Search results for: structural break

Authors: Mohsen Tehranizadeh, Mahboobe Forghani

Abstract:

The impact of higher modes on the seismic response of dual structural system consist of concrete moment-resisting frame and with RC shear walls is investigated against near-field earthquakes in this paper. a 20 stories reinforced concrete shear wall-special moment frame structure is designed in accordance with ASCE7 requirements and The nonlinear model of the structure was performed on OpenSees platform. Nonlinear time history dynamic analysis with 3 near-field records are performed on them. In order to further understand the structural collapse behavior in the near field, the response of the structure at the moment of collapse especially the formation of plastic hinges is explored. The results revealed that the amplification of moment at top of the wall due to higher modes, the plastic hinge can form in the upper part of wall, even when designed and detailed for plastic hinging at the base only (according to ACI code).on the other hand, shear forces in excess of capacity design values can develop due to the contribution of the higher modes of vibration to dynamic response due to the near field can cause brittle shear or sliding failure modes. The past investigation on shear walls clearly shows the dual-hinge design concept is effective at reducing the effects of the second mode of response. An advantage of the concept is that, when combined with capacity design, it can result in relaxation of special reinforcing detailing in large portions of the wall. In this study, to investigate the implications of multi-design approach, 4 models with varies arrangement of hinge plastics at the base and height of the shear wall are considered. results base on time history analysis showed that the dual or multi plastic hinges approach can be useful in order to control the high moment and shear demand of higher mode effect.

Keywords: higher mode effect, Near-field earthquake, nonlinear time history analysis, multi plastic hinge design

Procedia PDF Downloads 431

Authors: Adinarayana S., Sudhakar I.

Abstract:

Energy conversion is one of the inevitable parts of any industries. It involves either conversion of mechanical energy in to electrical or vice versa. The later conversion of energy i.e. electrical to mechanical emphasizes the need of motor. Statistics reveals, about 8 % of industries’ annual turnover met on maintenance. Thus substantial numbers of efforts are required to minimize in incurring expenditure met towards break down maintenance. Condition monitoring is one of such techniques based on vibration widely used to recognize premature failures and paves a way to minimize cumbersome involved during breakdown of machinery. The present investigation involves a case study of squirrel cage induction motor (frequently in the electro machines) has been chosen for the conditional monitoring to predict its soundness on the basis of results of FFT analyser. Accelerometer which measures the acceleration converts in to impulses by FFT analyser generates vibration spectrum and time spectrum has been located at various positions on motor under different conditions. Results obtained from the FFT analyser are compared to that of ISO standard vibration severity charts are taken to predict the preventative condition of considered machinery. Initial inspection of motor revealed that stator faults, broken end rings in rotor, eccentricity faults and misalignment between bearings are trouble shootings areas for present investigation. From the results of the shaft frequencies, it can be perceived that there is a misalignment between the bearings at both the ends. The higher order harmonics of FTF shows the presence of cracks on the race of the bearings at both the ends which are in the incipient stage. Replacement of the bearings at both the drive end (6306) and non drive end (6206) and the alignment check between the bearings in the shaft are suggested as the constructive measures towards preventive maintenance of considered squirrel cage induction motor.

Keywords: FFT analyser, condition monitoring, vibration spectrum, time wave form

Procedia PDF Downloads 389

Authors: Chengfeng Fang, Mohamed Ali Sadakkathulla, Abdul Sheikh

Abstract:

Ultra-high-performance fiber reinforced concrete (UHPFRC) is a specially formulated cement-based composite characterized with an ultra-high compressive strength (f_c^’ = 240 MPa) and a low water-cement ratio (W/B= 0.2). With such material characteristics, UHPFRC is favored for the design and constructions of structures required high structural performance and slender geometries. Unlike conventional concrete, the structural performance of members manufactured with UHPFRC has not yet been fully studied, particularly, for UHPFRC columns with high slenderness. In this study, the behaviors of slender UHPFRC columns under concentric or eccentric load will be investigated both experimentally and numerically. Four slender UHPFRC columns were tested under eccentric loads with eccentricities, of 0 mm, 35 mm, 50 mm, and 85 mm, respectively, and one UHPFRC beam was tested under four-point bending. Finite element (FE) analysis was conducted with concrete damage plasticity (CDP) modulus to simulating the load-middle height or middle span deflection relationships and damage patterns of all UHPFRC members. Simulated results were compared against the experimental results and observation to gain the confidence of FE model, and this model was further extended to conduct parametric studies, which aim to investigate the effects of slenderness regarding failure modes and load-moment interaction relationships. Experimental results showed that the load bearing capacities of the slender columns reduced with an increase in eccentricity. Comparisons between load-middle height and middle span deflection relationships as well as damage patterns of all UHPFRC members obtained both experimentally and numerically demonstrated high accuracy of the FE simulations. Based on the available FE model, the following parametric study indicated that a further increase in the slenderness of column resulted in significant decreases in the load-bearing capacities, ductility index, and flexural bending capacities.

Keywords: eccentric loads, ductility index, RC column, slenderness, UHPFRC

Procedia PDF Downloads 132

Authors: Suneeta Gireesh Panicker

Abstract:

Aim: Aminopeptidase P (APP) is an enzyme that has specificity for proline, can specifically cleave Xaa-Proline peptides and is a metallo-aminopeptidase. The bonds nearby to the imino acid proline are tough to cleave by many peptidases, but APP can specifically break peptide bonds engaged with proline. Membrane-bound form and a cytosolic form are the two forms in which this enzyme exists. The exact physiological function of APP remains unclear and hence the present work attempts to determine it. Methods: In the present study, the expression pattern of cytosolic Aminopeptidase P (DAP) was determined in all the embryonic stages and larval stages of wild-type Drosophila by using polyclonal monospecific antibodies. To show the presence of DAP RNA in embryonic and larval stages, RNA in situ hybridization was performed. DAP promoter-LacZ fusion reporter gene vector was used to construct transgenic embryos to study the regulation pattern of DAP. To study the DAP expression profile, a transgenic fly consisting of a DAP promoter with β-gal and GFP reporter genes in front of it was constructed. Results: DAP protein expression was observed in neuroectodermal cells, posterior midgut primordium, proctodeum, ventral neuroblast and primordial stomatogastric nervous system. It was observed in the ventral cord and midgut in stage 12. The completely developed embryos showed the intense occurrence of it in the ventral cord and gut region. The eye-antennal disc, wing disc and leg disc also showed the presence of DAP protein. LacZ expression in transgenic embryos also showed the same pattern. Conclusion: Similar to various known multiple-functional proteins, DAP could be one with different functions at different stages and in different cells. Data presented here designates DAP functions in the early embryonic and imaginal dics differentiation and development, suggesting that it may be required for the metabolism of proteins like neuropeptides and tachykinins.

Keywords: aminopeptidase P, in situ hybridization, transgenic fly, embryonic stages

Procedia PDF Downloads 87

Authors: Aura Maria Lopera Echavarria, Angela Maria Lema Perez, Daniela Medrano David, Pedronel Araque Marin, Marta Elena Londoño Lopez

Abstract:

Bone regeneration is the process by which the formation of new bone is stimulated. Bone fractures can originate at any time due to trauma, infections, tumors, congenital malformations or skeletal diseases. Currently there are different strategies to treat bone defects that in some cases, regeneration does not occur on its own. That is why they are treated with bone substitutes, which provide a necessary environment for the cells to synthesize new bone. The Demineralized Bone Matrix (DBM) is widely used as a bone implant due to its good properties, such as osteoinduction and bioactivity. However, the use of DBM is limited, because its presentation is powder, which is difficult to implant with precision and is susceptible to migrating to other sites through blood flow. That is why the DBM is commonly incorporated into a variety of vehicles or carriers. The objective of this project is to evaluate the bioactive and confinement properties of a bone substitute based on demineralized bone matrix (DBM). Also, structural and morphological properties were evaluated. Bone substitute was obtained from EIA Biomaterials Laboratory of EIA University and the DBM was facilitated by Tissue Bank Foundation. Morphological and structural properties were evaluated by scanning electron microscopy (SEM), X-ray diffraction (DRX) and Fourier transform infrared spectroscopy with total attenuated reflection (FTIR-ATR). Water absorption capacity and degradation were also evaluated during three months. The cytotoxicity was evaluated by the MTT test. The bioactivity of the bone substitute was evaluated through immersion of the samples in simulated body fluid during four weeks. Confinement tests were performed on tibial fragments of a human donor with bone defects of determined size, to ensure that the substitute remains in the defect despite the continuous flow of fluid. According of the knowledge of the authors, the methodology for evaluating samples in a confined environment has not been evaluated before in real human bones. The morphology of the samples showed irregular surface and presented some porosity. DRX confirmed a semi-crystalline structure. The FTIR-ATR determined the organic and inorganic phase of the sample. The degradation and absorption measurements stablished a loss of 3% and 150% in one month respectively. The MTT showed that the system is not cytotoxic. Apatite clusters formed from the first week were visualized by SEM and confirmed by EDS. These calcium phosphates are necessary to stimulate bone regeneration and thanks to the porosity of the developed material, osteinduction and osteoconduction are possible. The results of the in vitro evaluation of the confinement of the material showed that the migration of the bone filling to other sites is negligible, although the samples were subjected to the passage of simulated body fluid. The bone substitute, putty type, showed stability, is bioactive, non-cytotoxic and has handling properties for specialists at the time of implantation. The obtained system allows to maintain the osteoinductive properties of DBM and it can fill completely fractures in any way; however, it does not provide a structural support, that is, it should only be used to treat fractures without requiring a mechanical load.

Keywords: bone regeneration, cytotoxicity, demineralized bone matrix, hydrogel

Procedia PDF Downloads 122

Authors: Fiffy Hanisdah Saikim, Bruce Prideaux

Abstract:

One of the aims of wildlife tourism is to educate visitors about the threats facing wildlife, in general, and the actions needed to protect the environment and maintain biodiversity. Annually, millions of tourists visit natural areas and zoos primarily to view flagship species such as rhinos and elephants. Venues rely on the inherent charisma of these species to increase visitation and anchor conservation efforts. Expected visitor outcomes from the use of flagships include raised levels of awareness and pro-conservation behaviors. However, the role of flagships in wildlife tourism has been criticized for not delivering conservation benefits for species of interest or biodiversity and producing negative site impacts. Furthermore, little is known about how the connection to a species influences conservation behaviors. This paper addresses this gap in knowledge by extending previous work exploring wildlife tourism to include the emotional connection formed with wildlife species and pro-conservation behaviors for individual species and biodiversity. This paper represents a substantial contribution to the field because (a) it incorporates the role of the experience in understanding how tourists connect with a species and how this connection influences pro-conservation behaviors; and (b) is the first attempt to operationalize Conservation Caring as a measure of tourists’ connection with a species. Existing studies have investigated how specific elements, such as interpretation or species’ morphology may influence programmatic goals or awareness. However, awareness is a poor measure of an emotional connection with an animal. Furthermore, there has not been work done to address the holistic nature of the wildlife viewing experience, and its subsequent influence on behaviors. Results based on the structural equation modelling, support the validity of Conservation Caring as a factor; the ability of wildlife tourism to influence Conservation Caring; and that this connection is a strong predictor of conservation awareness behaviors. These findings suggest wildlife tourism can deliver conservation outcomes. The studies in this paper also provide a valuable framework for structuring wildlife tourism experiences to align with flagship related conservation outcomes, and exploring a wider assemblage of species as potential flagships.

Keywords: wildlife tourism, conservation caring, conservation awareness, structural equation modelling

Procedia PDF Downloads 293

Authors: Pratiwi Retnaningdyah, Sofie Dewayani

Abstract:

Foreign domestic workers are arguably one of the most exploited and subordinated groups of women in the labor division under global capitalism. However, foreign domestic workers (FDWs) actively engage in activities to negotiate the prevailing structures of power in the transnational labor market. This paper seeks to understand the significance of Indonesian Domestic Workers (IDWs) cultural representations in relation to the themes of literacy and space. In particular, this paper addresses the issue of how IDWs in Hong Kong make use of the practice of suitcase libraries to make meaning of space within material limits. The term ‘suitcase libraries’ is used to refer to a literacy practice of book borrowing at outdoor public spaces in Hong Kong during IDWs’ days off. The books are displayed in open suitcases and mats, with IDWs both as administrators and consumers engaged in the practice. This paper argues that suitcase libraries can be considered representing Thirdspace in the form of a vernacular, grassroots literacy practice that creates a productive space of resistance and community empowerment. Employing participant observation and a textual analysis of IDWs’ literacy narratives, the study traced IDWs’ literacy trajectories to the period of IDWs’ permanent return to Indonesia. Through extended engagement in community literacy practices in their hometowns, former IDWs develop their literacy capital and break the stereotypes of uneducated and passive maids and change them into literate figures. In the context of literacy movement that has gained momentum in Indonesia recently, the practice of IDWs’ suitcase libraries is also useful as a reference point to further investigate how community literacy sponsors in Indonesia also create Thirdspace and develop literacy capital through community libraries (TBM, Taman Baca Masyarakat).

Keywords: identity, Indonesian domestic workers, literacy narratives, Thirdspace

Procedia PDF Downloads 179

Authors: M. Ibrir, S. Berri, S. Lakel, D. Maouche And Y. Medkour

Abstract:

We have performed first-principle calculations of the structural, electronic and magnetic properties of KFeF3, KCoF3, KMnF3, KVF3, using full-potential linearized augmented plane-wave (FP-LAPW) scheme within GGA. Features such as the lattice constant, bulk modulus and its pressure derivative are reported. Also, we have presented our results of the band structure and the density of states. The magnetic moments of KFeF3, KCoF3, KMnF3, KVF3 compounds are in most came from the exchange-splitting of X-3d orbital.

Keywords: Ab initio calculations, electronic structure, magnetic materials

Procedia PDF Downloads 421

Authors: Defne Uz

Abstract:

Horizontal Tail of helicopter is exposed to repeated oscillatory loading generated by aerodynamic and inertial loads, and bending moments depending on operating conditions and maneuvers of the helicopter. In order to ensure that maximum stress levels do not exceed certain fatigue limit of the material and to prevent damage, a numerical analysis approach can be utilized through the Finite Element Method. Therefore, in this paper, fatigue analysis of the Horizontal Tail model is studied numerically to predict high-cycle and low-cycle fatigue life related to defined loading. The analysis estimates the stress field at stress concentration regions such as around fastener holes where the maximum principal stresses are considered for each load case. Critical element identification of the main load carrying structural components of the model with rivet holes is performed as a post-process since critical regions with high-stress values are used as an input for fatigue life calculation. Once the maximum stress is obtained at the critical element and the related mean and alternating components, it is compared with the endurance limit by applying Soderberg approach. The constant life straight line provides the limit for several combinations of mean and alternating stresses. The life calculation based on S-N (Stress-Number of Cycles) curve is also applied with fully reversed loading to determine the number of cycles corresponds to the oscillatory stress with zero means. The results determine the appropriateness of the design of the model for its fatigue strength and the number of cycles that the model can withstand for the calculated stress. The effect of correctly determining the critical rivet holes is investigated by analyzing stresses at different structural parts in the model. In the case of low life prediction, alternative design solutions are developed, and flight hours can be estimated for the fatigue safe operation of the model.

Keywords: fatigue analysis, finite element method, helicopter horizontal tail, life prediction, stress concentration

Procedia PDF Downloads 148

Authors: Adi Narayana S Sudhakar. I

Abstract:

Energy conversion is one of the inevitable parts of any industries. It involves either conversion of mechanical energy in to electrical or vice versa. The later conversion of energy i.e. electrical to mechanical emphasizes the need of motor .Statistics reveals, about 8 % of industries’ annual turnover met on maintenance. Thus substantial numbers of efforts are required to minimize in incurring expenditure met towards break down maintenance. Condition monitoring is one of such techniques based on vibration widely used to recognize premature failures and paves a way to minimize cumbersome involved during breakdown of machinery. The present investigation involves a case study of squirrel cage induction motor (frequently in the electro machines) has been chosen for the conditional monitoring to predict its soundness on the basis of results of FFT analyser. Accelerometer which measures the acceleration converts in to impulses by FFT analyser generates vibration spectrum and time spectrum has been located at various positions on motor under different conditions. Results obtained from the FFT analyzer are compared to that of ISO standard vibration severity charts are taken to predict the preventative condition of considered machinery. Initial inspection of motor revealed that stator faults, broken end rings in rotor, eccentricity faults and misalignment between bearings are trouble shootings areas for present investigation. From the results of the shaft frequencies, it can be perceived that there is a misalignment between the bearings at both the ends. The higher order harmonics of FTF shows the presence of cracks on the race of the bearings at both the ends which are in the incipient stage. Replacement of the bearings at both the drive end (6306) and non-drive end (6206) and the alignment check between the bearings in the shaft are suggested as the constructive measures towards preventive maintenance of considered squirrel cage induction motor.

Keywords: FFT analyser, condition monitoring, vibration spectrum, time spectrum accelerometer

Procedia PDF Downloads 452

Authors: A. Abbasi Moshaii, M. Soltan Rezaee, M. Mohammadi Moghaddam

Abstract:

Control of some mechanisms is hard because of their complex dynamic equations. If part of the complexity is resulting from uncertainties, an efficient way for solving that is robust control. By this way, the control procedure could be simple and fast and finally, a simple controller can be designed. One kind of these mechanisms is 3-RRR which is a parallel mechanism and has three revolute joints. This paper aims to robust control a 3-RRR planner mechanism and it presents that this could be used for other mechanisms. So, a significant problem in mechanisms control could be solved. The relevant diagrams are drawn and they show the correctness of control process.

Keywords: 3-RRR, dynamic equations, mechanisms control, structural uncertainty

Procedia PDF Downloads 558

Authors: Mohammed Mainoma, Abubakar Tijanni, Mohammed Aliyu

Abstract:

Globalization has brought a structural change in industry. It is the breaking of artificial boundaries and given way to new product, new service, new market, and new technology among others. It leads to the realization that men entrepreneurs’ alone cannot meet the demand of the teeming population. Therefore there is a need for the participation, involvement, and engagement of females in the production and distribution of goods and services. This will enhance growth and development of a nation. It is in line with the above that this paper attempt to discuss meaning of women entrepreneurs, roles, types, problems, and prospects. Also, on the basis of conclusion the paper recommended that entrepreneurship education should be introduced in all Tertiary Institutions in Nigeria.

Keywords: women, entrepreneurs, issues, challenges

Procedia PDF Downloads 518

Authors: Khue Do Phan

Abstract:

Nike has been confronted by the press with their harsh working conditions, underpayment and highly-labor intensive requirement to their manufacturing workers and hiring of underage workers in Vietnam, Nike's largest production center. To analyze this topic critically through an international relations perspective, theory of dependency will be used to criticize the notion of exploitation of resources from developed countries towards developing countries. Theory of economic liberalism will be used to support the notion private property, the free market and generally capitalism as beneficial to both developing and developed countries. Workers are mentally, physically and sexually abused in the factories. In addition to this, their working conditions consist of improper training, lack of safety equipment, exposure of chemicals (glues and pants), their average wage is below the minimum wage in their country; the workers have to work around 60 hours or more a week. Even Nike says that the conditions are regulated often to make sure the workers get a voice to have their work rights and safe working environment. The monitors come to analyze the factories but in the end talk to the employers, whom are the direct abusers to the employees. Health benefits are rarely granted to the employees; they are forced to pay their bills first then the company will reimburse them later. They would also get in trouble for using the bathroom, taking a lunch break or sick days off because this would mean it would decrease their hours of work, leading to an even lower wage and a really angry employer. Of course with the press criticizing Nike’s lack of respect for human rights and working rights, Nike has been working on policy making and implementation to deal with the abuses. Due to its large chains and a great number of outsourcing host countries, the changes that Nike wish or attempt to make have not be in effect as quickly nor spreading to all countries it holds accountable for in its outsourcing factories.

Keywords: dependency theory, economic liberalism, human rights, outsource

Procedia PDF Downloads 336

Authors: Peter Krupa, Svetozár Malinarič

Abstract:

Transient plane source method has been used to measure the thermal diffusivity and thermal conductivity of a compact isostatic electro-ceramics at room temperature. The samples were fired at temperatures from 100 up to 1320 degrees Celsius in steps of 50. Bulk density and specific heat capacity were also measured with their corresponding standard uncertainties. The results were compared with further thermal analysis (dilatometry and thermogravimetry). Structural processes during firing were discussed.

Keywords: TPS method, thermal conductivity, thermal diffusivity, thermal analysis, electro-ceramics, firing

Procedia PDF Downloads 492

Authors: Hsiao-ting Lin

Abstract:

This paper analyzes the history of Taiwan’s secret program to develop its nuclear weapons during the Cold War. In July 1971, US President Richard Nixon shocked the world when he announced that his national security adviser Henry Kissinger had made a secret trip to China and that he himself had accepted an invitation to travel to Beijing. This huge breakthrough in the US-PRC relationship was followed by Taipei’s loss of political legitimacy and international credibility as a result of its UN debacle in the fall that year. Confronted with the Nixon White House’s opening to the PRC, leaders in Taiwan felt being betrayed and abandoned, and they were obliged to take countermeasures for the sake of national interest and regime survival. Taipei’s endeavor to create an effective nuclear program, including the possible development of nuclear weapons capabilities, fully demonstrates the government’s resolution to pursue its own national policy, even if such a policy was guaranteed to undermine its relations with the United States. With hindsight, Taiwan’s attempt to develop its own nuclear weapons did not succeed in sabotaging the warming of US-PRC relations. Worse, it was forced to come to a full stop when, in early 1988, the US government pressured Taipei to close related facilities and programs on the island. However, Taiwan’s abortive attempt to develop its nuclear capability did influence Washington’s and Beijing’s handling of their new relationship. There did develop recognition of a common American and PRC interest in avoiding a nuclearized Taiwan. From this perspective, Beijing’s interests would best be served by allowing the island to remain under loose and relatively benign American influence. As for the top leaders on Taiwan, such a policy choice demonstrated how they perceived the shifting dynamics of international politics in the 1960s and 1970s and how they struggled to break free and pursue their own independent national policy within the rigid framework of the US-Taiwan alliance during the Cold War.

Keywords: taiwan, richard nixon, nuclear program, chiang Kai-shek, chiang ching-kuo

Procedia PDF Downloads 134

Authors: Musa Alghamdi

Abstract:

Although Saudi students’ motivation to learn English language as a foreign language in Saudi Arabia have been investigated by a number of studies; these have appeared almost completely as using the quantitative research paradigm. There is a significant lack of research that explores the Saudi students’ motivation using qualitative methods. It was essential, as an investigator, to be immersed in the community to understand the individuals under study via their actions and words, their thoughts, views and beliefs, and how those individuals credited to activities. Thus, the study aims to explore the Saudi students’ motivation to learn English language as a foreign language in Saudi Arabia employing qualitative methodology via applying ethnography. The study will be carried out in Saudi Arabia. Ethnography qualitative approach will be used in the current study by employing formal and informal interview instruments. Gardner’s motivation theory is used as frameworks for this study to aid the understanding of the research findings. The author, an English language lecturer, will undertake participant observations for 4 months. He will work as teaching-assistant (on an unpaid basis) with EFL lecturers in different discipline department at a Saudi university where students study English language as a minor course. The researcher will start with informal ethnographical interview with students during his existence with the informants in their natural context. Then the researcher will utilize the semi-structural interview. The informal interview will be with 14-16 students, then, he will carry out semi-structural interview with the same informants to go deep in their natural context to find out to what extent the Saudi university students are motivated to learn English as a foreign language. As well as, to find out the reasons that played roles in that. The findings of this study will add new knowledge about what factors motivate universities’ Saudi students to learn English language in Saudi Arabia. Very few chances have given to students to express themselves and to speak about their feelings in a more comfortable way in order to gain a clear image of those factors. The working author as an EFL teacher and lecturer will provide him secure access into EFL teaching and learning setting. It will help him attain richer insights into the nature EFL context in universities what will provide him with richer insights into the reasons behind the weakness of EFL level among Saudi students.

Keywords: motivation, ethnography, Saudi, language

Procedia PDF Downloads 298

Authors: Nastaran Cheshmehkaboodi, Lotfi Guizani, Noureddine Ghlamallah

Abstract:

Seismic isolation proves to be a powerful technology in reducing seismic hazards and enhancing overall structural resilience. However, the performance of the technology can be influenced by various factors, including seismic inputs and soil conditions. This research aims to investigate the effects of moderate and strong earthquakes associated with different distances of the source on the seismic responses of conventional and isolated bridges, considering the soil-structure interaction effects. Two groups of moderate and strong near-fault records are applied to the conventional and isolated bridges, with and without considering the underlying soil. For this purpose, using the direct method, three soil properties representing rock, dense, and stiff soils are modeled in Abaqus software. Nonlinear time history analysis is carried out, and structural responses in terms of maximum deck acceleration, deck displacement, and isolation system displacement are studied. The comparison of dynamic responses between both earthquake groups demonstrates a consistent pattern, indicating that the bridge performance and the effects of soil-structure interaction are primarily influenced by the ground motions and their frequency contents. Low ratios of PGA/PGV are found to significantly impact all dynamic responses, resulting in higher force and displacement responses, regardless of the distance associated with the ruptured fault. In addition, displacement responses increase drastically on softer soils. Thus, meticulous consideration is crucial in designing isolation systems to avoid underestimating displacement demands and to ensure sufficient displacement capacity. Despite a lower PGA value in high seismicity areas in this study, the acceleration demand during strong earthquakes is up to 1.3 times higher in conventional bridges and up to 3 times higher in isolated bridges than in moderate earthquakes. Additionally, the displacement demand in strong earthquakes is up to 2 times higher in conventional bridges and up to 5 times higher in isolated bridges compared to moderate earthquakes, highlighting the increased force and displacement demand in strong earthquakes.

Keywords: bridges, seismic isolation, near-fault, earthquake characteristics, soil-structure interaction

Procedia PDF Downloads 63

Authors: P. Serrão, E. Costa, A. Ribeiro, V. Infante

Abstract:

The characteristic sonority of the Portuguese guitar is in great part what makes Fado so distinguishable from other traditional song styles. The Portuguese guitar is a pear-shaped plucked chordophone with six courses of double strings. This study compares the two types of plain strings available for Portuguese guitar and used by the musicians. One is stainless steel spring wire, the other is high carbon spring steel (music wire). Some musicians mention noticeable differences in sound quality between these two string materials, such as a little more brightness and sustain in the steel strings. Experimental tests were performed to characterize string tension at pitch; mechanical strength and tuning stability using the universal testing machine; dimensional control and chemical composition analysis using the scanning electron microscope. The string dynamical behaviour characterization experiments, including frequency response, inharmonicity, transient response, damping phenomena and were made in a monochord test set-up designed and built in-house. Damping factor was determined for the fundamental frequency. As musicians are able to detect very small damping differences, an accurate a characterization of the damping phenomena for all harmonics was necessary. With that purpose, another improved monochord was set and a new system identification methodology applied. Due to the complexity of this task several adjustments were necessary until obtaining good experimental data. In a few cases, dynamical tests were repeated to detect any evolution in damping parameters after break-in period when according to players experience a new string sounds gradually less dull until reaching the typically brilliant timbre. Finally, each set of strings was played on one guitar by a distinguished player and recorded. The recordings which include individual notes, scales, chords and a study piece, will be analysed to potentially characterize timbre variations.

Keywords: damping factor, music wire, portuguese guitar, string dynamics

Procedia PDF Downloads 553

Authors: Preeti Verma, P. Chellapandi, N.C. Santhi Srinivas, Vakil Singh

Abstract:

Modified 9Cr-1Mo steel is widely used for structural components like heat exchangers, pressure vessels and steam generator in the nuclear reactors. It is also found to be a candidate material for future metallic fuel sodium cooled fast breeder reactor because of its high thermal conductivity, lower thermal expansion coefficient, micro structural stability, high irradiation void swelling resistance and higher resistance to stress corrosion cracking in water-steam systems compared to austenitic stainless steels. The components of steam generators that operate at elevated temperatures are often subjected to repeated thermal stresses as a result of temperature gradients which occur on heating and cooling during start-ups and shutdowns or during variations in operating conditions of a reactor. These transient thermal stresses give rise to LCF damage. In the present investigation strain controlled low cycle fatigue tests were conducted at room temperature and 300 °C in normalized and tempered condition using total strain amplitudes in the range from ±0.25% to ±0.5% at strain rate of 10-2 s-1. Cyclic Stress response at high strain amplitudes (±0.31% to ±0.5%) showed initial softening followed by hardening upto a few cycles and subsequent softening till failure. The extent of softening increased with increase in strain amplitude and temperature. Depends on the strain amplitude of the test the stress strain hysteresis loops displayed Masing behaviour at higher strain amplitudes and non-Masing at lower strain amplitudes at both the temperatures. It is quite opposite to the usual Masing and Non-Masing behaviour reported earlier for different materials. Low cycle fatigue damage was evaluated in terms of plastic strain and plastic strain energy approach at room temperature and 300 °C. It was observed that the plastic strain energy approach was found to be more closely matches with the experimental fatigue lives particularly, at 300 °C where dynamic strain aging was observed.

Keywords: Modified 9Cr-mo steel, low cycle fatigue, Masing behavior, cyclic softening

Procedia PDF Downloads 445

Authors: Vernie C. Convicto, Henry P. Aringa, Wilson I. Barredo

Abstract:

This study presents a conformational model of the helical structures of globular protein particularly ferritin in the framework of white noise path integral formulation by using Associated Legendre functions, Bessel and convolution of Bessel and trigonometric functions as modulating functions. The model incorporates chirality features of proteins and their helix-turn-helix sequence structural motif.

Keywords: globular protein, modulating function, white noise, winding probability

Procedia PDF Downloads 478

Authors: H. Pasternak, A. Chwastek

Abstract:

The paper describes the results from a research project about repair of welds. The repair was carried out by grinding the flawed seams and re-welding them. The main task was to determine the FAT classes of original state and after repair of seams according to the assessment procedures, such as nominal, structural and effective notch stress approach. The first part shows the results of the tests, the second part encloses numerical analysis and evaluation of results to determine the fatigue strength classes according to three assessment procedures.

Keywords: cyclic loading, fatigue crack, post-weld treatment, seams’ repair

Procedia PDF Downloads 260

Authors: Chen Chuanzhi, Guo Yunyun

Abstract:

The large linear array feeding parabolic cylindrical antenna of the satellite has the ability of large-area line focusing, multi-directional beam clusters simultaneously in a certain azimuth plane and elevation plane, corresponding quickly to different orientations and different directions in a wide frequency range, dual aiming of frequency and direction, and combining space power. Therefore, the large-diameter parabolic cylindrical antenna has become one of the new development directions of spaceborne antennas. Limited by the size of the rocked fairing, the large-diameter spaceborne antenna is required to be small mass and have a deployment function. After being orbited, the antenna can be deployed by expanding and be stabilized. However, few types of structures can be used to construct large cylindrical shell structures in existing structures, which greatly limits the development and application of such antennas. Aiming at high structural efficiency, the geometrical characteristics of parabolic cylinders and mechanism topological mapping law to the expandable truss are studied, and the basic configuration of deployable truss with cylindrical shell is structured. Then a modular truss parabolic cylindrical antenna is designed in this paper. The antenna has the characteristics of stable structure, high precision of reflecting surface formation, controllable motion process, high storage rate, and lightweight, etc. On the basis of the overall configuration comprehensive theory and optimization method, the structural stiffness of the modular truss parabolic cylindrical antenna is improved. And the bearing density and impact resistance of support structure are improved based on the internal tension optimal distribution method of reflector forming. Finally, a truss-type cylindrical deployable support structure with high constriction-deployment ratio, high stiffness, controllable deployment, and low mass is successfully developed, laying the foundation for the application of large-diameter parabolic cylindrical antennas in satellite antennas.

Keywords: linear array feed antenna, truss type, parabolic cylindrical antenna, spaceborne antenna

Procedia PDF Downloads 160

Authors: Suddhasil Siddhanta, Debasish Nandy

Abstract:

Child sex ratios pattern in the Asian Population is highly masculine mainly due to birth masculinity and gender bias in child mortality. The vast and the growing literature of female deficit in world population points out the diffusion of child sex ratio pattern in many Asian as well as neighboring European countries. However, little attention has been given to understand the common factors in different demographics in explaining child sex ratio pattern. Such a scholarship is extremely important as level of gender inequity is different in different country set up. Our paper tries to explain the major structural commonalities in the child masculinity pattern in two demographic billionaires - India and China. The analysis reveals that apart from geographical diffusion of sex selection technology, patrilocal social structure, as proxied by households with more than one generation in China and proportion of population aged 65 years and above in India, can explain significant variation of missing girl child in these two countries. Even after controlling for individual capacity building factors like educational attainment, or work force participation, the measure of social stratification is coming out to be the major determinant of child sex ratio variation. Other socio economic factors that perform much well are the agency building factors of the females, like changing pattern of marriage customs which is proxied by divorce and remarriage ratio for china and percentage of female marrying at or after the age of 20 years in India and the female workforce participation. Proportion of minorities in socio-religious composition of the population and gender bias in scholastic attainment in both these counties are also found to be significant in modeling child sex ratio variations. All these significant common factors associated with child sex ratio point toward the one single most important factor: the historical evolution of patriarchy and its contemporary perpetuation in both the countries. It seems that prohibition of sex selection might not be sufficient to combat the peculiar skewness of excessive maleness in child population in both these countries. Demand sided policies is therefore utmost important to root out the gender bias in child sex ratios.

Keywords: child sex ratios, gender bias, structural factors, prosperity, patrilocality

Procedia PDF Downloads 157

Authors: Nikica Mihaljević

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Published in 2023, "Tre ciotole. Rituali per un anno di crisi" is a collection of short stories completely disconnected from one another in regard to topics and the representation of characters. However, these short stories complete and somehow continue each other in a particular way. The book happens to be Murgia's last book, as the author died a few months later after the book's publication and it appears as a kind of summary of all her previous literary works. Namely, in her previous publications, Murgia already stressed certain characters' particularities, such as solitude and alienation from others, which are at the center of attention in this literary work, too. What all the stories present in "Tre ciotole" have in common is the dealing with characters' identity and self-awareness through the challenges they confront and the way the characters live their emotions in relation to the surrounding space. Although the challenges seem similar, the spatial element around the characters is different, but it confirms each time that characters' emotions, and, consequently, their self-awareness, can be formed and built only through their connection and relation to the surrounding space. In that way, the reader creates an imaginary network of complex relations among characters in all the short stories, which gives him/her the opportunity to search for a way to break out of the usual patterns that tend to be repeated while characters focus on building self-awareness. The aim of the paper is to determine and analyze the role of spatial elements in the creation of characters' emotions and in the process of self-awareness. As the spatial element changes or gets transformed and/or substituted, in the same way, we notice the arise of the unconscious desire for self-harm in the characters, which damages their self-awareness. Namely, the characters face a crisis that they cannot control by inventing other types of crises that can be controlled. That happens to be their way of acting in order to find the way out of the identity crisis. Consequently, we expect that the results of the analysis point out the similarities in the short stories in characters' depiction as well as to show the extent to which the characters' identities depend on the surrounding space in each short story. In this way, the results will highlight the importance of spatial elements in characters' identity formation in Michela Murgia's short stories and also summarize the importance of the whole Murgia's literary opus.

Keywords: Italian literature, short stories, environment, spatial element, emotions, characters

Procedia PDF Downloads 57

Authors: Dhanuj M. Gandikota

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Sensor-derived three-dimensional (3D) point clouds of trees are invaluable in remote sensing analysis for the accurate measurement of key structural metrics, bio-inventory values, spatial planning/visualization, and ecological modeling. Machine learning (ML) holds the potential in addressing the restrictive tradeoffs in cost, spatial coverage, resolution, and information gain that exist in current point cloud sensing methods. Terrestrial laser scanning (TLS) remains the highest fidelity source of both canopy and below-canopy structural features, but usage is limited in both coverage and cost, requiring manual deployment to map out large, forested areas. While aerial laser scanning (ALS) remains a reliable avenue of LIDAR active remote sensing, ALS is also cost-restrictive in deployment methods. Space-borne photogrammetry from high-resolution satellite constellations is an avenue of passive remote sensing with promising viability in research for the accurate construction of vegetation 3-D point clouds. It provides both the lowest comparative cost and the largest spatial coverage across remote sensing methods. However, both space-borne photogrammetry and ALS demonstrate technical limitations in the capture of valuable below-canopy point cloud data. Looking to minimize these tradeoffs, we explored a class of powerful ML algorithms called Deep Learning (DL) that show promise in recent research on 3-D point cloud reconstruction and interpolation. Our research details the efficacy of applying these DL techniques to reconstruct accurate below-canopy point clouds from space-borne and aerial remote sensing through learned patterns of tree species fractal symmetry properties and the supplementation of locally sourced bio-inventory metrics. From our dataset, consisting of tree point clouds obtained from TLS, we deconstructed the point clouds of each tree into those that would be obtained through ALS and satellite photogrammetry of varying resolutions. We fed this ALS/satellite point cloud dataset, along with the simulated local bio-inventory metrics, into the DL point cloud reconstruction architectures to generate the full 3-D tree point clouds (the truth values are denoted by the full TLS tree point clouds containing the below-canopy information). Point cloud reconstruction accuracy was validated both through the measurement of error from the original TLS point clouds as well as the error of extraction of key structural metrics, such as crown base height, diameter above root crown, and leaf/wood volume. The results of this research additionally demonstrate the supplemental performance gain of using minimum locally sourced bio-inventory metric information as an input in ML systems to reach specified accuracy thresholds of tree point cloud reconstruction. This research provides insight into methods for the rapid, cost-effective, and accurate construction of below-canopy tree 3-D point clouds, as well as the supported potential of ML and DL to learn complex, unmodeled patterns of fractal tree growth symmetry.

Keywords: deep learning, machine learning, satellite, photogrammetry, aerial laser scanning, terrestrial laser scanning, point cloud, fractal symmetry

Procedia PDF Downloads 104

Authors: Mihir Hota, Namita Jena, S. N. Sahu

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LEEH (L-cysteine ethyl ester hydrochloride) capped CdS semiconductor nanocrystals are grown at 800C using a simple chemical route. Photoluminescence (PL), Optical absorption (UV) and Transmission Electron Microscopy (TEM) have been carried out to evaluate the structural and optical properties of the nanocrystal. Optical absorption studies have been carried out to optimize the sample. XRD and TEM analysis shows that the nanocrystal belongs to FCC structure having average size of 3nm while a bandgap of 2.84eV is estimated from Photoluminescence analysis. The nanocrystal emits bluish light when excited with 355nm LASER.

Keywords: cadmium sulphide, nanostructures, luminescence, optical properties

Procedia PDF Downloads 396

Authors: Naveed Zahra, Zahid Kamran, Shakeel Ahmad

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Heat stress is one of the most important environmental stressors challenging poultry production worldwide. The detrimental effect of heat stress results in reduction in the productive performance of poultry with high incidences of mortality. Researchers have made efforts to prevent such damage to poultry production through dietary manipulation. Supplementation with Chromium (Cr) might have some positive effects on some aspect of blood parameters and broilers performance. Chromium (Cr) the element whose trivalent Cr (III) organic state is present in trace amounts in animal feed and water is found to be a key element in evading heat stress and thus cutting down the heavy expenditure on air conditioning in broiler sheds. Chromium, along with other essential minerals is lost due to increased excretion during heat stress and thus its inclusion in broiler diet is kind of mandatory in areas of hot climate. Chromium picolinate in broiler diet has shown a hike in growth rate including muscle gain with body fat reduction under environmental stress. Fat reduction is probably linked to the ability of chromium to increase the sensitivity of the insulin receptors on tissues and thus the uptake of sugar from blood increases which decreases the amount of glucose to be converted to amino acids and stored in adipose tissue as triglycerides. Organic chromium has also shown to increase lymphocyte proliferation rate and antioxidant levels. So, the immune competency, muscle gain and fat reduction along with evasion of heat stress are good enough signs that indicate the fruitful inclusion of dietary chromium for broiler. This promising element may bring the much needed break in the local poultry industry. The task is now to set the exact dose of the element in the diet that would be useful enough and still not toxic to broiler. In conclusion there is a growing body of evidence which suggest that chromium may be an essential trace element for livestock and poultry. The nutritional requirement for chromium may vary with different species and physiological state within a species.

Keywords: broiler, chromium, heat stress, performance

Procedia PDF Downloads 289

Authors: Musa Momoh, A. U. Moreh, A. M. Bayawa, Sanusi Abdullahi, I. Atiku

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In this study, thin films of ZnO were synthesized by two techniques namely RF sputtering and spray pyrolysis. The films were deposited on corning glass. The primary materials used are 99.99% pure. The optical and structural properties of the samples were studied. It has been noted that the samples deposited by Spray pyrolysis have and average transmittance, refractive index and extinction coefficient as 80-90%, 1.33-1.44 and 13.11-27.52 respectively. Those deposited by sputtering method are 34-80%, 1.51-1.52 and 3.15-3.28. The XRD patterns of the samples show that they are polycrystalline.

Keywords: zinc oxide, spray pyrolysis, rf sputtering, optical properties, electrical properties

Procedia PDF Downloads 268

Authors: María Magdalena Méndez-González, Miguel García Rocha, Carlos Manuel Yermo De la Cruz

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Calcium phosphate (Ca5(PO4)3(X)) is widely used in orthopedic applications and is widely used as powder and granules. However, their presence in bone is in the form of nanometric needles 60 nm in length with a non-stoichiometric phase of apatite contains CO3-2, Na+, OH-, F-, and other ions in a matrix of collagen fibers. The crystal size, morphology control and interaction with cells are essential for the development of nanotechnology. The structural results of calcium phosphate, synthesized by chemical precipitation with crystal size of 22.85 nm are presented in this paper. The calcium phosphate powders were analyzed by X-ray diffraction, energy dispersive spectroscopy (EDS), infrared spectroscopy and FT-IR transmission electron microscopy. Network parameters, atomic positions, the indexing of the planes and the calculation of FWHM (full width at half maximum) were obtained. The crystal size was also calculated using the Scherer equation d (hkl) = cλ/βcosѲ. Where c is a constant related to the shape of the crystal, the wavelength of the radiation used for a copper anode is 1.54060Å, Ѳ is the Bragg diffraction angle, and β is the width average peak height of greater intensity. Diffraction pattern corresponding to the calcium phosphate called hydroxyapatite phase of a hexagonal crystal system was obtained. It belongs to the space group P63m with lattice parameters a = 9.4394 Å and c = 6.8861 Å. The most intense peak is obtained 2Ѳ = 31.55 (FWHM = 0.4798), with a preferred orientation in 121. The intensity difference between the experimental data and the calculated values is attributable to the temperature at which the sintering was performed. The intensity of the highest peak is at angle 2Ѳ = 32.11. The structure of calcium phosphate obtained was a hexagonal configuration. The intensity changes in the peaks of the diffraction pattern, in the lattice parameters at the corners, indicating the possible presence of a dopant. That each calcium atom is surrounded by a tetrahedron of oxygen and hydrogen was observed by infrared spectra. The unit cell pattern corresponds to hydroxyapatite and transmission electron microscopic crystal morphology corresponding to the hexagonal phase with a preferential growth along the c-plane was obtained.

Keywords: structure, nanoparticles, calcium phosphate, metallurgical and materials engineering

Procedia PDF Downloads 506

Authors: Shima Taheri, Simon Clark

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Concrete is an essential building material used in the majority of structures. Degradation of concrete over time increases the life-cycle cost of an asset with an estimated annual cost of billions of dollars to national economies. Most of the concrete failure occurs due to cracks, which propagate through a structure and cause weakening leading to failure. Stopping crack propagation is thus the key to protecting concrete structures from failure and is the best way to prevent inconveniences and catastrophes. Furthermore, the majority of cracks occur deep within the concrete in inaccessible areas and are invisible to normal inspection. Few materials intrinsically possess self-healing ability, but one that does is concrete. However, self-healing in concrete is limited to small dormant cracks in a moist environment and is difficult to control. In this project, we developed a method for self-healing of nascent fractures in concrete components through the automatic release of self-curing healing agents encapsulated in breakable nano- and micro-structures. The Poly(methyl methacrylate) (PMMA) based two-part adhesive is encapsulated in core-shell structures with brittle/weak inert shell, synthesized via miniemulsion/solvent evaporation polymerization. Stress fields associated with propagating cracks can break these capsules releasing the healing agents at the point where they are needed. The shell thickness is playing an important role in preserving the content until the final setting of concrete. The capsules can also be surface functionalized with carboxyl groups to overcome the homogenous mixing issues. Currently, this formulated self-healing system can replace up to 1% of cement in a concrete formulation. Increasing this amount to 5-7% in the concrete formulation without compromising compression strength and shrinkage properties, is still under investigation. This self-healing system will not only increase the durability of structures by stopping crack propagation but also allow the use of less cement in concrete construction, thereby adding to the global effort for CO2 emission reduction.

Keywords: self-healing concrete, concrete crack, concrete deterioration, durability

Procedia PDF Downloads 119