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排序方式: 共有1716条查询结果,搜索用时 31 毫秒
81.
Papagiannakis I. Klonidis D. Curri V. Poggiolini P. Bosco G. Killey R.I. Omella M. Prat J. Fonseca D. Teixeira A. Cartaxo A. Freund R. Grivas E. Bogris A. Birbas A.N. Tomkos I. 《Optoelectronics, IET》2009,3(2):73-85
The key design approaches and results in the field of compensation of optical impairment distortion by electronic means, as an outcome of the studies and research innovations developed within the joint project on mitigation of optical transmission impairments by electronic means work group of the ePhoton/ONet European project are presented. The research topics addressed are related to chromatic and polarisation mode dispersion, with particular reference to feed-forward/decision-feedback equaliser and maximum-likelihood sequence estimation-based equalisers as well as pre-distortion schemes. Additionally, the use of electronic compensation in metro/access applications is examined with reference to studies related to the performance enhancement of directly modulated laser transmitters, the compensation of the square-law characteristics of receivers and the equalisation of multi-level format schemes. 相似文献
82.
Luís A. F. Teixeira Matthew J. Grieshop Larry J. Gut 《Journal of chemical ecology》2010,36(10):1148-1154
The timing and duration of approaches by male peachtree borer Synanthedon exitiosa Say (Lepidoptera: Sesiidae) to commercial pheromone dispensers placed singly or at high density in peach orchards was determined
by using field-deployed video cameras and digital video recorders. Cameras were trained on one dispenser, and one standard
lure was placed in a peach orchard, and on 12 dispensers in a separate orchard where dispensers for mating disruption had
been placed at 371 per hectare. Male moth approaches were video recorded at the peak of peachtree borer annual flight, from
13 to 18 August 2009. The mean approach timing (h:min:sec±SD) during the study period was 11:33:12 ± 00:46:43, 11:43:52 ±
00:45:58, and 11:41:21 ± 00:45:54 AM with the single dispenser, high-density dispensers, and lure, respectively. Day-to-day
variability in approach timings suggested that there were no biologically significant differences among treatments. The frequency
distribution of approach durations varied among treatments, as the high-density dispensers had mostly short approaches, while
the distribution of approaches to the single dispenser and lure was wider. The median (interquartile range) approach duration
was 3 (2–4), 1 (1–2), and 4 (2–6) seconds with the single dispenser, high-density dispensers, and lure, respectively. The
relative rank of median approach durations was constant throughout the period, indicating differences among treatments. This
study showed that the presence of pheromone dispensers for mating disruption did not cause an advancement of peachtree borer
diel rhythm of response. Shorter approaches to dispensers placed at high density than singly suggest that dispenser retentiveness
is not constant with peachtree borer, which may bias estimates of disruption activity as a function of dispenser density. 相似文献
83.
84.
ABSTRACTFracture mechanics-based techniques have become very popular in the failure prediction of adhesive joints. The most commonly used is cohesive zone modeling (CZM). For both conventional fracture mechanics and CZM, the most important parameters are the tensile and shear critical strain energy release rates (GIC and GIIC, respectively). The most common tests to estimate GIC are the Double-Cantilever Beam (DCB) and the Tapered Double-Cantilever Beam (TDCB) tests. The main objective of this work is to compare the DCB and TDCB tests to obtain the GIC of adhesive joints. Three adhesives with varying ductilities were used to verify their influence on the precision of the typical methods of data reduction. For both tests, methods that do not need the measurement of crack length (a) were tested. A CZM analysis was considered to reproduce the experimental load–displacement (P-δ) curves and obtain the tensile CZM laws of each tested adhesive, to test the suitability of the data reduction methods, and to study the effect of the CZM parameters on the outcome of the simulations. The CZM models accurately reproduced the experimental tests and confirmed that the data reduction methods for the TDCB test tend to underestimate GIC for ductile adhesives. 相似文献
85.
S.A. Souza C.R.M. Afonso P.L. Ferrandini A.A. Coelho R. Caram 《Materials science & engineering. C, Materials for biological applications》2009,29(3):1023-1028
Titanium alloys present a combination of properties that makes them suitable materials for various medical applications, and there is special interest in Ti–Cu alloys for the fabrication of dental prostheses. The addition of Cu to Ti lowers the melting point of the alloy, as well as leading to the development of desirable mechanical properties. In this study a eutectoid alloy was prepared and heat treated, then cooled at various cooling rates. The eutectoid structure (α + Ti2Cu) was observed for all cooling rates used, and evidence of α′ martensite was found for cooling rate higher than 9 °C s–1. Lower cooling rates resulted in higher modulus values. This was attributed to the volume fraction of the α and Ti2Cu phases. Higher cooling rates produced structures with lower modulus values and greater hardness, a result attributed mainly to the development of a martensitic structure. 相似文献
86.
Amr Ahmed Andrew Arnold Luis Pedro Coelho Joshua Kangas Abdul-Saboor Sheikh Eric Xing William Cohen Robert F. Murphy 《Journal of Web Semantics》2010,8(2-3):151-154
The SLIF project combines text-mining and image processing to extract structured information from biomedical literature.SLIF extracts images and their captions from published papers. The captions are automatically parsed for relevant biological entities (protein and cell type names), while the images are classified according to their type (e.g., micrograph or gel). Fluorescence microscopy images are further processed and classified according to the depicted subcellular localization.The results of this process can be queried online using either a user-friendly web-interface or an XML-based web-service. As an alternative to the targeted query paradigm, SLIF also supports browsing the collection based on latent topic models which are derived from both the annotated text and the image data.The SLIF web application, as well as labeled datasets used for training system components, is publicly available at http://slif.cbi.cmu.edu. 相似文献
87.
B.L. Santos A.R. Silva B.P.S. Pitanga C.S. Sousa M.S. Grangeiro B.O. Fragomeni P.L.C. Coelho M.N. Oliveira N.J. Menezes-Filho M.F.D. Costa R.S. El-Bachá E.S. Velozo G.P. Sampaio S.M. Freire M. Tardy S.L. Costa 《Food chemistry》2011
In this study, we investigated the effects of the flavonoid rutin (3,3′,4′,5,7-pentahydroxyflavone-3-rutinoside) on glioma cells, using the highly proliferative human cell line GL-15 as a model. We observed that rutin (50–100 μM) reduced proliferation and viability of GL-15 cells, leading to decreased levels of ERK1/2 phosphorylation (P-ERK1/2) and accumulation of cells in the G2 phase of the cell cycle. On the other hand, 87.4% of GL-15 cells exposed to 100 μM rutin entered apoptosis, as revealed by flow cytometry after AnnexinV/PI staining. Nuclear condensation and DNA fragmentation were also observed, further confirming that apoptosis had occurred. Moreover, the remaining cells that were treated with 50 μM rutin presented a morphological pattern of astroglial differentiation in culture, characterised by a condensed cell body and thin processes with overexpression of GFAP. Because of its capacity to induce differentiation and apoptosis in cultured human glioblastoma cells, rutin could be considered as a potential candidate for malignant gliomas treatment. 相似文献
88.
Some qualitative and geometric aspects of 3-dimensional non-smooth vector fields theory are discussed. Our main aim is to study the dynamics near typical singularities of piecewise smooth dynamical systems, the so-called two-fold singularities. More specifically, we are interested in discussing stability problems of such systems around these singularities. 相似文献
89.
Héctor A. Ruiz Denise S. Ruzene Daniel P. Silva Mafalda A.C. Quintas António A. Vicente José A. Teixeira 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2011,86(1):88-94
BACKGROUND: Hydrothermal processes are an eco‐friendly processes that provide an interesting alternative for chemical utilization of lignocellulosic materials, in which water and crop residues are the only reagents. In this work the effect of process conditions (size distribution of the wheat straw, temperature and time) was evaluated against production of fermentable products. RESULTS: The use of milled wheat straw fractions as a raw material containing blends of different particle size distribution showed that the latter had an influence on the final sugars in the hydrolysate. Improved values of glucose (21.1%) and xylose yields (49.32%) present in the hydrolysate were obtained with treatment severity factors of 2.77 and 3.36, respectively. Mathematical models were developed aimed at establishing the effect of process conditions on monosaccharide concentration and its degradation in the liquor. CONCLUSION: This work shows that the use of wheat straw blends with various particle sizes has a significant effect on the extraction of fermentable products. The effect of treatment severity, which takes into account both processing time and temperature was also evaluated. These results are of importance for process design. Copyright © 2010 Society of Chemical Industry 相似文献
90.
Christiane Reis Fonseca José Luiz Paiva Eva Maria Rodriguez Fernando Juan Beltrán Antonio Carlos Silva Costa Teixeira 《臭氧:科学与工程》2017,39(4):255-263
The sugar industry is concerned with color formation due to the oxidation of phenolic compounds in the presence of carbohydrates. In this study, we investigated the ozonation of a mixture of five phenolic compounds in water and aqueous sucrose solution: p-coumaric (p-COU), caffeic (CAF), syringic (SYR), and chlorogenic (CHO) acids, as well as the flavonoid quercetin (QUE). The experiments were carried out in a 3-L glass reactor with magnetic stirring and a diffuser plate at the bottom to feed the ozone-oxygen gas mixture. Initial solution concentrations of 5 mg L?1 of each acid, 15 mg L?1 of quercetin, and 40 g L?1 of sucrose were used. The degradation of phenolic compounds followed apparent first-order kinetics, with rate constants and percent removals decreasing in the presence of sucrose. In water, average consumed ozone dosages of 10.4 and 18.7 mg L?1 were necessary for 50% and 90% removals, respectively, for CHO, CAF, and p-COU; for QUE they were slightly higher (13.9 and 20.5 mg L?1, respectively). At a consumed dosage of 20.8 mg O3 L?1, more than 99% removal was obtained for CHO, CAF, and p-COU, while 96.2% was achieved for SYR. In contrast, QUE revealed to be more recalcitrant during ozonation in the absence of sucrose, with only 70% removal at the highest consumed O3 dosage. The consumed ozone dosages for 50% and 90% removals were higher for CHO, CAF, and p-COU in aqueous sucrose solution, which may impact ozone consumption during real sugarcane juice treatment. Sucrose and t-butanol were the main influential parameters that significantly affected the total amount of phenolic compounds degraded. 相似文献