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101.
A simple analytical method for tracing rays in an optical system that is made up of spherical, cylindrical, and toric surfaces with an arbitrary rotation of its meridian plane with respect to the reference system is described. An analytical procedure is also given for obtaining the spot diagram on an arbitrarily oriented section, as well as for relating the diagram obtained for the plane of this section as a plane z = 0. Finally, as an application of this procedure, several graphic representations of the spot diagrams in the planes perpendicular or nonperpendicular to the axis are presented. 相似文献
102.
V. C. S. Reynoso L. C. Barbosa Yudong Liu O. L. Alves N. Aranha C. L. Cesar 《Journal of Materials Science》1995,30(24):6299-6302
We study the TiO2-BaO-ZnO-B2O3 glass system, where the ZnO and B2O3 compositions were constant and the ratio TiO2/BaO was varied from 0.87 to 1.76. A super kanthal resistance furnace was used to melt the compounds inside an alumina crucible, at 1200 °C, for 10 min. After melting, the glasses were poured out into steel moulds and rapidly cooled by quenching. The glasses obtained were homogeneous, bubble free and transparent. They were characterized by X-ray diffractometry, Fourier transform infrared spectroscopy (FTIR), UV-VIS spectroscopy, dilatometry, density and linear refractive index. An infrared cut off caused by the composition influence was found in both IR and UV-vis spectra. From dilatometry T
d and T
g were verified as being anomalous. The linear thermal expansion coefficient presented an anomalous behaviour in relation to TiO2 concentrations. The density and linear refractive index increased with increasing TiO2/BaO ratio arriving at their peak value of TiO2/BaO=1.5 and then decreasing. The dependence of softening point T
d on the ratio TiO2/BaO exhibited the same behaviour. It is suggested that Ti4+ plays a dual part in the glass system, assuming a predominantly tetrahedral coordination in the low titania region and a predominantly octahedral coordination in the high titania region. With a heat treatment of the glass around 600 °C, we observed a rapid change of refractive index with increasing temperature. 相似文献
103.
Higher incidence of Gastrospirillum sp. in swine with gastric ulcer of the pars oesophagea 总被引:1,自引:0,他引:1
AJ Barbosa JC Silva AM Nogueira E Paulino Júnior CR Miranda 《Canadian Metallurgical Quarterly》1995,32(2):134-139
Gastric ulcer in swine is characterized by an area of acid-peptic digestion, occurs usually in the pars oesophagea of the stomach, and has unknown etiopathogenesis. The present work was carried out to investigate the prevalence of the newly described spiral-shaped microorganism Gastrospirillum sp. ("Gastrospirillum suis") in stomachs of abattoir pigs with and without gastric ulcer. Stomachs were removed from 32 consecutive pigs presenting apparently normal mucosa and from 32 additional consecutive pigs presenting frank, chronic gastric ulcer of the pars oesophagea. Fragments of antral, oxyntic, cardiac and pars oesophagea regions were taken from each stomach and processed for histology and for identification of Gastrospirillum sp. in tissue sections. The microorganisms were identified mainly in the mucous layer and in gastric foveolas of the antral and oxyntic mucosa. Forty pigs (62.5%) were positive for Gastrospirillum sp.; among them, 27 (67.5%) had gastric ulcer, and 13 (32.5%) had no ulcer. Twenty-four pigs (37.5%) were negative for Gastrospirillum sp.; among them, five (20.8%) presented with gastric ulcer, and 19 (79.2%) had no ulcer. There was a significant difference between pigs with and without gastric ulcer in regard to the presence of Gastrospirillum sp. (P < 0.01). The spiral-shaped microorganism Gastrospirillum sp. that inhabits the stomach of pigs should be considered a possible factor connected with the etiopathogenesis of swine gastric ulcer. 相似文献
104.
Igor Garcia Ballhausen Sampaio José Viterbo Joris Guerin 《Computational Intelligence》2023,39(3):415-432
Object detection (OD) is used for visual quality control in factories. Images that compose training datasets are often collected directly from the production line and labeled with bounding boxes manually. Such data represent well the inference context but might lack diversity, implying a risk of overfitting. To address this issue, we propose a dataset construction method based on an automated pipeline, which receives a CAD model of an object and returns a set of realistic synthetic labeled images (code publicly available). Our approach can be easily used by non-expert users and is relevant for industrial applications, where CAD models are widely available. We performed experiments to compare the use of datasets obtained by the two different ways—collecting and labeling real images or applying the proposed automated pipeline—in the classification of five different industrial parts. To ensure that both approaches can be used without deep learning expertise, all training parameters were kept fixed during these experiments. In our results, both methods were successful for some objects but failed for others. However, we have shown that the combined use of real and synthetic images led to better results. This finding has the potential to make industrial OD models more robust to poor data collection and labeling errors, without increasing the difficulty of the training process. 相似文献
105.
Christopher Garcia 《工程优选》2016,48(9):1515-1528
This work studies a scheduling problem where each job must be either accepted and scheduled to complete within its specified due window, or rejected altogether. Each job has a certain processing time and contributes a certain profit if accepted or penalty cost if rejected. There is a set of renewable resources, and no resource limit can be exceeded at any time. Each job requires a certain amount of each resource when processed, and the objective is to maximize total profit. A mixed-integer programming formulation and three approximation algorithms are presented: a priority rule heuristic, an algorithm based on the metaheuristic for randomized priority search and an evolutionary algorithm. Computational experiments comparing these four solution methods were performed on a set of generated benchmark problems covering a wide range of problem characteristics. The evolutionary algorithm outperformed the other methods in most cases, often significantly, and never significantly underperformed any method. 相似文献
106.
107.
Marialucia Gallorini Viviana di Giacomo Valentina Di Valerio Monica Rapino Domenico Bosco Andrea Travan Mara Di Giulio Roberta Di Pietro Sergio Paoletti Amelia Cataldi Silvia Sancilio 《Journal of materials science. Materials in medicine》2016,27(12):186
Silver-based products have been proven to be effective in retarding and preventing bacterial growth since ancient times. In the field of restorative dentistry, the use of silver ions/nanoparticles has been explored to counteract bacterial infections, as silver can destroy bacterial cell walls by reacting with membrane proteins. However, it is also cytotoxic towards eukaryotic cells, which are capable of internalizing nanoparticles. In this work, we investigated the biological effects of Chitlac-nAg, a colloidal system based on a modified chitosan (Chitlac), administered for 24–48?h to a co-culture of primary human gingival fibroblasts and Streptococcus mitis in the presence of saliva, developed to mimic the microenvironment of the oral cavity. We sought to determine its efficiency to combat oral hygiene-related diseases without affecting eukaryotic cells. Cytotoxicity, reactive oxygen species production, apoptosis induction, nanoparticles uptake, and lysosome and autophagosome metabolism were evaluated. In vitro results show that Chitlac-nAg does not exert cytotoxic effects on human gingival fibroblasts, which seem to survive through a homoeostasis mechanism involving autophagy. That suggests that the novel biomaterial Chitlac-nAg could be a promising tool in the field of dentistry. 相似文献
108.
Emad Kassem Lorena Garcia Cucalon Eyad Masad Dallas Little 《International Journal of Pavement Engineering》2018,19(12):1111-1124
The quality of the interfacial bonding between asphalt binder and aggregates plays a significant role in determining the durability of asphalt mixtures. Warm mix asphalt (WMA) modifiers have been used extensively in the last decade primarily to reduce production and compaction temperatures as well as to improve workability of asphalt mixtures. This study aimed to provide better understanding of the effects of these WMA modifiers on the interfacial bonding between asphalt binders and aggregates. The evaluation focused on measuring surface energy of binders in unaged and aged states and aggregates and then calculating energy parameters that describe the potential of a given asphalt-aggregate combination to resist fatigue cracking and moisture damage. Results show that the combination of asphalt-WMA additive, as well as the content applied of WMA additive has a significant impact on the fatigue cracking and moisture damage resistance. The results suggest that it is poor practice to use a given type and percentage of WMA modifier without regard for binder type. Instead, test methods are recommended to evaluate the compatibility of asphalt binder, WMA additive type/content, and aggregates for improved performance at different conditions. 相似文献
109.
L. E. Murr E. P. Garcia E. T. Ferreyra C. -S. Niou J. M. Rivas S. A. Quiñones 《Journal of Materials Science》1996,31(22):5915-5932
Light and transmission electron microscopy techniques have been applied in observations of hypervelocity impact craters in two different copper targets: a 38 m grain size mill-processed target, and a 763 m grain size annealed target, the smaller grained target being impacted with a 1100 aluminium sphere and the larger grained target being impacted with a soda-lime glass sphere, at velocities near 6 km s–1. Both target craters exhibited dynamic recrystallization near the crater wall. The jetting associated with these two craters was very different. Considerably more plastic flow and a larger rim characterized the larger grained target. No significant melt-related phenomena were observed either near the crater wall or in the jetted rim for either crater. Consequently, the principal features of crater formation involve extreme plastic flow in the solid state. Microbands were observed to occur profusely in a zone below the smaller grained mill-processed target crater while more profuse and extremely long, unidirectional bundles of microbands (which were coincident with traces of {1 1 1} planes) occurred below the annealed larger grained target crater. These observations attest to the dominant and unique role played by deformation microbands in cratering in copper, because essentially no deformation twins were observed in either target. 相似文献
110.
F Devin P Garcia V Peyrot B Ridings JB Saracco 《Canadian Metallurgical Quarterly》1996,19(6-7):423-430
PURPOSE: The function of RPE is well known in PVR. Pharmacological agents have been extensively studied both experimentally and clinically. Few reports have detailed the interactions of antimitotic drugs on the microtubule network. The aim of this study is to visualize by indirect immunofluorescence the effects of colchicine and paclitaxel on the microtubule network of cultured pig RPE cells in interphase. METHODS: Pigs were killed at the slaughter-house, their eyes were enucleated. RPE cells were isolated and cultured. RPE cells were plated onto glass cover-slips at a density of 2,000,000 cells/ml, cultured and treated with the drugs during 4 and 24 hours at 37 degrees C at different concentrations. Immunofluorescence reaction was developped using antitubulin and fluoresceinated anti-mouse antibodies. The cytoskeletons were visualized employing a Zeiss photomicroscope equipped with epiilumination, a 63 x lens and appropriate filters for fluoresceine. RESULTS: The cytoplasmic microtubules of RPE cells were disrupted in a concentration and time-dependant manner by colchicine. Between 10 and 100 nm Veveral degrees of depolymarization of the microtubule network were observed. Paclitaxel between 1 micron and 10 microns was found to induce several degrees of microtubule "bundling" after 4 and 24 hours of incubation. Actin network was modified neither by colchicine and paclitaxel used in the same conditions. CONCLUSIONS: The results show that low doses of antimitotic drugs inhibit the microtubule network formation by depolymerization (colchicine) or stabilize it (paclitaxel). These actions inhibit cell division, which is one of the mechanisms implicated in PVR. 相似文献