Estimation of the Squirt-Flow Length Based on Crack Properties in Tight Sandstones

Tight sandstones have low porosity and permeability and strong heterogeneities with microcracks, resulting in small wave impedance contrasts with the surrounding rock and weak fluid-induced seismic effects, which make the seismic characterization for fluid detection and identification difficult. For this purpose, we propose a reformulated modified frame squirt-flow (MFS) model to describe wave attenuation and velocity dispersion. The squirt-flow length (R) is an important parameter of the model, and, at present, no direct method has been reported to determine it. We obtain the crack properties and R based on the DZ (David-Zimmerman) model and MFS model, and how these properties affect the wave propagation, considering ultrasonic experimental data of the Sichuan Basin. The new model can be useful in practical applications related to exploration areas.

Evaluation of thickened liquid viscoelasticity for a swallowing process using an inclined flow channel instrument

An inclined flow channel instrument that can be developed to be a structurally simple and easy-to-use rheometer was applied to control the thickness, specifically the viscosity and elasticity, of liquids thickened to support swallowing in nursing-care practice. Aqueous solutions containing salt or acid, which might be used as ingredients in drinks, were thickened with a commercial thickener. The thickener efficacy decreased because of the salt or acid in liquid phase. Analysis of the flows in the instrument by experimentation yielded a dimensionless relation representing changes of the Deborah number in the flow process, as indicated by the relative flow length, considering the shear rate in oral processing. One unique methodology to evaluate the viscoelasticities of thickened liquids during the swallowing process was presented utilizing the measurements such as elapsed time and velocity in the instrument.

Menstrual cycle among adolescents: girls’ awareness and influence of age at menarche and overweight

Objective: To characterize the menstrual cycle (regularity and menstrual flow length), the prevalence of dysmenorrhea and self-monitoring of the cycle in students from Lisbon region, and explore the effect of chronological age, age at menarche and body mass index (BMI) on menstrual disorders. Methods: This is a cross-sectional study with 848 girls aged 12–18 years. A questionnaire about the sociodemographic context and characteristics of the menstrual cycle, and weight and height measures were assessed. BMI was classified according to International Obesity Taskforce criteria. A descriptive analysis of the variables was made, and Odds Ratios (ORs) and 95% confidence intervals (95%CIs) were determined. Results: Mean age at menarche was 12.4 years and mean BMI was 22.0kg/m2. Among adolescents, 59% have regular menstrual cycle, 83% have menstrual flow length of ≤6 days. 88% suffered from dysmenorrhea, among which 8,7% declare absenteeism from school and 49% took pain medication, and 65% self-monitor their menstrual cycle. Higher maternal education was associated with a higher self-monitoring of menstrual cycle among the sample (OR 1.60; 95%CI 1.15–2.17). Girls with menarche <12 years-of-age are more likely to have menstrual flow length of >6 days (OR 1.73; 95%CI 1.19–2.51) and dysmenorrhea (OR 1.87; 95%CI 1.11–3.16) than those with menarche ≥12 years-of-age. No significant association between BMI and menstrual cycle variables was observed. Conclusions: The results suggest that menstrual disorders are frequent and may be associated with early menarche, but not with BMI. It is important to encourage self-monitoring of the menstrual cycle to detect menstrual disorders timely and promote health and well-being.

Impact of Data Processing and DTM Resolution on Determining of Small Erosional Landforms

Small erosional landforms are characterised by a dynamics closely related to the occurrence and changes in precipitation and water flowing down the slopes. Triggered by water, the erosion processes are controlled by the other environmental conditions like slope gradient, lithology, land cover and land use. Studying the changes in the topography gives information about the spatiotemporal dynamics of erosion and can contribute to a more effective assessment of erosion susceptibility and mitigation measures at the earliest stage of the process development. Usually in the initial stages, the changes in the topography are hardly noticeable and using high resolution digital terrain models (DTMs) is of high importance. In this relation, the aim of the current research is to determine to what extent the resolution of the models influences the results of delineating the flow lines, rills and gullies. For this purpose, a terrain survey was carried out and data was acquired by UAS (uncrewed aerial system) DJI Phantom 4RTK. DTMs in horizontal resolution of 0.05, 0.1, 0.2, 0.5 and 1 m are created and analysed. Special attention is given to the analysis of surface curvature as an indicator for flow convergence and divergence. The research is done on a slope area covered mainly by grass and some rare bushes and trees. Despite the observed variations, the results show a general trend of decrease in the flow length with decreasing DTMs resolution. Considering the plan curvature and concave areas, the differences are smallest between the models with cell size 0.1 and 0.2 m.

The Influence of Surface Quality on Flow Length and Micro-Mechanical Properties of Polycarbonate

This study describes the influence of polymer flow length on mechanical properties of tested polymer, specifically polycarbonate. The flow length was examined in a spiral shaped mould. The mould cavity’s surface was machined by several methods, which led to differing roughness of the surface. The cavity was finished by milling, grinding and polishing. In order to thoroughly understand the influence of the mould surface quality on the flow length, varying processing parameters, specifically the pressure, were used. The polymer part was divided into several segments, in which the micro-mechanical properties, such as hardness and indentation modulus were measured. The results of this study provide interesting data concerning the flow length, which was up to 3% longer for rougher surfaces, but shorter in cavities with polished surface. These results are in disagreement with the commonly practiced theory, which states that better surface quality leads to greater flow length. Furthermore, evaluation of the micro-mechanical properties measured along the flow path demonstrated significant variance in researched properties, which increased by 35% (indentation hardness) and 86% by indentation modulus) in latter segments of the spiral in comparison with the gate.

Unprecedented Retention Capabilities of Extensive Green Roofs—New Design Approaches and an Open-Source Model

Green roofs are a proven measure to increase evapotranspiration at the expense of runoff, thus complementing contemporary stormwater management efforts to minimize pluvial flooding in cities. This effect has been quantified by numerous studies, ranging from experimental field campaigns to modeling experiments and even combinations of both. However, up until now, most green roof studies consider standard types of green roof dimensions, thus neglecting varying flow length in the substrate. For the first time, we present a comprehensive investigation of green roofs that involves artificial rainfall experiments under laboratory conditions (42 experiments in total). We consider varying flow length and slope. The novelty lies especially in the consideration of flow lengths beyond 5 m and non-declined roofs. This experimental part is complemented by numerical modeling, employing the open-source Catchment Modeling Framework (CMF). This is set-up for Darcy and Richards flow in the green roof and calibrated utilizing a multi-objective approach, considering both runoff and hydraulic head. The results demonstrate that through maximizing flow length and minimizing slope, the runoff coefficient (i.e., percentage of rainfall that becomes runoff) for a 100 years design rainfall is significantly decreased: from ~30% to values below 10%. These findings are confirmed through numerical modeling, which proves its value in terms of achieved model skill (Kling-Gupta Efficiency ranging from 0.5 to 0.95 with a median of 0.78). Both the experimental data and the numerical model are published as open data and open-source software, respectively. Thus, this study provides new insights into green roof design with high practical relevance, whilst being reproducible.

Fluidity Investigation of Pure Al and Al-Si Alloys

Fluidity tests of pure aluminum 1070 and Al-Si alloys with Si contents of up to 25% were conducted using a die cast machine equipped with a spiral die. The effects of the channel gap, die temperature, and injection speed on the fluidity were investigated. When the channel gap was small (0.5 mm), the flow length of the 1070 was minimized, and the fluidity increased monotonically at a gradual rate with increasing Si content. In contrast, larger gaps yielded convex fluidity–Si content curves. Additionally, heating the die had less of an influence on the fluidity of the 1070 than on that of the Al-Si alloy. These results are discussed in the context of the peeling of the solidification layer from the die based on the thicknesses of foils and strips cast by melt spinning and roll casting, respectively. At lower Si contents, heat shrinkage was greater and the latent heat was lower. When the heat shrinkage was greater, the solidification layer began to peel earlier, and the heat transfer between the solidification layer and the die became smaller. As a result, the fluidity of the 1070 was greatest when the channel gap was 0.8 mm.

Dry granular masses impacting on rigid obstacles: numerical analysis and theoretical modelling

The assessment of the time evolution of the impact force exerted by dry flowing masses on rigid obstacles is mandatory for the dynamic design of sheltering structures and the evaluation of the vulnerability of existing structures. In this paper, the results of an extensive numerical campaign performed by employing a discrete element method (DEM) code are presented and the role of different geometrical factors (flow length, height and front inclination) and state parameters (porosity and velocity) on the impact force–time evolution is investigated. The impact process is studied to correlate local information with the macroscopic response and a physically based force–time function, generalising the formula already introduced by the authors for the assessment of maximum impact force, in which each parameter is correlated with the previously mentioned factors, is proposed.

Topographical Characteristics of Frequent Inland Water Flooding Areas in Tangerang City, Indonesia

The methodology examined for this study was based on statistical analyses and GIS computations of frequent inland water flooding areas in Tangerang city, Indonesia during 2008–2015. Primary data used for this study were inland water flooding records from Tangerang city government and an approximately 90 m Merit DEM. We extracted the topographical characteristics of frequent inland water flooding areas and used principal component analysis to find its main characteristics. Results show that frequent inland water flooding areas in Tangerang emerged because of a slope in the upstream condition, the correlation between concave and flow length conditions, correlation of the slope condition and distance to a river, and relations among flow length in upstream characteristics and distance to a pond. Furthermore, a principal component score of frequent inland water flooding areas and other areas in the city was compared with measure similarity. This method correctly identified 71% of frequent inland water flooding areas. Also, 74% of one-time inland water flooding areas were classified as locations with high topographical similarity. Furthermore, field surveys indicated that the remaining 29% of frequent inland water flooding areas had low topographical similarity because of anthropogenic factors.