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991.
992.
Julia Armesto Izabela Lubowiecka Celestino Ordóñez Fernando I. Rial 《Automation in Construction》2009,18(5):559-569
The aim of this paper is to present a methodology for the evaluation of historic timber structures, based on numerical modeling coupled with on site measurements. A method to measure the geometry of structural elements of a timber roof using a photogrammetric modeling procedure is described. In particular, we show the utility of photogrammetric based models when applied to structural analysis by directly introducing 3D geometry files in the preprocessing module of computational software based on the Finite Element Method. The 2D and 3D FEM models of the roof are considered to compare the simple and more complex modeling, and static and dynamic analyses are performed. Both models are prepared using the photogrammetric data. 相似文献
993.
The purpose of these field and lab studies undertaken during rehabilitation work being done on an ancient railway line was to characterize a layer of ballast fouled with soil found in the track substructure. The field studies included the characterization of the thickness, grain size distribution and void ratio of the fouled ballast layer, as well as a large number of plate load tests, both on the fouled ballast layer and on the subgrade. The resilient behaviour of the fouled ballast was evaluated in the lab by cyclic triaxial tests on large size reconstituted specimens with distinct fouling indexes (different grain size distribution) and distinct humidity states (dry or wet). The results obtained were used as support for the decision to maintain the fouled ballast layer under the new sub-ballast in a number of stretches of the renewed line. 相似文献
994.
López Steven R.; Lara Ma. del Carmen; Kopelowicz Alex; Solano Susana; Foncerrada Hector; Aguilera Adrian 《Canadian Metallurgical Quarterly》2009,77(4):763
The authors developed and tested a 35-min psychoeducational program with the goal of increasing Spanish-speaking persons’ literacy of psychosis. The program uses popular cultural icons derived from music, art, and videos, as well as a mnemonic device—La CLAve (The Clue)—to increase (a) knowledge of psychosis, (b) efficacy beliefs that one can identify psychosis in others, (c) attributions to mental illness, and (d) professional help-seeking. Assessments were conducted before and after administering the program to both community residents (n = 57) and family caregivers of persons with schizophrenia (n = 38). For community residents, the authors observed increases across the 4 domains of symptom knowledge, efficacy beliefs, illness attributions, and recommended help-seeking. For caregivers, increases were observed in symptom knowledge and efficacy beliefs. La CLAve is a conceptually informed psychoeducational tool with a developing empirical base aimed at helping Spanish-speaking Latinos with serious mental illness obtain care in a timely manner. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
995.
Francisco López-Carrasquero Giuseppe Giammanco Angélica Díaz Johanna Dávila Carlos Torres Estrella Laredo 《Polymer Bulletin》2009,63(1):69-78
A series of comb like poly(p-n-alkylstyrene)s with linear alkyl groups, containing even numbers of carbon atoms from 12 up to 22 were synthesized by radical
polymerization and characterized by FTIR, 1H NMR, TGA, TVA DSC, and WAXS. All polymers were obtained in good yields and were soluble in organic solvents as chloroform,
dichloromethane or tetrahydrofuran and insoluble in methanol; they are stable up to temperatures near 300 °C. On the other
hand, the alkylic side chains of all series are able to crystallize in a paraffinic phase in which the melting temperature
and enthalpy increase with the methylene number of the n-alkyl chain. 相似文献
996.
The effect of copper addition in the microstructure of sol–gel titanium oxide (TiO2) supported on anodic aluminum oxide (AAO) membranes is reported. Two deposition methods based on immersion and flow techniques
were used for the coating of the porous AAO membrane. Copper-free membranes were studied as a function of different ratios
of H+/Ti, H2O/Ti, selecting the most appropriate for the sensitization with copper. For copper-doped TiO2 arrays, the presence of copper causes the reduction of grain size and enhances titania deposition inside the AAO pores, although
no clear tendency with copper content was found. The formation of copper-doped titania nanotubes was validated after dissolving
the AAO membranes, finding a deposition-dependent stability in the Cu-doped materials. Titania and Cu-doped titania nanotubes
analyzed as colloidal solutions show band gaps substantially shifted to the red in comparison to the direct band gap of near-spherical
colloidal materials. These arrays are important for photocatalysis and for the development of third generation photovoltaic
devices. 相似文献
997.
J. F. Román-Zamorano M. Flores-Acosta H. Arizpe-Chávez F. F. Castillón-Barraza M. H. Farías R. Ramírez-Bon 《Journal of Materials Science》2009,44(18):4781-4788
We have synthesized lead and lead sulfide nanoparticles embedded in a natural zeolite (clinoptilolite) matrix by a simple
hydrothermal process. The process steps involve the partial removing of the natural cations in clinoptilolite, the ion-exchange
process to enclose Pb ions and nanoparticles and finally a sulfuration process at different temperatures to obtain lead sulfide
phases in the zeolite matrix. The samples were studied by X-ray diffraction, diffuse reflectance spectroscopy, energy dispersive
X-ray spectroscopy, X-ray photon spectroscopy and transmission electron microscopy. The experimental results show the inclusion
of three Pb species with different valence states after the Pb ion-exchange step, namely Pb2+, Pb4+, and Pb0. At the end of the process, two simultaneous lead sulfide crystalline phases, PbS (Galena) and PbS2 (tetragonal) were synthesized in the clinoptilolite matrix. The optical absorption spectra of the samples show the exciton
absorption peaks typical of colloidal PbS nanoparticles. The average size of the PbS nanoparticles was about 10 nm and their
crystalline structure was determined from diffraction electron patterns. The high-pressure phase PbS2 was also identified and its formation was attributed to the influence of the special conditions of clinoptilolite matrix
as crystallization media to induce some selective nucleation process of this crystalline phase. 相似文献
998.
F. Parres J.E. Crespo-Amorós A. Nadal-Gisbert 《Construction and Building Materials》2009,23(10):3182-3188
The importance of recovering waste materials generated by industrialised societies is mainly due to the environmental impact that they have, and one of the principal problem is the presence of end of life tires. In recent years, an enormous amount of tires has been recycled. The metals they contained have been recovered and the tire particles have been used in several applications. Fibers acting as reinforcement are another material that they appear in the recovery process. Before addressing the possible re-use of these fibers, they have to be characterized and identified. Several techniques of thermal analysis allow these fibers to be identified through melt point analysis, whose results show the presence of polyamide 6 and 6.6.Polyamide fibers have been frequently used as a ceramic and polymer reinforcement, the main advantage of using fiber is to prevent a catastrophic failure of the ceramic material in two pieces. The compression and bending test show differences between samples prepared with different percentages of fiber. 相似文献
999.
Victor Falguera Jorge Fernando Vélez‐Ruiz Verónica Alins Albert Ibarz 《International Journal of Food Science & Technology》2010,45(10):2194-2200
Several rheological properties of concentrated mandarin juice were investigated, quantifying thixotropic behaviour and fitting experimental data to the Hahn, Weltman, and Figoni–Shoemaker equations. The latter one proved best for modelling the time dependency response. Pseudoplastic behaviour fitted well with the Herschel–Bulkley model in the interval between ?12 and 6 °C, in which yield stress and the flow behaviour index scarcely changed with temperature. The consistency coefficient and apparent viscosity both decreased as temperature increased. Fitting these consistency data to the Arrhenius‐type equation, a value of 33 kJ mol?1 for activation energy was obtained. Concentrated mandarin juice displayed viscoelastic properties in the temperature range between ?12 and 6 °C, with the elastic character (determined by the juice’s pectin content) predominating over the viscous nature at low frequency values, but with this behaviour being inverted for high values. Furthermore, as the temperature became higher, the elastic character became more important than the viscous nature. 相似文献
1000.
Celestino Ordóñez Joaquín Martínez Pedro Arias Julia Armesto 《Automation in Construction》2010,19(6):742-749
The dimensions of façades and window openings are usually determined by direct measurements using tapes and plummets. These direct methods are time consuming and risky for operators, so indirect approaches are needed. In this paper, we analyse a planar-surface measuring system based on close-range photogrammetry to determine its accuracy and precision. This system is composed of a digital camera and a laser distance meter mounted on a support that allows the laser distance meter to be moved independently of the camera. The proposed system can determine the dimensions of objects. Also, this system provides an estimation of the precision of the calculations for the distances between points. By knowing the uncertainty of their measurements, users can accept or reject the measurement depending on the application tolerance. 相似文献