Construction Rehabilitation in Civil Engineering at bachelor degree level: A guideline course

ABSTRACT: In general terms, construction rehabilitation is not sufficiently studied worldwide in civil engineering schools. This article proposes an international guideline course on construction rehabilitation for civil engineering students at the bachelor degree level. As we live in an increasingly globalized world, the course aims to prepare students in the same basic concepts so the course content and its focus can be common for all civil engineering programs worldwide. Nevertheless, the course should be considered as a general guideline. At each university, special attention should be paid to the topics that are most common due to the varying construction practices, preservation laws and regulations, and legal jurisdiction governing the scope of practice in construction rehabilitation that exist in the region/country in which the university is located. Moreover, the guideline course should be focused on existing building types, both significant historic ones and those that make up the day-to-day rehabilitation market. To achieve this, the initial step of the methodology was the study and integration of the results obtained in a survey sent to lecturers at 89 universities in 30 countries around the world. Then, a preliminary grouping was done of topics that could be included in the course, preassigning a teaching time to each topic. Later, various renowned experts in the matter audited the tentative guideline course. Finally, based on their opinions and comments, the definitive guideline course was rewritten. Through this course, civil engineering students will improve their ability to recognize, analyze, diagnose, and solve problems that commonly appear in existing buildings, and they will increase their knowledge about maintaining and conserving them

Second-order fatigue of intrinsic mean stress under random loadings

A fatigue process due to random loading that is progressively damaging a certain structural detail will vary in the presence of mean stresses. The variations are already considered in crack propagation laws and by applying equivalent 0-mean stress ranges from the Palmgren–Miner linear rule. Nevertheless, if the mean stress is intrinsic, instead of a direct consequence of the random loading, other second-order effects will have to be taken into account. Those effects are cycle quasi-ordering, histogram variations, and apparent mean tension, which are identified and defined in this study and, finally, developed in a case study for demonstrative purposes

Calcium Looping with Enhanced Sorbent Performance: Experimental Testing in A Large Pilot Plant

AbstractPostcombustion CO2 capture by Calcium Looping (CaL) has been successfully carried out for more than 700 hours in a 1.7 MWth continuous pilot facility in La Pereda (Spain). The pilot is equipped with two interconnected circulating fluidized bed reactors: a CO2 carbonator, where CaCO3 is formed when CO2 is captured from a combustion flue gas in contact with fine particles of CaO, and an oxy-fired calciner, where a highly concentrated stream of CO2 is generated by decomposing the CaCO3 formed in the carbonator. CaL is a technology that has the potential to achieve a substantial reduction in the cost of CO2 capture because of the capability to recover waste heat and generate more power from the additional fuel fired in the calciner. However, one of the weaknesses of CaL systems is the rapid deactivation of the sorbent. The EU “ReCaL” project (http://recal-project.eu/) aims to develop a robust and simple reactivation process to stabilize sorbent activity in CaL systems, based on the thermodynamic and kinetic ability of the sorbent to increase its CaCO3 conversion under enhanced carbonation conditions. This paper presents a first attempt to demonstrate the concept at the scale of the La Pereda 1.7 MWth pilot plant. It describes the redesign and retrofitting exercise conducted in the pilot and discusses the initial experimental results achieved when one of the loop seals is used as “recarbonator” reactor (putting a small flow of pure CO2 in contact with partially carbonated particles arriving from the carbonator). The findings of this study suggest that recarbonation could be responsible for about 100% increase in the average CO2 carrying capacity of the material used in the CO2 capture step taking place in the carbonator. This could allow CaL systems to operate with very low limestone make-up flow requirements, making this emerging capture technology more competitive

Testing postcombustion CO2 capture with CaO in a 1.7 MWt pilot facility

AbstractCalcium looping, CaL, is a new and rapidly developing technology that makes use of CaO as a high temperature regenerable sorbent of CO2. Previous theoretical and lab scale studies have shown that this technology could lead to a substantial reduction in the cost of CO2 capture and energy penalties because heat can be effectively recovered from this high temperature solid looping system. We report in this paper on the first results from a pilot plant designed to demonstrate the viability of postcombustion capture of CO2 using CaL under conditions comparable to those expected in a large scale plant. The pilot includes two interconnected circulating fluidized bed reactors of 15 m height: a CO2 absorber (carbonator) able to treat up to 2400kg/h (equivalent to about 1.7 MWth), and an oxy-fired CFB calciner with a firing power between 1-3 MWth. CO2 capture efficiencies over 90% have been experimentally observed, including continuous operation with highly cycled solids in the system (i.e. with modest CO2 carrying capacities). SO2 capture is shown to be extremely high, with concentrations of SO2 well below 10 ppmv at the exit of the carbonator. Closure of carbon and sulfur balances is satisfactory. These results should be valuable base for model validation and scaling up purposes in future stages of the EU FP7 “CaOling” project, under which this investigation has been carried out

Infective Endocarditis in Diabetic Patients: A Different Profile with Prognostic Consequences

Background. Infective Endocarditis (IE) is a severe condition. Diabetes mellitus (DM) has been associated with a poor prognosis in other settings. Our aim was to describe the profile and prognosis of IE with and without DM and to analyze the prognostic relevance of DM-related organ damage. Methods. Retrospective analysis of the Spanish IE Registry (2008–2020). Results. The cohort comprises 5590 IE patients with a mean age of 65.0 ± 15.5 years; 3764 (67.3%) were male. DM was found in 1625 patients (29.1%) and 515 presented DM-related organ damage. DM prevalence during the first half of the study period was 27.6% vs. 30.6% in the last half, p = 0.015. Patients with DM presented higher in-hospital mortality than those without DM (521 [32.1%] vs. 924 [23.3%], p < 0.001) and higher one-year mortality (640 [39.4%] vs. 1131 [28.5%], p < 0.001). Among DM patients, organ damage was associated with higher in-hospital (200 [38.8%] vs. 321 [28.9%], p < 0.001) and one-year mortality (247 [48.0%] vs. 393 [35.4%], p < 0.001). Multivariate analyses showed an independent association of DM with in-hospital (odds ratio [OR] = 1.34, 95% confidence interval [CI]: 1.16–1.55, p < 0.001) and one-year mortality (OR = 1.38, 95% CI: 1.21–1.59, p < 0.001). Among DM patients, organ damage was independently associated with higher in-hospital (OR = 1.37, 95% CI: 1.06–1.76, p = 0.015) and one-year mortality (OR = 1.59, 95% CI = 1.26–2.01, p < 0.001) Conclusions. The prevalence of DM among patients with IE is increasing and is already above 30%. DM is independently associated with a poor prognosis, particularly in the case of DM with organ damage

Process simulation and economic feasibility assessment of the methanol production via tri-reforming using experimental kinetic equations

The purpose of this paper is to assess via techno-economic metrics the feasibility of a tri-reforming coupled methanol process. The simulation of the tri-reforming reactor considered empiric kinetic equations, developed by our group in previous studies. The flue gas coming from the furnace that provides the energy required by the reforming reactor was also used as feed, in order to reduce the CO2 emissions. A sensitivity analysis was carried out to determine the influence of the feed composition and temperature in the tri-reforming process results, studying H2O/CH4 and O2/CH4 ratios (0.5–1.5 and 0.35–0.40, respectively), and varying the temperature between 850 and 1050 °C. The methanol plant was also simulated, and an economical study was carried out to know if the proposed process would be economically feasible. The most relevant economic parameters (including the Net Present Value, the Internal Rate of Return, the Payback Period and the break-even) were calculated, showing a quite robust process from an economical point of view.El propósito de este documento es evaluar a través de métricas tecnoeconómicas la viabilidad de un proceso de metanol acoplado de triple reforma. La simulación del reactor de tri-reformado consideró ecuaciones cinéticas empíricas, desarrolladas por nuestro grupo en estudios previos. También se utilizó como alimentación el gas de combustión procedente del horno que proporciona la energía requerida por el reactor de reformado, con el fin de reducir las emisiones de CO 2 . Se realizó un análisis de sensibilidad para determinar la influencia de la composición y temperatura de la alimentación en los resultados del proceso de tri-reformado, estudiando H 2 O/CH 4 y O 2 /CH 4proporciones (0.5-1.5 y 0.35-0.40, respectivamente), y variando la temperatura entre 850 y 1050 °C. También se simuló la planta de metanol y se realizó un estudio económico para saber si el proceso propuesto sería económicamente factible. Se calcularon los parámetros económicos más relevantes (incluyendo el Valor Presente Neto, la Tasa Interna de Retorno, el Periodo de Recuperación y el punto de equilibrio), mostrando un proceso bastante robusto desde el punto de vista económico

Relationship between microstructure and fracture types in a UNS S32205 duplex stainless steel

Duplex stainless steels are susceptible to the formation of sigma phase at high temperature which could potentially be responsible for catastrophic service failure of components. Thermal treatments were applied to duplex stainless steels in order to promote the precipitation of different fractions of sigma phase into a ferrite-austenite microstructure. Quantitative image analysis was employed to characterize the microstructure and Charpy impact tests were used in order to evaluate the mechanical degradation caused by sigma phase presence. The fracture morphology of the Charpy test specimens were thoroughly observed in SEM, looking for a correlation between the microstructure and the fracture types in UNS S32205 duplex stainless steel. The main conclusion is the strong embrittlement effect of sigma phase since it is possible to observe a transition from transgranular fracture to intergranular fracture as increases the percentage of sigma phase. Thus, the mixed modes of fracture are predominant in the present study with high dependence on sigma phase percentages obtained by different thermal treatments

Diversity and Functional Traits of Lichens in Ultramafic Areas: A Literature Based Worldwide Analysis Integrated by Field Data at the Regional Scale

While higher plant communities found on ultramafics are known to display peculiar characteristics, the distinguishability of any peculiarity in lichen communities is still a matter of contention. Other biotic or abiotic factors, rather than substrate chemistry, may contribute to differences in species composition reported for lichens on adjacent ultramafic and non-ultramafic areas. This work examines the lichen biota of ultramafics, at global and regional scales, with reference to species-specific functional traits. An updated world list of lichens on ultramafic substrates was analyzed to verify potential relationships between diversity and functional traits of lichens in different Köppen–Geiger climate zones. Moreover, a survey of diversity and functional traits in saxicolous communities on ultramafic and non-ultramafic substrates was conducted in Valle d’Aosta (North-West Italy) to verify whether a relationship can be detected between substrate and functional traits that cannot be explained by other environmental factors related to altitude. Analyses (unweighted pair group mean average clustering, canonical correspondence analysis, similarity-difference-replacement simplex approach) of global lichen diversity on ultramafic substrates (2314 reports of 881 taxa from 43 areas) displayed a zonal species distribution in different climate zones rather than an azonal distribution driven by the shared substrate. Accordingly, variations in the frequency of functional attributes reflected reported adaptations to the climate conditions of the different geographic areas. At the regional scale, higher similarity and lower species replacement were detected at each altitude, independent from the substrate, suggesting that altitude-related climate factors prevail over putative substrate–factors in driving community assemblages. In conclusion, data do not reveal peculiarities in lichen diversity or the frequency of functional traits in ultramafic areas

Indefinites in comparatives

The goal of this paper is to explain the meaning and distribution of indefinites in comparatives, focusing on English some and any and German irgend-indefinites. We consider three competing theories of comparatives in combination with an alternative semantics of some and any, and a novel account of stressed irgend-indefinites. One of the resulting accounts, based on Heim’s analysis of comparatives, predicts all the relevant differences in quantificational force, and explains why free choice indefinites are licensed in comparatives