A variational approach to strongly damped wave equations

We discuss a Hilbert space method that allows to prove analytical well-posedness of a class of linear strongly damped wave equations. The main technical tool is a perturbation lemma for sesquilinear forms, which seems to be new. In most common linear cases we can furthermore apply a recent result due to Crouzeix--Haase, thus extending several known results and obtaining optimal analyticity angle.Comment: This is an extended version of an article appeared in \emph{Functional Analysis and Evolution Equations -- The G\"unter Lumer Volume}, edited by H. Amann et al., Birkh\"auser, Basel, 2008. In the latest submission to arXiv only some typos have been fixe

Well-posedness for degenerate third order equations with delay and applications to inverse problems

[EN] In this paper, we study well-posedness for the following third-order in time equation with delay <disp-formula idoperators defined on a Banach space X with domains D(A) and D(B) such that t)is the state function taking values in X and u(t): (-, 0] X defined as u(t)() = u(t+) for < 0 belongs to an appropriate phase space where F and G are bounded linear operators. Using operator-valued Fourier multiplier techniques we provide optimal conditions for well-posedness of equation (0.1) in periodic Lebesgue-Bochner spaces Lp(T,X), periodic Besov spaces Bp,qs(T,X) and periodic Triebel-Lizorkin spaces Fp,qs(T,X). A novel application to an inverse problem is given.The first, second and third authors have been supported by MEC, grant MTM2016-75963-P. The second author has been supported by AICO/2016/30. The fourth author has been supported by MEC, grant MTM2015-65825-P.Conejero, JA.; Lizama, C.; Murillo-Arcila, M.; Seoane Sepúlveda, JB. (2019). 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Housing Hearing #1, Extract from WEAN Tape - January 30, 1959

https://digitalcommons.ric.edu/irving_fain/1049/thumbnail.jp

Urinary dysfunction in women following total mesorectal excision versus partial mesorectal excision for treatment of rectal cancer

Abstract Background Colorectal cancer is a condition which is associated with substantial morbidity and mortality. The aim of this study was to assess urinary dysfunction and its effect on quality of life in women who underwent total mesorectal excision compared to women treated by partial mesorectal excision for treatment of rectal cancer. Methods We performed a retrospective cohort study at a tertiary university hospital between January 2014 and December 2019. A comparison was performed between women who underwent total mesorectal excision as opposed to partial mesorectal excision for treatment of rectal cancer. Pre-operative, intra-operative and post-operative data were compared between groups. Data regarding radiation therapy was recorded and compared as well. Urinary dysfunction and its impact on quality of life were assessed using UDI-6 and USIQ questionnaires. Further univariate and multivariate analyses were performed in the attempt of assessing risk factors for urinary dysfunction. Results A total of 107 women were included in the study, 73 women underwent partial mesorectal excision as opposed to 34 women who were treated by total mesorectal excision. Twenty-five women in the TME group underwent radiation therapy prior to surgery as opposed to none in the PME group (p < 0.001). Urinary dysfunction following surgery as assessed using the UDI-6 questionnaire did not differ between groups. Similar findings were recorded with regard to the impact of urinary dysfunction on quality of life as assessed using the USIQ questionnaire. Following multivariate analysis longer hospital stay was associated with increased risk of some degree of urinary dysfunction. Conclusions Women undergoing total mesorectal excision have comparable results to partial mesorectal excision with regard to urinary dysfunction

Effects of interpass temperature on the metallurgical changes and mechanical properties of dissimilar steel joints of ASTM A182-F22 welded with nickel alloys

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoAs ligas de nÃquel podem ser utilizadas na uniÃo de juntas dissimilares de aÃos carbono baixa liga. Uma das finalidades desta uniÃo à evitar a formaÃÃo de trincas induzidas pelo hidrogÃnio. Existe uma limitaÃÃo por norma que impÃe a temperatura de interpasse mÃxima de 150ÂC para soldagem com ligas de nÃquel. Contudo, a temperatura de interpasse baixa reduz a produtividade e consequentemente aumenta os custos de fabricaÃÃo. Um estudo que avalia como a temperatura de preaquecimento/interpasse na soldagem dissimilar influencia as alteraÃÃes metalÃrgicas e propriedades mecÃnicas à oportuno. Desta forma, o objetivo geral deste trabalho à avaliar o efeito do aumento da temperatura de interpasse nas alteraÃÃes metalÃrgicas e nas propriedades mecÃnicas de juntas dissimilares soldadas do aÃo ASTM A182-F22 com diferentes ligas de nÃquel. Foram realizadas soldagens MIG/MAG automÃtica em juntas do aÃo (ASTM A182-F22) utilizando diferentes ligas de nÃquel como metal de adiÃÃo e diferentes temperaturas de interpasse (35ÂC, 150ÂC e 350ÂC). A energia de soldagem foi mantida constante (1,0 kJ/mm). Baseado nos resultados obtidos o aumento da temperatura de preaquecimento tende a reduzir a fraÃÃo de precipitados, decorrente do aumento da diluiÃÃo. O coeficiente de distribuiÃÃo do Mo e Nb diminuem com o aumento do teor de ferro na solda. Isto, por sua vez, torna mais forte a segregaÃÃo destes elementos. A temperatura de interpasse tendeu a reduzir a dureza da (ZTA-GG), por conta da reduÃÃo da velocidade de resfriamento. Nos ensaios de traÃÃo os corpos de prova romperam na regiÃo referente ao metal de base. Houve uma reduÃÃo no limite de escoamento nas condiÃÃes soldadas com temperatura de 350ÂC, sendo uma possÃvel causa a precipitaÃÃo de carbonetos devido ao preaquecimento e aos multipasses. Os ensaios de Charpy-V indicaram que, de uma forma geral, o aumento da temperatura de interpasse reduziu a tenacidade na zona fundida. A energia absorvida na interface sofreu reduÃÃo com o aumento da temperatura de interpasse, decorrente do aumento da descarbonetaÃÃo. O tempo de soldagem foi reduzido de forma considerÃvel com o aumento de temperatura de interpasse, entretanto, deve-se avaliar as alteraÃÃes na ZTA e ZF.Nickel alloys can be used to weld dissimilar joints of low alloy carbon steels. One of the purposes of this union is to avoid the formation of hydrogen induced cracking. According codes and standard there is a limitation that imposes the maximum interpass temperature at 150ÂC for welding using nickel alloys. However, the low interpass temperature reduces productivity and increases manufacturing costs. A study that evaluates effect of the preheating and interpass temperature of dissimilar welds on the metallurgical changes and mechanical properties is of great relevance. In this way, the general objective of this study is to assess the effect of interpass temperature on metallurgical changes and mechanical properties of dissimilar welded joints among ASTM A182-F22 steel and different nickel-based alloys. GMAW were carried out on joints of steel (ASTM A182-F22) using different nickel-based alloys as filler metal and different interpass temperatures (35ÂC, 150ÂC and 350ÂC). The heat input was kept constant (1.0 kJ/mm). Based on the results obtained it was observed that increasing preheating temperature there is a tends to reduce the precipitates content, because of dilution. The distribution coefficient of Mo and Nb decrease with the increase of iron content in the fusion zone, making stronger the segregation of these elements. Interpass temperature tend to reduce the HAZ hardness, due to the in cooling rate reduction caused by increase interpass temperature. In the tensile tests failure in the base metal. There was a reduction in yield strength for welds produced with 350ÂC preheat temperature, being a possible cause the precipitation of carbides due to preheating and multipasses. The Charpy-V tests indicated that, generally, the increase in interpass temperature reduced the toughness in the fusion zone. The absorbed energy by the interface dropped when interpass temperature increase. The welding time was considerably reduced with the interpass temperature increase, however, it should be to considerate changes in HAZ and fusion zone