Search results for: longitudinal reinforcement

Authors: Richard Abel

Abstract:

In the United States, increased incarceration rates have caused many adolescents to feel the strain of parental absence. This absence is then manifest through adolescent feelings of parental rejection. Additionally, upon reentry maternal incarceration may be related to adolescents experienced perceived excessive disciple. It is possible parents engage in this manner of discipline attempting to prevent the child from taking the same path to incarceration as the parent. According to General Strain Theory, adolescents encountering strain are likely to experience negative emotions. The emotion that is most likely to lead to delinquency is anger through reduced inhibitions and motivation to act. Additionally, males are more likely to engage in delinquent behavior, regardless of experiencing strain. This is not the case for every male who experiences maternal incarceration, parental rejection, excessive discipline, or anger. There are protective factors that enable agency within individuals. One such protective factor is mastery, or the perception that one is in control of his or her own future. The model proposed in this research suggests maternal incarceration is associated with increased parental rejection and excessive discipline in males. Males experiencing parental rejection and excessive discipline are likely to experience increased anger, which is then associated with increases in delinquent behavior. This model explores whether agency, in the form of mastery, mediates the relationship between strains and negative emotions, or between negative emotions and delinquent behavior. The Kaplan Longitudinal and Multigenerational Study (KLAMS) dataset is uniquely situated to analyze this model providing longitudinal data collected from both parents and their offspring. Maternal incarceration is constructed using parental responses such that the mother was incarcerated after the child’s birth, and any incarceration that happened prior to birth is excluded. The remaining variables of the study are all constructed from varying waves of the adolescent survey. Parental rejection, along with control variables for age, race, parental socioeconomic status, neighborhood effects, delinquent peers, and prior delinquent behavior are all constructed using Wave I data. To increase causal inference, the negative emotion of anger and the mediating variable of mastery are measured during Wave II. Lastly, delinquent behavior is measured at Wave III. Results of the analysis show expected relationships such that adolescent males encountering maternal incarceration show increased perception of parental rejection and excessive discipline. Additionally, there is a positive relationship between parental rejection and excessive discipline at Wave I and feelings of anger at Wave II for males. For males experiencing either of these strains in Wave I, feelings of anger in Wave II are found to be associated with increased delinquent behavior in Wave III. Mastery was found to mediate the relationship between both parental rejection and excessive discipline and anger, but no such mediation occurs in the relationship between anger and delinquency, regardless of the strain being experienced. These findings suggest adolescent males who feel they are in control of their own lives are less likely to experience negative emotions produced by the occurrence of strain, thereby decreasing male engagement in delinquent behavior later in life.

Keywords: delinquency, mastery, maternal incarceration, strain

Procedia PDF Downloads 116

Authors: Seyed Mehrdad Gholami

Abstract:

Nowadays, using rail transport system (Metro) is increased in most cities of The world, so the need for safe and economical way of building tunnels and subway stations is felt more and more. One of the most commonly used methods for constructing underground structures in urban areas is NATM (New Austrian tunneling method). In this method, there are some key parameters such as excavation steps and cross-sectional area that have a significant effect on the surface settlement. Settlement is a very important control factor related to safe excavation. In this paper, Finite Element Method is used by Abaqus. R6 station of Tehran Metro Line 6 is built by NATM and the construction of that is studied and analyzed. Considering the outcomes obtained from numerical modeling and comparison with the results of the instrumentation and monitoring of field, finally, the excavation step of 1 meter and longitudinal distance of 14 meters between side drifts is suggested to achieve safe tunneling with allowable settlement.

Keywords: excavation step, NATM, numerical modeling, settlement.

Procedia PDF Downloads 119

Authors: L. Achou, A. Doghmane

Abstract:

Elastic performances, as an essential property of nanowires (NWs), play a significant role in the design and fabrication of modern nanodevices. In this paper, our interest is focused on ZnO NWs to investigate wire diameter (D_wire ≤ 400 nm) effects on elastic properties. The plotted data reveal that a strong size dependence of the elastic constants exists when the wire diameter is smaller than ~ 100 nm. For larger diameters (D_wire > 100 nm), these ones approach their corresponding bulk values. To enrich this study, we make use of the scanning acoustic microscopy simulation technique. The calculation methodology consists of several steps: determination of longitudinal and transverse wave velocities, calculation of refection coefficients, calculation of acoustic signatures and Rayleigh velocity determination. Quantitatively, it was found that changes in ZnO diameters over the ranges 1 nm ≤ D_wire ≤ 100 nm lead to similar exponential variations, for all elastic parameters, of the from: A = a + b exp(-D_wire/c) where a, b, and c are characteristic constants of a given parameter. The developed relation can be used to predict elastic properties of such NW by just knowing its diameter and vice versa.

Keywords: elastic properties, nanowires, semiconductors, theoretical model, ZnO

Procedia PDF Downloads 153

Authors: Gabriela R. Silveira, Claudia S. Rocha, Lais S. Vitti, Jeane L. Borges, Helen B. Durgante

Abstract:

Emerging adulthood occurs after adolescence in a period that maybe be marked by experimentation, identity reconfigurations, labor life demands, and insertion in the work environment, which tends to generate stress and emotional instability. Health promotion programs for the development of strengths and virtues, based on Positive Psychology, for emerging adults are sparse in Brazil. The aim of this study was to evaluate the preliminary effects of an online multi-component Positive Psychology program for the health promotion of emerging adults based on Cognitive Behavioural Therapy and Positive Psychology. The program included six online (synchronous) weekly group sessions of approximately two hours each and homework (asynchronous) activities. The themes worked were Values and self-care/Prudence, Optimism, Empathy, Gratitude, Forgiveness, and Meaning of life and work. This study presents data from a longitudinal, pre-experimental design with pre (T1) and post-test (T2) evaluation in the intervention group. 47 individuals aged between 19-30 years old participated, mean age of 24.53 years (SD=3.13), 37 females (78.7%). 42 (89.4%) self-defined as heterosexual, four (8.5%) as homosexual, and one (2.5%) as bisexual. 33 (70.2%) had incomplete higher education, four (8.5%) completed higher education, and seven (14.9%) had a graduate level of education. 27 participants worked (57.4%), out of which 25 were health workers (53.2%). 14 (29.8%) were caregivers, 27 (57.4%) had a spiritual belief, 36 (76.6%) had access to leisure, and 38 (80.9%) had perceived social support. The instruments used were a sociodemographic questionnaire, the 10-item Perceived Stress Scale, and the 12-item General Health Questionnaire. The program was advertised on social networks and interested participants filled out the Consent Form and the evaluation protocol at T1 and T2 via Google Docs form. The main research was approved (CEP n.1,899,368; 4,143,219; CAAE: 61997516.5.0000.5334) and complied with sanitary and Ethics criteria in research with human beings. Wilcoxon statistics revealed significant improvements in indicators of perceived stress between T1 (X=22.21, SD=6.79) and T2 (X=15.10, SD=5.82); (Z=-4.353; p=0.001) as well as depression and anxiety symptoms (T1:X=26.72, SD=8.84; T2: X=19.23, SD=4.68); (Z=-3.945, p=0.001) of the emerging adults after their participation in the programme. The programme has an innovative character not only for presenting an online Positive Psychology approach but also for being based on an intervention developed, evaluated, and manualized in Brazil. By focusing on emerging adults, this study contributes to advancing research on a relatively new field in developmental studies. As a limitation, this is a pre-experimental and pilot study, requiring an increase in sample size for greater statistical robustness, also qualitative data analysis is crucial for methodological complementarity. The importance of investing efforts to accompany this age group and provide advances in longitudinal research in the area of health promotion and disease prevention is highlighted.

Keywords: emerging adults, disease prevention, health promotion, online program

Procedia PDF Downloads 81

Authors: Taekyun Kim, Jongho Park, Jinwoong Choi, Sun-Kyu Park

Abstract:

Recently, the abnormal climate phenomenon has enlarged due to the global warming. As a result, temperature variation is increasing and the term is being prolonged, frequency of high and low temperature is increasing by heat wave and severe cold. Especially for reinforced concrete structure, the corrosion of reinforcement has occurred by concrete crack due to temperature change and the durability of the structure that has decreased by concrete crack. Accordingly, the textile reinforced concrete (TRC) which does not corrode due to using textile is getting the interest and the investigation of TRC is proceeding. The study of TRC structure behavior has proceeded, but the characteristic study of the concrete used in TRC is insufficient. Therefore, characteristic of the concrete by changing mixing ratio is studied in this paper. As a result, mixing ratio with different water-binder ratio has influenced to the strength of concrete. Also, as the water-binder ratio has decreased, strength of concrete has increased.

Keywords: concrete, mixing ratio, textile, TRC

Procedia PDF Downloads 388

Authors: See-Yuan Cheng, Kwang-Yhee Chin, Shuhaimi Mansor

Abstract:

Rear-roof spoiler is commonly used for improving the aerodynamic performance of road vehicles. This study aims to investigate the effect of yaw angle on the effectiveness of strip-type rear-roof spoiler in providing lower drag and lift coefficients of a hatchback model. A computational fluid dynamics (CFD) method was used. The numerically obtained results were compared to the experimental data for validation of the CFD method. At increasing yaw angle, both the drag and lift coefficients of the model were to increase. In addition, the effectiveness of spoiler was deteriorated. These unfavorable effects were due to the formation of longitudinal vortices around the side edges of the model that had caused the surface pressure of the model to drop. Furthermore, there were significant crossflow structures developed behind the model at larger yaw angle, which were associated with the drop in the surface pressure of the rear section of the model and cause the drag coefficient to rise.

Keywords: Ahmed model, aerodynamics, spoiler, yaw angle

Procedia PDF Downloads 345

Authors: Lotfi Beji, Laredj Benchikh

Abstract:

Underground tunnel face bolting and pipe umbrella reinforcement are one of the most challenging tasks in construction whether industrial or not, and infrastructures such as roads or pipelines. It is one of the first sectors of economic activity in the world. Through a variety of soil and rock, a cyclic Conventional Tunneling Method (CTM) remains the best one for projects with highly variable ground conditions or shapes. CTM is the only alternative for the renovation of existing tunnels and creating emergency exit. During the drilling process, a wide variety of non-desired vibrations may arise, and a method using a robot arm is proposed. The main kinds of drilling through vibration here is the bit-bouncing phenomenon (resonant axial vibration). Hence, assisting the task by a robot arm may play an important role on drilling performances and security. We propose to control the axial-vibration phenomenon along the drillstring at a practical resonant frequency, and embed a Resonant Sonic Drilling Head (RSDH) as a robot end effector for drilling. Many questionable industry drilling criteria and stability are discussed in this paper.

Keywords: drilling, resonant vibration, robot arm, control

Procedia PDF Downloads 272

Authors: Changwon Kwak, Innjoon Park, Dongin Jang

Abstract:

Seismic load affects the behavior of underground structure like tunnel broadly. Seismic soil-structure interaction can play an important role in the dynamic behavior of tunnel. In this research, twin tunnel with flexible joint was physically modeled and the dynamic centrifuge test was performed to investigate seismic behavior of twin tunnel. Seismic waves have different frequency were exerted and the characteristics of response were obtained from the test. Test results demonstrated the amplification of peak acceleration in the longitudinal direction in seismic waves. The effect of the flexible joint was also verified. Additionally, 3-dimensional finite difference dynamic analysis was conducted and the analysis results exhibited good agreement with the test results.

Keywords: 3-dimensional finite difference dynamic analysis, dynamic centrifuge test, flexible joint, seismic soil-structure interaction

Procedia PDF Downloads 239

Authors: Svetlana Nikitenkova, Dmitry Kovriguine

Abstract:

Stationary energy partition between waves in a one dimensional carbyne chain at ambient temperatures is investigated. The study is carried out by standard asymptotic methods of nonlinear dynamics in the framework of classical mechanics, based on a simple mathematical model, taking into account central and noncentral interactions between carbon atoms. Within the first-order nonlinear approximation analysis, triple-mode resonant ensembles of quasi-harmonic waves are revealed. Any resonant triad consists of a single primary high-frequency longitudinal mode and a pair of secondary low-frequency transverse modes of oscillations. In general, the motion of the carbyne chain is described by a superposition of resonant triads of various spectral scales. It is found that the stationary energy distribution is obeyed to the classical Rayleigh–Jeans law, at the expense of the proportional amplitude dispersion, except a shift in the frequency band, upwards the spectrum.

Keywords: resonant triplet, Rayleigh–Jeans law, amplitude dispersion, carbyne

Procedia PDF Downloads 424

Authors: Wenlong Liu, Ru Zhang, Wangjie Li, Shenghui Sang

Abstract:

The boom of smart cities in the age of population aging has caused concerns about the subjective well-being of the elderly. By employing the data from China Health and Retirement Longitudinal Study (CHARLS) 2015, this study uses an ordinary least square to analyze the influence of smart city development on the subjective well-being of the elderly in China. The results of this study suggest that smart cities will improve the life satisfaction of the elderly but reduce their happiness of them. In terms of the moderating effect, social capital negatively moderates the impact of the smart city on the subjective well-being of the elderly. Combined with the results of heterogeneous analysis, it is found that smart city has a stronger impact on the subjective well-being of the elderly with lower levels of personal social capital. To sum up, in the context of the country's vigorous promotion of smart city development, society and families should actively help the elderly to improve their social capital level, enhance the subjective well-being of the elderly, and alleviate the negative effects of smart city development, thereby improving the quality of life of the elderly.

Keywords: the elderly, smart city, social capital, subjective well-being

Procedia PDF Downloads 87

Authors: Souici Abdelaziz, Tehami Mohamed, Rahal Nacer, Said Mohamed Bekkouche, Berthet Jean-Fabien

Abstract:

In this paper, the influence of the concrete slab creep on the initial deformability of a bent composite beam is modelled. This deformability depends on the rate of creep. This means the rise in value of the longitudinal strain ε c(x,t), the displacement D eflec(x,t) and the strain energy E(t). The variation of these three parameters can easily affect negatively the good appearance and the serviceability of the structure. Therefore, an analytical approach is designed to control the status of the deformability of the beam at the instant t. This approach is based on the Boltzmann’s superposition principle and very particularly on the irreversible law of deformation. For this, two conditions of compatibility and two other static equilibrium equations are adopted. The two first conditions are set according to the rheological equation of Dischinger. After having done a mathematical arrangement, we have reached a system of two differential equations whose integration allows to find the mathematical expression of each generalized internal force in terms of the ability of the concrete slab to creep.

Keywords: composite section, concrete, creep, deformation, differential equation, time

Procedia PDF Downloads 366

Authors: Elkedrouci Lotfi, Diao Bo, Pang Sen, Li Yi

Abstract:

Deterioration of reinforced concrete structures is a serious concern in the construction engineering, largely due to chloride induced corrosion of reinforcement. Chloride penetration is markedly influenced by one or several major factors at the same time such as cuing in combination with different crack widths which have spectacular effect on reinforced concrete structures. This research presents the results of an experimental investigation involving reinforced concrete beams with three different crack widths ranging from 0 to 0.2mm, curing temperatures of 20°C or 40°C and water-to-cement of 0.5. Chloride content profiles were determined under non-steady state diffusion at 20°C. Based on the obtained results, higher chloride content was obtained under condition of high curing temperature in combination with large crack more than 0.1mm and there are no significant differences between narrow crack width (less than 0.1 mm) and beams without crack (0mm).

Keywords: crack width, high curing temperature, rapid chloride migration, reinforced concrete beam

Procedia PDF Downloads 187

Authors: Reza Eslami-Farsani, Hamed Khosravi

Abstract:

The aim of this work is to study the influence of multi-walled carbon nanotubes (MWCNTs) addition at various contents with respect to the matrix (0-0.5 wt.% at a step of 0.1 wt.%) on the compressive response of unidirectional basalt fiber (UD-BF)/epoxy composites. Toward this end, MWCNTs were firstly functionalized with 3-glycidoxypropyltrimethoxysilane (3-GPTMS) to improve their dispersion state and interfacial compatibility with the epoxy. Subsequently, UD-BF/epoxy and multiscale 3-GPTMS-MWCNTs/UD-BF/epoxy composites were prepared. The mechanical properties of the composites were determined by quasi-static compression test. The compressive strength of the composites was obtained through performing the compression test on the off-axis specimens and extracting their longitudinal compressive strength. Results demonstrated that the highest value in compressive strength was attained at 0.4 wt.% MWCNTs with 41% increase, compared to the BF/epoxy composite. Potential mechanisms behind these were implied.

Keywords: multiscale polymeric composites, unidirectional basalt fibers, multi-walled carbon nanotubes, surface modification, compressive properties

Procedia PDF Downloads 289

Authors: M. S. Gaafar, S. Y. Marzouk, I. S. Mahmoud, S. Al-Zobaidi

Abstract:

Makishima and Mackenzie model was used to simulation of acoustic properties (longitudinal and shear ultrasonic wave velocities, elastic moduli theoretically for many tellurite and borate glasses. The model was proposed mainly depending on the values of the experimentally measured density, which are obtained before. In this search work, we are trying to obtain the values of densities of amorphous glasses (as the density depends on the geometry of the network structure of these glasses). In addition, the problem of simulating the slope of linear regression between the experimentally determined bulk modulus and the product of packing density and experimental Young's modulus, were solved in this search work. The results showed good agreement between the experimentally measured values of densities and both ultrasonic wave velocities, and those theoretically determined.

Keywords: glasses, ultrasonic wave velocities, elastic modulus, Makishima & Mackenzie Model

Procedia PDF Downloads 367

Authors: Harish Kumar Arya, Kulwant Singh, R. K Saxena, Deepti Jaiswal

Abstract:

The heat flow in weldment changes its nature from 2D to 3D with the increase in plate thickness. For welding of thicker plates the heat loss in thickness direction increases the cooling rate of plate. Since the cooling rate changes, the various bead parameters like bead penetration, bead height and bead width also got affected by it. The present study incorporates the effect of variable plate thickness on bead geometry and dilution. The penetration reduces with increase in plate thickness due to heat loss in thickness direction, while bead width and reinforcement increases for thicker plate due to faster cooling.

Keywords: submerged arc welding, plate thickness, bead geometry, cooling rate

Procedia PDF Downloads 273

Authors: Tejeet Singh, Harmanjit Singh

Abstract:

Creep behavior of thick-walled functionally graded cylinder consisting of AlSiC and subjected to internal pressure and high temperature has been analyzed. The functional relationship between strain rate with stress can be described by the well-known threshold stress based creep law with a stress exponent of five. The effect of imposing non-linear particle gradient on the distribution of creep stresses in the thick-walled functionally graded composite cylinder has been investigated. The study revealed that for the assumed non-linear particle distribution, the radial stress decreases throughout the cylinder, whereas the tangential, axial and effective stresses have averaging effect. The strain rates in the functionally graded composite cylinder could be reduced to significant extent by employing non-linear gradient in the distribution of reinforcement.

Keywords: functionally graded material, pressure, steady state creep, thick-cylinder

Procedia PDF Downloads 460

Authors: P. Pramod Kumar, Madhu Salumari, V. V. Subba Rao

Abstract:

Due to their high strength-to-weight ratio, carbon nanotube (CNTs) reinforced polymer composites are being considered as one of the most promising nanocomposites which can improve the performance when used in structural applications. The buckling behavior is one of the most important parameter needs to be considered in the design of structural members like beams and plates. In the present paper, the elastic constants of CNT reinforced polymer composites are evaluated by using Mori-Tanaka micromechanics approach. Knowing the elastic constants, an analytical study is being conducted to investigate the buckling behavior of nanocomposites for different CNT volume fractions at different boundary conditions using first-order shear deformation theory (FSDT). The effect of stacking sequence and CNT radius on the buckling of beam has also been presented. This study is being conducted primarily with an intension to find the stiffening effect of CNTs when used in polymer composites as reinforcement.

Keywords: CNT, buckling, micromechanics, FSDT

Procedia PDF Downloads 261

Authors: Faten Adel Ismael Chaqmaqchee

Abstract:

Optical, electrical and optical-electrical characterisations of surface light emitting VCSOAs devices are reported. The hot electron light emitting and lasing in semiconductor hetero-structure vertical cavity semiconductor optical amplifier (HELLISH VCSOA) device is a surface emitter based on longitudinal injection of electron and hole pairs in their respective channels. Ga0.35In0.65N0.02As0.08/GaAs was used as an active material for operation in the 1.3 μm window of the optical communications. The device has undoped Distributed Bragg Reflectors (DBRs) and the current is injected longitudinally, directly into the active layers and does not involve DBRs. Therefore, problems associated with refractive index contrast and current injection through the DBR layers, which are common with the doped DBRs in conventional VCSOAs, are avoided. The highest gain of around 4 dB is obtained for the 1300 nm wavelength operation.

Keywords: HELLISH, VCSOA, GaInNAs, luminescence, gain

Procedia PDF Downloads 348

Authors: Lu Zhao, Nadir Farhi, Yeltsin Valero, Zoi Christoforou, Nadia Haddadou

Abstract:

In this paper, a long short-term memory (LSTM) neural network model is proposed to replicate simultaneously car-following and lane-changing behaviors in road networks. By combining two kinds of LSTM layers and three input designs of the neural network, six variants of the LSTM model have been created. These models were trained and tested on the NGSIM 101 dataset, and the results were evaluated in terms of longitudinal speed and lateral position, respectively. Then, we compared the LSTM model with a classical car-following model (the intelligent driving model (IDM)) in the part of speed decision. In addition, the LSTM model is compared with a model using classical neural networks. After the comparison, the LSTM model demonstrates higher accuracy than the physical model IDM in terms of car-following behavior and displays better performance with regard to both car-following and lane-changing behavior compared to the classical neural network model.

Keywords: traffic modeling, neural networks, LSTM, car-following, lane-change

Procedia PDF Downloads 231

Authors: Amit Sharma, J. N. Sharma

Abstract:

This paper deals with the study of reflection and transmission characteristics of acoustic waves at the interface of a semiconductor halfspace and elastic solid. The amplitude ratios (reflection and transmission coefficients) of reflected and transmitted waves to that of incident wave varying with the incident angles have been examined for the case of quasi-longitudinal wave. The special cases of normal and grazing incidence have also been derived with the help of Gauss elimination method. The mathematical model consisting of governing partial differential equations of motion and charge carriers diffusion of n-type semiconductors and elastic solid has been solved both analytically and numerically in the study. The numerical computations of reflection and transmission coefficients has been carried out by using MATLAB programming software for silicon (Si) semiconductor and copper elastic solid. The computer simulated results have been plotted graphically for Si semiconductors. The study may be useful in semiconductors, geology, and seismology in addition to surface acoustic wave (SAW) devices.

Keywords: quasilongitudinal, reflection and transmission, semiconductors, acoustics

Procedia PDF Downloads 376

Authors: Fadwa Jewilli

Abstract:

A sudden leak of a 6-inch gas line pipe after being in service for one year was observed. The pipe had been designed to transport dry gas. The failure had taken place in 6 o’clock position at the stage discharge of the flow process. Laboratory investigations were conducted to find out the cause of the pipe rupture. Visual and metallographic observations confirmed that the pipe split was due to a crack initiated in circumferential and then turned into longitudinal direction. Sever wall thickness reduction was noticed on the internal pipe surface. Scanning electron microscopy observations at the fracture surface revealed features of ductile fracture mode. Corrosion product analysis showed the traces of iron carbonate and iron sulphate. The laboratory analysis resulted in the conclusion that the pipe failed due to the effect of wet fluid (condensate) caused severe wall thickness dissolution resulted in pipe could not stand the continuation at in-service working condition.

Keywords: gas line pipe, corrosion prediction ductile fracture, ductile fracture, failure analysis

Procedia PDF Downloads 69

Authors: Habib Shaban

Abstract:

Nanocomposites of isotactic polypropylene (iPP) and date wood fiber were prepared after modification of the host matrix by reactive extrusion grafting of maleic anhydride. Chemical and mechanical treatment of date wood flour (WF) was conducted to obtain nanocrystalline cellulose. Layered silicates (clay) were partially intercalated with date wood fiber, and the modified layered silicate was used as filler in the PP matrix via a melt-blending process. The tensile strength of composites prepared from wood fiber modified clay was greater than that of the iPP-clay and iPP-WF composites at a 6% filler concentration, whereas deterioration of mechanical properties was observed when clay and WF were used alone for reinforcement. The dispersion of the filler in the matrix significantly decreased after clay modification with cellulose at higher concentrations, as shown by X-ray diffraction (XRD) data.

Keywords: nanocomposites, isotactic polypropylene, date wood flour, intercalated, melt-blending

Procedia PDF Downloads 369

Authors: S. Jahangir, S. H. I. Jaffery, M. Khan, Z. Zareef, A. Yar, A. Mubashir, S. Butt, L. Ali

Abstract:

In this work, drilling responses and behavior of MMC was investigated in Al-Mg2Si composites. For the purpose Al-15% wt. Mg2Si, was selected from the hypereutectic region of Al- Mg2Si phase diagram. Based on hardness and tensile strength, drill bit of appropriate material and morphology was selected. The performance of different drill bits of different morphology and material was studied and analysed using experimental data. For theoretical calculations of axial thrust force and required power calculation, material factor “K” was obtained from different data charts and at the same time cutting forces (drilling forces) were practically obtained using a Peizo electric force dynamometer. These results show the role of reinforcement particles on the machinability of MMCs and provide a useful guide for a better control and optimized drilling parameters for the drilling process. Furthermore, in this work, comparison of MMC with non -reinforced Aluminum Alloy regarding drilling operation was also studied.

Keywords: drilling, metal matrix composite (MMC), cutting forces, thrust force

Procedia PDF Downloads 409

Authors: Rym Zouari, Sami Ben Amar, Abdelwaheb Dogui

Abstract:

This paper presents an experimental characterization of the anisotropic mechanical behavior of 4 textile woven fabrics with different weaves (Twill 3, Plain, Twill4 and Satin 4) by off-axis tensile testing. These tests are applied according seven directions oriented by 15° increment with respect to the warp direction. Fixed and articulated jaws are used. Analysis of experimental results is done through global (Effort/Elongation curves) and local scales. Global anisotropy was studied from the Effort/Elongation curves: shape, breaking load (Frup), tensile elongation (EMT), tensile energy (WT) and linearity index (LT). Local anisotropy was studied from the measurement of strain tensor components in the central area of the specimen as a function of testing orientation and effort: longitudinal strain ɛL, transverse strain ɛT and shearing ɛLT. The effect of used jaws is also analyzed.

Keywords: anisotropy, off-axis tensile test, strain fields, textile woven fabric

Procedia PDF Downloads 342

Authors: H. Nikzad, S. Yoshitomi

Abstract:

This paper presents the design application and reinforcement detailing of 15 storied reinforced concrete shear wall-frame structure based on linear static analysis. Databases are generated for section sizes based on automated structural optimization method utilizing Active-set Algorithm in MATLAB platform. The design constraints of allowable section sizes, capacity criteria and seismic provisions for static loads, combination of gravity and lateral loads are checked and determined based on ASCE 7-10 documents and ACI 318-14 design provision. The result of this study illustrates the efficiency of proposed method, and is expected to provide a useful reference in designing of RC shear wall-frame structures.

Keywords: design constraints, ETABS, linear static analysis, MATLAB, RC shear wall-frame structures, structural optimization

Procedia PDF Downloads 245

Authors: Ehsan Javanmardemamgheisi, Javad Mehr, Jason Ali-Lavroff, Damien Holloway, Michael Davis

Abstract:

During the last decades, a growing interest in faster and more efficient waterborne transportation has led to the development of high-speed vessels for both commercial and military applications. To satisfy this global demand, a wide variety of arrangements of high-speed crafts have been proposed by designers. Among them, high-speed catamarans have proven themselves to be a suitable Roll-on/Roll-off configuration for carrying passengers and cargo due to widely spaced demi hulls, a wide deck zone, and a high ratio of deadweight to displacement. To improve passenger comfort and crew workability and enhance the operability and performance of high-speed catamarans, mitigating the severity of motions and structural loads using Ride Control Systems (RCS) is essential.In this paper, a set of towing tank tests was conducted on a 2.5 m scaled model of a 112 m Incat Tasmania high-speed catamaran in irregular head seas to investigate the effect of different ride control algorithms including linear and nonlinear versions of the heave control, pitch control, and local control on motion responses and passenger comfort of the full-scale ship. The RCS included a centre bow-fitted T-Foil and two transom-mounted stern tabs. All the experiments were conducted at the Australian Maritime College (AMC) towing tank at a model speed of 2.89 m/s (37 knots full scale), a modal period of 1.5 sec (10 sec full scale) and two significant wave heights of 60 mm and 90 mm, representing full-scale wave heights of 2.7 m and 4 m, respectively. Spectral analyses were performed using Welch’s power spectral density method on the vertical motion time records of the catamaran model to calculate heave and pitch Response Amplitude Operators (RAOs). Then, noting that passenger discomfort arises from vertical accelerations and that the vertical accelerations vary at different longitudinal locations within the passenger cabin due to the variations in amplitude and relative phase of the pitch and heave motions, the vertical accelerations were calculated at three longitudinal locations (LCG, T-Foil, and stern tabs). Finally, frequency-weighted Root Mean Square (RMS) vertical accelerations were calculated to estimate Motion Sickness Dose Value (MSDV) of the ship based on ISO 2631-recommendations. It was demonstrated that in small seas, implementing a nonlinear pitch control algorithm reduces the peak pitch motions by 41%, the vertical accelerations at the forward location by 46%, and motion sickness at the forward position by around 20% which provides great potential for further improvement in passenger comfort, crew workability, and operability of high-speed catamarans.

Keywords: high-speed catamarans, ride control system, response amplitude operators, vertical accelerations, motion sickness, irregular waves, towing tank tests.

Procedia PDF Downloads 67

Authors: Shelley Jones

Abstract:

Assumptions abound that education for girls will, as a matter of course, lead to their economic empowerment as women; yet. little is known about the ways in which schooling for girls, who traditionally/historically would not have had opportunities for post-primary, or perhaps even primary education – such as the participants in this study based in rural Uganda - in reality, impacts their economic situations. There is a need forlongitudinal studies in which women share experiences, understandings, and reflections of their lives that can inform our knowledge of this. In response, this paper reports on stage four of a longitudinal case study (2004-2018) focused on education and empowerment for girls and women in rural Uganda, in which 13 of the 15 participants from the original study participated. This paper understands empowerment as not simply increased opportunities (e.g., employment) but also real gains in power, freedoms that enable agentive action, and authentic and viable choices/alternatives that offer ‘exit options’ from unsatisfactory situations. As with the other stages, this study used a critical, postmodernist, global feminist ethnographic methodology, multimodal and qualitative data collection. Participants participated in interviews, focus group discussions, and a two-day workshop, which explored their understandings of how/if they understood post-primary education to have contributed to their economic empowerment. A constructivist grounded theory approach was used for data analysis to capture major themes. Findings indicate that although all participants believe that post-primary education provided them with economic opportunities they would not have had otherwise, the parameters of their economic empowerment were severely constrained by historic and extant sociocultural, economic, political, and institutional structures that continue to disempower girls and women, as well as additional financial responsibilities that they assumed to support others. Even though the participants had post-primary education, and they were able to obtain employment or operate their own businesses that they would not likely have been able to do without post-primary education, the majority of the participants’ incomes were not sufficient to elevate them financially above the extreme poverty level, especially as many were single mothers and the sole income earners in their households. Furthermore, most deemed their working conditions unsatisfactory and their positions precarious; they also experienced sexual harassment and abuse in the labour force. Additionally, employment for the participants resulted in a double work burden: long days at work, surrounded by many hours of domestic work at home (which, even if they had spousal partners, still fell almost exclusively to women). In conclusion, although the participants seem to have experienced some increase in economic empowerment, largely due to skills, knowledge, and qualifications gained at the post-primary level, numerous barriers prevented them from maximizing their capabilities and making significant gains in empowerment. There is need, in addition to providing education (primary, secondary, and tertiary) to girls, to address systemic gender inequalities that mitigate against women’s empowerment, as well as opportunities and freedom for women to come together and demand fair pay, reasonable working conditions, and benefits, freedom from gender-based harassment and assault in the workplace, as well as advocate for equal distribution of domestic work as a cultural change.

Keywords: girls' post-primary education, women's empowerment, uganda, employment

Procedia PDF Downloads 135

Authors: Ruitao Li, Zhili Dong, Nay Win Khun, Khiam Aik Khor

Abstract:

In this study, microstructure and sintering mechanism as well as wear resistance properties of Ti/Al-Cr-Fe metal matrix composites (MMCs) fabricated by spark plasma sintering (SPS) with Ti as matrix and Al-Cr-Fe as reinforcement were investigated. Phases and microstructure of the sintered samples were analyzed using X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and transmission electron microscopy (TEM). Wear resistance properties were tested by ball-on-disk method. An Al3Ti ring forms around each Al-Cr-Fe particle as the bonding layer between Ti and Al-Cr-Fe particles. The Al content in Al-Cr-Fe particles experiences a decrease from 70 at.% to 60 at.% in the sintering process. And these particles consist of quasicrystalline icosahedral AlCrFe and quasicrystal approximants γ-brass Al8(Cr,Fe)5 and Al9(Cr,Fe)4 in the sintered compact. The addition of Al-Cr-Fe particles into the Ti matrix can improve the microhardness by about 40% and the wear resistance is improved by more than 50% due to the increase in the microhardness and the change of wear mechanism.

Keywords: metal matrix composites, spark plasma sintering, phase transformation, wear

Procedia PDF Downloads 405

Authors: LuoJiaoyang, Yu Hongyang

Abstract:

In this paper, we experimented with a new approach to multimodal identification using RGB, RGB-D and voice data. The multimodal combination of RGB and voice data has been applied in tasks such as emotion recognition and has shown good results and stability, and it is also the same in identity recognition tasks. We believe that the data of different modalities can enhance the effect of the model through mutual reinforcement. We try to increase the three modalities on the basis of the dual modalities and try to improve the effectiveness of the network by increasing the number of modalities. We also implemented the single-modal identification system separately, tested the data of these different modalities under clean and noisy conditions, and compared the performance with the multimodal model. In the process of designing the multimodal model, we tried a variety of different fusion strategies and finally chose the fusion method with the best performance. The experimental results show that the performance of the multimodal system is better than that of the single modality, especially in dealing with noise, and the multimodal system can achieve an average improvement of 5%.

Keywords: multimodal, three modalities, RGB-D, identity verification

Procedia PDF Downloads 56

Authors: M. Alsaadi, A. Erkliğ, M. Bulut

Abstract:

This paper experimentally investigates the flexural and tensile properties of the industrial wastes sewage sludge ash (SSA) and fly ash (FA), and conventional ceramic powder silicon carbide (SiC) filled polyester composites. Four weight fractions (5, 10, 15 and 20 wt%) for each micro filler were used for production of composites. Then, test samples were produced according to ASTM. The resulting degree of particle dispersion in the polymer matrix was visualized by using scanning electron microscope (SEM). Results from this study showed that the tensile strength increased up to its maximum value at filler content 5 wt% of SSA, FA and SiC. Flexural strength increased with addition of particulate filler up to its maximum value at filler content 5 wt% of SSA and FA while for SiC decreased for all weight fractions gradually. The addition of SSA, FA and SiC fillers resulted in increase of tensile and flexural modulus for all the particulate composites. Industrial waste SSA can be used as an additive with polymer to produce composite materials.

Keywords: particle-reinforcement, sewage sludge ash, polymer matrix composites, mechanical properties

Procedia PDF Downloads 355