检索结果-南通市图书馆

Fatigue Strength Evaluation of Resin-Injected Bolted Connections Using Statistical Analysis

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Engineering 2017年第6期3卷 795-805页

作者： Jose Antonio Fonseca de Oliveira Correia Bruno Alexandre Silva Pedrosa Patricia Cordeiro Raposo Abilio Manuel Pinho De Jesus Helena Maria dos Santos Gervisio Grzegorz Stanislaw Lesiukc Carlos Alberto da Silva Rebelo Rui Artur Bartolo Calcada luis Alberto Proenca Simoes da Silva Faculty of Engineering University of Porto Porto 4200-465 Portugal Institute for Sustainability and Innovation in Structural Engineering (ISISE) Department of Civil Engineering University of Coimbra Coimbra 3030-788 Portugal Department of Mechanics Materials Science and Engineering Faculty of Mechanical Engineering Wroclaw University of Technology Wroctaw 50-370 Poland

Different strategies can be used to perform reparations and reinforcements of ancient bolted and riveted metallic bridges. As the riveting process is not currently a common practice, it requires proper equipment and skilled workers. Another solution is the use of welding. However, the weldability of old steels is poor. Bolts are very attractive alternative solutions, and are most commonly used to repair old metallic bridges. Fitted bolts are expensive solutions; the alternative is the use of resin-injected bolts. The behavior of bolted joints with preloaded resin-injected bolts has been studied using quasi-static and creep tests; however, few studies on the slip and fatigue behavior of these joints can be found in the literature. This paper presents an overview of a few experimental programs that were carried out by several authors aiming at evaluating the fatigue behavior of single and double shear resin-injected bolted connections. A comparison between the experimental data of joints with preloaded standard bolts and preloaded resin- injected bolts shows a fatigue strength reduction in the latter. Since Eurocode 3 （EC3） suggests the same fatigue strength curve for joints made of resin-injected bolts and standard bolts, this may raise some con- cerns. Furthermore, research on the feasibility of using both bonded and bolted connections is shown. This last study was performed with high-strength low-alloy structural steel plates and an acrylic struc- tural adhesive for metal bonding. For both case studies, a statistical analysis is performed on fatigue experimental data using linearized boundaries and the Castillo and Fernandez-Canteli model. Fatigue design curves are proposed and compared with the design suggestions of several European and North American standards,

关键词： Fatigue Connections Structural reinforcements Structural adhesives S-N curves Resin-injected bolts

Strength and stiffness reduction factors for infilled frames with openings

在线全文

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2014年第3期13卷 437-454页

作者： luis D.Decanini Laura Liberatore Fabrizio Mollaioli Department of Structural Engineering and Geothecnics "Sapienza" University of Rome

Framed structures are usually infilled with masonry walls. They may cause a significant increase in both stiffness and strength, reducing the deformation demand and increasing the energy dissipation capacity of the system. On the other hand, irregular arrangements of the masonry panels may lead to the concentration of damage in some regions, with negative effects; for example soft story mechanisms and shear failures in short columns. Therefore, the presence ofinfill walls should not be neglected, especially in regions of moderate and high seismicity. To this aim, simple models are available for solid infills walls, such as the diagonal no-tension strut model, while infilled frames with openings have not been adequately investigated. In this study, the effect of openings on the strength and stiffness of infilled frames is investigated by means of about 150 experimental and numerical tests. The main parameters involved are identified and a simple model to take into account the openings in the infills is developed and compared with other models proposed by different researchers. The model, which is based on the use of strength and stiffness reduction factors, takes into account the opening dimensions and presence of reinforcing elements around the opening. An example of an application of the proposed reduction factors is also presented.

关键词： infilled frames openings strength stiffness reduction factor

Use of two-surfactants mixtures to attain specific HLB values for assisted TPH-diesel biodegradation

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2004年第6期16卷 950-956页

作者： luis G. Torres Neftalí Rojas Rosario Iturbe Instituto de Ingeniería Universidad Nacional Autó noma de México Coordinación de Ingeniería Ambiental Grupo Saneamiento de Suelos y Acuíferos Apartado Postal 70-472 Coyoacán 04510 México D.F. Mexico

In a surfactant assisted biodegradation process, the choice of surfactant(s) is of crucial importance. The question is: does the type of surfactant(i.e. chemical family) affect the biodegradation process at fixed hidrophillic-lypofillic balance(HLB) values? Microcosm assessments were developed using contaminated soil, with around of 5000 mg/kg of hydrocarbons as TPH-diesel. Mixtures of three nonionic surfactants were employed to get a wide range of specific HLB values. Tween20 and Span20 were mixed in the appropriate proportions to get HLB values between 8.6 and 16.7. Tween/Span60 mixtures reached HLB values between 4.7 and 14.9. Finally, Tween/Span80 combinations yielded HLB values between 4.3 and 15. TPH-diesel biodegradation was measured at the beginning, and after 8 weeks, as well as the FCU/gr soil, as a measure of microorganisms′ development during the biodegradation period. A second aim of this work was to assess the use of guar gum as a biodegradation enhancer instead of synthetic products. The conclusions of this work are that surfactant chemical family, and not only the HLB value clearly affects the assisted biodegradation rate. Surfactant's synergism was clearly observed. Regarding the use of guar gum, no biodegradation enhancement was observed for the three assessed concentrations, i.e., 2, 20, and 200 mg/kg, respectively. On the contrary, TPH-diesel removal was lower as the gum concentration increased. It is quite possible that guar gum was used as a microbial substrate.

关键词： aged soils enhanced bioremediation HLB mixtures Tween Span surfactants

Extracellular green synthesis of silver nanoparticles using Amazonian fruit Araza(Eugenia stipitata McVaugh)

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2016年第9期26卷 2363-2371页

作者： Brajesh KUMAR Kumari SMITA Alexis DEBUT luis CUMBAL Centro de Nanociencia y Nanotecnologia Universidad de las Fuerzas Armadas ESPE Department of Chemistry TATA College Kolhan UniversityChaibasa- 833202 Jharkhand India

An eco-friendly method for the extracellular synthesis of silver nanoparticles（AgNPs） using aqueous Araza fruit extract and their antioxidant activity was investigated. It was observed that UV–Vis absorption peak is dependent on various parameters such as pH, temperature, and change of time. The initial appearance of the yellow color with intense surface plasmon bands at 430-450 nm, then transmission electron microscopy, scanning electron microscopy and X-ray diffraction analysis revealed the formation of 15-45 nm sized, spherical and crystalline Ag NPs. Fourier transform infrared spectroscopy depicted that malic acid, citric acid, and carotenoids of Araza fruit involved in the synthesis of Ag NPs. In addition, the surface modified AgNPs（77.42%, 1mL） showed nearly double antioxidant efficiency than Araza fruit extract（35.30%, 1 mL） against 1, 1-diphenyl-2-picrylhydrazyl. The present study highlights the possibility of using the Araza fruit to synthesize AgNPs, which could be used effectively in the present and future antioxidant agent.

关键词： extracellular synthesis silver nanoparticles antioxidant eco-friendliness

Different risk factors influence peptic ulcer disease development in a Brazilian population

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2012年第38期18卷 5404-5411页

作者： Rodrigo Buzinaro Suzuki Rodrigo Faria Cola Larissa Tranquilino Bardela Cola Camila Garcia Ferrari Fred Ellinger Altino Luiz Therezo luis Carlos da Silva André Eterovic Márcia Aparecida Sperana Department of Genotyping Hemocenter Marilia Medical School Marilia 17519-030 So Paulo Brazil Center for Natural and Human Sciences Universidade Federal do ABC Santo André 09210-170 So Paulo Brazil Department of Molecular Biology Marilia Medical School Marilia 17519-030 So Paulo Brazil Department of Pathology Marilia Medical School Marilia 17519-030 So Paulo Brazil

AIM: To investigate age, sex, histopathology and Helicobacter pylori (H. pylori) status, as risk factors for gastroduodenal disease outcome in Brazilian dyspeptic *** submitted to upper gastroscopy at Hospital das Clinicas of Marilia, antral biopsy specimens were obtained and subjected to histopathology and H. pylori diagnosis. All patients presenting chronic gastritis (CG) and peptic ulcer (PU) disease localized in the stomach, gastric ulcer (GU) and/or duodenal ulcer (DU) were included in the study. Gastric biopsies (n = 668) positive for H. pylori by rapid urease test were investigated for vacuolating cytotoxin A (vacA ) medium (m) region mosaicism by polymerase chain reaction. Logistic regression analysis was performed to verify the association of age, sex, histopathologic alterations, H. pylori diagnosis and vacA m region mosaicism with the incidence of DU, GU and CG in patients. RESULTS: Of 1466 patients submitted to endoscopy, 1060 (72.3%) presented CG [male/female = 506/554; mean age (year) ± SD = 51.2 ± 17.81], 88 (6.0%) presented DU [male/female = 54/34; mean age (year) ± SD = 51.4 ± 17.14], and 75 (5.1%) presented GU [male/female = 54/21; mean age (year) ± SD = 51.3 ± 17.12] and were included in the comparative analysis. Sex and age showed no detectable effect on CG incidence (overall c 2 = 2.1, P = 0.3423). Sex [Odds ratios (OR) = 1.8631, P = 0.0058] but not age (OR = 0.9929, P = 0.2699) was associated with DU and both parameters had a highly significant effect on GU (overall c 2 = 30.5, P < 0.0001). The histopathological results showed a significant contribution of ageing for both atrophy (OR = 1.0297, P < 0.0001) and intestinal metaplasia (OR = 1.0520, P < 0.0001). Presence of H. pylori was significantly associated with decreasing age (OR = 0.9827, P < 0.0001) and with the incidence of DU (OR = 3.6077, P < 0.0001). The prevalence of m1 in DU was statistically significant (OR = 2.3563, P = 0.0018) but not in CG (OR = 2.678, P = 0.0863) and G

关键词： Helicobacter pylori Gastric ulcer disease Duodenal ulcer disease Gastric atrophy Helicobacter pylori vacuolating cytotoxin A medium region mosaicism

Fully reversible spectral compression of arbitrary pulsed data signals

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Photonics Research 2020年第5期8卷 659-670页

作者： luis ROMERO CORTéS REZA MARAM JOSéAZANA Institut National de la Recherche Scientifique–énergie Matériaux et Télécommunications(INRS–EMT)H5A 1K6 MontrealQuebecCanada

data signals consisting of arbitrarily modulated sequences of pulses are extensively used for processing and communication *** spectral extent of such signals is determined by the bandwidth of the individual pulses in the sequence,which imposes a fundamental limit to the maximum amount of information that can be transmitted or processed per time *** this work,we propose and experimentally demonstrate that the frequency spectrum occupied by a data-modulated pulse sequence can be significantly compressed to well below the individual pulse bandwidth while still maintaining the temporal duration of the pulses in the sequence and without losing any of the information carried by the *** proposed method involves fully reversible linear transformations of the data signal along the time and frequency *** demonstrate successful pulse-shapepreserving spectral compression and subsequent full waveform and information recovery of a^10 Gb/s optical pulse sequence,modulated by an arbitrary data pattern,liberating over 60%of its *** findings should prove useful for applications in signal processing,communications,and others.

关键词： spectral preserving pulsed

Height-to-diameter ratios with temporal and dendro/morphometric variables for Brazilian pine in south Brazil

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Research 2021年第1期32卷 191-202页

作者： Andre Felipe Hess Myrcia Minatti Emanuel Arnoni Costa luis Paulo Baldissera Schorr Gabriel Teixeira da Rosa Isadora de Arruda Souza Geedre Adriano Borsoi Veraldo Liesenberg Thiago Floriani Stepka Roberta Abatti Department of Forest Engineering Santa Catarina State University2090 Luiz de Camoes AvenueLagesSanta Catarina State 88520-000Brazil Department of Forest Engineering Federal University of Parana(UFPR)Pref.Lothario Meissner Ave.900CuritibaParana 80060-000Brazil

Height-to-diameter ratios(HD)are an important measure of the stability,density and competition of forest *** refl ects the vertical growth of the trees,the vulnerability of the forest canopy structure and infl uences volumetric *** ratios vary according to tree size,availability of resources for growth,stand density and species *** were taken from 210 trees and a regression technique of generalized linear models for the HD ratio applicable for forest structure conservation was *** objective of this study was to model the HD ratios of dominant and co-dominant trees of Araucaria angustifolia according to morphometric,dendrometric,annual diameter increment,stand density,and age variables in three sites in southern *** results show that the HD ratio decreases with increasing age,crown area and basal area,and increases with stand density and annual diameter *** of the developed equations was demonstrated by the values of deviation,Bayesian and Akaike *** results are of interest to forest managers since they make decisions about silvicultural *** continuity and forest production indicate that any intervention should be directed at younger trees of smaller sizes,and that one of the main management factors for stand stability and growth is the formation of the stand and its capture of light.

关键词： Forest management Mixed forests Conservation Araucaria angustifolia

北开普地区立法机构综合体,金伯利省,北开普地区,南非

在线全文

学校读者我要写书评

暂无评论

世界建筑 2005年第2期 62-65页

作者： luis Ferreira da Silva Architects 路易斯.弗瑞拉.达.西尔瓦建筑事务所

这是南非金伯利北角的立法机构建筑群。是当地省政府即将进入的新办公地点，包括辩论室、总理办公室，立法委员会委员办公室发言人办公室、厨房、自助餐厅、餐馆、政府办公室、会议中心、媒体事务办公室、图书馆和档案办公室。

关键词：立法机构南非综合体金办公室会议中心省政府建筑群委员会

Multiple intrahepatic pseudocysts in acute pancreatitis

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2007年第34期13卷 4655-4657页

作者： david Casado luis Sabater Julio Calvete Empar Mayordomo luis Aparisi Juan Sastre Salvador Lledo Department of Surgery Liver Biliary and Pancreatic Unit University of Valencia Spain Department of Pathology University of Valencia Spain Laboratory of Pancreatic Function Hospital Clinic University of Valencia Spain Department of Physiology University of Valencia Spain

Liver pseudocysts are a very rare complication in acute pancreatitis with only a few cases previously described. The lack of experience and literature on this condition leads to difficulties in the differential diagnosis and management. We report herein a case of acute pancreatitis who developed multiple intrahepatic pseudocysts. After complete imaging evaluation, the diagnosis was still unclear and the patient was operated on. The presence of liver lesions in patients with acute pancreatitis should raise the possibility of intrahepatic pseudocysts.

关键词： Pancreatic pseudocyst Liver pseudocyst Intrahepatic pseudocyst