results from previous non-electrochemistry measurements are summarized. These measurements are from the liquid/air interface (CCl/sub 4/), the metal crystal vacuum interface (Au(100)), and from the liquid/solid interface(liquid crystal/silicon). 34 refs., 5 figs.

  15. Simplified generation of biomedical 3D surface model data for embedding into 3D portable document format (PDF) files for publication and education.

    PubMed

    Newe, Axel; Ganslandt, Thomas

    2013-01-01

    The usefulness of the 3D Portable Document Format (PDF) for clinical, educational, and research purposes has recently been shown. However, the lack of a simple tool for converting biomedical data into the model data in the necessary Universal 3D (U3D) file format is a drawback for the broad acceptance of this new technology. A new module for the image processing and rapid prototyping framework MeVisLab does not only provide a platform-independent possibility to create surface meshes out of biomedical/DICOM and other data and to export them into U3D--it also lets the user add meta data to these meshes to predefine colors and names that can be processed by a PDF authoring software while generating 3D PDF files. Furthermore, the source code of the respective module is available and well documented so that it can easily be modified for own purposes. PMID:24260144

  16. Simplified Generation of Biomedical 3D Surface Model Data for Embedding into 3D Portable Document Format (PDF) Files for Publication and Education

    PubMed Central

    Newe, Axel; Ganslandt, Thomas

    2013-01-01

    The usefulness of the 3D Portable Document Format (PDF) for clinical, educational, and research purposes has recently been shown. However, the lack of a simple tool for converting biomedical data into the model data in the necessary Universal 3D (U3D) file format is a drawback for the broad acceptance of this new technology. A new module for the image processing and rapid prototyping framework MeVisLab does not only provide a platform-independent possibility to create surface meshes out of biomedical/DICOM and other data and to export them into U3D – it also lets the user add meta data to these meshes to predefine colors and names that can be processed by a PDF authoring software while generating 3D PDF files. Furthermore, the source code of the respective module is available and well documented so that it can easily be modified for own purposes. PMID:24260144

  17. Interaction of fast charges with a rough metal surface

    NASA Astrophysics Data System (ADS)

    Lyon, Keenan; Zhang, Ying-Ying; Mišković, Z. L.; Song, Yuan-Hong; Wang, You-Nian

    2015-09-01

    We use the Green function formulation of a dielectric response formalism to study the dynamic polarization of a rough metal surface by a single charged particle and by a pair of charged particles that move parallel to the surface. While the surface roughness is treated nonperturbatively, the plasmon excitation of the metal electron gas is described locally. We find that the magnitudes of both the image potential and the stopping power of a single particle are increased by the increasing roughness and decreasing correlation length of the surface. On the other hand, both the long-range wake potential of a single charged particle and the interaction potential between two particles are weakly affected by the surface roughness. However, the strongest effects of the surface roughness are seen in the correlated stopping power of two charged particles, giving rise to oscillations in the dependence of the stopping ratio on their distance, both when the interparticle axis is perpendicular to their direction of motion and when the wake-related oscillations are damped by adiabatic suppression of plasmon excitations at low particle speeds.

  18. Correlation between frictional force and surface roughness of orthodontic archwires.

    PubMed

    Choi, Samjin; Hwang, Eun-Young; Park, Hun-Kuk; Park, Young-Guk

    2015-01-01

    Lateral force microscopy measures the lateral bending of the cantilever depending on the frictional force acting between the tip and surface. The aim of this study was to investigate and compare the relationship between the surface roughness and frictional resistance of four archwire and bracket combinations consisting of the 0.016-inch NiTi and 0.019 × 0.025-inch stainless steel archwires interacting clinically with two representative self-ligating brackets, active-type Clippy-C(®) ceramic self-ligating brackets, and passive-type Damon(®) stainless steel self-ligating brackets, using the lateral force microscopy technique. A 0.016-inch NiTi archwire interacting with passive-type Damon(®) stainless steel self-ligating brackets showed the smoothest surface roughness and the lowest frictional resistance compared to other combinations. The archwires interacting with passive-type Damon(®) stainless steel self-ligating brackets showed significantly lower surface roughness and frictional resistance than those interacting with active-type Clippy-C(®) ceramic self-ligating brackets. The frictional force in the in vivo archwire and bracket system increased with increasing surface roughness of the archwire. This positive correlation suggests that surface roughness can be used as an evaluating marker for estimating the efficiency of orthodontic treatment, rather than the direct measurement of frictional force. PMID:26018223

  19. Structural contribution to the roughness of supersmooth crystal surface

    SciTech Connect

    Butashin, A. V.; Muslimov, A. E. Kanevsky, V. M.; Deryabin, A. N.; Pavlov, V. A.; Asadchikov, V. E.

    2013-05-15

    Technological advances in processing crystals (Si, sapphire {alpha}-Al{sub 2}O{sub 3}, SiC, GaN, LiNbO{sub 3}, SrTiO{sub 3}, etc.) of substrate materials and X-ray optics elements make it possible to obtain supersmooth surfaces with a periodicity characteristic of the crystal structure. These periodic structures are formed by atomically smooth terraces and steps of nano- and subnanometer sizes, respectively. A model surface with such nanostructures is proposed, and the relations between its roughness parameters and the height of atomic steps are determined. The roughness parameters calculated from these relations almost coincide with the experimental atomic force microscopy (AFM) data obtained from 1 Multiplication-Sign 1 and 10 Multiplication-Sign 10 {mu}m areas on the surface of sapphire plates with steps. The minimum roughness parameters for vicinal crystal surfaces, which are due to the structural contribution, are calculated based on the approach proposed. A comparative analysis of the relief and roughness parameters of sapphire plate surfaces with different degrees of polishing is performed. A size effect is established: the relief height distribution changes from stochastic to regular with a decrease in the surface roughness.

  20. Electromagnetic scattering and depolarization across rough surfaces: Full wave analysis

    NASA Astrophysics Data System (ADS)

    Bahar, Ezekiel; Huang, Guorong; Lee, Bom Son

    1995-05-01

    Full wave solutions are derived for vertically and horizontally polarized waves diffusely scattered across an interface that is two-dimensionally rough separating two different propagating media. Since the normal to the rough surface is not restricted to the reference plane of incidence, the waves are depolarized upon scattering; and the single scattered radiation fields are expressed as integrals of a surface element transmission scattering matrix that also accounts for coupling between the vertically and horizontally polarized waves. The integrations are over the rough surface area as well as the complete two-dimensional wave spectra of the radiation fields. The full wave solutions satisfy the duality and reciprocity relationships in electromagnetic theory, and the surface element scattering matrix is invariant to coordinate transformations. It is shown that in the high-frequency limit the full wave solutions reduce to the physical optics solutions, while in the low-frequency limit (for small mean square heights and slopes) the full wave solutions reduce to Rice's (1951) small perturbation solutions. Thus, the full wave solution accounts for specular point scattering as well as diffuse, Bragg-type scattering in a unified, self-consistent manner. It is therefore not necessary to use hybrid, perturbation and physical optics approaches (based on two-scale models of composite surfaces with large and small roughness scales) to determine the like- and cross-polarized fields scattered across the rough surface.

  1. Land surface temperature from INSAT-3D imager data: Retrieval and assimilation in NWP model

    NASA Astrophysics Data System (ADS)

    Singh, Randhir; Singh, Charu; Ojha, Satya P.; Kumar, A. Senthil; Kishtawal, C. M.; Kumar, A. S. Kiran

    2016-06-01

    A new algorithm is developed for retrieving the land surface temperature (LST) from the imager radiance observations on board geostationary operational Indian National Satellite (INSAT-3D). The algorithm is developed using the two thermal infrared channels (TIR1 10.3-11.3 µm and TIR2 11.5-12.5 µm) via genetic algorithm (GA). The transfer function that relates LST and thermal radiances is developed using radiative transfer model simulated database. The developed algorithm has been applied on the INSAT-3D observed radiances, and LST retrieved from the developed algorithm has been validated with Moderate Resolution Imaging Spectroradiometer land surface temperature (LST) product. The developed algorithm demonstrates a good accuracy, without significant bias and standard deviations of 1.78 K and 1.41 K during daytime and nighttime, respectively. The newly proposed algorithm performs better than the operational algorithm used for LST retrieval from INSAT-3D satellite. Further, a set of data assimilation experiments is conducted with the Weather Research and Forecasting (WRF) model to assess the impact of INSAT-3D LST on model forecast skill over the Indian region. The assimilation experiments demonstrated a positive impact of the assimilated INSAT-3D LST, particularly on the lower tropospheric temperature and moisture forecasts. The temperature and moisture forecast errors are reduced (as large as 8-10%) with the assimilation of INSAT-3D LST, when compared to forecasts that were obtained without the assimilation of INSAT-3D LST. Results of the additional experiments of comparative performance of two LST products, retrieved from operational and newly proposed algorithms, indicate that the impact of INSAT-3D LST retrieved using newly proposed algorithm is significantly larger compared to the impact of INSAT-3D LST retrieved using operational algorithm.

  2. Clinical evaluation of accommodation and ocular surface stability relavant to visual asthenopia with 3D displays

    PubMed Central

    2014-01-01

    Background To validate the association between accommodation and visual asthenopia by measuring objective accommodative amplitude with the Optical Quality Analysis System (OQAS®, Visiometrics, Terrassa, Spain), and to investigate associations among accommodation, ocular surface instability, and visual asthenopia while viewing 3D displays. Methods Fifteen normal adults without any ocular disease or surgical history watched the same 3D and 2D displays for 30 minutes. Accommodative ability, ocular protection index (OPI), and total ocular symptom scores were evaluated before and after viewing the 3D and 2D displays. Accommodative ability was evaluated by the near point of accommodation (NPA) and OQAS to ensure reliability. The OPI was calculated by dividing the tear breakup time (TBUT) by the interblink interval (IBI). The changes in accommodative ability, OPI, and total ocular symptom scores after viewing 3D and 2D displays were evaluated. Results Accommodative ability evaluated by NPA and OQAS, OPI, and total ocular symptom scores changed significantly after 3D viewing (p = 0.005, 0.003, 0.006, and 0.003, respectively), but yielded no difference after 2D viewing. The objective measurement by OQAS verified the decrease of accommodative ability while viewing 3D displays. The change of NPA, OPI, and total ocular symptom scores after 3D viewing had a significant correlation (p < 0.05), implying direct associations among these factors. Conclusions The decrease of accommodative ability after 3D viewing was validated by both subjective and objective methods in our study. Further, the deterioration of accommodative ability and ocular surface stability may be causative factors of visual asthenopia in individuals viewing 3D displays. PMID:24612686

  3. 3D surface reconstruction based on image stitching from gastric endoscopic video sequence

    NASA Astrophysics Data System (ADS)

    Duan, Mengyao; Xu, Rong; Ohya, Jun

    2013-09-01

    This paper proposes a method for reconstructing 3D detailed structures of internal organs such as gastric wall from endoscopic video sequences. The proposed method consists of the four major steps: Feature-point-based 3D reconstruction, 3D point cloud stitching, dense point cloud creation and Poisson surface reconstruction. Before the first step, we partition one video sequence into groups, where each group consists of two successive frames (image pairs), and each pair in each group contains one overlapping part, which is used as a stitching region. Fist, the 3D point cloud of each group is reconstructed by utilizing structure from motion (SFM). Secondly, a scheme based on SIFT features registers and stitches the obtained 3D point clouds, by estimating the transformation matrix of the overlapping part between different groups with high accuracy and efficiency. Thirdly, we select the most robust SIFT feature points as the seed points, and then obtain the dense point cloud from sparse point cloud via a depth testing method presented by Furukawa. Finally, by utilizing Poisson surface reconstruction, polygonal patches for the internal organs are obtained. Experimental results demonstrate that the proposed method achieves a high accuracy and efficiency for 3D reconstruction of gastric surface from an endoscopic video sequence.

  4. Depolarization of Light Scattered from Rough Cylindrical Surfaces

    NASA Astrophysics Data System (ADS)

    Aparicio, R.; Quintián, F. Perez; Rebollo, M. A.

    2008-04-01

    In this work we study the state of polarization of light scattered from rough cylindrical surfaces. The experimental results show that the amount of cross-polarized light at a particular observation angle is correlated with the roughness of the cylinders. We compare these results with those obtained using the Kirchhoff's vector theory and analyze if the differences can be modeled on multiple-scattering effects.

  5. Constructing topologically connected surfaces for the comprehensive analysis of 3-D medical structures

    NASA Astrophysics Data System (ADS)

    Kalvin, Alan D.; Cutting, Court B.; Haddad, Betsy; Noz, Marilyn E.

    1991-06-01

    Three-dimensional (3D) medical imaging deals with the visualization, manipulation, and measuring of objects in 3D medical images. So far, research efforts have concentrated primarily on visualization, using well-developed methods from computer graphics. Very little has been achieved in developing techniques for manipulating medical objects, or for extracting quantitative measurements from them beyond volume calculation (by counting voxels), and computing distances and angles between manually located surface points. A major reason for the slow pace in the development of manipulation and quantification methods lies with the limitations of current algorithms for constructing surfaces from 3D solid objects. We show that current surface construction algorithms either (a) do not construct valid surface descriptions of solid objects or (b) produce surface representations that are not particularly suitable for anything other than visualization. We present ALLIGATOR, a new surface construction algorithm that produces valid, topologically connected surface representations of solid objects. We have developed a modeling system based on the surface representations created by ALLIGATOR that is suitable for developing algorithms to visualize, manipulate, and quantify 3D medical objects. Using this modeling system we have developed a method for efficiently computing principle curvatures and directions on surfaces. These measurements form the basis for a new metric system being developed for morphometrics. The modeling system is also being used in the development of systems for quantitative pre-surgical planning and surgical augmentation.

  6. Automated generation of NC part programs for excimer laser ablation micromachining from known 3D surfaces

    NASA Astrophysics Data System (ADS)

    Mutapcic, Emir; Iovenitti, Pio G.; Hayes, Jason P.

    2002-11-01

    The purpose of this research project is to improve the capability of the laser micromachinning process, so that any desired 3D surface can be produced by taking the 3D information from a CAD system and automatically generating the NC part programs. In addition, surface quality should be able to be controlled by specifying optimised parameters. This paper presents the algorithms and a software system, which processes 3D geometry in an STL file format from a CAD system and produces the NC part program to mill the surface using the Excimer laser ablation process. Simple structures are used to demonstrate the prototype system's part programming capabilities, and an actual surface is machined.

  7. Exact surface registration of retinal surfaces from 3-D optical coherence tomography images.

    PubMed

    Lee, Sieun; Lebed, Evgeniy; Sarunic, Marinko V; Beg, Mirza Faisal

    2015-02-01

    Nonrigid registration of optical coherence tomography (OCT) images is an important problem in studying eye diseases, evaluating the effect of pharmaceuticals in treating vision loss, and performing group-wise cross-sectional analysis. High dimensional nonrigid registration algorithms required for cross-sectional and longitudinal analysis are still being developed for accurate registration of OCT image volumes, with the speckle noise in images presenting a challenge for registration. Development of algorithms for segmentation of OCT images to generate surface models of retinal layers has advanced considerably and several algorithms are now available that can segment retinal OCT images into constituent retinal surfaces. Important morphometric measurements can be extracted if accurate surface registration algorithm for registering retinal surfaces onto corresponding template surfaces were available. In this paper, we present a novel method to perform multiple and simultaneous retinal surface registration, targeted to registering surfaces extracted from ocular volumetric OCT images. This enables a point-to-point correspondence (homology) between template and subject surfaces, allowing for a direct, vertex-wise comparison of morphometric measurements across subject groups. We demonstrate that this approach can be used to localize and analyze regional changes in choroidal and nerve fiber layer thickness among healthy and glaucomatous subjects, allowing for cross-sectional population wise analysis. We also demonstrate the method's ability to track longitudinal changes in optic nerve head morphometry, allowing for within-individual tracking of morphometric changes. This method can also, in the future, be used as a precursor to 3-D OCT image registration to better initialize nonrigid image registration algorithms closer to the desired solution. PMID:25312906

  8. Poly(acrylic acid) brushes pattern as a 3D functional biosensor surface for microchips

    NASA Astrophysics Data System (ADS)

    Wang, Yan-Mei; Cui, Yi; Cheng, Zhi-Qiang; Song, Lu-Sheng; Wang, Zhi-You; Han, Bao-Hang; Zhu, Jin-Song

    2013-02-01

    Poly(acrylic acid) (PAA) brushes, a novel three dimensional (3D) precursor layer of biosensor or protein microarrays, possess high protein loading level and low non-specific protein adsorption. In this article, we describe a simple and convenient way to fabricate 3D PAA brushes pattern by microcontact printing (μCP) and characterize it with FT-IR and optical microscopy. The carboxyl groups of PAA brushes can be applied to covalently immobilize protein for immunoassay. Thriving 3D space made by patterning PAA brushes thin film is available to enhance protein immobilization, which is confirmed by measuring model protein interaction between human immunoglobulin G (H-IgG) and goat anti-H-IgG (G-H-IgG) with fluorescence microscopy and surface plasmon resonance imaging (SPRi). As expected, the SPRi signals of H-IgG coating on 3D PAA brushes pattern and further measuring specific binding with G-H-IgG are all larger than that of 3D PAA brushes without pattern and 2D bare gold surface. We further revealed that this surface can be used for high-throughput screening and clinical diagnosis by label-free assaying of Hepatitis-B-Virus surface antibody (HBsAb) with Hepatitis-B-Virus surface antigen (HBsAg) concentration array chip. The linearity range for HBsAb assay is wider than that of conventional ELISA method.

  9. Thermal slip for liquids at rough solid surfaces

    NASA Astrophysics Data System (ADS)

    Zhang, Chengbin; Chen, Yongping; Peterson, G. P.

    2014-06-01

    Molecular dynamics simulation is used to examine the thermal slip of liquids at rough solid surfaces as characterized by fractal Cantor structures. The temperature profiles, potential energy distributions, thermal slip, and interfacial thermal resistance are investigated and evaluated for a variety of surface topographies. In addition, the effects of liquid-solid interaction, surface stiffness, and boundary condition on thermal slip length are presented. Our results indicate that the presence of roughness expands the low potential energy regions in adjacent liquids, enhances the energy transfer at liquid-solid interface, and decreases the thermal slip. Interestingly, the thermal slip length and thermal resistance for liquids in contact with solid surfaces depends not only on the statistical roughness height, but also on the fractal dimension (i.e., topographical spectrum).

  10. Ghost imaging for a reflected object with a rough surface

    SciTech Connect

    Wang Chunfang; Zhang Dawei; Chen Bin; Bai Yanfeng

    2010-12-15

    Ghost imaging for the reflected object with rough surface is investigated. The surface height variance {sigma}{sub h}{sup 2} and the correlation length l{sub c} have been introduced to characterize the rough surface. Based on a simple scattering model, we derive the analytical expressions which are used to describe the effects of {sigma}{sub h}{sup 2} and l{sub c} on ghost imaging. The results show that both {sigma}{sub h}{sup 2} and l{sub c} have no influence on the image resolution, while the convergence of the correlation decreases as {sigma}{sub h}{sup 2} increases. Additionally, the bucket detector used in the test arm can dramatically improve the visibility of ghost images. The results are backed up by numerical simulations, in which a Monte Carlo approach to generate a rough surface has been used.

  11. Response Ant Colony Optimization of end milling surface roughness.

    PubMed

    Kadirgama, K; Noor, M M; Abd Alla, Ahmed N

    2010-01-01

    Metal cutting processes are important due to increased consumer demands for quality metal cutting related products (more precise tolerances and better product surface roughness) that has driven the metal cutting industry to continuously improve quality control of metal cutting processes. This paper presents optimum surface roughness by using milling mould aluminium alloys (AA6061-T6) with Response Ant Colony Optimization (RACO). The approach is based on Response Surface Method (RSM) and Ant Colony Optimization (ACO). The main objectives to find the optimized parameters and the most dominant variables (cutting speed, feedrate, axial depth and radial depth). The first order model indicates that the feedrate is the most significant factor affecting surface roughness. PMID:22294914

  12. Response Ant Colony Optimization of End Milling Surface Roughness

    PubMed Central

    Kadirgama, K.; Noor, M. M.; Abd Alla, Ahmed N.

    2010-01-01

    Metal cutting processes are important due to increased consumer demands for quality metal cutting related products (more precise tolerances and better product surface roughness) that has driven the metal cutting industry to continuously improve quality control of metal cutting processes. This paper presents optimum surface roughness by using milling mould aluminium alloys (AA6061-T6) with Response Ant Colony Optimization (RACO). The approach is based on Response Surface Method (RSM) and Ant Colony Optimization (ACO). The main objectives to find the optimized parameters and the most dominant variables (cutting speed, feedrate, axial depth and radial depth). The first order model indicates that the feedrate is the most significant factor affecting surface roughness. PMID:22294914

  13. Analysis of surface roughness generation in aircraft ice accretion

    NASA Technical Reports Server (NTRS)

    Hansman, R. J., Jr.; Reehorst, Andrew; Sims, James

    1992-01-01

    Patterns of roughness evolution have been studied analysis of high magnification video observations of accreting ice surfaces provided by the NASA Lewis Research Center. Three distinct patterns of surface roughness generation have been identified within the parametric regions studied. They include: Rime, Multi-Zone Glaze, and Uniform Glaze. Under most icing conditions, a brief period of transient rime ice growth was observed caused by heat conduction into the body. The resulting thin rime layer explains previously observed insensitivity of some ice accretions to substrate insensitivity of some ice accretions to substrate surface chemistry and may provide justification for simplifying assumptions in ice accretion sailing and modeling effects.

  14. Surface roughness effects with solid lubricants dispersed in mineral oils

    NASA Technical Reports Server (NTRS)

    Cusano, C.; Goglia, P. R.; Sliney, H. E.

    1983-01-01

    The lubricating effectiveness of solid-lubricant dispersions are investigated in both point and line contacts using surfaces with both random and directional roughness characteristics. Friction and wear data obtained at relatively low speeds and at room temperature, indicate that the existence of solid lubricants such as graphite, MoS2, and PTFE in a plain mineral oil generally will not improve the effectiveness of the oil as a lubricant for such surfaces. Under boundary lubrication conditions, the friction force, as a function of time, initially depends upon the directional roughness properties of the contacting surfaces irrespective of whether the base oil or dispersions are used as lubricants.

  15. Full Wave Single and Double Scatter from Rough Surfaces

    NASA Astrophysics Data System (ADS)

    Bahar, E.; El-Shenawee, M.

    1994-12-01

    Using the full wave approach, the single and double scattered electromagnetic fields from deterministic one-dimensional rough surfaces are computed. Full wave expressions for the single and double scattered far fields are given in terms of multidimensional integrals. These integrals are evaluated using the Cornell National Supercomputer IBM/3090. Applying the steepest descent approximation to the double scattered field expressions, the dimensions of the integrals are reduced from four to two in the case of one-dimensional rough surfaces. It is shown that double scatter in the backward direction is significant for near normal incidence when the rough surface is highly conducting and its mean square slope is very large. Even for one-dimensional rough surfaces, depolarization occurs when the reference plane of incidence is not parallel to the local planes of incidence and scatter. A geometrical optics approximation is used to interpret the results of the double scattered fields for normal incidence near backscatter. The physical interpretation of the results could shed light on the observed fluctuations in the enhanced backscatter phenomenon as the angle of incidence increases from near normal to grazing angles. The results show that double scatter strongly depends upon the mean square slope, the conductivity of the rough surface and the angle of incidence.

  16. Simulation of surface tension in 2D and 3D with smoothed particle hydrodynamics method

    NASA Astrophysics Data System (ADS)

    Zhang, Mingyu

    2010-09-01

    The methods for simulating surface tension with smoothed particle hydrodynamics (SPH) method in two dimensions and three dimensions are developed. In 2D surface tension model, the SPH particle on the boundary in 2D is detected dynamically according to the algorithm developed by Dilts [G.A. Dilts, Moving least-squares particle hydrodynamics II: conservation and boundaries, International Journal for Numerical Methods in Engineering 48 (2000) 1503-1524]. The boundary curve in 2D is reconstructed locally with Lagrangian interpolation polynomial. In 3D surface tension model, the SPH particle on the boundary in 3D is detected dynamically according to the algorithm developed by Haque and Dilts [A. Haque, G.A. Dilts, Three-dimensional boundary detection for particle methods, Journal of Computational Physics 226 (2007) 1710-1730]. The boundary surface in 3D is reconstructed locally with moving least squares (MLS) method. By transforming the coordinate system, it is guaranteed that the interface function is one-valued in the local coordinate system. The normal vector and curvature of the boundary surface are calculated according to the reconstructed boundary surface and then surface tension force can be calculated. Surface tension force acts only on the boundary particle. Density correction is applied to the boundary particle in order to remove the boundary inconsistency. The surface tension models in 2D and 3D have been applied to benchmark tests for surface tension. The ability of the current method applying to the simulation of surface tension in 2D and 3D is proved.

  17. Reflectance for an approximately one-dimensional rough surface that has rms roughness greater than a wavelength

    NASA Astrophysics Data System (ADS)

    Mendeleev, Vladimir Y.; Skovorod'ko, Sergey N.

    2004-02-01

    A relation between the intensity reflectances of approximately one-dimensional and one-dimensional rough surfaces within the diffraction solid angle in the specular direction for normal incidence is derived for an rms roughness greater than a wavelength. The relation shows that the reflectance of an approximately one-dimensional rough surface is proportional to the reflectance of a one-dimension rough surface. The validity of the derived relation is studied for an approximately one-dimensional rough steel surface with an rms roughness of 1.3 μm and a correlation length of 15.2 μm. The wavelength was 0.6328 μm and the angle of incidence was 4°. The reflectance of the rough steel surface was measured and estimated from the derived relation. Satisfactory agreement was found between the estimated and measured reflectance values.

  18. High-resolution, real-time simultaneous 3D surface geometry and temperature measurement.

    PubMed

    An, Yatong; Zhang, Song

    2016-06-27

    This paper presents a method to simultaneously measure three-dimensional (3D) surface geometry and temperature in real time. Specifically, we developed 1) a holistic approach to calibrate both a structured light system and a thermal camera under exactly the same world coordinate system even though these two sensors do not share the same wavelength; and 2) a computational framework to determine the sub-pixel corresponding temperature for each 3D point as well as discard those occluded points. Since the thermal 2D imaging and 3D visible imaging systems do not share the same spectrum of light, they can perform sensing simultaneously in real time: we developed a hardware system that can achieve real-time 3D geometry and temperature measurement at 26 Hz with 768 × 960 points per frame. PMID:27410608

  19. A continuous surface reconstruction method on point cloud captured from a 3D surface photogrammetry system

    SciTech Connect

    Liu, Wenyang; Cheung, Yam; Sabouri, Pouya; Arai, Tatsuya J.; Sawant, Amit; Ruan, Dan

    2015-11-15

    achieved submillimeter reconstruction RMSE under different configurations, demonstrating quantitatively the faith of the proposed method in preserving local structural properties of the underlying surface in the presence of noise and missing measurements, and its robustness toward variations of such characteristics. On point clouds from the human subject, the proposed method successfully reconstructed all patient surfaces, filling regions where raw point coordinate readings were missing. Within two comparable regions of interest in the chest area, similar mean curvature distributions were acquired from both their reconstructed surface and CT surface, with mean and standard deviation of (μ{sub recon} = − 2.7 × 10{sup −3} mm{sup −1}, σ{sub recon} = 7.0 × 10{sup −3} mm{sup −1}) and (μ{sub CT} = − 2.5 × 10{sup −3} mm{sup −1}, σ{sub CT} = 5.3 × 10{sup −3} mm{sup −1}), respectively. The agreement of local geometry properties between the reconstructed surfaces and the CT surface demonstrated the ability of the proposed method in faithfully representing the underlying patient surface. Conclusions: The authors have integrated and developed an accurate level-set based continuous surface reconstruction method on point clouds acquired by a 3D surface photogrammetry system. The proposed method has generated a continuous representation of the underlying phantom and patient surfaces with good robustness against noise and missing measurements. It serves as an important first step for further development of motion tracking methods during radiotherapy.

  20. How surface roughness affects chemical transfer from soil to surface runoff?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil surface roughness affects transport processes, e.g., runoff generation, infiltration, sediment detachment, etc., occurring on the surface. Nevertheless, how soil roughness affects chemical transport is less known. In this study, we partitioned roughness elements into mounds which diverge water ...

  1. High quality surface reconstruction in radiotherapy: Cross-sectional contours to 3D mesh using wavelets.

    PubMed

    Moriconi, S; Scalco, E; Broggi, S; Avuzzi, B; Valdagni, R; Rizzo, G

    2015-08-01

    A novel approach for three-dimensional (3D) surface reconstruction of anatomical structures in radiotherapy (RT) is presented. This is obtained from manual cross-sectional contours by combining both image voxel segmentation processing and implicit surface streaming methods using wavelets. 3D meshes reconstructed with the proposed approach are compared to those obtained from traditional triangulation algorithm. Qualitative and quantitative evaluations are performed in terms of mesh quality metrics. Differences in smoothness, detail and accuracy are observed in the comparison, considering three different anatomical districts and several organs at risk in radiotherapy. Overall best performances were recorded for the proposed approach, regardless the complexity of the anatomical structure. This demonstrates the efficacy of the proposed approach for the 3D surface reconstruction in radiotherapy and allows for further specific image analyses using real biomedical data. PMID:26737226

  2. 3D numerical simulation analysis of passive drag near free surface in swimming

    NASA Astrophysics Data System (ADS)

    Zhan, Jie-min; Li, Tian-zeng; Chen, Xue-bin; Li, Yok-sheung; Wai, Wing-hong Onyx

    2015-04-01

    The aim of this work is to build a 3D numerical model to study the characteristics of passive drag on competitive swimmers taking into account the impact of the free surface. This model solves the 3D incompressible Navier-Stokes equations using RNG k- ɛ turbulence closure. The volume of fluid (VOF) method is used to locate the free surface. The 3D virtual model is created by Computer Aided Industrial Design (CAID) software, Rhinoceros. Firstly, a specific posture of swimming is studied. The simulation results are in good agreement with the data from mannequin towing experiments. The effects of a swimmer's arms and legs positions on swimming performance are then studied. Finally, it is demonstrated that the present method is capable of simulating gliding near the free surface.

  3. On the Effects of Surface Roughness on Boundary Layer Transition

    NASA Technical Reports Server (NTRS)

    Choudhari, Meelan M.; Li, Fei; Chang, Chau-Lyan; Edwards, Jack

    2009-01-01

    Surface roughness can influence laminar-turbulent transition in many different ways. This paper outlines selected analyses performed at the NASA Langley Research Center, ranging in speed from subsonic to hypersonic Mach numbers and highlighting the beneficial as well as adverse roles of the surface roughness in technological applications. The first theme pertains to boundary-layer tripping on the forebody of a hypersonic airbreathing configuration via a spanwise periodic array of trip elements, with the goal of understanding the physical mechanisms underlying roughness-induced transition in a high-speed boundary layer. The effect of an isolated, finite amplitude roughness element on a supersonic boundary layer is considered next. The other set of flow configurations examined herein corresponds to roughness based laminar flow control in subsonic and supersonic swept wing boundary layers. A common theme to all of the above configurations is the need to apply higher fidelity, physics based techniques to develop reliable predictions of roughness effects on laminar-turbulent transition.

  4. Scaling of surface roughness in perfectly plastic disordered media

    SciTech Connect

    Barai, Pallab; Nukala, Phani K; Sampath, Rahul S; Simunovic, Srdjan

    2010-01-01

    This paper investigates surface roughness characteristics of localized plastic yield surface in a perfectly plastic disordered material. We model the plastic disordered material using perfectly plastic random spring model. Our results indicate that plasticity in a disordered material evolves in a diffusive manner until macroscopic yielding, which is in contrast to the localized failure observed in brittle fracture of disordered materials. On the other hand, the height-height fluctuations of the plastic yield surfaces generated by the spring model exhibit roughness exponents similar to those obtained in the brittle fracture of disordered materials, albeit anomalous scaling of plastic surface roughness is not observed. The local and global roughness exponents ({zeta}{sub loc} and {zeta}, respectively) are equal to each other, and the two-dimensional crack roughness exponent is estimated to be {zeta}{sub loc} = {zeta} = 0.67 {+-} 0.03. The probability density distribution p[{Delta}h({ell})] of the height differences {Delta}h({ell}) = [h(x+{ell})-h(x)] of the crack profile follows a Gaussian distribution.

  5. Simulation of synthetic gecko arrays shearing on rough surfaces

    PubMed Central

    Gillies, Andrew G.; Fearing, Ronald S.

    2014-01-01

    To better understand the role of surface roughness and tip geometry in the adhesion of gecko synthetic adhesives, a model is developed that attempts to uncover the relationship between surface feature size and the adhesive terminal feature shape. This model is the first to predict the adhesive behaviour of a plurality of hairs acting in shear on simulated rough surfaces using analytically derived contact models. The models showed that the nanoscale geometry of the tip shape alters the macroscale adhesion of the array of fibres by nearly an order of magnitude, and that on sinusoidal surfaces with amplitudes much larger than the nanoscale features, spatula-shaped features can increase adhesive forces by 2.5 times on smooth surfaces and 10 times on rough surfaces. Interestingly, the summation of the fibres acting in concert shows behaviour much more complex that what could be predicted with the pull-off model of a single fibre. Both the Johnson–Kendall–Roberts and Kendall peel models can explain the experimentally observed frictional adhesion effect previously described in the literature. Similar to experimental results recently reported on the macroscale features of the gecko adhesive system, adhesion drops dramatically when surface roughness exceeds the size and spacing of the adhesive fibrillar features. PMID:24694893

  6. Simulation of synthetic gecko arrays shearing on rough surfaces.

    PubMed

    Gillies, Andrew G; Fearing, Ronald S

    2014-06-01

    To better understand the role of surface roughness and tip geometry in the adhesion of gecko synthetic adhesives, a model is developed that attempts to uncover the relationship between surface feature size and the adhesive terminal feature shape. This model is the first to predict the adhesive behaviour of a plurality of hairs acting in shear on simulated rough surfaces using analytically derived contact models. The models showed that the nanoscale geometry of the tip shape alters the macroscale adhesion of the array of fibres by nearly an order of magnitude, and that on sinusoidal surfaces with amplitudes much larger than the nanoscale features, spatula-shaped features can increase adhesive forces by 2.5 times on smooth surfaces and 10 times on rough surfaces. Interestingly, the summation of the fibres acting in concert shows behaviour much more complex that what could be predicted with the pull-off model of a single fibre. Both the Johnson-Kendall-Roberts and Kendall peel models can explain the experimentally observed frictional adhesion effect previously described in the literature. Similar to experimental results recently reported on the macroscale features of the gecko adhesive system, adhesion drops dramatically when surface roughness exceeds the size and spacing of the adhesive fibrillar features. PMID:24694893

  7. The Aerodynamic Characteristics of Airfoils as Affected by Surface Roughness

    NASA Technical Reports Server (NTRS)

    HOCKER RAY W

    1933-01-01

    The effect on airfoil characteristics of surface roughness of varying degrees and types at different locations on an airfoil was investigated at high values of the Reynolds number in a variable density wind tunnel. Tests were made on a number of National Advisory Committee for Aeronautics (NACA) 0012 airfoil models on which the nature of the surface was varied from a rough to a very smooth finish. The effect on the airfoil characteristics of varying the location of a rough area in the region of the leading edge was also investigated. Airfoils with surfaces simulating lap joints were also tested. Measurable adverse effects were found to be caused by small irregularities in airfoil surfaces which might ordinarily be overlooked. The flow is sensitive to small irregularities of approximately 0.0002c in depth near the leading edge. The tests made on the surfaces simulating lap joints indicated that such surfaces cause small adverse effects. Additional data from earlier tests of another symmetrical airfoil are also included to indicate the variation of the maximum lift coefficient with the Reynolds number for an airfoil with a polished surface and with a very rough one.

  8. A rough-surface thermophysical model for airless planets

    SciTech Connect

    Spencer, J.R. )

    1990-01-01

    A model for determining diurnal temperatures in spherical-section depressions and which encompasses both subsurface heat-flow and direct and scattered sunlight effects is presently applied to the disk-integrated thermal emission of a rough planetary surface with nonzero thermal inertia. Attention is given to the variation with roughness and thermal inertia of the beaming parameter eta, which characterizes zero-phase thermal emission by comparison with a smooth, nonrotating body and is almost independent of albedo for a given surface roughness. The thermal phase curve of Ceres is noted to be well matched by the model features of (1) prograde rotation, (2) 44-deg rms surface slope, and (3) a thermal inertia that is 30 percent of the lunar value. 23 refs.

  9. Scattering from a rough surface in presence of atmospheric turbulence

    NASA Astrophysics Data System (ADS)

    Basu, Santasri; Hyde, Milo W.; McCrae, Jack E.; Fiorino, Steven T.

    2013-05-01

    A Gaussian Schell Model (GSM) might be a convenient way to model extended beacons created on diffuse targets. Earlier, we used a full wave computational technique called the Method of Moments (MoM) to evaluate the scattered field from a rough impedance surface in vacuum. The MoM model showed several deviations from GSM. The present work uses a simulation approach based on physical optics approximation to study the scattering behavior in presence of atmospheric turbulence. A fully coherent beam is propagated through weak turbulence and is incident on the rough surface. The light scattered from the rough surface is again propagated through turbulence back to the source plane and the properties of the scattered radiation are studied through numerical simulations. The simulation results are compared with a GSM.

  10. A rough-surface thermophysical model for airless planets

    NASA Technical Reports Server (NTRS)

    Spencer, John R.

    1990-01-01

    A model for determining diurnal temperatures in spherical-section depressions and which encompasses both subsurface heat-flow and direct and scattered sunlight effects is presently applied to the disk-integrated thermal emission of a rough planetary surface with nonzero thermal inertia. Attention is given to the variation with roughness and thermal inertia of the beaming parameter eta, which characterizes zero-phase thermal emission by comparison with a smooth, nonrotating body and is almost independent of albedo for a given surface roughness. The thermal phase curve of Ceres is noted to be well matched by the model features of (1) prograde rotation, (2) 44-deg rms surface slope, and (3) a thermal inertia that is 30 percent of the lunar value.

  11. Process entanglement as a neuronal anchorage mechanism to rough surfaces

    NASA Astrophysics Data System (ADS)

    Sorkin, Raya; Greenbaum, Alon; David-Pur, Moshe; Anava, Sarit; Ayali, Amir; Ben-Jacob, Eshel; Hanein, Yael

    2009-01-01

    The organization of neurons and glia cells on substrates composed of pristine carbon nanotube islands was investigated using high resolution scanning electron microscopy, immunostaining and confocal microscopy. Neurons were found bound and preferentially anchored to the rough surfaces; moreover, the morphology of the neuronal processes on the small, isolated islands of high density carbon nanotubes was found to be conspicuously curled and entangled. We further demonstrate that the roughness of the surface must match the diameter of the neuronal processes in order to allow them to bind. The results presented here suggest that entanglement, a mechanical effect, may constitute an additional mechanism by which neurons (and possibly other cell types) anchor themselves to rough surfaces. Understanding the nature of the interface between neurons and carbon nanotubes is essential to effectively harness carbon nanotube technology in neurological applications such as neuro-prosthetic and retinal electrodes.

  12. Measurement and modeling of rough surface effects on terahertz spectroscopy

    NASA Astrophysics Data System (ADS)

    Henry, S. C.; Schecklman, S.; Kniffin, G. P.; Zurk, L. M.; Chen, A.

    2010-02-01

    Recent improvements in sensing technology have driven new research areas within the terahertz (THz) portion of the electromagnetic (EM) spectrum. While there are several promising THz applications, several outstanding technical challenges need to be addressed before robust systems can be deployed. A particularly compelling application is the potential use of THz reflection spectroscopy for stand-off detection of drugs and explosives. A primary challenge for this application is to have sufficient signal-to-noise ratio (SNR) to allow spectroscopic identification of the target material, and surface roughness can have an impact on identification. However, scattering from a rough surface may be observed at all angles, suggesting diffuse returns can be used in robust imaging of non-cooperative targets. Furthermore, the scattering physics can also distort the reflection spectra, complicating classification algorithms. In this work, rough surface scattering effects were first isolated by measuring diffuse scattering for gold-coated sandpaper of varying roughness. Secondly, we measured scattering returns from a rough sample with a spectral signature, namely α-lactose monohydrate mixed with Teflon and pressed with sandpaper to introduce controlled roughness. For both the specular and diffuse reflection measurements, the application of traditional spectroscopy techniques provided the ability to resolve the 0.54 THz absorption peak. These results are compared with results from a smooth surface. Implications of the results on the ability to detect explosives with THz reflection spectroscopy are presented and discussed. In addition, the Small Perturbation Method (SPM) is employed to predict backscatter from lactose with a small amount of roughness.

  13. Light depolarization in off-specular reflection on submicro rough metal surfaces with imperfectly random roughness.

    PubMed

    Liu, Linsheng; Li, Xuefeng; Nonaka, Kazuhiro

    2015-02-01

    Depolarization at a rough surface relates to its roughness and irregularity (e.g., sags and crests) besides the material property. However, there is still lack of general theory to clearly describe the relationship between depolarization ratios and surface conditions, and one important reason is that the mechanism of depolarization relates to geometric parameters such as microcosmic height/particle distributions of sub-micro to nm levels. To study the mechanism in more detail, a compact laser instrument is developed, and depolarization information of a linearly polarized incident light is used for analyzing the roughness, during which a He-Ne laser source (λ = 632.8 nm) is used. Three nickel specimens with RMS roughness (Rq) less than λ/4 are fabricated and tested. Six different areas in each specimen are characterized in detail using an AFM. Rq are in the range of 34.1-155.0 nm, and the heights are non-Gaussian distribution in the first specimen and near-Gaussian distribution in the others. Off-specular inspection is carried out exactly on these 18 characterized areas, and results show that the cross-polarization ratios match quite well with Rq values of the first sample that has Rq ≤ λ/10 (or Rt ≤ λ), while they match well with maximum height, Rt, values of the other two that have Rt > λ (the maximum derivation is 11%). In addition, since this instrument is simple, portable, stable, and low-cost, it has great potential for practical online roughness testing after a linear calibration. PMID:25725823

  14. Surface roughness of orthodontic band cements with different compositions

    PubMed Central

    van de SANDE, Françoise Hélène; da SILVA, Adriana Fernandes; MICHELON, Douver; PIVA, Evandro; CENCI, Maximiliano Sérgio; DEMARCO, Flávio Fernando

    2011-01-01

    Objectives The present study evaluated comparatively the surface roughness of four orthodontic band cements after storage in various solutions. Material and Methods eight standardized cylinders were made from 4 materials: zinc phosphate cement (ZP), compomer (C), resin-modified glass ionomer cement (RMGIC) and resin cement (RC). Specimens were stored for 24 h in deionized water and immersed in saline (pH 7.0) or 0.1 M lactic acid solution (pH 4.0) for 15 days. Surface roughness readings were taken with a profilometer (Surfcorder SE1200) before and after the storage period. Data were analyzed by two-way ANOVA and Tukey's test (comparison among cements and storage solutions) or paired t-test (comparison before and after the storage period) at 5% significance level. Results The values for average surface roughness were statistically different (p<0.001) among cements at both baseline and after storage. The roughness values of cements in a decreasing order were ZP>RMGIC>C>R (p<0.001). After 15 days, immersion in lactic acid solution resulted in the highest surface roughness for all cements (p<0.05), except for the RC group (p>0.05). Compared to the current threshold (0.2 µm) related to biofilm accumulation, both RC and C remained below the threshold, even after acidic challenge by immersion in lactic acid solution. Conclusions Storage time and immersion in lactic acid solution increased the surface roughness of the majority of the tested cements. RC presented the smoothest surface and it was not influenced by storage conditions. PMID:21625737

  15. surf3d: A 3-D finite-element program for the analysis of surface and corner cracks in solids subjected to mode-1 loadings

    NASA Technical Reports Server (NTRS)

    Raju, I. S.; Newman, J. C., Jr.

    1993-01-01

    A computer program, surf3d, that uses the 3D finite-element method to calculate the stress-intensity factors for surface, corner, and embedded cracks in finite-thickness plates with and without circular holes, was developed. The cracks are assumed to be either elliptic or part eliptic in shape. The computer program uses eight-noded hexahedral elements to model the solid. The program uses a skyline storage and solver. The stress-intensity factors are evaluated using the force method, the crack-opening displacement method, and the 3-D virtual crack closure methods. In the manual the input to and the output of the surf3d program are described. This manual also demonstrates the use of the program and describes the calculation of the stress-intensity factors. Several examples with sample data files are included with the manual. To facilitate modeling of the user's crack configuration and loading, a companion program (a preprocessor program) that generates the data for the surf3d called gensurf was also developed. The gensurf program is a three dimensional mesh generator program that requires minimal input and that builds a complete data file for surf3d. The program surf3d is operational on Unix machines such as CRAY Y-MP, CRAY-2, and Convex C-220.

  16. Automated 3D Damaged Cavity Model Builder for Lower Surface Acreage Tile on Orbiter

    NASA Technical Reports Server (NTRS)

    Belknap, Shannon; Zhang, Michael

    2013-01-01

    The 3D Automated Thermal Tool for Damaged Acreage Tile Math Model builder was developed to perform quickly and accurately 3D thermal analyses on damaged lower surface acreage tiles and structures beneath the damaged locations on a Space Shuttle Orbiter. The 3D model builder created both TRASYS geometric math models (GMMs) and SINDA thermal math models (TMMs) to simulate an idealized damaged cavity in the damaged tile(s). The GMMs are processed in TRASYS to generate radiation conductors between the surfaces in the cavity. The radiation conductors are inserted into the TMMs, which are processed in SINDA to generate temperature histories for all of the nodes on each layer of the TMM. The invention allows a thermal analyst to create quickly and accurately a 3D model of a damaged lower surface tile on the orbiter. The 3D model builder can generate a GMM and the correspond ing TMM in one or two minutes, with the damaged cavity included in the tile material. A separate program creates a configuration file, which would take a couple of minutes to edit. This configuration file is read by the model builder program to determine the location of the damage, the correct tile type, tile thickness, structure thickness, and SIP thickness of the damage, so that the model builder program can build an accurate model at the specified location. Once the models are built, they are processed by the TRASYS and SINDA.

  17. Effect of Surface Roughness on Characteristics of Spherical Shock Waves

    NASA Technical Reports Server (NTRS)

    Huber, Paul W.; McFarland, Donald R.

    1959-01-01

    Measurements of peak overpressure and Mach stem height were made at four burst heights. Data were obtained with instrumentation capable of directly observing the variation of shock wave movement with time. Good similarity of free air shock peak overpressure with larger scale data was found to exist. The net effect of surface roughness on shock peak overpressures slightly. Surface roughness delayed the Mach stem formation at the greatest charge height and lowered the growth at all burst heights. A similarity parameter was found which approximately correlates the triple point path at different burst heights.

  18. Scanning tunneling microscopy on rough surfaces-quantitative image analysis

    NASA Astrophysics Data System (ADS)

    Reiss, G.; Brückl, H.; Vancea, J.; Lecheler, R.; Hastreiter, E.

    1991-07-01

    In this communication, the application of scanning tunneling microscopy (STM) for a quantitative evaluation of roughnesses and mean island sizes of polycrystalline thin films is discussed. Provided strong conditions concerning the resolution are satisfied, the results are in good agreement with standard techniques as, for example, transmission electron microscopy. Owing to its high resolution, STM can supply a better characterization of surfaces than established methods, especially concerning the roughness. Microscopic interpretations of surface dependent physical properties thus can be considerably improved by a quantitative analysis of STM images.

  19. Adhesion: role of bulk viscoelasticity and surface roughness.

    PubMed

    Lorenz, B; Krick, B A; Mulakaluri, N; Smolyakova, M; Dieluweit, S; Sawyer, W G; Persson, B N J

    2013-06-01

    We study the adhesion between smooth polydimethylsiloxane (PDMS) rubber balls and smooth and rough poly(methyl methacrylate) (PMMA) surfaces, and between smooth silicon nitride balls and smooth PDMS surfaces. From the measured viscoelastic modulus of the PDMS rubber we calculate the viscoelastic contribution to the crack-opening propagation energy γeff(v,T) for a wide range of crack tip velocities v and for several temperatures T. The Johnson-Kendall-Roberts (JKR) contact mechanics theory is used to analyze the ball pull-off force data, and γeff(v,T) is obtained for smooth and rough surfaces. We conclude that γeff(v,T) has contributions of similar magnitude from both the bulk viscoelastic energy dissipation close to the crack tip, and from the bond-breaking process at the crack tip. The pull-off force on the rough surfaces is strongly reduced compared to that of the flat surface, which we attribute mainly to the decrease in the area of contact on the rough surfaces. PMID:23649298

  20. Adhesion: role of bulk viscoelasticity and surface roughness

    NASA Astrophysics Data System (ADS)

    Lorenz, B.; Krick, B. A.; Mulakaluri, N.; Smolyakova, M.; Dieluweit, S.; Sawyer, W. G.; Persson, B. N. J.

    2013-06-01

    We study the adhesion between smooth polydimethylsiloxane (PDMS) rubber balls and smooth and rough poly(methyl methacrylate) (PMMA) surfaces, and between smooth silicon nitride balls and smooth PDMS surfaces. From the measured viscoelastic modulus of the PDMS rubber we calculate the viscoelastic contribution to the crack-opening propagation energy γeff(v,T) for a wide range of crack tip velocities v and for several temperatures T. The Johnson-Kendall-Roberts (JKR) contact mechanics theory is used to analyze the ball pull-off force data, and γeff(v,T) is obtained for smooth and rough surfaces. We conclude that γeff(v,T) has contributions of similar magnitude from both the bulk viscoelastic energy dissipation close to the crack tip, and from the bond-breaking process at the crack tip. The pull-off force on the rough surfaces is strongly reduced compared to that of the flat surface, which we attribute mainly to the decrease in the area of contact on the rough surfaces.

  1. 3D surface reconstruction and visualization of the Drosophila wing imaginal disc at cellular resolution

    NASA Astrophysics Data System (ADS)

    Bai, Linge; Widmann, Thomas; Jülicher, Frank; Dahmann, Christian; Breen, David

    2013-01-01

    Quantifying and visualizing the shape of developing biological tissues provide information about the morphogenetic processes in multicellular organisms. The size and shape of biological tissues depend on the number, size, shape, and arrangement of the constituting cells. To better understand the mechanisms that guide tissues into their final shape, it is important to investigate the cellular arrangement within tissues. Here we present a data processing pipeline to generate 3D volumetric surface models of epithelial tissues, as well as geometric descriptions of the tissues' apical cell cross-sections. The data processing pipeline includes image acquisition, editing, processing and analysis, 2D cell mesh generation, 3D contourbased surface reconstruction, cell mesh projection, followed by geometric calculations and color-based visualization of morphological parameters. In their first utilization we have applied these procedures to construct a 3D volumetric surface model at cellular resolution of the wing imaginal disc of Drosophila melanogaster. The ultimate goal of the reported effort is to produce tools for the creation of detailed 3D geometric models of the individual cells in epithelial tissues. To date, 3D volumetric surface models of the whole wing imaginal disc have been created, and the apicolateral cell boundaries have been identified, allowing for the calculation and visualization of cell parameters, e.g. apical cross-sectional area of cells. The calculation and visualization of morphological parameters show position-dependent patterns of cell shape in the wing imaginal disc. Our procedures should offer a general data processing pipeline for the construction of 3D volumetric surface models of a wide variety of epithelial tissues.

  2. The Effect of Surface Irregularities on Wing Drag. 3; Roughness

    NASA Technical Reports Server (NTRS)

    Hood, Manley J.

    1938-01-01

    Tests have been made in the N.A.C.A. 8-foot high-speed wind tunnel of the drag caused by roughness on the surface of an airfoil of N.A.C.A. 23012 section and 5-foot chord. The tests were made at speeds from 80 t o 500 miles per hour at lift coefficients from 0 to 0.30. For conditions corresponding to high-speed flight, the increase in the drag was 30 percent of the profile drag of the smooth airfoil for the roughness produced by spray painting and 63 percent for the roughness produced. by 0.0037-inch carborundum grains. About one-half the drag increase was caused by the roughness on the forward one-fourth of the airfoil. Sandpapering the painted surface with No. 400 sandpaper made it sufficiently smooth that the drag was no greater than when the surface was polished. In the lower part of the range investigated the drag due to roughness increased rapidly with Reynolds Number.

  3. Modelling surface roughness and rocks in LRO Diviner observations

    NASA Astrophysics Data System (ADS)

    Williams, J.-P.; Hayne, P. O.; Paige, D. A.

    2012-09-01

    The Diviner Lunar Radiometer Experiment on NASA's Lunar Reconnaissance Orbiter (LRO) observes radiance in 7 infrared spectral channels from which brightness temperatures of the lunar surface are derived. In general, Diviner's surface footprint contains small scale variations in temperature. This anisothermality results in different observed brightness temperatures in Diviner's individual channels. A three-dimensional heat diffusion model is used to explore anisothermality in Diviner observations resulting from surface roughness and rocks at multiple length-scales and illumination conditions.

  4. Modeling Images of Natural 3D Surfaces: Overview and Potential Applications

    NASA Technical Reports Server (NTRS)

    Jalobeanu, Andre; Kuehnel, Frank; Stutz, John

    2004-01-01

    Generative models of natural images have long been used in computer vision. However, since they only describe the of 2D scenes, they fail to capture all the properties of the underlying 3D world. Even though such models are sufficient for many vision tasks a 3D scene model is when it comes to inferring a 3D object or its characteristics. In this paper, we present such a generative model, incorporating both a multiscale surface prior model for surface geometry and reflectance, and an image formation process model based on realistic rendering, the computation of the posterior model parameter densities, and on the critical aspects of the rendering. We also how to efficiently invert the model within a Bayesian framework. We present a few potential applications, such as asteroid modeling and Planetary topography recovery, illustrated by promising results on real images.

  5. Generation of 3-D surface maps in waste storage silos using a structured light source

    NASA Technical Reports Server (NTRS)

    Burks, B. L.; Rowe, J. C.; Dinkins, M. A.; Christensen, B.; Selleck, C.; Jacoboski, D.; Markus, R.

    1992-01-01

    Surface contours inside the large waste storage tanks typical of the Department of Energy (DOE) complex are, in general, highly irregular. In addition to pipes and other pieces of equipment in the tanks, the surfaces may have features such as mounds, fissures, crystalline structures, and mixed solid and liquid forms. Prior to remediation activities, it will be necessary to characterize the waste to determine the most effective remediation approaches. Surface contour data will be required both prior to and during remediation. The use is described of a structured light source to generate 3-D surface contour maps of the interior of waste storage silos at the Feed Materials Production Center at Fernald, OH. The landscape inside these large waste storage tanks bears a strong resemblance to some of the landscapes that might be encountered during lunar or planetary exploration. Hence, these terrestrial 3-D mapping techniques may be directly applicable to extraterrestrial exploration. In further development, it will be demonstrated that these 3-D data can be used for robotic task planning just as 3-D surface contour data of a satellite could be used to plan maintenance tasks for a space-based servicing robot.

  6. Soil surface roughness and porosity under different tillage systems

    NASA Astrophysics Data System (ADS)

    Rodriguez-Gonzalez, J.; Saa-Requejo, A.; Gómez, J. A.; Valencia, J. L.; Zarco, P.; Tarquis, A. M.

    2012-04-01

    Both soil porosity and surface elevation can be altered by tillage operation. Even though the surface porosity is an important parameter of a tilled field, however, no practical technique for rapid and non-contact measurement of surface porosity has been developed yet. On the contrary, the surface elevation of tilled soil can be quickly determined with a laser profiler. Working under the assumption that the surface elevation of a tilled field is a complicated superposition of the soil terrain profile at a larger-scale and the roughness at a fine-scale, this study included three aspects: (i) to establish an index (Roughness Index, RI) at a fine-scale to associate the surface roughness with porosity; (ii) to examine the correlation between surface porosity and the proposed RI by three types of tillage treatment in the field; and (iii) to check the scaling/multiscaling behavior among different grid sizes of calculating RI on predicting surface porosity. Consequently, the statistical results from each tilled plot show a strong correlation between the surface porosity and the defined RI in an early stage (ca. 2 days) after tillage. Acknowledgements Funding provided by CEIGRAM (Research Centre for the Management of Agricultural and Environmental Risks)and Spanish Ministerio de Ciencia e Innovación (MICINN) through project AGL2010-21501/AGR is greatly appreciated.

  7. Degree of ice particle surface roughness inferred from polarimetric observations

    NASA Astrophysics Data System (ADS)

    Hioki, Souichiro; Yang, Ping; Baum, Bryan A.; Platnick, Steven; Meyer, Kerry G.; King, Michael D.; Riedi, Jerome

    2016-06-01

    The degree of surface roughness of ice particles within thick, cold ice clouds is inferred from multi-directional, multi-spectral satellite polarimetric observations over oceans, assuming a column-aggregate particle habit. An improved roughness inference scheme is employed that provides a more noise-resilient roughness estimate than the conventional best-fit approach. The improvements include the introduction of a quantitative roughness parameter based on empirical orthogonal function analysis and proper treatment of polarization due to atmospheric scattering above clouds. A global 1-month data sample supports the use of a severely roughened ice habit to simulate the polarized reflectivity associated with ice clouds over ocean. The density distribution of the roughness parameter inferred from the global 1-month data sample and further analyses of a few case studies demonstrate the significant variability of ice cloud single-scattering properties. However, the present theoretical results do not agree with observations in the tropics. In the extratropics, the roughness parameter is inferred but 74 % of the sample is out of the expected parameter range. Potential improvements are discussed to enhance the depiction of the natural variability on a global scale.

  8. Fractal prediction model of thermal contact conductance of rough surfaces

    NASA Astrophysics Data System (ADS)

    Ji, Cuicui; Zhu, Hua; Jiang, Wei

    2013-01-01

    The thermal contact conductance problem is an important issue in studying the heat transfer of engineering surfaces, which has been widely studied since last few decades, and for predicting which many theoretical models have been established. However, the models which have been existed are lack of objectivity due to that they are mostly studied based on the statistical methodology characterization for rough surfaces and simple partition for the deformation formats of contact asperity. In this paper, a fractal prediction model is developed for the thermal contact conductance between two rough surfaces based on the rough surface being described by three-dimensional Weierstrass and Mandelbrot fractal function and assuming that there are three kinds of asperity deformation modes: elastic, elastoplastic and fully plastic. Influences of contact load and contact area as well as fractal parameters and material properties on the thermal contact conductance are investigated by using the presented model. The investigation results show that the thermal contact conductance increases with the increasing of the contact load and contact area. The larger the fractal dimension, or the smaller the fractal roughness, the larger the thermal contact conductance is. The thermal contact conductance increases with decreasing the ratio of Young's elastic modulus to the microhardness. The results obtained indicate that the proposed model can effectively predict the thermal contact conductance at the interface, which provide certain reference to the further study on the issue of heat transfer between contact surfaces.

  9. The Impedance Due to the Roughness of Metallic Surface

    SciTech Connect

    Bane, Karl L.F.; Chao, Alex W.; Ng, Cho-K.; /SLAC

    2011-08-26

    In some future accelerator designs, such as that of the Linear Coherent Light Source (LCLS), the bunch is very short, with an rms length on the order of 10's of microns, and the effective skin depth of the vacuum chamber walls can be very small compared to 1 micron. If the skin depth is small compared to the scale of the surface roughness then the wakefield due to the walls will be dominated by the roughness, and not by the wall resistance. To estimate the wakefields of a rough, metallic surface we begin with a simple, analytical model. Then we apply the MAFIA 3-dimensional, time-domain computer module, T3 to check and find the correct coefficient for the model.

  10. 3D structural analysis of proteins using electrostatic surfaces based on image segmentation

    PubMed Central

    Vlachakis, Dimitrios; Champeris Tsaniras, Spyridon; Tsiliki, Georgia; Megalooikonomou, Vasileios; Kossida, Sophia

    2016-01-01

    Herein, we present a novel strategy to analyse and characterize proteins using protein molecular electro-static surfaces. Our approach starts by calculating a series of distinct molecular surfaces for each protein that are subsequently flattened out, thus reducing 3D information noise. RGB images are appropriately scaled by means of standard image processing techniques whilst retaining the weight information of each protein’s molecular electrostatic surface. Then homogeneous areas in the protein surface are estimated based on unsupervised clustering of the 3D images, while performing similarity searches. This is a computationally fast approach, which efficiently highlights interesting structural areas among a group of proteins. Multiple protein electrostatic surfaces can be combined together and in conjunction with their processed images, they can provide the starting material for protein structural similarity and molecular docking experiments.

  11. Detection and Reconstruction of an Implicit Boundary Surface by Adaptively Expanding A Small Surface Patch in a 3D Image.

    PubMed

    Wang, Lisheng; Wang, Pai; Cheng, Liuhang; Ma, Yu; Wu, Shenzhi; Wang, Yu-Ping; Xu, Zongben

    2014-11-01

    In this paper we propose a novel and easy to use 3D reconstruction method. With the method, users only need to specify a small boundary surface patch in a 2D section image, and then an entire continuous implicit boundary surface (CIBS) can be automatically reconstructed from a 3D image. In the method, a hierarchical tracing strategy is used to grow the known boundary surface patch gradually in the 3D image. An adaptive detection technique is applied to detect boundary surface patches from different local regions. The technique is based on both context dependence and adaptive contrast detection as in the human vision system. A recognition technique is used to distinguish true boundary surface patches from the false ones in different cubes. By integrating these different approaches, a high-resolution CIBS model can be automatically reconstructed by adaptively expanding the small boundary surface patch in the 3D image. The effectiveness of our method is demonstrated by its applications to a variety of real 3D images, where the CIBS with complex shapes/branches and with varying gray values/gradient magnitudes can be well reconstructed. Our method is easy to use, which provides a valuable tool for 3D image visualization and analysis as needed in many applications. PMID:26355329

  12. Speckle size of light scattered from slightly rough cylindrical surfaces

    NASA Astrophysics Data System (ADS)

    Berlasso, Ricardo G.; Quintian, Fernando Perez; Rebollo, Maria A.; Gaggioli, Nestor G.; Brea, Luis Miguel Sanchez; Martinez, Eusebio Bernabeu

    2002-04-01

    This research is an extension of the optical method of quality control presented in a previous paper [Appl. Opt. 39, 5811 (2000)] to the case of slightly rough cylindrical surfaces. Applying the Kirchhoff scalar diffraction theory yields an analytical expression of the autocorrelation function of the intensity scattered from slightly rough cylindrical surfaces. This function, which is related to speckle size and shape, is shown to depend on the surface correlation length, unlike for plane surfaces for which the speckle depends on the illuminated area only. The theoretical expression is compared with that for the speckle produced by the light scattered from a cylindrical bearing and from various high-quality wires, showing that the method allows the correlation lengths of high-quality cylindrical surfaces to be determined.

  13. Controlled surface topography regulates collective 3D migration by epithelial-mesenchymal composite embryonic tissues.

    PubMed

    Song, Jiho; Shawky, Joseph H; Kim, YongTae; Hazar, Melis; LeDuc, Philip R; Sitti, Metin; Davidson, Lance A

    2015-07-01

    Cells in tissues encounter a range of physical cues as they migrate. Probing single cell and collective migratory responses to physically defined three-dimensional (3D) microenvironments and the factors that modulate those responses are critical to understanding how tissue migration is regulated during development, regeneration, and cancer. One key physical factor that regulates cell migration is topography. Most studies on surface topography and cell mechanics have been carried out with single migratory cells, yet little is known about the spreading and motility response of 3D complex multi-cellular tissues to topographical cues. Here, we examine the response to complex topographical cues of microsurgically isolated tissue explants composed of epithelial and mesenchymal cell layers from naturally 3D organized embryos of the aquatic frog Xenopus laevis. We control topography using fabricated micropost arrays (MPAs) and investigate the collective 3D migration of these multi-cellular systems in these MPAs. We find that the topography regulates both collective and individual cell migration and that dense MPAs reduce but do not eliminate tissue spreading. By modulating cell size through the cell cycle inhibitor Mitomycin C or the spacing of the MPAs we uncover how 3D topographical cues disrupt collective cell migration. We find surface topography can direct both single cell motility and tissue spreading, altering tissue-scale processes that enable efficient conversion of single cell motility into collective movement. PMID:25933063

  14. 3D-modeling of Callisto's sputtered surface-exosphere environment

    NASA Astrophysics Data System (ADS)

    Lammer, Helmut; Pfleger, Martin; Lindqvist, Jesper; Lichtenegger, Herbert; Holmström, Mats; Vorburger, Audrey; Wurz, Peter; Barabash, Stas

    2016-04-01

    We study the stoichiometrical release of various surface elements caused by plasma sputtering from an assumed icy and non-icy (i.e., chondritic) surface into the exosphere of the Jovian satellite Callisto. We apply a 3D plasma planetary interaction hybrid model that is used for the evaluation of precipitation maps of magnetospheric H+, O+ and S+ sputter agents onto Callisto's surface. The obtained precipitation maps are then applied to the assumed surface compositions where the related sputter yields are calculated by means of the 2013 SRIM code and are coupled with a 3D exosphere model. Sputtered surface particles are followed on their individual trajectories until they either escape Callisto's gravitational attraction or return to the surface. We study also the effect of collisions between sputter species and ambient O2 molecules which form a tiny atmosphere near the satellite's surface and compare the exosphere densities that are obtained from the 3D model with and without a background gaseous envelope with recent 1D model results. Finally we discuss if the Neutral gas and Ion Mass (NIM) spectrometer, that is part of the Particle Environment Package (PEP) on board of the JUICE mission will be able to detect sputtered particles from Callisto's icy and non-icy surface.

  15. Surface roughness analysis after laser assisted machining of hard to cut materials

    NASA Astrophysics Data System (ADS)

    Przestacki, D.; Jankowiak, M.

    2014-03-01

    Metal matrix composites and Si3N4 ceramics are very attractive materials for various industry applications due to extremely high hardness and abrasive wear resistance. However because of these features they are problematic for the conventional turning process. The machining on a classic lathe still requires special polycrystalline diamond (PCD) or cubic boron nitride (CBN) cutting inserts which are very expensive. In the paper an experimental surface roughness analysis of laser assisted machining (LAM) for two tapes of hard-to-cut materials was presented. In LAM, the surface of work piece is heated directly by a laser beam in order to facilitate, the decohesion of material. Surface analysis concentrates on the influence of laser assisted machining on the surface quality of the silicon nitride ceramic Si3N4 and metal matrix composite (MMC). The effect of the laser assisted machining was compared to the conventional machining. The machining parameters influence on surface roughness parameters was also investigated. The 3D surface topographies were measured using optical surface profiler. The analysis of power spectrum density (PSD) roughness profile were analyzed.

  16. Rate-constrained 3D surface estimation from noise-corrupted multiview depth videos.

    PubMed

    Sun, Wenxiu; Cheung, Gene; Chou, Philip A; Florencio, Dinei; Zhang, Cha; Au, Oscar C

    2014-07-01

    Transmitting compactly represented geometry of a dynamic 3D scene from a sender can enable a multitude of imaging functionalities at a receiver, such as synthesis of virtual images at freely chosen viewpoints via depth-image-based rendering. While depth maps—projections of 3D geometry onto 2D image planes at chosen camera viewpoints-can nowadays be readily captured by inexpensive depth sensors, they are often corrupted by non-negligible acquisition noise. Given depth maps need to be denoised and compressed at the encoder for efficient network transmission to the decoder, in this paper, we consider the denoising and compression problems jointly, arguing that doing so will result in a better overall performance than the alternative of solving the two problems separately in two stages. Specifically, we formulate a rate-constrained estimation problem, where given a set of observed noise-corrupted depth maps, the most probable (maximum a posteriori (MAP)) 3D surface is sought within a search space of surfaces with representation size no larger than a prespecified rate constraint. Our rate-constrained MAP solution reduces to the conventional unconstrained MAP 3D surface reconstruction solution if the rate constraint is loose. To solve our posed rate-constrained estimation problem, we propose an iterative algorithm, where in each iteration the structure (object boundaries) and the texture (surfaces within the object boundaries) of the depth maps are optimized alternately. Using the MVC codec for compression of multiview depth video and MPEG free viewpoint video sequences as input, experimental results show that rate-constrained estimated 3D surfaces computed by our algorithm can reduce coding rate of depth maps by up to 32% compared with unconstrained estimated surfaces for the same quality of synthesized virtual views at the decoder. PMID:24876124

  17. Focus Variation - A New Technology for High Resolution Optical 3D Surface Metrology in the Micro- and Nanometer Range

    NASA Astrophysics Data System (ADS)

    Huber, O.

    2009-04-01

    Focus Variation - A New Technology for High Resolution Optical 3D Surface Metrology in the Micro- and Nanometer Range S. Scherer1, E. Cristea1, O. Huber1, A. Krenn1 1 ALICONA GmbH Graz, Austria The need for increasing accuracy is a characteristic of all geo-applications, and hence of the instruments contributing to obtaining relevant data. Small and fine sensors are being developed, measuring different parameters of our geosystem and requiring continuous validation and calibration. These sensors have often very small components (fine sensors able to sense dust, atmospheric water vapour characteristics, pressure change, gravimeters, satellite micro-components), showing complex topographies including steep flanks and having varying reflective properties. In order to get valid and reliable results, quality assurance of these instruments and sensors is required. The optical technology Focus-Variation, developed by Alicona and added in the latest draft of the upcoming ISO standard 25178, provides high resolution 3D surface metrology even at those complex topographies. The technique of Focus-Variation combines the small depth of focus of an optical system with vertical scanning to provide topographical and color information from the variation of focus. It is used for high-resolution optical 3D surface measurements. The traceable and repeatable measurement results are further being used for e.g. calibration and validation purposes. Some of the characteristics of the technology are: - Measurement of instruments / samples with steep flanks up to 80° - Measurement of materials with strongly varying reflection properties - Measurement of surfaces presenting fine (from 10nm) or strong roughness Here, we present the operating principle and possible applications of the optical 3D measurement system "InfiniteFocus", which is based on the technology of Focus-Variation. With the vertical resolution of up to 10nm, InfiniteFocus yields meaningful form and roughness measurements. The

  18. Reconstructing 3-D skin surface motion for the DIET breast cancer screening system.

    PubMed

    Botterill, Tom; Lotz, Thomas; Kashif, Amer; Chase, J Geoffrey

    2014-05-01

    Digital image-based elasto-tomography (DIET) is a prototype system for breast cancer screening. A breast is imaged while being vibrated, and the observed surface motion is used to infer the internal stiffness of the breast, hence identifying tumors. This paper describes a computer vision system for accurately measuring 3-D surface motion. A model-based segmentation is used to identify the profile of the breast in each image, and the 3-D surface is reconstructed by fitting a model to the profiles. The surface motion is measured using a modern optical flow implementation customized to the application, then trajectories of points on the 3-D surface are given by fusing the optical flow with the reconstructed surfaces. On data from human trials, the system is shown to exceed the performance of an earlier marker-based system at tracking skin surface motion. We demonstrate that the system can detect a 10 mm tumor in a silicone phantom breast. PMID:24770915

  19. 3D surface topography of cylinder liner forecasting during plateau honing process

    NASA Astrophysics Data System (ADS)

    Reizer, R.; Pawlus, P.

    2011-08-01

    Areal surface topographies after plateau honing process were measured. A correlation analysis of surface texture parameters was then carried out. As the results, the following parameters describing plateau honed cylinder 3D surface topography were selected: amplitude Sq, Sz, spatial: Str, Std, hybrid SΔq as well as functional: Spq, Svq and Smq. 3D surface topographies were modeled. The modeled surface topographies were correctly matched to measured ones in 77% of all analyzed cases. The plateau honing experiment was then carried out using an orthogonal selective research plan. Two machining parameters were input variables: coarse honing pressure pv and plateau honing time t. Chosen cylinder liners texture parameters were output values. As the result of the experiment, regression equations connecting plateau honing process parameters pv and t with recommended 3D surface topography parameters were obtained. Finally, cylinder liner surface topographies were predicted for various values of machining parameters. Proper matching accuracy of modeled to measured textures was assured in 67% of analyzed cases.

  20. Active illumination based 3D surface reconstruction and registration for image guided medialization laryngoplasty

    NASA Astrophysics Data System (ADS)

    Jin, Ge; Lee, Sang-Joon; Hahn, James K.; Bielamowicz, Steven; Mittal, Rajat; Walsh, Raymond

    2007-03-01

    The medialization laryngoplasty is a surgical procedure to improve the voice function of the patient with vocal fold paresis and paralysis. An image guided system for the medialization laryngoplasty will help the surgeons to accurately place the implant and thus reduce the failure rates of the surgery. One of the fundamental challenges in image guided system is to accurately register the preoperative radiological data to the intraoperative anatomical structure of the patient. In this paper, we present a combined surface and fiducial based registration method to register the preoperative 3D CT data to the intraoperative surface of larynx. To accurately model the exposed surface area, a structured light based stereo vision technique is used for the surface reconstruction. We combined the gray code pattern and multi-line shifting to generate the intraoperative surface of the larynx. To register the point clouds from the intraoperative stage to the preoperative 3D CT data, a shape priori based ICP method is proposed to quickly register the two surfaces. The proposed approach is capable of tracking the fiducial markers and reconstructing the surface of larynx with no damage to the anatomical structure. We used off-the-shelf digital cameras, LCD projector and rapid 3D prototyper to develop our experimental system. The final RMS error in the registration is less than 1mm.

  1. Nonlinear Actuation Dynamics of Driven Casimir Oscillators with Rough Surfaces

    NASA Astrophysics Data System (ADS)

    Broer, Wijnand; Waalkens, Holger; Svetovoy, Vitaly B.; Knoester, Jasper; Palasantzas, George

    2015-11-01

    At separations below 100 nm, Casimir-Lifshitz forces strongly influence the actuation dynamics of microelectromechanical systems (MEMS) in dry vacuum conditions. For a micron-size plate oscillating near a surface, which mimics a frequently used setup in experiments with MEMS, we show that the roughness of the surfaces significantly influences the qualitative dynamics of the oscillator. Via a combination of analytical and numerical methods, it is shown that surface roughness leads to a clear increase of initial conditions associated with chaotic motion, that eventually lead to stiction between the surfaces. Since stiction leads to a malfunction of MEMS oscillators, our results are of central interest for the design of microdevices. Moreover, stiction is of significance for fundamentally motivated experiments performed with MEMS.

  2. Cleanliness evaluation of rough surfaces with diffuse IR reflectance

    NASA Technical Reports Server (NTRS)

    Pearson, L. H.

    1995-01-01

    Contamination on bonding surfaces has been determined to be a primary cause for degraded bond strength in certain solid rocket motor bondlines. Hydrocarbon and silicone based organic contaminants that are airborne or directly introduced to a surface are a significant source of contamination. Diffuse infrared (IR) reflectance has historically been used as an effective technique for detection of organic contaminants, however, common laboratory methods involving the use of a Fourier transform IR spectrometer (FTIR) are impractical for inspecting the large bonding surface areas found on solid rocket motors. Optical methods involving the use of acousto-optic tunable filters and fixed bandpass optical filters are recommended for increased data acquisition speed. Testing and signal analysis methods are presented which provide for simultaneous measurement of contamination concentration and roughness level on rough metal surfaces contaminated with hydrocarbons.

  3. Imaging SPR combined with stereoscopic 3D tracking to study barnacle cyprid-surface interactions

    NASA Astrophysics Data System (ADS)

    Maleshlijski, S.; Sendra, G. H.; Aldred, N.; Clare, A. S.; Liedberg, B.; Grunze, M.; Ederth, T.; Rosenhahn, A.

    2016-01-01

    Barnacle larvae (cyprids) explore surfaces to identify suitable settlement sites. This process is selective, and cyprids respond to numerous surface cues. To better understand the settlement process, it is desirable to simultaneously monitor both the surface exploration behavior and any close interactions with the surface. Stereoscopic 3D tracking of the cyprids provides quantitative access to surface exploration and pre-settlement rituals. Imaging surface plasmon resonance (SPR) reveals any interactions with the surfaces, such as surface inspection during bipedal walking and deposition of temporary adhesives. We report on a combination of both techniques to bring together information on swimming behavior in the vicinity of the interface and physical interactions of the cyprid with the surface. The technical requirements are described, and we applied the setup to cyprids of Balanus amphitrite. Initial data shows the applicability of the combined instrument to correlate exploration and touchdown events on surfaces with different chemical termination.

  4. Thrust Bearing with Rough Surfaces Lubricated by an Ellis Fluid

    NASA Astrophysics Data System (ADS)

    Walicka, A.; Walicki, E.; Jurczak, P.; Falicki, J.

    2014-11-01

    In the paper the influence of bearing surfaces roughness on the pressure distribution and load-carrying capacity of a thrust bearing is discussed. The equations of motion of an Ellis pseudo-plastic fluid are used to derive the Reynolds equation. After general considerations on the flow in a bearing clearance and using the Christensen theory of hydrodynamic rough lubrication the modified Reynolds equation is obtained. The analytical solutions of this equation for the cases of a squeeze film bearing and an externally pressurized bearing are presented. As a result one obtains the formulae expressing pressure distribution and load-carrying capacity. A thrust radial bearing is considered as a numerical example.

  5. An improved parallel SPH approach to solve 3D transient generalized Newtonian free surface flows

    NASA Astrophysics Data System (ADS)

    Ren, Jinlian; Jiang, Tao; Lu, Weigang; Li, Gang

    2016-08-01

    In this paper, a corrected parallel smoothed particle hydrodynamics (C-SPH) method is proposed to simulate the 3D generalized Newtonian free surface flows with low Reynolds number, especially the 3D viscous jets buckling problems are investigated. The proposed C-SPH method is achieved by coupling an improved SPH method based on the incompressible condition with the traditional SPH (TSPH), that is, the improved SPH with diffusive term and first-order Kernel gradient correction scheme is used in the interior of the fluid domain, and the TSPH is used near the free surface. Thus the C-SPH method possesses the advantages of two methods. Meanwhile, an effective and convenient boundary treatment is presented to deal with 3D multiple-boundary problem, and the MPI parallelization technique with a dynamic cells neighbor particle searching method is considered to improve the computational efficiency. The validity and the merits of the C-SPH are first verified by solving several benchmarks and compared with other results. Then the viscous jet folding/coiling based on the Cross model is simulated by the C-SPH method and compared with other experimental or numerical results. Specially, the influences of macroscopic parameters on the flow are discussed. All the numerical results agree well with available data, and show that the C-SPH method has higher accuracy and better stability for solving 3D moving free surface flows over other particle methods.

  6. In situ surface roughness measurement during PECVD diamond film growth

    SciTech Connect

    Zuiker, C.D.; Gruen, D.M.; Krauss, A.R.

    1995-06-01

    To investigate the development of surface morphology and bulk optical attenuation in diamond films, we have followed diamond film growth on silicon by in-situ laser reflection interferometry in a microwave plasma chemical vapor deposition system. A model for the interpretation of the reflectivity data in terms of film thickness, rms surface roughness and bulk losses due to scattering and absorption is presented. Results are compared with ex situ measurements of these quantities and found to be in good agreement.

  7. Reconstructing White Walls: Multi-View Multi-Shot 3d Reconstruction of Textureless Surfaces

    NASA Astrophysics Data System (ADS)

    Ley, Andreas; Hänsch, Ronny; Hellwich, Olaf

    2016-06-01

    The reconstruction of the 3D geometry of a scene based on image sequences has been a very active field of research for decades. Nevertheless, there are still existing challenges in particular for homogeneous parts of objects. This paper proposes a solution to enhance the 3D reconstruction of weakly-textured surfaces by using standard cameras as well as a standard multi-view stereo pipeline. The underlying idea of the proposed method is based on improving the signal-to-noise ratio in weakly-textured regions while adaptively amplifying the local contrast to make better use of the limited numerical range in 8-bit images. Based on this premise, multiple shots per viewpoint are used to suppress statistically uncorrelated noise and enhance low-contrast texture. By only changing the image acquisition and adding a preprocessing step, a tremendous increase of up to 300% in completeness of the 3D reconstruction is achieved.

  8. 3D Surface Reconstruction of Plant Seeds by Volume Carving: Performance and Accuracies

    PubMed Central

    Roussel, Johanna; Geiger, Felix; Fischbach, Andreas; Jahnke, Siegfried; Scharr, Hanno

    2016-01-01

    We describe a method for 3D reconstruction of plant seed surfaces, focusing on small seeds with diameters as small as 200 μm. The method considers robotized systems allowing single seed handling in order to rotate a single seed in front of a camera. Even though such systems feature high position repeatability, at sub-millimeter object scales, camera pose variations have to be compensated. We do this by robustly estimating the tool center point from each acquired image. 3D reconstruction can then be performed by a simple shape-from-silhouette approach. In experiments we investigate runtimes, theoretically achievable accuracy, experimentally achieved accuracy, and show as a proof of principle that the proposed method is well sufficient for 3D seed phenotyping purposes. PMID:27375628

  9. Potential of ILRIS3D Intensity Data for Planar Surfaces Segmentation

    PubMed Central

    Wang, Chi-Kuei; Lu, Yao-Yu

    2009-01-01

    Intensity value based point cloud segmentation has received less attention because the intensity value of the terrestrial laser scanner is usually altered by receiving optics/hardware or the internal propriety software, which is unavailable to the end user. We offer a solution by assuming the terrestrial laser scanners are stable and the behavior of the intensity value can be characterized. Then, it is possible to use the intensity value for segmentation by observing its behavior, i.e., intensity value variation, pattern and presence of location of intensity values, etc. In this study, experiment results for characterizing the intensity data of planar surfaces collected by ILRIS3D, a terrestrial laser scanner, are reported. Two intensity formats, grey and raw, are employed by ILRIS3D. It is found from the experiment results that the grey intensity has less variation; hence it is preferable for point cloud segmentation. A warm-up time of approximate 1.5 hours is suggested for more stable intensity data. A segmentation method based on the visual cues of the intensity images sequence, which contains consecutive intensity images, is proposed in order to segment the 3D laser points of ILRIS3D. This method is unique to ILRIS3D data and does not require radiometric calibration. PMID:22346726

  10. Surface roughness when diamond turning RSA 905 optical aluminium

    NASA Astrophysics Data System (ADS)

    Otieno, T.; Abou-El-Hossein, K.; Hsu, W. Y.; Cheng, Y. C.; Mkoko, Z.

    2015-08-01

    Ultra-high precision machining is used intensively in the photonics industry for the production of various optical components. Aluminium alloys have proven to be advantageous and are most commonly used over other materials to make various optical components. Recently, the increasing demand from optical systems for optical aluminium with consistent material properties has led to the development of newly modified grades of aluminium alloys produced by rapid solidification in the foundry process. These new aluminium grades are characterised by their finer microstructures and refined mechanical and physical properties. However the machining database of these new optical aluminium grades is limited and more research is still required to investigate their machinability performance when they are diamond turned in ultrahigh precision manufacturing environment. This work investigates the machinability of rapidly solidified aluminium RSA 905 by varying a number of diamond-turning cutting parameters and measuring the surface roughness over a cutting distance of 4 km. The machining parameters varied in this study were the cutting speed, feed rate and depth of cut. The results showed a common trend of decrease in surface roughness with increasing cutting distance. The lowest surface roughness Ra result obtained after 4 km in this study was 3.2 nm. This roughness values was achieved using a cutting speed of 1750 rpm, feed rate of 5 mm/min and depth of cut equal to 25 μm.

  11. Surface roughness from MOLA backscatter pulse-widths

    NASA Astrophysics Data System (ADS)

    Poole, W. D.; Muller, J.-P.; Gupta, S.; Grindrod, P. M.

    2013-09-01

    The time-spread of backscatter laser altimeter pulses, known as pulse-widths, are thought to be capable of being used to infer variations in topography within the footprint of the laser pulse. Here, Mars Orbiter Laser Altimeter (MOLA) pulse-widths have been compared to surface roughness and slope, as measured from high-resolution digital terrain models (DTMs), over different terrains in order to understand how this dataset can be used in the selection of landing and roving sites, and in inferring surface formation and evolution. The results are varied, and suggest that pulsewidths do not respond consistently to variations in terrain. The results show that over Mars Science Laboratory (MSL) candidate landing sites, the pulse-widths can be used as a rough estimate of surface roughness at baselines much larger than the footprint of the pulse. Over much rougher terrain, these pulse-widths respond best to footprint scale slope, which suggests that an additional slope correction for 75 m baselines slopes is required to infer finer scale roughness. However, this is shown not to be the case, as correcting the pulse-widths for 75 m slopes at the MSL candidate sites, and detrending the DTM data, produced poorer results.

  12. Reconstruction Accuracy Assessment of Surface and Underwater 3D Motion Analysis: A New Approach

    PubMed Central

    de Jesus, Kelly; de Jesus, Karla; Figueiredo, Pedro; Vilas-Boas, João Paulo; Fernandes, Ricardo Jorge; Machado, Leandro José

    2015-01-01

    This study assessed accuracy of surface and underwater 3D reconstruction of a calibration volume with and without homography. A calibration volume (6000 × 2000 × 2500 mm) with 236 markers (64 above and 88 underwater control points—with 8 common points at water surface—and 92 validation points) was positioned on a 25 m swimming pool and recorded with two surface and four underwater cameras. Planar homography estimation for each calibration plane was computed to perform image rectification. Direct linear transformation algorithm for 3D reconstruction was applied, using 1600000 different combinations of 32 and 44 points out of the 64 and 88 control points for surface and underwater markers (resp.). Root Mean Square (RMS) error with homography of control and validations points was lower than without it for surface and underwater cameras (P ≤ 0.03). With homography, RMS errors of control and validation points were similar between surface and underwater cameras (P ≥ 0.47). Without homography, RMS error of control points was greater for underwater than surface cameras (P ≤ 0.04) and the opposite was observed for validation points (P ≤ 0.04). It is recommended that future studies using 3D reconstruction should include homography to improve swimming movement analysis accuracy. PMID:26175796

  13. Shear Stress Partitioning in Airflow over Rough Surfaces: Roughness Form Effects and Influence on the Distribution of Shear Stress

    NASA Astrophysics Data System (ADS)

    Gillies, J. A.; Nickling, W. G.; King, J.

    2004-12-01

    Roughness elements distributed across a surface can significantly decrease the entrainment and transport of underlying fine-grained sediments by wind. The parameterization of roughness effects on wind erosion thresholds and sediment transport is critical to the development of models that can provide realistic predictions of sediment thresholds and fluxes due to wind erosion. Raupach et al. (1993) present a model for predicting the protective role of roughness elements in terms of a threshold friction velocity ratio as a function of the roughness geometry and the aerodynamic properties of the surface and roughness elements. The predictive capacity of this model remains uncertain and the work presented here represents part of an on-going effort of our group to improve the parameterization of the Raupach et al. (1993) model. To gain additional understanding of how roughness elements influence the magnitude and nature of the shear stress acting on the surface among the elements and evaluate strength and weaknesses of the roughness density parameter to characterize these effects, a wind tunnel study using model roughness arrays of similar roughness density composed of cube-shaped elements of different length dimensions was undertaken. Roughness density is defined as the total frontal area of all the elements to the total surface area that they occupy. Shear stress in the above element air flow was determined from vertical wind speed profile measurements. Point measurements of near surface shear stresses within the roughness array were made with simple omni-directional skin friction meters in order to investigate the partitioning of shear stress to the intervening surface. The results suggest that the roughness density parameter has severe limitations in describing the shear stress partitioning for these regularly arrayed rough surfaces. For surfaces with identical roughness densities, the surface composed of more and smaller elements was observed to have average and

  14. An Interactive Virtual 3D Tool for Scientific Exploration of Planetary Surfaces

    NASA Astrophysics Data System (ADS)

    Traxler, Christoph; Hesina, Gerd; Gupta, Sanjeev; Paar, Gerhard

    2014-05-01

    In this paper we present an interactive 3D visualization tool for scientific analysis and planning of planetary missions. At the moment scientists have to look at individual camera images separately. There is no tool to combine them in three dimensions and look at them seamlessly as a geologist would do (by walking backwards and forwards resulting in different scales). For this reason a virtual 3D reconstruction of the terrain that can be interactively explored is necessary. Such a reconstruction has to consider multiple scales ranging from orbital image data to close-up surface image data from rover cameras. The 3D viewer allows seamless zooming between these various scales, giving scientists the possibility to relate small surface features (e.g. rock outcrops) to larger geological contexts. For a reliable geologic assessment a realistic surface rendering is important. Therefore the material properties of the rock surfaces will be considered for real-time rendering. This is achieved by an appropriate Bidirectional Reflectance Distribution Function (BRDF) estimated from the image data. The BRDF is implemented to run on the Graphical Processing Unit (GPU) to enable realistic real-time rendering, which allows a naturalistic perception for scientific analysis. Another important aspect for realism is the consideration of natural lighting conditions, which means skylight to illuminate the reconstructed scene. In our case we provide skylights from Mars and Earth, which allows switching between these two modes of illumination. This gives geologists the opportunity to perceive rock outcrops from Mars as they would appear on Earth facilitating scientific assessment. Besides viewing the virtual reconstruction on multiple scales, scientists can also perform various measurements, i.e. geo-coordinates of a selected point or distance between two surface points. Rover or other models can be placed into the scene and snapped onto certain location of the terrain. These are

  15. SU-F-BRF-08: Conformal Mapping-Based 3D Surface Matching and Registration

    SciTech Connect

    Song, Y; Zeng, W; Gu, X; Liu, C

    2014-06-15

    Purpose: Recently, non-rigid 3D surface matching and registration has been used extensively in engineering and medicine. However, matching 3D surfaces undergoing non-rigid deformation accurately is still a challenging mathematical problem. In this study, we present a novel algorithm to address this issue by introducing intrinsic symmetry to the registration Methods: Our computational algorithm for symmetric conformal mapping is divided into three major steps: 1) Finding the symmetric plane; 2) Finding feature points; and 3) Performing cross registration. The key strategy is to preserve the symmetry during the conformal mapping, such that the image on the parameter domain is symmetric and the area distortion factor on the parameter image is also symmetric. Several novel algorithms were developed using different conformal geometric tools. One was based on solving Riemann-Cauchy equation and the other one employed curvature flow Results: Our algorithm was implemented using generic C++ on Windows XP and used conjugate gradient search optimization for acceleration. The human face 3D surface images were acquired using a high speed 3D scanner based on the phase-shifting method. The scanning speed was 30 frames/sec. The image resolution for each frame was 640 × 480. For 3D human face surfaces with different expressions, postures, and boundaries, our algorithms were able to produce consistent result on the texture pattern on the overlapping region Conclusion: We proposed a novel algorithm to improve the robustness of conformal geometric methods by incorporating the symmetric information into the mapping process. To objectively evaluate its performance, we compared it with most existing techniques. Experimental results indicated that our method outperformed all the others in terms of robustness. The technique has a great potential in real-time patient monitoring and tracking in image-guided radiation therapy.

  16. Degree of ice particle surface roughness inferred from polarimetric observations

    NASA Astrophysics Data System (ADS)

    Hioki, S.; Yang, P.; Baum, B. A.; Platnick, S.; Meyer, K. G.; King, M. D.; Riedi, J.

    2015-12-01

    The degree of surface roughness of ice particles within thick, cold ice clouds is inferred from multi-directional, multi-spectral satellite polarimetric observations over oceans, assuming a column-aggregate particle habit. An improved roughness inference scheme is employed in the analysis that provides a more noise-resilient roughness estimate than the conventional best-fit approach. The improvements include the introduction of a quantitative roughness parameter based on empirical orthogonal function analysis and proper treatment of polarization due to atmospheric scattering above clouds. A global one-month data sample supports the use of a severely roughened ice habit to simulate the polarized reflectivity associated with ice clouds over ocean. The density distribution of the roughness parameter inferred from the global one-month data sample and further analyses of a few case studies demonstrate the significant variability of ice cloud single-scattering properties. The present theoretical results are in close agreement with observations in the extratropics but not in the tropics. Potential improvements are discussed to enhance the depiction of the natural variability on a global scale.

  17. Measuring Skew in Average Surface Roughness as a Function of Surface Preparation

    NASA Technical Reports Server (NTRS)

    Stahl, Mark

    2015-01-01

    Characterizing surface roughness is important for predicting optical performance. Better measurement of surface roughness reduces polishing time, saves money and allows the science requirements to be better defined. This study characterized statistics of average surface roughness as a function of polishing time. Average surface roughness was measured at 81 locations using a Zygo white light interferometer at regular intervals during the polishing process. Each data set was fit to a normal and Largest Extreme Value (LEV) distribution; then tested for goodness of fit. We show that the skew in the average data changes as a function of polishing time.

  18. Measuring skew in average surface roughness as a function of surface preparation

    NASA Astrophysics Data System (ADS)

    Stahl, Mark T.

    2015-08-01

    Characterizing surface roughness is important for predicting optical performance. Better measurement of surface roughness reduces polishing time, saves money and allows the science requirements to be better defined. This study characterized statistics of average surface roughness as a function of polishing time. Average surface roughness was measured at 81 locations using a Zygo® white light interferometer at regular intervals during the polishing process. Each data set was fit to a normal and Largest Extreme Value (LEV) distribution; then tested for goodness of fit. We show that the skew in the average data changes as a function of polishing time.

  19. Estimation of planetary surface roughness by HF sounder observation

    NASA Astrophysics Data System (ADS)

    Kobayashi, T.; Ono, T.

    Japanese Martian exploration project "Nozomi" was to carry out several science missions. Plasma Wave Sounder, one of those onboard missions, was an HF sounder to study Martian plasma environment, and Martian surface with the altimetry mode (Oya and Ono, 1998) as well. The altimetry mode observation was studied by means of computer simulations utilizing the KiSS code which had been originally designed to simulate the SELENE Lunar Radar Sounder, a spaceborne HF GPR, based on Kirchhoff approximation theory (Kobayashi, Oya and Ono, 2002). We found an empirical power law for the standard deviation of observed altitudes over Gaussian random rough surfaces: it varies in proportion to the square of the RMS gradient of the surface √{2} hRMS{λ_0, where hRMS and λ_0 are the RMS height of the surface and the correlation distance of the surface, respectively. We applied Geometrical optics to understand this empirical power law, and derived a square power law for the standard deviation of the observed altitude. Our Geometrical optics model assumed the followings: 1) the observed surface is a Gaussian random rough surface, 2) the mean surface is a flat horizontal plane, 3) the observed surface echo is the back scattering echoes, 4) the observed altitude is the mean value of the apparent range of those back scattering echoes. These results imply that HF sounder may be utilized to measure the surface roughness of planetary bodies in terms of the RMS gradient of the surface. Refrence: H. Oya and T. Ono, A new altimeter for Mars land shape observations utilizing the ionospheric sounder system onboard the Planet-B spacecraft, Earth Planets Space, Vol. 50, pp.229-234, 1998 T. Kobayashi, H. Oya, and T. Ono, A-scope analysis of subsurface radar sounding of lunar mare region, Earth Planets Space, Vol. 54, pp.973-982, 2002

  20. Delayed lubricant depletion on liquid-infused randomly rough surfaces

    NASA Astrophysics Data System (ADS)

    Kim, Jeong-Hyun; Rothstein, Jonathan P.

    2016-05-01

    In this study, pressure drops on liquid-infused superhydrophobic surfaces were measured through a microchannel. A number of different superhydrophobic surfaces were prepared and tested. These surfaces included several PDMS surfaces containing precisely patterned microposts and microridges as well as a number of PTFE surfaces with random surface roughness created by sanding the PTFE with different sandpapers. Silicone oil was selected as the lubricant fluid and infused into the microstructures of the superhydrophobic surfaces. Several aqueous glycerin solutions with different viscosities were used as working fluids so that the viscosity ratio between the lubricant and the working fluid could be varied. The lubricant layer trapped within the precisely patterned superhydrophobic PDMS surfaces was found to be easily depleted over a short period of time even in limit of low flow rates and capillary numbers. On the other hand, the randomly rough superhydrophobic PTFE surfaces tested were found to maintain the layer of lubricant oil even at moderately high capillary numbers resulting in drag reduction that was found to increase with increasing viscosity ratio. The pressure drops on the liquid-infused PTFE surfaces were measured over time to determine the longevity of the lubricant layer. The pressure drops for the randomly rough PTFE surfaces were found to initially diminish with time before reaching a short-time plateau which is equivalent to maximum drag reduction. This minimum pressure drop was maintained for at least three hours in all cases regardless of feature size. However, as the depletion of the oil from the lubricant layer was initiated, the pressure drop was observed to grow slowly before reaching a second long-time asymptote which was equivalent to a Wenzel state.

  1. 3D Micropatterned Surface Inspired by Salvinia molesta via Direct Laser Lithography

    PubMed Central

    2015-01-01

    Biomimetic functional surfaces are attracting increasing attention for their relevant technological applications. Despite these efforts, inherent limitations of microfabrication techniques prevent the replication of complex hierarchical microstructures. Using a 3D laser lithography technique, we fabricated a 3D patterned surface bioinspired to Salvinia molesta leaves. The artificial hairs, with crownlike heads, were reproduced by scaling down (ca. 100 times smaller) the dimensions of natural features, so that microscale hairs with submicrometric resolution were attained. The micropatterned surface, in analogy with the natural model, shows interesting properties in terms of hydrophobicity and air retention when submerged by water, even if realized with a hydrophilic material. Furthermore, we successfully demonstrated the capability to promote localized condensation of water droplets from moisture in the atmosphere. PMID:26558410

  2. The variation of ice adhesion strength with substrate surface roughness

    NASA Astrophysics Data System (ADS)

    Hassan, M. F.; Lee, H. P.; Lim, S. P.

    2010-07-01

    The purpose of this study is to determine whether a relationship exists between the mean surface roughness Ra of an aluminium sample and the interfacial bonding strength σ between it and ice that has been frozen onto its surface. A method of forced vibration of a cantilevered composite beam at 10.0 Hz was used to study the interfacial fracture of the metal-ice interface. Low-cost strain gauges instead of piezoelectric PVDF sensors used in other reported studies were used for the adhesion strength measurements. It was found that increasing surface roughness would lead to a higher interfacial bonding strength, although there was no clearly defined mathematical relationship between Ra and σ. For smooth beams, the adhesion strength was found to be between 0.142 and 0.267 MPa, which was in good agreement with the range of values reported in other studies.

  3. Studies on argon collisions with smooth and rough tungsten surfaces.

    PubMed

    Ozhgibesov, M S; Leu, T S; Cheng, C H; Utkin, A V

    2013-09-01

    The aim of this work is to investigate argon scattering behaviors on the smooth and rough tungsten surfaces. Current work deals with numerical simulation of nanoscale heat transfer process accompanying with rarefied gas-solid substrate interactions using molecular dynamics (MD) method. Taking into account that this method is very time consuming, MD simulation using CUDA capable Graphic Cards is implemented. The results found that imperfection of the surface significantly influences on gas atom's momentum change upon collision. However, the energy exchange rate remains unchanged regardless to the surface roughness. This finding is in contrast with the results in extant literatures. We believed the results found in this paper are important for both numerical and theoretical analyses of rarefied gas flow in micro- and nano-systems where the choice of boundary conditions significantly influences flow. PMID:24007943

  4. Hot-rolling nanowire transparent electrodes for surface roughness minimization

    PubMed Central

    2014-01-01

    Silver nanowire transparent electrodes are a promising alternative to transparent conductive oxides. However, their surface roughness presents a problem for their integration into devices with thin layers such as organic electronic devices. In this paper, hot rollers are used to soften plastic substrates with heat and mechanically press the nanowires into the substrate surface. By doing so, the root-mean-square surface roughness is reduced to 7 nm and the maximum peak-to-valley value is 30 nm, making the electrodes suitable for typical organic devices. This simple process requires no additional materials, which results in a higher transparency, and is compatible with roll-to-roll fabrication processes. In addition, the adhesion of the nanowires to the substrate significantly increases. PMID:24994963

  5. Hot-rolling nanowire transparent electrodes for surface roughness minimization

    NASA Astrophysics Data System (ADS)

    Hosseinzadeh Khaligh, Hadi; Goldthorpe, Irene A.

    2014-06-01

    Silver nanowire transparent electrodes are a promising alternative to transparent conductive oxides. However, their surface roughness presents a problem for their integration into devices with thin layers such as organic electronic devices. In this paper, hot rollers are used to soften plastic substrates with heat and mechanically press the nanowires into the substrate surface. By doing so, the root-mean-square surface roughness is reduced to 7 nm and the maximum peak-to-valley value is 30 nm, making the electrodes suitable for typical organic devices. This simple process requires no additional materials, which results in a higher transparency, and is compatible with roll-to-roll fabrication processes. In addition, the adhesion of the nanowires to the substrate significantly increases.

  6. Dynamics of tokamak plasma surface current in 3D ideal MHD model

    NASA Astrophysics Data System (ADS)

    Galkin, Sergei A.; Svidzinski, V. A.; Zakharov, L. E.

    2013-10-01

    Interest in the surface current which can arise on perturbed sharp plasma vacuum interface in tokamaks was recently generated by a few papers (see and references therein). In dangerous disruption events with plasma-touching-wall scenarios, the surface current can be shared with the wall leading to the strong, damaging forces acting on the wall A relatively simple analytic definition of δ-function surface current proportional to a jump of tangential component of magnetic field nevertheless leads to a complex computational problem on the moving plasma-vacuum interface, requiring the incorporation of non-linear 3D plasma dynamics even in one-fluid ideal MHD. The Disruption Simulation Code (DSC), which had recently been developed in a fully 3D toroidal geometry with adaptation to the moving plasma boundary, is an appropriate tool for accurate self-consistent δfunction surface current calculation. Progress on the DSC-3D development will be presented. Self-consistent surface current calculation under non-linear dynamics of low m kink mode and VDE will be discussed. Work is supported by the US DOE SBIR grant #DE-SC0004487.

  7. Dependence of metal-enhanced fluorescence on surface roughness

    NASA Astrophysics Data System (ADS)

    François, Alexandre; Sciacca, Beniamino; Zuber, Agnieszka; Klantsataya, Elizaveta; Monro, Tanya M.

    2014-03-01

    Metal Enhanced Fluorescence (MEF) takes advantage of the coupling between surface plasmons, in either a metallic thin film or metallic nanoparticles, and fluorophores located in proximity of the metal, yielding an increase of the fluorophore emission. While MEF has been widely studied on metallic nanoparticles with the emphasis on creating brighter fluorescent labels, planar surfaces have not benefitted from the same attention. Here we investigate the influence of the surface roughness of a thin metallic film on the fluorescence enhancement. 50nm thick silver films were deposited on glass slides using either thermal evaporation with different evaporation currents or an electroless plating method based on the Tollens reaction to vary the surface roughness. Multiple layers of positively and negatively charged polyelectrolytes were deposited on top of the metallic coating to map out the enhancement factor as function of the gap between the metallic coating and fluorophore molecules covalently bound to the last polyelectrolyte layer. We show that fluorescence is enhanced by the presence of the metallic film, and in particular that the enhancement increases by a factor 3 to 40 for roughness ranging from 3 nm to 8 nm. Although these enhancement factors are modest compared to the enhancement produced by complex metallic nanoparticles or nano-patterned metallic thin films, the thin films used here are capable of supporting a plasmonic wave and offer the possibility of combining different techniques, such as surface plasmon resonance (with its higher refractive index sensitivity compared to localized plasmons) and MEF within a single device.

  8. Capillary adhesion between elastic solids with randomly rough surfaces

    NASA Astrophysics Data System (ADS)

    Persson, B. N. J.

    2008-08-01

    I study how the contact area and the work of adhesion between two elastic solids with randomly rough surfaces depend on the relative humidity. The surfaces are assumed to be hydrophilic, and capillary bridges form at the interface between the solids. For elastically hard solids with relatively smooth surfaces, the area of real contact and therefore also the sliding friction are maximal when there is just enough liquid to fill out the interfacial space between the solids, which typically occurs for dK≈3hrms, where dK is the height of the capillary bridge and hrms the root-mean-square roughness of the (combined) surface roughness profile. For elastically soft solids, the area of real contact is maximal for very low humidity (i.e. small dK), where the capillary bridges are able to pull the solids into nearly complete contact. In both cases, the work of adhesion is maximal (and equal to 2γcosθ, where γ is the liquid surface tension and θ the liquid-solid contact angle) when d_{\\mathrm {K}} \\gg h_{\\mathrm {rms}} , corresponding to high relative humidity.

  9. Data fusion for accurate microscopic rough surface metrology.

    PubMed

    Chen, Yuhang

    2016-06-01

    Data fusion for rough surface measurement and evaluation was analyzed on simulated datasets, one with higher density (HD) but lower accuracy and the other with lower density (LD) but higher accuracy. Experimental verifications were then performed on laser scanning microscopy (LSM) and atomic force microscopy (AFM) characterizations of surface areal roughness artifacts. The results demonstrated that the fusion based on Gaussian process models is effective and robust under different measurement biases and noise strengths. All the amplitude, height distribution, and spatial characteristics of the original sample structure can be precisely recovered, with better metrological performance than any individual measurements. As for the influencing factors, the HD noise has a relatively weaker effect as compared with the LD noise. Furthermore, to enable an accurate fusion, the ratio of LD sampling interval to surface autocorrelation length should be smaller than a critical threshold. In general, data fusion is capable of enhancing the nanometrology of rough surfaces by combining efficient LSM measurement and down-sampled fast AFM scan. The accuracy, resolution, spatial coverage and efficiency can all be significantly improved. It is thus expected to have potential applications in development of hybrid microscopy and in surface metrology. PMID:27058888

  10. SU-E-J-209: Verification of 3D Surface Registration Between Stereograms and CT Images

    SciTech Connect

    Han, T; Gifford, K; Smith, B; Salehpour, M

    2014-06-01

    Purpose: Stereography can provide a visualization of the skin surface for radiation therapy patients. The aim of this study was to verify the registration algorithm in a commercial image analysis software, 3dMDVultus, for the fusion of stereograms and CT images. Methods: CT and stereographic scans were acquired of a head phantom and a deformable phantom. CT images were imported in 3dMDVultus and the surface contours were generated by threshold segmentation. Stereograms were reconstructed in 3dMDVultus. The resulting surfaces were registered with Vultus algorithm and then exported to in-house registration software and compared with four algorithms: rigid, affine, non-rigid iterative closest point (ICP) and b-spline algorithm. RMS (root-mean-square residuals of the surface point distances) error between the registered CT and stereogram surfaces was calculated and analyzed. Results: For the head phantom, the maximum RMS error between registered CT surfaces to stereogram was 6.6 mm for Vultus algorithm, whereas the mean RMS error was 0.7 mm. For the deformable phantom, the maximum RMS error was 16.2 mm for Vultus algorithm, whereas the mean RMS error was 4.4 mm. Non-rigid ICP demonstrated the best registration accuracy, as the mean of RMS errors were both within 1 mm. Conclusion: The accuracy of registration algorithm in 3dMDVultus was verified and exceeded RMS of 2 mm for deformable cases. Non-rigid ICP and b-spline algorithms improve the registration accuracy for both phantoms, especially in deformable one. For those patients whose body habitus deforms during radiation therapy, more advanced nonrigid algorithms need to be used.

  11. Surface roughness, asperity contact and gold RF MEMS switch behavior

    NASA Astrophysics Data System (ADS)

    Rezvanian, O.; Zikry, M. A.; Brown, C.; Krim, J.

    2007-10-01

    Modeling predictions and experimental measurements were obtained to characterize the electro-mechanical response of radio frequency (RF) microelectromechanical (MEM) switches due to variations in surface roughness and finite asperity deformations. Three-dimensional surface roughness profiles were generated, based on a Weierstrass-Mandelbrot fractal representation, to match the measured roughness characteristics of contact bumps of manufactured RF MEMS switches. Contact asperity deformations due to applied contact pressures were then obtained by a creep constitutive formulation. The contact pressure is derived from the interrelated effects of roughness characteristics, material hardening and softening, temperature increases due to Joule heating and contact forces. This modeling framework was used to understand how contact resistance evolves due to changes in the real contact area, the number of asperities in contact, and the temperature and resistivity profiles at the contact points. The numerical predictions were qualitatively consistent with the experimental measurements and observations of how contact resistance evolves as a function of deformation time history. This study provides a framework that is based on integrated modeling and experimental measurements, which can be used in the design of reliable RF MEMS devices with extended life cycles.

  12. Friction and roughness of a melting rock surface

    NASA Astrophysics Data System (ADS)

    Nielsen, S.; di Toro, G.; Griffith, W. A.

    2010-07-01

    Under extreme conditions like those encountered during earthquake slip, frictional melt is likely to occur. It has been observed on ancient faults that the melt is mostly extruded toward local extensional jogs or lateral tension cracks. In the case of laboratory experiments with a rotary shear apparatus, melt is extruded from the sample borders. When this happens, a thin and irregular melt layer is formed whereby the normal load is still in part supported by contact asperities under an incipient yield condition (as in dry friction models), but also, in the interstices between asperities, by the pressure of the viscous fluid wetting the interface. In addition, roughness of the surface is dynamically reshaped by the melting process of an inhomogeneous material (polymineralic rock). In particular, we argue that the roughness of the melting surface decreases with melting rate and temperature gradient perpendicular to the fault. Taking into account the above conditions, we obtain an expression for the average melt layer thickness and viscous pressure that may be used in estimates of friction in the presence of melt. We argue that the ratio of melt thickness to roughness depends on sliding velocity; such a ratio may be used as a gauge of slip-rate during fossil earthquakes on faults bearing pseudotachylite (solidified melt). Finally, we derive an improved analytical solution for friction in the presence of melt including the effect of roughness evolution.

  13. Evaluation Model for Pavement Surface Distress on 3d Point Clouds from Mobile Mapping System

    NASA Astrophysics Data System (ADS)

    Aoki, K.; Yamamoto, K.; Shimamura, H.

    2012-07-01

    This paper proposes a methodology to evaluate the pavement surface distress for maintenance planning of road pavement using 3D point clouds from Mobile Mapping System (MMS). The issue on maintenance planning of road pavement requires scheduled rehabilitation activities for damaged pavement sections to keep high level of services. The importance of this performance-based infrastructure asset management on actual inspection data is globally recognized. Inspection methodology of road pavement surface, a semi-automatic measurement system utilizing inspection vehicles for measuring surface deterioration indexes, such as cracking, rutting and IRI, have already been introduced and capable of continuously archiving the pavement performance data. However, any scheduled inspection using automatic measurement vehicle needs much cost according to the instruments' specification or inspection interval. Therefore, implementation of road maintenance work, especially for the local government, is difficult considering costeffectiveness. Based on this background, in this research, the methodologies for a simplified evaluation for pavement surface and assessment of damaged pavement section are proposed using 3D point clouds data to build urban 3D modelling. The simplified evaluation results of road surface were able to provide useful information for road administrator to find out the pavement section for a detailed examination and for an immediate repair work. In particular, the regularity of enumeration of 3D point clouds was evaluated using Chow-test and F-test model by extracting the section where the structural change of a coordinate value was remarkably achieved. Finally, the validity of the current methodology was investigated by conducting a case study dealing with the actual inspection data of the local roads.

  14. In vivo bioluminescence tomography based on multi-view projection and 3D surface reconstruction

    NASA Astrophysics Data System (ADS)

    Zhang, Shuang; Wang, Kun; Leng, Chengcai; Deng, Kexin; Hu, Yifang; Tian, Jie

    2015-03-01

    Bioluminescence tomography (BLT) is a powerful optical molecular imaging modality, which enables non-invasive realtime in vivo imaging as well as 3D quantitative analysis in preclinical studies. In order to solve the inverse problem and reconstruct inner light sources accurately, the prior structural information is commonly necessary and obtained from computed tomography or magnetic resonance imaging. This strategy requires expensive hybrid imaging system, complicated operation protocol and possible involvement of ionizing radiation. The overall robustness highly depends on the fusion accuracy between the optical and structural information. In this study we present a pure optical bioluminescence tomographic system (POBTS) and a novel BLT method based on multi-view projection acquisition and 3D surface reconstruction. The POBTS acquired a sparse set of white light surface images and bioluminescent images of a mouse. Then the white light images were applied to an approximate surface model to generate a high quality textured 3D surface reconstruction of the mouse. After that we integrated multi-view luminescent images based on the previous reconstruction, and applied an algorithm to calibrate and quantify the surface luminescent flux in 3D.Finally, the internal bioluminescence source reconstruction was achieved with this prior information. A BALB/C mouse with breast tumor of 4T1-fLuc cells mouse model were used to evaluate the performance of the new system and technique. Compared with the conventional hybrid optical-CT approach using the same inverse reconstruction method, the reconstruction accuracy of this technique was improved. The distance error between the actual and reconstructed internal source was decreased by 0.184 mm.

  15. Illustrating Surface Shape in Volume Data via Principal Direction-Driven 3D Line Integral Convolution

    NASA Technical Reports Server (NTRS)

    Interrante, Victoria

    1997-01-01

    The three-dimensional shape and relative depth of a smoothly curving layered transparent surface may be communicated particularly effectively when the surface is artistically enhanced with sparsely distributed opaque detail. This paper describes how the set of principal directions and principal curvatures specified by local geometric operators can be understood to define a natural 'flow' over the surface of an object, and can be used to guide the placement of the lines of a stroke texture that seeks to represent 3D shape information in a perceptually intuitive way. The driving application for this work is the visualization of layered isovalue surfaces in volume data, where the particular identity of an individual surface is not generally known a priori and observers will typically wish to view a variety of different level surfaces from the same distribution, superimposed over underlying opaque structures. By advecting an evenly distributed set of tiny opaque particles, and the empty space between them, via 3D line integral convolution through the vector field defined by the principal directions and principal curvatures of the level surfaces passing through each gridpoint of a 3D volume, it is possible to generate a single scan-converted solid stroke texture that may intuitively represent the essential shape information of any level surface in the volume. To generate longer strokes over more highly curved areas, where the directional information is both most stable and most relevant, and to simultaneously downplay the visual impact of directional information in the flatter regions, one may dynamically redefine the length of the filter kernel according to the magnitude of the maximum principal curvature of the level surface at the point around which it is applied.

  16. A Generalized Approach to the Modeling and Analysis of 3D Surface Morphology in Organisms

    PubMed Central

    Pappas, Janice L.; Miller, Daniel J.

    2013-01-01

    The surface geometry of an organism represents the boundary of its three-dimensional (3D) form and can be used as a proxy for the phenotype. A mathematical approach is presented that describes surface morphology using parametric 3D equations with variables expressed as x, y, z in terms of parameters u, v. Partial differentiation of variables with respect to parameters yields elements of the Jacobian representing tangent lines and planes of every point on the surface. Jacobian elements provide a compact size-free summary of the entire surface, and can be used as variables in principal components analysis to produce a morphospace. Mollusk and echinoid models are generated to demonstrate that whole organisms can be represented in a common morphospace, regardless of differences in size, geometry, and taxonomic affinity. Models can be used to simulate theoretical forms, novel morphologies, and patterns of phenotypic variation, and can also be empirically-based by designing them with reference to actual forms using reverse engineering principles. Although this study uses the Jacobian to summarize models, they can also be analyzed with 3D methods such as eigensurface, spherical harmonics, wavelet analysis, and geometric morphometrics. This general approach should prove useful for exploring broad questions regarding morphological evolution and variation. PMID:24204866

  17. Coupling frontal photopolymerization and surface instabilities for a novel 3D patterning technology

    NASA Astrophysics Data System (ADS)

    Vitale, Alessandra; Hennessy, Matthew; Matar, Omar; Douglas, Jack; Cabral, João

    2015-03-01

    Patterning of soft matter provides an exceptional route for the generation of micro/nanostructured and functional surfaces. We describe a new 3D fabrication process based on coupling frontal photopolymerization (FPP) with precisely controlled, yet spontaneous, interfacial wrinkling. FPP is a complex spatio-temporal process that can lead to well-defined propagating fronts of network formation, both stable and unstable. We investigate this process focusing on the interfacial monomer-to-polymer conversion profile and its wave propagation. A simple coarse-grained model is found to describe remarkably well the planar frontal logarithmic kinetics, capturing the effects of UV light exposure time (or dose) and temperature, as well as the front position. In defined conditions, surface instabilities are introduced and interfere with wave planarity, resulting in the formation of ``minimal'' surfaces with complex 3D geometries. Building on this understanding on the propagation of wavefronts of network formation during photopolymerization, we demonstrate the design and fabrication of 3D patterned polymer materials with tunable shapes with optical and surface functionality.

  18. Measurement of surface roughness and correlation length using dichromatic speckle

    NASA Astrophysics Data System (ADS)

    Deka, M.

    1980-03-01

    A computer simulation study of the dichromatic speckle was conducted and the surface roughness and correlation length of sample surfaces were measured using a stylus instrument and similar measurements with dichromatic speckle. The rms difference of the two speckle intensities was analyzed for spot sizes smaller than, comparable and larger than the correlation length of the surface. The rms roughness of the sample ground glasses was calculated from the data obtained from the stylus instrument. The correlation length was obtained from an online multichannel FFT processor connected to the stylus instrument. The correlation length was estimated from the correlation function. The rms difference between the speckle intensities of two different wavelengths were measured for various spot sizes. For each intensity 64 K data samples was collected and processed in a PDP 11/40 computer. These data were used to calculate the second moment of the monochromatic speckle, the cross correlation of these and the rms difference. The roughness and the correlation length of the surface were estimated from these results. The results obtained from the dichromatic speckle are in good agreement with the values obtained from the stylus instrument.

  19. Influence of surface roughness on water- and oil-repellent surfaces coated with nanoparticles

    NASA Astrophysics Data System (ADS)

    Hsieh, Chien-Te; Chen, Jin-Ming; Kuo, Rong-Rong; Lin, Ta-Sen; Wu, Chu-Fu

    2005-02-01

    Various rough surfaces coated with titanium oxide nanoparticles and perfluoroalkyl methacrylic copolymer were conducted to explore the influence of surface roughness on the performance of water- and oil-repellence. Surface characteristics determined from nitrogen physisorption at -196 °C showed that the surface area and pore volume increased significantly with the extent of nanoparticle ratio, indicating an increase of surface roughness. Due to the surface nano-coating, the maximum contact angles of water and ethylene glycol (EG) droplets increased up to 56 and 48%, respectively, e.g. from 105° to 164° for water droplets and from 96° to 144° for EG droplets. The excellent water- and oil-repellence of the prepared surfaces was ascribed to this increase of surface roughness and fluorinated-contained surface. Compared with Wenzel model, the Cassie model yielded a fairly good fit to the simulation of contact angle with surface roughness. However, a derivation of 3°-10° at higher roughness still existed. This phenomenon was very likely due to the surface heterogeneity with different pore size distributions of the fractal surfaces. In this case, it was unfavorable for super repellency from rough surface with larger mesopore fraction because of its capillary condensation, reflecting that micropore provided more air resistance against wettability.

  20. Algorithms for Accurate and Fast Plotting of Contour Surfaces in 3D Using Hexahedral Elements

    NASA Astrophysics Data System (ADS)

    Singh, Chandan; Saini, Jaswinder Singh

    2016-07-01

    In the present study, Fast and accurate algorithms for the generation of contour surfaces in 3D are described using hexahedral elements which are popular in finite element analysis. The contour surfaces are described in the form of groups of boundaries of contour segments and their interior points are derived using the contour equation. The locations of contour boundaries and the interior points on contour surfaces are as accurate as the interpolation results obtained by hexahedral elements and thus there are no discrepancies between the analysis and visualization results.

  1. 3D scanning electron microscopy applied to surface characterization of fluorosed dental enamel.

    PubMed

    Limandri, Silvina; Galván Josa, Víctor; Valentinuzzi, María Cecilia; Chena, María Emilia; Castellano, Gustavo

    2016-05-01

    The enamel surfaces of fluorotic teeth were studied by scanning electron stereomicroscopy. Different whitening treatments were applied to 25 pieces to remove stains caused by fluorosis and their surfaces were characterized by stereomicroscopy in order to obtain functional and amplitude parameters. The topographic features resulting for each treatment were determined through these parameters. The results obtained show that the 3D reconstruction achieved from the SEM stereo pairs is a valuable potential alternative for the surface characterization of this kind of samples. PMID:26930005

  2. Algorithms for Accurate and Fast Plotting of Contour Surfaces in 3D Using Hexahedral Elements

    NASA Astrophysics Data System (ADS)

    Singh, Chandan; Saini, Jaswinder Singh

    2016-05-01

    In the present study, Fast and accurate algorithms for the generation of contour surfaces in 3D are described using hexahedral elements which are popular in finite element analysis. The contour surfaces are described in the form of groups of boundaries of contour segments and their interior points are derived using the contour equation. The locations of contour boundaries and the interior points on contour surfaces are as accurate as the interpolation results obtained by hexahedral elements and thus there are no discrepancies between the analysis and visualization results.

  3. X-ray fluorescence from rough rocky surfaces of asteroids

    NASA Astrophysics Data System (ADS)

    Okada, T.

    2014-07-01

    X-ray fluorescence (XRF) from orbit is a frequently-used technique to determine the elemental composition of atmosphereless planetary bodies. So far, XRF observations have been conducted for asteroids by the Near-Earth Asteroid Rendezvous Shoemaker mission at (433) Eros [1] and the Hayabusa mission at (25143) Itokawa [2]. There has been difficulties to interpret the XRF data to derive the composition quantitatively. One of the reasons is the surface-roughness effect. We have investigated the XRF intensity influenced by a powdery surface as an analogue to fine regolith [3,4]. However, the surfaces of asteroids explored by the spacecraft at, e.g., (25143) Itokawa or (433) Eros, were not always covered with fine regolith but with pebbles or boulders. Thus, we have performed laboratory experiments to study the roughness effect for rocky surfaces to interpret the XRF observations of those asteroids and the observations of future missions. For the powdery surface, we have obtained the following results: 1) the XRF with lower energy is more effective for the same roughness; 2) the XRF intensity decreases for rougher surfaces but converges to a constant value almost 50--60 % of that of a flat surface; and 3) the XRF intensity decreases for larger phase angles, but does not change so for a varying incident angle when when the phase angle remains fixed. We started the experiments for rocky surfaces to investigate the elemental composition of natural unprepared rocks as well as ground rocks for past and future planetary missions. We prepared the basaltic rock samples with different surface roughness. The roughness of the rock surface is measured with a laser microscope to obtain the three-dimensional surface features and characterize the roughness in <10, 30, 60, 100-micron scales by a rectangular function as in our previous studies. We used the X-ray generator (RIGAKU RINT-2000) using an X-ray tube of Cr-target (V-filter) at 20 kV and 10mA, and detected with the Si-PIN diode

  4. Importance of a 3D forward modeling tool for surface wave analysis methods

    NASA Astrophysics Data System (ADS)

    Pageot, Damien; Le Feuvre, Mathieu; Donatienne, Leparoux; Philippe, Côte; Yann, Capdeville

    2016-04-01

    Since a few years, seismic surface waves analysis methods (SWM) have been widely developed and tested in the context of subsurface characterization and have demonstrated their effectiveness for sounding and monitoring purposes, e.g., high-resolution tomography of the principal geological units of California or real time monitoring of the Piton de la Fournaise volcano. Historically, these methods are mostly developed under the assumption of semi-infinite 1D layered medium without topography. The forward modeling is generally based on Thomson-Haskell matrix based modeling algorithm and the inversion is driven by Monte-Carlo sampling. Given their efficiency, SWM have been transfered to several scale of which civil engineering structures in order to, e.g., determine the so-called V s30 parameter or assess other critical constructional parameters in pavement engineering. However, at this scale, many structures may often exhibit 3D surface variations which drastically limit the efficiency of SWM application. Indeed, even in the case of an homogeneous structure, 3D geometry can bias the dispersion diagram of Rayleigh waves up to obtain discontinuous phase velocity curves which drastically impact the 1D mean velocity model obtained from dispersion inversion. Taking advantages of high-performance computing center accessibility and wave propagation modeling algorithm development, it is now possible to consider the use of a 3D elastic forward modeling algorithm instead of Thomson-Haskell method in the SWM inversion process. We use a parallelized 3D elastic modeling code based on the spectral element method which allows to obtain accurate synthetic data with very low numerical dispersion and a reasonable numerical cost. In this study, we choose dike embankments as an illustrative example. We first show that their longitudinal geometry may have a significant effect on dispersion diagrams of Rayleigh waves. Then, we demonstrate the necessity of 3D elastic modeling as a forward

  5. Direct laser writing of 3D polymer micro/nanostructures on metallic surfaces

    NASA Astrophysics Data System (ADS)

    Rekštytė, Sima; Žukauskas, Albertas; Purlys, Vytautas; Gordienko, Yuri; Malinauskas, Mangirdas

    2013-04-01

    Spectra of fields for applications of polymeric 3D micro/nanostructures are rapidly widening thus demanding the development of versatile precise and efficient fabrication methods that can be used to process a variety of materials and could be implemented to form tiny devices on a variety of surfaces without influencing their structural quality. We present the latest results obtained using laser lithography approach: 3D polymeric structures with submicrometer spatial resolution on different opaque surfaces such as semiconductors (Si) and various metals (Cr, Al, Fe and Ti). The photostructuring was performed using a range of photosensitive materials such as acrylate based AKRE23, acrylated biodegradable PEG-DA-258, epoxy based mr-NIL 6000, hybrid organic-inorganic SZ2080 and Ormocore b59.

  6. Direct laser writing of 3D micro/nanostructures on opaque surfaces

    NASA Astrophysics Data System (ADS)

    Rekštytė, Sima; Žukauskas, Albertas; Purlys, Vytautas; Gordienko, Yuri; Malinauskas, Mangirdas

    2012-06-01

    Spectra of fields for applications of polymeric 3D micro/nanostructures is rapidly widening thus demanding the development of versatile precise and efficient fabrication methods that can be used to process a variety of materials and could be implemented to form tiny devices on a variety of surfaces without influencing their structural quality. We present the latest results obtained using laser lithography approach: 3D polymeric structures with submicrometer spatial resolution on different opaque surfaces such as semiconductors (Si) and various metals (Cr, Al, Fe, Ti). The photostructuring was performed using a range of photosensitive materials such as acrylate based AKRE23, acrylated biodegradable PEG-DA-258, epoxy based mr-NIL 6000, hybrid organic-inorganic SZ2080 and Ormocore b59.

  7. Parallel Imaging of 3D Surface Profile with Space-Division Multiplexing

    PubMed Central

    Lee, Hyung Seok; Cho, Soon-Woo; Kim, Gyeong Hun; Jeong, Myung Yung; Won, Young Jae; Kim, Chang-Seok

    2016-01-01

    We have developed a modified optical frequency domain imaging (OFDI) system that performs parallel imaging of three-dimensional (3D) surface profiles by using the space division multiplexing (SDM) method with dual-area swept sourced beams. We have also demonstrated that 3D surface information for two different areas could be well obtained in a same time with only one camera by our method. In this study, double field of views (FOVs) of 11.16 mm × 5.92 mm were achieved within 0.5 s. Height range for each FOV was 460 µm and axial and transverse resolutions were 3.6 and 5.52 µm, respectively. PMID:26805840

  8. Nonrigid point registration for 2D curves and 3D surfaces and its various applications

    NASA Astrophysics Data System (ADS)

    Wang, Hesheng; Fei, Baowei

    2013-06-01

    A nonrigid B-spline-based point-matching (BPM) method is proposed to match dense surface points. The method solves both the point correspondence and nonrigid transformation without features extraction. The registration method integrates a motion model, which combines a global transformation and a B-spline-based local deformation, into a robust point-matching framework. The point correspondence and deformable transformation are estimated simultaneously by fuzzy correspondence and by a deterministic annealing technique. Prior information about global translation, rotation and scaling is incorporated into the optimization. A local B-spline motion model decreases the degrees of freedom for optimization and thus enables the registration of a larger number of feature points. The performance of the BPM method has been demonstrated and validated using synthesized 2D and 3D data, mouse MRI and micro-CT images. The proposed BPM method can be used to register feature point sets, 2D curves, 3D surfaces and various image data.

  9. Effects of surface roughness on ultrasonic flaw signals

    NASA Astrophysics Data System (ADS)

    Nagy, Peter B.; Adler, Laszlo; Rose, James H.

    In order to demonstrate the effect of random phase modulation on a well-collimated coherent ultrasonic beam, a simple computer simulation is run using the so-called angular-spectrum representation method. The experiments verify the conclusion derived from theoretical results that the ratio of the surface roughness induced transmission loss to the reflection loss at normal incidence is basically a simple constant determined by the sound velocities in the fluid and the solid. The normalized transmission loss is independent of both frequency and rms roughness. It is also almost entirely independent of the densities of the fluid and the solid and, at least in the two angular ranges of high practical importance in ultrasonic NDE, it is marginally sensitive to the autocorrelation length of the surface topography and to the angle of incidence.

  10. Long distance roughness of fracture surfaces in heterogeneous materials

    SciTech Connect

    Hinojosa, M.; Bouchaud, E.; Nghiem, B.

    1999-08-01

    The long distance roughness of fatigue fracture surfaces of a nickel-based superalloy is reported for two samples of different grain size. Statistical analysis over a wide range of length scales, from a few nanometers to a few millimeters, using scanning electron microscopy and atomic force microscopy allows to obtain accurately the self-affine correlation length. Long distance fracture profiles of 14,000 points were obtained and digitized from overlapping electron micrographs at a resolution of 0.22 micrometers/point. The authors have also analyzed the long distance roughness of the mirror zone on a soda-lime glass using atomic force microscopy. In the case of the nickel superalloy, correlation lengths are found to correspond well to the grain size. This result gives information about the mechanism of crack propagation in heterogeneous materials and shows that the correlation length of fracture surfaces is of the order of the largest microstructural heterogeneity.

  11. Direct ambient noise tomography for 3-D near surface shear velocity structure: methodology and applications

    NASA Astrophysics Data System (ADS)

    Yao, H.; Fang, H.; Li, C.; Liu, Y.; Zhang, H.; van der Hilst, R. D.; Huang, Y. C.

    2014-12-01

    Ambient noise tomography has provided essential constraints on crustal and uppermost mantle shear velocity structure in global seismology. Recent studies demonstrate that high frequency (e.g., ~ 1 Hz) surface waves between receivers at short distances can be successfully retrieved from ambient noise cross-correlation and then be used for imaging near surface or shallow crustal shear velocity structures. This approach provides important information for strong ground motion prediction in seismically active area and overburden structure characterization in oil and gas fields. Here we propose a new tomographic method to invert all surface wave dispersion data for 3-D variations of shear wavespeed without the intermediate step of phase or group velocity maps.The method uses frequency-dependent propagation paths and a wavelet-based sparsity-constrained tomographic inversion. A fast marching method is used to compute, at each period, surface wave traveltimes and ray paths between sources and receivers. This avoids the assumption of great-circle propagation that is used in most surface wave tomographic studies, but which is not appropriate in complex media. The wavelet coefficients of the velocity model are estimated with an iteratively reweighted least squares (IRLS) algorithm, and upon iterations the surface wave ray paths and the data sensitivity matrix are updated from the newly obtained velocity model. We apply this new method to determine the 3-D near surface wavespeed variations in the Taipei basin of Taiwan, Hefei urban area and a shale and gas production field in China using the high-frequency interstation Rayleigh wave dispersion data extracted from ambient noisecross-correlation. The results reveal strong effects of off-great-circle propagation of high-frequency surface waves in these regions with above 30% shear wavespeed variations. The proposed approach is more efficient and robust than the traditional two-step surface wave tomography for imaging complex

  12. Quantitative real-time detection of carcinoembryonic antigen (CEA) from pancreatic cyst fluid using 3-D surface molecular imprinting.

    PubMed

    Yu, Yingjie; Zhang, Qi; Buscaglia, Jonathan; Chang, Chung-Chueh; Liu, Ying; Yang, Zhenhua; Guo, Yichen; Wang, Yantian; Levon, Kalle; Rafailovich, Miriam

    2016-07-21

    In this study, a sensitive, yet robust, biosensing system with real-time electrochemical readout was developed. The biosensor system was applied to the detection of carcinoembryonic antigen (CEA), which is a common marker for many cancers such as pancreatic, breast, and colon cancer. Real time detection of CEA during a medical procedure can be used to make critical decisions regarding further surgical intervention. CEA was templated on gold surface (RMS roughness ∼3-4 nm) coated with a hydrophilic self-assembled monolayer (SAM) on the working electrode of an open circuit potentiometric network. The subsequent removal of template CEA makes the biosensor capable of CEA detection based on its specific structure and conformation. The molecular imprinting (MI) biosensor was further calibrated using the potentiometric responses in solutions with known CEA concentrations and a detection limit of 0.5 ng ml(-1) was achieved. Potentiometric sensing was then applied to pancreatic cyst fluid samples obtained from 18 patients when the cyst fluid was also evaluated using ELISA in a certified pathology laboratory. Excellent agreement was obtained between the quantitation of CEA obtained by both the ELISA and MI biosensor detection for CEA. A 3-D MI model, using the natural rms roughness of PVD gold layers, is presented to explain the high degree of sensitivity and linearity observed in those experiments. PMID:27193921

  13. A laminar cortical model of stereopsis and 3D surface perception: closure and da Vinci stereopsis.

    PubMed

    Cao, Yongqiang; Grossberg, Stephen

    2005-01-01

    A laminar cortical model of stereopsis and 3D surface perception is developed and simulated. The model describes how monocular and binocular oriented filtering interact with later stages of 3D boundary formation and surface filling-in in the LGN and cortical areas V1, V2, and V4. It proposes how interactions between layers 4, 3B, and 2/3 in V1 and V2 contribute to stereopsis, and how binocular and monocular information combine to form 3D boundary and surface representations. The model includes two main new developments: (1) It clarifies how surface-to-boundary feedback from V2 thin stripes to pale stripes helps to explain data about stereopsis. This feedback has previously been used to explain data about 3D figure-ground perception. (2) It proposes that the binocular false match problem is subsumed under the Gestalt grouping problem. In particular, the disparity filter, which helps to solve the correspondence problem by eliminating false matches, is realized using inhibitory interneurons as part of the perceptual grouping process by horizontal connections in layer 2/3 of cortical area V2. The enhanced model explains all the psychophysical data previously simulated by Grossberg and Howe (2003), such as contrast variations of dichoptic masking and the correspondence problem, the effect of interocular contrast differences on stereoacuity, Panum's limiting case, the Venetian blind illusion, stereopsis with polarity-reversed stereograms, and da Vinci stereopsis. It also explains psychophysical data about perceptual closure and variations of da Vinci stereopsis that previous models cannot yet explain. PMID:16312095

  14. Using 3D Printers to Model Earth Surface Topography for Increased Student Understanding and Retention

    NASA Astrophysics Data System (ADS)

    Thesenga, David; Town, James

    2014-05-01

    In February 2000, the Space Shuttle Endeavour flew a specially modified radar system during an 11-day mission. The purpose of the multinational Shuttle Radar Topography Mission (SRTM) was to "obtain elevation data on a near-global scale to generate the most complete high-resolution digital topographic database of Earth" by using radar interferometry. The data and resulting products are now publicly available for download and give a view of the landscape removed of vegetation, buildings, and other structures. This new view of the Earth's topography allows us to see previously unmapped or poorly mapped regions of the Earth as well as providing a level of detail that was previously unknown using traditional topographic mapping techniques. Understanding and appreciating the geographic terrain is a complex but necessary requirement for middle school aged (11-14yo) students. Abstract in nature, topographic maps and other 2D renderings of the Earth's surface and features do not address the inherent spatial challenges of a concrete-learner and traditional methods of teaching can at times exacerbate the problem. Technological solutions such as 3D-imaging in programs like Google Earth are effective but lack the tactile realness that can make a large difference in learning comprehension and retention for these young students. First developed in the 1980's, 3D printers were not commercial reality until recently and the rapid rise in interest has driven down the cost. With the advent of sub US1500 3D printers, this technology has moved out of the high-end marketplace and into the local office supply store. Schools across the US and elsewhere in the world are adding 3D printers to their technological workspaces and students have begun rapid-prototyping and manufacturing a variety of projects. This project attempted to streamline the process of transforming SRTM data from a GeoTIFF format by way of Python code. The resulting data was then inputted into a CAD-based program for

  15. Converting surface roughness data into PSD and BSDF

    NASA Astrophysics Data System (ADS)

    Pfisterer, Richard N.

    2012-10-01

    The process to convert raw profilometer data describing surface roughness into PSD and BSDF is discussed, but not well-documented in the open optical engineering literature, and is therefore prone to procedural mistakes. This paper describes the step-by-step numerical process as well as the three "check points" that insure that errors have not been introduced into the calculation. A numerical example is discussed.

  16. 3D surface imaging of the human female torso in upright to supine positions.

    PubMed

    Reece, Gregory P; Merchant, Fatima; Andon, Johnny; Khatam, Hamed; Ravi-Chandar, K; Weston, June; Fingeret, Michelle C; Lane, Chris; Duncan, Kelly; Markey, Mia K

    2015-04-01

    Three-dimensional (3D) surface imaging of breasts is usually done with the patient in an upright position, which does not permit comparison of changes in breast morphology with changes in position of the torso. In theory, these limitations may be eliminated if the 3D camera system could remain fixed relative to the woman's torso as she is tilted from 0 to 90°. We mounted a 3dMDtorso imaging system onto a bariatric tilt table to image breasts at different tilt angles. The images were validated using a rigid plastic mannequin and the metrics compared to breast metrics obtained from five subjects with diverse morphology. The differences between distances between the same fiducial marks differed between the supine and upright positions by less than 1% for the mannequin, whereas the differences for distances between the same fiducial marks on the breasts of the five subjects differed significantly and could be correlated with body mass index and brassiere cup size for each position change. We show that a tilt table-3D imaging system can be used to determine quantitative changes in the morphology of ptotic breasts when the subject is tilted to various angles. PMID:25703742

  17. 3D Surface Imaging of the Human Female Torso in Upright to Supine Positions

    PubMed Central

    Reece, Gregory P.; Merchant, Fatima; Andon, Johnny; Khatam, Hamed; Ravi-Chandar, K.; Weston, June; Fingeret, Michelle C.; Lane, Chris; Duncan, Kelly; Markey, Mia K.

    2015-01-01

    Three-dimensional (3D) surface imaging of breasts is usually done with the patient in an upright position, which does not permit comparison of changes in breast morphology with changes in position of the torso. In theory, these limitations may be eliminated if the 3D camera system could remain fixed relative to the woman’s torso as she is tilted from 0 to 90 degrees. We mounted a 3dMDtorso imaging system onto a bariatric tilt table to image breasts at different tilt angles. The images were validated using a rigid plastic mannequin and the metrics compared to breast metrics obtained from 5 subjects with diverse morphology. The differences between distances between the same fiducial marks differed between the supine and upright positions by less than one percent for the mannequin, whereas the differences for distances between the same fiducial marks on the breasts of the 5 subjects differed significantly and could be correlated with body mass index and brassiere cup size for each position change. We show that a tilt table - 3D imaging system can be used to determine quantitative changes in the morphology of ptotic breasts when the subject is tilted to various angles. PMID:25703742

  18. The roughness of the Martian surface: A scale dependent model

    NASA Technical Reports Server (NTRS)

    Shepard, M. K.; Guinness, E. A.; Arvidson, R. E.

    1993-01-01

    In the coming decade, several lander missions to Mars are planned (e.g., MESUR Pathfinder, MESUR). One of the dangers facing planners of these missions is the rough topography observed at both Viking Lander sites. Both landing sites are ubiquitously covered with meter-scale boulders. Objects of this size pose obvious threats to soft landers, especially at Mars where the distance from Earth causes prohibitive time lags between the transmission of commands and feedback from the spacecraft. An obvious solution is to scout for a 'smooth' site prior to the landing. However, the best resolutions realizable on current and future missions (i.e., Mars Observer) are on the order of several meters. Even at this scale, boulders of 1-2 meters in size are unresolvable. Additionally, the amount of time and spacecraft resources required to search even a small area of the planet are unrealistic given other mission objectives. An alternative is to determine the 'roughness' of the surface at a subpixel scale using bidirectional reflectance observations. Much larger areas of the planet can be searched, and much of the search can easily be automated. The morphology of the martian plains observed by the Viking Landers is physically simple. The surface is covered with a layer (approximately flat lying) of aeolian sediment from which numerous outcrops of bedrock and boulders protrude. This morphology, while simple, will be difficult to characterize from orbit using traditional bidirectional reflectance models for two reasons. First, modeling the surface as facets with Gaussian or exponential slope distributions is not realistic given the morphology described above. Second, the roughness parameter is an 'average' of the roughness at scales ranging from the wavelength of light being scattered to the pixel size of the observation. Thus, there is no definite scale of roughness that can be extracted from the Hapke roughness parameter. Using the concepts of geometric and boolean models

  19. The Influence of Roughness on Gear Surface Fatigue

    NASA Technical Reports Server (NTRS)

    Krantz, Timothy

    2005-01-01

    Gear working surfaces are subjected to repeated rolling and sliding contacts, and often designs require loads sufficient to cause eventual fatigue of the surface. This research provides experimental data and analytical tools to further the understanding of the causal relationship of gear surface roughness to surface fatigue. The research included evaluations and developments of statistical tools for gear fatigue data, experimental evaluation of the surface fatigue lives of superfinished gears with a near-mirror quality, and evaluations of the experiments by analytical methods and surface inspections. Alternative statistical methods were evaluated using Monte Carlo studies leading to a final recommendation to describe gear fatigue data using a Weibull distribution, maximum likelihood estimates of shape and scale parameters, and a presumed zero-valued location parameter. A new method was developed for comparing two datasets by extending the current methods of likelihood-ratio based statistics. The surface fatigue lives of superfinished gears were evaluated by carefully controlled experiments, and it is shown conclusively that superfinishing of gears can provide for significantly greater lives relative to ground gears. The measured life improvement was approximately a factor of five. To assist with application of this finding to products, the experimental condition was evaluated. The fatigue life results were expressed in terms of specific film thickness and shown to be consistent with bearing data. Elastohydrodynamic and stress analyses were completed to relate the stress condition to fatigue. Smooth-surface models do not adequately explain the improved fatigue lives. Based on analyses using a rough surface model, it is concluded that the improved fatigue lives of superfinished gears is due to a reduced rate of near-surface micropitting fatigue processes, not due to any reduced rate of spalling (sub-surface) fatigue processes. To complete the evaluations, surface

  20. Feature, design intention and constraint preservation for direct modeling of 3D freeform surfaces

    NASA Astrophysics Data System (ADS)

    Fu, Luoting; Kara, Levent Burak; Shimada, Kenji

    2012-06-01

    Direct modeling has recently emerged as a suitable approach for 3D free-form shape modeling in industrial design. It has several advantages over the conventional, parametric modeling techniques, including natural user interactions, as well as the underlying, automatic feature-preserving shape deformation algorithms. However, current direct modeling packages still lack several capabilities critical for product design, such as managing aesthetic design intentions, and enforcing dimensional, geometric constraints. In this paper, we describe a novel 3D surface editing system capable of jointly accommodating aesthetic design intentions expressed in the form of surface painting and color-coded annotations, as well as engineering constraints expressed as dimensions. The proposed system is built upon differential coordinates and constrained least squares, and is intended for conceptual design that involves frequent shape tuning and explorations. We also provide an extensive review of the state-of-the-art direct modeling approaches for 3D mesh-based, freeform surfaces, with an emphasis on the two broad categories of shape deformation algorithms developed in the relevant field of geometric modeling. [Figure not available: see fulltext.

  1. State of the art of 3D scanning systems and inspection of textile surfaces

    NASA Astrophysics Data System (ADS)

    Montilla, M.; Orjuela-Vargas, S. A.; Philips, W.

    2014-02-01

    The rapid development of hardware and software in the digital image processing field has boosted research in computer vision for applications in industry. The development of new electronic devices and the tendency to decrease their prices makes possible new developments that few decades ago were possible only in the imagination. This is the case of 3D imaging technology which permits to detect failures in industrial products by inspecting aspects on their 3D surface. In search of an optimal solution for scanning textiles we present in this paper a review of existing techniques for digitizing 3D surfaces. Topographic details of textiles can be obtained by digitizing surfaces using laser line triangulation, phase shifting optical triangulation, projected-light, stereo-vision systems and silhouette analysis. Although we are focused on methods that have been used in the textile industry, we also consider potential mechanisms used for other applications. We discuss the advantages and disadvantages of the evaluated methods and state a summary of potential implementations for the textile industry.

  2. 3D active surfaces for liver segmentation in multisequence MRI images.

    PubMed

    Bereciartua, Arantza; Picon, Artzai; Galdran, Adrian; Iriondo, Pedro

    2016-08-01

    Biopsies for diagnosis can sometimes be replaced by non-invasive techniques such as CT and MRI. Surgeons require accurate and efficient methods that allow proper segmentation of the organs in order to ensure the most reliable intervention planning. Automated liver segmentation is a difficult and open problem where CT has been more widely explored than MRI. MRI liver segmentation represents a challenge due to the presence of characteristic artifacts, such as partial volumes, noise and low contrast. In this paper, we present a novel method for multichannel MRI automatic liver segmentation. The proposed method consists of the minimization of a 3D active surface by means of the dual approach to the variational formulation of the underlying problem. This active surface evolves over a probability map that is based on a new compact descriptor comprising spatial and multisequence information which is further modeled by means of a liver statistical model. This proposed 3D active surface approach naturally integrates volumetric regularization in the statistical model. The advantages of the compact visual descriptor together with the proposed approach result in a fast and accurate 3D segmentation method. The method was tested on 18 healthy liver studies and results were compared to a gold standard made by expert radiologists. Comparisons with other state-of-the-art approaches are provided by means of nine well established quality metrics. The obtained results improve these methodologies, achieving a Dice Similarity Coefficient of 98.59. PMID:27282235

  3. 3D surface scan of biological samples with a Push-broom Imaging Spectrometer

    NASA Astrophysics Data System (ADS)

    Yao, Haibo; Kincaid, Russell; Hruska, Zuzana; Brown, Robert L.; Bhatnagar, Deepak; Cleveland, Thomas E.

    2013-08-01

    The food industry is always on the lookout for sensing technologies for rapid and nondestructive inspection of food products. Hyperspectral imaging technology integrates both imaging and spectroscopy into unique imaging sensors. Its application for food safety and quality inspection has made significant progress in recent years. Specifically, hyperspectral imaging has shown its potential for surface contamination detection in many food related applications. Most existing hyperspectral imaging systems use pushbroom scanning which is generally used for flat surface inspection. In some applications it is desirable to be able to acquire hyperspectral images on circular objects such as corn ears, apples, and cucumbers. Past research describes inspection systems that examine all surfaces of individual objects. Most of these systems did not employ hyperspectral imaging. These systems typically utilized a roller to rotate an object, such as an apple. During apple rotation, the camera took multiple images in order to cover the complete surface of the apple. The acquired image data lacked the spectral component present in a hyperspectral image. This paper discusses the development of a hyperspectral imaging system for a 3-D surface scan of biological samples. The new instrument is based on a pushbroom hyperspectral line scanner using a rotational stage to turn the sample. The system is suitable for whole surface hyperspectral imaging of circular objects. In addition to its value to the food industry, the system could be useful for other applications involving 3-D surface inspection.

  4. Friction and roughness of a melting rock surface

    NASA Astrophysics Data System (ADS)

    Nielsen, Stefan; di Toro, Giulio; Griffith, Ashley

    2010-05-01

    Under extreme conditions like those encountered during earthquake slip, frictional melt is likely to occur. It has been observed on fossil faults that the melt is mostly extruded toward local extensional jogs or lateral tension cracks. A similar condition is reproduced in laboratory experiments with a rotary shear apparatus. When this happens, a thin and irregular melt layer is formed whereby the normal load is still in part supported by contact asperities under an incipient yield condition (as in dry friction models), but also, in the interstices between asperities, by the pressure of the viscous fluid wetting the interface. In addition, roughness of the surface is dynamically reshaped by the melting process of an inhomogeneous material (polymineral rock). In particular, we argue that the roughness decreases with temperature gradient and the melting rate. Taking into account the above conditions, we obtain an expression for the average melt layer thickness and viscous pressure that may be used in estimates of friction in the presence of melt. We argue that the ratio of melt thickness to roughness depends on sliding velocity; such a ratio may be used as a gauge of slip-rate during fossil earthquakes on faults bearing pseudotachylite (solidified melt). Finally, we derive an improved analytical solution for friction in the presence of melt including the effect of roughness evolution.

  5. Correlation Between Eddy Current Signal Noise and Peened Surface Roughness

    NASA Astrophysics Data System (ADS)

    Wendt, S. E.; Hentscher, S. R.; Raithel, D. C.; Nakagawa, N.

    2007-03-01

    For advanced uses of eddy current (EC) NDE models in, e.g., model-assisted POD, there is a need to understand the origin of EC noise sources so that noise estimations can be made for a given set of inspection conditions, in addition to defect signal predictions. This paper focuses on the material-oriented noise sources that exhibit some universality when isolated from electrical and mechanical noises. Specifically, we report on experimental measurements that show explicit correlations between surface roughness and EC noise as seen in post-peen EC measurements of shot-peened roughness specimens. The samples are 3″-by-3″ Inconel 718 and Ti-6A1-4V blocks, pre-polished and shot-peened at Almen intensities ranging from a low of 4N to as high as 16A, created by smaller (˜350 μm) and larger (˜1 mm) diameter zirconium oxide shots. Strong correlations are observed between the Almen intensities and the measured surface roughness. The EC noise correlates equally strongly with the Almen intensities for the superalloy specimens. The correlation for the Ti-alloy samples is only apparent at higher intensities, while being weak for lower intensities, indicating the grain noise dominance for smoother surfaces.

  6. Structure of turbulent wedges created by isolated surface roughness

    NASA Astrophysics Data System (ADS)

    Kuester, Matthew S.; White, Edward B.

    2016-04-01

    Isolated surface roughness in a laminar boundary layer can create a wedge of turbulence that spreads laterally into the surrounding laminar flow. Some recent studies have identified high- and low-speed streaks along the exterior of turbulent wedges. In this experiment, developing turbulent wedges are measured to observe the creation of these streaks. Naphthalene shear stress surface visualization and hotwire measurements are utilized to investigate the details of turbulent wedges created by cylinders in a laminar flat-plate boundary layer. Both the surface visualization and the hotwire measurements show high- and low-speed streaks in the wake of the cylinder that devolve into a turbulent wedge. The turbulent wedge spreading is associated with the emergence of these high- and low-speed streaks along the outside of the wedge. As the wedge evolves in the streamwise direction, these streaks persist inside of the core of the wedge, while new, lower amplitude streaks form along the outside of the wedge. Adding asymmetry to the cylinder moved the virtual origin closer to the roughness and increased the vortex shedding frequency, while adding small-scale roughness features did not strongly affect turbulent wedge development. Intermittency calculations additionally show the origin of the turbulent core inside of the wedge. The structure and spacing of the high-speed streaks along the extremities of the turbulent wedge give insight into the spreading angle of the turbulent wedge.

  7. Correlation Between Eddy Current Signal Noise and Peened Surface Roughness

    SciTech Connect

    Wendt, S. E.; Hentscher, S. R.; Raithel, D. C.; Nakagawa, N.

    2007-03-21

    For advanced uses of eddy current (EC) NDE models in, e.g., model-assisted POD, there is a need to understand the origin of EC noise sources so that noise estimations can be made for a given set of inspection conditions, in addition to defect signal predictions. This paper focuses on the material-oriented noise sources that exhibit some universality when isolated from electrical and mechanical noises. Specifically, we report on experimental measurements that show explicit correlations between surface roughness and EC noise as seen in post-peen EC measurements of shot-peened roughness specimens. The samples are 3''-by-3'' Inconel 718 and Ti-6A1-4V blocks, pre-polished and shot-peened at Almen intensities ranging from a low of 4N to as high as 16A, created by smaller ({approx}350 {mu}m) and larger ({approx}1 mm) diameter zirconium oxide shots. Strong correlations are observed between the Almen intensities and the measured surface roughness. The EC noise correlates equally strongly with the Almen intensities for the superalloy specimens. The correlation for the Ti-alloy samples is only apparent at higher intensities, while being weak for lower intensities, indicating the grain noise dominance for smoother surfaces.

  8. Assessment of Ulcer Wounds Size Using 3D Skin Surface Imaging

    NASA Astrophysics Data System (ADS)

    Hani, Ahmad Fadzil M.; Eltegani, Nejood M.; Hussein, Suraiya H.; Jamil, Adawiyah; Gill, Priya

    In this work 3D surface scans of wounds are used to obtain several measurement including wound top area, true surface area (rue area), depth, and volume for the purpose of assessing the progress of ulcer wounds throughout treatment. KONICA MINOLTA 910 laser scanner is used to obtain the surface scans. The algorithm for estimating top area and true surface area from surface scan can reduce the inaccuracy that might result when using manual method. Two methods for solid construction and volume computation were considered; namely mid-point projection and convex hull approximation (Delaunay tetrahedralization). The performance of convex hull approximation method for volume estimation is improved by performing surface subdivision prior to the approximation. The performance of these algorithms on different patterns of simulated wound models is presented. Furthermore the algorithms are tested in two molded wounds printed using rapid prototyping (RP) technique.

  9. Improvement of PET surface hydrophilicity and roughness through blending

    SciTech Connect

    Kolahchi, Ahmad Rezaei; Ajji, Abdellah; Carreau, Pierre J.

    2015-05-22

    Controlling the adhesion of the polymer surface is a key issue in surface science, since polymers have been a commonly used material for many years. The surface modification in this study includes two different aspects. One is to enhance the hydrophilicity and the other is to create the roughness on the PET film surface. In this study we developed a novel and simple approach to modify polyethylene terephthalate (PET) film surface through polymer blending in twin-screw extruder. One example described in the study uses polyethylene glycol (PEG) in polyethylene terephthalate (PET) host to modify a PET film surface. Low content of polystyrene (PS) as a third component was used in the system to increase the rate of migration of PEG to the surface of the film. Surface enrichment of PEG was observed at the polymer/air interface of the polymer film containing PET-PEG-PS whereas for the PET-PEG binary blend more PEG was distributed within the bulk of the sample. Furthermore, a novel method to create roughness at the PET film surface was proposed. In order to roughen the surface of PET film, a small amount of PKHH phenoxy resin to change PS/PET interfacial tension was used. The compatibility effect of PKHH causes the formation of smaller PS droplets, which were able to migrate more easily through PET matrix. Consequently, resulting in a locally elevated concentration of PS near the surface of the film. The local concentration of PS eventually reached a level where a co-continuous morphology occurred, resulting in theinstabilities on the surface of the film.

  10. Improvement of PET surface hydrophilicity and roughness through blending

    NASA Astrophysics Data System (ADS)

    Kolahchi, Ahmad Rezaei; Ajji, Abdellah; Carreau, Pierre. J.

    2015-05-01

    Controlling the adhesion of the polymer surface is a key issue in surface science, since polymers have been a commonly used material for many years. The surface modification in this study includes two different aspects. One is to enhance the hydrophilicity and the other is to create the roughness on the PET film surface. In this study we developed a novel and simple approach to modify polyethylene terephthalate (PET) film surface through polymer blending in twin-screw extruder. One example described in the study uses polyethylene glycol (PEG) in polyethylene terephthalate (PET) host to modify a PET film surface. Low content of polystyrene (PS) as a third component was used in the system to increase the rate of migration of PEG to the surface of the film. Surface enrichment of PEG was observed at the polymer/air interface of the polymer film containing PET-PEG-PS whereas for the PET-PEG binary blend more PEG was distributed within the bulk of the sample. Furthermore, a novel method to create roughness at the PET film surface was proposed. In order to roughen the surface of PET film, a small amount of PKHH phenoxy resin to change PS/PET interfacial tension was used. The compatibility effect of PKHH causes the formation of smaller PS droplets, which were able to migrate more easily through PET matrix. Consequently, resulting in a locally elevated concentration of PS near the surface of the film. The local concentration of PS eventually reached a level where a co-continuous morphology occurred, resulting in theinstabilities on the surface of the film.

  11. Empirical assessment of the validity limits of the surface wave full ray theory using realistic 3-D Earth models

    NASA Astrophysics Data System (ADS)

    Parisi, Laura; Ferreira, Ana M. G.

    2016-04-01

    The surface wave full ray theory (FRT) is an efficient tool to calculate synthetic waveforms of surface waves. It combines the concept of local modes with exact ray tracing as a function of frequency, providing a more complete description of surface wave propagation than the widely used great circle approximation (GCA). The purpose of this study is to evaluate the ability of the FRT approach to model teleseismic long-period surface waveforms (T ˜ 45-150 s) in the context of current 3-D Earth models to empirically assess its validity domain and its scope for future studies in seismic tomography. To achieve this goal, we compute vertical and horizontal component fundamental mode synthetic Rayleigh waveforms using the FRT, which are compared with calculations using the highly accurate spectral element method. We use 13 global earth models including 3-D crustal and mantle structure, which are derived by successively varying the strength and lengthscale of heterogeneity in current tomographic models. For completeness, GCA waveforms are also compared with the spectral element method. We find that the FRT accurately predicts the phase and amplitude of long-period Rayleigh waves (T ˜ 45-150 s) for almost all the models considered, with errors in the modelling of the phase (amplitude) of Rayleigh waves being smaller than 5 per cent (10 per cent) in most cases. The largest errors in phase and amplitude are observed for T ˜ 45 s and for the three roughest earth models considered that exhibit shear wave anomalies of up to ˜20 per cent, which is much larger than in current global tomographic models. In addition, we find that overall the GCA does not predict Rayleigh wave amplitudes well, except for the longest wave periods (T ˜ 150 s) and the smoothest models considered. Although the GCA accurately predicts Rayleigh wave phase for current earth models such as S20RTS and S40RTS, FRT's phase errors are smaller, notably for the shortest wave periods considered (T ˜ 45 s and

  12. The effect of heterogeneity and surface roughness on soil hydrophobicity

    NASA Astrophysics Data System (ADS)

    Hallin, I.; Bryant, R.; Doerr, S. H.; Douglas, P.

    2010-05-01

    Soil water repellency, or hydrophobicity, can develop under both natural and anthropogenic conditions. Forest fires, vegetation decomposition, microbial activity and oil spills can all promote hydrophobic behaviour in surrounding soils. Hydrophobicity can stabilize soil organic matter pools and decrease evapotranspiration, but there are many negative impacts of hydrophobicity as well: increased erosion of topsoil, an increasingly scarce resource; increased runoff, which can lead to flooding; and decreased infiltration, which directly affects plant health. The degree of hydrophobicity expressed by soil can vary greatly within a small area, depending partly on the type and severity of the disturbance as well as on temporal factors such as water content and microbial activity. To date, many laboratory investigations into soil hydrophobicity have focused on smooth particle surfaces. As a result, our understanding of how hydrophobicity develops on rough surfaces of macro, micro and nano-particulates is limited; we are unable to predict with certainty how these soil particles will behave on contact with water. Surface chemistry is the main consideration when predicting hydrophobic behaviour of smooth solids, but for particles with rough surfaces, hydrophobicity is believed to develop as a combination of surface chemistry and topography. Topography may reflect both the arrangement (aggregation) of soil particles and the distribution of materials adsorbed on particulate surfaces. Patch-wise or complete coverage of rough soil particles by hydrophobic material may result in solid/water contact angles ≥150° , at which point the soil may be classified as super-hydrophobic. Here we present a critical review of the research to date on the effects of heterogeneity and surface roughness on soil hydrophobicity in which we discuss recent advances, current trends, and future research areas. References: Callies, M., Y. Chen, F. Marty, A. Pépin and D. Quéré. 2005. Microfabricated

  13. The interaction of surfaces across rough, metal-containing interfaces

    NASA Astrophysics Data System (ADS)

    Knarr, Randolph Frederick

    1999-10-01

    This thesis probes the interfacial and contact mechanical behavior between an optically smooth (nanometer-scale roughness) metal surface and an opposing surface of either a similar metal or a molecularly smooth mica surface (sub-Angstrom-scale roughness). This was carried out in a surface forces apparatus (SFA) equipped with extended spectral analysis of multiple beam interferometry (ESA-MBI) allowing Angstrom-scale deformations at the interface to be probed. During this work the SFA was enhanced to include an electrical resistance probe. The contact mechanics theory of Johnson, Kendall, and Roberts (JKR), 1971, originally developed for smooth, elastic bodies, is applied in broad new ways to describe the contact mechanical behavior of rough-metal contacts. The effects of depositing a self assembled monolayer (SAM) on one or both metal surfaces were also investigated. Finally, three new metals were introduced successfully into the SFA with the aid of optical theory to define the geometry of the metal films. In the JKR theory, the fundamental work of adhesion, W, is replaced with an effective work of adhesion that is shown to correlate with asperity deformations at the interface both in the loading and unloading cycles. For the case of metal-metal contact cold welding is observed and characterized. In the case of silver-silver contact, JKR theory is used to postulate that cold welding occurs in only a fraction of the whole contact zone. SAMs deposited on metals, gold in this case, are shown to inhibit cold welding in most cases and result in adequate description by JKR theory during unloading. Adhesion between SAM-coated metal surfaces correlates with terminal chemistry, with polar groups interacting more strongly. Optical theory was used to design experiments to successfully introduce three alternative metals into the SFA.

  14. Defining an optimal surface chemistry for pluripotent stem cell culture in 2D and 3D

    NASA Astrophysics Data System (ADS)

    Zonca, Michael R., Jr.

    Surface chemistry is critical for growing pluripotent stem cells in an undifferentiated state. There is great potential to engineer the surface chemistry at the nanoscale level to regulate stem cell adhesion. However, the challenge is to identify the optimal surface chemistry of the substrata for ES cell attachment and maintenance. Using a high-throughput polymerization and screening platform, a chemically defined, synthetic polymer grafted coating that supports strong attachment and high expansion capacity of pluripotent stem cells has been discovered using mouse embryonic stem (ES) cells as a model system. This optimal substrate, N-[3-(Dimethylamino)propyl] methacrylamide (DMAPMA) that is grafted on 2D synthetic poly(ether sulfone) (PES) membrane, sustains the self-renewal of ES cells (up to 7 passages). DMAPMA supports cell attachment of ES cells through integrin beta1 in a RGD-independent manner and is similar to another recently reported polymer surface. Next, DMAPMA has been able to be transferred to 3D by grafting to synthetic, polymeric, PES fibrous matrices through both photo-induced and plasma-induced polymerization. These 3D modified fibers exhibited higher cell proliferation and greater expression of pluripotency markers of mouse ES cells than 2D PES membranes. Our results indicated that desirable surfaces in 2D can be scaled to 3D and that both surface chemistry and structural dimension strongly influence the growth and differentiation of pluripotent stem cells. Lastly, the feasibility of incorporating DMAPMA into a widely used natural polymer, alginate, has been tested. Novel adhesive alginate hydrogels have been successfully synthesized by either direct polymerization of DMAPMA and methacrylic acid blended with alginate, or photo-induced DMAPMA polymerization on alginate nanofibrous hydrogels. In particular, DMAPMA-coated alginate hydrogels support strong ES cell attachment, exhibiting a concentration dependency of DMAPMA. This research provides a

  15. The use of new index for surface roughness of vegetation

    NASA Astrophysics Data System (ADS)

    Konda, Asako; Yamamoto, Hirokazu; Kajiwara, Koji; Honda, Yoshiaki

    2005-01-01

    Propose of a new Vegetation Index is purposes. Ordinal vegetation Index can show intensity of vegetation on the ground. It can not show structure of vegetation surface or texture. Proposed vegetation index utilizes BRF property. It is generated from data from 2 orbit of satellite and be able to show structure of vegetation surface or texture. Principles of this index is coming from field observation using RC helicopter. Each vegetation canopy has different texture and roughness. New index, named BSI (Bi-directional reflectance Structure Index) shows difference of vegetation canopy. It is calculated by using the data of NOAA/AVHRR, ADEOS OCTS. ADEOS-II GLI can derive BSI.

  16. Surface states in a 3D topological insulator: The role of hexagonal warping and curvature

    SciTech Connect

    Repin, E. V.; Burmistrov, I. S.

    2015-09-15

    We explore a combined effect of hexagonal warping and a finite effective mass on both the tunneling density of electronic surface states and the structure of Landau levels of 3D topological insulators. We find the increasing warping to transform the square-root van Hove singularity into a logarithmic one. For moderate warping, an additional logarithmic singularity and a jump in the tunneling density of surface states appear. By combining the perturbation theory and the WKB approximation, we calculate the Landau levels in the presence of hexagonal warping. We predict that due to the degeneracy removal, the evolution of Landau levels in the magnetic field is drastically modified.

  17. Surface processes on the asteroid deduced from the external 3D shapes and surface features of Itokawa particles

    NASA Astrophysics Data System (ADS)

    Tsuchiyama, A.; Matsumoto, T.

    2015-10-01

    Particles on the surface of S-type Asteroid 25143 Itokawa were successfully recovered by the Hayabusa mission of JAXA (e.g., [1,2]). They are not only the first samples recovered from an asteroid, but also the second extraterrestrial regolith to have been sampled, the first being the Moon by Apollo and Luna missions. The analysis of tiny sample particles (20-200 μm) shows that the Itokawa surface material is consistent with LL chondrites suffered by space weathering as expected and brought an end to the origin of meteorites (e.g., [2-4]). In addition, the examination of Itokawa particles allow studies of surface processes on the asteroid because regolith particles can be regarded as an interface with the space environment, where the impacts of small objects and irradiation by the solar wind and galactic cosmic rays should have been recorded. External 3D shapes and surface features of Itokawa regolith particles were examined. Two kinds of surface modification, formation of space-weathering rims mainly by solar wind implantation and surface abrasion by grain migration, were recognized. Spectral change of the asteroid proceeded by formation of space-weathering rims and refreshment of the regolith surfaces. External 3D shapes and surface morphologies of the regolith particles can provide information about formation and evolution history of regolith particles in relation to asteroidal surface processes. 3D shapes of Itokawa regolith particles were obtained using microtomography [3]. The surface nanomiromorpholgy of Itokawa particles were also observed using FE-SEM [5]. However, the number of particles was limited and genial feature on the surface morphology has not been understood. In this study, the surface morphology of Itokawa regolith particles was systematically investigated together with their 3D structures.

  18. Surface strain-field determination of tympanic membrane using 3D-digital holographic interferometry

    NASA Astrophysics Data System (ADS)

    Hernandez-Montes, María del S.; Mendoza Santoyo, Fernando; Muñoz, Silvino; Perez, Carlos; de la Torre, Manuel; Flores, Mauricio; Alvarez, Luis

    2015-08-01

    In order to increase the understanding of soft tissues mechanical properties, 3D Digital Holographic Interferometry (3D-DHI) was used to quantify the strain-field on a cat tympanic membrane (TM) surface. The experiments were carried out applying a constant sound-stimuli pressure of 90 dB SPL (0.632 Pa) on the TM at 1.2 kHz. The technique allows the accurate acquisition of the micro-displacement data along the x, y and z directions, which is a must for a full characterization of the tissue mechanical behavior under load, and for the calculation of the strain-field in situ. The displacements repeatability in z direction shows a standard deviation of 0.062 μm at 95% confidence level. In order to realize the full 3D characterization correctly the contour of the TM surface was measured employing the optically non-contact two-illumination positions contouring method. The x, y and z displacements combined with the TM contour data allow the evaluation its strain-field by spatially differentiating the u(m,n), v(m,n), and w(m,n) deformation components. The accurate and correct determination of the TM strain-field leads to describing its elasticity, which is an important parameter needed to improve ear biomechanics studies, audition processes and TM mobility in both experimental measurements and theoretical analysis of ear functionality and its modeling.

  19. SU-E-J-128: 3D Surface Reconstruction of a Patient Using Epipolar Geometry

    SciTech Connect

    Kotoku, J; Nakabayashi, S; Kumagai, S; Ishibashi, T; Kobayashi, T; Haga, A; Saotome, N; Arai, N

    2014-06-01

    Purpose: To obtain a 3D surface data of a patient in a non-invasive way can substantially reduce the effort for the registration of patient in radiation therapy. To achieve this goal, we introduced the multiple view stereo technique, which is known to be used in a 'photo tourism' on the internet. Methods: 70 Images were taken with a digital single-lens reflex camera from different angles and positions. The camera positions and angles were inferred later in the reconstruction step. A sparse 3D reconstruction model was locating by SIFT features, which is robust for rotation and shift variance, in each image. We then found a set of correspondences between pairs of images by computing the fundamental matrix using the eight-point algorithm with RANSAC. After the pair matching, we optimized the parameter including camera positions to minimize the reprojection error by use of bundle adjustment technique (non-linear optimization). As a final step, we performed dense reconstruction and associate a color with each point using the library of PMVS. Results: Surface data were reconstructed well by visual inspection. The human skin is reconstructed well, althogh the reconstruction was time-consuming for direct use in daily clinical practice. Conclusion: 3D reconstruction using multi view stereo geometry is a promising tool for reducing the effort of patient setup. This work was supported by JSPS KAKENHI(25861128)

  20. Large-area fabrication of 3D petal-like nanopattern for surface enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Zhou, Weimin; Wang, Jinhe; Zhang, Jing; Li, Xiaoli; Min, Guoquan

    2014-06-01

    A very easy and flexible approach to fabricate large area, petal-like nanopattern for surface enhanced Raman scattering using soft imprint lithography are presented here. The morphology of the petal-like nanopattern can be transferred truly using the h-PDMS and diluted PMMA molding template. By means of Au metal deposition, a SERS substrate with high enhancement factor over large area, which is still a problem, was produced easily. The morphology and Raman enhancement effect of the 3D nanopattern are characterized by SEM, AFM and SERS. The results show that the petal-like 3D nanopattern has high SERS enhancement factor (order of 1.0 × 108) and could be a promising low cost and high performance SERS active substrate.

  1. A fast method to measure the 3D surface of the human heart

    NASA Astrophysics Data System (ADS)

    Cao, Yiping; Su, Xianyu; Xiang, Liqun; Chen, Wenjing; Zhang, Qican

    2003-12-01

    Three-dimensional (3-D) automatic measurement of an object is widely used in many fields. In Biology and Medicine society, it can be applicable for surgery, orthopedics, viscera disease analysis and diagnosis etc. Here a new fast method to measure the 3D surface of human heart is proposed which can provide doctors a lot of information, such as the size of heart profile, the sizes of the left or right heart ventricle, and the curvature center and radius of heart ventricle, to fully analyze and diagnose pathobiology of human heart. The new fast method is optically and noncontacted and based upon the Phase Measurement Profilometry (PMP), which has higher measuring precision. A human heart specimen experiment has verified our method.

  2. An improved 3D shape context registration method for non-rigid surface registration

    NASA Astrophysics Data System (ADS)

    Xiao, Di; Zahra, David; Bourgeat, Pierrick; Berghofer, Paula; Acosta Tamayo, Oscar; Wimberley, Catriona; Gregoire, Marie-Claude; Salvado, Olivier

    2010-03-01

    3D shape context is a method to define matching points between similar shapes as a pre-processing step to non-rigid registration. The main limitation of the approach is point mismatching, which includes long geodesic distance mismatch and neighbors crossing mismatch. In this paper, we propose a topological structure verification method to correct the long geodesic distance mismatch and a correspondence field smoothing method to correct the neighbors crossing mismatch. A robust 3D shape context model is proposed and further combined with thin-plate spline model for non-rigid surface registration. The method was tested on phantoms and rat hind limb skeletons from micro CT images. The results from experiments on mouse hind limb skeletons indicate that the approach is robust.

  3. Rough spacecraft surfaces -a threat to Planetary Protection issues

    NASA Astrophysics Data System (ADS)

    Probst, Alexander; Facius, Rainer; Wirth, Reinhard; Moissl-Eichinger, Christine

    Inadvertent introduction of terrestrial microorganisms to foreign solar bodies could compromise the integrity of present and future life detection missions. For Planetary Protection purposes space agencies measure the aerobic, mesophilic spore load of a spacecraft as a proxy indicator in order to determine its bioload. Emerging novel hardware in space science implicates novel surface structures and materials that need to be controlled with regard to contaminations. For instance (roughened) carbon fiber reinforced plastic and Vectran fabric for construction of landing platforms and airbags, respectively, have been used in some Mars exploration missions. These materials have different levels of roughness and their potential risk to retain spores for insufficient sampling success has never been in scope of investigation. In this comprehensive study we evaluated ESA's novel nylon flocked swab protocol on stainless steel and other tech-nical surfaces with regard to Bacillus spore recovery. Low recovery efficiencies of the ESA standard wipe assay for large surface sampling were demonstrated with regard to Bacillus at-rophaeus spore detection. Therefore another protocol designed for rough surface sampling was evaluated on Vectran fabric and (roughened) carbon fiber reinforced plastic. Moreover, scan-ning electron micrographs of the technical surfaces studied allowed a more detailed view on their properties. The evaluated sampling protocols and the corresponding results are of high interest for future life detection missions in order to preserve their scientific integrity throughout spacecraft assembly.

  4. Maximum likelihood estimation of parameterized 3-D surfaces using a moving camera

    NASA Technical Reports Server (NTRS)

    Hung, Y.; Cernuschi-Frias, B.; Cooper, D. B.

    1987-01-01

    A new approach is introduced to estimating object surfaces in three-dimensional space from a sequence of images. A surface of interest here is modeled as a 3-D function known up to the values of a few parameters. The approach will work with any parameterization. However, in work to date researchers have modeled objects as patches of spheres, cylinders, and planes - primitive objects. These primitive surfaces are special cases of 3-D quadric surfaces. Primitive surface estimation is treated as the general problem of maximum likelihood parameter estimation based on two or more functionally related data sets. In the present case, these data sets constitute a sequence of images taken at different locations and orientations. A simple geometric explanation is given for the estimation algorithm. Though various techniques can be used to implement this nonlinear estimation, researches discuss the use of gradient descent. Experiments are run and discussed for the case of a sphere of unknown location. These experiments graphically illustrate the various advantages of using as many images as possible in the estimation and of distributing camera positions from first to last over as large a baseline as possible. Researchers introduce the use of asymptotic Bayesian approximations in order to summarize the useful information in a sequence of images, thereby drastically reducing both the storage and amount of processing required.

  5. Damage and deterioration monitoring of artwork by data fusion of 3D surface and hyperspectral measurements

    NASA Astrophysics Data System (ADS)

    Groves, Roger M.; Caballero, José; Quinzan, Ianisse; Ribes-Gómez, Emilio

    2014-05-01

    This paper describes the processing algorithm methodology and preliminary results from a novel optical-based system for the assessment of chemical and mechanical deterioration of artworks. The FP7 Syddarta Project prototype is composed of two optical channels: 1) a 3D imaging channel which acquires 3D surface data and multiband information in the visible spectral range; 2) an infrared hyperspectral imaging channel in the spectral range 900 to 2500 nm. The processing algorithms developed perform the system calibration, damage detection and chemical deterioration analysis. Both photometric and geometric calibrations have been implemented. The photometric calibration is based on a white reference and intensity map and compensates for variation in light intensities. The geometric calibration is based on planar homographies to determine the interior and exterior orientation of the projector and the two cameras. This is used to map the acquired data of the different sensors into a single reference frame. To acquire 3D data, a set of phase-shifted fringe patterns is projected on the object which are processed by Fourier transform. To identify mechanical deterioration, the acquired 3D cloud of points is meshed and differences in surface normals for a given radius are computed. To analyse the chemical deterioration of the pigments a supervised classification method has been implemented. First of all, spectral data is normalized with the Extended Multiplicative Scatter Correction algorithm. Then, data dimensionality is reduced by applying Principal Component Analysis and classification is done with Support Vector Machine. Results are presented showing the performance of the described algorithms.

  6. Impact of Surface Roughness on Capillary Trapping Using 2D-Micromodel Visualization Experiments

    NASA Astrophysics Data System (ADS)

    Geistlinger, Helmut; Attaei-Dadavi, Iman; Vogel, Hans-Jörg

    2016-04-01

    According to experimental observations, capillary trapping is strongly dependent on the roughness of the pore-solid interface. We performed imbibition experiments in the range of capillary numbers (Ca) from 10^-6 to 5x10^-5 using 2D-micromodels, which exhibit a rough surface. The microstructure comprises a double-porosity structure with pronounced macropores. The dynamics of precursor thin-film flow and its importance for capillary trapping is studied. For the first time Thin-Film Dynamics and the Complex Interplay of Thin Film- and Corner Flow for Snap-off Trapping is visualized using fluorescence microscopy. The experimental data for thin-film flow advancement show a square-root time dependence. Contrary to smooth surfaces, we prove by strict thermodynamical arguments that complete wetting is possible in a broad range of contact angles (0 - 90°). We develop a pore-scale model, which describes the front dynamics of thin-film flow on rough surfaces. Furthermore, contact angle hysteresis is considered for rough surfaces. We conduct a comprehensive cluster analysis, studying the influence of viscous forces (capillary number) and buoyancy forces (bond number) on cluster size distribution and comparing the results with predictions from percolation theory. We found that our experimental results agree with theoretical results of percolation theory for Ca = 10^-6: (i) a universal power-like cluster size distribution, (ii) the linear surface-volume relationship of trapped clusters, and (iii) the existence of the cut-off correlation length for the maximal cluster height. The good agreement is a strong argument that the experimental cluster size distribution is caused by a percolation-like trapping process (Ordinary Percolation). [1] H. Geistlinger, I. Ataei-Dadavi, S. Mohammadian, and H.-J. Vogel (2015) The Impact of Pore structure and Surface Roughness on Capillary Trapping for 2D- and 3D-porous media: Comparison with Percolation theory. Special issue: Applications of

  7. A theoretical analysis of sliding of rough surfaces

    NASA Astrophysics Data System (ADS)

    Walsh, J. B.

    2003-08-01

    I used a model proposed by [1966], who analyzed closure between a rough surface and a smooth surface under normal stress, to analyze the growth of slip under increasing shear stress, normal stress remaining constant. The two bodies are elastic half-spaces, one rough and one smooth, and Coulomb friction resists slip at sliding contacts. The elastic and dissipative components of the constitutive relation in shear depend upon statistical parameters which describe the topography of the rough surface. I made a parametric study of the effect of topography on the constitutive relations in shear by comparing a model in which the progress of slip at a contact is continuous with one in which the contact goes discontinuously from "stuck" to sliding. The effect of topography was also studied by assuming that the probability density distribution of the heights of asperities is Gaussian or, alternatively, a negative exponential. These variations in topography produced only minor differences in the constitutive behavior. This insensitivity of the constitutive behavior to differences in the statistical description of the topography arises in part because, only relatively, a small range of asperity heights is active in typical experiments. Work done against friction introduces a dissipative component into the constitutive behavior which I evaluated analytically; I show that the components have a simple graphical construction on plots of shear stress versus displacement developed from experimental observations. Sliding in the reverse sense which occurs when the applied shear stress is relaxed is analyzed, resulting in expressions which describe the shape of hysteresis loops formed when shear stress is cycled. Introducing measurements made on surfaces of specimens of granite and quartzite into the theoretical relations, I found reasonable agreement with experimental data.

  8. 3-D Measurement and Visualization of Electrical Propagation on Heart Surface

    NASA Astrophysics Data System (ADS)

    Lin, Shien-Fong; Wikswo, John P.

    1997-11-01

    Optical recording of the cardiac transmembrane potential (Vm) has recently become a powerful tool to reveal patterns of electrical wave front dynamics on the heart surface. The optical mapping techniques have been previously applied to observe a portion of the heart due to its 3-D geometry. We extended our 2-D optical mapping technique to include one front view and two back mirror views for measuring and visualizing the transmembrane potential distribution simultaneously over entire surface of an isolated rabbit heart. The heart was illuminated with an argon laser delivered through an optical fiber bundle consisting of seven 1-mm fibers. These fibers were positioned around the heart to induce a near-uniform fluorescence intensity distribution on the heart surface. A single high-speed CCD camera with a long depth of field recorded the laser-stimulated epifluorescence from all three views in a single frame. Sequences of 100 to 600 frames of 12-bit/pixel digital images were recorded during regular pacing or induced ventricular fibrillation at 335 frames/second. Image processing then yielded the Vm distribution at a resolution of 128x64 pixels/frame. The propagating wave front images were obtained by subtracting two subsequent Vm images. The geometry of the heart was obtained by profilometry. The wave front information obtained from image processing could be texture-mapped to the heart geometry for visualization. Our 3-D imaging technique provides simultaneous, dynamic information of wave front activation and propagation over entire heart surface, and thereby can offer a more complete knowledge of wave front dynamics in a whole heart model. Future work involves automatic procedure for digitizing the heart shape and measuring the wave front dimensions using the 3-D geometry.

  9. Parameterized code SHARM-3D for radiative transfer over inhomogeneous surfaces

    NASA Astrophysics Data System (ADS)

    Lyapustin, Alexei; Wang, Yujie

    2005-12-01

    The code SHARM-3D, developed for fast and accurate simulations of the monochromatic radiance at the top of the atmosphere over spatially variable surfaces with Lambertian or anisotropic reflectance, is described. The atmosphere is assumed to be laterally uniform across the image and to consist of two layers with aerosols contained in the bottom layer. The SHARM-3D code performs simultaneous calculations for all specified incidence-view geometries and multiple wavelengths in one run. The numerical efficiency of the current version of code is close to its potential limit and is achieved by means of two innovations. The first is the development of a comprehensive precomputed lookup table of the three-dimensional atmospheric optical transfer function for various atmospheric conditions. The second is the use of a linear kernel model of the land surface bidirectional reflectance factor (BRF) in our algorithm that has led to a fully parameterized solution in terms of the surface BRF parameters. The code is also able to model inland lakes and rivers. The water pixels are described with the Nakajima-Tanaka BRF model of wind-roughened water surface with a Lambertian offset, which is designed to model approximately the reflectance of suspended matter and of a shallow lake or river bottom.

  10. Diaphragm dome surface segmentation in CT data sets: a 3D active appearance model approach

    NASA Astrophysics Data System (ADS)

    Beichel, Reinhard; Gotschuli, Georg; Sorantin, Erich; Leberl, Franz W.; Sonka, Milan

    2002-05-01

    Knowledge about the location of the diaphragm dome surface, which separates the lungs and the heart from the abdominal cavity, is of vital importance for applications like automated segmentation of adjacent organs (e.g., liver) or functional analysis of the respiratory cycle. We present a new 3D Active Appearance Model (AAM) approach to segmentation of the top layer of the diaphragm dome. The 3D AAM consists of three parts: a 2D closed curve (reference curve), an elevation image and texture layers. The first two parts combined represent 3D shape information and the third part image intensity of the diaphragm dome and the surrounding layers. Differences in height between dome voxels and a reference plane are stored in the elevation image. The reference curve is generated by a parallel projection of the diaphragm dome outline in the axial direction. Landmark point placement is only done on the (2D) reference curve, which can be seen as the bounding curve of the elevation image. Matching is based on a gradient-descent optimization process and uses image intensity appearance around the actual dome shape. Results achieved in 60 computer generated phantom data sets show a high degree of accuracy (positioning error -0.07+/-1.29 mm). Validation using real CT data sets yielded a positioning error of -0.16+/-2.95 mm. Additional training and testing on in-vivo CT image data is ongoing.

  11. Cement paste surface roughness analysis using coherence scanning interferometry and confocal microscopy

    SciTech Connect

    Apedo, K.L.; Munzer, C.; He, H.; Montgomery, P.; Serres, N.; Fond, C.; Feugeas, F.

    2015-02-15

    Scanning electron microscopy and scanning probe microscopy have been used for several decades to better understand the microstructure of cementitious materials. Very limited work has been performed to date to study the roughness of cementitious materials by optical microscopy such as coherence scanning interferometry (CSI) and chromatic confocal sensing (CCS). The objective of this paper is to better understand how CSI can be used as a tool to analyze surface roughness and topography of cement pastes. Observations from a series of images acquired using this technique on both polished and unpolished samples are described. The results from CSI are compared with those from a STIL confocal microscopy technique (SCM). Comparison between both optical techniques demonstrates the ability of CSI to measure both polished and unpolished cement pastes. - Highlights: • Coherence scanning interferometry (CSI) was used to analyze cement paste surfaces. • The results from the CSI were compared with those from a confocal microscopy. • 3D roughness parameters were obtained using the window resizing method. • Polished and unpolished cement pastes were studied.

  12. TRAIL protein localization in human primary T cells by 3D microscopy using 3D interactive surface plot: a new method to visualize plasma membrane.

    PubMed

    Gras, Christophe; Smith, Nikaïa; Sengmanivong, Lucie; Gandini, Mariana; Kubelka, Claire Fernandes; Herbeuval, Jean-Philippe

    2013-01-31

    The apoptotic ligand TNF-related apoptosis ligand (TRAIL) is expressed on the membrane of immune cells during HIV infection. The intracellular stockade of TRAIL in human primary CD4(+) T cells is not known. Here we investigated whether primary CD4(+) T cells expressed TRAIL in their intracellular compartment and whether TRAIL is relocalized on the plasma membrane under HIV activation. We found that TRAIL protein was stocked in intracellular compartment in non activated CD4(+) T cells and that the total level of TRAIL protein was not increased under HIV-1 stimulation. However, TRAIL was massively relocalized on plasma membrane when cells were cultured with HIV. Using three dimensional (3D) microscopy we localized TRAIL protein in human T cells and developed a new method to visualize plasma membrane without the need of a membrane marker. This method used the 3D interactive surface plot and bright light acquired images. PMID:23085529

  13. Characterising glacier-wide ice-surface roughness using a combined Structure-from-Motion and Terrestrial Laser Scanning approach

    NASA Astrophysics Data System (ADS)

    Quincey, D. J.; Smith, M. W.; Carrivick, J. L.; Rippin, D. M.; Bingham, R. G.

    2015-12-01

    Ice-surface roughness is a poorly parameterised component of most surface energy balance models, often being represented by a single constant value, or effective roughness length. Yet it plays an important role in determining sensible heat flux, which may contribute ~30% to the overall surface energy balance at high-latitudes. Measurements of ice-surface roughness have thus far been dominated by microtopographic and one-dimensional profile-based approaches, which generate rather crude assessments of roughness length. The availability of fine-resolution and multi-temporal topographic datasets offers an opportunity to develop more robust methods. Using a combined Structure-from-Motion (SfM) and Terrestrial Laser Scanning (TLS) approach, we demonstrate that glacier-wide surface roughness can be characterised over multiple time periods, meaning sensible heat transfer can be much better parameterised in energy balance modelling. Here we present fine-scale topographic data from 30 plots, each measuring 2 m x 2 m, acquired on Kårsaglaciären, Northern Sweden over a period of four days. Glacier surface types included smooth/superimposed ice, runnels, cryoconite, sun cusps, blocky crystalline ice, supraglacial channels, dirty ice, light/medium/dense scree-covered ice, shallow/deep crevasses and snow. We test multiple methods for extracting z0 and demonstrate a novel 3D approach that uses the dense point cloud rather than a decimated (2D) product. Z0 is shown to vary widely over different surface types, with values ranging over more than an order of magnitude. The evolution of surface roughness is also shown to vary with surface type, with some plots becoming rougher and others becoming smoother through time. Finally, we use a glacier-wide DEM generated from TLS to correlate the detrended standard deviation of elevations in each plot with the calculated z0 values and thus produce a glacier-wide characterisation of ice-surface roughness.

  14. Roughness of human enamel surface submitted to different prophylaxis methods.

    PubMed

    Castanho, Gisela Muassab; Arana-Chavez, Victor E; Fava, Marcelo

    2008-01-01

    The purpose of this in vitro study was to evaluate alterations in the surface roughness and micromorphology of human enamel submitted to three prophylaxis methods. Sixty-nine caries-free molars with exposed labial surfaces were divided into three groups. Group I was treated with a rotary instrument set at a low speed, rubber cup and a mixture of water and pumice; group II with a rotary instrument set at a low speed, rubber cup and prophylaxis paste Herjos-F (Vigodent S/A Indústria e Comércio, Rio de Janeiro, Brazil); and group III with sodium bicarbonate spray Profi II Ceramic (Dabi Atlante Indústrias Médico Odontológicas Ltda, Ribeirão Preto, Brazil). All procedures were performed by the same operator for 10 s, and samples were rinsed and stored in distilled water Pre and post-treatment surface evaluation was completed using a surface profilometer (Perthometer S8P, Marh, Perthen, Germany) in 54 samples. In addition, the other samples were coated with gold and examined in a scanning electron microscope (SEM). The results of this study were statistically analyzed with the paired t-test (Student), the Kruskal-Wallis test and the Dunn (5%) test. The sodium bicarbonate spray led to significantly rougher surfaces than the pumice paste. The use of prophylaxis paste showed no statistically significant difference when compared with the other methods. Based on SEM analysis, the sodium bicarbonate spray presented an irregular surface with granular material and erosions. Based on this study, it can be concluded that there was an increased enamel surface roughness when teeth were treated with sodium bicarbonate spray when compared with teeth treated with pumice paste. PMID:18767461

  15. Anomalous surface segregation behaviour of some 3d elements in ferromagnetic iron.

    PubMed

    Gupta, Michèle; Gupta, Raju P

    2013-10-16

    The segregation of Cr in Fe is known to be anomalous since the barrier for surface segregation of Cr is not determined by the topmost surface layer, as one would expect, but rather by the subsurface layer where the energy of segregation is much larger and endothermic. This has been attributed to a complex interaction involving the antiferromagnetism of Cr and the ferromagnetism of Fe. We report in this paper the results of our ab initio electronic structure calculations on the segregation behaviour of all the 3d elements on the (1 0 0) surface of ferromagnetic iron in the hope of better understanding this phenomenon. We find a similar behaviour for the segregation of the next antiferromagnetic 3d element Mn in Fe, where the subsurface layer is also found to block the segregation of Mn to the surface. On the other hand, ferromagnetic Co exhibits a normal segregation behaviour. The elements Sc, Cu and Ni do not form solid solutions with ferromagnetic iron. The early elements Ti and V are non-magnetic in their metallic states, but are strongly polarized by Fe, and develop magnetic moments which are aligned antiferromagnetically to those of Fe atoms. While the subsurface layer blocks the segregation of Ti to the surface, no blocking behaviour is found for the segregation of V. The segregation behaviour of all these elements is strongly correlated with the displacement of the solute atoms on the surface of Fe. The elements showing anomalous segregation behaviour are all displaced upwards on the surface, while those showing normal segregation are pulled inwards. These results indicate that the antiferromagnetism of the segregating element plays the key role in the anomalous segregation behaviour in Fe. PMID:24047767

  16. Multiscale roughness analysis of engineering surfaces: A comparison of methods for the investigation of functional correlations

    NASA Astrophysics Data System (ADS)

    Goïc, Gaëtan Le; Bigerelle, Maxence; Samper, Serge; Favrelière, Hugues; Pillet, Maurice

    2016-01-01

    This study investigates the correlations between the topography of different damaged rough surfaces and process conditions. Several surfaces are measured and compared to determine if they can be discriminated. The analysis is performed by using Gaussian Filtering, Wavelet Transform and a more recent approach named Discrete Modal Decomposition. Standardized 3D roughness parameters are computed for each multiscale method, filter (e.g., high-pass, low-pass and band-pass) and available scale. The relevance (i.e., the ability to discriminate surface topographies corresponding to different process conditions) is then investigated using a statistical analysis based on the MesRugTM expert system. The results indicate clear differences between the multiscale methods and show that the Wavelet approach is useful when characterizing localized surface defects while Gaussian Filtering is more appropriate for highly periodic morphological structures. For more complex topographies, this study also clearly shows that the Discrete Modal Decomposition exhibits compelling abilities that fall between those of the Gaussian and Wavelet approaches; this method is clearly more relevant than the Gaussian method in the case of localized defects and less relevant in the case of highly periodical structures and fractal surfaces (1 /fα spectrum). This can be explained by the modulated frequency/amplitude descriptors generated via the modal basis.

  17. Performance analysis of different surface reconstruction algorithms for 3D reconstruction of outdoor objects from their digital images.

    PubMed

    Maiti, Abhik; Chakravarty, Debashish

    2016-01-01

    3D reconstruction of geo-objects from their digital images is a time-efficient and convenient way of studying the structural features of the object being modelled. This paper presents a 3D reconstruction methodology which can be used to generate photo-realistic 3D watertight surface of different irregular shaped objects, from digital image sequences of the objects. The 3D reconstruction approach described here is robust, simplistic and can be readily used in reconstructing watertight 3D surface of any object from its digital image sequence. Here, digital images of different objects are used to build sparse, followed by dense 3D point clouds of the objects. These image-obtained point clouds are then used for generation of photo-realistic 3D surfaces, using different surface reconstruction algorithms such as Poisson reconstruction and Ball-pivoting algorithm. Different control parameters of these algorithms are identified, which affect the quality and computation time of the reconstructed 3D surface. The effects of these control parameters in generation of 3D surface from point clouds of different density are studied. It is shown that the reconstructed surface quality of Poisson reconstruction depends on Samples per node (SN) significantly, greater SN values resulting in better quality surfaces. Also, the quality of the 3D surface generated using Ball-Pivoting algorithm is found to be highly depend upon Clustering radius and Angle threshold values. The results obtained from this study give the readers of the article a valuable insight into the effects of different control parameters on determining the reconstructed surface quality. PMID:27386376

  18. Observations of swell influence on ocean surface roughness

    NASA Astrophysics Data System (ADS)

    Hwang, Paul A.

    2008-12-01

    Field measurements of the ocean surface wave spectrum focusing on the slope-contributing components are used to construct a spectral model of the ocean surface roughness. The spectral parameterization is established with the observed empirical power law relation between the dimensionless wave spectral density and wind speed. The power law parameters (proportionality coefficient and exponent) are shown to be modified by swell. Discussions are presented on the swell effects of spectral properties, including their wind speed dependence and swell modification of roughness components characterizing Bragg resonance and surface tilting in radar application. Several notable results include the following: (1) With increasing swell intensity, the spectral density increases in the long-wave portion and decreases in the short-wave portion of the intermediate-scale waves. (2) There is a nodal point with respect to swell impact in the wave number dependence of the coefficient and exponent of the spectral parameterization function in the vicinity of wave number near 3 rad/m, suggesting that waves about a couple of meters long are insensitive to swell influence. (3) Spectral density in the decimeter length scale becomes less sensitive to wind speed variation as swell intensity increases. (4) Increasing swell influence shifts wave breaking toward shorter and broader scales.

  19. Influence of Surface Roughness in Electron Beam Welding

    NASA Astrophysics Data System (ADS)

    Wiednig, C.; Stiefler, F.; Enzinger, N.

    2016-03-01

    The requirements of welded components are rising continuously through increasing demands in engineering. But in engineering not only the quality of welds is important also an economic and timesaving production is crucial. Especially in welding of large cross sections economization potential is existing and significant. Beside the welding technique itself the joint preparation is a major part of work. Electron beam welding has some major advantages in this area. Due the high energy density a very short welding time as well as a small heat affected zone can be achieved. Furthermore the joint preparation can be held simple. Nevertheless, a careful machining and cleaning of the joint surfaces is recommended in literature. In addition to geometric tolerances a specific surface roughness should be kept. These statements are quite general and unspecific. In this contribution a systematic investigation on the influence of joint preparation on the joint properties is presented. By performing several welding experiments with different surface roughness this study provides empirical conclusions. Beside the microscopic investigation of different cross sections and mechanical tests of the welded samples also the process stability during welding was reviewed.

  20. Radar, visual and thermal characteristics of Mars - Rough planar surfaces

    NASA Technical Reports Server (NTRS)

    Schaber, G. G.

    1980-01-01

    High-resolution Viking Orbiter images contain significant information on Martian surface roughness at 25- to 100-m lateral scales, while earth-based radar observations of Mars are sensitive to roughness at lateral scales of 1 to 30 m or more. High-rms slopes predicted for the Tharsis-Memnonia-Amazonis volcanic plains from extremely weak radar returns are qualitatively confirmed by the Viking image data. Large-scale, curvilinear ridges on lava flows in the Memnonia Fossae region are interpreted as innate flow morphology caused by compressional foldover of moving lava sheets of possible rhyolite-dacite composition. The presence or absence of a recent mantle of fine-grained eolian material on the volcanic surfaces studied was determined by the visibility of fresh impact craters with diameters less than 50 m. Lava flows with surfaces modified by eolian erosion and deposition occur west-northwest of Apollinaris Patera at the border of the cratered equatorial uplands and southern Elysium Planitia. Nearby yardangs, for which radar observations indicate very high-rms slopes, are similar to terrestrial features of similar origin.

  1. Shot noise limit of the optical 3D measurement methods for smooth surfaces

    NASA Astrophysics Data System (ADS)

    Pavliček, Pavel; Pech, Miroslav

    2016-03-01

    The measurement uncertainty of optical 3D measurement methods for smooth surfaces caused by shot noise is investigated. The shot noise is a fundamental property of the quantum nature of light. If all noise sources are eliminated, the shot noise represents the ultimate limit of the measurement uncertainty. The measurement uncertainty is calculated for several simple model methods. The analysis shows that the measurement uncertainty depends on the wavelength of used light, the number of photons used for the measurement, and on a factor that is connected with the geometric arrangement of the measurement setup.

  2. Measuring Skew in Average Surface Roughness as a Function of Surface Preparation

    NASA Technical Reports Server (NTRS)

    Stahl, Mark T.

    2015-01-01

    Characterizing surface roughness is important for predicting optical performance. Better measurement of surface roughness reduces grinding saving both time and money and allows the science requirements to be better defined. In this study various materials are polished from a fine grind to a fine polish. Each sample's RMS surface roughness is measured at 81 locations in a 9x9 square grid using a Zygo white light interferometer at regular intervals during the polishing process. Each data set is fit with various standard distributions and tested for goodness of fit. We show that the skew in the RMS data changes as a function of polishing time.

  3. Extended volume and surface scatterometer for optical characterization of 3D-printed elements

    NASA Astrophysics Data System (ADS)

    Dannenberg, Florian; Uebeler, Denise; Weiß, Jürgen; Pescoller, Lukas; Weyer, Cornelia; Hahlweg, Cornelius

    2015-09-01

    The use of 3d printing technology seems to be a promising way for low cost prototyping, not only of mechanical, but also of optical components or systems. It is especially useful in applications where customized equipment repeatedly is subject to immediate destruction, as in experimental detonics and the like. Due to the nature of the 3D-printing process, there is a certain inner texture and therefore inhomogeneous optical behaviour to be taken into account, which also indicates mechanical anisotropy. Recent investigations are dedicated to quantification of optical properties of such printed bodies and derivation of corresponding optimization strategies for the printing process. Beside mounting, alignment and illumination means, also refractive and reflective elements are subject to investigation. The proposed measurement methods are based on an imaging nearfield scatterometer for combined volume and surface scatter measurements as proposed in previous papers. In continuation of last year's paper on the use of near field imaging, which basically is a reflective shadowgraph method, for characterization of glossy surfaces like printed matter or laminated material, further developments are discussed. The device has been extended for observation of photoelasticity effects and therefore homogeneity of polarization behaviour. A refined experimental set-up is introduced. Variation of plane of focus and incident angle are used for separation of various the images of the layers of the surface under test, cross and parallel polarization techniques are applied. Practical examples from current research studies are included.

  4. Mapping gray-scale image to 3D surface scanning data by ray tracing

    NASA Astrophysics Data System (ADS)

    Li, Peng; Jones, Peter R. M.

    1997-03-01

    The extraction and location of feature points from range imaging is an important but difficult task in machine vision based measurement systems. There exist some feature points which are not able to be detected from pure geometric characteristics, particularly in those measurement tasks related to the human body. The Loughborough Anthropometric Shadow Scanner (LASS) is a whole body surface scanner based on structured light technique. Certain applications of LASS require accurate location of anthropometric landmarks from the scanned data. This is sometimes impossible from existing raw data because some landmarks do not appear in the scanned data. Identification of these landmarks has to resort to surface texture of the scanned object. Modifications to LASS were made to allow gray-scale images to be captured before or after the object was scanned. Two-dimensional gray-scale image must be mapped to the scanned data to acquire the 3D coordinates of a landmark. The method to map 2D images to the scanned data is based on the colinearity conditions and ray-tracing method. If the camera center and image coordinates are known, the corresponding object point must lie on a ray starting from the camera center and connecting to the image coordinate. By intersecting the ray with the scanned surface of the object, the 3D coordinates of a point can be solved. Experimentation has demonstrated the feasibility of the method.

  5. 3D surface reconstruction and FIB microscopy of worn alumina hip prostheses

    NASA Astrophysics Data System (ADS)

    Zeng, P.; Inkson, B. J.; Rainforth, W. M.; Stewart, T.

    2008-08-01

    Interest in alumina-on-alumina total hip replacements (THR) continues to grow for the young and active patient due to their superior wear performance and biocompatibility compared to the alternative traditional polymer/metal prostheses. While alumina on alumina bearings offer an excellent solution, a region of high wear, known as stripe wear, is commonly observed on retrieved alumina hip components that poses concern. These in-vivo stripe wear mechanisms can be replicated in vitro by the introduction of micro-separation during the simulated walking cycle in hip joint simulation. However, the understanding of the mechanisms behind the stripe wear processes is relatively poor. 3D topographic reconstructions of titled SEM stereo pairs from different zones have been obtained to determine the local worn surface topography. Focused ion beam (FIB) microscopy was applied to examine the subsurface damage across the stripe wear. The paper presents novel images of sub-surface microcracks in alumina along with 3D reconstructions of the worn ceramic surfaces and a classification of four distinct wear zones following microseparation in hip prostheses.

  6. Underwater 3D Surface Measurement Using Fringe Projection Based Scanning Devices.

    PubMed

    Bräuer-Burchardt, Christian; Heinze, Matthias; Schmidt, Ingo; Kühmstedt, Peter; Notni, Gunther

    2015-01-01

    In this work we show the principle of optical 3D surface measurements based on the fringe projection technique for underwater applications. The challenges of underwater use of this technique are shown and discussed in comparison with the classical application. We describe an extended camera model which takes refraction effects into account as well as a proposal of an effective, low-effort calibration procedure for underwater optical stereo scanners. This calibration technique combines a classical air calibration based on the pinhole model with ray-based modeling and requires only a few underwater recordings of an object of known length and a planar surface. We demonstrate a new underwater 3D scanning device based on the fringe projection technique. It has a weight of about 10 kg and the maximal water depth for application of the scanner is 40 m. It covers an underwater measurement volume of 250 mm × 200 mm × 120 mm. The surface of the measurement objects is captured with a lateral resolution of 150 μm in a third of a second. Calibration evaluation results are presented and examples of first underwater measurements are given. PMID:26703624

  7. Underwater 3D Surface Measurement Using Fringe Projection Based Scanning Devices

    PubMed Central

    Bräuer-Burchardt, Christian; Heinze, Matthias; Schmidt, Ingo; Kühmstedt, Peter; Notni, Gunther

    2015-01-01

    In this work we show the principle of optical 3D surface measurements based on the fringe projection technique for underwater applications. The challenges of underwater use of this technique are shown and discussed in comparison with the classical application. We describe an extended camera model which takes refraction effects into account as well as a proposal of an effective, low-effort calibration procedure for underwater optical stereo scanners. This calibration technique combines a classical air calibration based on the pinhole model with ray-based modeling and requires only a few underwater recordings of an object of known length and a planar surface. We demonstrate a new underwater 3D scanning device based on the fringe projection technique. It has a weight of about 10 kg and the maximal water depth for application of the scanner is 40 m. It covers an underwater measurement volume of 250 mm × 200 mm × 120 mm. The surface of the measurement objects is captured with a lateral resolution of 150 μm in a third of a second. Calibration evaluation results are presented and examples of first underwater measurements are given. PMID:26703624

  8. The Turbulent Boundary Layer on a Rough Curvilinear Surface

    NASA Technical Reports Server (NTRS)

    Droblenkov, V. F.

    1958-01-01

    A number of semiempirical approximate methods exist for determining the characteristics of the turbulent boundary layer on a curvilinear surface. At present, among these methods, the one proposed by L. G. Loitsianskii is given frequent practical application. This method is sufficiently effective and permits, in the case of wing profiles with technically smooth surfaces, calculating the basic characteristics of the boundary layer and the values of the overall drag with an accuracy which suffices for practical purposes. The idea of making use of the basic integral momentum equation ((d delta(sup xx))/dx) + ((V' delta(sup xx))/V) (2 + H) = (tau(sub 0))/(rho V(exp 2)) proves to be fruitful also for the solution of the problems in the determination of the characteristics of the turbulent boundary layer on a rough surface.

  9. Grafting of alumina on SBA-15: effect of surface roughness.

    PubMed

    Zukal, A; Siklová, H; Cejka, J

    2008-09-01

    Alumina-grafted materials were prepared by postsynthesis alumination of mesoporous SBA-15 silica in an aqueous solution of aluminum chlorhydrol. Prepared samples were characterized by nitrogen adsorption, scanning electron microscopy, X-ray powder diffraction, and (27)Al magic-angle-spinning NMR. The successive grafting of alumina on SBA-15 leads to a gradual filling of the corona surrounding the mesopores. As a consequence smoothing of the mesopore surface takes place. The in-depth analysis of nitrogen adsorption data proves that the alpha s method affords real values of the structure parameters, while the Kruk, Jaroniec, and Sayari (KJS) procedure based on the BJH algorithm provides only effective data corresponding to cylindrical mesopores of smooth geometrical surface. The quantification of the roughness of the SBA-15 mesopore surface based on the comparison of data obtained from the alpha s plot and KJS method was carried out. PMID:18683961

  10. The effects of the substrate surface roughness on graphene plasmons

    SciTech Connect

    Lyon, Keenan A.; Miskovic, Zoran L.

    2014-03-31

    We investigate the effects of variation in the gap size between mono-layer graphene and a substrate with a randomly rough surface on the linear response of graphene’s π electron bands within the approximation of Dirac fermions. We adopt the electrostatic Green’s function developed by Rahman and Maradudin [Phys. Rev. B 21, 2137–2143 (1980)] for the surface of a dielectric medium, which exhibits a Gaussian distributed height profile and combine it with the polarization function of graphene described as a zero-thickness planar layer at a fixed distance from the mean position of the substrate surface. We specifically consider the effects of a random gap size on the two-dimensional sheet plasmon mode in heavily doped graphene, both on its dispersion relation in the long-wavelength limit and its broadening due to Landau damping in the continuum of inter-band electron-hole excitations at shorter wavelengths.

  11. Density functional study of hydrazine N-N bond cleaving on 3d metal surfaces

    NASA Astrophysics Data System (ADS)

    Fathurrahman, Fadjar; Kasai, Hideaki

    2015-11-01

    Theoretical calculations based on dispersion-corrected density functional theory (DFT-D2) has been performed to investigate hydrazine adsorption and N-N bond cleaving on closed packed surfaces of 3d metals: Fe(110), Co(0001), Ni(111), Cu(111), and Zn(0001). The activation energies of N-N bond cleaving of hydrazine on each surface are estimated using climbing-image nudged elastic band (CINEB) method. The results showed that the activation energies for this process have increasing trend from Fe(110) to Zn(0001). By examining the electronic structure of the adsorbed hydrazine, it is found that this trend is related to occupation of derived 6σ* orbitals. It is also found that approximate linear relationship between reaction energy and activation energy (the Brønsted-Evans-Polanyi (BEP) relationship) holds for those surfaces.

  12. Preliminary study of surface modification of 3D Poly (ɛ - caprolactone) scaffolds by ultrashort laser irradiation

    NASA Astrophysics Data System (ADS)

    Daskalova, A.; Bliznakova, I.; Iordanova, E.; Yankov, G.; Grozeva, M.; Ostrowska, B.

    2016-02-01

    Three - dimensional poly (e- caprolactone) (PCL) scaffolds as suitable biocompatible material for manufacturing tissue replacements are utilized for tissue engineering purposes. The porous structures are fabricated by rapid prototyping method (Bioscaffolder) based on hypodermic dispensing process. The consecution of experiments demonstrated the possibility on creation of surface micro formations, applying different laser fluences, at 1 kHz repetition rate for fixed time of exposure 1 sec at 800 nm central wavelength. The combination of both methods offers possibilities for successful production of 3D matrices with modified surfaces. The obtained results of laser - induced surface modifications of PCL demonstrate the potential of the method to microprocess this kind of material for possible applications in regenerative medicine.

  13. Effects of surface roughness on evaporation from porous surfaces into turbulent airflows

    NASA Astrophysics Data System (ADS)

    Haghighi, Erfan; Or, Dani

    2014-05-01

    The ubiquitous and energy intensive mass transfer between wet porous surfaces and turbulent airflows is of great importance for various natural and industrial applications. The roughness of natural surfaces is likely to influence the structure of adjacent boundary layer and thus affecting heat and mass fluxes from surfaces. These links were formalized in a new model that considers the intermittent turbulence-induced boundary layer with local mass and energy exchange rates. We conducted experiments with regular surface roughness patterns subjected to constant turbulent airflows and monitored mass loss and thermal signatures of localized evaporative fluxes using infrared thermography. The resulting patterns were in good agreement with model predictions for local and surface averaged turbulent exchange rates. Preliminary results obtained for evaporation from sinusoidal wavy soil surfaces reveal that evaporative fluxes can be either enhanced or suppressed (relative to a flat surface) owing to relative contribution of downstream (separation zone) and rising (reattachment zone) surfaces of the wave with thick and thin viscous sublayer thicknesses, respectively. For isolated roughness elements (bluff bodies) over a flat evaporating surface, the resulting fluxes are enhanced (relative to a smooth surface) due to formation of vortices that induce thinner boundary layer. Potential benefits of the study for interpretation and upscaling of evaporative and heat fluxes from natural (rough) terrestrial surfaces will be discussed. Keywords: Turbulent Evaporation, Porous Media, Surface Roughness, Infrared Thermography.

  14. Preparation of poly(L-lactic acid) nanofiber scaffolds with a rough surface by phase inversion using supercritical carbon dioxide.

    PubMed

    Yang, Ding-Zhu; Chen, Ai-Zheng; Wang, Shi-Bin; Li, Yi; Tang, Xiao-Lin; Wu, Yong-Jing

    2015-06-01

    Phase inversion using supercritical carbon dioxide (SC-CO2) has been widely used in the development of tissue engineering scaffolds, and particular attention has been given to obtaining desired morphology without additional post-treatments. However, the main challenge of this technique is the difficulty in generating a three-dimensional (3D) nanofiber structure with a rough surface in one step. Here, a poly(L-lactic acid) (PLLA) 3D nanofiber scaffold with a rough surface is obtained via phase inversion using SC-CO2 by carefully choosing fabrication conditions and porogens. It is found that this method can effectively modulate the structure morphology, promote the crystallization process of semicrystalline polymer, and induce the formation of rough structures on the surface of nanofibers. Meanwhile, the porogen of ammonium bicarbonate (AB) can produce a 3D structure with large pores, and porogen of menthol can improve the interconnectivity between the micropores of nanofibers. A significant increase in the fiber diameter is observed as the menthol content increases. Furthermore, the menthol may affect the mutual transition between the α' and α crystals of PLLA during the phase separation process. In addition, the results of protein adsorption, cell adhesion, and proliferation assays indicate that cells tend to have higher viability on the nanofiber scaffold. This process combines the characteristic properties of SC-CO2 and the solubility of menthol to tailor the morphology of polymeric scaffolds, which may have potential applications in tissue engineering. PMID:26107415

  15. Modeling of surface roughness: application to physical properties of paper

    NASA Astrophysics Data System (ADS)

    Bloch, Jean-Francis; Butel, Marc

    2000-09-01

    Papermaking process consists in a succession of unit operations having for main objective the expression of water out of the wet paper pad. The three main stages are successively, the forming section, the press section and finally the drying section. Furthermore, another operation (calendering) may be used to improve the surface smoothness. Forming, pressing and drying are not on the scope of this paper, but the influence of formation and calendering on surface roughness is analyzed. The main objective is to characterize the materials and specially its superficial structure. The proposed model is described in order to analyze this topographical aspect. Some experimental results are presented in order to illustrate the interest of this method to better understand physical properties. This work is therefore dedicated to the description of the proposed model: the studied surface is measured at a microscopic scale using for example, a classical stylus profilometry method. Then the obtained surface is transformed using a conformal mapping that retains the surface orientations. Due to the anisotropy of the fiber distribution in the plane of the sheet, the resulting surface is often not isotropic. Hence, the micro facets that identify the interfaces between pores and solid (fibers in the studied case) at the micro level are transformed into a macroscopic equivalent structure. Furthermore, an ellipsoid may be fit to the experimental data in order to obtain a simple model. The ellipticities are proved to be linked for paper to both fiber orientation (through other optical methods) and roughness. These parameters (ellipticities) are shown to be very significant for different end-use properties. Indeed, they shown to be correlated to printing or optical properties, such as gloss for example. We present in a first part the method to obtain a macroscopic description from physical microscopic measurements. Then measurements carried on different paper samples, using a classical

  16. Variation of soil surface roughness under simulated rainfall

    NASA Astrophysics Data System (ADS)

    Tarquis, A. M.; Saa-Requejo, A.; Valencia, J. L.; Moratiel, R.; Paz-Gonzalez, A.

    2012-04-01

    Soil surface micro-topography or roughness (SSR) defines the physical boundary between overland flow and soil. Due to its unique position, soil roughness potentially affects surface processes such as infiltration, flow routing, erosion and sedimentation. Thus the decay of SSR under different rainfall intensities is of most interest in soil erosion. While some authors have chosen exponent function of cumulative rainfall to describe the decay of SSR, others have used the kinetic energy of rainfall. SSR at the field level is an easy visually perceptible notion, but difficult to describe numerically. In this study we didn't use pin-meter or laser techniques to quantify SSR. Percentage of micro-topographic shadows, under fixed sunlight conditions, has been applied based on former works that proved it is an easy and reliable method to estimate SSR. Two experimental plots, of 1m x 1m, were subjected to successive simulated rainfall events with an intensity of 67 mm/h and a height of 2 m. Both plots were a harrowed plot with an oriented roughness and 6% slope. Images were obtained each 15 minutes of rainfall with an incident angle of light of 45° approximately. The image was acquired by an OLYMPUS X-925, having a size of 2976x3968 pixels and corresponding to an area of 75 cm x 100 cm. For denoising process, the image was cropped to 590x800 pixels and for image binarization Indicator Kriging (IK) method was used. Comparisons of both plots respect to SSR evolution, runoff accumulation and shadows morphology are showed. Acknowledgements Funding provided by Spanish Ministerio de Ciencia e Innovación (MICINN) through project no. AGL2010-21501/AGR is greatly appreciated.

  17. Backscattering from a Gaussian distributed, perfectly conducting, rough surface

    NASA Technical Reports Server (NTRS)

    Brown, G. S.

    1977-01-01

    The problem of scattering by random surfaces possessing many scales of roughness is analyzed. The approach is applicable to bistatic scattering from dielectric surfaces, however, this specific analysis is restricted to backscattering from a perfectly conducting surface in order to more clearly illustrate the method. The surface is assumed to be Gaussian distributed so that the surface height can be split into large and small scale components, relative to the electromagnetic wavelength. A first order perturbation approach is employed wherein the scattering solution for the large scale structure is perturbed by the small scale diffraction effects. The scattering from the large scale structure is treated via geometrical optics techniques. The effect of the large scale surface structure is shown to be equivalent to a convolution in k-space of the height spectrum with the following: the shadowing function, a polarization and surface slope dependent function, and a Gaussian factor resulting from the unperturbed geometrical optics solution. This solution provides a continuous transition between the near normal incidence geometrical optics and wide angle Bragg scattering results.

  18. Persistent and automatic intraoperative 3D digitization of surfaces under dynamic magnifications of an operating microscope

    PubMed Central

    Kumar, Ankur N.; Miga, Michael I.; Pheiffer, Thomas S.; Chambless, Lola B.; Thompson, Reid C.; Dawant, Benoit M.

    2014-01-01

    One of the major challenges impeding advancement in image-guided surgical (IGS) systems is the soft-tissue deformation during surgical procedures. These deformations reduce the utility of the patient’s preoperative images and may produce inaccuracies in the application of preoperative surgical plans. Solutions to compensate for the tissue deformations include the acquisition of intraoperative tomographic images of the whole organ for direct displacement measurement and techniques that combines intraoperative organ surface measurements with computational biomechanical models to predict subsurface displacements. The later solution has the advantage of being less expensive and amenable to surgical workflow. Several modalities such as textured laser scanners, conoscopic holography, and stereo-pair cameras have been proposed for the intraoperative 3D estimation of organ surfaces to drive patient-specific biomechanical models for the intraoperative update of preoperative images. Though each modality has its respective advantages and disadvantages, stereo-pair camera approaches used within a standard operating microscope is the focus of this article. A new method that permits the automatic and near real-time estimation of 3D surfaces (at 1Hz) under varying magnifications of the operating microscope is proposed. This method has been evaluated on a CAD phantom object and on full-length neurosurgery video sequences (~1 hour) acquired intraoperatively by the proposed stereovision system. To the best of our knowledge, this type of validation study on full-length brain tumor surgery videos has not been done before. The method for estimating the unknown magnification factor of the operating microscope achieves accuracy within 0.02 of the theoretical value on a CAD phantom and within 0.06 on 4 clinical videos of the entire brain tumor surgery. When compared to a laser range scanner, the proposed method for reconstructing 3D surfaces intraoperatively achieves root mean square

  19. Persistent and automatic intraoperative 3D digitization of surfaces under dynamic magnifications of an operating microscope.

    PubMed

    Kumar, Ankur N; Miga, Michael I; Pheiffer, Thomas S; Chambless, Lola B; Thompson, Reid C; Dawant, Benoit M

    2015-01-01

    One of the major challenges impeding advancement in image-guided surgical (IGS) systems is the soft-tissue deformation during surgical procedures. These deformations reduce the utility of the patient's preoperative images and may produce inaccuracies in the application of preoperative surgical plans. Solutions to compensate for the tissue deformations include the acquisition of intraoperative tomographic images of the whole organ for direct displacement measurement and techniques that combines intraoperative organ surface measurements with computational biomechanical models to predict subsurface displacements. The later solution has the advantage of being less expensive and amenable to surgical workflow. Several modalities such as textured laser scanners, conoscopic holography, and stereo-pair cameras have been proposed for the intraoperative 3D estimation of organ surfaces to drive patient-specific biomechanical models for the intraoperative update of preoperative images. Though each modality has its respective advantages and disadvantages, stereo-pair camera approaches used within a standard operating microscope is the focus of this article. A new method that permits the automatic and near real-time estimation of 3D surfaces (at 1 Hz) under varying magnifications of the operating microscope is proposed. This method has been evaluated on a CAD phantom object and on full-length neurosurgery video sequences (∼1 h) acquired intraoperatively by the proposed stereovision system. To the best of our knowledge, this type of validation study on full-length brain tumor surgery videos has not been done before. The method for estimating the unknown magnification factor of the operating microscope achieves accuracy within 0.02 of the theoretical value on a CAD phantom and within 0.06 on 4 clinical videos of the entire brain tumor surgery. When compared to a laser range scanner, the proposed method for reconstructing 3D surfaces intraoperatively achieves root mean square

  20. Surface Roughness, Areal Topographic Measurement, and Correlation to LCF Behavior in a Nickel-Based Superalloy

    NASA Astrophysics Data System (ADS)

    Ardi, D. T.; Li, Y. G.; Chan, K. H. K.; Bache, M. R.

    2014-10-01

    Surface roughness often determines fatigue performance of advanced engineering components making definition of this parameter essential subsequent to manufacture. Traditionally, topography measurements employ an average amplitude parameter, R a, obtained from a two-dimensional contact measurement. This parameter, however, is highly localised making it relatively unreliable. This study attempts to correlate areal (3D) topographic, measurements with the low cycle fatigue (LCF) performance defined for a nickel-based superalloy (Waspaloy). Three different surface finishes, namely longitudinal polished, circumferential ground, and longitudinal ground were applied to fatigue specimens. The height and orientation of the topographic features with respect to the loading axis were found to affect LCF performance. Results indicate a close correlation between cycles to failure and the maximum height ( S z) and ten-point height ( S 5z) parameters. A power fit to account for the topographic effect was generated based on the experimental data.

  1. Surface roughness of flowable resin composites eroded by acidic and alcoholic drinks

    PubMed Central

    Poggio, Claudio; Dagna, Alberto; Chiesa, Marco; Colombo, Marco; Scribante, Andrea

    2012-01-01

    Aim: The aim of this study is to evaluate the surface roughness of four flowable resin composites following exposure to acidic and alcoholic drinks. Materials and Methods: SureFil SDR flow, TetricEvoFlow, Esthet-X Flow and Amaris Flow HT samples were immersed in artificial saliva, Coca Cola and Chivas Regal Whisky. Each specimen was examined using a Leica DCM 3D microscope: Arithmetical mean height of the surface profiles was measured (Sa). Results: Kruskal-Wallis test showed significant differences among various groups (P<0,001). Mann Whitney test was applied and control groups showed significantly lower Sa values than other groups (P=0,008). Coca Cola groups showed highest Sa values (P<0,021). No significant differences (P=0,14) in surface texture were found among the specimens of the different materials. No significant differences were found among TetricEvoFlow, Esthet-X Flow and Amaris Flow under control conditions nor after Coca Cola application. Under control condition and after Coca Cola application SureFil SDR flow showed significantly higher Sa values. Moreover, after whisky application Amaris Flow showed significantly lower Sa values then the other three groups that showed no significant differences among them. Conclusions: Acidic and alcoholic drinks eroded the surface roughness of all evaluated flowable resin composites. PMID:22557811

  2. Influence of a prophylaxis paste on surface roughness of different composites, porcelain, enamel and dentin surfaces

    PubMed Central

    Yurdaguven, Haktan; Aykor, Arzu; Ozel, Emre; Sabuncu, Hilmi; Soyman, Mubin

    2012-01-01

    Objective: To investigate the effect of a prophylaxis paste on surface roughness of different composites, enamel, dentin and porcelain surfaces. Methods: Three different composites (FiltekZ250/Group1, Filtek Supreme XT/Group2, Premise/Group3), enamel/Group4, dentin/Group5 and porcelain/Group6 samples were used in this study. All specimens were prepared flat by SiC discs and polished with a diamond polishing paste. The surface roughness measurements were determined with a profilometer after polishing (initial surface roughness). Prophylaxis paste was applied to the samples for 12 seconds, renewing every 6 seconds. After cleaning the samples, roughness values were measured again. Data were analyzed by Kruskal Wallis and Dunn’s multiple comparison test. Wilcoxon test was performed for the comparison of the initial and final surface roughness values (P<.05). The results were evaluated within the P<.05 confidence level. Results: The initial and final surface roughness values (μm) were determined as follows: Group1: 0.039±0.009 and 0.157±0.018, Group2: 0.023±0.005 and 0.145±0.027, Group3: 0.028±0.008 and 0.109±0.012, Group4: 0.024±0.006 and 0.071±0.015, Group5: 0.030±0.007 and 0.143±0.029, Group6: 0.024±0.006 and 0.064±0.014. Significant difference was determined between the initial and final values for all groups. Conclusions: Composite and dentin surfaces were more affected by the application of prophylaxis paste than enamel and porcelain surfaces. The prophylaxis paste increased the surface roughness of all groups, but did not reach the bacterial retention roughness rate of 0.2μm. PMID:22229001

  3. ALE3D Simulations of Gap Closure and Surface Ignition for Cookoff Modeling

    SciTech Connect

    Howard, W M; McClelland, M A; Nichols, A L

    2006-06-22

    We are developing ALE3D models to describe the thermal, chemical and mechanical behavior during the heating, ignition and explosive phases of various cookoff phenomena. The candidate models and numerical strategies are being evaluated using benchmark cookoff experiments. ALE3D is a three-dimensional computer code capable of solving the model equations in a coupled fashion through all the phases of the cookoff in a single calculation. For the cookoff experiments, we are interested in representing behavior on widely varying timescales. We have used an implicit hydrodynamics option during the heating phase and an explicit solution method during the explosive phase. To complicate the modeling problem, high heat fluxes cause rapid temperature increases in boundary layers and lead to the formation of gaps between energetic and structural materials and ignition on surfaces. The initially solid energetic and structural materials react to produce gases, which fill the gaps. These materials can also melt and flow. Since an implicit solution method is used, simple no-strength materials models can no longer be used for liquids and gases. In this paper, we discuss and demonstrate choices of materials models for solid/liquid/gas mixtures to be used in conjunction with the implicit solution method. In addition, results are given for mesh movement strategies applied to the opening, closing, and surface ignition within gaps.

  4. Efficient 3D geometric and Zernike moments computation from unstructured surface meshes.

    PubMed

    Pozo, José María; Villa-Uriol, Maria-Cruz; Frangi, Alejandro F

    2011-03-01

    This paper introduces and evaluates a fast exact algorithm and a series of faster approximate algorithms for the computation of 3D geometric moments from an unstructured surface mesh of triangles. Being based on the object surface reduces the computational complexity of these algorithms with respect to volumetric grid-based algorithms. In contrast, it can only be applied for the computation of geometric moments of homogeneous objects. This advantage and restriction is shared with other proposed algorithms based on the object boundary. The proposed exact algorithm reduces the computational complexity for computing geometric moments up to order N with respect to previously proposed exact algorithms, from N(9) to N(6). The approximate series algorithm appears as a power series on the rate between triangle size and object size, which can be truncated at any desired degree. The higher the number and quality of the triangles, the better the approximation. This approximate algorithm reduces the computational complexity to N(3). In addition, the paper introduces a fast algorithm for the computation of 3D Zernike moments from the computed geometric moments, with a computational complexity N(4), while the previously proposed algorithm is of order N(6). The error introduced by the proposed approximate algorithms is evaluated in different shapes and the cost-benefit ratio in terms of error, and computational time is analyzed for different moment orders. PMID:20714011

  5. Effects of scanning orientation on outlier formation in 3D laser scanning of reflective surfaces

    NASA Astrophysics Data System (ADS)

    Wang, Yutao; Feng, Hsi-Yung

    2016-06-01

    Inspecting objects with reflective surfaces using 3D laser scanning is a demanded but challenging part inspection task due to undesirable specular reflections, which produce extensive outliers in the scanned point cloud. These outliers need to be removed in order to alleviate subsequent data processing issues. Many existing automatic outlier removal methods do not detect outliers according to the outlier formation properties. As a result, these methods only offer limited capabilities in removing extensive and complex outliers from scanning objects with reflective surfaces. This paper reports an empirical study which experimentally investigates the outlier formation characteristics in relation to the scanning orientation of the laser probe. The objective is to characterize the scanning orientation effects on outlier formation in order to facilitate the development of an effective outlier detection and removal method. Such an experimental investigation was hardly done before. It has been found in this work that scanning orientation can directly affect outlier extensity and occurrence in 3D laser scanning. A general guidance on proper scan path planning can then be provided with an aim to reduce the occurrence of outliers. Further, the observed dependency of outlier formation on scanning orientation can be exploited to facilitate effective and automatic outlier detection and removal.

  6. The effect of surface roughness on Triton's volatile distribution

    NASA Technical Reports Server (NTRS)

    Yelle, Roger V.

    1992-01-01

    Calculations of radiative equilibrium temperatures on Triton's rough surface suggest that significant condensation of N2 may be occurring in the northern equatorial regions, despite their relatively dark appearance. The bright frost is not apparent in the Voyager images because it tends to be concentrated in relatively unilluminated facets of the surface. This patchwork of bright frost-covered regions and darker bare ground may be distributed on scales smaller than that of the Voyager resolution; as a result the northern equatorial regions may appear relatively dark. This hypothesis also accounts for the observed wind direction in the Southern Hemisphere because it implies that the equatorial regions are warmer than the south polar regions.

  7. Industrial characterization of nano-scale roughness on polished surfaces

    NASA Astrophysics Data System (ADS)

    Feidenhans'l, Nikolaj A.; Hansen, Poul-Erik; Pilný, Lukáš; Madsen, Morten H.; Bissacco, Giuliano; Petersen, Jan C.; Taboryski, Rafael

    2015-10-01

    We report a correlation between the scattering value "Aq" and the ISO standardized roughness parameter Rq. The Aq value is a measure for surface smoothness, and can easily be determined from an optical scattering measurement. The correlation equation extrapolates the Aq value from a narrow measurement range of +/-16° from specular to a broader range of +/-80°, corresponding to spatial surface wavelengths of 0.8 μm to 25 μm, and converts the Aq value to the Rq value for the surface. Furthermore, we present an investigation of the changes in scattering intensities, when a surface is covered with a thin liquid film. It is shown that the changes in the angular scattering intensities can be compensated for the liquid film, using empirically determined relations. This allows a restoration of the "true" scattering intensities which would be measured from a corresponding clean surface. The compensated scattering intensities provide Aq values within 5.7 % +/- 6.1 % compared to the measurements on clean surfaces.

  8. Contact Interface Verification for DYNA3D Scenario 2: Multi-Surface Contact

    SciTech Connect

    McMichael, L D

    2006-05-10

    A suite of test problems has been developed to examine contact behavior within the nonlinear, three-dimensional, explicit finite element analysis (FEA) code DYNA3D (Lin, 2005). The test problems use multiple interfaces and a combination of enforcement methods to assess the basic functionality of the contact algorithms. The results from the DYNA3D analyses are compared to closed form solutions to verify the contact behavior. This work was performed as part of the Verification and Validation efforts of LLNL W Program within the NNSA's Advanced Simulation and Computing (ASC) Program. DYNA3D models the transient dynamic response of solids and structures including the interactions between disjoint bodies (parts). A wide variety of contact surfaces are available to represent the diverse interactions possible during an analysis, including relative motion (sliding), separation and gap closure (voids), and fixed relative position (tied). The problem geometry may be defined using a combination of element formulations, including one-dimensional beam and truss elements, two-dimensional shell elements, and three-dimensional solid elements. Consequently, it is necessary to consider various element interactions during contact. This report and associated test problems examine the scenario where multiple bodies interact with each other via multiple interfaces. The test problems focus on whether any ordering issues exist in the contact logic by using a combination of interface types, contact enforcement options (i.e., penalty, Lagrange, and kinematic), and element interactions within each problem. The influence of rigid materials on interface behavior is also examined. The companion report (McMichael, 2006) and associated test problems address the basic contact scenario where one contact surface exists between two disjoint bodies. The test problems are analyzed using version 5.2 (compiled on 12/22/2005) of DYNA3D. The analytical results are used to form baseline solutions for

  9. Variations of surface roughness for deposition of Co-sputtered-ZnO(002) by Auger electron spectroscopy and surface magneto-optic Faraday effect

    NASA Astrophysics Data System (ADS)

    Chang, Y.-C.; Su, C.-W.; Chang, S.-C.; Lee, Y.-H.

    2011-02-01

    Auger electron spectroscopy and the surface magneto-optical Faraday effect were used to monitor the deposition of Co ultrathin films on an initially rough ZnO(002) crystal surface. The magnetic properties of the epitaxial films were compared with those associated with that the structure properties in a 3D island growth mode. The magneto-optic signals are very sensitive to the thickness of the Co film structure, even if it is rough. The ZnO(002) substrate surface formed by routine ion sputtering may exhibit short-range ordering in the initial sample preparation. The roughness of a sputtered substrate surface can be determined from the sensitive magneto-optical signals, especially when ultrathin films are deposited in the initial stage of growth.

  10. Uncertainty studies of topographical measurements on steel surface corrosion by 3D scanning electron microscopy.

    PubMed

    Kang, K W; Pereda, M D; Canafoglia, M E; Bilmes, P; Llorente, C; Bonetto, R

    2012-02-01

    Pitting corrosion is a damage mechanism quite serious and dangerous in both carbon steel boiler tubes for power plants which are vital to most industries and stainless steels for orthopedic human implants whose demand, due to the increase of life expectation and rate of traffic accidents, has sharply increased. Reliable methods to characterize this kind of damage are becoming increasingly necessary, when trying to evaluate the advance of damage and to establish the best procedures for component inspection in order to determine remaining lives and failure mitigation. A study about the uncertainties on the topographies of corrosion pits from 3D SEM images, obtained at low magnifications (where errors are greater) and different stage tilt angles were carried out using an in-house software previously developed. Additionally, measurements of pit depths on biomaterial surfaces, subjected to two different surface treatments on stainless steels, were carried out. The different depth distributions observed were in agreement with electrochemical measurements. PMID:22051087

  11. GlaRe, a GIS tool to reconstruct the 3D surface of palaeoglaciers

    NASA Astrophysics Data System (ADS)

    Pellitero, Ramón; Rea, Brice R.; Spagnolo, Matteo; Bakke, Jostein; Ivy-Ochs, Susan; Frew, Craig R.; Hughes, Philip; Ribolini, Adriano; Lukas, Sven; Renssen, Hans

    2016-09-01

    Glacier reconstructions are widely used in palaeoclimatic studies and this paper presents a new semi-automated method for generating glacier reconstructions: GlaRe, is a toolbox coded in Python and operating in ArcGIS. This toolbox provides tools to generate the ice thickness from the bed topography along a palaeoglacier flowline applying the standard flow law for ice, and generates the 3D surface of the palaeoglacier using multiple interpolation methods. The toolbox performance has been evaluated using two extant glaciers, an icefield and a cirque/valley glacier from which the subglacial topography is known, using the basic reconstruction routine in GlaRe. Results in terms of ice surface, ice extent and equilibrium line altitude show excellent agreement that confirms the robustness of this procedure in the reconstruction of palaeoglaciers from glacial landforms such as frontal moraines.

  12. Molecular surface point environments for virtual screening and the elucidation of binding patterns (MOLPRINT 3D).

    PubMed

    Bender, Andreas; Mussa, Hamse Y; Gill, Gurprem S; Glen, Robert C

    2004-12-16

    A novel method (MOLPRINT 3D) for virtual screening and the elucidation of ligand-receptor binding patterns is introduced that is based on environments of molecular surface points. The descriptor uses points relative to the molecular coordinates, thus it is translationally and rotationally invariant. Due to its local nature, conformational variations cause only minor changes in the descriptor. If surface point environments are combined with the Tanimoto coefficient and applied to virtual screening, they achieve retrieval rates comparable to that of two-dimensional (2D) fingerprints. The identification of active structures with minimal 2D similarity ("scaffold hopping") is facilitated. In combination with information-gain-based feature selection and a naive Bayesian classifier, information from multiple molecules can be combined and classification performance can be improved. Selected features are consistent with experimentally determined binding patterns. Examples are given for angiotensin-converting enzyme inhibitors, 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors, and thromboxane A2 antagonists. PMID:15588092

  13. Effects of 3D Toroidally Asymmetric Magnetic Field on Tokamak Magnetic Surfaces

    NASA Astrophysics Data System (ADS)

    Lao, L. L.

    2005-10-01

    The effects of 3D error magnetic field on magnetic surfaces are investigated using the DIII-D internal coils (I-Coils). Slowly rotating n=1 traveling waves at 5 Hz and various amplitudes were applied to systematically perturb the edge surfaces by programming the I-Coil currents. The vertical separatrix location difference between EFIT magnetic reconstructions that assumes toroidal symmetry and Thomson scattering Te measurements responds in phase to the applied perturbed field. The oscillation amplitudes increase with the strength of the applied field but are much smaller than those expected from the applied field alone. The results indicate that plasma response is important. Various plasma response models based on results from the MHD codes MARS and GATO are being developed and compared to the experimental observations. To more accurately evaluate the effects of magnetic measurement errors, a new form of the magnetic uncertainty matrix is also being implemented into EFIT. Details will be presented.

  14. 3D Ag/ZnO hybrids for sensitive surface-enhanced Raman scattering detection

    NASA Astrophysics Data System (ADS)

    Huang, Chenyue; Xu, Chunxiang; Lu, Junfeng; Li, Zhaohui; Tian, Zhengshan

    2016-03-01

    To combine the surface plasma resonance of metal and local field enhancement in metal/semiconductor interface, Ag nanoparticles (NPs) were assembled on a ZnO nanorod array which was grown by hydrothermally on carbon fibers. The construction of dimensional (3D) Surface-Enhanced Raman Scattering (SERS) substrate is used for the sensitive detection of organic pollutants with the advantages such as facile synthesis, short detection time and low cost. The hybrid substrate was manifested a high sensitivity to phenol red at a lower concentration of 1 × 10-9 M and a higher enhancement factor of 3.18 × 109. Moreover, the ZnO nanostructures decorated with Ag NPs were demonstrated self-cleaning function under UV irradiation via photocatalytic degradation of the analytic molecules. The fabrication process of the materials and sensors, optimization of the SERS behaviors for different sized Ag NPs, the mechanism of SERS and recovery were presented with a detailed discussion.

  15. Surface Roughness Effects on Runoff and Soil Erosion Rates Under Simulated Rainfall

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil surface roughness is identified as one of the controlling factors governing runoff and soil loss, yet, most studies pay little attention to soil surface roughness. In this study, we analyzed the influence of random soil surface roughness on runoff and soil erosion rates. Bulk samples of a silt ...

  16. Surface Roughness effects on Runoff and Soil Erosion Rates Under Simulated Rainfall

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil surface roughness is identified as one of the controlling factors governing runoff and soil loss yet, most studies pay little attention to soil surface roughness. In this study, we analyzed the influence of random soil surface roughness on runoff and soil erosion rates. Bulk samples of a silt l...

  17. Non-Newtonian Fluids Spreading with Surface Tension Effect: 3D Numerical Analysis Using FEM and Experimental Study

    NASA Astrophysics Data System (ADS)

    Hu, Bin; Kieweg, Sarah

    2010-11-01

    Gravity-driven thin film flow down an incline is studied for optimal design of polymeric drug delivery vehicles, such as anti-HIV topical microbicides. We develop a 3D FEM model using non-Newtonian mechanics to model the flow of gels in response to gravity, surface tension and shear-thinning. Constant volume setup is applied within the lubrication approximation scope. The lengthwise profiles of the 3D model agree with our previous 2D finite difference model, while the transverse contact line patterns of the 3D model are compared to the experiments. With incorporation of surface tension, capillary ridges are observed at the leading front in both 2D and 3D models. Previously published studies show that capillary ridge can amplify the fingering instabilities in transverse direction. Sensitivity studies (2D & 3D) and experiments are carried out to describe the influence of surface tension and shear-thinning on capillary ridge and fingering instabilities.

  18. Construction of Extended 3D Field of Views of the Internal Bladder Wall Surface: A Proof of Concept

    NASA Astrophysics Data System (ADS)

    Ben-Hamadou, Achraf; Daul, Christian; Soussen, Charles

    2016-09-01

    3D extended field of views (FOVs) of the internal bladder wall facilitate lesion diagnosis, patient follow-up and treatment traceability. In this paper, we propose a 3D image mosaicing algorithm guided by 2D cystoscopic video-image registration for obtaining textured FOV mosaics. In this feasibility study, the registration makes use of data from a 3D cystoscope prototype providing, in addition to each small FOV image, some 3D points located on the surface. This proof of concept shows that textured surfaces can be constructed with minimally modified cystoscopes. The potential of the method is demonstrated on numerical and real phantoms reproducing various surface shapes. Pig and human bladder textures are superimposed on phantoms with known shape and dimensions. These data allow for quantitative assessment of the 3D mosaicing algorithm based on the registration of images simulating bladder textures.

  19. 3-D micro surface profilometry employing novel Mirau-based lateral scanning interferometry

    NASA Astrophysics Data System (ADS)

    Chen, Liang-Chia; Le, Manh-Trung; Lin, Yi-Shiuan

    2014-09-01

    An innovative 3-D surface imaging methodology for reconstructing micro surface profiles with a long depth measuring range and a nano-scale resolution was developed using the newly developed Mirau-based lateral scanning interferometry (LSI). The current measuring field of view (FOV) of conventional white light interferometers is limited by microscopic views of the existing interferometric objectives, such as those in Michelson, Mirau or Linnik designs. Moreover, the vertical scanning operation required for acquiring volumetric interferometric data is extremely time-consuming and makes white light vertical scanning interferometry (VSI) infeasible for automatic optical inspection (AOI) of micro 3-D structures. To resolve this, a newly developed white light LSI method based on Mirau’s optical configuration was developed by controlling the tilting angle of the reference mirror in the Mirau interferometric objective. With the proposed optical configuration, the surface is inspected at a tilting angle with respect to the maximum coherence plane of the interferometric system along its lateral scanning direction when the objective lies perpendicular to the tested surface. In addition, a system calibration method was developed to establish an accurate mathematical mapping model between the object depth and the lateral axis. To evaluate the feasibility of the methodology, a calibrated step height was measured for evaluating the accuracy and repeatability. Some industrial samples, such as photon spacers and other microstructures fabricated by nano-imprinting processes, were measured to verify the actual performance on real components. It was found that the measurement repeatability was controlled less than 60 nm within one standard deviation for a maximum measurable depth of 27.21 µm.

  20. Region-Based 3d Surface Reconstruction Using Images Acquired by Low-Cost Unmanned Aerial Systems

    NASA Astrophysics Data System (ADS)

    Lari, Z.; Al-Rawabdeh, A.; He, F.; Habib, A.; El-Sheimy, N.

    2015-08-01

    Accurate 3D surface reconstruction of our environment has become essential for an unlimited number of emerging applications. In the past few years, Unmanned Aerial Systems (UAS) are evolving as low-cost and flexible platforms for geospatial data collection that could meet the needs of aforementioned application and overcome limitations of traditional airborne and terrestrial mobile mapping systems. Due to their payload restrictions, these systems usually include consumer-grade imaging and positioning sensor which will negatively impact the quality of the collected geospatial data and reconstructed surfaces. Therefore, new surface reconstruction surfaces are needed to mitigate the impact of using low-cost sensors on the final products. To date, different approaches have been proposed to for 3D surface construction using overlapping images collected by imaging sensor mounted on moving platforms. In these approaches, 3D surfaces are mainly reconstructed based on dense matching techniques. However, generated 3D point clouds might not accurately represent the scanned surfaces due to point density variations and edge preservation problems. In order to resolve these problems, a new region-based 3D surface renostruction trchnique is introduced in this paper. This approach aims to generate a 3D photo-realistic model of individually scanned surfaces within the captured images. This approach is initiated by a Semi-Global dense Matching procedure is carried out to generate a 3D point cloud from the scanned area within the collected images. The generated point cloud is then segmented to extract individual planar surfaces. Finally, a novel region-based texturing technique is implemented for photorealistic reconstruction of the extracted planar surfaces. Experimental results using images collected by a camera mounted on a low-cost UAS demonstrate the feasibility of the proposed approach for photorealistic 3D surface reconstruction.

  1. Surface 3D nanostructuring by tightly focused laser pulse: simulations by Lagrangian code and molecular dynamics

    NASA Astrophysics Data System (ADS)

    Inogamov, Nail A.; Zhakhovsky, Vasily V.

    2016-02-01

    There are many important applications in which the ultrashort diffraction-limited and therefore tightly focused laser pulses irradiates metal films mounted on dielectric substrate. Here we present the detailed picture of laser peeling and 3D structure formation of the thin (relative to a depth of a heat affected zone in the bulk targets) gold films on glass substrate. The underlying physics of such diffraction-limited laser peeling was not well understood previously. Our approach is based on a physical model which takes into consideration the new calculations of the two-temperature (2T) equation of state (2T EoS) and the two-temperature transport coefficients together with the coupling parameter between electron and ion subsystems. The usage of the 2T EoS and the kinetic coefficients is required because absorption of an ultrashort pulse with duration of 10-1000 fs excites electron subsystem of metal and transfers substance into the 2T state with hot electrons (typical electron temperatures 1-3 eV) and much colder ions. It is shown that formation of submicrometer-sized 3D structures is a result of the electron-ion energy transfer, melting, and delamination of film from substrate under combined action of electron and ion pressures, capillary deceleration of the delaminated liquid metal or semiconductor, and ultrafast freezing of molten material. We found that the freezing is going in non-equilibrium regime with strongly overcooled liquid phase. In this case the Stefan approximation is non-applicable because the solidification front speed is limited by the diffusion rate of atoms in the molten material. To solve the problem we have developed the 2T Lagrangian code including all this reach physics in. We also used the high-performance combined Monte- Carlo and molecular dynamics code for simulation of surface 3D nanostructuring at later times after completion of electron-ion relaxation.

  2. Free-Surface Roughness Correlations with the Near-Surface Turbulence

    NASA Astrophysics Data System (ADS)

    Dabiri, Dana; Gharib, Morteza

    1999-11-01

    Free-Surface Roughness Correlations with the Near-Surface Turbulence Dana Dabiri & Morteza Gharib CALTECH Understanding the correlation of the free-surface roughness with the near-surface turbulence can provide correct and proper models for LES and RANS codes. Measurements of both the near surface turbulence, and the free surface deformation are obtained simultaneously. The near surface turbulence is measured using DPIV, and the free surface roughness is measured using a two-dimensional gradient detector. These measurements were done looking at a shear layer interacting with a free surface. The Reynold's number and Froude number are 7000, and 0.07, respectively. Statistical calculations provide interesting u'v', h'v', h'u', h'u'v', and h'w' results. Spanwise Reynold's stress (u'v') plots show a gaussian behavior, while its centerline value is roughly constant with y. h'u' is symmetric with respect to the shear layer's centerline, showing a negative correlation on the high speed side and a positive correlation on the low speed side. Correlation of h' with the vorticity fluctuation, w', shows a skewed gaussian spanwise behavior. Lastly, the roughness spectrum shows a -11/3 spectra, as shown by George et al. (JFM, 1984). *Sponsored by ONR (N00014-98-1-0017)

  3. On the Mean Flow Behaviour in the Presence of Regional-Scale Surface Roughness Heterogeneity

    NASA Astrophysics Data System (ADS)

    Yang, Xiang I. A.

    2016-05-01

    A suite of large-eddy simulations of the neutral atmospheric boundary layer is conducted to study the mean flow response to the presence of surface roughness heterogeneity at regional scales (surface roughness heterogeneity on the scale of several boundary-layer heights). The roughness heterogeneity is imposed using alternating rough wall patches with numerically resolved rectangular roughness elements of different packing densities. The flow near the surface is found to adjust rapidly, reaching equilibrium conditions at distances on the order of a single inter-roughness element spacing. Despite the regional heterogeneity in surface roughness, it is often desirable to parametrize the entire rough wall using one single effective roughness height. To develop such a parametrization the model of Bou-Zeid et al. [Water Resources Research 40(2):1, 2004] is extended to incorporate the displacement height, d. Predictions from this parametrization are compared with the simulations, with reasonably good agreement.

  4. Quantifying trends in surface roughness and the effect on surface wind speed observations

    NASA Astrophysics Data System (ADS)

    Wever, N.

    2012-06-01

    Many studies analyzing surface wind speed observations find a decrease in wind speed over the last 30 to 50 years. A cause sometimes proposed is increasing surface roughness, although to date the evidence that this is the primary factor is still inconclusive. In this study, changes in surface roughness are investigated for 20 stations in the Netherlands and 137 stations in 7 other European countries. From the Dutch data set, local aerodynamic roughness lengths were calculated from hourly gust factors. Trends in wind speed for individual stations and wind direction sectors correlate negatively with trends in surface roughness. For 1962-2009, typically a doubling of the local roughness length was found, with the strongest increase after 1981. An accompanying average decrease in wind speed by 3.1% (0.13 m/s) per decade was found for 1981-2009. A conceptual boundary layer model was used to show that 70% of the wind speed trend can be attributed to surface roughness changes; the remaining 30% of the trend remains unresolved. Changes in land use, including urbanization, forestation, and a decrease in pasture land area, are probable causes for the increasing surface roughness. For the European station data from the European Climate Assessment and Dataset (ECA&D) and the Swiss Federal Office of Meteorology and Climatology (MeteoSwiss), the analysis was restricted to daily gust factors. Observed trends in wind speed at stations correlate negatively with trends in gust factors. Averaged over all stations, the wind speed decreased 1.2% (0.05 m/s) per decade over 1982-2009, consistent with increasing surface roughness.

  5. An enhanced method for registration of dental surfaces partially scanned by a 3D dental laser scanning.

    PubMed

    Park, Seongjin; Kang, Ho Chul; Lee, Jeongjin; Shin, Juneseuk; Shin, Yeong Gil

    2015-01-01

    In this paper, we propose the fast and accurate registration method of partially scanned dental surfaces in a 3D dental laser scanning. To overcome the multiple point correspondence problems of conventional surface registration methods, we propose the novel depth map-based registration method to register 3D surface models. First, we convert a partially scanned 3D dental surface into a 2D image by generating the 2D depth map image of the surface model by applying a 3D rigid transformation into this model. Then, the image-based registration method using 2D depth map images accurately estimates the initial transformation between two consequently acquired surface models. To further increase the computational efficiency, we decompose the 3D rigid transformation into out-of-plane (i.e. x-, y-rotation, and z-translation) and in-plane (i.e. x-, y-translation, and z-rotation) transformations. For the in-plane transformation, we accelerate the transformation process by transforming the 2D depth map image instead of transforming the 3D surface model. For the more accurate registration of 3D surface models, we enhance iterative closest point (ICP) method for the subsequent fine registration. Our initial depth map-based registration well aligns each surface model. Therefore, our subsequent ICP method can accurately register two surface models since it is highly probable that the closest point pairs are the exact corresponding point pairs. The experimental results demonstrated that our method accurately registered partially scanned dental surfaces. Regarding the computational performance, our method delivered about 1.5 times faster registration than the conventional method. Our method can be successfully applied to the accurate reconstruction of 3D dental objects for orthodontic and prosthodontic treatment. PMID:25453381

  6. COMPUTER SIMULATIONS OF SPRAY RETENTION BY A 3D BARLEY PLANT: EFFECT OF FORMULATION SURFACE TENSION.

    PubMed

    Massinon, M; De Cock, N; Salah, S Ouled Taleb; Lebeau, F

    2015-01-01

    A spray retention model was used in this study to explore theoretically the effect of a range of mixture surface tension on the spray retention and the variability of deposits. The spray retention model was based on an algorithm that tested whether droplets from a virtual nozzle intercepted a 3D plant model. If so, the algorithm determined the contribution of the droplet to the overall retention depending on the droplet impact behaviour on the leaf; adhesion, rebound or splashing. The impact outcome probabilities, function of droplet impact energy, were measured using high-speed imaging on an excised indoor grown barley leaf (BBCH12) both for pure water (surface tension of 0.072 N/m) and a non-ionic super spreader (static surface tension of 0.021 N/m) depending on the surface orientation. The modification of spray mixture properties in the simulations was performed by gradually changing the spray the droplet impact probabilities between pure water and a solution with non-ionic surfactant exhibiting super spreading properties. The plant architecture was measured using a structured light scanner. The final retention was expressed as the volume of liquid retained by the whole plant relative to the projected leaf surface area in the main spray direction. One hundred simulations were performed at different volumes per hectare and flat-fan nozzles for each formulation surface tension. The coefficient of variation was used as indicator of variability of deposits. The model was able to discriminate between mixture surface tension. The spray retention increased as the mixture surface tension decreased. The variability of deposits also decreased as the surface tension decreased. The proposed modelling approach provides a suited tool for sensitivity analysis: nozzle kind, pressure, volume per hectare applied, spray mixture physicochemical properties, plant species, growth stage could be screened to determine the best spraying characteristics maximizing the retention. The

  7. Radar, visual and thermal characteristics of Mars: Rough planar surfaces

    USGS Publications Warehouse

    Schaber, G.G.

    1980-01-01

    High-resolution Viking Orbiter images (10 to 15 m/pixel) contain significant information on Martian surface roughness at 25- to 100-m lateral scales, whereas Earth-based radar observations of Mars are sensitive to roughness at lateral scales of 1 to 30 m, or more. High-rms slopes predicted for the Tharsis-Memnonia-Amazonis volcanic plains from extremely weak radar returns (low peak radar cross section) are qualitatively confirmed by the Viking image data. Large-scale, curvilinear (but parallel) ridges on lava flows in the Memnonia Fossae region are interpreted as innate flow morphology caused by compressional foldover of moving lava sheets of possible rhyolite-dacite composition. The presence or absence of a recent mantle of fine-grained eolian material on the volcanic surfaces studied was determined by the visibility of fresh impact craters with diameters less than 50 m. Lava flows south and west of Arsia Mons, and within the large region of low thermal inertia centered on Tharsis Montes (H. H. Kieffer et al., 1977, J. Geophys. Res.82, 4249-4291), were found to possess such a recent mantle. At predawn residual temperatures ??? -10K (south boundary of this low-temperature region), lava flows are shown to have relatively old eolian mantles. Lava flows with surfaces modified by eolian erosion and deposition occur west-northwest of Apollinaris Patera at the border of the cratered equatorial uplands and southern Elysium Planitia. Nearby yardangs, for which radar observations indicate very high-rms slopes, are similar to terrestrial features of similar origin. ?? 1980.

  8. 3D Imaging of Water-Drop Condensation on Hydrophobic and Hydrophilic Lubricant-Impregnated Surfaces

    PubMed Central

    Kajiya, Tadashi; Schellenberger, Frank; Papadopoulos, Periklis; Vollmer, Doris; Butt, Hans-Jürgen

    2016-01-01

    Condensation of water from the atmosphere on a solid surface is an ubiquitous phenomenon in nature and has diverse technological applications, e.g. in heat and mass transfer. We investigated the condensation kinetics of water drops on a lubricant-impregnated surface, i.e., a micropillar array impregnated with a non-volatile ionic liquid. Growing and coalescing drops were imaged in 3D using a laser scanning confocal microscope equipped with a temperature and humidity control. Different stages of condensation can be discriminated. On a lubricant-impregnated hydrophobic micropillar array these are: (1) Nucleation on the lubricant surface. (2) Regular alignment of water drops between micropillars and formation of a three-phase contact line on a bottom of the substrate. (3) Deformation and bridging by coalescence which eventually leads to a detachment of the drops from the bottom substrate. The drop-substrate contact does not result in breakdown of the slippery behaviour. Contrary, on a lubricant-impregnated hydrophilic micropillar array, the condensed water drops replace the lubricant. Consequently, the surface loses its slippery property. Our results demonstrate that a Wenzel-like to Cassie transition, required to maintain the facile removal of condensed water drops, can be induced by well-chosen surface hydrophobicity. PMID:27040483

  9. 3D Imaging of Water-Drop Condensation on Hydrophobic and Hydrophilic Lubricant-Impregnated Surfaces

    NASA Astrophysics Data System (ADS)

    Kajiya, Tadashi; Schellenberger, Frank; Papadopoulos, Periklis; Vollmer, Doris; Butt, Hans-Jürgen

    2016-04-01

    Condensation of water from the atmosphere on a solid surface is an ubiquitous phenomenon in nature and has diverse technological applications, e.g. in heat and mass transfer. We investigated the condensation kinetics of water drops on a lubricant-impregnated surface, i.e., a micropillar array impregnated with a non-volatile ionic liquid. Growing and coalescing drops were imaged in 3D using a laser scanning confocal microscope equipped with a temperature and humidity control. Different stages of condensation can be discriminated. On a lubricant-impregnated hydrophobic micropillar array these are: (1) Nucleation on the lubricant surface. (2) Regular alignment of water drops between micropillars and formation of a three-phase contact line on a bottom of the substrate. (3) Deformation and bridging by coalescence which eventually leads to a detachment of the drops from the bottom substrate. The drop-substrate contact does not result in breakdown of the slippery behaviour. Contrary, on a lubricant-impregnated hydrophilic micropillar array, the condensed water drops replace the lubricant. Consequently, the surface loses its slippery property. Our results demonstrate that a Wenzel-like to Cassie transition, required to maintain the facile removal of condensed water drops, can be induced by well-chosen surface hydrophobicity.

  10. 3D Imaging of Water-Drop Condensation on Hydrophobic and Hydrophilic Lubricant-Impregnated Surfaces.

    PubMed

    Kajiya, Tadashi; Schellenberger, Frank; Papadopoulos, Periklis; Vollmer, Doris; Butt, Hans-Jürgen

    2016-01-01

    Condensation of water from the atmosphere on a solid surface is an ubiquitous phenomenon in nature and has diverse technological applications, e.g. in heat and mass transfer. We investigated the condensation kinetics of water drops on a lubricant-impregnated surface, i.e., a micropillar array impregnated with a non-volatile ionic liquid. Growing and coalescing drops were imaged in 3D using a laser scanning confocal microscope equipped with a temperature and humidity control. Different stages of condensation can be discriminated. On a lubricant-impregnated hydrophobic micropillar array these are: (1) Nucleation on the lubricant surface. (2) Regular alignment of water drops between micropillars and formation of a three-phase contact line on a bottom of the substrate. (3) Deformation and bridging by coalescence which eventually leads to a detachment of the drops from the bottom substrate. The drop-substrate contact does not result in breakdown of the slippery behaviour. Contrary, on a lubricant-impregnated hydrophilic micropillar array, the condensed water drops replace the lubricant. Consequently, the surface loses its slippery property. Our results demonstrate that a Wenzel-like to Cassie transition, required to maintain the facile removal of condensed water drops, can be induced by well-chosen surface hydrophobicity. PMID:27040483

  11. A combined 3D and hyperspectral method for surface imaging of wounds

    NASA Astrophysics Data System (ADS)

    Paluchowski, Lukasz A.; Denstedt, Martin; Røren, Thomas; Pukstad, Brita; Randeberg, Lise Lyngsnes

    2013-03-01

    Information about the size and depth of a wound and how it is developing is an important prognostic tool in wound diagnostics. In this study a two-camera vision system has been developed to collect optical properties, shape and volume of chronic skin ulcers as tool for diagnostic assistance. This system combines the functionality of 2D imaging spectroscopy and 3D stereo-photogrammetry. A high resolution hyperspectral camera and a monochromatic video frame camera were mounted on the same scanning system. Stereo images were acquired to obtain information about the wound surface geometry. A Digital Surface Model (DSM) of the wound surface was reconstructed by applying stereophotogrammetric methods. The hyperspectral image was co-registered to the monochromatic frame image and the wound border was extracted by applying spectroscopic analysis (e.g. tissue oxygenation, pigmentation, classification). The resulting DSM of the undamaged surroundings of the wound was used to reconstruct the top surface above the wound and thus the wound volume. The analyses can, if desired, be limited to a certain depth of interest like the wound bed or wound border. Simultaneous analysis of the hyperspectral data and the surface model gives a promising, new, non-invasive tool for characterization of chronic wounds. Future work will concentrate on implementation of real time analysis and improvement of the accuracy of the system.

  12. Visual and digital comparative tooth colour assessment methods and atomic force microscopy surface roughness.

    PubMed

    Grundlingh, A A; Grossman, E S; Shrivastava, S; Witcomb, M J

    2013-10-01

    This study compared digital and visual colour tooth colour assessment methods in a sample of 99 teeth consisting of incisors, canines and pre-molars. The teeth were equally divided between Control, Ozicure Oxygen Activator bleach and Opalescence Quick bleach and subjected to three treatments. Colour readings were recorded at nine intervals by two assessment methods, VITA Easyshade and VITAPAN 3D MASTER TOOTH GUIDE, giving a total of 1782 colour readings. Descriptive and statistical analysis was undertaken using a GLM test for Analysis of Variance for a Fractional Design set at a significance of P < 0.05. Atomic force micros copy was used to examine treated ename surfaces and establish surface roughness. Visual tooth colour assessment showed significance for the independent variables of treatment, number of treatments, tooth type and the combination tooth type and treatment. Digital colour assessment indicated treatment and tooth type to be of significance in tooth colour change. Poor agreement was found between visual and digital colour assessment methods for Control and Ozicure Oxygen Activator treatments. Surface roughness values increased two-fold for Opalescence Quick specimens over the two other treatments, implying that increased light scattering improved digital colour reading. Both digital and visual colour matching methods should be used in tooth bleaching studies to complement each other and to compensate for deficiencies. PMID:24660413

  13. 3D Surface Reconstruction of Rills in a Spanish Olive Grove

    NASA Astrophysics Data System (ADS)

    Brings, Christine; Gronz, Oliver; Seeger, Manuel; Wirtz, Stefan; Taguas, Encarnación; Ries, Johannes B.

    2016-04-01

    The low-cost, user-friendly photogrammetric Structure from Motion (SfM) technique is used for 3D surface reconstruction and difference calculation of an 18 meter long rill in South Spain (Andalusia, Puente Genil). The images were taken with a Canon HD video camera before and after a rill experiment in an olive grove. Recording with a video camera has compared to a photo camera a huge time advantage and the method also guarantees more than adequately overlapping sharp images. For each model, approximately 20 minutes of video were taken. As SfM needs single images, the sharpest image was automatically selected from 8 frame intervals. The sharpness was estimated using a derivative-based metric. Then, VisualSfM detects feature points in each image, searches matching feature points in all image pairs and recovers the camera and feature positions. Finally, by triangulation of camera positions and feature points the software reconstructs a point cloud of the rill surface. From the point cloud, 3D surface models (meshes) are created and via difference calculations of the pre and post model a visualization of the changes (erosion and accumulation areas) and quantification of erosion volumes are possible. The calculated volumes are presented in spatial units of the models and so real values must be converted via references. The results show that rills in olive groves have a high dynamic due to the lack of vegetation cover under the trees, so that the rill can incise until the bedrock. Another reason for the high activity is the intensive employment of machinery.

  14. Automated surface micro-machining mask creation from a 3D model.

    SciTech Connect

    Schiek, Richard Louis; Schmidt, Rodney Cannon

    2004-06-01

    We have developed and implemented a method, which given a three-dimensional object can infer from topology the two-dimensional masks needed to produce that object with surface micromachining. The masks produced by this design tool can be generic, process independent masks, or if given process constraints, specific for a target process. This design tool calculates the two-dimensional mask set required to produce a given three-dimensional model by investigating the vertical topology to the model. The 3D model is first separated into bodies that are non-intersecting, made from different materials or only linked through a ground plane. Next, for each body unique vertical cross sections are located and arranged into a tree based on their topological relationship. A branch-wise search of the tree uncovers locations where deposition boundaries must lie and identifies candidate masks creating a generic mask set for the 3D model. Finally, in the last step specific process requirements are considered that may constrain the generic mask set. Constraints can include the thickness or number of deposition layers, specific ordering of masks as required by a process and type of material used in a given layer. Candidate masks are reconciled with the process constraints through a constrained optimization.

  15. 3D face recognition using simulated annealing and the surface interpenetration measure.

    PubMed

    Queirolo, Chauã C; Silva, Luciano; Bellon, Olga R P; Segundo, Maurício Pamplona

    2010-02-01

    This paper presents a novel automatic framework to perform 3D face recognition. The proposed method uses a Simulated Annealing-based approach (SA) for range image registration with the Surface Interpenetration Measure (SIM), as similarity measure, in order to match two face images. The authentication score is obtained by combining the SIM values corresponding to the matching of four different face regions: circular and elliptical areas around the nose, forehead, and the entire face region. Then, a modified SA approach is proposed taking advantage of invariant face regions to better handle facial expressions. Comprehensive experiments were performed on the FRGC v2 database, the largest available database of 3D face images composed of 4,007 images with different facial expressions. The experiments simulated both verification and identification systems and the results compared to those reported by state-of-the-art works. By using all of the images in the database, a verification rate of 96.5 percent was achieved at a False Acceptance Rate (FAR) of 0.1 percent. In the identification scenario, a rank-one accuracy of 98.4 percent was achieved. To the best of our knowledge, this is the highest rank-one score ever achieved for the FRGC v2 database when compared to results published in the literature. PMID:20075453

  16. 3D Simulation of Missing Pellet Surface Defects in Light Water Reactor Fuel Rods

    SciTech Connect

    B.W. Spencer; J.D. Hales; S.R. Novascone; R.L. Williamson

    2012-09-01

    The cladding on light water reactor (LWR) fuel rods provides a stable enclosure for fuel pellets and serves as a first barrier against fission product release. Consequently, it is important to design fuel to prevent cladding failure due to mechanical interactions with fuel pellets. Cladding stresses can be effectively limited by controlling power increase rates. However, it has been shown that local geometric irregularities caused by manufacturing defects known as missing pellet surfaces (MPS) in fuel pellets can lead to elevated cladding stresses that are sufficiently high to cause cladding failure. Accurate modeling of these defects can help prevent these types of failures. Nuclear fuel performance codes commonly use a 1.5D (axisymmetric, axially-stacked, one-dimensional radial) or 2D axisymmetric representation of the fuel rod. To study the effects of MPS defects, results from 1.5D or 2D fuel performance analyses are typically mapped to thermo-mechanical models that consist of a 2D plane-strain slice or a full 3D representation