Search results for: inverse power law
1213 Transient Simulation Using SPACE for ATLAS Facility to Investigate the Effect of Heat Loss on Major Parameters
Authors: Suhib A. Abu-Seini, Kyung-Doo Kim
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A heat loss model for ATLAS facility was introduced using SPACE code predefined correlations and various dialing factors. As all previous simulations were carried out using a heat loss free input; the facility was considered to be completely insulated and the core power was reduced by the experimentally measured values of heat loss to compensate to the account for the loss of heat, this study will consider heat loss throughout the simulation. The new heat loss model will be affecting SPACE code simulation as heat being leaked out of the system throughout a transient will alter many parameters corresponding to temperature and temperature difference. For that, a Station Blackout followed by a multiple Steam Generator Tube Rupture accident will be simulated using both the insulated system approach and the newly introduced heat loss input of the steady state. Major parameters such as system temperatures, pressure values, and flow rates to be put into comparison and various analysis will be suggested upon it as the experimental values will not be the reference to validate the expected outcome. This study will not only show the significance of heat loss consideration in the processes of prevention and mitigation of various incidents, design basis and beyond accidents as it will give a detailed behavior of ATLAS facility during both processes of steady state and major transient, but will also present a verification of how credible the data acquired of ATLAS are; since heat loss values for steady state were already mismatched between SPACE simulation results and ATLAS data acquiring system. Acknowledgement- This work was supported by the Korean institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea.Keywords: ATLAS, heat loss, simulation, SPACE, station blackout, steam generator tube rupture, verification
Procedia PDF Downloads 2261212 Chemical Composition and Biological Properties of Algerian Honeys
Authors: Ouchemoukh Salim, Amessis-Ouchemoukh Nadia, Guenaoui Nawel, Moumeni Lynda, Zaidi Hicham, Otmani Amar, Sadou Dyhia
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Honey is a hive food rich in carbohydrates and water and it also has a lot of nutrients (enzymes, minerals, organic acids, phytochemicals...). It is used in different nutritional and therapeutic fields. Algerian honey was studied for its physicochemical parameters, nutritional values (moisture, brix, pH, electrical conductivity, and amounts of HMF, proteins, proline, total phenolic compounds and flavonoids) and some biological activities (antioxidant, anti-inflammatory and enzymatic anti-browning). The antioxidant activities of the samples were estimated using different methods (ABTS, DPPH free radicals scavenging, reducing power, and chelating ferrous activity). All honeys were acidic (3.45≤pH≤4.65). The color varied from mimosa yellow to dark brown. The specific rotation was levorotatory in most honey samples, and the electrical conductivity, hydroxymethylfurfural, and proline values agreed with the international honey requirements. For anti-inflammatory activity, the results showed that the inhibiting capacity of the denaturation of the BSA of the honey analyzed varied from 15 to 75 % with a maximum of activity at the concentration of 0,5 mg/ml. All honey exhibited enzymatic anti-browning on different slices of fruits. In fact, the results showed that the controls have the greatest browning unit compared to the honeys studied and PPO and POD enzymes had the lowest enzyme activity. High significant correlations were found between the color of honey, its antioxidant content and its biological activities (antioxidant, anti-inflammatory and enzymatic anti-browning). The dark color of honey is a good indicator of the best biological properties, therefore, the best nutritional and therapeutic values.Keywords: honey, physico-chemical parameters, bioactive compounds, biological properties
Procedia PDF Downloads 571211 The Nexus between Child Marriage and Women Empowerment with Physical Violence in Two Culturally Distinct States of India
Authors: Jayakant Singh, Enu Anand
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Background: Child marriage is widely prevalent in India. It is a form of gross human right violation that succumbs a child bride to be subservient to her husband within a marital relation. We investigated the relationship between age at marriage of women and her level of empowerment with physical violence experienced 12 months preceding the survey among young women aged 20-24 in two culturally distinct states- Bihar and Tamil Nadu of India. Methods: We used the information collected from 10514 young married women (20-24 years) at all India level, 373 in Bihar and 523 in Tamil Nadu from the third round of National Family Health Survey. Empowerment index was calculated using different parameters such as mobility, economic independence and decision making power of women using Principal Component Analysis method. Bivariate analysis was performed primarily using chi square for the test of significance. Logistic regression was carried out to assess the effect of age at marriage and empowerment on physical violence. Results: Lower level of women empowerment was significantly associated with physical violence in Tamil Nadu (OR=2.38, p<0.01) whereas child marriage (marriage before age 15) was associated with physical violence in Bihar (OR=3.27, p<0.001). The mean difference in age at marriage between those who experienced physical violence and those who did not experience varied by 7 months in Bihar and 10 months in Tamil Nadu. Conclusion: Culture specific intervention may be a key to reduction of violence against women as the results showed association of different factors contributing to physical violence in Bihar and Tamil Nadu. Marrying at an appropriate age perhaps is protective of abuse because it equips a woman to assert her rights effectively. It calls for an urgent consideration to curb both violence and child marriage with stricter involvement of family, civil society and the government. In the meanwhile physical violence may be recognized as a public health problem and integrate appropriate treatment to the victims within the health care institution.Keywords: child marriage, empowerment, India, physical violence
Procedia PDF Downloads 3131210 Understanding the Interactive Nature in Auditory Recognition of Phonological/Grammatical/Semantic Errors at the Sentence Level: An Investigation Based upon Japanese EFL Learners’ Self-Evaluation and Actual Language Performance
Authors: Hirokatsu Kawashima
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One important element of teaching/learning listening is intensive listening such as listening for precise sounds, words, grammatical, and semantic units. Several classroom-based investigations have been conducted to explore the usefulness of auditory recognition of phonological, grammatical and semantic errors in such a context. The current study reports the results of one such investigation, which targeted auditory recognition of phonological, grammatical, and semantic errors at the sentence level. 56 Japanese EFL learners participated in this investigation, in which their recognition performance of phonological, grammatical and semantic errors was measured on a 9-point scale by learners’ self-evaluation from the perspective of 1) two types of similar English sound (vowel and consonant minimal pair words), 2) two types of sentence word order (verb phrase-based and noun phrase-based word orders), and 3) two types of semantic consistency (verb-purpose and verb-place agreements), respectively, and their general listening proficiency was examined using standardized tests. A number of findings have been made about the interactive relationships between the three types of auditory error recognition and general listening proficiency. Analyses based on the OPLS (Orthogonal Projections to Latent Structure) regression model have disclosed, for example, that the three types of auditory error recognition are linked in a non-linear way: the highest explanatory power for general listening proficiency may be attained when quadratic interactions between auditory recognition of errors related to vowel minimal pair words and that of errors related to noun phrase-based word order are embraced (R2=.33, p=.01).Keywords: auditory error recognition, intensive listening, interaction, investigation
Procedia PDF Downloads 5151209 Three Decades of the Fourth Estate in Ghana: Issues, Challenges and the Way Forward
Authors: Samuel Pimpong
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In most liberal and constitutional democracies, the media serves as a dominant power in the construction of the fundamental building blocks for the consolidation of democratic governance. However, the extent to which the media can enhance democratic consolidation in a country depends to a large extent on the independence of the media, the robustness of legislative frameworks and the safety of journalists in discharging their duties without fear or favor. This study sought to examine pertinent issues, practices and challenges facing the media in Ghana’s Fourth Republic and attempts to make recommendations regarding the way forward. The work adopted a qualitative study approach. A total of sixteen (16) participants were purposively selected for face-to-face interviews. The study hinges on the democratic participant media theory and the development media theory. Primary data was analyzed via thematic analysis procedure. The study revealed that although Ghana has repealed its criminal libel laws, nonetheless other statutory Acts, such as the Electronic Communications Act 2008 (ACT 775) and the Criminal and other offences Act 1960 (Act 29), among others continue to stifle freedom of expression. On the other hand, press freedom is being abused by the use of fake content publication. Further, the study revealed that the absence of a comprehensive regulatory structure impedes the activities carried out by the media. Consequently, the study recommends a regulatory structure to oversee media activities and content, as the National Media Commission (NMC) lacks the authority to do so. In this direction, the study recommends a limitation on the role of the National Communications Authority (NCA) to administer broadcasting signals and transfer its licensing and sanctioning powers to the NMC in order to create one sole and completely independent media regulatory authority that deals with all media related issues.Keywords: media, constitutional democracy, democratic consolidation, fourth republic
Procedia PDF Downloads 741208 The Image of Saddam Hussein and Collective Memory: The Semiotics of Ba'ath Regime's Mural in Iraq (1980-2003)
Authors: Maryam Pirdehghan
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During the Ba'ath Party's rule in Iraq, propaganda was utilized to justify and to promote Saddam Hussein's image in the collective memory as the greatest Arab leader. Consequently, urban walls were routinely covered with images of Saddam. Relying on these images, the regime aimed to provide a basis for evoking meanings in the public opinion, which would supposedly strengthen Saddam’s power and reconstruct facts to legitimize his political ideology. Nonetheless, Saddam was not always portrayed with common and explicit elements but in certain periods of his rule, the paintings depicted him in an unusual context, where various historical and contemporary elements were combined in a narrative background. Therefore, an understanding of the implied socio-political references of these elements is required to fully elucidate the impact of these images on forming the memory and collective unconscious of the Iraqi people. To obtain such understanding, one needs to address the following questions: a) How Saddam Hussein is portrayed in mural during his rule? b) What of elements and mythical-historical narratives are found in the paintings? c) Which Saddam's political views were subject to the collective memory through mural? Employing visual semiotics, this study reveals that during Saddam Hussein's regime, the paintings were initially simple portraits but gradually transformed into narrative images, characterized by a complex network of historical, mythical and religious elements. These elements demonstrate the transformation of a secular-nationalist politician into a Muslim ruler who tried to instill three major policies in domestic and international relations i.e. the arabization of Iraq, as well as the propagation of pan-arabism ideology (first period), the implementation of anti-Israel policy (second period) and the implementation of anti-American-British policy (last period).Keywords: Ba'ath Party, Saddam Hussein, mural, Iraq, propaganda, collective memory
Procedia PDF Downloads 3281207 Gender Identify and Agency of Traumatized Subjects in Incestuous Family
Authors: Jenyu Peng
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Incestuous abuse can be considered a form of domestic violence that exemplifies gender inequality. It challenges the common image of home as “haven of safety”. In Taiwan, even after years of feminist NGOs’ effort to encourage victims to speak up, the shared cultural representations of family, still praising piety towards the parents, seem to keep the incest trauma in secret. As clinical practitioners have observed, most devastating psychological sequels of incest trauma are often related to silencing. Thus one can expect that in families centered cultures, the difficulties for victims to disclose are greater, and the traumatic consequences more severe. This poses crucial therapeutic issues for clinicians working in those cultures. Since 2009, the author, a trained psychoanalyst and researcher, has been conducting “clinical fieldwork” on incest trauma in Taiwan. Employing ethnographical method, our theoretical references are both psychoanalytical and anthropological. The necessity of interdisciplinary efforts in incest trauma research will be addressed and discussed. The analyses of the present paper will focus on five incestuous families: four Han families, and one aboriginal. Although Taiwanese aboriginal peoples have been pretty much sinicized since decades, it is worth observing the convergent and divergent aspects in these two cultures. Moreover, findings of a previous research conducted in France during 2002-2004 will serve as background for the purpose of comparison. The results will be presented along with three questions: 1) How the perception of family influences the process of disclosure? 2) How the incestuous experience comes into play with victims’ gender identity and sexuality, pivotal for the subjectification? 3) How victims more successful in gendered subjectification modify their dynamics with their traumatizing family? This research finds that most victims tend to defend their own incestuous families, and that victims’ subjectivity and agency are actually entangled in the power structure of incestuous family.Keywords: incestuous family, subjectification, gender identity, agency
Procedia PDF Downloads 3541206 Loss Function Optimization for CNN-Based Fingerprint Anti-Spoofing
Authors: Yehjune Heo
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As biometric systems become widely deployed, the security of identification systems can be easily attacked by various spoof materials. This paper contributes to finding a reliable and practical anti-spoofing method using Convolutional Neural Networks (CNNs) based on the types of loss functions and optimizers. The types of CNNs used in this paper include AlexNet, VGGNet, and ResNet. By using various loss functions including Cross-Entropy, Center Loss, Cosine Proximity, and Hinge Loss, and various loss optimizers which include Adam, SGD, RMSProp, Adadelta, Adagrad, and Nadam, we obtained significant performance changes. We realize that choosing the correct loss function for each model is crucial since different loss functions lead to different errors on the same evaluation. By using a subset of the Livdet 2017 database, we validate our approach to compare the generalization power. It is important to note that we use a subset of LiveDet and the database is the same across all training and testing for each model. This way, we can compare the performance, in terms of generalization, for the unseen data across all different models. The best CNN (AlexNet) with the appropriate loss function and optimizers result in more than 3% of performance gain over the other CNN models with the default loss function and optimizer. In addition to the highest generalization performance, this paper also contains the models with high accuracy associated with parameters and mean average error rates to find the model that consumes the least memory and computation time for training and testing. Although AlexNet has less complexity over other CNN models, it is proven to be very efficient. For practical anti-spoofing systems, the deployed version should use a small amount of memory and should run very fast with high anti-spoofing performance. For our deployed version on smartphones, additional processing steps, such as quantization and pruning algorithms, have been applied in our final model.Keywords: anti-spoofing, CNN, fingerprint recognition, loss function, optimizer
Procedia PDF Downloads 1371205 A Pedagogical Approach of Children’s Learning by Toys, Perspective: Bangladesh
Authors: Muktadir Ahmed, Sayed Akhlakur Rahaman, Mridha Shihab Mahmud
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The parents of Bangladesh have scarcity of knowledge about children play. Most of them do not know which toys are perfect for their children. Appropriate toys for playing is one of the most significant parts of children development from early age, besides for proper amelioration of children’s mental growth and brain capacities, toys play an emergent role. So selection of proper toy for children is very important. A toy forms the sagacity of a child and instructs child’s attitude. In this era of globalization to keep pace with everything children toys are also going forward but in a deleterious way. Maximum toys are now battery-driven and for this psychological developments of children are not increasing in effective way; therefore, pedagogical toys are proper selection. This type of toy inspires the wisdom and helps a child to reveal himself/herself. Pedagogical toys are attractive to children and help to stimulate their imagination. Pedagogical toys help them to build senso-motoric skills and hand-eye coordination. In this study, some children divided into two groups, one group played with pedagogical toys and another group played with conventional toys. This study is going to exhibit the difference between pedagogical and conventional toys for kids. The main aim of this study is to reveal the potency of pedagogical toy for children. To implement this study two Daycare Centers (DCC) Projapoti 1 & 3 of Mymensingh city had chosen. Every DCC having 1.5-6 years old children but for this study 2-5 years old children had been selected. The children of Projapoti-1 played with pedagogical toys and the children of Projapoti-2 played with conventional toys. After 6 weeks of study, the children of Projapoti-1 proved that they have improved their skills more than those children of Projapoti-3 who were playing with conventional toys. The children of Projapoti-1 have developed their touch sensation, muscular movement, imitation power, hand-eye coordination whereas the children of Projapoti-3 have only developed their muscular movement fairly (while running after battery driven toys) which is not better than those children of Projapoti-1. They cannot imitate like the children of Projapoti-1. They just had fun from playing virtual games, battery driven toys, watching cartoons etc. Actually, it is not possible to develop a child’s brain without pedagogical toy.Keywords: brain development, mental growth, pedagogical toys, play for children
Procedia PDF Downloads 3271204 Combustion Characteristics of Wet Woody Biomass in a Grate Furnace: Including Measurements within the Bed
Authors: Narges Razmjoo, Hamid Sefidari, Michael Strand
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Biomass combustion is a growing technique for heat and power production due to the increasing stringent regulations with CO2 emissions. Grate-fired systems have been regarded as a common and popular combustion technology for burning woody biomass. However, some grate furnaces are not well optimized and may emit significant amount of unwanted compounds such as dust, NOx, CO, and unburned gaseous components. The combustion characteristics inside the fuel bed are of practical interest, as they are directly related to the release of volatiles and affect the stability and the efficiency of the fuel bed combustion. Although numerous studies have been presented on the grate firing of biomass, to the author’s knowledge, none of them have conducted a detailed experimental study within the fuel bed. It is difficult to conduct measurements of temperature and gas species inside the burning bed of the fuel in full-scale boilers. Results from such inside bed measurements can also be applied by the numerical experts for modeling the fuel bed combustion. The current work presents an experimental investigation into the combustion behavior of wet woody biomass (53 %) in a 4 MW reciprocating grate boiler, by focusing on the gas species distribution along the height of the fuel bed. The local concentrations of gases (CO, CO2, CH4, NO, and O2) inside the fuel bed were measured through a glass port situated on the side wall of the furnace. The measurements were carried out at five different heights of the fuel bed, by means of a bent stainless steel probe containing a type-k thermocouple. The sample gas extracted from the fuel bed, through the probe, was filtered and dried and then was analyzed using two infrared spectrometers. Temperatures of about 200-1100 °C were measured close to the grate, indicating that char combustion is occurring at the bottom of the fuel bed and propagates upward. The CO and CO2 concentration varied in the range of 15-35 vol % and 3-16 vol %, respectively, and NO concentration varied between 10-140 ppm. The profile of the gas concentrations distribution along the bed height provided a good overview of the combustion sub-processes in the fuel bed.Keywords: experimental, fuel bed, grate firing, wood combustion
Procedia PDF Downloads 3281203 The Effects of Training Load on Some Selected Fitness Variables in the Case of U-17 Female Volleyball Project Players, Central Ethiopia
Authors: Behailu Shigute Habtemariam
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The aim of the study was to examine the effects of training load on some selected fitness performance variables of volleyball players in the case of U-17 female volleyball project players in the central Ethiopia region. Methods: In this study, quasi-experimental design was used. For the purpose of this study, twenty-three volleyball players were used as a subject from the two projects. The data collected through fitness performance assessment were analyzed and interpreted into a meaningful idea using manually as well as with computer in order to compare physical fitness variables and changes observed among participants. Those are taking part in the effects of training load on some selected physical fitness variables. The collected data were analyzed by means of the Statistical Package for Social Science version (SPSS V 20). The independent t-test was used to show the mean differences between the groups, and the paired T-test was used to compare the mean differences of the pre and post-training within each group. The level of significance will be set at Alfa 0.05. Results: The results are displayed using tables and figures. A significant difference was found in the mean differences of pre-test values (19.7 cm) and post-test values (37.5 cm) of the Durame city project on the flexibility test (MD =17.8 cm, P = 0.00). On the other hand, there was a significant difference in the mean difference of pre-test values of (18 cm) and post-test values (26.3 cm) of the Hosana city project on the flexibility test ( MD = 8.3 cm, P = 0.00). Conclusion: According to the results of the present studies, there were significant improvements from pre to post-test at Durame City and Hosana City projects on agility, flexibility, power, and speed fitness tests. On the other hand, a significant difference was not found before beginning the exercise between the two projects; however, a significant difference was found after 12 weeks of training.Keywords: overload, performance, training, volleyball
Procedia PDF Downloads 1001202 Ability of Gastric Enzyme Extract of Adult Camel to Clot Bovine Milk
Authors: Boudjenah-Haroun Saliha, Isselnane Souad, Nouani Abdelwahab, Baaissa Babelhadj, Mati Abderrahmane
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Algeria is experiencing significant development of the dairy sector, where consumption of milk and milk products increased by 2.7 million tons in 2008 to 4,400,000 tons in 2013, and cheese production has reached 1640 tons in the year 2014 with average consumption of 0.7 kg/person/year. Although rennet is still the most used coagulating enzyme in cheese, its production has been growing worldwide shortage. This shortage is primarily due to a growing increase in the production and consumption of cheese, and the inability to increase in parallel the production of rennet. This shortage has caused very large fluctuations in its price). To overcome these obstacles, much research has been undertaken to find effective and competitive substitutes used industrially. For this, the selection of a local production of rennet substitute is desirable. It would allow a permanent supply with limited dependence on imports and price fluctuations. Investigations conducted by our research team showed that extracts coagulants from the stomachs of older camels are characterized by a coagulating power than those from younger camels. The objective of this work is to study the possibility of substituting commercial rennet coagulant by gastric enzymes from adult camels for coagulation bovine milk. Excerpts from the raw camel coagulants obtained are characterized through their teneures proteins and clotting and proteolytic activities. Milk clotting conditions by the action of these extracts were optimized. Milk clotting time all treated with enzyme preparations and under different conditions was calculated. Bovine rennet has been used for comparison. The results show that crude extracts from gastric adult camel can be good substituting bovine rennet.Keywords: Algeria, camel, cheese, coagulation, gastric extracts, milk
Procedia PDF Downloads 4421201 Contribution Of Community-based House To House (H2h) Active Tuberculosis (Tb) Case Finding (Acf) To Increase In Tb Notification In Nigeria: Kano State Experience 2012 To 2022
Authors: Ibrahim Umar, S Chindo, A Rajab
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Background: TB remains a disease of public health concern in Nigeria with an estimated incidence rate of 219/100,000. Kano has the second highest TB burden in Nigeria and is the leading state with the highest consistent yearly TB notification. House-to-house (H2H) active case search in the community was found to have major contribution to the total TB notification in the state. Aims and Objective: To showcase the impact of H2H community active TB case search (ACF) to yearly TB notification in Kano State, Northern Nigeria from 2012 to 2022. Methodology: This is a retrospective descriptive study based on the analysis of data collected during the routine quarterly and yearly TB data collected in the state. Data was analyzed using the Power BI with statistical alpha level of significance <0.05. Results: Between 2012 and 2013 there was no House-to-house active TB case search in Nigeria and Kano had zero contribution to TB notification from the community in those years. However, in 2014 with the introduction of H2H Active TB Case Search Kano notified 6,014 TB cases out of which 113 came from the community ACF that translated to 2% contribution to total TB notification. From 2014 to 2022 there was progressive increase in community contribution to TB case notification from 113 out of 6,014 total TB patients notified (2012) to 11,799 out of 26,371 TB patients notified (2022) in Kano State. This translated to 45% increase in community contribution to total TB case notification. Discussion: Remarkable increase in community contribution to total TB case notification in Kano State was achieved in 2022 with 11,799 TB cases notified from the community Active TB case search to the total of 26,731 TB cases notified in Kano State, Nigeria. Conclusion: in research has shown that Community-based H2H Active TB Case Search through Community TB Workers (CTWs) is an excellent strategy in finding the missing TB cases towards Ending TB in the world.Keywords: tuberculosis(TB), active case search (ACF), house-to-house (H2H), community TB workers (CTWs)
Procedia PDF Downloads 961200 Impact of Social Crisis on Property Market Performance and Evolving Strategy for Improved Property Transactions in Crisis Prone Environment: A Case Study of North Eastern Nigeria
Authors: A. Yakub AbdurRaheem
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Urban violence in the form of ethnic and religious conflicts have been on the increase in many African cities in the recent years of which most of them are the result of intense and bitter competition for political power, the control of limited economic, social and environmental resources. In Nigeria, the emergence of the Boko Haram insurgency in most parts of the northeastern parts have ignited violence, bloodshed, refugee exodus and internal migration. Not only do the persistent attacks of the sect create widespread insecurity and fear, but it has also stifled normal processes of trade and investments most especially real property investment which is acclaimed to accelerate the economic cycle, thus the need to evolve strategies for an improved property market in such areas. This paper, therefore, examines the impact of this social crisis on effective and efficient utilization of real properties as a resource towards the development of the economy, using a descriptive analysis approach where particular emphasis was based on trends in residential housing values; volume of estimated property transactions and real estate investment decisions by affected individuals. Findings indicate that social crisis in the affected areas have been a clog on the wheels of property development and investment as properties worth hundreds of millions have been destroyed thereby having great impact on property values. Based on these findings, recommendations were made to include the need to strategically continue investing in property during such times, the need for Nigerian government to establish an active conflict monitoring and management unit for the prompt response, encourage community and neighborhood policing to ameliorate security challenges in Nigeria.Keywords: social crisis, economy, resources, property market
Procedia PDF Downloads 2381199 Modeling and Design of E-mode GaN High Electron Mobility Transistors
Authors: Samson Mil'shtein, Dhawal Asthana, Benjamin Sullivan
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The wide energy gap of GaN is the major parameter justifying the design and fabrication of high-power electronic components made of this material. However, the existence of a piezo-electrics in nature sheet charge at the AlGaN/GaN interface complicates the control of carrier injection into the intrinsic channel of GaN HEMTs (High Electron Mobility Transistors). As a result, most of the transistors created as R&D prototypes and all of the designs used for mass production are D-mode devices which introduce challenges in the design of integrated circuits. This research presents the design and modeling of an E-mode GaN HEMT with a very low turn-on voltage. The proposed device includes two critical elements allowing the transistor to achieve zero conductance across the channel when Vg = 0V. This is accomplished through the inclusion of an extremely thin, 2.5nm intrinsic Ga₀.₇₄Al₀.₂₆N spacer layer. The added spacer layer does not create piezoelectric strain but rather elastically follows the variations of the crystal structure of the adjacent GaN channel. The second important factor is the design of a gate metal with a high work function. The use of a metal gate with a work function (Ni in this research) greater than 5.3eV positioned on top of n-type doped (Nd=10¹⁷cm⁻³) Ga₀.₇₄Al₀.₂₆N creates the necessary built-in potential, which controls the injection of electrons into the intrinsic channel as the gate voltage is increased. The 5µm long transistor with a 0.18µm long gate and a channel width of 30µm operate at Vd=10V. At Vg =1V, the device reaches the maximum drain current of 0.6mA, which indicates a high current density. The presented device is operational at frequencies greater than 10GHz and exhibits a stable transconductance over the full range of operational gate voltages.Keywords: compound semiconductors, device modeling, enhancement mode HEMT, gallium nitride
Procedia PDF Downloads 2621198 Experimental Study of Complete Loss of Coolant Flow (CLOF) Test by System–Integrated Modular Advanced Reactor Integral Test Loop (SMART-ITL) with Passive Residual Heat Removal System (PRHRS)
Authors: Jin Hwa Yang, Hwang Bae, Sung Uk Ryu, Byong Guk Jeon, Sung Jae Yi, Hyun Sik Park
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Experimental studies using a large-scale thermal-hydraulic integral test facility, System–integrated Modular Advanced Reactor Integral Test Loop (SMART-ITL), have been carried out to validate the performance of the prototype, SMART. After Fukushima accident, the passive safety systems have been dealt as important designs for retaining of nuclear safety. One of the concerned scenarios for evaluating the passive safety system is a Complete Loss of Coolant Flow (CLOF). The flowrate of coolant in the primary system is maintained by Reactor Coolant Pump (RCP). When the supply of electric power of RCP is shut off, the flowrate of coolant decreases sharply, and the temperature of the coolant increases rapidly. Therefore, the reactor trip signal is activated to prevent the over-heating of the core. In this situation, Passive Residual Heat Removal System (PRHRS) plays a significant role to assure the soundness of the SMART. The PRHRS using a two-phase natural circulation is a passive safety system in the SMART to eliminate the heat of steam generator in the secondary system with heat exchanger submarined in the Emergency Cooling Tank (ECT). As the RCPs continue to coast down, inherent natural circulation in the primary system transfers heat to the secondary system. The transferred heat is removed by PRHRS in the secondary system. In this paper, the progress of the CLOF accident is described with experimental data of transient condition performed by SMART-ITL. Finally, the capability of passive safety system and inherent natural circulation will be evaluated.Keywords: CLOF, natural circulation, PRHRS, SMART-ITL
Procedia PDF Downloads 4421197 Digital Female Entrepreneurs in South Africa: Drivers and Relationship to Economic Development
Authors: C. van den Berg, C. Pokpas
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Popular discourse touts entrepreneurship as a universal solution for underdevelopment, unemployment, and poverty. Moreover, claims are made that women and other disadvantaged groups can achieve material and personal success through digital entrepreneurship. This paper examines the potential of digital technology in entrepreneurial ventures to stimulate economic growth for marginalized groups and communities. Although digital entrepreneurship is hailed as a means to empower under-resourced and socially marginalized people, these opportunities still exist within the confines of existing social and cultural practices. The perspectives of female digital entrepreneurs in developing countries are sorely understudied, particularly concerning an understanding of the complex underlying socio-cultural factors impeding women’s entrepreneurial behaviors. This qualitative study, guided by a feminist phenomenological perspective, focused on the experiences of digital female entrepreneurs in the Western Cape of South Africa. Data were collected via semi-structured interviews and analyzed through the interpretative phenomenological analysis (IPA) approach to determine the relationships between digital entrepreneurship and structural and agential enabling conditions. Findings show that digital entrepreneurship is not a panacea for economic growth in marginalized groups and communities and highlight the importance of addressing socio-cultural gender inequality to enable successful entrepreneurial activity. The paper concludes with recommendations for specialized training initiatives aimed at female entrepreneurs that address internalized constraints and barriers that keep women subservient and measures to shift gender and power beliefs. The outcome will benefit the stimulation of gender-specific public policies to develop a successful digital start-up ecosystem further.Keywords: digital innovation, female digital entrepreneurs, feminist phenomenology, gender, marginalised communities
Procedia PDF Downloads 1361196 Potential Use of Thymus mastichina L. Extract as a Natural Agent against Cheese Spoilage Microorganisms
Authors: Susana P. Dias, Andrea Gomes, Fernanda M. Ferreira, Marta F. Henriques
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Thymus mastichina L. is an endogenous medicinal and aromatic plant of the Mediterranean flora. It has been used empirically over the years as a natural preservative in food. Nowadays, the antimicrobial activity of its bioactive compounds, such as essential oils and extracts, has been well recognized. The main purpose of this study was to evaluate the antimicrobial effect of Thymus mastichina ethanolic and aqueous extracts on pathogens and spoilage microorganisms present in cheese during ripening. The effect that the extract type and its concentration has on the development of Staphylococcus aureus, Escherichia coli, and Yarrowia lipolytica populations during 24 hours, was studied 'in vitro' using appropriate culture media. The results achieved evidenced the antimicrobial activity of T. mastichina extracts against the studied strains, and the concentration of 2 mg/mL (w/v) was selected and used directly on the cheese surface during ripening. In addition to the microbiological evaluation in terms of total aerobic bacteria, Enterobacteriaceae, yeasts (particularly Y. lipolytica) and molds, the treated cheeses physicochemical evaluation (humidity, aw, pH, colour, and texture) was also performed. The results were compared with cheeses with natamicyn (positive control) and without any treatment (negative control). The physicochemical evaluation showed that the cheeses treated with ethanolic extract of Thymus mastichina, except the fact that they lead to a faster water loss during ripening, did not present considerable differences when compared to controls. The study revealed an evident antimicrobial power of the extracts, although less effective than the one shown by the use of natamycin. For this reason, the improvement of the extraction methods and the adjustment of the extract concentrations will contribute to the use of T. mastichina as a healthier and eco-friendly alternative to natamycin, that is also more attractive from an economic point of view.Keywords: antimicrobial activity, cheese, ethanolic extract, Thymus mastichina
Procedia PDF Downloads 1761195 Software Development to Empowering Digital Libraries with Effortless Digital Cataloging and Access
Authors: Abdul Basit Kiani
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The software for the digital library system is a cutting-edge solution designed to revolutionize the way libraries manage and provide access to their vast collections of digital content. This advanced software leverages the power of technology to offer a seamless and user-friendly experience for both library staff and patrons. By implementing this software, libraries can efficiently organize, store, and retrieve digital resources, including e-books, audiobooks, journals, articles, and multimedia content. Its intuitive interface allows library staff to effortlessly manage cataloging, metadata extraction, and content enrichment, ensuring accurate and comprehensive access to digital materials. For patrons, the software offers a personalized and immersive digital library experience. They can easily browse the digital catalog, search for specific items, and explore related content through intelligent recommendation algorithms. The software also facilitates seamless borrowing, lending, and preservation of digital items, enabling users to access their favorite resources anytime, anywhere, on multiple devices. With robust security features, the software ensures the protection of intellectual property rights and enforces access controls to safeguard sensitive content. Integration with external authentication systems and user management tools streamlines the library's administration processes, while advanced analytics provide valuable insights into patron behavior and content usage. Overall, this software for the digital library system empowers libraries to embrace the digital era, offering enhanced access, convenience, and discoverability of their vast collections. It paves the way for a more inclusive and engaging library experience, catering to the evolving needs of tech-savvy patrons.Keywords: software development, empowering digital libraries, digital cataloging and access, management system
Procedia PDF Downloads 841194 Challenges of Implementing Participatory Irrigation Management for Food Security in Semi Arid Areas of Tanzania
Authors: Pilly Joseph Kagosi
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The study aims at assessing challenges observed during the implementation of participatory irrigation management (PIM) approach for food security in semi-arid areas of Tanzania. Data were collected through questionnaire, PRA tools, key informants discussion, Focus Group Discussion (FGD), participant observation, and literature review. Data collected from the questionnaire was analysed using SPSS while PRA data was analysed with the help of local communities during PRA exercise. Data from other methods were analysed using content analysis. The study revealed that PIM approach has a contribution in improved food security at household level due to the involvement of communities in water management activities and decision making which enhanced the availability of water for irrigation and increased crop production. However, there were challenges observed during the implementation of the approach including; minimum participation of beneficiaries in decision-making during planning and designing stages, meaning inadequate devolution of power among scheme owners. Inadequate and lack of transparency on income expenditure in Water Utilization Associations’ (WUAs), water conflict among WUAs members, conflict between farmers and livestock keepers and conflict between WUAs leaders and village government regarding training opportunities and status; WUAs rules and regulation are not legally recognized by the National court and few farmers involved in planting trees around water sources. However, it was realized that some of the mentioned challenges were rectified by farmers themselves facilitated by government officials. The study recommends that the identified challenges need to be rectified for farmers to realize impotence of PIM approach as it was realized by other Asian countries.Keywords: challenges, participatory approach, irrigation management, food security, semi arid areas
Procedia PDF Downloads 3271193 Gender and Sustainable Rural Tourism: A Study into the Experiences and the Roles of Local Women in the Sundarbans Area of Bangladesh
Authors: Jakia Rajoana
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The key aim of this research is to achieve Sustainable Rural Tourism (SRT) through women’s empowerment in the Sundarbans area of Bangladesh. Women in rural areas in developing countries depend on biomass for their survival and that of their family. Yet they have an unequal access to resources as well as decision making, thus making them more vulnerable to any changes in the environment. Women in the developing countries experience gender inequality which is culturally embedded resulting into women having less access to and control over financial and material resources, information, and also a lack of recognition of their contribution as compared to men. Their disadvantaged social position is augmented by their extreme poverty, little or no power they have over their own lives vis-à-vis the disproportionate burden they bear in reproduction and child-raising. Despite the significance of the need to pay attention to gender related issues in sustainable rural tourism (SRT), research remains rather scant. For instance, there is very little research that illustrates the role of women in tourism in the Sundarbans area. Thus empirically, this research seeks to fill a significant gap by focusing on rural areas and in particular focus on considerably under-researched area, namely the Sundarbans women’s role in tourism. In order to fully comprehend their experiences and life stories, this research will apply the empowerment theory and consider it along with the research on sustainable rural tourism. Since, women’s empowerment can act as a potential tool for SRT development and also examine the role tourism plays in the lives of Sundarbans’ women. Methodologically, this study will follow a qualitative research design using an ethnographic approach. Participant observation, semi- structured interviews, and documentation will be the primary data collection instruments in four communities – Shayamnagar, Koyra, Mongla and Sarankhola – in the Sundarbans area. It is hoped that by focusing on the life stories of these invisible women, research is better able to engage with nuances inherent in marginal and significantly under-researched communities.Keywords: gender, sustainable rural tourism, women empowerment, Sundarbans
Procedia PDF Downloads 3021192 Fundamental Research on Factors Affecting the Under-Film Corrosion Behavior of Coated Steel Members
Authors: T. Sakamoto, S. Kainuma
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Firstly, in order to examine the influence of the remaining amount of the rust on the coating film durability, the accelerated deterioration tests were carried out. In order to prepare test specimens, uncoated steel plates were corroded by the Salt Spray Test (SST) prior to the accelerated deterioration tests, and then the prepared test specimens were coated by epoxy resin and phthalic acid resin each of which has different gas-barrier performance. As the result, it was confirmed that the under-film corrosion occurred in the area and the adjacency to great quantities of salt exists in the rust, and did not occurred in the specimen which was applied the epoxy resin paint after the surface preparation by the power tool. Secondly, in order to clarify the influence of the corrosive factors on the coating film durability, outdoor exposure tests were conducted for one year on actual steel bridge located at a coastal area. The tests specimens consist of coated corroded plates and the uncoated steel plates, and they were installed on the different structural members of the bridge for one year. From the test results, the uncoated steel plates which were installed on the underside of the member are easily corrosive and had highly correlation with the amount of salt in the rust. On the other hand, the most corrosive under-film steel was the vertical surface of the web plate. Thus, it was confirmed that under-film corrosion rate was not match with corrosion rate of the uncoated steel. Consequently, it is estimated that the main factors of under-film corrosion are gas-barrier property of coating film and corrosive factors such as water vapor and temperature. The salt which significantly corrodes the uncoated steel plate is not directly related to the under-film corrosion.Keywords: accelerated deterioration test, coating durability, environmental factor, under-film corrosion
Procedia PDF Downloads 3711191 Molecular Engineering of Intrinsically Microporous Polybenzimidazole for Energy-efficient Gas Separation
Authors: Mahmoud Abdulhamid, Rifan Hardian, Prashant Bhatt, Shuvo Datta, Adrian Ramirez, Jorge Gascon, Mohamed Eddaoudi, Gyorgy Szekely
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Polybenzimidazole (PBI) is a high-performance polymer that exhibits high thermal and chemical stability. However, it suffers from low porosity and low fractional free volume, which hinder its application as separation material. Herein, we demonstrate the molecular engineering of gas separation materials by manipulating a PBI backbone possessing kinked moieties. PBI was selected as it contains NH groups which increase the affinity towards CO₂, increase sorption capacity, and favors CO₂ over other gasses. We have designed and synthesized an intrinsically microporous polybenzimidazole (iPBI) featuring a spirobisindane structure. Introducing a kinked moiety in conjunction with crosslinking enhanced the polymer properties, markedly increasing the gas separation performance. In particular, the BET surface area of PBI increased 30-fold by replacing a flat benzene ring with a kinked structure. iPBI displayed a good CO₂ uptake of 1.4 mmol g⁻¹ at 1 bar and 3.6 mmol g⁻¹ at 10 bar. Gas sorption uptake and breakthrough experiments were conducted using mixtures of CO₂/CH₄ (50%/50%) and CO₂/N₂ (50%/50%), which revealed the high selectivity of CO₂ over both CH₄ and N₂. The obtained CO₂/N₂ selectivity is attractive for power plant flue gas application requiring CO₂ capturing materials. Energy and process simulations of biogas CO₂ removal demonstrated that up to 70% of the capture energy could be saved when iPBI was used rather than the current amine technology (methyl diethanolamine [MDEA]). Similarly, the combination of iPBI and MDEA in a hybrid system exhibited the highest CO₂ capture yield (99%), resulting in nearly 50% energy saving. The concept of enhancing the porosity of PBI using kinked moieties provides new scope for designing highly porous polybenzimidazoles for various separation processes.Keywords: polybenzimidazole (PBI), intrinsically microporous polybenzimidazole (iPBI), gas separation, pnergy and process simulations
Procedia PDF Downloads 921190 Understanding the Factors behind Graduate Employability in the United Arab Emirates
Authors: Mohammed Islam
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Graduate employability is a well debated topic by governments, employers, and higher education institutes (HEI) across the world. Much of the focus of these debates have centred around the skills that graduates bring or should bring to the job market, a point echoed by United Arab Emirates (UAE) policy makers and employers. While some research has been carried out on graduates' employability skills, little or no attention has been paid to the forces at play in developing employability policy and its subsequent implementation. The focus of debate has been on a perceived skills gap rather than policy. Recognising a gap in the literature, this paper details a study of UAE employability policy development. Taking a social constructionist approach, this case study views policy as discursive and socially constructed through interactions with key stakeholders. It is within the myriad of interdependent socio-political factors and social practices, particularly power relationships, that this paper explores UAE policy on graduate employability. In doing so, this adds to the debate on graduate employability from the perspective of policy and explores its roots in the interaction between human activity and the ‘system’. Data was collected from two main sources: documentary review and semi-structured interviews. Policies and publicly stated rhetoric on graduate employability were analysed using Critical Discourse Analysis. Semi-structured interviews with representatives from policy makers, HEIs, and employers were reviewed through Thematic Analysis. The theoretical framework for the discussion of findings draws from social practice theories and highlights the factors at play in access to employment for UAE graduates. This case study presents a methodological approach to policy studies that can be applied beyond the context under investigation. Education policy researchers are provided with an opportunity to compare similarities and differences with their own specific contexts.Keywords: critical discourse analysis, employability, methodology, policy, social constructionism
Procedia PDF Downloads 1291189 Energy Options and Environmental Impacts of Carbon Dioxide Utilization Pathways
Authors: Evar C. Umeozor, Experience I. Nduagu, Ian D. Gates
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The energy requirements of carbon dioxide utilization (CDU) technologies/processes are diverse, so also are their environmental footprints. This paper explores the energy and environmental impacts of systems for CO₂ conversion to fuels, chemicals, and materials. Energy needs of the technologies and processes deployable in CO₂ conversion systems are met by one or combinations of hydrogen (chemical), electricity, heat, and light. Likewise, the environmental footprint of any CO₂ utilization pathway depends on the systems involved. So far, evaluation of CDU systems has been constrained to particular energy source/type or a subset of the overall system needed to make CDU possible. This introduces limitations to the general understanding of the energy and environmental implications of CDU, which has led to various pitfalls in past studies. A CDU system has an energy source, CO₂ supply, and conversion units. We apply a holistic approach to consider the impacts of all components in the process, including various sources of energy, CO₂ feedstock, and conversion technologies. The electricity sources include nuclear power, renewables (wind and solar PV), gas turbine, and coal. Heat is supplied from either electricity or natural gas, and hydrogen is produced from either steam methane reforming or electrolysis. The CO₂ capture unit uses either direct air capture or post-combustion capture via amine scrubbing, where applicable, integrated configurations of the CDU system are explored. We demonstrate how the overall energy and environmental impacts of each utilization pathway are obtained by aggregating the values for all components involved. Proper accounting of the energy and emission intensities of CDU must incorporate total balances for the utilization process and differences in timescales between alternative conversion pathways. Our results highlight opportunities for the use of clean energy sources, direct air capture, and a number of promising CO₂ conversion pathways for producing methanol, ethanol, synfuel, urea, and polymer materials.Keywords: carbon dioxide utilization, processes, energy options, environmental impacts
Procedia PDF Downloads 1491188 Harnessing Community Benefits; Case Study of REDD+ in Ghana
Authors: Abdul-Razak Saeed
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Addressing the climate change crisis that this generation faces has evolved to include the consideration of a policy mechanism referred to as reduced emissions from deforestation and forest degradation with plus components of conservation, sustainable forest management and enhancement of forest carbon stocks (REDD+). REDD+ emerged from the International level of UNFCCC but its implementation is by developing countries. It challenges the development paradigm of nations that depend on the unsustainable clearing of forests and land use change for economic development whilst posing as an opportunity or risk for forest community livelihoods, institutions and their interaction with the forest resources. As a novel policy mechanism, it is imperative to gain global insight into local contexts of its implementation and to understand local level mobilization of their agency for institutional sustainability as reconfigured by new carbon economy initiatives like REDD+. Using a systematic review process, as the initial stages of this study, secondary data of REDD+ projects across the globe were evaluated to pick up gaps in research and that of on ground REDD+ implementation. Primary data was gathered from 30 actors in the government, NGO, private sector and traditional authorities using face-to-face semi structured interviews in Ghana; participation in meetings and workshops and policy and strategy document reviews. Preliminary findings of the study include REDD+ knowledge being a key determinant of power distribution and affects who shapes the process; in Ghana, informal relationships are playing key roles in advancing REDD+ unlike in traditional forestry and a subjectivity shift of local communities from an 'emotive-link' of environmental care to one of 'economic self-seeking and enriching' domain of thought.Keywords: climate change, communities, forests, REDD+
Procedia PDF Downloads 3711187 Studies on Space-Based Laser Targeting System for the Removal of Orbital Space Debris
Authors: Krima M. Rohela, Raja Sabarinath Sundaralingam
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Humans have been launching rockets since the beginning of the space age in the late 1950s. We have come a long way since then, and the success rate for the launch of rockets has increased considerably. With every successful launch, there is a large amount of junk or debris which is released into the upper layers of the atmosphere. Space debris has been a huge concern for a very long time now. This includes the rocket shells released from the launch and the parts of defunct satellites. Some of this junk will come to fall towards the Earth and burn in the atmosphere. But most of the junk goes into orbit around the Earth, and they remain in orbits for at least 100 years. This can cause a lot of problems to other functioning satellites and may affect the future manned missions to space. The main concern of the space-debris is the increase in space activities, which leads to risks of collisions if not taken care of soon. These collisions may result in what is known as Kessler Syndrome. This debris can be removed by a space-based laser targeting system. Hence, the matter is investigated and discussed. The first step in this involves launching a satellite with a high-power laser device into space, above the debris belt. Then the target material is ablated with a focussed laser beam. This step of the process is highly dependent on the attitude and orientation of the debris with respect to the Earth and the device. The laser beam will cause a jet of vapour and plasma to be expelled from the material. Hence, the force is applied in the opposite direction, and in accordance with Newton’s third law of motion, this will cause the material to move towards the Earth and get pulled down due to gravity, where it will get disintegrated in the upper layers of the atmosphere. The larger pieces of the debris can be directed towards the oceans. This method of removal of the orbital debris will enable safer passage for future human-crewed missions into space.Keywords: altitude, Kessler syndrome, laser ablation, Newton’s third law of motion, satellites, Space debris
Procedia PDF Downloads 1501186 The Three-Dimensional Kinematics of the Sprint Start in Young Elite Sprinters
Authors: Saeed Ilbeigi, Bart Van Gheluwe
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The purpose of this study was to identify the three-dimensional kinematics of the sprint start during the start phase of the sprint. The purpose of this study was to identify the three-dimensional kinematics of the sprint start during the start phase of the sprint. Moreover, the effect of anthropometrical factors such as skeletal muscle mass, thigh girth, and calf girth also were considered on the kinematics of the sprint start. Among all young sprinters involved in the national Belgium league, sixty sprinters (boys: 14.7 ± 1.8 years and girls: 14.8±1.5 years) were randomly selected. The kinematics data of the sprint start were collected with a Vicon® 620 motion analysis system equipped with 12 infrared cameras running at 250 Hz and running the Vicon Data Station software. For statistical analysis, T-tests and ANOVA׳s with Scheffé post hoc test were used and the significant level was set as p≤0.05. The results showed that the angular positions of the lower joints of the young sprinters in the set position were comparable with adult figures from literature, however, with a greater range of joint extension. The most significant difference between boys and girls was found in the set position, where the boys presented a more dorsiflexed ankle. No further gender effect was observed during the leaving the blocks and contact phase. The sprinters with a higher age, skeletal muscle mass, thigh girth, and calf girth displayed a better angular position of the lower joints (e.g. ankle, knee, hip) in the set position, a more optimal angular position for the foot and knee for absorbing impact forces at foot contact and finally a higher range of flexion/extension motion to produce force and power when leaving the blocks.Keywords: anthropometry, kinematics, sprint start, young elite sprinters
Procedia PDF Downloads 2301185 Impact of Crime on Women and Their Families in Rural Areas of Haryana State in India
Authors: Rashmi Tyagi, Savita Vermani
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Violence against women is the result of long-standing power imbalance between men and women and thus seriously compromises the well-being, productivity and contribution of one half the population. The costs incurred to the family especially children and society at large in terms of physical, psychological, social and financial losses are huge. The communities’ native to the state of Haryana in India is primarily patriarchal, burdened with age old regressive mindset under the socio-cultural and religious structures which discriminates against women. Therefore it was important to bring to light the issues affecting women in this region. Therefore this study focused on studying the consequences of crime on victim women and their families. Two hundred women were randomly selected and out of those one hundred twenty, who were affected with some kind of violence were interviewed. Data was collected and statistically analyzed for physical, psychological, inter-family and societal consequences of violence on these women. Women reported physical injuries, gynecological problems, unwanted pregnancies, frigidity, phobia and sexual dysfunction. 58.9% women felt decreased work efficiency. Psychological problems encountered were anxiety, isolation, depression, suicidal tendencies. 66.7% respondents suffered from anxiety followed by 65.0% faced depression symptoms. At family levels, 40.0% respondents felt the atmosphere was unsuitable for children while 39.2% reported lack of interaction. The societal consequences reported were breakdown of interaction with friends and family (44.2%) and resulting humiliation and demeaning remarks from others (38.3%). The impact of violence on women had an adverse effect on children. 36.7% children felt responsible for abuse and powerless to stop it, 29.2% reported living with fear. Concerted efforts are required to curb violence against women in Haryana.Keywords: impact of violence against women on children, patriarchal society, physical psychological and societal consequences, violence against women
Procedia PDF Downloads 3081184 Globally Convergent Sequential Linear Programming for Multi-Material Topology Optimization Using Ordered Solid Isotropic Material with Penalization Interpolation
Authors: Darwin Castillo Huamaní, Francisco A. M. Gomes
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The aim of the multi-material topology optimization (MTO) is to obtain the optimal topology of structures composed by many materials, according to a given set of constraints and cost criteria. In this work, we seek the optimal distribution of materials in a domain, such that the flexibility of the structure is minimized, under certain boundary conditions and the intervention of external forces. In the case we have only one material, each point of the discretized domain is represented by two values from a function, where the value of the function is 1 if the element belongs to the structure or 0 if the element is empty. A common way to avoid the high computational cost of solving integer variable optimization problems is to adopt the Solid Isotropic Material with Penalization (SIMP) method. This method relies on the continuous interpolation function, power function, where the base variable represents a pseudo density at each point of domain. For proper exponent values, the SIMP method reduces intermediate densities, since values other than 0 or 1 usually does not have a physical meaning for the problem. Several extension of the SIMP method were proposed for the multi-material case. The one that we explore here is the ordered SIMP method, that has the advantage of not being based on the addition of variables to represent material selection, so the computational cost is independent of the number of materials considered. Although the number of variables is not increased by this algorithm, the optimization subproblems that are generated at each iteration cannot be solved by methods that rely on second derivatives, due to the cost of calculating the second derivatives. To overcome this, we apply a globally convergent version of the sequential linear programming method, which solves a linear approximation sequence of optimization problems.Keywords: globally convergence, multi-material design ordered simp, sequential linear programming, topology optimization
Procedia PDF Downloads 316