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961.
We built a portable low-cost superconducting quantum interference device (SQUID) magnetometer to be used as the sensing element
of an electric current injection NDE system. Using this system, we measured the magnetic fields associated with aluminum plate
with single flaws in the millimeter range (2 to 8 mm), at lift-off distances up to ten times the size of the flaw, with injection
currents in the order of a few amps. Because the system is at a relatively large distance from the test plate, the signal
generated by the flaw is masked by the sinal generated by the edges of the plate. This is independent of the amount of current
injected. Due to this, visual inspection is difficult when the distance from the sensor to the flaw exceeds five times its
size. To intensify the magnetic field disturbance due to the flaws, we used digital image-enhancement techniques. Applying
the enhancement algorithm, magnetic field disturbances were visualized at distances up to ten times the size of the flaw. 相似文献
962.
963.
Luiza Carla Barbosa Martins Terezinha Maria Castro Della Lucia Wagner Gonzaga Gonçalves Jacques Hubert Charles Delabie José cola Zanuncio José Eduardo Serrão 《Microscopy research and technique》2015,78(7):603-612
Intramandibular glands have been poorly studied in polymorphic ants, where the differences between castes were unsufficiently scrutinized. Leaf‐cutting ants possess one of the most complex systems of communication and labor division, which is polymorphic well as age polyethism, and makes them an ideal model for the study of intramandibular glands. This study has investigated the occurrence of intramandibular glands in female castes and subcastes of Atta laevigata. The mandibles of the queen, medium, and minor workers, and soldiers were submitted to histological, histochemical, ultrastructural, and morphometric analyses. The class‐3 gland cells and the epidermal gland with a reservoir were found in all the castes. The queens and soldiers showed a higher number of class‐3 gland cells, distributed within the mandible as well as a greater gland size in comparison to the workers. The histochemical tests, periodic acid‐Schiff (PAS), mercury‐bromophenol, and Nile blue, were similar for the class‐3 gland cells and epidermal glands with a reservoir. However, the tests evidenced differences between the castes, with carbohydrates strongly positive in all of them, whereas neutral lipids were found in the queen and soldiers. The protein was weakly positive in the queen, whereas in the soldier, medium, and minor workers these reactions were strongly positive in the intramandibular glands. Our findings in A. laevigata suggest that intramandibular glands are directly involved in labor division and consequently in chemical communication between the castes. Microsc. Res. Tech. 78:603–612, 2015. © 2015 Wiley Periodicals, Inc. 相似文献
964.
Eduardo Kausel João Manuel de Oliveira Barbosa 《International journal for numerical methods in engineering》2012,90(3):343-352
This brief article outlines a new and rather simple method for obtaining the finite element matrices for a perfectly matched layer used for elastic wave propagation in the context of a frequency‐domain formulation. For this purpose, we introduce a fairly mild simplification, which allows applying the stretching functions directly to the mass and stiffness matrices obtained via conventional methods (i.e., elastic elements), a novel strategy that allows circumventing the use of integration via Gaussian quadrature. In essence, the technique proposed herein is equivalent to a direct application of the method of weighted residuals in stretched space, followed by a conversion of the linear dimensions into position‐dependent complex‐values. Most importantly, numerical tests demonstrate that the technique does work as intended, and in fact, splendidly so. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
965.
Emanuel Barbosa 《包装与设计》2010,(1):4-17
葡萄牙有着可追溯到史初的丰富文化,你可在受凯尔特人影响的多彩的北方民俗中、在源自摩尔人的法多音乐中、在高雅又富于浪漫气息的语言中、在独特的建筑中感受它丰富多彩的文化。葡萄牙语既是官方语言,同时也广为安哥拉、巴西、佛得角、东帝汶、几内亚比绍、莫桑比克、葡萄牙、澳门、圣多美和普林西人使用,它是世界上的主要语言之一, 相似文献
966.
Raquel Barbosa Queirós J. Paulo Noronha M. Goreti F. Sales Gerardo González Aguilar 《Advanced Engineering Materials》2010,12(5):B175-B178
The deterioration of water quality by Cyanobacteria cause outbreaks and epidemics associated with harmful diseases in Humans and animals because of the toxins that they release. Microcystin‐LR is one of the hepatotoxins most widely studied and the World Health Organization, recommend a maximum value of 1 µg L?1 in drinking water. Highly specific recognition molecules, such as molecular imprinted polymers are developed to quantify microcystins in waters for human use and shown to be of great potential in the analysis of these kinds of samples. The obtained results were auspicious, the detection limit found, 1.5 µg L?1, being of the same order of magnitude as the guideline limit recommended by the WHO. This technology is very promising because the sensors are stable and specific, and the technology is inexpensive and allows for rapid on‐site monitoring. 相似文献
967.
In this paper, a strategic location-allocation model is developed for the simultaneous design of forward and reverse supply chains. Strategic decisions such as network design are accounted for together with tactical decisions, namely, production, storage and distribution planning. The integration between strategic and tactical decisions is achieved by considering two interconnected time scales: a macro and a micro time. At macro level, the supply chain is designed in order to account for the existing demands and returns, whose satisfaction is planned simultaneously at the micro level where tactical decisions are taken. A Mixed Integer Linear Programming formulation is obtained which is solved to optimality using standard Branch & Bound techniques. Finally, the model accuracy and applicability is illustrated through the resolution of a case study. 相似文献
968.
Luciana A. Castillo Silvia E. Barbosa Numa J. Capiati 《Polymer Engineering and Science》2013,53(1):89-95
This article deals with the effects of surface‐modified talc particles on mechanical properties of polypropylene (PP)/talc composites. These materials were prepared by injection molding of PP blended with different concentrations of nontreated and treated talc, under the same processing conditions. Differential thermal calorimetry and scanning electron microscopy were used to assess thermal properties and morphology of the final composites. The reinforcing effect of talc, either treated or nontreated surface, on PP is analyzed through the tensile properties as a function of the mineral content (0–10 wt%). Morphological structure of composites revealed that the talc treatment improved the particle dispersion and distribution within the PP matrix and enhanced the interfacial PP‐talc adhesion. The mechanical properties of these composites, especially the Young modulus, tensile strength and elongation at break, were found to be improved respect to PP‐untreated talc ones. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers 相似文献
969.
Yanela Alonso Raquel E. Martini Antonio Iannoni Andrea Terenzi José M. Kenny Silvia E. Barbosa 《Polymer Engineering and Science》2015,55(5):1096-1103
The influence of sepiolite content (1, 2, and 3 wt%) and successive drawing steps on the final properties of polyethylene/sepiolite nanocomposite fibers are reported. Particularly the effects of these variables on crystallinity, fiber macroscopic morphology, and tensile mechanical properties are analyzed applying different experimental techniques: differential scanning calorimetry, wide angle x‐ray diffraction, scanning electronic microscopy, and tensile mechanical characterization. The study evidenced the important role of both sepiolite content and stretching on the crystalline morphology and mechanical properties of the nanocomposites fiber. Both variables favor the appearance of the monoclinic phase during polyethylene crystallization, and produce an increase of crystallinity degree (35 % with drawing steps and 10 % by the sepiolite incorporation in non drawing fiber). This change of crystal morphology influences mechanical properties enhancing with both sepiolite content and drawing steps. Thus, Young Modulus increases 17 times with drawing in pure PE fibers and 1.5 times because sepiolite presence. The strength shows similar behavior, but the elongation at break decreases 14 timed with draw steps and to a half by the sepiolite influence. The final properties of drawing nanocomposite fibers are so acceptable for textile applications and they content particles that enhance their moisture and odors absorptive capacities. POLYM. ENG. SCI., 55:1096–1103, 2015. © 2014 Society of Plastics Engineers 相似文献
970.
Karim Acuna‐Askar David Eduardo Pecina‐Chacon Marcela Mas‐Trevino Rolando Tijerina‐Menchaca Elba Guadalupe Rodriguez‐Perez Hugo Alberto Luna‐Olvera Jorge Angel Ascacio‐Martinez Hugo Alberto Barrera‐Saldana Juan Manuel Alfaro‐Barbosa 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2015,90(7):1253-1262