An eco-friendly epoxy polymer binder for the treatment of Tunisian harbor sediments: Laboratory investigations for beneficial reuse

2020 ◽  
Vol 38 (8) ◽  
pp. 876-885 ◽  
Author(s):  
Afef Zouch ◽  
Yannick Mamindy-Pajany ◽  
Ilyas Ennahal ◽  
Nor-Edine Abriak ◽  
Mohamed Ksibi
Keyword(s):  
Construction Materials ◽  
Environmental Parameters ◽  
Dry Mass ◽  
Polymer Binder ◽  
Point Of View ◽  
Experimental Investigations ◽  
Geochemical Properties ◽  
Beneficial Reuse ◽  
Sediment Fraction

The management of dredged sediments poses serious environmental and economic problems because of their geochemical properties and in particular their pollutant content. In this research, marine sediments from Tunisian harbors were collected to study their beneficial reuse as construction materials using an eco-friendly polymer binder. Experimental investigations include the determination of physicochemical, mineralogical, and environmental parameters of sediments from the Sidi Mansour and Sidi Youssef areas in Tunisia. Prismatic mortar samples (4 × 4 × 16 cm) were prepared at laboratory scale using normalized sand and epoxy resin. Then their composition was modified by including a sediment fraction in the substitution of sand at rates ranging from 10 to 50% in dry mass. After a 7-day curing period, mortar samples were submitted to mechanical, physicochemical, and environmental analyses. Mortar samples including sediment fractions displayed lower strength than sand mortar used as control. This result is explained by the increase of porosity values in the mortar samples when sediment samples were incorporated. A positive relationship between porosity and compressive strength values was evidenced, suggesting that the compactness of granular skeleton could play an important role in the preparation of materials. From an environmental point of view, the mortar samples containing sediment fractions showed relatively low leaching levels, which confirms their suitability for the manufacturing of construction materials.

scholarly journals Influence of surface roughness on fatigue life of machine elements – the development in experimental investigations and simulations

Mechanik ◽  
2019 ◽  
Vol 92 (5-6) ◽  
pp. 307-313 ◽  
Author(s):  
Wit Grzesik
Keyword(s):  
Surface Roughness ◽  
Fatigue Life ◽  
Construction Materials ◽  
Fatigue Tests ◽  
Experimental Investigations ◽  
Fundamental Information ◽  
Aerospace Alloys ◽  
Machine Elements ◽  
Effect Of Surface

In this paper fundamental information on the influence of surface roughness on fatigue life/limit stresses of machine elements made of different construction materials using different machining/manufacturing processes are presented. The rules for the assessment of surface finish influence represented by the set of microscopic notches on the real machined surfaces, which allow the determination of the stress concentration factor and the correction of a fatigue life limit, are provided. The results of fatigue tests are compared with computed data and predictions using FEM based simulations. The effect of surface discontinues resulting from surface roughness are related to machine elements made of steels, aluminium alloys, aerospace alloys – titanium and nickel based superalloys and composite reinforced by graphite fibres.

scholarly journals Evaluation of the Ability to Accurately Produce Angular Details by 3D Printing of Plastic Parts

Machines ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 150
Author(s):  
Andrei Marius Mihalache ◽  
Gheorghe Nagîț ◽  
Laurențiu Slătineanu ◽  
Adelina Hrițuc ◽  
Angelos Markopoulos ◽  
...  
Keyword(s):  
3D Printing ◽  
Point Of View ◽  
Vertex Angle ◽  
Function Type ◽  
Constant Height ◽  
3D Printers ◽  
3D Printed ◽  
Mathematical Processing ◽  
Plastic Parts

3D printing is a process that has become widely used in recent years, allowing the production of parts with relatively complicated shapes from metallic and non-metallic materials. In some cases, it is challenging to evaluate the ability of 3D printers to make fine details of parts. For such an assessment, the printing of samples showing intersections of surfaces with low angle values was considered. An experimental plan was designed and materialized to highlight the influence of different factors, such as the thickness of the deposited material layer, the printing speed, the cooling and filling conditions of the 3D-printed part, and the thickness of the sample. Samples using areas in the form of isosceles triangles with constant height or bases with the same length, respectively, were used. The mathematical processing of the experimental results allowed the determination of empirical mathematical models of the power-function type. It allowed the detection of both the direction of actions and the intensity of the influence exerted by the input factors. It is concluded that the strongest influence on the printer’s ability to produce fine detail, from the point of view addressed in the paper, is exerted by the vertex angle, whose reduction leads to a decrease in printing accuracy.

Determination of a Rubber-Like Material Model as an Inverse Problem

2011 ◽  
Vol 70 ◽  
pp. 225-230 ◽  
Author(s):  
Agnieszka Derewonko ◽  
Andrzej Kiczko
Keyword(s):  
Selection Process ◽  
Axial Stress ◽  
Constitutive Models ◽  
Material Model ◽  
Polyester Fabric ◽  
Point Of View ◽  
Air Cushion ◽  
Ill Conditioning ◽  
Stress States

The purpose of this paper is to describe the selection process of a rubber-like material model useful for simulation behaviour of an inflatable air cushion under multi-axial stress states. The air cushion is a part of a single segment of a pontoon bridge. The air cushion is constructed of a polyester fabric reinforced membrane such as Hypalon®. From a numerical point of view such a composite type poses a challenge since numerical ill-conditioning can occur due to stiffness differences between rubber and fabric. Due to the analysis of the large deformation dynamic response of the structure, the LS-Dyna code is used. Since LS-Dyna contains more than two-hundred constitutive models the inverse method is used to determine parameters characterizing the material on the base of results of the experimental test.

scholarly journals Machine Learning Approaches for Prediction of the Compressive Strength of Alkali Activated Termite Mound Soil

2021 ◽  
Vol 11 (11) ◽  
pp. 4754
Author(s):  
Assia Aboubakar Mahamat ◽  
Moussa Mahamat Boukar ◽  
Nurudeen Mahmud Ibrahim ◽  
Tido Tiwa Stanislas ◽  
Numfor Linda Bih ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Construction Materials ◽  
Curing Temperature ◽  
Sustainable Construction ◽  
Support Vector ◽  
Learning Approaches ◽  
Artificial Neural Network Ann ◽  
Curing Regime ◽  
Alkali Activated

Earth-based materials have shown promise in the development of ecofriendly and sustainable construction materials. However, their unconventional usage in the construction field makes the estimation of their properties difficult and inaccurate. Often, the determination of their properties is conducted based on a conventional materials procedure. Hence, there is inaccuracy in understanding the properties of the unconventional materials. To obtain more accurate properties, a support vector machine (SVM), artificial neural network (ANN) and linear regression (LR) were used to predict the compressive strength of the alkali-activated termite soil. In this study, factors such as activator concentration, Si/Al, initial curing temperature, water absorption, weight and curing regime were used as input parameters due to their significant effect in the compressive strength. The experimental results depict that SVM outperforms ANN and LR in terms of R2 score and root mean square error (RMSE).

Resistance to Outflow of Cerebrospinal Fluid Determined by Bolus Injection Technique and Constant Rate Steady State Infusion in Humans

Neurosurgery ◽  
1985 ◽  
Vol 16 (3) ◽  
pp. 336-340 ◽  
Author(s):  
Michael Kosteljanetz
Keyword(s):  
Cerebrospinal Fluid ◽  
Steady State ◽  
Bolus Injection ◽  
Point Of View ◽  
Injection Technique ◽  
Communicating Hydrocephalus ◽  
Constant Rate ◽  
High Degree ◽  
Infusion Technique

Abstract Two methods for the determination of resistance to the outflow of cerebrospinal fluid, the bolus injection technique and the constant rate steady state infusion technique, were compared. Thirty-two patients with a variety of intracranial diseases (usually communicating hydrocephalus) were studied. There was a high degree of correlation between the resistance values obtained with the two methods, but values based on the bolus injection technique were systematically and statistically significantly lower than those obtained with the constant rate infusion test. From a practical point of view. both methods were found to be applicable in a clinical setting.

scholarly journals Implementation of BIM Modelling and Simulation Tools in Reducing Annual Energy Consumption of Multifamily Dwellings

2020 ◽  
Vol 170 ◽  
pp. 01002
Author(s):  
Subbarao Yarramsetty ◽  
MVN Siva Kumar ◽  
P Anand Raj
Keyword(s):  
Energy Efficient ◽  
Energy Use ◽  
Construction Materials ◽  
Residential Building ◽  
Energy Simulation ◽  
Point Of View ◽  
Rotational Angle ◽  
Existing Building ◽  
Simulation Tools ◽  
Efficient Option

In current research, building modelling and energy simulation tools were used to analyse and estimate the energy use of dwellings in order to reduce the annual energy use in multifamily dwellings. A three-story residential building located in Kabul city was modelled in Revit and all required parameters for running energy simulation were set. A Total of 126 experiments were conducted to estimate annual energy loads of the building. Different combinations from various components such as walls, roofs, floors, doors, and windows were created and simulated. Ultimately, the most energy efficient option in the context of Afghan dwellings was figured out. The building components consist of different locally available construction materials currently used in buildings in Afghanistan. Furthermore, the best energy efficient option was simulated by varying, building orientation in 15-degree increments and glazing area from 10% to 60% to find the most energy efficient combination. It was found that combination No. 48 was best option from energy conservation point of view and 120-degree rotational angle from north to east, of the existing building was the most energy-efficient option. Also, it was observed that 60% glazing area model consumed 24549 kWh more electricity compared to the one with 10% glazing area.

Determination of In-plane Shear Strength of Unidirectional Composite Materials Using the Off-axis Three-point Flexure and Off-axis Tensile Tests

2010 ◽  
Vol 44 (21) ◽  
pp. 2487-2507 ◽  
Author(s):  
G. Vargas ◽  
F. Mujika
Keyword(s):  
Shear Strength ◽  
Composite Materials ◽  
Tensile Tests ◽  
Unidirectional Composite ◽  
Point Of View ◽  
Experimental Point ◽  
Plane Shear ◽  
Lift Off ◽  
Flexure Test

The aim of this work is to compare from an experimental point of view the determination of in-plane shear strength of unidirectional composite materials by means of two off-axis tests: three-point flexure and tensile. In the case of the off-axis three-point flexure test, the condition of small displacements and the condition of lift-off between the specimen and the fixture supports have been taken into account. Some considerations regarding stress and displacement fields are presented. The in-plane shear characterization has been performed on a carbon fiber reinforced unidirectional laminate with several fiber orientation angles: 10°, 20°, 30°, and 45°. Test conditions for both off-axis experimental methods, in order to ensure their applicability, are presented. Off-axis flexure test is considered more suitable than off-axis tensile test for the determination of in-plane shear strength.

scholarly journals Evaluation of Usefulness of the Designed Laboratory Photobioreactor for Microalgae Cultivation in Controlled Conditions

2016 ◽  
Vol 20 (1) ◽  
pp. 13-22
Author(s):  
Beata Brzychczyk ◽  
Zbigniew Kowalczyk ◽  
Jan Giełżecki
Keyword(s):  
Culture Medium ◽  
Dry Mass ◽  
Biomass Growth ◽  
Microalgae Cultivation ◽  
Freshwater Microalgae ◽  
Laboratory Conditions ◽  
Medium Concentration ◽  
Controlled Conditions ◽  
The Impact

AbstractThe objective of the paper was to analyse the use of the designed photobioreactor for freshwater microalgae cultivation in the controlled laboratory conditions. The work covered the design and construction of photobioreactors (PBR) and setting up comparative cultivations of freshwater microalgae chlorelli vulgaris along with determination of the biomass growth intensity for a varied amount of supplied culture medium. It was found out that the constructed PBR may be used for microalgae cultivation in the controlled conditions. The impact of the culture medium amount on the growth of chlorelli vulgaris was proved. As a result of the increase of culture medium concentration to 30.1-120.4 ml·l−1 of water, dry mass in photobioreactorsincreased respectively from 1.33 g·dm−3 to 4.68 g·dm−3.

scholarly journals Thin-film-induced morphological instabilities over calcite surfaces

2015 ◽  
Vol 471 (2176) ◽  
pp. 20150031 ◽  
Author(s):  
R. Vesipa ◽  
C. Camporeale ◽  
L. Ridolfi
Keyword(s):  
Morphological Evolution ◽  
Water Film ◽  
Environmental Parameters ◽  
Climatic Conditions ◽  
Point Of View ◽  
Theoretical Point ◽  
Carbon Dioxide Transport ◽  
Physical Mechanisms ◽  
Water Films ◽  
Dissolved Ions

Precipitation of calcium carbonate from water films generates fascinating calcite morphologies that have attracted scientific interest over past centuries. Nowadays, speleothems are no longer known only for their beauty but they are also recognized to be precious records of past climatic conditions, and research aims to unveil and understand the mechanisms responsible for their morphological evolution. In this paper, we focus on crenulations, a widely observed ripple-like instability of the the calcite–water interface that develops orthogonally to the film flow. We expand a previous work providing new insights about the chemical and physical mechanisms that drive the formation of crenulations. In particular, we demonstrate the marginal role played by carbon dioxide transport in generating crenulation patterns, which are indeed induced by the hydrodynamic response of the free surface of the water film. Furthermore, we investigate the role of different environmental parameters, such as temperature, concentration of dissolved ions and wall slope. We also assess the convective/absolute nature of the crenulation instability. Finally, the possibility of using crenulation wavelength as a proxy of past flows is briefly discussed from a theoretical point of view.

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