检索结果-南通市图书馆

Journal of Materials Science & Technology 2018年第1期34卷 119-127页

作者： Alessandro Barbini Jan Carstensen Jorge f.dos santos Helmholtz-Zentrum Geesthacht Institute of Materials Research Materials Mechanics Solid-State Joining Processes (WMP)

friction stir welding （fSW） and stationary shoulder friction stir welding （SSfSW） were carried out for the butt joining of dissimilar AA2024-T3 and AA7050-T7651 aluminium alloys with thicknesses of 2 mm. A comparison between the two processes was performed by varying the welding speed while keeping the rotational speed constant, Through the analysis of the force and torque produced during welding and a simple analytical model, it was possible to show that in SSfSW there is more effective coupling with the tool and the heat produced is more efficiently distributed. This process decreases both the welding area and the diffusion at the interface of the two alloys compared with fSW. The minimum microhardness occurred at the advancing side （AS） at the interface between the thermo-mechanically affected zone （TMAZ） and the stir zone （SZ） in both processes, although the decrease was more gradual in SSfSW. This interface is also where all specimens failed for both welding technologies. An increase in tensile strength was measured in SSfSW compared with standard fSW. furthermore, it was possible to establish the mechanical performance of the material in the fracture zone using digital image correlation.

关键词： Stationary shoulder friction stir welding friction stir welding Dissimilar welded joints Process analysis Microstructure analysis Mechanical behaviour

Effects of porosity,dry unit weight,cement content and void/cement ratio on unconfined compressive strength of roof tile waste-silty soil mixtures

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2019年第2期11卷 369-378页

作者： Eclesielter Batista moreira Jair Arrieta Baldovino Juliana Lundgren Rose Ronaldo Luis dos santos Izzo Department of Civil Construction Federal University of Technology e ParanaCampus Curitiba

One of the conventional ways to improve the mechanical behavior of soils is to mix them with cementing agents such as cement, lime and fly ash. Recently, introduction to alternative materials or sub-products that can be adopted to improve the soil strength is of paramount importance. Therefore, the present study aims to investigate the effects of porosity(h), dry unit weight(gd) of molding, cement content(C)and porosity/volumetric cement content ratio(h/Civ) or void/cement ratio on the unconfined compressive strength(quor UCS) of silty soileroof tile waste(RT) mixtures. Soil samples are molded into four different dry unit weights(i.e. 13 kN/m^3, 13.67 kN/m^3, 14.33 kN/m^3 and 15 kN/m^3) using 3%, 6% and 9%cement and 5%, 15% and 30% RT. The results show that with the addition of cement, the strength of the RT esoil mixtures increases in a linear manner. On the other hand, the addition of RT decreases quof the samples at a constant percentage of cement, and the decrease in porosity can increase qu. A dosage equation is derived from the experimental data using the porosity/volumetric cement content ratio(h/C_(iv)) where the control variables are the moisture content, crushed tile content, cement content and porosity.

关键词： Roof tile waste (RT) Voids/cement ratio Reuse Ground improvement

Optimizing the evolution of strength for lime-stabilized rammed soil

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2019年第4期11卷 882-891页

作者： Jair de Jesus Arrieta Baldovino Ronaldo Luis dos santos Izzo Eclesielter Batista moreira Juliana Lundgren Rose Department of Civil Construction Federal University of Technology-Parana

In the present study,unconfined compressive strength(qu)values of two lime-treated soils(soil 1 and 2)with curing times of 28 d,90 d and 360 d were *** influence of void/lime ratio was represented by the porosity/volumetric lime content ratio(η/Liv)as the main parameter.η/Liv represents the volume of void influenced by compaction effort and lime *** evolution of qu was analyzed for each soil using the coefficient of determination as the optimization *** at providing adjustments to the mechanical resistance values,the η/Liv parameter was modified to η/LivC using the adjustment exponent C(to make qu-η/Liv variation rates compatible).The results show that with the decrease of η/*** increases potentially and the optimized values of C were *** mechanical resistance data show similar trends between qu and η/LivC for the studied silty soil-ground lime mixtures,which were cured at ambient temperature(23±2)℃ with different curing times of 28-360 ***,optimized equations were presented using the normalized strengths and the proposed optimization model,which show 6% error and 95% acceptability on average.

关键词： Lime-treated soil Void/lime ratio Ground improvement

Assessing the Bonding Interface Characteristics and Mechanical Properties of Bobbin Tool friction Stir Welded Dissimilar Aluminum Alloy Joints

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2021年第1期34卷 125-134页

作者： Quan Wen Wenya Li Vivek Patel Luciano Bergmann Benjamin Klusemann Jorge f.dos santos State Key Laboratory of Solidifi cation Processing Shaanxi Key Laboratory of Friction Welding TechnologiesNorthwestern Polytechnical UniversityXi’an 710072China Institute of Materials Research Materials MechanicsSolid-State Joining ProcessesHelmholtz-Zentrum GeesthachtMax-Planck-Straße 121502 GeesthachtGermany Institute of Product and Process Innovation Leuphana University of LüneburgUniversitätsallee 121335 LüneburgGermany

This study focuses on the bonding interface characteristics and mechanical properties of the bobbin tool friction stir welded dissimilar AA6056 and AA2219 aluminum alloy joints using diff erent welding *** arise solely in the stir zone at the AA2219 side.A distinct boundary with limited material mixing develops at the middle section of the bonding interface,while excellent material mixing with an irregularly jagged pattern forms at the top and bottom sections of the bonding *** the welding speed,the material mixing is rarely changed at the middle section in comparison with the bottom ***,a small diff erence between Guinier–Preston dissolution and Q phase precipitation leads to rare change of hardness in the heat aff ected zone(HAZ)at the AA6056 *** increased hardness of the HAZ at the AA2219 side is attributed to avoidance of the dissolution ofθ’’phase precipitates.A maximum tensile strength of 181 MPa is obtained at 300 mm *** occur at the AA6056 side near the top and bottom surfaces and at the bonding interface in the middle section of the *** regions close to the top and bottom surfaces of the joints show a better ductility.

关键词： Bobbin tool friction stir welding Dissimilar aluminum alloy Bonding interface Precipitation Mechanical property

Inherited fanconi syndrome

在线全文

学校读者我要写书评

暂无评论

World Journal of Pediatrics 2023年第7期19卷 619-634页

作者： Anna Luiza Braga Albuquerque Rafael dos santos Borges Ana flavia Conegundes Erika Emmylaine dos santos frederico moreira Man fu Clara Tavares Araujo Pedro Alves Soares Vaz de Castrol Ana Cristina Simoes e Silva Interdisciplinary Laboratory of Medical Investigation Unit of Pediatric NephrologyFaculty of MedicineFederal University of Minas Gerais(UFMG)Belo HorizonteBrazil Department of Pediatrics Faculty of MedicineUFMGAlfredo Balena Avenue1902Nd FloorRoom#281Belo HorizonteMG 30130-100Brazil

Background fanconi-Debré-de Toni syndrome(also known as fanconi renotubular syndrome,or fRST)profoundly increased the understanding of the functions of the proximal convoluted tubule(PCT)and provided important insights into the pathophysiology of several kidney diseases and drug *** sources We searched Pubmed and Scopus databases to find relevant articles about *** review article focuses on the physiology of the PCT,as well as on the physiopathology of fRST in children,its diagnosis,and *** fRST encompasses a wide variety of inherited and acquired PCT alterations that lead to impairment of PCT *** children,fRST often presents as a secondary feature of systemic disorders that impair energy supply,such as Lowe's syndrome,Dent's disease,cystinosis,hereditary fructose intolerance,galactosemia,tyrosinemia,Alport syndrome,and Wilson's *** rare,congenital causes of fRST greatly impact the morbidity and mortality of patients and impose diagnostic ***,its treatment is diverse and considers the ability of the clinician to identify the correct etiology of the *** The early diagnosis and treatment of pediatric patients with fRST improve the prognosis and the quality of life.

关键词： Cystinosis fanconi syndrome fanconi renotubular syndrome fanconi-Debre-de Toni syndrome Proximal tubule Renal tubular transport-Rickets

Capacitorless Solid-state Power filter for Single-phase DC-AC Converters

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

CES Transactions on Electrical Machines and Systems 2024年第3期8卷 367-377页

作者： Haitham Kanakri Euzeli C.dos santos Purdue University Electrical and Computer Engineering DepartmentIndianapolisIN46202 USA

Converters rely on passive filtering as a crucial element due to the high-frequency operational characteristics of power *** filtering methods involve a dual inductor-capacitor(LC)cell or an inductor-capacitor-inductor(LCL)***,capacitors are susceptible to wear-out mechanisms and failure ***,the necessity for monitoring and regular replacement adds to an elevated cost of ownership for such *** utilization of an active output power filter can be used to diminish the dimensions of the LC filter and the electrolytic dc-link capacitor,even though the inclusion of capacitors remains an indispensable part of the *** paper introduces capacitorless solid-state power filter(SSPf)for single-phase dc-ac *** proposed configuration is capable of generating a sinusoidal ac voltage without relying on *** proposed filter,composed of a planar transformer and an H-bridge converter operating at high frequency,injects voltage harmonics to attain a sinusoidal output *** design parameters of the planar transformer are incorporated,and the impact of magnetizing and leakage inductances on the operation of the SSPf is *** analysis,supported by simulation and experimental results,are provided for a design example for a single-phase *** total harmonic distortion observed in the output voltage is well below the IEEE 519 *** system operation is experimentally tested under both steady-state and dynamic conditions.A comparison with existing technology is presented,demonstrating that the proposed topology reduces the passive components used for filtering.

关键词： Solid-state power filter(SSPf) Capacitorless topology Active output power filter(AOf) Planar transformer Electrolytic capacitor Lifetime Wear-out mechanisms

Pharmacological therapy used in the elimination of Helicobacter pylori infection:A review

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2015年第1期21卷 139-154页

作者： Ariolana A dos santos Adriana A Carvalho Department of Pharmacy Federal University of SergipeCampus Lagarto49400-00 LagartoSergipeBrazil

The optimal therapy for Helicobacter pylori(***) infection should combine a high cure rate and a short treatment duration with a favorable side-effect profile and should maintain a low *** strategies have been proposed to increase the *** eradication rate,including the extension of the treatment duration to 14 d,the use of a four-drug regimen(quadruple,sequential,and concomitant treatments),and the use of novel antibiotics,such as ***,triple therapy remains the most widely accepted firstline treatment regimen in Brazil and the United Statesand throughout *** this therapy is limited by resistance to clarithromycin,other therapeutic regimens have been investigated *** review describes the current literature involving studies directly comparing these different therapies and their efficacies.

关键词： Clarithromycin resistant Helicobacter pylori Pepti

Can small-scale altitudinal gradients predict spatial and temporal patterns in tropical forests?

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

Journal of forestry Research 2021年第5期32卷 1854-1865页

作者： Mariana Caroline moreira Morelli Cléber Rodrigo de Souza Jean Daniel Morel Vinícius Andrade Maia Alisson Borges Miranda santos Kaline fernandes Miranda Rubens Manoel dos santos forest Sciences Department Federal University of LavrasCampus UniversitárioCx.P.3037LavrasMGCEP 37200-000Brazil Department of Biology Federal University of LavrasCampus UniversitárioLavrasMGCEP 37200-000Brazil

In tropical montane forests,compositional and structural changes are commonly driven by broad-scale altitudinal ***,given the lack of knowledge on small-scale vegetation changes and temporal dynamics,we address the effects of small-scale variations in soil and altitude on tree community structure,temporal dynamics and phylogenetic diversity in a semi-deciduous tropical forest of the Atlantic forest Domain,southeastern *** 2010 and 2015 we sampled thirty plots of 400 m^(2),set up along an altitudinal gradient between 1000 and 1500 m a.s.I..In each plot,we collected soil samples for chemical and textural *** fitted linear models to test the effects of altitude and soil on community dynamics and phylogenetic *** and soil explained the spatial variation in number of individuals and phylogenetic diversity *** lower to higher altitudes,we found decreasing fertility,increasing tree density and decreasing phylogenetic *** significantly influenced the increases in total biomass(from 240.9 to 255.4 t ha^(-1))and individual biomass(from 0.15 to 0.17 t)recorded in the *** while community temporal dynamics had rates of 1.96%for mortality,1.02%for recruitment,1.61%for biomass loss and 2.81%for biomass gain,none of them were explained by altitude or *** species substitution averaged0.1 in the ***,these results suggest that the small-scale variations in altitude and soil likely determine the conditions and resources that drive community assembly and structure,which are expressed by spatial variations along the altitudinal *** the same time,temporal patterns were not influenced by altitude-related environmental variation,resulting in a similar dynamic behaviour across the gradient,suggesting that broad-scale factors may play a more important role than local ones.

关键词： fine-scale Semideciduous forests Montane forests Dynamic patterns

Saturated anisotropic hydraulic conductivity of a compacted lateritic soil

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2018年第5期10卷 986-991页

作者： Roberto Aguiar dos santos Edmundo Rogerio Esquivel Varzea Grande Institute of Engineering federal University of Mato Grosso Cuiaba Mato Grosso Brazil Sao Carlos School of Engineering University of Sao Paulo Sao Carlos Sao Paulo Brazil

This study focuses on the saturated anisotropic hydraulic conductivity of a compacted lateritic clayey sandy soil. The effects of the molding water content and the confining stress on the anisotropic hydraulic conductivity are investigated. The hydraulic conductivity is measured with a flexible-wall permeameter. Samples are dynamically compacted into the three compaction states of a standard Proctor compaction curve： the dry branch, optimum water content and wet branch. Depending on the molding water content and confining stress, the hydraulic conductivity may increase or decrease. In addition, the results indicate that, when the samples are compacted to the optimum water content, lower hydraulic conductivity is obtained, except at a confining stress equal to 50 kPa. The increase of the confining stress decreases the hydraulic conductivity for each of the evaluated compaction states. In the wet branch, horizontal hy- draulic conductivity is about 8 times higher than the vertical value. The anisotropic hydraulic conduc- tivities of the dry and wet branches decrease when the confining stress increases, and the opposite is observed in the optimum water content state.

关键词： Hydraulic conductivity Anisotropic behavior Lateritic soil Tropical soil Compacted soil

Improving weld formability by a novel dual-rotation bobbin tool friction stir welding

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2018年第1期34卷 135-139页

作者： f.f.Wang W.Y.Li J.Shen Q.Wen J.f.dos santos State Key Laboratory of Solidification Processing Shaanxi Key Laboratory of Friction Welding Technologies Northwestern Polytechnical University Helmholtz-Zentrum Geesthacht Institute of Materials Research Materials Mechanics China Academy of Launch Vehicle Technology Beijing Institute of Astronautical Systems Engineering

A novel dual-rotation bobbin tool friction stir welding （DBT-fSW） was developed, in which the upper shoulder （US） and lower shoulder （LS） have different rotational speeds. This process was tried to weld 3.2 mm thick alunlinum-lithium alloy sheets. The metallographic analysis and torque measurement were carried out to characterize the weld formabiliW. Experimental results show that compared to conven- tional bobbin tool friction stir welding, the DBT-fSW has an excellent process stability, and can produce the defect-free joints in a wider range of welding parameters. These can be attributed to the significant improvement of material flow caused by the formation of a staggered layer structure and the unbalanced force between the US and LS during the DBT-fSW process.

关键词： Bobbin tool friction stir welding Dual rotation Material flow Microstructure Microhardness