Search results for: crude oil environments
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 2626

Search results for: crude oil environments

916 Colors and Interiority - A Study on the Relationship of Colors and Interior Spaces

Authors: Mahwish Ghulam Rasool

Abstract:

The design of a space is a complex process that involves multiple stages, from conceptualization, identifying design problems to understanding the context, materiality, and functionality of the space. Out of all the design elements, color is one of the most dominant and expressive factors that affect the spatial dynamics of the interior space. Color affects aesthetic comfort in space and has a lasting impact on human perception and psychology. Using color as a tool for creating spatial experiences is a new paradigm. Color semantics in spaces are not only used for surface treatment or aesthetics, but it also has more powerful functional characteristics. As interior spaces are evolving and becoming experiential with each decade, designers are looking for new processes to enhance the spatial and experiential quality of interior spaces. The relationship between color and interior typologies is a relatively new paradigm. This paper discusses the role of colors in interior spaces from various perspectives, exploring their impact on the formation of interior typologies and the use of colors in space design. The paper analyzes interior typologies worldwide, from residential to commercial interior spaces, where color semantics plays a prominent role in the design. The paper also emphasizes the design process and the creation of design language, unveiling the possibilities of applying colors in interior spaces that can be in harmony with the building context, space functionality, or in opposition to the existing building envelope or environment. The paper aims to contribute to the field of interior design education and practices. By using experimental and various research methodologies for investigation, it aims to fill the gap in the literature regarding color semantics and the relationship between interior typologies.

Keywords: color psychology, color semantics, interior environments, interior typologies

Procedia PDF Downloads 74
915 Ear Protectors and Their Action in Protecting Hearing System of Workers against Occupational Noise

Authors: F. Forouharmajd, S. Pourabdian, N. Ziayi Ghahnavieh

Abstract:

For many years, the ear protectors have been used to preventing the audio and non-audio effects of received noise from occupation environments. Despite performing hearing protection programs, there are many people which still suffer from noise-induced hearing loss. This study was conducted with the aim of determination of human hearing system response to received noise and the effectiveness of ear protectors on preventing of noise-induced hearing loss. Sound pressure microphones were placed in a simulated ear canal. The severity of noise measured inside and outside of ear canal. The noise reduction values due to installing ear protectors were calculated in the octave band frequencies and LabVIEW programmer. The results of noise measurement inside and outside of ear canal showed a different in received sound levels by ear canal. The effectiveness of ear protectors has been considerably reduced for the low frequency limits. A change in resonance frequency also was observed after using ear protectors. The study indicated the ear canal structure may affect the received noise and it may lead a difference between the received sound from the measured sound by a sound level meter, and hearing system. It means the human hearing system may probably respond different from a sound level meter. Hearing protectors’ efficiency declines by increasing the noise levels, and thus, they are not suitable to protect workers against industrial noise particularly low frequency noise. Hearing protectors may be solely a reason to damaging of hearing system in a special frequency via changing of human hearing system acoustical structure. We need developing the subjective method of hearing protectors testing, because their evaluation is not designed based on industrial noise or in the field.

Keywords: ear protector, hearing system, occupational noise, workers

Procedia PDF Downloads 158
914 Compact LWIR Borescope Sensor for Surface Temperature of Engine Components

Authors: Andy Zhang, Awnik Roy, Trevor B. Chen, Bibik Oleksandr, Subodh Adhikari, Paul S. Hsu

Abstract:

The durability of a combustor in gas-turbine enginesrequiresa good control of its component temperatures. Since the temperature of combustion gases frequently exceeds the melting point of the combustion liner walls, an efficient air-cooling system is significantly important to elongatethe lifetime of liner walls. To determine the effectiveness of the air-cooling system, accurate 2D surface temperature measurement of combustor liner walls is crucial for advanced engine development. Traditional diagnostic techniques for temperature measurement, such as thermocouples, thermal wall paints, pyrometry, and phosphors, have shown disadvantages, including being intrusive and affecting local flame/flow dynamics, potential flame quenching, and physical damages to instrumentation due to harsh environments inside the combustor and strong optical interference from strong combustion emission in UV-Mid IR wavelength. To overcome these drawbacks, a compact and small borescope long-wave-infrared (LWIR) sensor is developed to achieve two-dimensional high-spatial resolution, high-fidelity thermal imaging of 2D surface temperature in gas-turbine engines, providing the desired engine component temperature distribution. The compactLWIRborescope sensor makes it feasible to promote the durability of combustor in gas-turbine engines.

Keywords: borescope, engine, long-wave-infrared, sensor

Procedia PDF Downloads 118
913 Proximate Composition, Minerals and Sensory Attributes of Cake, Cookies, Cracker, and Chin-Chin Prepared from Cassava-Gari Residue Flour

Authors: Alice Nwanyioma Ohuoba, Rose Erdoo Kukwa, Ukpabi Joseph Ukpabi

Abstract:

Cassava root (Manihot esculenta) is one of the important carbohydrates containing crops in Nigeria. It is a staple food, mostly in the southern part of the country, and a source of income to farmers and processors. Cassava gari processing methods result to residue fiber (solid waste) from the sieving operation, these residue fibers ( solid wastes) can be dried and milled into flour and used to prepare cakes, cookies, crackers and chin-chin instead of being thrown away mostly on farmland or near the residential area. Flour for baking or frying may contain carbohydrates and protein (wheat flour) or rich in only carbohydrates (cassava flour). Cake, cookies, crackers, and chin-chin were prepared using the residue flour obtained from the residue fiber of cassava variety NR87184 roots, processed into gari. This study is aimed at evaluating the proximate composition, mineral content and sensory attributes of these selected snacks produced. The proximate composition results obtained showed that crackers had the lowest value in moisture (2.3390%) and fat (1.7130%), but highest in carbohydrates (85.2310%). Amongst the food products, cakes recorded the highest value in protein (8.0910%). Crude fibre values ranges from 2.5265% (cookies) to 3.4165% (crackers). The result of the mineral contents showed cookies ranking the highest in Phosphorus (65.8535 ppm) and Iron (0.1150 mg/L), Calcium (1.3800mg/L) and Potassium (7.2850 mg/L) contents, while chin-chin and crackers were lowest in Sodium ( 2.7000 mg/L). The food products were also subjected to sensory attributes evaluation by thirty member panelists using 9-hedonic scale which ranged from 1 ( dislike extremely) to 9 (like extremely). The means score obtained shows all the food products having above 7.00 (above “like moderately”). This study has shown that food products that may be functional or nutraceuticals could be prepared from the residue flour. There is a call for the use of gluten-free flour in baking due to ciliac disease and other allergic causes by gluten. Therefore local carbohydrates food crops like cassava residue flour that are gluten-free, could be the solution. In addition, this could aid cassava gari processing waste management thereby reducing post-harvest losses of cassava root.

Keywords: allergy, flour, food-products, gluten-free

Procedia PDF Downloads 142
912 Effect of Wavy Leading-Edges on Wings in Different Planetary Atmospheres

Authors: Vatasta Koul, Ayush Gupta, Vaibhav Sharma, Rajesh Yadav

Abstract:

Today we are unmarking the secrets of the universe by exploring different stars and planets and most of the space exploration is done by unmanned space robots. In addition to our planet Earth, there are pieces of evidence that show other astronomical objects in our solar system such as Venus, Mars, Saturn’s moon Titan and Uranus support the flight of fixed wing air vehicles. In this paper, we take forward the concept of presence of large rounded tubercles along the leading edge of a wing and use it as a passive flow control device that will help in improving its aerodynamic performance and maneuverability. Furthermore, in this research, aerodynamic measurements and performance analysis of wavy leading tubercles on the fixed wings at 5-degree angle of attack are carried out after determination of the flow conditions on the selected planetary bodies. Wavelength and amplitude for the sinusoidal modifications on the leading edge are analyzed and simulations are carried out for three-dimensional NACA 0012 airfoil maintaining unity AR (Aspect Ratio). Tubercles have consistently demonstrated the ability to delay and decrease the severity of stall as per the studies were done in the Earth’s atmosphere. Implementing the same design on the leading edges of Micro-Air Vehicles (MAVs) and UAVs could make these aircrafts more stable over a greater range of angles of attack in different planetary environments of our solar system.

Keywords: amplitude, NACA0012, tubercles, unmanned space robots

Procedia PDF Downloads 134
911 Effect of Rural Entrepreneurship in Rural Development in Nigeria: A Study of Selected Entrepreneurs in Ikwuano Local Government Area, Abia State, Nigeria

Authors: Ifeanyi Charles Otuokere, Victoria Nneoma Nnochiri

Abstract:

Entrepreneurship generally and specifically within the rural communities in Nigeria is a fast means of bringing development within the communities. This is made possible by utmost maximization and management of available local resources to develop rural areas through good management of these local resources. This study anchors on the rural development paradigm and the integrated rural development theories to understudy the knowledge of rural entrepreneurs on rural economic development. The research study made use of surveys and descriptive analysis. The assessable population for the study, which was randomly selected, is 100 rural entrepreneurs from ten rural communities within the Ikwuano Local Government Area of Abia State. The study made use of both primary and secondary as a source of data collection with much emphasis on a primary source, although secondary data such as journals, textbooks electronic sources were also utilised. A carefully structured questionnaire drafted to extract raw data was administered to selected entrepreneurs. The findings of the study showed that developments within rural communities can only be achieved through rural entrepreneurship. This is evidenced in increased output, job creation, and most importantly, reduction of rural to urban migration, among other things. Recommendations were also made based on these findings; the researchers recommended that infrastructural developments should be made available in the rural communities and government policies should create enabling environments along with other assistance to help these rural entrepreneurs achieve their sole aim.

Keywords: economic developments, rural communities, rural development, rural entrepreneurship

Procedia PDF Downloads 215
910 Adsorption and Transformation of Lead in Coimbatore Urban Soils

Authors: K. Sivasubramanin, S. Mahimairaja, S. Pavithrapriya

Abstract:

Heavy metal pollution originating from industrial wastes is becoming a serious problem in many urban environments. These heavy metals, if not properly managed, could enter into the food chain and cause a serious health hazards in animals and humans. Industrial wastes, sewage sludge, and automobile emissions also contribute to heavy metal like Pb pollution in the urban environment. However, information is scarce on the heavy metal pollution in Coimbatore urban environment. Therefore, the current study was carried out to examine the extent of lead pollution in Coimbatore urban environment the maximum Pb concentration in Coimbatore urban environment was found in ukkadam, whose concentration in soils 352 mg kg-1. In many places, the Pb concentration was found exceeded the permissible limit of 100 mg kg-1. In laboratory, closed incubation experiment showed that the concentration of different species of Pb viz., water soluble Pb(H2O-Pb), exchangeable Pb(KNO3-Pb), organic-Pb(NaOH-Pb), and organic plus metal (Fe & Al) oxides bound-Pb(Na2 EDTA-Pb) was found significantly increased during the 15 days incubation, mainly due to biotransformation processes. Both the moisture content of soil and ambient temperature exerted a profound influence on the transformation of Pb. The results of a batch experiment has shown that the sorption data was adequately described by the Freundlich equation as indicated by the high correlation coefficients (R2= 0.64) than the Langmuir equation (R2 = 0.33). A maximum of 86 mg of Pb was found adsorbed per kilogram of soil. Consistently, a soil column experiment result had shown that only a small amount of Pb( < 1.0 µg g-1 soil) alone was found leached from the soil. This might be due to greater potential of the soil towards Pb adsorption.

Keywords: lead pollution, adsorption, transformation, heavy metal pollution

Procedia PDF Downloads 315
909 High-Temperature Behavior of Boiler Steel by Friction Stir Processing

Authors: Supreet Singh, Manpreet Kaur, Manoj Kumar

Abstract:

High temperature corrosion is an imperative material degradation method experienced in thermal power plants and other energy generation sectors. Metallic materials such as ferritic steels have special properties such as easy fabrication and machinibilty, low cost, but a serious drawback of these materials is the worsening in properties initiating from the interaction with the environments. The metallic materials do not endure higher temperatures for extensive period of time because of their poor corrosion resistance. Friction Stir Processing (FSP), has emerged as the potent surface modification means and control of microstructure in thermo mechanically heat affecting zones of various metal alloys. In the current research work, FSP was done on the boiler tube of SA 210 Grade A1 material which is regularly used by thermal power plants. The strengthening of SA210 Grade A1 boiler steel through microstructural refinement by Friction Stir Processing (FSP) and analyze the effect of the same on high temperature corrosion behavior. The high temperature corrosion performance of the unprocessed and the FSPed specimens were evaluated in the laboratory using molten salt environment of Na₂SO₄-82%Fe₂(SO₄). The unprocessed and FSPed low carbon steel Gr A1 evaluation was done in terms of microstructure, corrosion resistance, mechanical properties like hardness- tensile. The in-depth characterization was done by EBSD, SEM/EDS and X-ray mapping analyses with an aim to propose the mechanism behind high temperature corrosion behavior of the FSPed steel.

Keywords: boiler steel, characterization, corrosion, EBSD/SEM/EDS/XRD, friction stir processing

Procedia PDF Downloads 226
908 Time and Cost Prediction Models for Language Classification Over a Large Corpus on Spark

Authors: Jairson Barbosa Rodrigues, Paulo Romero Martins Maciel, Germano Crispim Vasconcelos

Abstract:

This paper presents an investigation of the performance impacts regarding the variation of five factors (input data size, node number, cores, memory, and disks) when applying a distributed implementation of Naïve Bayes for text classification of a large Corpus on the Spark big data processing framework. Problem: The algorithm's performance depends on multiple factors, and knowing before-hand the effects of each factor becomes especially critical as hardware is priced by time slice in cloud environments. Objectives: To explain the functional relationship between factors and performance and to develop linear predictor models for time and cost. Methods: the solid statistical principles of Design of Experiments (DoE), particularly the randomized two-level fractional factorial design with replications. This research involved 48 real clusters with different hardware arrangements. The metrics were analyzed using linear models for screening, ranking, and measurement of each factor's impact. Results: Our findings include prediction models and show some non-intuitive results about the small influence of cores and the neutrality of memory and disks on total execution time, and the non-significant impact of data input scale on costs, although notably impacts the execution time.

Keywords: big data, design of experiments, distributed machine learning, natural language processing, spark

Procedia PDF Downloads 101
907 In vitro Study of Inflammatory Gene Expression Suppression of Strawberry and Blackberry Extracts

Authors: Franco Van De Velde, Debora Esposito, Maria E. Pirovani, Mary A. Lila

Abstract:

The physiology of various inflammatory diseases is a complex process mediated by inflammatory and immune cells such as macrophages and monocytes. Chronic inflammation, as observed in many cardiovascular and autoimmune disorders, occurs when the low-grade inflammatory response fails to resolve with time. Because of the complexity of the chronic inflammatory disease, major efforts have focused on identifying novel anti-inflammatory agents and dietary regimes that prevent the pro-inflammatory process at the early stage of gene expression of key pro-inflammatory mediators and cytokines. The ability of the extracts of three blackberry cultivars (‘Jumbo’, ‘Black Satin’ and ‘Dirksen’), and one strawberry cultivar (‘Camarosa’) to inhibit four well-known genetic biomarkers of inflammation: inducible nitric oxide synthase (iNOS), cyclooxynase-2 (Cox-2), interleukin-1β (IL-1β) and interleukin-6 (IL-6) in an in vitro lipopolysaccharide-stimulated murine RAW 264.7 macrophage model were investigated. Moreover, the effect of latter extracts on the intracellular reactive oxygen species (ROS) and nitric oxide (NO) production was assessed. Assay was conducted with 50 µg/mL crude extract concentration, an amount that is easily achievable in the gastrointestinal tract after berries consumption. The mRNA expression levels of Cox-2 and IL-6 were reduced consistently (more than 30%) by extracts of ‘Jumbo’ and ‘Black Satin’ blackberries. Strawberry extracts showed high reduction in mRNA expression levels of IL-6 (more than 65%) and exhibited moderate reduction in mRNA expression of Cox-2 (more than 35%). The latter behavior mirrors the intracellular ROS production of the LPS stimulated RAW 264.7 macrophages after the treatment with blackberry ‘Black Satin’ and ‘Jumbo’, and strawberry ‘Camarosa’ extracts, suggesting that phytochemicals from these fruits may play a role in the health maintenance by reducing oxidative stress. On the other hand, effective inhibition in the gene expression of IL-1β and iNOS was not observed by any of blackberry and strawberry extracts. However, suppression in the NO production in the activated macrophages among 5–25% was observed by ‘Jumbo’ and ‘Black Satin’ blackberry extracts and ‘Camarosa’ strawberry extracts, suggesting a higher NO suppression property by phytochemicals of these fruits. All these results suggest the potential beneficial effects of studied berries as functional foods with antioxidant and anti-inflammatory roles. Moreover, the underlying role of phytochemicals from these fruits in the protection of inflammatory process will deserve to be further explored.

Keywords: cyclooxygenase-2, functional foods, interleukin-6, reactive oxygen species

Procedia PDF Downloads 222
906 Physical, Chemical and Mechanical Properties of Different Varieties of Jatropha curcas Cultivated in Pakistan

Authors: Mehmood Ali, Attaullah Khan, Md. Abul Kalam

Abstract:

Petroleum crude oil reserves are going to deplete in future due to the consumption of fossil fuels in transportation and energy generating sector. Thus, increasing the fossil fuel prices and also causing environmental degradation issues such as climate change and global warming due to air pollution. Therefore, to tackle these issues the environmentally friendly fuels are the potential substitute with lower emissions of toxic gases. A non-edible vegetable oilseed crop, Jatropha curcas, from different origins such as Malaysia, Thailand and India were cultivated in Pakistan. The harvested seeds physical, chemical and mechanical properties were measured, having an influence on the post-harvesting machines design parameters for dehulling, storing bins, drying, oil extraction from seeds with a screw expeller and in-situ transesterification reaction to produce biodiesel fuel. The seed variety from Thailand was found better in comparison of its properties with other varieties from Malaysia and India. The seed yield from these three varieties i.e. Malaysia, Thailand and India were 829, 943 and 735 kg/ acre/ year respectively. While the oil extraction yield from Thailand variety seed was found higher (i.e. 32.61 % by wt.) as compared to other two varieties from Malaysia and India were 27.96 and 24.96 % by wt respectively. The physical properties investigated showed the geometric mean diameter of seeds from three varieties Malaysia, Thailand and India were 11.350, 10.505 and 11.324 mm, while the sphericity of seeds were found 0.656, 0.664 and 0.655. The bulk densities of the powdered seeds from three varieties Malaysia, Thailand and India, were found as 0.9697, 0.9932 and 0.9601 g/cm³ and % passing was obtained with sieve test were 78.7, 87.1 and 79.3 respectively. The densities of the extracted oil from three varieties Malaysia, Thailand and India were found 0.902, 0.898 and 0.902 g/ mL with corresponding kinematic viscosities 54.50, 49.18 and 48.16 mm2/sec respectively. The higher heating values (HHV) of extracted oil from Malaysia, Thailand and India seed varieties were measured as 40.29, 36.41 and 34.27 MJ/ kg, while the HHV of de-oiled cake from these varieties were 21.23, 20.78 and 17.31 MJ/kg respectively. The de-oiled cake can be used as compost with nutrients and carbon content to enhance soil fertility to grow future Jatropha curcas oil seed crops and also can be used as a fuel for heating and cooking purpose. Moreover, the mechanical parameter micro Vickers hardness of Malaysia seed was found lowest 16.30 HV measured with seed in a horizontal position to the loading in comparison to other two varieties as 25.2 and 18.7 HV from Thailand and India respectively. The fatty acid composition of three varieties of seed oil showed the presence of C8-C22, required to produce good quality biodiesel fuel. In terms of physicochemical properties of seeds and its extracted oil, the variety from Thailand was found better as compared to the other two varieties.

Keywords: biodiesel, Jatropha curcas, mechanical property, physico-chemical properties

Procedia PDF Downloads 126
905 Public Policy for Quality School Lunch Development in Thailand

Authors: W. Kongnoo, J. Loysongkroa, S. Chotivichien, N. Viriyautsahakul, N. Saiwongse

Abstract:

Obesity, stunting and wasting problems among Thai school-aged children are increasing due to inappropriate food consumption behavior and poor environments for desirable nutritional behavior. Because of a low school lunch budget of only 0.40 USD per person per day, food quality is not up to nutritional standards. Therefore, the Health Department with the Education Ministry and the Thai Health Promotion Foundation have developed a quality school lunch project during 2009–2013. The program objectives were development and management of public policy to increase school lunch budget. The methods used a healthy public policy motivation process and movement in 241 local administrative organizations and 538 schools. The problem and solution research was organized to study school food and nutrition management, create a best practice policy mobilization model and hold a public hearing to motivate an increase of school meal funding. The results showed that local public policy has been motivated during 2009-2011 to increase school meal budget using local budgets. School children with best food consumption behavior and exercise increased from 13.2% in 2009 to 51.6% in 2013 and stunting decreased from 6.0% in 2009 to 4.7% in 2013. As the result of national policy motivation (2012-2013), the cabinet meeting on October 22, 2013 has approved an increase of school lunch budget from 0.40 USD to 0.62 USD per person per day. Thus, 5,800,469 school children nationwide have benefited from the budget increase.

Keywords: public policy, quality school lunch, Thailand, obesity

Procedia PDF Downloads 335
904 Development of Latent Fingerprints on Non-Porous Surfaces Recovered from Fresh and Sea Water

Authors: A. Somaya Madkour, B. Abeer sheta, C. Fatma Badr El Dine, D. Yasser Elwakeel, E. Nermine AbdAllah

Abstract:

Criminal offenders have a fundamental goal not to leave any traces at the crime scene. Some may suppose that items recovered underwater will have no forensic value, therefore, they try to destroy the traces by throwing items in water. These traces are subjected to the destructive environmental effects. This can represent a challenge for Forensic experts investigating finger marks. Accordingly, the present study was conducted to determine the optimal method for latent fingerprints development on non-porous surfaces submerged in aquatic environments at different time interval. The two factors analyzed in this study were the nature of aquatic environment and length of submerged time. In addition, the quality of developed finger marks depending on the used method was also assessed. Therefore, latent fingerprints were deposited on metallic, plastic and glass objects and submerged in fresh or sea water for one, two, and ten days. After recovery, the items were subjected to cyanoacrylate fuming, black powder and small particle reagent processing and the prints were examined. Each print was evaluated according to fingerprint quality assessment scale. The present study demonstrated that the duration of submersion affects the quality of finger marks; the longer the duration, the worse the quality.The best results of visualization were achieved using cyanoacrylate either in fresh or sea water. This study has also revealed that the exposure to sea water had more destructive influence on the quality of detected finger marks.

Keywords: fingerprints, fresh water, sea, non-porous

Procedia PDF Downloads 441
903 Public Service Ethics in Public Administration: An Empirical Investigation

Authors: Kalsoom Sumra

Abstract:

The increasing concern of public sector reforms brings new challenges to public service ethics in developing countries not only at central level but also at local level. This paper aims to identify perceptions on public service ethics of public officials and examines more generally the understanding of public servants in Pakistan towards public service ethics in local public organizations. The study uses an independently administered structured questionnaire to collect data to know the extent of the recognition of public service ethics in local organizations. A total of 150 completed questionnaires are analyzed received from public servants working at the local level in Pakistan. The analysis explores how traditional, social patterns and cultural ethics can provide us with a rounded picture of the main antecedents, moderators of public service ethics in Pakistan. Moreover, the findings of this study contribute in association of public service ethics which are crucial in ongoing political and administrative culture of Pakistan, the most crucial core for public organizational ethical climate. This study also has numerous implications for local public administration and it highlights the importance of expanding research agenda on public service ethics in developing settings with challenging institutional contexts with imperfect training and operating environments. This study may well be particularly important for practice of public service ethics in developing countries in public administration. To the best of author’s knowledge, this study is the first of its kind to provide an initial step in practical implications to emphasize relevant public service ethics in public administration in developing transparent and accountable organization.

Keywords: public service ethics, accountability and transparency, public service reforms, public administration, organizational ethical climate

Procedia PDF Downloads 332
902 Self-Efficacy in Online Vocal Learning: Current Situation, Influencing Factors and Optimization Strategies

Authors: Tianyou Wang

Abstract:

Students' own intrinsic motivation is the main source of energy for learning activities, and their self-efficacy becomes a key factor affecting the learning effect. In today's increasingly common situation of online vocal music teaching, virtualized teaching scenarios have brought a considerable impact on students' personal efficacy. Since personal efficacy is the result of the interaction between environmental factors and subject characteristics, an empirical study was conducted to investigate the changes in students' self-efficacy, influencing factors, and characteristics in online vocal teaching scenarios based on the three dimensions of teachers, students, and technology. One hundred valid questionnaires were studied through a quantitative survey. The results showed that students' personal efficacy was significantly lower in online learning environments compared to offline vocal teaching and showed significant differences due to factors such as gender and class type; students' self-efficacy in online vocal teaching was significantly affected by factors such as technological environment, teaching style, and information technology ability. Based on the results of the study, it is recommended to pay attention to inquiry and practice in the teaching design, use singing projects as the teaching organization, grasp the learning process with the orientation of problem-solving, push the applicable vocal music teaching resources in time, lead students to explore and refine the problems and push students to learn independently according to the goals and plans.

Keywords: vocal pedagogy, self-efficacy, online learning, intrinsic motivation, information technology

Procedia PDF Downloads 42
901 Geochemical Study of Natural Bitumen, Condensate and Gas Seeps from Sousse Area, Central Tunisia

Authors: Belhaj Mohamed, M. Saidi, N. Boucherab, N. Ouertani, I. Bouazizi, M. Ben Jrad

Abstract:

Natural hydrocarbon seepage has helped petroleum exploration as a direct indicator of gas and/or oil subsurface accumulations. Surface macro-seeps are generally an indication of a fault in an active Petroleum Seepage System belonging to a Total Petroleum System. This paper describes a case study in which multiple analytical techniques were used to identify and characterize trace petroleum-related hydrocarbons and other volatile organic compounds in groundwater samples collected from Sousse aquifer (Central Tunisia). The analytical techniques used for analyses of water samples included gas chromatography-mass spectrometry (GC-MS), capillary GC with flame-ionization detection, Compund Specific Isotope Analysis, Rock Eval Pyrolysis. The objective of the study was to confirm the presence of gasoline and other petroleum products or other volatile organic pollutants in those samples in order to assess the respective implication of each of the potentially responsible parties to the contamination of the aquifer. In addition, the degree of contamination at different depths in the aquifer was also of interest. The oil and gas seeps have been investigated using biomarker and stable carbon isotope analyses to perform oil-oil and oil-source rock correlations. The seepage gases are characterized by high CH4 content, very low δ13CCH4 values (-71,9 ‰) and high C1/C1–5 ratios (0.95–1.0), light deuterium–hydrogen isotope ratios (-198 ‰) and light δ13CC2 and δ13CCO2 values (-23,8‰ and-23,8‰ respectively) indicating a thermogenic origin with the contribution of the biogenic gas. An organic geochemistry study was carried out on the more ten oil seep samples. This study includes light hydrocarbon and biomarkers analyses (hopanes, steranes, n-alkanes, acyclic isoprenoids, and aromatic steroids) using GC and GC-MS. The studied samples show at least two distinct families, suggesting two different types of crude oil origins: the first oil seeps appears to be highly mature, showing evidence of chemical and/or biological degradation and was derived from a clay-rich source rock deposited in suboxic conditions. It has been sourced mainly by the lower Fahdene (Albian) source rocks. The second oil seeps was derived from a carbonate-rich source rock deposited in anoxic conditions, well correlated with the Bahloul (Cenomanian-Turonian) source rock.

Keywords: biomarkers, oil and gas seeps, organic geochemistry, source rock

Procedia PDF Downloads 432
900 Statistical Relation of Abiotic Factors to Methane Emissions in Arctic Environment, Alaksa

Authors: Vasudha Chaturvedi, Mauro Guglielmin, Nicoletta Canone, Chiara Casiraghi, Francesco Griforni, Lorenzo Tonin, Silvia Piconne, Ilaria Bonfati, Filippo Caccia, Stefano Ponti

Abstract:

The study explores the complex interplay between abiotic factors and methane emissions in Arctic environments. It highlights the challenges in understanding these relationships across different vegetation communities and seasons, considering the influence of multiple drivers. In the spring and early winter of 2023, we investigated net methane fluxes and 55 environmental parameters at three distinct sites in Alaska representing wet tundra, tussock, and dry heath using closed chamber techniques. Each site underwent three measurement cycles over consecutive days. Our findings reveal that tussock exhibited the highest methane emissions (ranging from 17 to 44 nmol m-2 s-1), followed by wet tundra (3 to 38 nmol m-2 s-1), while the dry heath consistently consumed methane across all seasons (-1.2 nmol m-2 s-1). Diurnal flux patterns at tussock sites peaked in the afternoon towards beginning of winter season, with correlations observed between fluxes and water content at 20 cm depth across all sites, and additionally with ground surface temperature (GST) temperature and water content at 0–60 cm depth at one site. Wet sites displayed higher correlations with GST up to 60 cm depth. These findings underscore the importance of considering site-specific dynamics and multiple environmental variables in understanding methane emissions from Arctic ecosystems.

Keywords: climate change, cryosphere, methane fluxes, soil, ground temperature

Procedia PDF Downloads 25
899 In Vitro Antimycoplasmal Activity of Peganum harmala on Mycoplasma hominis Tunisian Strains

Authors: Nadine khadraoui, Rym Essid, Olfa Tabbene, Imen Chniba, Safa Boujemaa, Selim Jallouli, Nadia Fares, Behija Mlik, Boutheina Ben Abdelmoumen Mardassi

Abstract:

Background and aim: Mycoplasma hominis is an opportunistic pathogen that can cause various gynecological infections such cervicitis, infertility, and, less frequently, extra-genital infections. Previous studies on the antimicrobial susceptibility of Mycoplasma hominis Tunisian strains have highlighted a significant resistance, even multi-resistance, to the most used antibiotic in the therapy of consequential infections. To address this concern, the present study aimed for the alternative of phytotherapy. Peganum harmala seed extract was tested as an antibacterial agent against multidrug-resistant M.hominis clinical strains. Material and Methods: Peganum harmala plant was collected from Ain Sebaa, Tabarka, North West region of Tunisia in April 2018, air-dried, grounded and extracted by different solvents.The crude methanolic extract was further partitioned with n-HEX, DCM, EtOAC and n-BuOl. Antibacterial activity was evaluated against M. hominis ATCC 23114 and 20 M. hominis clinical strains.The antimycoplasmal activity was tested by the microdilution method, and MIC values were determined. Phytochemical analysis and hemolytic activity on human erythrocytes were also performed. The active fraction was then subjected to purification, and the chemical identification of the active compound was investigated. Results: Among the tested fractions, the n-BuOH extract was the most active fraction since it exhibited an inhibitory effect against M. hominis ATCC 23114 and 80% of the tested clinical strains with MIC between 125 and 1000 µg/ml. The phytochemical analysis of the n-BuOH revealed its metabolic abundance in polyphenols, flavonoids and condensed tannin with levels of 257.37 mg AGE/g, 172.27 mg EC/g and 58.27 mg EC/g, respectively. In addition, P. harmala n-BuOH extract exhibited potent bactericidal activity against all M. hominis isolates with CMB values ranging between 125 and 4000 µg/ml. Further, the active fraction exhibited weak cytotoxicity effect at active concentrations when tested on human erythrocytes. The active compound was identified by gas chromatography–mass spectrometry as an indole alkaloid harmaline. Conclusion: In summary, Peganum harmala extract demonstrated an interesting anti-mycoplasmal activity against M. hominis Tunisian strains. Therefore, it could be considered as a potential candidate for the treatment of consequential infections. However, further studies are necessary to evaluate its mechanism of action in mycoplasmas.

Keywords: mycoplasma hominis, peganum harmala, antibioresistance, phytotherapy, phytochemical analysis

Procedia PDF Downloads 100
898 Identifying Business Opportunities Based on Patent and Trademark Portfolios: a Technology-Based Service Industry Case

Authors: Mingook Lee, Sungjoo Lee

Abstract:

As technology-based service industries grow drastically worldwide; companies are recognizing the importance of market preoccupancy and have made an effort to capture a large market to gain the upper hand. To this end, a focus on patents can be used to determine the properties of a technology, as well as to capture advantages in technical skills, in comparison with the firm’s competitors. However, technology-based services largely depend not only on their technological value but also their economic value, due to the recognized worth that is passed to a plurality of users. Thus, it is important to determine whether there are any competitors in the target areas and what services they provide in any field. Despite this importance, little effort has been made to systematically benchmark competitors in order to identify business opportunities. Thus, this study aims to not only identify each position of technology-centered service companies in complex market dynamics, but also to discover new business opportunities. For this, we try to consider both technology and market environments simultaneously by utilizing patent data as a representative proxy for technology and trademark dates as an index for a firm’s target goods and services. Theoretically, this is one of the earliest attempts to combine patent data and trademark data to analyze corporate strategies. In practice, the research results are expected to be used as a decision criterion to diagnose the economic value that companies can obtain by entering the market, as well as the technological value to be passed onto their customers. Thus, the proposed approach can be useful to support effective technology and business strategies in a firm.

Keywords: business opportunity, patent, Portfolio analysis, trademark

Procedia PDF Downloads 279
897 GA3C for Anomalous Radiation Source Detection

Authors: Chia-Yi Liu, Bo-Bin Xiao, Wen-Bin Lin, Hsiang-Ning Wu, Liang-Hsun Huang

Abstract:

In order to reduce the risk of radiation damage that personnel may suffer during operations in the radiation environment, the use of automated guided vehicles to assist or replace on-site personnel in the radiation environment has become a key technology and has become an important trend. In this paper, we demonstrate our proof of concept for autonomous self-learning radiation source searcher in an unknown environment without a map. The research uses GPU version of Asynchronous Advantage Actor-Critic network (GA3C) of deep reinforcement learning to search for radiation sources. The searcher network, based on GA3C architecture, has self-directed learned and improved how search the anomalous radiation source by training 1 million episodes under three simulation environments. In each episode of training, the radiation source position, the radiation source intensity, starting position, are all set randomly in one simulation environment. The input for searcher network is the fused data from a 2D laser scanner and a RGB-D camera as well as the value of the radiation detector. The output actions are the linear and angular velocities. The searcher network is trained in a simulation environment to accelerate the learning process. The well-performance searcher network is deployed to the real unmanned vehicle, Dashgo E2, which mounts LIDAR of YDLIDAR G4, RGB-D camera of Intel D455, and radiation detector made by Institute of Nuclear Energy Research. In the field experiment, the unmanned vehicle is enable to search out the radiation source of the 18.5MBq Na-22 by itself and avoid obstacles simultaneously without human interference.

Keywords: deep reinforcement learning, GA3C, source searching, source detection

Procedia PDF Downloads 99
896 Current Status and Future Trends of Mechanized Fruit Thinning Devices and Sensor Technology

Authors: Marco Lopes, Pedro D. Gaspar, Maria P. Simões

Abstract:

This paper reviews the different concepts that have been investigated concerning the mechanization of fruit thinning as well as multiple working principles and solutions that have been developed for feature extraction of horticultural products, both in the field and industrial environments. The research should be committed towards selective methods, which inevitably need to incorporate some kinds of sensor technology. Computer vision often comes out as an obvious solution for unstructured detection problems, although leaves despite the chosen point of view frequently occlude fruits. Further research on non-traditional sensors that are capable of object differentiation is needed. Ultrasonic and Near Infrared (NIR) technologies have been investigated for applications related to horticultural produce and show a potential to satisfy this need while simultaneously providing spatial information as time of flight sensors. Light Detection and Ranging (LIDAR) technology also shows a huge potential but it implies much greater costs and the related equipment is usually much larger, making it less suitable for portable devices, which may serve a purpose on smaller unstructured orchards. Portable devices may serve a purpose on these types of orchards. In what concerns sensor methods, on-tree fruit detection, major challenge is to overcome the problem of fruits’ occlusion by leaves and branches. Hence, nontraditional sensors capable of providing some type of differentiation should be investigated.

Keywords: fruit thinning, horticultural field, portable devices, sensor technologies

Procedia PDF Downloads 129
895 Replica-Exchange Metadynamics Simulations of G-Quadruplex DNA Structures Under Substitution of K+ by Na+ Ions

Authors: Juan Antonio Mondragon Sanchez, Ruben Santamaria

Abstract:

The DNA G-quadruplex is a four-stranded DNA structure conformed by stacked planes of four base paired guanines (G-quartet). The guanine rich DNA sequences are present in many sites of genomic DNA and can potentially lead to the formation of G-quadruplexes, especially at the 3'-terminus of the human telomeric DNA with many TTAGGG repeats. The formation and stabilization of a G-quadruplex by small ligands at the telomeric region can inhibit the telomerase activity. In turn, the ligands can be used to regulate oncogene expression making the G-quadruplex an attractive target for anticancer therapy. Clearly, the G-quadruplex structured in the telomeric DNA is of fundamental importance for rational drug design. In this context, we investigate two G-quadruplex structures, the first follows from the sequence TTAGGG(TTAGGG)3TT (HUT1), and the second from AAAGGG(TTAGGG)3AA (HUT2), both in a K+ solution. We determine the free energy surfaces of the HUT1 and HUT2 structures and investigate their conformations using replica-exchange metadynamics simulations. The carbonyl-carbonyl distances belonging to different guanines residues are selected as the main collective variables to determine the free energy surfaces. The surfaces exhibit two main local minima, compatible with experiments on the conformational transformations of HUT1 and HUT2 under substitution of the K+ ions by the Na+ ions. The conformational transitions are not observed in short MD simulations without the use of the metadynamics approach. The results of this work should be of help to understand the formation and stability of human telomeric G-quadruplex in environments including the presence of K+ and Na+ ions.

Keywords: g-quadruplex, metadynamics, molecular dynamics, replica-exchange

Procedia PDF Downloads 333
894 A Scenario-Based Experiment Comparing Managerial and Front-Line Employee Apologies in Terms of Customers' Perceived Justice, Satisfaction, and Commitment

Authors: Ioana Dallinger, Vincent P. Magnini

Abstract:

Due to the many moving parts and high human component, mistakes and failures sometimes occur during transactions in service environments. Because a certain portion of such failures is unavoidable, many service providers constantly look for guidance regarding optimal ways by which they should manage failures and recoveries. Through the use of a scenario-based experiment, the findings of this study run counter to the empowerment approach (i.e. that frontline employees should be empowered to resolve failure situations on their own doing). Specifically, this study finds that customers’ perceptions of distributive, procedural, and interactional justice are significantly higher [p-values < .05] when a manager delivers an apology as opposed to the frontline provider. Moreover, customers’ satisfaction with the recovery and commitment to the firm are also significantly stronger [p-values < .05] when a manager apologizes. Interestingly, this study also empirically tests the effects of combined apologies of both the manager and employee and finds that the combined approach yields better results for customers’ interactional justice perceptions and for their satisfaction with recovery, but not for their distributive or procedural justice perceptions or consequent commitment to the firm. This study can serve a springboard for further research. For example, perceptions and attitudes regarding employee empowerment vary based upon country culture. Furthermore, there are likely a number of factors that can moderate the cause and effect relationship between a failure recovery and customers’ post-recovery perceptions [e.g. the severity of the failure].

Keywords: apology, empowerment, service failure recovery, service recovery

Procedia PDF Downloads 286
893 Comparative Fragility Analysis of Shallow Tunnels Subjected to Seismic and Blast Loads

Authors: Siti Khadijah Che Osmi, Mohammed Ahmad Syed

Abstract:

Underground structures are crucial components which required detailed analysis and design. Tunnels, for instance, are massively constructed as transportation infrastructures and utilities network especially in urban environments. Considering their prime importance to the economy and public safety that cannot be compromised, thus any instability to these tunnels will be highly detrimental to their performance. Recent experience suggests that tunnels become vulnerable during earthquakes and blast scenarios. However, a very limited amount of studies has been carried out to study and understanding the dynamic response and performance of underground tunnels under those unpredictable extreme hazards. In view of the importance of enhancing the resilience of these structures, the overall aims of the study are to evaluate probabilistic future performance of shallow tunnels subjected to seismic and blast loads by developing detailed fragility analysis. Critical non-linear time history numerical analyses using sophisticated finite element software Midas GTS NX have been presented about the current methods of analysis, taking into consideration of structural typology, ground motion and explosive characteristics, effect of soil conditions and other associated uncertainties on the tunnel integrity which may ultimately lead to the catastrophic failure of the structures. The proposed fragility curves for both extreme loadings are discussed and compared which provide significant information the performance of the tunnel under extreme hazards which may beneficial for future risk assessment and loss estimation.

Keywords: fragility analysis, seismic loads, shallow tunnels, blast loads

Procedia PDF Downloads 325
892 Xylanase Impact beyond Performance: A Prebiotic Approach in Laying Hens

Authors: Veerle Van Hoeck, Ingrid Somers, Dany Morisset

Abstract:

Anti-nutritional factors such as non-starch polysaccharides (NSP) are present in viscous cereals used to feed poultry. Therefore, exogenous carbohydrases are commonly added to monogastric feed to degrade these NSP. Our hypothesis is that xylanase not only improves laying hen performance and digestibility but also induces a significant shift in microbial composition within the intestinal tract and, thereby, can cause a prebiotic effect. In this context, a better understanding of whether and how the chicken gut flora can be modulated by xylanase is needed. To do so, in the herein laying hen study, the effects of dietary supplementation of xylanase on performance, digestibility, and cecal microbiome were evaluated. A total of 96 HiSex laying hens was used in this experiment (3 diets and 16 replicates of 2 hens). Xylanase was added to the diets at concentrations of 0, 45,000 (15 g/t XygestTM HT) and 90,000 U/kg (30 g/t Xygest HT). The diets were based on wheat (~55 %), soybean, and sunflower meal. The lowest dosage, 45,000 U/kg, significantly increased average egg weight and improved feed efficiency compared to the control treatment (p < 0.05). Egg quality parameters were significantly improved in the experiment in response to the xylanase addition. For example, during the last 28 days of the trial, the 45,000 U/kg and the 90,000 U/kg treatments exhibited an increase in Haugh units and albumin heights (p < 0.05). Compared with the control, organic matter digestibility and N retention were drastically improved in the 45,000 U/kg treatment group, which implies better nutrient digestibility at this lowest recommended dosage compared to the control (p < 0.05). Furthermore, gross energy and crude fat digestibility were improved significantly for birds fed 90,000 U/kg group compared to the control. Importantly, 16S rRNA gene analysis revealed that xylanase at 45,000 U/kg dosages can exert a prebiotic effect. This conclusion was drawn based on studying the sequence variation in the 16S rRNA gene in order to characterize diverse microbial communities of the cecal content. A significant increase in beneficial bacteria (Lactobacilli spp and Enterococcus casseliflavus) was documented when adding 45,000 U/kg xylanase to the diet of laying hens. In conclusion, dietary supplementation of xylanase, even at the lowest dose of (45,000 U/kg), significantly improved laying hen performance and digestibility. Furthermore, it is generally accepted that a proper bacterial balance between the number of beneficial bacteria and pathogenic bacteria in the intestine is vital for the host. It seems that the xylanase enzyme is able to modulate the laying hen microbiome beneficially and thus exerts a prebiotic effect. This microbiome plasticity in response to the xylanase provides an attractive target for stimulating intestinal health.

Keywords: laying hen, prebiotic, XygestTM HT, xylanase

Procedia PDF Downloads 115
891 Evaluation of Real-Time Background Subtraction Technique for Moving Object Detection Using Fast-Independent Component Analysis

Authors: Naoum Abderrahmane, Boumehed Meriem, Alshaqaqi Belal

Abstract:

Background subtraction algorithm is a larger used technique for detecting moving objects in video surveillance to extract the foreground objects from a reference background image. There are many challenges to test a good background subtraction algorithm, like changes in illumination, dynamic background such as swinging leaves, rain, snow, and the changes in the background, for example, moving and stopping of vehicles. In this paper, we propose an efficient and accurate background subtraction method for moving object detection in video surveillance. The main idea is to use a developed fast-independent component analysis (ICA) algorithm to separate background, noise, and foreground masks from an image sequence in practical environments. The fast-ICA algorithm is adapted and adjusted with a matrix calculation and searching for an optimum non-quadratic function to be faster and more robust. Moreover, in order to estimate the de-mixing matrix and the denoising de-mixing matrix parameters, we propose to convert all images to YCrCb color space, where the luma component Y (brightness of the color) gives suitable results. The proposed technique has been verified on the publicly available datasets CD net 2012 and CD net 2014, and experimental results show that our algorithm can detect competently and accurately moving objects in challenging conditions compared to other methods in the literature in terms of quantitative and qualitative evaluations with real-time frame rate.

Keywords: background subtraction, moving object detection, fast-ICA, de-mixing matrix

Procedia PDF Downloads 82
890 Instructional Immediacy Practices in Asynchronous Learning Environment: Tutors' Perspectives

Authors: Samar Alharbi, Yota Dimitriadi

Abstract:

With the exponential growth of information and communication technologies in higher education, new online teaching strategies have become increasingly important for student engagement and learning. In particular, some institutions depend solely on asynchronous e-learning to provide courses for their students. The major challenge facing these institutions is how to improve the quality of teaching and learning in their asynchronous tools. One of the most important methods that can help e-learner to enhance their social learning and social presence in asynchronous learning setting is immediacy. This study explores tutors perceptions of their instructional immediacy practices as part of their communication actions in online learning environments. It was used a mixed-methods design under the umbrella of pragmatic philosophical assumption. The participants included tutors at an educational institution in a Saudi university. The participants were selected with a purposive sampling approach and chose an institution that offered fully online courses to students. The findings of the quantitative data show the importance of teachers’ immediacy practices in an online text-based learning environment. The qualitative data contained three main themes: the tutors’ encouragement of student interaction; their promotion of class participation; and their addressing of the needs of the students. The findings from these mixed methods can provide teachers with insights into instructional designs and strategies that they can adopt in order to use e-immediacy in effective ways, thus improving their students’ online learning experiences.

Keywords: asynchronous e-learning, higher education, immediacy, tutor

Procedia PDF Downloads 189
889 Evaluation of Dry Matter Yield of Panicum maximum Intercropped with Pigeonpea and Sesbania Sesban

Authors: Misheck Musokwa, Paramu Mafongoya, Simon Lorentz

Abstract:

Seasonal shortages of fodder during the dry season is a major constraint to smallholder livestock farmers in South Africa. To mitigate the shortage of fodder, legume trees can be intercropped with pastures which can diversify the sources of feed and increase the amount of protein for grazing animals. The objective was to evaluate dry matter yield of Panicum maximum and land productivity under different fodder production systems during 2016/17-2017/18 seasons at Empangeni (28.6391° S and 31.9400° E). A randomized complete block design, replicated three times was used, the treatments were sole Panicum maximum, Panicum maximum + Sesbania sesban, Panicum maximum + pigeonpea, sole Sesbania sesban, Sole pigeonpea. Three months S.sesbania seedlings were transplanted whilst pigeonpea was direct seeded at spacing of 1m x 1m. P. maximum seeds were drilled at a respective rate of 7.5 kg/ha having an inter-row spacing of 0.25 m apart. In between rows of trees P. maximum seeds were drilled. The dry matter yield harvesting times were separated by six months’ timeframe. A 0.25 m² quadrant randomly placed on 3 points on the plot was used as sampling area during harvesting P. maximum. There was significant difference P < 0.05 across 3 harvests and total dry matter. P. maximum had higher dry matter yield as compared to both intercrops at first harvest and total. The second and third harvest had no significant difference with pigeonpea intercrop. The results was in this order for all 3 harvest: P. maximum (541.2c, 1209.3b and 1557b) kg ha¹ ≥ P. maximum + pigeonpea (157.2b, 926.7b and 1129b) kg ha¹ > P. maximum + S. sesban (36.3a, 282a and 555a) kg ha¹. Total accumulation of dry matter yield of P. maximum (3307c kg ha¹) > P. maximum + pigeonpea (2212 kg ha¹) ≥ P. maximum + S. sesban (874 kg ha¹). There was a significant difference (P< 0.05) on seed yield for trees. Pigeonpea (1240.3 kg ha¹) ≥ Pigeonpea + P. maximum (862.7 kg ha¹) > S.sesbania (391.9 kg ha¹) ≥ S.sesbania + P. maximum. The Land Equivalent Ratio (LER) was in the following order P. maximum + pigeonpea (1.37) > P. maximum + S. sesban (0.84) > Pigeonpea (0.59) ≥ S. Sesbania (0.57) > P. maximum (0.26). Results indicates that it is beneficial to have P. maximum intercropped with pigeonpea because of higher land productivity. Planting grass with pigeonpea was more beneficial than S. sesban with grass or sole cropping in terms of saving the shortage of arable land. P. maximum + pigeonpea saves a substantial (37%) land which can be subsequently be used for other crop production. Pigeonpea is recommended as an intercrop with P. maximum due to its higher LER and combined production of livestock feed, human food, and firewood. Panicum grass is low in crude protein though high in carbohydrates, there is a need for intercropping it with legume trees. A farmer who buys concentrates can reduce costs by combining P. maximum with pigeonpea this will provide a balanced diet at low cost.

Keywords: fodder, livestock, productivity, smallholder farmers

Procedia PDF Downloads 136
888 Grain Selection in Spiral Grain Selectors during Casting Single-Crystal Turbine Blades

Authors: M. Javahar, H. B. Dong

Abstract:

Single crystal components manufactured using Ni-base Superalloys are routinely used in the hot sections of aero engines and industrial gas turbines due to their outstanding high temperature strength, toughness and resistance to degradation in corrosive and oxidative environments. To control the quality of the single crystal turbine blades, particular attention has been paid to grain selection, which is used to obtain the single crystal morphology from a plethora of columnar grains. For this purpose, different designs of grain selectors are employed and the most common type is the spiral grain selector. A typical spiral grain selector includes a starter block and a spiral (helix) located above. It has been found that the grains with orientation well aligned to the thermal gradient survive in the starter block by competitive grain growth while the selection of the single crystal grain occurs in the spiral part. In the present study, 2D spiral selectors with different geometries were designed and produced using a state-of-the-art Bridgeman Directional Solidification casting furnace to investigate the competitive growth during grain selection in 2d grain selectors. The principal advantage of using a 2-D selector is to facilitate the wax injection process in investment casting by enabling significant degree of automation. The automation within the process can be derived by producing 2D grain selector wax patterns parts using a split die (metal mold model) coupled with wax injection stage. This will not only produce the part with high accuracy but also at an acceptable production rate.

Keywords: grain selector, single crystal, directional solidification, CMSX-4 superalloys, investment casting

Procedia PDF Downloads 569
887 Aircraft Components, Manufacturing and Design: Opportunities, Bottlenecks, and Challenges

Authors: Ionel Botef

Abstract:

Aerospace products operate in very aggressive environments characterized by high temperature, high pressure, large stresses on individual components, the presence of oxidizing and corroding atmosphere, as well as internally created or externally ingested particulate materials that induce erosion and impact damage. Consequently, during operation, the materials of individual components degrade. In addition, the impact of maintenance costs for both civil and military aircraft was estimated at least two to three times greater than initial purchase values, and this trend is expected to increase. As a result, for viable product realisation and maintenance, a spectrum of issues regarding novel processing technologies, innovation of new materials, performance, costs, and environmental impact must constantly be addressed. One of these technologies, namely the cold-gas dynamic-spray process has enabled a broad range of coatings and applications, including many that have not been previously possible or commercially practical, hence its potential for new aerospace applications. Therefore, the purpose of this paper is to summarise the state of the art of this technology alongside its theoretical and experimental studies, and explore how the cold-gas dynamic-spray process could be integrated within a framework that finally could lead to more efficient aircraft maintenance. Based on the paper's qualitative findings supported by authorities, evidence, and logic essentially it is argued that the cold-gas dynamic-spray manufacturing process should not be viewed in isolation, but should be viewed as a component of a broad framework that finally leads to more efficient aerospace operations.

Keywords: aerospace, aging aircraft, cold spray, materials

Procedia PDF Downloads 106