Search results for: crack addiction

Authors: Samir Lecheb, Ahmed Chellil, Hamza Mechakra, Brahim Safi, Houcine Kebir

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In this paper we studied fracture and dynamic behavior of vertical axis wind turbine blade, the VAWT is a historical machine, it has many properties, structure, advantage, component to be able to produce the electricity. We modeled the blade design then imported to Abaqus software for analysis the modes shapes, frequencies, stress, strain, displacement and stress intensity factor SIF, after comparison we chose the idol material. Finally, the CTS test of glass epoxy reinforced polymer plates to obtain the material fracture toughness Kc.

Keywords: blade, crack, frequency, material, SIF

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Authors: Wenhao Li, Shijun Guo

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Carbon fibre reinforced composites are progressively replacing metal structures in modern civil aircraft. This is because composite materials have large potential of weight saving compared with metal. However, the achievement to date of weight saving in composite structure is far less than the theoretical potential due to many uncertainties in structural integrity and safety concern. Unlike the conventional metallic structure, composite components are bonded together along the joints where structural integrity is a major concern. To ensure the safety, metal fasteners are used to reinforce the composite bonded joints. One of the solutions for a significant weight saving of composite structure is to develop an effective technology of on-board Structural Health Monitoring (SHM) System. By monitoring the real-life stress status of composite structures during service, the safety margin set in the structure design can be reduced with confidence. It provides a means of safeguard to minimize the need for programmed inspections and allow for maintenance to be need-driven, rather than usage-driven. The aim of this paper is to develop smart composite joint. The key technology is a multifunctional thermoplastic composite fastener (MTCF). The MTCF will replace some of the existing metallic fasteners in the most concerned locations distributed over the aircraft composite structures to reinforce the joints and form an on-board SHM network system. Each of the MTCFs will work as a unit of the AU and AE technology. The proposed MTCF technology has been patented and developed by Prof. Guo in Cranfield University, UK in the past a few years. The manufactured MTCF has been successfully employed in the composite SLJ (Single-Lap Joint). In terms of the structure integrity, the hybrid SLJ reinforced by MTCF achieves 19.1% improvement in the ultimate failure strength in comparison to the bonded SLJ. By increasing the diameter or rearranging the lay-up sequence of MTCF, the hybrid SLJ reinforced by MTCF is able to achieve the equivalent ultimate strength as that reinforced by titanium fastener. The predicted ultimate strength in simulation is in good agreement with the test results. In terms of the structural health monitoring, a signal from the MTCF was measured well before the load of mechanical failure. This signal provides a warning of initial crack in the joint which could not be detected by the strain gauge until the final failure.

Keywords: composite single-lap joint, crack propagation, multifunctional composite fastener, structural health monitoring

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Authors: Parisa Hasanpour, Bahram Borooghani, Vahid Asadi

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In the current research, a catastrophic failure of a 304 stainless steel flange at pipeline transportation of ethylene in a petrochemical refinery was studied. Cracking was found in the flange after about 78840h service. Through the chemical analysis, tensile tests in addition to microstructural analysis such as optical microscopy and Scanning Electron Microscopy (SEM) on the failed part, it found that the fatigue was responsible for the fracture of the flange, which originated from bumps and depressions on the outer surface and propagated by vibration caused by the working condition.

Keywords: failure analysis, 304 stainless steel, fatigue, flange, petrochemical refinery

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Authors: Carl-Magnus Everitt, Bo Alfredsson

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Contact mechanics and tribology have been combined with fundamental fatigue and fracture mechanics to form the asperity mechanism which supplies an explanation for the surface-initiated rolling contact fatigue damage, called pitting or spalling. The cracks causing the pits initiates at one surface point and thereafter they slowly grow into the material before chipping of a material piece to form the pit. In the current study, the lubrication aspects on fatigue initiation are simulated by passing a single asperity through a thermal elastohydrodynamic lubricated, TEHL, contact. The physics of the lubricant was described with Reynolds equation and the lubricants pressure-viscosity relation was modeled by Roelands equation, formulated to include temperature dependence. A pressure dependent shear limit was incorporated. To capture the full phenomena of the sliding contact the temperature field was resolved through the incorporation of the energy flow. The heat was mainly generated due to shearing of the lubricant and from dry friction where metal contact occurred. The heat was then transported, and conducted, away by the solids and the lubricant. The fatigue damage caused by the asperities was evaluated through Findley’s fatigue criterion. The results show that asperities, in the size of surface roughness found in applications, may cause surface initiated fatigue damage and crack initiation. The simulations also show that the asperities broke through the lubricant in the inlet, causing metal to metal contact with high friction. When the asperities thereafter moved through the contact, the sliding provided the asperities with lubricant releasing the metal contact. The release of metal contact was possible due to the high viscosity the lubricant obtained from the high pressure. The metal contact in the inlet caused higher friction which increased the risk of fatigue damage. Since the metal contact occurred in the inlet it increased the fatigue risk more for asperities subjected to negative slip than positive slip. Therefore the fatigue evaluations showed that the asperities subjected to negative slip yielded higher fatigue stresses than the asperities subjected to positive slip of equal magnitude. This is one explanation for why pitting is more common in the dedendum than the addendum on pinion gear teeth. The simulations produced further validation for the asperity mechanism by showing that asperities cause surface initiated fatigue and crack initiation.

Keywords: fatigue, rolling, sliding, thermal elastohydrodynamic

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Authors: A. Brahma

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Analysis of deferred deformations of concrete under sustained load shows that the creep has a leading role on deferred deformations of concrete structures. Knowledge of the creep characteristics of concrete is a Necessary starting point in the design of structures for crack control. Such knowledge will enable the designer to estimate the probable deformation in pre-stressed concrete or reinforced and the appropriate steps can be taken in design to accommodate this movement. In this study, we propose a prediction model that involves the acting principal parameters on the deferred behaviour of concrete structures. For the estimation of the model parameters Levenberg-Marquardt method has proven very satisfactory. A confrontation between the experimental results and the predictions of models designed shows that it is well suited to describe the evolution of the creep of concrete structures.

Keywords: concrete structure, creep, modelling, prediction

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Authors: Kwangin Kim, Taewon Yoo, Haksoo Han

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Polyimide is a superior polymer in the electronics industry, and we conducted a study to synthesize poly(amide-imide) at low temperatures. Poly(amide-imide) was synthesized at low-temperature curing to offer a thermal stable membrane with low residual stress and good processability. As a result, the low crack polymer with good processability could be used to various applications such as semiconductors, integrated circuits, coating materials, membranes, and display. The synthesis of poly(amide-imide) at low temperatures was confirmed by Fourier transform infrared spectroscopy (FT-IR). Thermal stabilities of the polymer was confirmed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC).

Keywords: poly(amide-imide), residual stress, thermal stability

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Authors: J. Ismail, F. Zaïri, M. Naït-Abdelaziz, Z. Azari

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In this work, a combined approach of continuum damage mechanics (CDM) and fracture mechanics is applied to model a glass plate behavior under static indentation. A spherical indenter is used and a CDM based constitutive model with an anisotropic damage tensor was selected and implemented into a finite element code to study the damage of glass. Various regions with critical damage values were predicted in good agreement with the experimental observations in the literature. In these regions, the directions of crack propagation, including both cracks initiating on the surface as well as in the bulk, were predicted using the strain energy density factor.

Keywords: finite element modeling, continuum damage mechanics, indentation, cracks

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Authors: Reza Hedayati, Meysam Jahanbakhshi

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Fracture Mechanics is used to predict debonding propagation in adhesive joint between aluminum and composite plates. Three types of loadings and two types of glass-epoxy composite sequences: [0/90]2s and [0/45/-45/90]s are considered for the composite plate and their results are compared. It was seen that generally the cases with stacking sequence of [0/45/-45/90]s have much shorter lives than cases with [0/90]2s. It was also seen that in cases with λ=0 the ends of the debonding front propagates forward more than its middle, while in cases with λ=0.5 or λ=1 it is vice versa. Moreover, regardless of value of λ, the difference between the debonding propagations of the ends and the middle of the debonding front is very close in cases λ=0.5 and λ=1. Another main conclusion was the non-dimensionalized debonding front profile is almost independent of sequence type or the applied load value.

Keywords: fatigue, debonding, Paris law, APDL, adhesive

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Authors: A. Chellil, A. Nour, S. Lecheb , H. Mechakra, A. Bouderba, H. Kebir

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The study of the rotor dynamic in transient system allowed to determine the vibratory responses due to various excitations. This work presents a coupled gyroscopic effect in the defects of a rotor under dynamic loading. Calculations of different energies and virtual work from the various elements of the rotor are developed. To treat real systems a model of finite element was developed. This model of the rotor makes it possible to extract the frequencies and modal deformed, and to calculate the stresses in the critical zone. The study of the rotor in transient system allowed to determine the vibratory responses due to the unbalances, crack and various excitations.

Keywords: rotor, defect, finite element, numerical

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Authors: Hannachi Med Tahar, H. Djebaili, B. Daheche

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In this approach, we have tried to describe the flattening of welded tubes, and its experimental application. The test is carried out at the (National product processing company dishes and tubes production). Usually, the final products (tubes) undergo a series of non-destructive inspection online and offline welding, and obviously destructive mechanical testing (bending, flattening, flaring, etc.). For this and for the purpose of implementing the flattening test, which applies to the processing of round tubes in other forms, it took four sections of welded tubes draft (before stretching hot) and welded tubes finished (after drawing hot and annealing), it was also noted the report 'health' flattened tubes must not show or crack or tear. The test is considered poor if it reveals a lack of ductility of the metal.

Keywords: flattening, destructive testing, tube drafts, finished tube, Castem 2001

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Authors: Sue S. Feldman, Bradley Tipper, Benjamin Schooley

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Nearly every community in the US has been impacted by opioid related addictions/deaths; it is a national problem that is threatening our social and economic welfare. Most believe that tackling this problem from a prevention perspective advances can be made toward breaking the chain of addiction. One mechanism, community based participatory research, involves the community in the prevention approach. This project combines that approach with a design science approach to develop an integrated solution. Findings suggested accountable care communities, transpersonal psychology, and social exchange theory as product kernel theories. Evaluation was conducted on a prototype.

Keywords: substance use and abuse recovery, community resource centers, accountable care communities, community based participatory research

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Authors: Akinyemi Olufunminiyi Akinbobola

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This paper analytically discusses the disciplinary problems among Adeyemi College of Education Students in the Ondo State of Nigeria. The paper posits that the causes and types of disciplinary problems experienced by the students are determinacy of disciplinary measures to be taken. The study used a questionnaire titled: Disciplinary Problem Questionnaire (DPQ) to collect data. Five hundred (500) students were randomly sampled in the five schools in the college. The results showed that drug addiction, school curriculum, cultism, peer group influence, overcrowded classroom, political, social, and economic among others are disciplinary problems experienced in the study area. The study made recommendations on how to improve the situation.

Keywords: challenges in higher institutions, disciplinary problems, social vices, students’ indiscipline

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Authors: Maha Hamoud Alatawi

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Drawing on the work of John McLeod and Ariel Watson, this paper explains the relationship between narrative and psychotherapy in two plays by the Irish playwright Conor McPherson. Dublin Carol presents John’s chequered past through his reminiscences of alcohol addiction and Shining City tells the story of John who is haunted by the ghost of his wife, recently died in a car accident, and who seeks the help of Ian, a therapist. At first, the significance of storytelling as an integral part of Irish culture is highlighted. Such a tradition features prominently in contemporary Irish drama. The paper concludes that it is the power of narrative and its therapeutic impact and not the act of psychotherapy and treatment which brings signs of change to characters’ lives.

Keywords: Conor McPherson, drama, psychotherapy, storytelling

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Authors: Nancy Wilson

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In utero, fetal drug exposure is prevalent amongst birthing facilities. Assessment tools for neonatal abstinence syndrome (NAS) are often cumbersome and ill-fitting, harboring immense subjectivity. This paradox often leads the clinical assessor to be hypervigilant when assessing the newborn for subtle symptoms of NAS, often mistaken for normal newborn behaviors. As a quality improvement initiative, this project led to a more adaptable NAS tool termed eat, sleep, console (ESC). This function-based NAS assessment scores the infant based on the ability to accomplish three basic newborn necessities- to sleep, to eat, and to be consoled. Literature supports that ESC methodology improves patient and family outcomes while providing more cost-effective care.

Keywords: neonatal abstinence syndrome, neonatal opioid withdrawal, maternal substance abuse, pregnancy, and addiction, Finnegan neonatal abstinence syndrome tool, eat, sleep, console

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Authors: A. El Amri, M. El Yakhloufi Haddou, A. Khamlichi

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The numerical simulation based on the Finite Element Method (FEM) is widely used in academic institutes and in the industry. It is a useful tool to predict many phenomena present in the classical manufacturing forming processes such as fracture. But, the results of such numerical model depend strongly on the parameters of the constitutive behavior model. The influences of thermal and mechanical loads cause damage. The temperature and strain rate dependent materials’ properties and their modelling are discussed. A Johnson-Cook Model of damage has been selected for the numerical simulations. Virtual software called the ABAQUS 6.11 is used for finite element analysis. This model was introduced in order to give information concerning crack initiation during thermal and mechanical loads.

Keywords: thermo-mechanical fatigue, failure, numerical simulation, fracture, damage

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Authors: Rajesh Bansal, Amit Raj Sharma, Vakil Singh

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The success and predictability of titanium implants for long durations are well established and there has been a tremendous increase in the popularity of implants among patients as well as clinicians over the last four decades. However, sometimes complications arise, which lead to the loss of the implant as well as the prosthesis. Fracture of dental implants is rare; however, at times, implants or abutment screws fracture and lead to many problems for the clinician and the patient. Possible causes of implant fracture include improper design, overload, fatigue and corrosion. Six retrieved fractured dental implants, with varying diameters and designs, were collected from time to time to examine by scanning electron microscope (SEM) to characterize fracture behavior and assess the mechanism of fracture. In this investigation, it was observed that fracture of the five dental implants occurred due to fatigue crack initiation and propagation from the thread roots.

Keywords: titanium, dental, implant, fracture, failure

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Authors: Cheyenne Johnson, Samantha Robinson, Christina Chant, Ann M. Mitchell, Carol Price, Carmel Clancy, Adam Searby, Deborah S. Finnell

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Introduction: Substance use along the continuum from at-risk use to a substance use disorder (SUD) contributes substantially to the burden of disease and related harms worldwide. There is a growing body of literature that highlights the lack of substance use related content in nursing curricula. Furthermore, there is also a lack of consensus on key competencies necessary for entry-level nurses. Globally, there is a lack of established nursing competencies related to prevention, health promotion, harm reduction and treatment of at-risk substance use and SUDs. At a critical time in public health, this gap in nursing curricula contributes to a lack of preparation for entry-level nurses to support people along the continuum of substance use. Thus, in practice, early opportunities for screening, support, and interventions may be missed. To address this gap, an international committee was convened to develop international entry-level nursing competencies specifying the knowledge, skills, and abilities that all nurses should possess in order to address the continuum of substance use. Methodology: An international steering committee, including representation from Canada, United States, United Kingdom, and Australia was established to lead this work over a one-year time period. The steering committee conducted a scoping review, undertaken to examine nursing competency frameworks, and to inform a competency structure that would guide this work. The next steps were to outline key competency areas and establish leaders for working groups to develop the competencies. In addition, a larger international committee was gathered to contribute to competency working groups, review the collective work and concur on the final document. Findings: A comprehensive framework was developed with competencies covering a wide spectrum of substance use across the lifespan and in the context of prevention, health promotion, harm reduction and treatment, including special populations. The development of this competency-based framework meets an identified need to provide guidance for universities, health authorities, policy makers, nursing regulators and other organizations that provide and support nursing education which focuses on care for patients and families with at-risk substance use and SUDs. Conclusion: Utilizing these global competencies as expected outcomes of an educational and skill building curricula for entry-level nurses holds great promise for incorporating evidence-informed training in the care and management of people across the continuum of substance use.

Keywords: addiction nursing, addiction nursing curriculum, competencies, substance use

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Authors: Lounes Aouane, Omar Bouledroua

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Sonatrach uses 24,000 kilometers of pipelines to transport gas and oil. Over time, these pipes run the risk of bursting due to corrosion inside and/or outside the pipeline. For this reason, a check must be made with the help of an equipped scraper. This intelligent tool provides a detailed picture of all errors in the pipeline. Based on the ERF values, these wear defects are divided into two parts: acceptable defect and unacceptable defect. The objective of this work is to conduct a comparative study of the different methods of calculating the marginal pressure found in the literature (DNV RP F-101, SHELL, P-CORRC, NETTO and CSA Z662). This comparison will be made from a database of 329 burst tests published in the literature. Finally, we will propose a new approach based on the finite element method using the commercial software ANSYS.

Keywords: hydrogen embrittlement, pipelines, hydrogen, transient flow, cyclic pressure, fatigue crack growth

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Authors: Abdurahim Abogdera, Omar Hamza, David Elliott

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The soil bacteria can be affected by some factors such as pH, calcium ions and Electrical conductivity. Fresh concrete has high pH value, which is between 11 and 13 and these values will be prevented the bacteria to produce CO₂ to participate with Calcium ions that released from the concrete to get calcite. In this study we replaced 15% and 25% of cement with Fly ash as the fly ash reduce the value of the pH at the concrete. The main goal of this study was investigated whether bacteria can be used on the soil rather than in the concrete to avoid the challenges and limitations of containing bacteria inside the concrete. This was achieved by incubating cracked cement mortar specimens into fully saturated sterilized and non-sterilized soil. The crack sealing developed in the specimens during the incubation period in both soil conditions were evaluated and compared. Visual inspection, water absorption test, scanning electron microscopy (SEM), and Energy Dispersive X-ray (EDX) were conducted to evaluate the healing process.

Keywords: pH, calcium ions, MICP, salinity

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Authors: Quervin Zacary M. Roldan, Gwyneth Gabrielle M. Fajardo, Carmela M. Maciar

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Alcohol in the Philippines is regarded as a part of their culture however, it is also stigmatized, as alcohol addiction is prevalent among Filipino Males leading them to develop Alcohol Use Disorder. With this, Discourses of alcohol consumption from Individuals recovering from AUD from different rehabilitation centers in the Philippines were analyzed in the study to explore how they ‘talk’ about their alcohol consumption. By utilizing the Foucauldian Discourse Analysis following the six steps by Carla Willig, four (4) major discourses were major construed by the recovering individuals of AUD which are: (1) Being alcohol-free was a dream, (2) Drinking alcohol turns you into a demon that will destroy your life, (3) Drinking alcohol as ‘doing’ drugs and (4) Alcohol is a temporary solution. These discourses construct alcohol consumption as something that is being referred to as a 'bad' substance which is both normalized and stigmatized in Philippine society.

Keywords: alcohol, alcohol consumption, alcohol-based beverages, psychological effects, discourse, alcohol use disorder, stigma

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Authors: Rishabh Shukla, Achin Agrawal, Anupam Saxena, S. Mandal

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The existence of a crack, affects the mechanical behaviour and various properties of a structure to a great degree. This paper focuses on recognizing the parameters that gets changed due to the formation of cracks and have a great impact on the performance of the structure. Spalling is a major concern as it leaves the reinforcement bars more susceptible to environmental attacks. Beams of cross section 300 mm × 500 mm are designed and for a calculated area of steel, two different arrangements of reinforced bars are analysed. Results are prepared for different stages of cracking for each arrangement of rebars. The parameters for both arrangements are then compared. The Finite Element Analysis (FEA) is carried out and changes in the properties like flexural strength, Elasticity and modal frequency are reported. The conclusions have been drawn by comparing the results.

Keywords: cracks, elasticity, spalling, FEA

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Authors: Vitalijs Lusis, Andrejs Krasnikovs

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Fiber reinforced concrete is important material for load bearing structural elements. Usually fibers are homogeneously distributed in a concrete body having arbitrary spatial orientations. At the same time, in many situations, fiber concrete with oriented fibers is more optimal. Is obvious, that is possible to create constructions with oriented short fibers in them, in different ways. Present research is devoted to one of such approaches- fiber reinforced concrete prisms having dimensions 100 mm×100 mm×400 mm with layers of non-homogeneously distributed fibers inside them were fabricated. Simultaneously prisms with homogeneously dispersed fibers were produced for reference as well. Prisms were tested under four point bending conditions. During the tests vertical deflection at the center of every prism and crack opening were measured (using linear displacements transducers in real timescale). Prediction results were discussed.

Keywords: fiber reinforced concrete, 4-point bending, steel fiber, construction engineering

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Authors: F. Louati, H. Trabelsi, M. Jamei

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Desiccation cracks following drainage-humidification cycles. With water loss, mainly due to evaporation, suction in the soil increases, producing volumetric shrinkage and tensile stress. When the tensile stress reaches tensile strength, the soil cracks. Desiccation cracks networks can directly control soil hydraulic properties. The aim of this study was for quantifying the hydraulic properties for examples the water retention curve, the saturated hydraulic conductivity, the unsaturated hydraulic conductivity function, the shrinkage dynamics in Tibar soil- clay soil in the Northern of Tunisia. Then a numerical simulation of unsaturated hydraulic properties for a crack network has been attempted. The finite elements code ‘CODE_BRIGHT’ can be used to follow the hydraulic distribution in cracked porous media.

Keywords: desiccation, cracks, permeability, unsaturated hydraulic flow, simulation

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Authors: Firooz Bakhtiari-Nejad, Hamidreza Rostami, Meysam Mirzaee, Mona Zandbaf

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Dynamic tests are an important step of the design of engineering structures, because the accuracy of predictions of theoretical–numerical procedures can be assessed. In experimental test of moving loads that is one of the major research topics, the load is modeled as a simple moving mass or a small vehicle. This paper deals with the applicability of Non-Contact Moving Load (NML) for vibration analysis. For this purpose, an experimental set-up is designed to generate the different types of NML including constant and harmonic. The proposed method relies on pressurized air which is useful, especially when dealing with fragile or sensitive structures. To demonstrate the performance of this system, the set-up is employed for a modal analysis of a beam and detecting crack of the beam. The obtained results indicate that the experimental set-up for NML can be an attractive alternative to the moving load problems.

Keywords: experimental analysis, moving load, non-contact excitation, materials engineering

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Authors: Gyu-Jin Kim, Hyo-Gyoung Kwak

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In this research, the effect of prestressing force on the nonlinearity of concrete was investigated by an experimental study. For the measurement of ultrasonic nonlinearity, a prestressed concrete beam was prepared and a nonlinear resonant ultrasound method was adopted. When the prestressing force changes, the stress state of the concrete inside the beam is affected, which leads to the occurrence of micro-cracks and changes in mechanical properties. Therefore, it is necessary to introduce nonlinear ultrasonic technology which sensitively reflects microstructural changes. Repetitive prestressing load history, including maximum levels of 45%, 60% and 75%, depending on the compressive strength, is designed to evaluate the impact of loading levels on the nonlinearity. With the experimental results, the possibility of ultrasonic nonlinearity as a trial indicator of stress was evaluated.

Keywords: micro crack, nonlinear ultrasonic resonant spectroscopy, prestressed concrete beam, prestressing force, ultrasonic nonlinearity

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Authors: Cailyn Green

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This research investigated the lack of standardization that exists in the field of polysubstance use. This standardization has to do with a uniform way of defining when and if polysubstance is taking place. This research is important to the field of substance abuse as it makes future researchers aware of this lack of uniformity in a commonly used word in the field. By investigating, we make researchers aware of these discrepancies to encourage a uniform definition to be created and used. The methodology for this research was a literary review. This literature review consisted of four peer-reviewed and published journal articles in four different journals. These articles focused on adolescents and their polysubstance use. The research question asked what time frame was used to determine if a client's substance use can be classified as polysubstance use when they reported using two or more substances. The results identify that there is no uniform working definition of the time frame for polysubstance to take place.

Keywords: addiction, adolescence, literary review, polysubstance

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Authors: O. Hassoon, M. Tarfoui, A. El Malk

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Fiber Bragg optic sensor embedded in composite material to detect and monitor the damage which is occur in composite structure. In this paper we deal with the mode-Ι delamination to determine the resistance of material to crack propagation, and use the coupling mode theory and T-matrix method to simulating the FBGs spectrum for both uniform and non-uniform strain distribution. The double cantilever beam test which is modeling in FEM to determine the Longitudinal strain, there are two models which are used, the first is the global half model, and the second the sub-model to represent the FBGs with refine mesh. This method can simulate the damage in the composite structure and converting the strain to wavelength shifting of the FBG spectrum.

Keywords: fiber bragg grating, delamination detection, DCB, FBG spectrum, structure health monitoring

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Authors: Elena B. Cherepetskaya, Vladimir A. Makarov, Dmitry V. Morozov, Ivan E. Sas

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Laboratory studies of the stress-strain behavior of rocks specimens were conducted by using acoustic emission and laser-ultrasonic diagnostics. The sensitivity of the techniques allowed changes in the internal structure of the specimens under uniaxial compressive load to be examined at micro- and macro scales. It was shown that microcracks appear in geologic materials when the stress level reaches about 50% of breaking strength. Also, the characteristic stress of the main crack formation was registered in the process of single-stage compression of rocks. On the base of laser-ultrasonic echoscopy, 2D visualization of the internal structure of rocky soil specimens was realized, and the microcracks arising during uniaxial compression were registered.

Keywords: acoustic emission, geomaterial, laser ultrasound, uniaxial compression

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Authors: João Pedro Zanella, Michel J. O. Fagundes

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Introduction: Drug use has been practised by humans universally for millennia, not excluding any population from these habits, however, the rampant drug use is a global concern due to the harm that affects the health of the world population. In this sense, it is observed the reduction of lasting and effective public policies for the resolution, increasing the demand for treatment services. With this comes ibogaine, an alkaloid derived from the root of an African bush (Tabernanthe Iboga), found mostly in Gabon and used widely by the native Bwiti population in rituals, and also other social groups, which demonstrates efficacy against chemical dependence, psychic and emotional disorders, opioid withdrawal was first confirmed by a study in rats done by Michailo Dzoljic and associates in 1988 and again in 1994. Methods: A brief description of the plant, its neurohumoral potential and the effects caused by ingested doses, in a simplified and objective way, will be discussed in the course of this abstract. Results: Ibogaine is not registered or passed by Anvisa, regarding safety and efficacy, and cannot be sold in Brazil. Its illegal trade reaches R$ 5 thousand for a session with the proceeds of the root, and its effect can last up to 72 hours, attributing Iboga's psychoactive effects to the alkaloid called ibogaine. The shrub where Ibogaine is located has pink and yellow flowers, and its fruit produced does not have psychoactive substances, but its root bark contains 6 to 7% indolic alkaloids. Besides extraction from the iboga plant, ibogaine hydrochloride can be semisynthesized from voacangine, another plant alkaloid that acts as a precursor. Its potential has the ability to perform multiple interactions with the neurotransmitter system, which are closely associated with addiction, including nicotinic, opioid and serotoninergic systems. Studies carried out by Edwards found that the doses administered of Iboga should be determined by a health professional when its purpose is to treat individuals for dependence on other drugs. Its use in small doses may cause an increase in sensibility, impaired vision and motor alterations; in moderate quantities, hallucinations, motor and neurological alterations and impaired vision; in high quantities it may cause hallucinations with personal events at a deeper level lasting up to 24 hours or more, followed by motor and visual alterations. Conclusion: The product extracted from the Iboga plant is of great importance in controlling addiction, reducing the need for the use of narcotics by patients, thus gaining a space of extreme importance in the treatment of users of psychoactive substances. It is remarkable the progress of the latest’s research about the usefulness of Ibogaine, and its benefits for certain treatments, even with the restriction of its sale in Brazil. Besides this, Ibogaine has an additional benefit of helping the patient to gain self-control over their destructive behaviours.

Keywords: alkaloids, dependence, Gabon, ibogaine

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Authors: Weigao. Wu, Stefano. Utili

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Based on the kinematic approach of limit analysis, a full set of upper bound solutions for the stability of homogeneous rock slopes subjected to tension cracks are obtained. The generalized Hoek-Brown failure criterion is employed to describe the non-linear strength envelope of rocks. In this paper, critical failure mechanisms are determined for cracks of known depth but unspecified location, cracks of known location but unknown depth, and cracks of unspecified location and depth. It is shown that there is a nearly up to 50% drop in terms of the stability factors for the rock slopes intersected by a tension crack compared with intact ones. Tables and charts of solutions in dimensionless forms are presented for ease of use by practitioners.

Keywords: Hoek-Brown failure criterion, limit analysis, rock slope, tension cracks

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