Avaliação de ligações K e T entre perfis estruturais tubulares circulares.

O difundido uso de perfis estruturais tubulares, principalmente devido às vantagens associadas ao comportamento estrutural e estético, levou a uma intensa utilização nos países da Europa, Sudeste Asiático, América do Norte e na Austrália. Países como Canadá, Inglaterra, Alemanha e Holanda fazem uso intensivo dessas estruturas e contam com uma produção corrente, industrializada e contínua com alto grau de desenvolvimento tecnológico. O aumento da oferta deste tipo de perfis, aliado a recentes pesquisas nesta área, leva o Brasil a se inserir neste cenário mundial. Entretanto, as normas brasileiras que regem o dimensionamento destes perfis ainda não se encontram atualizadas, principalmente no que tange ao dimensionamento de ligações de perfis tubulares. Considerando esta perspectiva, este trabalho apresenta uma análise de ligações tipo K e T com perfis tubulares circulares (CHS). Propõe-se estabelecer um quadro comparativo entre as formulações analíticas de dimensionamento proposta pelo Eurocode 3 Parte 1.8, 2 edição do guia de projeto de ligações tubulares do CIDECT, projeto de norma brasileira PN 02.125.03-004 e critérios de deformação limite. Para cada um dos tipos de ligações analisadas, desenvolveu-se um modelo em elementos finitos no programa Ansys, calibrado e validado com resultados experimentais e numéricos existentes na literatura. As não-linearidades física e geométrica foram incorporadas aos modelos, a fim de se mobilizar totalmente a capacidade resistente da ligação. A não-linearidade do material foi considerada através do critério de plastificação de Von Mises através de uma lei constitutiva tensão versus deformação bilinear. A não-linearidade geométrica foi introduzida no modelo através da Formulação de Lagrange Atualizado considerando-se a previsão de grandes deformações de forma a permitir a redistribuição de carregamento na ligação após o escoamento inicial. Esta dissertação propõe ainda, a modelagem de uma treliça planar constituída de perfis tubulares, objetivando estabelecer uma comparação entre um nó isolado e um nó da treliça planar.

Avaliação de ligações KK entre perfis tubulares em aço.

Em virtude do elevado grau de desenvolvimento da tecnologia em sua produção, a utilização de perfis tubulares é grandemente difundida em países como, por exemplo, Canadá, Inglaterra, Alemanha e Holanda. A utilização de tais perfis no Brasil era bastante restrita, limitando-se a coberturas espaciais. Atualmente, a situação do mercado brasileiro começa a se alterar em decorrência do significativo aumento da oferta de perfis tubulares estruturais. Este trabalho apresenta uma análise de ligações tipo KK com perfis tubulares circulares (CHS), com o intuito de estabelecer um quadro comparativo entre as formulações analíticas de dimensionamento proposta pelo Eurocode 3 Parte 1.8, 2 edição do guia de projeto de ligações tubulares do CIDECT, ABNT NBR 16239:2013, pelas equações propostas por Paul e Kurobane e critérios de deformação limite. A calibração de um modelo foi feita com dados numéricos e experimentais. Para cada um dos tipos de ligações analisadas, desenvolveu-se um modelo em elementos finitos no programa Ansys. As não-linearidades física e geométrica foram incorporadas aos modelos, a fim de se mobilizar totalmente a capacidade resistente da ligação. A não-linearidade do material foi considerada com o uso do critério de plastificação de Von Mises através de uma lei constitutiva tensão versus deformação bilinear. A não-linearidade geométrica foi introduzida no modelo através da Formulação de Lagrange Atualizado considerando-se a previsão de grandes deformações de forma a permitir a redistribuição de carregamento na ligação após o escoamento inicial. Foi proposto um modelo de uma treliça espacial composta por perfis tubulares de seção circular para comparar os resultados de análises de uma ligação isolada e a resposta desta mesma ligação como parte de uma treliça em escala real.

Avaliação da satisfação sexual em pacientes com endometriose infiltrativa profunda

A endometriose é uma doença benigna que causa dor e infertilidade. As disfunções sexuais são frequentes, especialmente a dispareunia de profundidade, interferindo na qualidade de vida e particularmente na vida conjugal dessas pacientes. O objetivo deste trabalho foi avaliar a satisfação sexual de pacientes com endometriose infiltrativa profunda. Foram analisadas cinquenta e sete pacientes com diagnóstico de endometriose infiltrativa profunda acompanhadas no Hospital Universitário Pedro Ernesto (HUPE) de julho de 2010 a dezembro de 2011. O grupo controle incluiu 38 pacientes saudáveis do ambulatório de planejamento familiar do HUPE. Foi aplicado o Female Sexual Function Index (FSFI), questionário validado para avaliação funcional da atividade sexual. Em relação ao resultados não houve diferença estatisticamente significativa no escore total do FSFI entre os dois grupos. No domínio dor, as pacientes com endometriose apresentaram escores significativamente menores, ou seja, maior intensidade de dor, do que o grupo controle. O resultado deste estudo sugere que as pacientes com endometriose apresentam um comprometimento do domínio dor, sem prejuízo potencial da função sexual global.

THEORETICAL ROAD DAMAGE DUE TO DYNAMIC TYRE FORCES OF HEAVY VEHICLES. PART 1: DYNAMIC ANALYSIS OF VEHICLES AND ROAD SURFACES.

Theory is presented for simulating the dynamic wheel forces generated by heavy road vehicles and the resulting dynamic response of road surfaces to these loads. Sample calculations are provided and the vehicle simulation is validated with data from full-scale tests. The methods are used in the accompanying paper to simulate the road damage done by a tandem-axle vehicle.

Implementation of semi-active damping on a tri-axle heavy-vehicle suspension

A semi-active truck damper was developed in conjunction with a commercial shock absorber manufacturer. A linearized damper model was developed for control system design purposes. Open- and closed-loop damper force tracking control was implemented, with tests showing that an open-loop approach gave the best compromise between response speed and accuracy. A hardware-in-the-loop test facility was used to investigate performance of the damper when combined with a simulated quarter-car model. The input to the vehicle model was a set of randomly generated road profiles, each profile traversed at an appropriate speed. Modified skyhook damping tests showed a simultaneous improvement over the optimum passive case of 13 per cent in vertical body acceleration and 8 per cent in dynamic tyre forces. Full-scale vehicle tests of the damper on a heavy tri-axle trailer were carried out. Implementation of modified skyhook damping yielded a simultaneous improvement over the optimum passive case of 8 per cent in vertical body acceleration and 8 per cent in dynamic tyre forces. © IMechE 2008.

Effect of sailkite in improving trawl gear performance

Effectiveness of sailkite has been evaluated in two trawl designs, namely, a 25m high opening trawl and a 32m large mesh demersal trawl, rigged with sailkite through full scale comparative field trials. A 25m high opening trawl showed significant increase in total catch by 54.4% ribbon fish (Trichiurus spp.) alone by 138.3% with a reduction in miscellaneous catch, comprising mostly small sciaenids and juvenile fish, by 13.2% while 32m large mesh demersal trawl showed an improvement in total catch by 9%, ribbon fish by 17.2% and miscellaneous catch by 7.7%. The difference in fishing performance between the two gear arrangements has been attributed to changed net mouth configuration because of higher head line lift and also the possible herding effect on the fish in the vicinity of trawl mouth, due to addition of sailkite.

Mobilization distance for upheaval buckling of shallowly buried pipelines

Buried pipelines may be subject to upheaval buckling because of thermally induced compressive stresses. As the buckling load of a strut decreases with increasing out of straightness, not only the maximum available resistance from the soil cover, but also the movement of the pipeline required to mobilize this are important factors in design. This paper will describe the results of 15 full-scale laboratory tests that have been carried out on pipeline uplift in both sandy and rocky backfills. The cover to diameter ratio ranged from 0.1 to 6. The results show that mobilization distance exhibits a linear relationship with H=D ratio and that the postpeak uplift force-displacement response can be accurately modeled using existing models. A tentative design approach is suggested; the maximum available uplift resistance may be reliably predicted from the postpeak response, and the mobilization distance may be predicted using the relationships described in this paper. © 2012 American Society of Civil Engineers.

Investigating landing gear noise using fly-over data: The case of a Boeing 747-400

Modeling the noise originating from a landing gear has proven to be a challenging task, because of its complicated structure. In full-scale, landing gear noise can only be investigated experimentally by source localization techniques and fly-over measurements with microphone arrays. In the present work, measurements of a Boeing B747-400 were used to determine the contribution of the landing gear to the overall noise emitted during a fly-over and how the broadband noise from the landing gear scales with the flight velocity. A tonal source from the nose landing gear was identified at 380 Hz with a harmonic at 760 Hz and it most likely originates from a cavity. It was also found that the Power Spectral Density (PSD) of the high frequency broadband component varies linearly with frequency and there is some scaling with the ow velocity. Finally, the nose landing gear was shown to be a significant contributor to the overall airframe noise as expected.

Oxygen carrier dispersion in inert packed beds to improve performance in chemical looping combustion

Various packed beds of copper-based oxygen carriers (CuO on Al2O3) were tested over 100 cycles of low temperature (673K) Chemical Looping Combustion (CLC) with H2 as the fuel gas. The oxygen carriers were uniformly mixed with alumina (Al2O3) in order to investigate the level of separation necessary to prevent agglomeration. It was found that a mass ratio of 1:6 oxygen carrier to alumina gave the best performance in terms of stable, repeating hydrogen breakthrough curves over 100 cycles. In order to quantify the average separation achieved in the mixed packed beds, two sphere-packing models were developed. The hexagonal close-packing model assumed a uniform spherical packing structure, and based the separation calculations on a hypergeometric probability distribution. The more computationally intensive full-scale model used discrete element modelling to simulate random packing arrangements governed by gravity and contact dynamics. Both models predicted that average 'nearest neighbour' particle separation drops to near zero for oxygen carrier mass fractions of x≥0.25. For the packed bed systems studied, agglomeration was observed when the mass fraction of oxygen carrier was above this threshold. © 2013 Elsevier B.V.

Behaviour of cast-iron tunnel segmental joint from the 3D FE analyses and development of a new bolt-spring model

The behaviour of cast-iron tunnel segments used in London Underground tunnels was investigated using the 3-D finite element (FE) method. A numerical model of the structural details of cast-iron segmental joints such as bolts, panel and flanges was developed and its performance was validated against a set of full-scale tests. Using the verified model, the influence of structural features such as caulking groove and bolt pretension was examined for both rotational and shear loading conditions. Since such detailed modelling of bolts increases the computational time when a full scale segmental tunnel is analysed, it is proposed to replace the bolt model to a set of spring models. The parameters for the bolt-spring models, which consider the geometry and material properties of the bolt, are proposed. The performance of the combined bolt-spring and solid segmental models are evaluated against a more conventional shell-spring model. © 2014 Elsevier Ltd.

Experimental behaviour of barrel vaulted structure subjected to rocking of the abutments

In this paper, the transverse rocking mechanism of a barrel vaulted structure subjected to horizontal cyclic loads is analysed by means of experimental tests on full scale model and by means of non-linear FE analyses. The study is part of an ongoing experimental and theoretical research program, developed by the University of Brescia, concerning the seismic behaviour of ancient masonry buildings. The scope of the paper is to provide some evidence of the rocking mechanism experienced by barrel vaulted structures under horizontal loading. The understanding of the behaviour of these structural systems is necessary for their seismic vulnerability assessment, as well as for the correct design of possible strengthening techniques. A numeric FE model was validated through comparison with the experimental results and it was used to verify the efficiency of two common strengthening solutions: the technique of the overlaying reinforced concrete slab and the technique of the thin spandrel walls. Experimental and numeric results will be discussed in the paper.

Seismic behaviour of barrel vault systems

In this paper, the experimental study on the rocking behaviour of a full scale barrel vaulted structure undergo cyclic horizontal loading is discussed. The study is the first part of an ongoing experimental and theoretical research program, developed by the University of Brescia, concerning the seismic behaviour of masonry buildings. The scope of the paper is to provide some evidence of the rocking mechanism experienced by barrel vaulted structures undergo horizontal loading. Understanding of the behaviour of such structural systems is fundamental for their seismic vulnerability assessment, as well as for the correct design of possible strengthening techniques. The structural behaviour is also investigated by means of non linear finite element analyses. Numerical results are validated through comparison with experimental results. After validation, the FE model can be applied to different case studies.

基于多层抽样反馈的传感器网络时间同步算法

针对目前传感器网络时间同步算法存在的问题,提出了一种全网时间同步算法FTS(full-scale time synchronization),其基本思想是从整体角度对传感器网络实施逐轮次的推送式的时间同步操作,并通过少量抽样节点的反馈数据计算时间同步操作的有关参数。在常见的TelosB节点上给出了FTS算法的实现。实验和分析表明,FTS算法是一类收敛快速、资源高效、同步精度较高和运算复杂度较低的时间同步方法,目前已经在无线传感器网络测试平台上得到了应用。

Human plasma proteome analysis by multidimensional chromatography prefractionation and linear ion trap mass spectrometry identification

A resurgence of interest in the human plasma proteome has occurred in recent years because it holds great promise of revolution in disease diagnosis and therapeutic monitoring. As one of the most powerful separation techniques, multidimensional liquid chromatography has attracted extensive attention, but most published works have focused on the fractionation of tryptic peptides. In this study, proteins from human plasma were prefractionated by online sequential strong cation exchange chromatography and reversed-phase chromatography. The resulting 30 samples were individually digested by trypsin, and analyzed by capillary reversed-phase liquid chromatography coupled with linear ion trap mass spectrometry. After meeting stringent criteria, a total of 1292 distinct proteins were successfully identified in our work, among which, some proteins known to be present in serum in < 10 ng/mL were detected. Compared with other works in published literatures, this analysis offered a more full-scale list of the plasma proteome. Considering our strategy allows high throughput of protein identification in serum, the prefractionation of proteins before MS analysis is a simple and effective method to facilitate human plasma proteome research.

Mixed methods feasibility study for a trial of blood pressure telemonitoring for people who have had stroke/transient ischaemic attack (TIA).

Background Good blood pressure (BP) control reduces the risk of recurrence of stroke/transient ischaemic attack (TIA). Although there is strong evidence that BP telemonitoring helps achieve good control, none of the major trials have considered the effectiveness in stroke/TIA survivors. We therefore conducted a feasibility study for a trial of BP telemonitoring for stroke/ TIA survivors with uncontrolled BP in primary care. Method Phase 1 was a pilot trial involving 55 patients stratified by stroke/TIA randomised 3:1 to BP telemonitoring for 6 months or usual care. Phase 2 was a qualitative evaluation and comprised semi-structured interviews with 16 trial participants who received telemonitoring and 3 focus groups with 23 members of stroke support groups and 7 carers. Results Overall, 125 patients (60 stroke patients, 65 TIA patients) were approached and 55 (44%) patients were randomised including 27 stroke patients and 28 TIA patients. Fifty-two participants (95%) attended the 6-month follow-up appointment, but one declined the second daytime ambulatory blood pressure monitoring (ABPM) measurement resulting in a 93% completion rate for ABPM − the proposed primary outcome measure for a full trial. Adherence to telemonitoring was good; of the 40 participants who were telemonitoring, 38 continued to provide readings throughout the 6 months. There was a mean reduction of 10.1 mmHg in systolic ABPM in the telemonitoring group compared with 3.8 mmHg in the control group, which suggested the potential for a substantial effect from telemonitoring. Our qualitative analysis found that many stroke patients were concerned about their BP and telemonitoring increased their engagement, was easy, convenient and reassuring Conclusions A full-scale trial is feasible, likely to recruit well and have good rates of compliance and follow-up.