Sensitivity analysis of the hygrothermal behaviour of homogeneous masonry constructions: Interior insulation, rainwater infiltration and hydrophobic treatment

2021 ◽  
Vol 44 (6) ◽  
pp. 510-538
Author(s):  
Klaas Calle ◽  
Nathan Van Den Bossche
Keyword(s):  
Infiltration Rate ◽  
Frost Damage ◽  
Water Infiltration ◽  
Sensitivity Analyses ◽  
Mould Growth ◽  
Damage Potential ◽  
Interior Surface ◽  
High Dependency ◽  
The Impact ◽  
Damage Criteria

Historical masonry constructions are difficult to mimic in hygrothermal models. The material properties of the walls are often highly uncertain due to the natural origin of the aggregates and the various, manual production processes used through time. Therefore, sensitivity analyses based on probabilistic simulations are powerful tools to indicate the risks on damage in masonry constructions. Damage criteria for relevant pathologies such as frost damage, potential decay of wooden beam heads and mould growth at the interior surface are used. The assessment methods (Scatter plots, Classification trees and Sobol indices) are based on 1D Heat, Air and Moisture simulations, including realistic variations on climate parameters and wall properties. These methodologies are applied to probabilistic simulations in which a potential damage risk is expected in historic masonries. The application of interior insulation, the use of hydrophobic treatments, and the impact of potential water infiltrations through cracks are discussed. In most of these situations a high dependency of each of the damage criteria on the rain intensity, the trend of the moisture retention/liquid conductivity curve and the absorption coefficient is evident, but also additional insights are found. For example, the thermal impact of interior insulation is negligible compared to its reduction of the first phase drying potential towards the interior. For hydrophobic treatments, the risk for damage typically decreases, but in combination with a rain water infiltration rate above approximately 5% of the wind driven rain the risk on mould growth at the interior surface significantly increases.

Implementation of rainwater infiltration measurements in hygrothermal modelling of non-insulated brick cavity walls

2019 ◽  
Vol 43 (6) ◽  
pp. 477-502 ◽  
Author(s):  
Klaas Calle ◽  
Charlotte Coupillie ◽  
Arnold Janssens ◽  
Nathan Van Den Bossche
Keyword(s):  
Infiltration Rate ◽  
Performance Criterion ◽  
Water Infiltration ◽  
Cavity Wall ◽  
Wall Surface ◽  
Rainwater Infiltration ◽  
Interior Wall ◽  
In Situ Investigation ◽  
Damage Criteria

The watertightness of solid masonry walls is generally based on the concept of buffering and afterwards drying out the absorbed rainwater. In cavity walls, on the contrary, the air layer provides a capillary break between the inner and outer leafs allowing drainage of rainwater and preventing infiltration to the interior wall surface. For assessing moisture-related risks, heat, air and moisture models have proven to be a valuable tool, but in the case of cavity walls two problems arise: the degree of water infiltration into the cavity is unknown, and no consensus is available on the method that should be used to implement these infiltrations in a simulation. For example, for the existing buildings, it is worthwhile to investigate whether injecting cavity wall insulation induces an increase or decrease in moisture-related pathologies, in contrast to adopting a fixed performance criterion for assessment. However, to complete a thorough analysis of a brick cavity wall, it is first useful to review the hygrothermal behaviour of cavity walls as it has been previously described in the literature. As such, this article provides a summary of experimental water infiltration results for cavity walls as described in the literature, discusses experimental results of four test walls subjected to four test protocols and extracts from these results the water infiltration rate for implementation in heat, air and moisture models. Finally, several methods for implementing the infiltrations in heat, air and moisture simulations are presented and evaluated based on different damage criteria. In general, the new modelling approaches are considered to provide realistic results. Nonetheless, an in situ investigation on whether mortar bridges occur in the cavity due to poor workmanship remains crucial to understanding the hygrothermal response as mortar bridges are found to have a dominant impact on the risk of mould growth at the interior wall surface.

scholarly journals Sensitivity of the hygrothermal behaviour of homogeneous masonry constructions: from Sobol indices to decision trees

2020 ◽  
Vol 172 ◽  
pp. 07001
Author(s):  
Klaas Calle ◽  
Nathan Van Den Bossche
Keyword(s):  
Frost Damage ◽  
Order Effects ◽  
Indoor Climate ◽  
Sobol Indices ◽  
Historic Masonry ◽  
High Dependency ◽  
Sensitivity Indices ◽  
Input Parameters ◽  
Detailed Assessment ◽  
Damage Criteria

Historic masonry constructions are difficult to mimic in hygrothermal models. Next to the usual uncertainties on the input of hygrothermal models as the outdoor/indoor climate also the properties of the wall themselves are often highly uncertain due to the natural origin of the aggregates and the various, manual production processes used through time. Therefore, this paper presents a probabilistic analysis that indicates the sensitivity of several damage criteria which are often encountered in practice such as mould growth at the interior surface, frost damage, and potential decay of wooden beam heads. The analysis is based on 1D simulations, including realistic variations on climate parameters as wall properties. With Kriging based surrogate modelling the output of the probabilistic simulations is translated into sensitivity indices, Total Sobol indices. These indices summarize the dependency of the damage criteria for each of the input parameters including multi order effects. The Total Sobol indices indicate a generally high dependency of each of the damage criteria on the rain intensity, the trend of the moisture retention/liquid conductivity curve and the absorption coefficient. Based on the probabilistic output binary flowcharts are generated to indicate for which combinations of input parameters high risks are to be expected. These binary flowcharts can be adopted by e.g. engineering firms to define whether, a more detailed assessment is required, and which input are necessary. This indicates when basic in situ assessments of the hygrothermal properties of the facade can suffice.

scholarly journals Hydrological Properties of a Clay Loam Soil as Affected by Biochar Application in a Pot Experiment

Agronomy ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 489
Author(s):  
Angela Libutti ◽  
Matteo Francavilla ◽  
Massimo Monteleone
Keyword(s):  
Bulk Density ◽  
Water Retention ◽  
Infiltration Rate ◽  
Water Infiltration ◽  
Pot Experiment ◽  
Water Retention Curve ◽  
Clay Loam ◽  
Clay Loam Soil ◽  
Loam Soil ◽  
The Impact

Improving soil-water relations by amending soil with biochar might play a significant role in increasing water availability for agricultural crops as well as decreasing water loss through drainage or runoff. While the effects of biochar on the hydrological properties on coarse-textured soils are generally positive and well-documented in the literature, studies on biochar effects on fine-textured soils are rather scarce and even contradictory. Therefore, the aim of this paper was to investigate the impact of biochar on the bulk density, water retention curve (together with several water capacitive indicators) and water infiltration rate in a clay loam soil. A pot experiment was carried out under lab conditions in which biochar was mixed with soil at rates of 0 (B0 or control), 2, 4, 6, 8 and 10% dw (B2, B4, B6, B8 and B10, respectively). Water retention of soil–biochar mixtures at different matrix potentials was determined using a pressure plate apparatus. From these measurements, a series of capacitive indicators was derived and the fitting of the van Genuchten model was also performed. Water infiltration into soil–biochar mixtures was measured by means of a mini-disk infiltrometer and the obtained data were analyzed both directly and by fitting the Philip’s model. Biochar significantly affected the considered soil properties. As the biochar rate increased, the bulk density decreased and water retention increased (B6, B8 and B10 > B2, B4 and B0), while the infiltration rate decreased (B0 > B2, B4, B6, B8 and B10). Although the experiment was performed on sieved and repacked soil samples under lab conditions, the results confirmed that biochar has the potential to increase plant-available water, while possibly reducing drainage water in a clay loam soil by lowering the infiltration rate.

scholarly journals Functional attributes: Compacting vs decompacting earthworms and influence on soil structure

2012 ◽  
Vol 58 (4) ◽  
pp. 556-565 ◽  
Author(s):  
Arnauth Martinez Guéi ◽  
Yannick Baidai ◽  
Jérôme Ebagnerin Tondoh ◽  
Jeroen Huising
Keyword(s):  
Soil Structure ◽  
Deciduous Forest ◽  
Positive Impact ◽  
Infiltration Rate ◽  
Water Infiltration ◽  
Earthworm Species ◽  
Insurance Hypothesis ◽  
Hyperiodrilus Africanus ◽  
Structure Regulation ◽  
The Impact

Abstract A short term field mesocosm experiment was performed in semi-deciduous forest areas of Ivory Coast to assess the impact of a decompacting (Hyperiodrilus africanus, Eudrilidae) and two compacting (Millsonia omodeoi and Dichogaster terraenigrae, Acanthodrilidae) earthworm species on soil properties. These species have been selected for their predominance in the region and their contrasting impact on soil structure. The experimental design consisted of a treatment without worms (control), and treatments with one, two or three species of earthworms. Both compacting and decompacting earthworms increased water infiltration rate in all treatments, with marked impact in H. africanus and M. omodeoi+D. terraenigrae treatments. Interactions between compacting and decompacting species resulted in more large aggregates in comparison to when the compacting species D. terraenigrae was alone. This may be accounted for by their compacting attribute as compacting earthworms are responsible for producing the highest number of large aggregates. The low values of mean weight diameter in treatments combining decompacting and compacting earthworms compared with compacting “M. omodeoi” one also confirmed the trend of decline in soil compaction in the presence of the decompacting species. These results showed positive impact of species richness on soil structure regulation, which is crucial in ecosystem productivity and support consequently the insurance hypothesis. In fact, this study showed that the preservation of earthworm species belonging to these two contrasting functional groups is essential for the maintenance of stable soil structure regulation in agro-tropical ecosystems.

Comparative study of the impact of two mechanical perforation densities on the behavior of a sandy soil

2012 ◽  
Vol 8 (1) ◽  
pp. 37-48
Author(s):  
S. Chehaibi ◽  
K. Abrougui ◽  
F. Haouala
Keyword(s):  
Soil Water ◽  
Sandy Soil ◽  
Water Infiltration ◽  
Cone Penetration ◽  
Initial State ◽  
Soil Water Infiltration ◽  
Good Improvement ◽  
The Impact ◽  
Positive Effect ◽  
Resistance To Penetration

The effects of mechanical perforation densities by extracting soil cores through an aerator Vertidrain with a working width of 1.6 m and equipped with hollow tines spaced of 65 mm, were studied on a sandy soil of a grassy sward in the Golf Course El Kantaoui in Sousse (Tunisia). The mechanical aeration was performed at two densities: 250 and 350 holes/m2. The cone penetration resistance and soil water infiltration were measured. These parameters were performed at initial state before aeration (E0) and then on the 10th, 20th and 30th day after aeration. These results showed that perforation density of 350 holes/m2 had a positive effect on the soil by reducing its cone resistance to penetration compared to the initial state (Rp = 14.8 daN/cm2). At 5 cm depth the decrease in resistance to penetration was 34% and 43% on the 10th and 20th day after aeration, respectively. However, on the 30th day after aeration the soil resistance to penetration tended to grow and its value compared to the initial state decreased only by 21 and 26%, respectively, at 5 and 15 cm of depth only by 10% and 9% with 250 holes/m2 density. The soil water infiltration made a good improvement after aeration compared to the initial state. This parameter increased from 4.8 cm/h to 8.3, 10.9 and 13.1 cm/h with 250 holes/m2 density and to 10, 12.9 and 14.8 cm/h with 350 holes/m2 density on the 10th, 20th and 30th day following the aeration.

Body mass index and risk of all-cause mortality in normotensive and hypertensive adults: The Rural Chinese Cohort Study

2021 ◽  
pp. 1-25
Author(s):  
Qionggui Zhou ◽  
Xuejiao Liu ◽  
Yang Zhao ◽  
Pei Qin ◽  
Yongcheng Ren ◽  
...  
Keyword(s):  
Cohort Study ◽  
Population Based ◽  
Normal Weight ◽  
Sensitivity Analyses ◽  
Hypertension Status ◽  
Moderation Effect ◽  
Increased Risk ◽  
All Cause Mortality ◽  
Chinese Cohort ◽  
The Impact

Abstract Objective: The impact of baseline hypertension status on the BMI–mortality association is still unclear. We aimed to examine the moderation effect of hypertension on the BMI–mortality association using a rural Chinese cohort. Design: In this cohort study, we investigated the incident of mortality according to different BMI categories by hypertension status. Setting: Longitudinal population-based cohort Participants: 17,262 adults ≥18 years were recruited from July to August of 2013 and July to August of 2014 from a rural area in China. Results: During a median 6-year follow-up, we recorded 1109 deaths (610 with and 499 without hypertension). In adjusted models, as compared with BMI 22-24 kg/m2, with BMI ≤18, 18-20, 20-22, 24-26, 26-28, 28-30 and >30 kg/m2, the HRs (95% CI) for mortality in normotensive participants were 1.92 (1.23-3.00), 1.44 (1.01-2.05), 1.14 (0.82-1.58), 0.96 (0.70-1.31), 0.96 (0.65-1.43), 1.32 (0.81-2.14), and 1.32 (0.74-2.35) respectively, and in hypertensive participants were 1.85 (1.08-3.17), 1.67 (1.17-2.39), 1.29 (0.95-1.75), 1.20 (0.91-1.58), 1.10 (0.83-1.46), 1.10 (0.80-1.52), and 0.61 (0.40-0.94) respectively. The risk of mortality was lower in individuals with hypertension with overweight or obesity versus normal weight, especially in older hypertensives (≥60 years old). Sensitivity analyses gave consistent results for both normotensive and hypertensive participants. Conclusions: Low BMI was significantly associated with increased risk of all-cause mortality regardless of hypertension status in rural Chinese adults, but high BMI decreased the mortality risk among individuals with hypertension, especially in older hypertensives.

scholarly journals Impact of public health interventions to curb SARS-CoV-2 spread assessed by an evidence-educated Delphi panel and tailored SEIR model

2021 ◽  
Author(s):  
Bernd Brüggenjürgen ◽  
Hans-Peter Stricker ◽  
Lilian Krist ◽  
Miriam Ortiz ◽  
Thomas Reinhold ◽  
...  
Keyword(s):  
Public Health ◽  
Transmission Rate ◽  
Latency Period ◽  
Policy Decision ◽  
Sensitivity Analyses ◽  
Delphi Panel ◽  
Time Step ◽  
Seir Model ◽  
Health Policy Decision ◽  
The Impact

Abstract Aim To use a Delphi-panel-based assessment of the effectiveness of different non-pharmaceutical interventions (NPI) in order to retrospectively approximate and to prospectively predict the SARS-CoV-2 pandemic progression via a SEIR model (susceptible, exposed, infectious, removed). Methods We applied an evidence-educated Delphi-panel approach to elicit the impact of NPIs on the SARS-CoV-2 transmission rate R0 in Germany. Effectiveness was defined as the product of efficacy and compliance. A discrete, deterministic SEIR model with time step of 1 day, a latency period of 1.8 days, duration of infectiousness of 5 days, and a share of the total population of 15% assumed to be protected by immunity was developed in order to estimate the impact of selected NPI measures on the course of the pandemic. The model was populated with the Delphi-panel results and varied in sensitivity analyses. Results Efficacy and compliance estimates for the three most effective NPIs were as follows: test and isolate 49% (efficacy)/78% (compliance), keeping distance 42%/74%, personal protection masks (cloth masks or other face masks) 33%/79%. Applying all NPI effectiveness estimates to the SEIR model resulted in a valid replication of reported occurrence of the German SARS-CoV-2 pandemic. A combination of four NPIs at consented compliance rates might curb the CoViD-19 pandemic. Conclusion Employing an evidence-educated Delphi-panel approach can support SARS-CoV-2 modelling. Future curbing scenarios require a combination of NPIs. A Delphi-panel-based NPI assessment and modelling might support public health policy decision making by informing sequence and number of needed public health measures.

scholarly journals Online art therapy in elementary schools during COVID-19: results from a randomized cluster pilot and feasibility study and impact on mental health

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Catherine Malboeuf-Hurtubise ◽  
Terra Léger-Goodes ◽  
Geneviève A. Mageau ◽  
Geneviève Taylor ◽  
Catherine M. Herba ◽  
...  
Keyword(s):  
Mental Health ◽  
Elementary School ◽  
Art Therapy ◽  
Feasibility Study ◽  
School Children ◽  
Elementary School Children ◽  
Children’S Mental Health ◽  
Children's Mental Health ◽  
Sensitivity Analyses ◽  
The Impact

Abstract Background Emerging literature on the current COVID-19 crisis suggests that children may experience increased anxiety and depression as a result of the pandemic. To prevent such school and mental health-related problems, there is a timely need to develop preventive strategies and interventions to address potential negative impacts of COVID-19 on children’s mental health, especially in school settings. Results from previous child clinical research indicate that art-based therapies, including mindfulness-based art therapy, have shown promise to increase children’s well-being and reduce psychological distress. Objective The goal of the present pilot and feasibility study was to compare the impact of an emotion-based directed drawing intervention and a mandala drawing intervention, on mental health in elementary school children (N = 22), in the context of the COVID-19 pandemic. Both interventions were group-based and delivered online and remotely. A pilot study using a randomized cluster design was implemented to evaluate and compare both interventions in relation to child anxiety, depression, inattention and hyperactivity symptoms. Results Analyses of covariance revealed a significant effect of the type of drawing intervention on levels of inattention, after controlling for baseline levels. Participants in the emotion-based directed drawing group showed lower inattention scores at post-test, when compared to participants in the mandala group. Post-hoc sensitivity analyses showed significant decreases in pre-to-post scores for levels of hyperactivity for the complete sample. Conclusion Overall, results from this pilot and feasibility study showed that both an emotion-based directed drawing intervention and a mandala drawing intervention may be beneficial to improve mental health in elementary school children, in the context of the current COVID-19 pandemic. From a feasibility standpoint, results indicate that the implementation of both interventions online and remotely, through a videoconference platform, is feasible and adequate in school-based settings. Further work incorporating larger sample sizes, longitudinal data and ensuring sufficient statistical power is warranted to evaluate the long-term impact of both interventions on children’s mental health.

Gastrostomy Tubes Placed in Children With Neurologic Impairment: Associated Morbidity and Mortality

2021 ◽  
pp. 088307382110001
Author(s):  
Jody L. Lin ◽  
Joseph Rigdon ◽  
Keith Van Haren ◽  
MyMy Buu ◽  
Olga Saynina ◽  
...  
Keyword(s):  
Severe Pneumonia ◽  
Sensitivity Analyses ◽  
Tube Placement ◽  
Composite Outcome ◽  
Eligibility Criteria ◽  
Risk Of Death ◽  
Cox Proportional Hazard ◽  
Neurologic Impairment ◽  
Increased Risk ◽  
The Impact

Background: Gastrostomy tube (G-tube) placement for children with neurologic impairment with dysphagia has been suggested for pneumonia prevention. However, prior studies demonstrated an association between G-tube placement and increased risk of pneumonia. We evaluate the association between timing of G-tube placement and death or severe pneumonia in children with neurologic impairment. Methods: We included all children enrolled in California Children’s Services between July 1, 2009, and June 30, 2014, with neurologic impairment and 1 pneumonia hospitalization. Prior to analysis, children with new G-tubes and those without were 1:2 propensity score matched on sociodemographics, medical complexity, and severity of index hospitalization. We used a time-varying Cox proportional hazard model for subsequent death or composite outcome of death or severe pneumonia to compare those with new G-tubes vs those without, adjusting for covariates described above. Results: A total of 2490 children met eligibility criteria, of whom 219 (9%) died and 789 (32%) had severe pneumonia. Compared to children without G-tubes, children with new G-tubes had decreased risk of death (hazard ratio [HR] 0.47, 95% confidence interval [CI] 0.39-0.55) but increased risk of the composite outcome (HR 1.21, CI 1.14-1.27). Sensitivity analyses using varied time criteria for definitions of G-tube and outcome found that more recent G-tube placement had greater associated risk reduction for death but increased risk of severe pneumonia. Conclusion: Recent G-tube placement is associated with reduced risk of death but increased risk of severe pneumonia. Decisions to place G-tubes for pulmonary indications in children with neurologic impairment should weigh the impact of severe pneumonia on quality of life.

scholarly journals The impact of teaching on the duration of common urological operations

2016 ◽  
Vol 10 (5-6) ◽  
pp. 172 ◽  
Author(s):  
Blayne Welk ◽  
Jennifer Winick-Ng ◽  
Andrew McClure ◽  
Chris Vinden ◽  
Sumit Dave ◽  
...  
Keyword(s):  
Radical Prostatectomy ◽  
Negative Binomial ◽  
Negative Binomial Regression ◽  
Potential Effect ◽  
Sensitivity Analyses ◽  
Teaching Hospitals ◽  
Operative Duration ◽  
Open Radical Prostatectomy ◽  
Academic Hospitals ◽  
The Impact

Introduction: The ability of academic (teaching) hospitals to offer the same level of efficiency as non-teaching hospitals in a publicly funded healthcare system is unknown. Our objective was to compare the operative duration of general urology procedures between teaching and non-teaching hospitals. Methods: We used administrative data from the province of Ontario to conduct a retrospective cohort study of all adults who underwent a specified elective urology procedure (2002–2013). Primary outcome was duration of surgical procedure. Primary exposure was hospital type (academic or non-teaching). Negative binomial regression was used to adjust relative time estimates for age, comorbidity, obesity, anesthetic, and surgeon and hospital case volume.Results: 114 225 procedures were included (circumcision n=12 280; hydrocelectomy n=7221; open radical prostatectomy n=22 951; transurethral prostatectomy n=56 066; or mid-urethral sling n=15 707). These procedures were performed in an academic hospital in 14.8%, 13.3%, 28.6%, 17.1%, and 21.3% of cases, respectively. The mean operative duration across all procedures was higher in academic centres; the additional operative time ranged from 8.3 minutes (circumcision) to 29.2 minutes (radical prostatectomy). In adjusted analysis, patients treated in academic hospitals were still found to have procedures that were significantly longer (by 10‒21%). These results were similar in sensitivity analyses that accounted for the potential effect of more complex patients being referred to tertiary academic centres.Conclusions: Five common general urology operations take significantly longer to perform in academic hospitals. The reason for this may be due to the combined effect of teaching students and residents or due to inherent systematic inefficiencies within large academic hospitals.

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