Search results for: rock mechanical studies

Authors: Slim Souissi, Mohamed Ben Amar, Nesrine Bouhamed, Pierre Marechal

Abstract:

The bio-composites development from biodegradable materials and natural fibers has a growing interest in the science of composite materials. The present work was conducted as part of a cooperation project between the Sfax University and the Havre University. This work consists in developing and monitoring the properties of a composite material of olive flour wood with a polymer matrix (urea formaldehyde). For this, ultrasonic non-destructive and destructive methods of characterization were used to optimize the mechanical and acoustic properties of the studied material based on the elaboration parameters.

Keywords: bio-composite, olive flour wood, polymer matrix, ultrasonic methods, mechanical properties

Procedia PDF Downloads 485

Authors: Samaneh Yavari, Christiane Pferrer, Elisabeth Engelke, Alexander Starke, Juergen Rehage

Abstract:

Background: Three nociceptive thresholds of thermal, electrical, and mechanical thresholds commonly use to evaluate the local anesthesia in many species, for instance, cow, horse, cat, dog, rabbit, and so on. Due to the lack of investigations to evaluate and/or validate such those nociceptive thresholds, our plan was the comparison of two-foot local anesthesia methods of Intravenous Regional Anesthesia (IVRA) and our modified four-point Nerve Block Anesthesia (NBA). Materials and Methods: Eight healthy nonpregnant nondairy Holstein Frisian cows in a cross-over study design were selected for this study. All cows divided into two different groups to receive two local anesthesia techniques of IVRA and our modified four-point NBA. Three thermal, electrical, and mechanical force and pinpricks were applied to evaluate the quality of local anesthesia methods before and after local anesthesia application. Results: The statistical evaluation demonstrated that our four-point NBA has a qualification to select as a standard foot local anesthesia. However, the recorded results of our study revealed no significant difference between two groups of local anesthesia techniques of IVRA and modified four-point NBA related to quality and duration of anesthesia stimulated by electrical, mechanical and thermal nociceptive stimuli. Conclusion and discussion: All three nociceptive threshold stimuli of electrical, mechanical and heat nociceptive thresholds can be applied to measure and evaluate the efficacy of foot local anesthesia of dairy cows. However, our study revealed no superiority of those three nociceptive methods to evaluate the duration and quality of bovine foot local anesthesia methods. Veterinarians to investigate the duration and quality of their selected anesthesia method can use any of those heat, mechanical, and electrical methods.

Keywords: mechanical, thermal, electrical threshold, IVRA, NBA, hind limb, dairy cow

Procedia PDF Downloads 240

Authors: Isomar Lima da Silva, Alcilene Batalha Pontes, Aristeu Jonatas Leite de Oliveira, Roberto Maia Augusto

Abstract:

Context: Mechanical ventilators are medical devices that help provide oxygen and ventilation to patients with respiratory difficulties. This equipment consists of a manual breathing unit that can be operated by a doctor or nurse and a mechanical ventilator that controls the airflow and pressure in the patient's respiratory system. This type of ventilator is commonly used in emergencies and intensive care units where it is necessary to provide breathing support to critically ill or injured patients. Objective: In this context, this work aims to develop a reliable and low-cost mechanical ventilator to meet the demand of hospitals in treating people affected by Covid-19 and other severe respiratory diseases, offering a chance of treatment as an alternative to mechanical ventilators currently available in the market. Method: The project presents the development of a low-cost auxiliary ventilator with a controlled ventilatory system assisted by integrated hardware and firmware for respiratory cycle control in non-invasive mechanical ventilation treatments using a manual artificial respiration unit. The hardware includes pressure sensors capable of identifying positive expiratory pressure, peak inspiratory flow, and injected air volume. The embedded system controls the data sent by the sensors. It ensures efficient patient breathing through the operation of the sensors, microcontroller, and actuator, providing patient data information to the healthcare professional (system operator) through the graphical interface and enabling clinical parameter adjustments as needed. Results: The test data of the developed mechanical ventilator presented satisfactory results in terms of performance and reliability, showing that the equipment developed can be a viable alternative to commercial mechanical ventilators currently available, offering a low-cost solution to meet the increasing demand for respiratory support equipment.

Keywords: mechanical fans, breathing, medical equipment, COVID-19, intensive care units

Procedia PDF Downloads 57

Authors: Can Otuzbir

Abstract:

It is one of the most difficult areas of civil engineering to provide long-lasting structures with the rapid development of concrete and reinforced concrete structures. Concrete is a living material, and the structure where the concrete is located is constantly exposed to external influences. One of these effects is reinforcement corrosion. Reinforcement corrosion of reinforced concrete structures leads to a significant decrease in the carrying capacity of the structural elements, as well as reduced service life. It is undesirable that the service life should be completed sooner than expected. In recent years, advances in glass fiber technology and its use with concrete have developed rapidly. As a result of inability to protect steel reinforcements against corrosion, fiberglass reinforcements have started to be investigated as an alternative material to steel reinforcements, and researches and experimental studies are still continuing. Glass fiber reinforcements have become an alternative material to steel reinforcement because they are resistant to corrosion, lightweight and simple to install compared to steel reinforcement. Glass fiber reinforcements are not corroded and have higher tensile strength, longer life, lighter and insulating properties compared to steel reinforcement. In experimental studies, glass fiber reinforcements have been shown to show superior mechanical properties similar to beams produced with steel reinforcement. The performance of long-term use of glass fiber fibers continues with accelerated experimental studies.

Keywords: glass fiber polymer reinforcement, steel fiber concrete, ultra high performance concrete, bending, GFRP

Procedia PDF Downloads 117

Authors: G. Vishnu, T. V. Bharat

Abstract:

Rainfall plays a major role in the stability of natural slopes in tropical and subtropical regions. These slopes usually have high slope angles and are stable during the dry season. The critical rainfall intensity that might trigger a landslide may not be the highest rainfall. In addition to geological discontinuities and anthropogenic factors, water content, suction, and hydraulic conductivity also play a role. A thorough geotechnical investigation with the principles of unsaturated soil mechanics is required to predict the failures in these cases. The study discusses three landslide events that had occurred in residual hills of Guwahati, India. Rainfall data analysis, history image analysis, land use, and slope maps of the region were analyzed and discussed. The landslide occurred on June (24, 26, and 28) 2020, on the respective sites, but the highest rainfall was on June (6 and 17) 2020. The factors that lead to the landslide occurrence is the combination of critical events initiated with rainfall, causing a reduction in suction. The sites consist of a mixture of rocks and soil. The slope failure occurs due to the saturation of the soil layer leading to loss of soil strength resulting in the flow of the entire soil rock mass. The land-use change, construction activities, other human and natural activities that lead to faster disintegration of rock mass may accelerate the landslide events. Landslides in these slopes are inevitable, and the development of an early warning system (EWS) to save human lives and resources is a feasible way. The actual time of failure of a slope can be better predicted by considering all these factors rather than depending solely on the rainfall intensities. An effective EWS is required with less false alarms in these regions by proper instrumentation of slope and appropriate climatic downscaling.

Keywords: early warning system, historic image analysis, slope instrumentation, unsaturated soil mechanics

Procedia PDF Downloads 107

Authors: Quentin C.P. Bourgogne, Vanessa Bouchart, Pierre Chevrier, Emmanuel Dattoli

Abstract:

This study presents an experimental and theoretical work conducted on a PolyPhenylene Sulfide reinforced with 40%wt of short glass fibers (PPS GF40) and its matrix. Thermoplastics are widely used in the automotive industry to lightweight automotive parts. The replacement of metallic parts by thermoplastics is reaching under-the-hood parts, near the engine. In this area, the parts are subjected to high temperatures and are immersed in cooling liquid. This liquid is composed of water and glycol and can affect the mechanical properties of the composite. The aim of this work was thus to quantify the evolution of mechanical properties of the thermoplastic composite, as a function of temperature and liquid aging effects, in order to develop a reliable design of parts. An experimental campaign in the tensile mode was carried out at different temperatures and for various glycol proportions in the cooling liquid, for monotonic and cyclic loadings on a neat and a reinforced PPS. The results of these tests allowed to highlight some of the main physical phenomena occurring during these solicitations under tough hydro-thermal conditions. Indeed, the performed tests showed that temperature and liquid cooling aging can affect the mechanical behavior of the material in several ways. The more the cooling liquid contains water, the more the mechanical behavior is affected. It was observed that PPS showed a higher sensitivity to absorption than to chemical aggressiveness of the cooling liquid, explaining this dominant sensitivity. Two kinds of behaviors were noted: an elasto-plastic type under the glass transition temperature and a visco-pseudo-plastic one above it. It was also shown that viscosity is the leading phenomenon above the glass transition temperature for the PPS and could also be important under this temperature, mostly under cyclic conditions and when the stress rate is low. Finally, it was observed that soliciting this composite at high temperatures is decreasing the advantages of the presence of fibers. A new phenomenological model was then built to take into account these experimental observations. This new model allowed the prediction of the evolution of mechanical properties as a function of the loading environment, with a reduced number of parameters compared to precedent studies. It was also shown that the presented approach enables the description and the prediction of the mechanical response with very good accuracy (2% of average error at worst), over a wide range of hydrothermal conditions. A temperature-humidity equivalence principle was underlined for the PPS, allowing the consideration of aging effects within the proposed model. Then, a limit of improvement of the reachable accuracy was determinate for all models using this set of data by the application of an artificial intelligence-based model allowing a comparison between artificial intelligence-based models and phenomenological based ones.

Keywords: aging, analytical modeling, mechanical testing, polymer matrix composites, sequential model, thermomechanical

Procedia PDF Downloads 105

Authors: Rayan B. M. Ameen, Ian P. Jones, Yu Lung Chiu

Abstract:

Single alpha-beta colony micro-pillars have been manufactured from a polycrystalline commercial Ti-6Al-4V sample using Focused Ion Beam (FIB). Each pillar contained two alpha lamellae separated by a thin fillet of beta phase. A nano-indenter was then used to conduct uniaxial micro-compression tests on Ti alloy single crystals, using a diamond flat tip as a compression platen. By controlling the crystal orientation along the micro-pillar using Electron back scattering diffraction (EBSD) different slip systems have been selectively activated. The advantage of the micro-compression method over conventional mechanical testing techniques is the ability to localize a single crystal volume which is characterizable after deformation. By matching the stress-strain relations resulting from micro-compression experiments to TEM (Transmission Electron Microscopy) studies of slip transmission mechanisms through the α-β interfaces, some proper constitutive material parameters such as the role of these interfaces in determining yield, strain-hardening behaviour, initial dislocation density and the critical resolved shear stress are suggested.

Keywords: α/β-Ti alloy, focused ion beam, micro-mechanical test, nano-indentation, transmission electron diffraction, plastic flow

Procedia PDF Downloads 370

Authors: Abdullah Kaymakci, Daniel M. Madyira, Ntokozo Nkwanyana

Abstract:

The effect of metal transfer modes on mechanical properties of welded 3CR12 stainless steel were investigated. This was achieved by butt welding 10 mm thick plates of 3CR12 in different positions while varying the welding positions for different metal transfer modes. The ASME IX: 2010 (Welding and Brazing Qualifications) code was used as a basis for welding variables. The material and the thickness of the base metal were kept constant together with the filler metal, shielding gas and joint types. The effect of the metal transfer modes on the microstructure and the mechanical properties of the 3CR12 steel was then investigated as it was hypothesized that the change in welding positions will affect the transfer modes partly due to the effect of gravity. The microscopic examination revealed that the substrate was characterized by dual phase microstructure, that is, alpha phase and beta phase grain structures. Using the spectroscopic examination results and the ferritic factor calculation had shown that the microstructure was expected to be ferritic-martensitic during air cooling process. The tested tensile strength and Charpy impact energy were measured to be 498 MPa and 102 J which were in line with mechanical properties given in the material certificate. The heat input in the material was observed to be greater than 1 kJ/mm which is the limiting factor for grain growth during the welding process. Grain growths were observed in the heat affected zone of the welded materials. Ferritic-martensitic microstructure was observed in the microstructure during the microscopic examination. The grain growth altered the mechanical properties of the test material. Globular down hand had higher mechanical properties than spray down hand. Globular vertical up had better mechanical properties than globular vertical down.

Keywords: welding, metal transfer modes, stainless steel, microstructure, hardness, tensile strength

Procedia PDF Downloads 245

Authors: Erion Luga, Aksel Seitllari, Kemal Pervanqe

Abstract:

This study investigates the relation between physical and mechanical properties of concrete paving stones using neuro-fuzzy approach. For this purpose 200 samples of concrete paving stones were selected randomly from different sources. The first phase included the determination of physical properties of the samples such as water absorption capacity, porosity and unit weight. After that the indirect tensile strength test and compressive strength test of the samples were performed. İn the second phase, adaptive neuro-fuzzy approach was employed to simulate nonlinear mapping between the above mentioned physical properties and mechanical properties of paving stones. The neuro-fuzzy models uses Sugeno type fuzzy inference system. The models parameters were adapted using hybrid learning algorithm and input space was fuzzyfied by considering grid partitioning. It is concluded based on the observed data and the estimated data through ANFIS models that neuro-fuzzy system exhibits a satisfactory performance.

Keywords: paving stones, physical properties, mechanical properties, ANFIS

Procedia PDF Downloads 326

Authors: Louis N. Y. Wong

Abstract:

En-echelon fractures are commonly found in rocks, which appear as a special set of regularly oriented and spaced fractures. By using both experimental and numerical approaches, this study investigates the interaction among them, and how this interaction finally contributes to the development of a shear rupture (fault), especially in brittle natural rocks. Firstly, uniaxial compression tests are conducted on marble specimens containing en-echelon flaws. The latter is cut by using the water abrasive jet into the rock specimens. The fracturing processes of these specimens leading to the formation of a fault are observed in detail by the use of a high speed camera. The influences of the flaw geometry on the production of tensile cracks and shear cracks, which in turn dictate the coalescence patterns of the entire set of en-echelon flaws are comprehensively studied. Secondly, a numerical study based on a recently developed contact model, flat-joint contact model using the discrete element method (DEM) is carried out to model the present laboratory experiments. The numerical results provide a quantitative assessment of the interaction of en-echelon flaws. Particularly, the evolution of the stress field, as well as the characteristics of new crack initiation, propagation and coalescence associated with the generation of an eventual shear rupture are studied in detail. The numerical results are found to agree well with the experimental results obtained in both microscopic and macroscopic observations.

Keywords: discrete element method, en-echelon flaws, fault, marble

Procedia PDF Downloads 251

Authors: Sami Aboujafar

Abstract:

Oil recovery in petroleum reservoirs is greatly affected by fluid-rock and fluid-fluid interactions. These interactions directly control rock wettability, capillary pressure and relative permeability curves. Laboratory core-floods and centrifuge experiments were conducted on sandstone and carbonate cores to study the effect of low and high brine salinity and viscosity and oil viscosity on residual saturations and relative permeability. Drainage and imbibition relative permeability in two phase system were measured, refined lab oils with different viscosities, heavy and light, and several brine salinities were used. Sensitivity analysis with different values for the salinity and viscosity of the fluids,, oil and water, were done to investigate the effect of these properties on water/oil relative permeability, residual oil saturation and oil recovery. Experiments were conducted on core material from viscous/heavy and light oil fields. History matching core flood simulator was used to study how the relative permeability curves and end point saturations were affected by different fluid properties using several correlations. Results were compared with field data and literature data. The results indicate that there is a correlation between the oil viscosity and/or brine salinity and residual oil saturation and water relative permeability end point. Increasing oil viscosity reduces the Krw@Sor and increases Sor. The remaining oil saturation from laboratory measurements might be too high due to experimental procedures, capillary end effect and early termination of the experiment, especially when using heavy/viscous oil. Similarly the Krw@Sor may be too low. The effect of wettability on the observed results is also discussed. A consistent relationship has been drawn between the fluid parameters, water/oil relative permeability and residual saturations, and a descriptor may be derived to define different flow behaviors. The results of this work will have application to producing fields and the methodologies developed could have wider application to sandstone and carbonate reservoirs worldwide.

Keywords: history matching core flood simulator, oil recovery, relative permeability, residual saturations

Procedia PDF Downloads 325

Authors: B. Niez, B. Moulia, J. Dlouha, E. Badel

Abstract:

Trees adjust their development to the environmental conditions they experience. Storms events of last decades showed that acclimation of trees to mechanical stresses due to wind is a very important process that allows the trees to sustain for long years. In the future, trees will experience new wind patterns, namely, more often strong winds and fewer daily moderate winds. Moreover, these patterns will go along with drought periods that may interact with the capacity of trees to adjust their growth to mechanical stresses due to wind. It is necessary to understand the mechanisms of wood functional acclimations to environmental conditions in order to predict their behaviour and in order to give foresters and breeders the relevant tools to adapt their forest management. This work aims to study how trees adjust the mechanical and hydraulic functions of their wood to environmental stresses and how this acclimation may be beneficial for the tree to resist to future stresses. In this work, young poplars were grown under controlled climatic conditions that include permanent environmental stress (daily mechanical stress of the stem by bending and/or hydric stress). Then, the properties of wood formed under these stressed conditions were characterized. First, hydraulic conductivity and sensibility to cavitation were measured at the tissue level in order to evaluate the changes in water transport capacity. Secondly, bending tests and Charpy impact tests were carried out at the millimetric scale to locally measure mechanical parameters such as elastic modulus, elastic limit or rupture energy. These experimental data allow evaluating the impacts of mechanical and water stress on the wood material. At the stem level, they will be merged in an integrative model in order to evaluate the beneficial aspect of wood acclimation for trees.

Keywords: acclimation, environmental stresses, hydraulics, mechanics, wood

Procedia PDF Downloads 198

Authors: Azad Jarrahian, Ehsan Heidaryan

Abstract:

Matrix acidizing treatments can yield impressive production increase if properly applied. In this study, carbonate samples taken from Ahwaz Oilfield have undergone static solubility, sludge, emulsion, and core flooding tests. In each test interaction of acid and rock is reported and at the end it has been shown that how initial permeability and type of acid affects the overall treatment efficiency.

Keywords: carbonate acidizing, organic acids, spending rate, acid penetration, incomplete spending.

Procedia PDF Downloads 424

Authors: J. M. Alzate, J. Baena

Abstract:

This work presents the final results of the ‘Diagnosis of the hydrological and hydrogeological potential in the Mancomojan basin for estimations of offer and demand’ with the purpose of obtaining solutions of domestic supply for the communities of the zone of study. There was realized the projection of population of the paths by three different scenes. The highest water total demand appears with the considerations of the scene 3, with a total demand for the year 2050 of 59.275 m3/year (1,88 l/s), being the path San Francisco the one that exercises a major pressure on the resource with a demand for the same year of the order of 31.189 m3/year (0,99 l/s). As for the hydrogeological potential of the zone and as alternative of supply of the studied communities, the stratigraphic columns obtained of the geophysical polls do not show strata saturated with water that could be considered to be a potential source of supply for the communities. The water registered in the geophysics tests presents very low resistances what indicates that he presents ions, this water meets in the rock interstices very thin granulometries which indicates that it is a water of constitution, and the flow of this one towards more permeable granulometries is void or limited. The underground resource that is registered so much in electrical vertical polls (SEV) as in tomography and that is saturating rocks of thin granulometry (clays and slimes), was demonstrated by content of ions, which is consistent with the abundant presence of plaster and the genesis marinades with transition to continental of the geological units in the zone. Predominant rocks are sedimentary, sandy rocks of grain I die principally, in minor proportion were observed also sandstones of thick grain to conglomerate with clastic rock of quartz, chert and siltstone of the Formation Mess and sandstones (of thin, average and thick grain) alternating with caps conglomerate whose thickness is, in general, between 5 and 15 cm, the nodules of sandstones are frequent with the same composition of the sandstones that contain them, in some cases with calcareous and crossed stratification of the formation Sincelejo Miembro Morroa.

Keywords: hydrological, hydrogeological potential, geotomography, vertical electrical sounding (VES)

Procedia PDF Downloads 251

Authors: Huixin Wei, Shibin Wang, Linan Li, Lei Zhou, Xinhao Tu

Abstract:

Facial skin is a biomedical material with complex mechanical properties of anisotropy, viscoelasticity, and hyperelasticity. The mechanical properties of facial skin are crucial for a number of applications including facial plastic surgery, animation, dermatology, cosmetic industry, and impact biomechanics. Skin is a complex multi-layered material which can be broadly divided into three main layers, the epidermis, the dermis, and the hypodermis. Collagen fibers account for 75% of the dry weight of dermal tissue, and it is these fibers which are responsible for the mechanical properties of skin. Many research on the anisotropic mechanical properties are mainly concentrated on in vitro, but there is a great difference between in vivo and in vitro for mechanical properties of the skin. In this study, we presented a method to measure the mechanical properties of facial skin in vivo. Digital image correlation (DIC) and indentation tests were used to obtain the experiment data, including the deformation of facial surface and indentation force-displacement curve. Then, the experiment was simulated using a finite element (FE) model. Application of Computed Tomography (CT) and reconstruction techniques obtained the real tissue geometry. A three-dimensional FE model of facial skin, including a bi-layer system, was obtained. As the epidermis is relatively thin, the epidermis and dermis were regarded as one layer and below it was hypodermis in this study. The upper layer was modeled as a Gasser-Ogden-Holzapfel (GOH) model to describe hyperelastic and anisotropic behaviors of the dermis. The under layer was modeled as a linear elastic model. In conclusion, the material properties of two-layer were determined by minimizing the error between the FE data and experimental data.

Keywords: facial skin, indentation test, finite element, digital image correlation, computed tomography

Procedia PDF Downloads 103

Authors: Ian A. McCulloh, Madelaine Zinser, Jesse Patsolic, Michael Ramos

Abstract:

Recommender systems are a common artificial intelligence (AI) application. For any given input, a search system will return a rank-ordered list of similar items. As users review returned items, they must decide when to halt the search and either revise search terms or conclude their requirement is novel with no similar items in the database. We present a statistically designed experiment that investigates the impact of similarity ratings on human judgement to conclude a search item is novel and halt the search. 450 participants were recruited from Amazon Mechanical Turk to render judgement across 12 decision tasks. We find the inclusion of ratings increases the human perception that items are novel. Percent similarity increases novelty discernment when compared with star-rated similarity or the absence of a rating. Ratings reduce the time to decide and improve decision confidence. This suggests the inclusion of similarity ratings can aid human decision-makers in knowledge search tasks.

Keywords: ratings, rankings, crowdsourcing, empirical studies, user studies, similarity measures, human-centered computing, novelty in information retrieval

Procedia PDF Downloads 113

Authors: M. Moayeri, A. Kaflou

Abstract:

Decreasing the size of heat exchangers in industries is favorable due to a reduction in the initial costs and maintenance. This can be achieved generally by increasing the heat transfer coefficient, which can be done by increasing tube surface by passive methods named “porous coat”. Since these coatings are often in contact with the fluid, mechanical strength of coatings should be considered as main concept beside permeability and porosity in design, especially in high velocity services. Powder shape affected mechanical property more than other factors. So in this study, the Copper powder with three different shapes (spherical, dendritic and irregular) was coated on Cu-Ni base metal with thickness of ~300µm in a reduction atmosphere (5% H2-N2) and programmable furnace. The morphology and physical properties of coatings, such as porosity, permeability and mechanical strength were investigated. Results show although irregular particle have maximum porosity and permeability but strength level close to spherical powder, in addition, mentioned particle has low production cost, so for creating porous coats in high velocity services these powder recommended.

Keywords: porous coat, permeability, mechanical strength, porosity

Procedia PDF Downloads 349

Authors: W. Thongwat, B. Terakulsatit

Abstract:

The study area is Kham Sakaesaeng District in Nakhon Ratchasima Province, the south section of Northeastern Thailand, located in the Lower Khorat-Ubol Basin. This region is the one of saline soil area, located in a dry plateau and regularly experience standing with periods of floods and alternating with periods of drought. Especially, the drought in the summer season causes the major saline soil and saline water problems of this region. The general cause of dry land salting resulted from salting on irrigated land, and an excess of water leading to the rising water table in the aquifer. The purpose of this study is to determine the relationship of physical and chemical properties between the soil and groundwater. The soil and groundwater samples were collected in both rainy and summer seasons. The content of pH, electrical conductivity (EC), total dissolved solids (TDS), chloride and salinity were investigated. The experimental result of soil and groundwater samples show the slightly pH less than 7, EC (186 to 8,156 us/cm and 960 to 10,712 us/cm), TDS (93 to 3,940 ppm and 480 to 5,356 ppm), chloride content (45.58 to 4,177,015 mg/l and 227.90 to 9,216,736 mg/l), and salinity (0.07 to 4.82 ppt and 0.24 to 14.46 ppt) in the rainy and summer seasons, respectively. The distribution of chloride content and salinity content were interpolated and displayed as a map by using ArcMap 10.3 program, according to the season. The result of saline soil and brined groundwater in the study area were related to the low-lying topography, drought area, and salt-source exposure. Especially, the Rock Salt Member of Maha Sarakham Formation was exposed or lies near the ground surface in this study area. During the rainy season, salt was eroded or weathered from the salt-source rock formation and transported by surface flow or leached into the groundwater. In the dry season, the ground surface is dry enough resulting salt precipitates from the brined surface water or rises from the brined groundwater influencing the increasing content of chloride and salinity in the ground surface and groundwater.

Keywords: environmental geology, soil salinity, geochemistry, groundwater hydrology

Procedia PDF Downloads 113

Authors: Camila Parodi, Viviana Letelier, Giacomo Moriconi

Abstract:

The cement industry is responsible for around a 5% of the CO2 emissions worldwide and considering that concrete is one of the most used materials in construction its total effect is important. An alternative to reduce the environmental impact of concrete production is to incorporate certain amount of residues in the dosing, limiting the replacement percentages to avoid significant losses in the mechanical properties of the final material. Previous researches demonstrate the feasibility of using brick and rust residues, separately, as a cement replacement. This study analyses the variation in the mechanical properties of mortars by incorporating masonry residue composed of clay bricks and cement mortar. In order to improve the mechanical properties of masonry residue, this was subjected to a heat treatment of 650 ° C for four hours and its effect is analyzed in this study. Masonry residue was obtained from a demolition of masonry perimetral walls. The residues were crushed and sieved and the maximum size of particles used was 75 microns. The percentages of cement replaced by masonry residue were 0%, 10%, 20% and 30%. The effect of masonry residue addition and its heat treatment in the mechanical properties of mortars is evaluated through compressive and flexural strength tests after 7, 14 and 28 curing days. Results show that increasing the amount of masonry residue used increases the losses in compressive strength and flexural strength. However, the use of up to a 20% of masonry residue, when a heat treatment is applied, allows obtaining mortars with similar compressive strength to the control mortar. Masonry residues mortars without a heat treatment show losses in compressive strengths between 15% and 27% with respect to masonry residues with heat treatment, which demonstrates the effectiveness of the heat treatment. From this analysis it can be conclude that it is possible to use up to 20% of masonry residue with heat treatment as cement replacement without significant losses in mortars mechanical properties, reducing considerably the environmental impact of the final material.

Keywords: cement replacement, environmental impact, masonry residue, mechanical properties of recycled mortars

Procedia PDF Downloads 374

Authors: Ana Rahma Yuniarti, Ki Moo Lim

Abstract:

Slowed myocardial conduction velocity (CV) and shortened action potential duration (APD) due to some reason are associated with an increased risk of re-entrant excitation, predisposing to cardiac arrhythmia. That is because both of CV reduction and APD shortening induces shortening of wavelength. In this study, we investigated quantitatively the cardiac mechanical responses under various CV and APD using multi-scale computational model of the heart. The model consisted of electrical model coupled with the mechanical contraction model together with a lumped model of the circulatory system. The electrical model consisted of 149.344 numbers of nodes and 183.993 numbers of elements of tetrahedral mesh, whereas the mechanical model consisted of 356 numbers of nodes and 172 numbers of elements of hexahedral mesh with hermite basis. We performed the electrical simulation with two scenarios: 1) by varying the CV values with constant APD and 2) by varying the APD values with constant CV. Then, we compared the electrical and mechanical responses for both scenarios. Our simulation showed that faster CV and longer APD induced largest resultants wavelength and generated better cardiac pumping efficacy by increasing the cardiac output and consuming less energy. This is due to the long wave propagation and faster conduction generated more synchronous contraction of whole ventricle.

Keywords: conduction velocity, action potential duration, mechanical contraction model, circulatory model

Procedia PDF Downloads 195

Authors: Mohamed M. Diab, Koura G. Mohamed, A. Balbaa, Radwan Sh. Ahamed

Abstract:

Background: Chronic mechanical low back pain (CMLBP) is the most common complaint of the working-age population. Mechanical low back pain is often a chronic, dull, aching pain of varying intensity that affects the lower spine. In the current proposal the hip rotation-CMLBP relationship is based on that limited hip motion will be compensated by motion in the lumbopelvic region and this increase force translates to the lumbar spine. The purpose of this study was to investigate if there a relationship between chronic mechanical low back pain (CMLBP) and hip medial and lateral rotation (peak torque and Range of motion (ROM) in patients with CMLBP. Methods: Sixty patients with CMLBP diagnosed by an orthopedist participated in the current study after signing a consent form. Their mean of age was (23.76±2.39) years, mean of weight (71.8±12.7) (Kg), mean of height (169.65±7.49) (Cm) and mean of BMI (25.5±3.86) (Kg/m2). Visual Analogue Scale (VAS) was used to assess pain. Fluid Filled Inclinometer was used to measure Hip rotation ROM (medial and lateral). Isokinetic Dynamometer was used to measure peak torque of hip rotators muscles (medial and lateral), concentric peak torque with tow Isokinetic speeds (60ᵒ/sec and 180ᵒ/sec) was selected to measure peak torque. Results: The results of this study demonstrated that there is poor relationship between pain and hip external rotation ROM, also there is poor relation between pain and hip internal rotation ROM. There is poor relation between pain and hip internal rotators peak torque and hip external rotators peak torque in both speeds. Conclusion: Depending on the current study it is not recommended to give an importance to hip rotation in treating Chronic Mechanical Low Back Pain.

Keywords: hip rotation ROM, hip rotators strength, low back pain, chronic mechanical

Procedia PDF Downloads 298

Authors: E. Manikandan, C. Chilambarasan, M. Sulthan Ariff Rahman, S. Kanagaraj, V. R. Sanal Kumar

Abstract:

The noise regulations around the major airports and rocket launching stations due to the environmental concern have made jet noise a crucial problem in the present day aero-acoustics research. The three main acoustic sources in jet nozzles are aerodynamics noise, noise from craft systems and engine and mechanical noise. Note that the majority of engine noise is due to the jet noise coming out from the exhaust nozzle. The previous studies reveal that the potential of chevron nozzles for aircraft engines noise reduction is promising owing to the fact that the jet noise continues to be the dominant noise component, especially during take-off. In this paper parametric analytical studies have been carried out for optimizing the number of chevron lobes, the lobe length and tip shape, and the level of penetration of the chevrons into the flow over a variety of flow conditions for various aerospace applications. The numerical studies have been carried out using a validated steady 3D density based, SST k-ω turbulence model with enhanced wall functions. In the numerical study, a fully implicit finite volume scheme of the compressible, Navier–Stokes equations is employed. We inferred that the geometry optimization of an environmental friendly chevron nozzle with a suitable number of chevron lobes with aerodynamically efficient tip contours for facilitating silent exit flow will enable a commendable sound reduction without much thrust penalty while comparing with the conventional supersonic nozzles with same area ratio.

Keywords: chevron nozzle, jet acoustic level, jet noise suppression, shape optimization of chevron nozzles

Procedia PDF Downloads 306

Authors: Dolly Selikane, Thandi Gumede

Abstract:

Among the commonly studied organic fillers for polycaprolactone (PCL), cellulose is the most promising. It is available in various particle sizes and sources, providing numerous options for finding a suitable match for PCL matrices. In this study, cellulose was extracted from the leaves of E. autumnalis to create a PCL/nanocellulose composite through melt blending. The prepared nanocellulose was blended with PCL at a weight ratio of 97/3, and the resulting composite was characterized by its thermal and mechanical properties. The results showed that the addition of nanocellulose to PCL improved its mechanical properties, with a maximum increase of 29% in tensile strength and 31% in Young's modulus. The SEM analysis confirmed the successful blending of PCL and nanocellulose. The findings of this study suggest that the nanocellulose from Eucomis autumnalis plant has the potential to improve the mechanical properties of PCL and could be used in biomedical and packaging applications.

Keywords: polycaprolactone, medicinal plants, Eucomis autumnalis, nanocellulose, composite

Procedia PDF Downloads 109

Authors: Cagri Mollamahmutoglu, Ali Mercan, Aykut Levent

Abstract:

Studies concerning the microstructures are becoming more important as the utilization of various micro-electro mechanical systems (MEMS) are increasing. Thus in recent years, thermal buckling and vibration analysis of microstructures have been subject to many investigations that are utilizing different numerical methods. In this study, thermal effects on mechanical response of a functionally graded (FG) Timoshenko micro-beam are presented in the framework of a mixed finite element formulation. Size effects are taken into consideration via modified couple stress theory. The mixed formulation is based on a function which in turn is derived via Gateaux Differential scientifically. After the resolution of all field equations of the beam, a potential operator is carefully constructed. Then this operator is used for the manufacturing of the functional. Usual procedures of finite element approximation are utilized for the derivation of the mixed finite element equations once the potential is obtained. Resulting finite element formulation allows usage of C₀ type simple linear shape functions and avoids shear-locking phenomena, which is a common shortcoming of the displacement-based formulations of moderately thick beams. The developed numerical scheme is used to obtain the effects of thermal loads on the static bending, free vibration and buckling of FG Timoshenko micro-beams for different power-law parameters, aspect ratios and boundary conditions. The versatility of the mixed formulation is presented over other numerical methods such as generalized differential quadrature method (GDQM). Another attractive property of the formulation is that it allows direct calculation of the contribution of micro effects on the overall mechanical response.

Keywords: micro-beam, functionally graded materials, thermal effect, mixed finite element method

Procedia PDF Downloads 126

Authors: Samen Boota, Arslan Ishaq

Abstract:

More than 4 billion tons of chicken feathers are wasted yearly worldwide which is not environmental friendly. In order to make use of these 4 billion tons of feathers it is necessary to incorporate them to the textile materials. The main objective of this study is to develop the winter wears with improved thermal comfort and mechanical properties. Chick feathers were blended with cotton fibers to spin them into yarn, weave them dye them using reactive dyes. The developed fabric was tested for thermal comfort, tensile and tears strength. The results were also compared with pure cotton fabric of similar GSM. It is observed from the results that chicken feathers and cotton blended fabric was improved thermal comfort and mechanical properties.

Keywords: Alambeta, compatibilizing, permeability, sliver

Procedia PDF Downloads 331

Authors: Rio Hirakawa, Christian Gundlach, Sven Hartwig

Abstract:

In recent years, the use of aluminium has further expanded and is expected to replace steel in the future as vehicles become lighter and more recyclable in order to reduce greenhouse gas (GHG) emissions and improve fuel economy. In line with this, structures and components are becoming increasingly multi-material, with different materials, including aluminium, being used in combination to improve mechanical utility and performance. A common method of assembling dissimilar materials is mechanical fastening, but it has several drawbacks, such as increased manufacturing processes and the influence of substrate-specific mechanical properties. Adhesive bonding and fusion bonding are methods that overcome the above disadvantages. In these two joining methods, surface pre-treatment of the substrate is always necessary to ensure the strength and durability of the joint. Previous studies have shown that laser surface treatment improves the strength and durability of the joint. Yan et al. showed that laser surface treatment of aluminium alloys changes α-Al2O3 in the oxide layer to γ-Al2O3. As γ-Al2O3 has a large specific surface area, is very porous and chemically active, laser-treated aluminium surfaces are expected to undergo physico-chemical changes over time and adsorb moisture and organic substances from the air or storage atmosphere. The impurities accumulated on the laser-treated surface may be released at the adhesive and bonding interface by the heat input to the bonding system during the joining phase, affecting the strength and durability of the joint. However, only a few studies have discussed the effect of such storage periods on laser-treated surfaces. This paper, therefore, investigates the ageing of laser-treated aluminium alloy surfaces through thermal analysis, electrochemical analysis and microstructural observations.AlMg3 of 0.5 mm and 1.5 mm thickness was cut using a water-jet cutting machine, cleaned and degreased with isopropanol and surface pre-treated with a pulsed fibre laser at 1060 nm wavelength, 70 W maximum power and 55 kHz repetition frequency. The aluminium surface was then analysed using SEM, thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR) and cyclic voltammetry (CV) after storage in air for various periods ranging from one day to several months TGA and FTIR analysed impurities adsorbed on the aluminium surface, while CV revealed changes in the true electrochemically active surface area. SEM also revealed visual changes on the treated surface. In summary, the changes in the laser-treated aluminium surface with storage time were investigated, and the final results were used to determine the appropriate storage period.

Keywords: laser surface treatment, pre-treatment, adhesion, bonding, corrosion, durability, dissimilar material interface, automotive, aluminium alloys

Procedia PDF Downloads 73

Authors: Olesia Mikhailova, Pavel Rovnaník

Abstract:

In the present work, metakaolin-based geopolymer including different polymer admixtures was studied. Different types of commercial polymer admixtures VINNAPAS^® and polyethylene glycol of different relative molecular weight were used as polymer admixtures. The main objective of this work is to investigate the influence of different types of admixtures on the properties of metakaolin-based geopolymer mortars considering their different dosage. Mechanical properties, such as flexural and compressive strength were experimentally determined. Also, study of the microstructure of selected specimens by using a scanning electron microscope was performed. The results showed that the specimen with addition of 1.5% of VINNAPAS^® 7016 F and 10% of polyethylene glycol 400 achieved maximum mechanical properties.

Keywords: geopolymer, mechanical properties, metakaolin, microstructure, polymer admixtures, porosity

Procedia PDF Downloads 230

Authors: Kamil Dydek, Anna Boczkowska, Paulina Latko-Duralek, Rafal Kozera, Michal Salacinski

Abstract:

In recent years there has been increasing interest in many industries, such as the aviation, automotive, and military industries, in Carbon Fibre Reinforced Polymers (CFRP). This is because of the excellent properties of CFRP, which are characterized by very high strength and stiffness in relation to their mass, low density (almost twice as low as aluminum and more than five times as low as steel), and corrosion resistance. However, they do not have sufficient electrical conductivity, which is required in some applications. Therefore, work is underway to improve their electrical conductivity, for example, by incorporating carbon nanotubes (CNTs) into the CFRP structure. CNTs possess excellent properties, such as high electrical conductivity, high aspect ratio, high Young’s modulus, and high tensile strength. An idea developed by our team is a modification of CFRP by the use of thermoplastic nonwovens containing CNTs. Nanocomposite fibers were made from three different masterbatches differing in the content of multi-wall carbon nanotubes, and then nonwovens that differed in areal weight were produced using a thermo-press. The out of autoclave method was used to fabricate the laminates from commercial carbon-epoxy prepreg dedicated to aviation applications - one without the nonwovens (reference) and five containing nonwovens placed between each prepreg layer. The volume of electrical conductivity of the manufactured laminates was measured in three directions. In order to investigate the adhesion between carbon fibers and nonwovens, the microstructure of the produced laminates was observed. The mechanical properties of the CFRP composites were measured in a short-beam shear test. In addition, the influence of thermoplastic nonwovens on the thermos-mechanical properties of laminates was analyzed by Dynamic Mechanical Analysis. The studies were carried out within grant no. DOB-1-3/1/PS/2014 financed by the National Centre for Research and Development in Poland.

Keywords: CFRP, thermoplastic nonwovens, carbon nanotubes, electrical conductivity

Procedia PDF Downloads 124

Authors: B. A. Mir, Asim Malik

Abstract:

Bottom ash is a by-product of the combustion process of coal in furnaces in the production of electricity in thermal power plants. In India, about 75% of total power is produced by using pulverized coal. The coal of India has a high ash content which leads to the generation of a huge quantity of bottom ash per year posing the dual problem of environmental pollution and difficulty in disposal. This calls for establishing strategies to use this industry by-product effectively and efficiently. However, its large-scale utilization is possible only in geotechnical applications, either alone or with soil. In the present investigation, bottom ash was collected from National Capital Power Station Dadri, Uttar Pradesh, India. Test samples of bottom ash admixed with 20% clayey soil were prepared and treated with different cement content by weight and subjected to various laboratory tests for assessing its suitability as an engineered construction material. This study has shown that use of 10% cement content is a viable chemical additive to enhance the mechanical properties of bottom ash, which can be used effectively as an engineered construction material in various geotechnical applications. More importantly, it offers an interesting potential for making use of an industrial waste to overcome challenges posed by bottom ash for a sustainable environment.

Keywords: bottom ash, environmental pollution, solid waste, sustainable environment, waste utilization

Procedia PDF Downloads 248

Authors: Alessandro Falconieri, Sara De Vincentiis, Vittoria Raffa

Abstract:

Mechanical force regulates axonal growth, elongation and maturation processes. This force is opening new frontiers in the field, contributing to a general understanding of the mechanisms of axon growth that, in the past, was thought to be governed exclusively by the growth cone and its ability to influence axonal growth in response to chemical signals. A method recently developed in our laboratory allows, through the labeling of neurons with magnetic nanoparticles (MNPs) and the use of permanent magnets, to apply extremely low mechanical forces, similar to those generated endogenously by the growth cone or by the increase of body mass during the organism growth. We found that these extremely low forces strongly enhance the spontaneous axonal elongation rate as well as neuronal sprouting. Data obtained don’t exclude that local phenomena, such as local transport and local translation, may be involved. These new advances could shed new light on what happens when the cell is subjected to external mechanical forces, opening new interesting scenarios in the field of mechanobiology.

Keywords: axon, external mechanical forces, magnetic nanoparticles, mechanotransduction

Procedia PDF Downloads 114