Search results for: hard disk

Authors: Mahdi Fakoor, Nabi Mehri Khansari, Ahmadreza Farokhi

Abstract:

Evaluation of mode II fracture toughness (KIIC) in composite materials is very hard problem to be solved, since it can be affected by many mechanisms of dissipation. Furthermore, non-linearity in its behavior can offer an extra difficulty to obtain accuracy in the results. Different reported values for KIIC in various references can prove the mentioned assertion. In this research, some solutions proposed based on the form of necessary corrections that should be executed on the common test fixtures. Due to the fact that the common test fixtures are not able to active toughening mechanisms in pure Mode II correctly, we have employed some structural modifications on common fixtures. Particularly, the Iosipescu test is used as start point. The tests are applied on graphite/epoxy; PMMA and Western White Pine Wood. Also, mixed mode I/II fracture limit curves are used to indicate the scattering in test results are really relevant to the creation of Fracture Process Zone (FPZ). In the present paper, shear load consideration applied at the predicted shear zone by considering some significant structural amendments that can active mode II toughening mechanisms. Indeed, the employed empirical method causes significant developing in repeatability and reproducibility as well. Moreover, a 3D Finite Element (FE) is performed for verification of the obtained results. Eventually, it is figured out that, a remarkable precision can be obtained in common test fixture in comparison with the previous one.

Keywords: FPZ, shear test fixture, mode II fracture toughness, composite material, FEM

Procedia PDF Downloads 361

Authors: Moon Byung Woo, Seok Chang-Sung, Koo Jae-Mean, Kim Sang-Young, Choi Jae Gu, Huh Nam-Su

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Recently, the occurrence of the earthquake has increased sharply and many of the casualties have occurred worldwide, due to the influence of earthquakes. Especially, the Fukushima nuclear power plant accident which was caused by the earthquake in 2011 has significantly increased the fear of people and the demand for the safety of the nuclear power plant. Thus, in order to prevent the earthquake accident at nuclear power plant, it is important to evaluate the fracture toughness considering the seismic loading rate. To obtain fracture toughness for the safety evaluation of nuclear power plant, it is desirable to perform experiments with a real scale pipe which is expensive and hard to perform. Therefore, many researchers have proposed various test specimens to replicate the fracture toughness of a real scale pipe. Since such specimens have several problems, the equivalent stress gradient (ESG) specimen has been recently suggested. In this study, in order to consider the effects of the dynamic loading speed on fracture toughness, the experiment was conducted by applying five different kinds of test speeds using an ESG specimen. In addition, after we performed the fracture toughness test under dynamic loading with different speeds using an ESG specimen and a standard specimen, we compared them with the test results under static loading.

Keywords: dynamic loading speed, fracture toughness, load-ratio-method, equivalent stress gradient (ESG) specimen

Procedia PDF Downloads 309

Authors: Martin Leroux, Sylvain Brisebois

Abstract:

Eating a meal is among the Activities of Daily Living, but it takes a lot of time and effort for people with physical or functional limitations. Dedicated technologies are cumbersome and not portable, while general-purpose assistive robots such as wheelchair-based manipulators are too hard to control for elaborate continuous motion like eating. Eating with such devices has not previously been automated, since there existed no description of a feeding motion for uncontrolled environments. In this paper, we introduce a feeding mode for assistive manipulators, including a mathematical description of trajectories for motions that are difficult to perform manually such as gathering and scooping food at a defined/desired pace. We implement these trajectories in a sequence of movements for a semi-automated feeding mode which can be controlled with a very simple 3-button interface, allowing the user to have control over the feeding pace. Finally, we demonstrate the feeding mode with a JACO robotic arm and compare the eating speed, measured in bites per minute of three eating methods: a healthy person eating unaided, a person with upper limb limitations or disability using JACO with manual control, and a person with limitations using JACO with the feeding mode. We found that the feeding mode allows eating about 5 bites per minute, which should be sufficient to eat a meal under 30min.

Keywords: assistive robotics, automated feeding, elderly care, trajectory design, human-robot interaction

Procedia PDF Downloads 162

Authors: Jie Chen, Chris Cheng, Kai Zhang

Abstract:

Polycrystalline diamond compact (PDC) cutters with a polycrystalline diamond (PCD) table supported by a cemented tungsten carbide substrate have been widely used for earth-drilling tools in the oil and gas industry. Both wear and impact resistances are key figure of merits of PDC cutters, and they are closely related to the microstructure of the PCD table. As oil and gas exploration enters deeper, harder, and more complex formations, plus increasing requirement of accelerated downhole drilling speed and drilling cost reduction, current PDC cutters face unprecedented challenges for maintaining a longer drilling life than ever. Excessive wear on uneven hard formations, spalling, chipping, and premature fracture due to impact loads are common failure modes of PDC cutters in the field. Tailoring microstructure of the PCD table is one of the effective approaches to improve the wear and impact resistances of PDC cutters, along with other factors such as cutter geometry and bit design. In this research, cross-sectional microstructure, fracture surface, wear surface, and elemental composition of PDC cutters were analyzed using scanning electron microscopy (SEM) with both backscattered electron and secondary electron detectors, and energy dispersive X-ray spectroscopy (EDS). The microstructure and elemental composition were further correlated with the wear and impact resistances of corresponding PDC cutters. Wear modes and impact toughening mechanisms of state-of-the-art PDCs were identified. Directions to further improve the wear and impact resistances of PDC cutters were proposed.

Keywords: fracture surface, microstructure, polycrystalline diamond, PDC, wear surface

Procedia PDF Downloads 53

Authors: Asmae Tafraouti, Yasmina Layouni, Pascal Kleimann

Abstract:

The growing market for Microsystems (MST) and Micro-Electromechanical Systems (MEMS) is driving the research for alternative manufacturing techniques to microelectronics-based technologies, which are generally expensive and time-consuming. Hot-embossing and micro-injection modeling of thermoplastics appear to be industrially viable processes. However, both require the use of master models, usually made in hard materials such as steel. These master models cannot be fabricated using standard microelectronics processes. Thus, other micromachining processes are used, such as laser machining or micro-electrical discharge machining (µEDM). In this work, µEDM has been used. The principle of µEDM is based on the use of a thin cylindrical micro-tool that erodes the workpiece surface. The two electrodes are immersed in a dielectric with a distance of a few micrometers (gap). When an electrical voltage is applied between the two electrodes, electrical discharges are generated, which cause material machining. In order to produce master models with high resolution and smooth surfaces, it is necessary to well control the discharge mechanism. However, several problems are encountered, such as a random electrical discharge process, the fluctuation of the discharge energy, the electrodes' polarity inversion, and the wear of the micro-tool. The effect of different parameters, such as the applied voltage, the working capacitor, the micro-tool diameter, and the initial gap, has been studied. This analysis helps to improve the machining performances, such as the workpiece surface condition and the lateral crater's gap.

Keywords: craters, electrical discharges, micro-electrical discharge machining, microsystems

Procedia PDF Downloads 74

Authors: Afsoun Nikravan, Parisa Babaei, Gulen Gullu

Abstract:

We aimed to study the association between house dust endotoxin, β-(1→3)-D-glucan, and asthma in a sample representative of the Turkish population. We analyzed data from 240 participants. The house dust was collected from the homes of 110 asthmatics and 130 control (without asthma) school-aged children (6-11 years old). House dust from the living room and from bedroom floors were analyzed for endotoxin and beta-glucan contents. House dust was analyzed for endotoxin content by the kinetic limulus amoebocyte lysate assay and for β-(1→3)-D-glucan by the inhibition enzyme immunoassay. The parents answered questions regarding potential determinants. We found geometric means 187.5 mg/m² for dust. According to statistical values, the endotoxin geometric mean was 13.86×103 EU/g for the control group and 6.16×103 EU/g for the asthma group. As a result, the amount of bacterial endotoxin was measured at a higher level in the homes of children without asthma. The geometric mean for beta-glucan was 46.52 µg/g and 44.39 µg/g for asthma and control groups, respectively. No associations between asthma and microbial agents were observed in Turkish children. High correlations (r > 0.75) were found between floor dust and endotoxin loads, while endotoxin and β-(1→3)-D-glucan concentrations were not correlated. The type of flooring (hard-surface or textile) was the strongest determinant for loads of floor dust and concentrations of endotoxin. Water damage and dampness at home were determinants of β-(1→3)-D-glucan concentrations. Endotoxin and β-(1→3)-D-glucan concentrations in Turkish house dust might lower than concentrations seen in other European countries.

Keywords: indoor air quality, asthma, microbial pollutants, case-control

Procedia PDF Downloads 124

Authors: Muhammad Jamil, Ning He, Wei Zhao

Abstract:

It is a rough estimation that the aerospace companies received orders of 37000 new aircraft, including the air ambulances, until 2037. And titanium alloys have a 15% contribution in modern aircraft's manufacturing owing to the high strength/weight ratio. Despite their application in the aerospace and medical equipment manufacturing industry, still, their high-speed machining puts a challenge in terms of tool wear, heat generation, and poor surface quality. Among titanium alloys, Ti-6Al-4V is the major contributor to aerospace application. However, its poor thermal conductivity (6.7W/mK) accumulates shear and friction heat at the tool-chip interface zone. To dissipate the heat generation and friction effect, cryogenic cooling, Minimum quantity lubrication (MQL), nanofluids, hybrid cryogenic-MQL, solid lubricants, etc., are applied frequently to underscore their significant effect on improving the machinability of Ti-6Al-4V. Nowadays, hybrid lubri-cooling is getting attention from researchers to explore their effect regarding the hard-to-cut Ti-6Al-4V. Therefore, this study is devoted to exploring the effect of hybrid ethanol-ester oil MQL regarding the cutting temperature, surface integrity, and tool life. As the ethanol provides -OH group and ester oil of long-chain molecules provide a tribo-film on the tool-workpiece interface. This could be a green manufacturing alternative for the manufacturing industry.

Keywords: hybrid lubri-cooling, surface roughness, tool wear, MQL

Procedia PDF Downloads 83

Authors: Pratibha Srivastava, Chithra V. J., Sudhakar S., Nitin K. D.

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A closed-loop system comprises of a controller, a response system, and an actuating system. The controller, which is the system under test for us, excites the actuators based on feedback from the sensors in a periodic manner. The sensors should provide the feedback to the System Under Test (SUT) within a deterministic time post excitation of the actuators. Any delay or miss in the generation of response or acquisition of excitation pulses may lead to control loop controller computation errors, which can be catastrophic in certain cases. Such systems categorised as hard real-time systems that need special strategies. The real-time operating systems available in the market may be the best solutions for such kind of simulations, but they pose limitations like the availability of the X Windows system, graphical interfaces, other user tools. In this paper, we present strategies that can be used on a general purpose operating system (Bare Linux Kernel) to achieve a deterministic deadline and hence have the added advantages of a GPOS with real-time features. Techniques shall be discussed how to make the time-critical application run with the highest priority in an uninterrupted manner, reduced network latency for distributed architecture, real-time data acquisition, data storage, and retrieval, user interactions, etc.

Keywords: real time data acquisition, real time kernel preemption, scheduling, network latency

Procedia PDF Downloads 147

Authors: Ida Ngurah

Abstract:

Indonesia is one of the most prone disaster countries, which has earthquake, tsunami or high wave, flood and landslide as well as volcano eruption and drought. Disaster risk reduction has been developing extensively and comprehensively, particularly after tsunami hit in 2004. Yet, saving people live including children and youth from disaster risk is still far from succeed. Poor management of environment, poor development of policy and high level of corruption has become challenges for Indonesia to save its people from disaster impact. Indonesia is struggling to ensure its future best investment, children and youth to have better protection when disaster strike in school hours and have basic knowledge on disaster risk reduction. The program of safe school is being initiated and developed by Plan Indonesia since 2010, yet this effort still needs to be elaborated. This paper is reviewing sporadic safe school programs that have been implemented or currently being implemented Plan Indonesia in few areas of Indonesia, including both rural and urban setting. Methods used are in-depth interview with dedicated person for the program from Plan Indonesia and its implementing patners and analysis of project documents. The review includes program’s goal and objectives, implementation activity, result and achievement as well as its monitoring and evaluation scheme. Moreover, paper will be showing challenges, lesson learned and best practices of the program. Eventually, paper will come up with recommendation for strategy for better implementation of safe school program in Indonesia.

Keywords: disaster impact, safe school, programs, children, youth

Procedia PDF Downloads 367

Authors: Kalsoom Shaikh, Saima Memon, Riffat Sultana

Abstract:

Water pollution affects amphibians because they are intimately water dependent. The permeable skin makes amphibians very sensitive to the physico-chemical parameters of their aquatic environment. They spawn in water bodies where quality of water can affect the growth, development, and survival of their eggs which may die even before hatching into larvae or developing into adults due to water contamination. Considering the importance of amphibians in agriculture, food web, ecosystem and pharmaceutics as well as adverse impact of environmental degradation on them, present study was proposed to comprehensively determine the status of their diversity and habitats in Sindh province of Pakistan so as to execute monitoring for their conservation in future. Physico-chemical parameters including pH, EC (electric conductivity), TDS (total dissolved solids), T-Hard (total hardness), T-Alk (total alkalinity), Cl (chloride), CO₂ (carbon dioxide), SO₄ (sulphate), PO₄ (phosphate), NO₂ (nitrite) and NO₃ (nitrate) were analyzed from amphibian habitats using instruments and methodology of analytical grade. The results of present study after being compared with scientific data provided by different researchers and EPA (environmental protection agency), it was concluded that amphibian habitats consisted of high values of analyzed parameters except pH and CO₂. Entire study area required an urgent implementation of conservation actions for saving amphibians.

Keywords: amphibians, diversity, habitats, physico-chemical parameters, water quality, Pakistan, Sindh Province

Procedia PDF Downloads 224

Authors: Abraham Castro-Alvarez, Luisaldo Sandate-Flores, Roberto Parra-Saldivar

Abstract:

The losing of crops during the whole production process is a problem that is affecting farmers in the whole world, as climate change affects the weather behavior. Stenocereus spp. is a tropical, exotic and endemic columnar cacti, it produces a colored and expensive fruit known how “pitaya”. The quality and value of the fruit, these species represent an attractive option for economical development in arid and semi-arid regions. This fruits are produced in Mexico, mainly in 4 regions, Mixteca Oaxaca-Puebla, Michoacan, Sinaloa-Sonora, Jalisco-Zacatecas. Pitaya can be an option to try mixed crop in this states due to the resistance to hard weather conditions. And also because of the marginalization problems that exist in these townships. As defined by the Population National Council it consists in the absence of development opportunities and the lack of capacity to get them. According to an analysis done in EsriPress ArcGis 10.1 the potential area in the country is almost the half of the territory being the total area of Mexico 1,965,249 km2 and the area with potential to produce pitaya 960,527 km2. This area covers part of the most affected townships that also have a few options of maize varieties making even harder the production of maize and exposing farmers to crop losing if conditions are good enough. Making pitaya a good option for these farmers to have an economic backup in their productions.

Keywords: maize, pitaya, rain fed, Stenocereus

Procedia PDF Downloads 318

Authors: Elena Carcano, James Ball

Abstract:

This work details the strategies adopted by the Italian Water Utilities during the distribution of water in emergency conditions which glide from earthquakes and droughts to floods and fires. Several water bureaus located over the national territory have been interviewed, and the collected information has been used in a database of potential interventions to be taken. The work discusses the actions adopted by water utilities. These are generally prioritized in order to minimize the social, temporal, and economic burden that the damaged and nearby areas need to support. Actions are defined relying on the Bayesian Network Approach, which constitutes the hard core of any decision support system. The Bayesian Networks give answers to interventions to real and most likely risky cases. The added value of this research consists in supplying the National Bureau, namely Protezione Civile, in charge of managing havoc and catastrophic situations with a univocal plot outline so as to be able to handle actions uniformly at the expense of different local laws or contradictory customs which squander any recovery conditions, proper technical service, and economic aids. The paper is organized as follows: in section 1, the introduction is stated; section 2 provides a brief discussion of BNNs (Bayesian Networks), section 3 introduces the adopted methodology; and in the last sections, results are presented, and conclusions are drawn.

Keywords: hierarchical process, strategic plan, water emergency conditions, water supply

Procedia PDF Downloads 160

Authors: Mohammed T. Hayajneh

Abstract:

Machining of Metal Matrix Composites (MMCs) is very significant process and has been a main problem that draws many researchers to investigate the characteristics of MMCs during different machining process. The poor machining properties of hard particles reinforced MMCs make drilling process a rather interesting task. Unlike drilling of conventional materials, many problems can be seriously encountered during drilling of MMCs, such as tool wear and cutting forces. Cutting tool wear is a very significant concern in industries. Cutting tool wear not only influences the quality of the drilled hole, but also affects the cutting tool life. Prediction the cutting tool life during drilling is essential for optimizing the cutting conditions. However, the relationship between tool life and cutting conditions, tool geometrical factors and workpiece material properties has not yet been established by any machining theory. In this research work, fuzzy subtractive clustering system has been used to model the cutting tool life in drilling of Al₂O₃ particle reinforced aluminum alloy composite to investigate of the effect of cutting conditions on cutting tool life. This investigation can help in controlling and optimizing of cutting conditions when the process parameters are adjusted. The built model for prediction the tool life is identified by using drill diameter, cutting speed, and cutting feed rate as input data. The validity of the model was confirmed by the examinations under various cutting conditions. Experimental results have shown the efficiency of the model to predict cutting tool life.

Keywords: composite, fuzzy, tool life, wear

Procedia PDF Downloads 295

Authors: Fatima Bouazza, Khadija Khedid, Lamiae Amallah, Aziz Mouhaddach, Basma Boukour, Jihane Ennadir, Rachida Hassikou

Abstract:

In order to combine milk and its derived products conservation and flavoring, Moroccans often used aromatic and medicinal plants. These plant extracts are endowed with several nutritive and therapeutic properties. This study constitutes a first national assessment of physico-chemical quality of sheep’s milk from moroccan Sardi breed and the evaluation of the antibacterial effect of three medicinal plants extracts: Aloe barbadensis Miller, Thymus satureioides and Mentha pulegium on flora isolated from this sheep's milk. 100 milk samples were collected in four regions of Morocco. The bacteria isolated were identified by classical and molecular methods (16S rRNA sequencing) and tested, according to the disk method, for their sensitivity to several antibiotics. The physico-chemical analyzes of sheep’s milk concerned the pH, titratable acidity, density, dry extract, freezing point and contents of: fat, proteins, lactose and calcium. The essential oils (EOs) of T. satureioides and M .pulegium were extracted by hydrodistillation and analyzed by GC / MS, while the Aloe vera leaf pulp was analyzed by the methods of Harborne and HPLC. A total number of 125 bacteria have been identified. Significant resistance to chemical antibiotics has been noted in LABs. The average temperature value of milk is around 57.15 °C, the pH is 6.56, the titratable acidity is around 3.4 ° D, the density is 1.035g / cm³ , the total dry extract is around 169.5g / l, the ash (9.8g / l), the freezing point (- 0.556 °C) while the average fat content is 67.85g / l . The samples richest in fat belong to the region of Settat, cradle of the Sardi breed, with a maximum average value of 74.4g / l. The average protein is 56g / l, lactose (39.92g / l), and calcium (1.855g / l). Analysis of the major components of EOs revealed the dominance of borneol in the case of T. satureioides and of pulegone in M. pulegium. Aloe vera gel contains alkaloids, flavonoids, catechic tannins, saponins and 1.60 µg / ml of aloin. The plant extracts have a bactericidal effect on E. coli, Klebsiellaoxytoca and Staphylococci and bacteriostatic effect on LABs of technological interest (Lactobacillus). As a result of this study, it is believed that the consumption of sardi sheep’s milk would be of nutritional benefit. Its richness in fat and proteins predisposes it for biotechnological development in the manufacture of cheese and yogurt. Also, the use of aromatic and medicinal plants, as natural additives would be of great benefit to flavor and maintain its quality.

Keywords: sheep’s milk, lactic flora, antimicrobial power, aloe barbadensis miller, thymus satureioides, mentha pulegium

Procedia PDF Downloads 125

Authors: Amirhossein Chambari

Abstract:

This article proposes a bi-objective model for the facility location problem subject to congestion (overcrowding). Motivated by implementations to locate servers in internet mirror sites, communication networks, one-server-systems, so on. This model consider for situations in which immobile (or fixed) service facilities are congested (or queued) by stochastic demand to behave as M/M/1/K queues. We consider for this problem two simultaneous perspectives; (1) Customers (desire to limit times of accessing and waiting for service) and (2) Service provider (desire to limit average facility idle-time). A bi-objective model is setup for facility location problem with two objective functions; (1) Minimizing sum of expected total traveling and waiting time (customers) and (2) Minimizing the average facility idle-time percentage (service provider). The proposed model belongs to the class of mixed-integer nonlinear programming models and the class of NP-hard problems. In addition, to solve the model, controlled elitist non-dominated sorting genetic algorithms (Controlled NSGA-II) and controlled elitist non-dominated ranking genetic algorithms (NRGA-I) are proposed. Furthermore, the two proposed metaheuristics algorithms are evaluated by establishing standard multiobjective metrics. Finally, the results are analyzed and some conclusions are given.

Keywords: bi-objective, facility location, queueing, controlled NSGA-II, NRGA-I

Procedia PDF Downloads 583

Authors: Qing Zhang, Jiachen Nie, Yujia Wen, Guanyuan Kou, Peng Yu, Kun Xia, Qin Yang, Li Ding

Abstract:

BACKGROUND: A facility layout problem (FLP) is an NP-complete (non-deterministic polynomial) problem, which is hard to obtain an exact optimal solution. FLP has been widely studied in various limited spaces and workflows. For example, cafeterias with many types of equipment for troops cause chaotic processes when dining. OBJECTIVE: This article tried to optimize the layout of troops’ cafeteria and to improve the overall efficiency of the dining process. METHODS: First, the original cafeteria layout design scheme was analyzed from an ergonomic perspective and two new design schemes were generated. Next, three facility layout models were designed, and further simulation was applied to compare the total time and density of troops between each scheme. Last, an experiment of the dining process with video observation and analysis verified the simulation results. RESULTS: In a simulation, the dining time under the second new layout is shortened by 2.25% and 1.89% (p<0.0001, p=0.0001) compared with the other two layouts, while troops-flow density and interference both greatly reduced in the two new layouts. In the experiment, process completing time and the number of interference reduced as well, which verified corresponding simulation results. CONCLUSIONS: Our two new layout schemes are tested to be optimal by a series of simulation and space experiments. In future research, similar approaches could be applied when taking layout-design algorithm calculation into consideration.

Keywords: layout optimization, dining efficiency, troops’ cafeteria, anylogic simulation, field experiment

Procedia PDF Downloads 143

Authors: Asmae Tafraouti, Yasmina Layouni, Pascal Kleimann

Abstract:

The growing market for Microsystems (MST) and Micro-Electromechanical Systems (MEMS) is driving the research for alternative manufacturing techniques to microelectronics-based technologies, which are generally expensive and time-consuming. Hot-embossing and micro-injection modeling of thermoplastics appear to be industrially viable processes. However, both require the use of master models, usually made in hard materials such as steel. These master models cannot be fabricated using standard microelectronics processes. Thus, other micromachining processes are used, as laser machining or micro-electrical discharge machining (µEDM). In this work, µEDM has been used. The principle of µEDM is based on the use of a thin cylindrical micro-tool that erodes the workpiece surface. The two electrodes are immersed in a dielectric with a distance of a few micrometers (gap). When an electrical voltage is applied between the two electrodes, electrical discharges are generated, which cause material machining. In order to produce master models with high resolution and smooth surfaces, it is necessary to well control the discharge mechanism. However, several problems are encountered, such as a random electrical discharge process, the fluctuation of the discharge energy, the electrodes' polarity inversion, and the wear of the micro-tool. The effect of different parameters, such as the applied voltage, the working capacitor, the micro-tool diameter, the initial gap, has been studied. This analysis helps to improve the machining performances, such: the workpiece surface condition and the lateral crater's gap.

Keywords: craters, electrical discharges, micro-electrical discharge machining (µEDM), microsystems

Procedia PDF Downloads 96

Authors: Joshua N. Edokpayi, John O. Odiyo, Patience P. Shikwambana

Abstract:

Water is a very rare natural resource in South Africa. Ga-Selati River is used for both domestic and industrial purposes. This study was carried out in order to assess the quality of Ga-Selati River in a mining area of Limpopo Province-Phalaborwa. The pH, Electrical Conductivity (EC) and Total Dissolved Solids (TDS) were determined using a Crinson multimeter while turbidity was measured using a Labcon Turbidimeter. The concentrations of Al, Ca, Cd, Cr, Fe, K, Mg, Mn, Na and Pb were analysed in triplicate using a Varian 520 flame atomic absorption spectrometer (AAS) supplied by PerkinElmer, after acid digestion with nitric acid in a fume cupboard. The average pH of the river from eight different sampling sites was 8.00 and 9.38 in wet and dry season respectively. Higher EC values were determined in the dry season (138.7 mS/m) than in the wet season (96.93 mS/m). Similarly, TDS values were higher in dry (929.29 mg/L) than in the wet season (640.72 mg/L) season. These values exceeded the recommended guideline of South Africa Department of Water Affairs and Forestry (DWAF) for domestic water use (70 mS/m) and that of the World Health Organization (WHO) (600 mS/m), respectively. Turbidity varied between 1.78-5.20 and 0.95-2.37 NTU in both wet and dry seasons. Total hardness of 312.50 mg/L and 297.75 mg/L as the concentration of CaCO3 was computed for the river in both the wet and the dry seasons and the river water was categorised as very hard. Mean concentration of the metals studied in both the wet and the dry seasons are: Na (94.06 mg/L and 196.3 mg/L), K (11.79 mg/L and 13.62 mg/L), Ca (45.60 mg/L and 41.30 mg/L), Mg (48.41 mg/L and 44.71 mg/L), Al (0.31 mg/L and 0.38 mg/L), Cd (0.01 mg/L and 0.01 mg/L), Cr (0.02 mg/L and 0.09 mg/L), Pb (0.05 mg/L and 0.06 mg/L), Mn (0.31 mg/L and 0.11 mg/L) and Fe (0.76 mg/L and 0.69 mg/L). Results from this study reveal that most of the metals were present in concentrations higher than the recommended guidelines of DWAF and WHO for domestic use and the protection of aquatic life.

Keywords: contamination, mining activities, surface water, trace metals

Procedia PDF Downloads 318

Authors: Leila Fozouni, Anahita Mazandarani

Abstract:

Background: Maternal infections are the most common cause of infections in infants, and the level of infection and its severity highly depends on the degree of colonization of the bacteria in the mother; so, the occurrence of aggressive diseases is not unpredictable in mothers with very high colonization. Group B Streptococcus is part of the normal flora of the gastrointestinal and genital tracts in women and is the leading cause of septicemia and meningitis in newborns. Today Zinc oxide nanoparticle is regarded as one of the most commonly used and safest nanoparticles for defeating Gram-positive and Gram-negative bacteria. This study aims to determine the antibacterial effects of Zinc oxide on the growth of drug-resistant group B Streptococcus strains isolated from pregnant women. Materials and Methods: This cross-sectional study was conducted on 150 pregnant women of 28–37 weeks admitted to seven hospitals and maternity wards in Golestan province, northeast of Iran. For bacterial identification, rectovaginal swabs were firstly inoculated to the Todd-Hewitt Broth and cultured in blood agar (containing 5% sheep blood). Then microbiologic and PCR methods were performed to detect group B Streptococci. Disk diffusion and broth microdilution tests were used to determine the bacterial susceptibility to antibiotics according to CLSI M100(2021) criteria. The antibacterial properties of Zinc oxide nanoparticles were evaluated using the agar well-diffusion method. Results: The prevalence of group B Streptococcus was 18% in pregnant women. Out of twenty-seven positive cultures, 62.96% were higher than thirty years old. Ninety percent and 45% of isolates were resistant to clindamycin and erythromycin, respectively, and susceptibility to cefazolin was 71%. In addition, susceptibility to ampicillin and penicillin were 74% and 55%, respectively. The results showed that 82% of erythromycin-resistant, 92% clindamycin-resistant, and 78% of cefazolin-resistant isolates were eliminated by zinc oxide nanoparticles at a concentration of 100 mg/L of the nanoparticle. Furthermore, ZnONPs could inhibit all drug-resistant isolates at a concentration of 200 mg/mL (MIC90 ≥ 200). Conclusion: Since the drug resistance of group B streptococci against various antibiotics is increasing, determining and investigating the drug-resistance pattern of this bacterium to different antibiotics in order to prevent arbitrary consumption of antibiotics by pregnant women and ultimately prevent Infant mortality seems necessary. Generally, ZnONPs showed a high antimicrobial effect, and it was revealed that the bactericide effect increases upon the increase in the concentration of the nanoparticle.

Keywords: group B beta-hemolytic streptococcus, pregnant women, zinc oxide nanoparticles, drug resistance

Procedia PDF Downloads 99

Authors: Hamed Movahedizadeh, Annuar Md Nassir, Mehdi Karimimalayer, Navid Samimi Sedeh, Ehsan Bagherpour

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The aim of this paper is to evaluate Tehran’s Stock Exchange (TSE) performance regarding with impact of four macroeconomic factors including world crude Oil Price (OP), World Gold Price (GP), Consumer Price Index (CPI) and total Supplied Oil by Iran (SO) from January 2006 to December 2012 that Iran faced with economic and oil sanctions. Iran's exports of crude oil and lease condensate reduced to roughly 1.5 million barrels per day (bbl/d) in 2012, compared to 2.5 million bbl/d in 2011 due to hard sanctions. Monthly data are collected and subjected to a battery of tests through ordinary least square by EViews7. This study found that gold price and oil price are positively correlated with stock returns while total oil supplied and consumer price index have negative relationship with stock index, however, consumer price index tends to become insignificant in stock index. While gold price and consumer price index have short run relationship with TSE index at 10% of significance level this amount for oil price is significant at 5% and there is no significant short run relationship between supplied oil and Tehran stock returns. Moreover, this study found that all macroeconomic factors have long-run relationship with Tehran Stock Exchange Index.

Keywords: consumer price index, gold price, macroeconomic, oil price, sanction, stock market, supplied oil

Procedia PDF Downloads 489

Authors: Hernan D. Mejia, Gilberto B. Gaitan, Mauricio A. Franco

Abstract:

420 steel is normally used in the manufacture of dental and surgical instrumentation, as well as parts in the chemical, pharmaceutical, and food industries, among others, where they must withstand heavy loads and often be in contact with corrosive environments, which leads to wear and deterioration of these steels in relatively short times. In the case of medical applications, the instruments made of this steel also suffer wear and corrosion during the repetitive sterilization processes due to the relatively low achievable hardness of just 50 HRC and its hardly acceptable resistance to corrosion. In order to improve the wear resistance of 420 steel, TiAlN coatings were deposited, increasing the aluminum content in the alloy by varying the power applied to the aluminum target of 900, 1100, and 1300 W. Evaluations using XRD, Micro Raman, XPS, AFM, SEM, and TEM showed a columnar growth crystal structure with an average thickness of 2 microns and consisting of the TiN and TiAlN phases, whose roughness and grain size decrease with a higher Al content. The AlN phase also appears in the sample deposited at 1300W. The hardness, determined by nanoindentation, initially increases with the aluminum content from 9.7 GPa to 17.1 GPa, but then decreases to 15.4 GPa for the sample with the highest aluminum content due to the appearance of hexagonal AlN and a decrease of harder TiN and TiAlN phases. It was observed that the wear coefficient had a contrary behavior, which took values of 2.7; 1.7 and 6.6x10⁻⁶ mm³/N.m, respectively. All the coated samples significantly improved the wear resistance of the uncoated 420 steel.

Keywords: hard coatings, magnetron sputtering, TiAlN coatings, surgical instruments, wear resistance

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Authors: Chia-Yen Lee, Hao-Jen Wang, Jhih-Hao Lai

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In recent years, infrared (IR) imaging has been considered as a potential tool to assess the efficacy of chemotherapy and early detection of breast cancer. Regions of tumor growth with high metabolic rate and angiogenesis phenomenon lead to the high temperatures. Observation of differences between the heat maps in long term is useful to help assess the growth of breast cancer cells and detect breast cancer earlier, wherein the multi-time infrared image alignment technology is a necessary step. Representative feature points detection and matching are essential steps toward the good performance of image registration and quantitative analysis. However, there is no clear boundary on the infrared images and the subject's posture are different for each shot. It cannot adhesive markers on a body surface for a very long period, and it is hard to find anatomic fiducial markers on a body surface. In other words, it’s difficult to detect and match features in an IR sequence images. In this study, automated feature detection and matching algorithms with two type of automatic feature points (i.e., vascular branch points and modified Harris corner) are developed respectively. The preliminary results show that the proposed method could identify the representative feature points on the IR breast images successfully of 98% accuracy and the matching results of 93% accuracy.

Keywords: Harris corner, infrared image, feature detection, registration, matching

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Authors: Adrian Ionut Nicoara, Denisa Ionela Ene, Alina Maria Holban, Cristina Busuioc

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At present, the development of materials with biomedical applications is a domain of interest that will produce a full series of benefits in engineering and medicine. In this sense, it is required to use a natural material, and this paper is focused on the development of a composite material based on bacterial cellulose – hydroxyapatite and silver nanoparticles with applications in hard tissue. Bacterial cellulose own features like biocompatibility, non-toxicity character and flexibility. Moreover, the bacterial cellulose can be conjugated with different forms of active silver to possess antimicrobial activity. Hydroxyapatite is well known that can mimic at a significant level the activity of the initial bone. The material was synthesized by using an ultrasound probe and finally characterized by several methods. Thereby, the morphological properties were analyzed by using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Because the synthesized material has medical application in restore the tissue and to fight against microbial invasion, the samples were tested from the biological point of view by evaluating the biodegradability in phosphate-buffered saline (PBS) and simulated body fluid (SBF) and moreover the antimicrobial effect was performed on Gram-positive bacterium Staphylococcus aureus, Gram-negative bacterium Escherichia coli, and fungi Candida albicans. The results reveal that the obtained material has specific characteristics for bone regeneration.

Keywords: bacterial cellulose, biomaterials, hydroxyapatite, scaffolds materials

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Authors: Xiuguo Zhao, He Li, Alireza Yazdani, Xiaoning Zheng, Xinxi Xu

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Wound infected poses a serious threat to the surgery on the patient during the process of surgery. Understanding the bacteria-carrying particles (BCPs) transportation and deposition in the open surgical wound model play essential role in protecting wound against being infected. Therefore BCPs transportation and deposition in the surgical wound model were investigated using force-coupling method (FCM) based computational fluid dynamics. The BCPs deposition in the wound was strongly associated with BCPs diameter and concentration. The results showed that the rise on the BCPs deposition was increasing not only with the increase of BCPs diameters but also with the increase of the BCPs concentration. BCPs deposition morphology was impacted by the combination of size distribution, airflow patterns and model geometry. The deposition morphology exhibited the characteristic with BCPs deposition on the sidewall in wound model and no BCPs deposition on the bottom of the wound model mainly because the airflow movement in one direction from up to down and then side created by laminar system constructing airflow patterns and then made BCPs hard deposit in the bottom of the wound model due to wound geometry limit. It was also observed that inertial impact becomes a main mechanism of the BCPs deposition. This work may contribute to next study in BCPs deposition limit, as well as wound infected estimation in surgical-site infections.

Keywords: BCPs deposition, computational fluid dynamics, force-coupling method (FCM), numerical simulation, open surgical wound model

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Authors: Lina Yang, Mao Wen, Jianhong Chen, Kan Zhang

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Molybdenum disulfide (MoS₂) represents a highly sought lubricant for reducing friction based on intrinsic layered structure, but for this reason, practical applications have been greatly restricted due to the fact that its low hardness would cause severe wear. Here, a novel TiMoN/MoSₓ composite coatings with TiMoN solid solution grains embedded into MoSₓ-based amorphous matrix has been successfully designed and synthesized, through magnetron co-sputtering technology. Desirably, in virtue of such special microstructure, superhardness and excellent toughness can be well achieved, along with an ultra-low wear rate at ~2×10⁻¹¹ mm³/Nm in the air environment, simultaneously, low friction at ~0.1 is maintained. It should be noted that this wear level is almost two orders of magnitude lower than that of pure TiN coating, and is, as we know, the lowest wear rate in dry sliding. Investigations of tribofilm reveal that it is amorphous MoS₂ in nature, and its formation arises directly from the MoSₓ amorphous matrix. Which contributes to effective lubrication behavior, coupled with excellent mechanical performances of such composite coating, exceptionally low wear can be guaranteed. The findings in this work suggest that the special composite structure makes it possible for the synthesis of super-hard and super-durable lubricative coating, offering guidance to synthesize ultrahigh performance protective coating for industrial application.

Keywords: hardness, MoS₂-containing composite coatings, toughness, tribological properties

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Authors: Mai Kaneda, Sarah Feeney

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This study examined the association between adult attachment security and career decision-making self-efficacy (CDMSE) among college students in the United States. Previous studies show that attachment security is associated with levels of CDMSE among college students. Given that a majority of studies examining career development variables have used parental attachment measures, this study adds to understanding of this phenomenon by utilizing a broader measure of attachment. The participants included 269 college students (76% female) between the ages of 19-29. An anonymous survey was distributed online via social media as well as in hard copy format in classrooms. Multiple regression analyses were conducted to determine the relationship between anxious and avoidant attachment and CDMSE. Results revealed anxious attachment was a significant predictor of CDMSE (B = -.13, p = .01), such that greater anxiety in attachment was associated with lower levels of CDMSE. When accounting for anxious attachment, avoidant attachment was no longer significant as a predictor of CDMSE (B = -.12, p = .10). The variance in college CDMSE explained by the model was 7%, F(2,267) = 9.51, p < .001. Results for anxious attachment are consistent with existing literature that finds insecure attachment to be related to lower levels of CDMSE, however the non-significant results for avoidant attachment as a predictor of CDMSE suggest not all types of attachment insecurity are equally related to CDMSE. Future research is needed to explore the nature of the relationship between different dimensions of attachment insecurity and CDMSE.

Keywords: attachment, career decision-making, college students, self-efficacy

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Authors: Oshienemen Albert, Dilanthi Amaratunga, Richard Haigh

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Globally, disasters of any form can affect the environment, built environment, the waterways, societies, nations and communities in diverse areas. The such impacts could cut across, economic loss, social setting, cultural and livelihood structures of affected population. Thus, the raise of disaster impacts across developing nations are alarming with decades impact due to the lack of hard and soft infrastructural development across communities, inconsistency in the governmental policy and implementation, making it difficult for disaster affected communities to bounce back when necessary, especially in Nigeria. The Nigeria disasters, especially oil spillages have affected diverse communities across the Niger Delta region for decades with little or nothing as external support for the broken livelihood structure, cultural and economic damages of the people. Though, in the spirit of contribution to the communities affected by oil spill and negative consequence of petroleum production, the federal government at different times established some impressionistic bodies and agencies to oversee the affairs of the region as with regards to oil spillages and development. Thus, the agencies contributions are yet to manifest in practice. This amplifies the quest for the structural clarities of the management systems and the resilience’s of the communities, to better equip the communities for any such disaster. Therefore, the study sets to explore the Nigerian disaster management systems and resilience concept at local community level. Thus, desk-based approach and interviews are employed for the synthesis while, drawing conclusion and recommendations.

Keywords: disaster, community, management, resilience

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Authors: Sayem Zafar, Mahmood Rahi

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Rigorous international maritime regulations are in place to limit boat and ship hydrocarbon emissions. The global sustainability goals are reducing the fuel consumption and minimizing the emissions from the ships and boats. These maritime sustainability goals have attracted a lot of research interest. Energy harvesting and storage system is designed in this study based on hybrid renewable and conventional energy systems. This energy harvesting and storage system is designed for marine applications, such as, boats and small ships. These systems can be utilized for mobile use or off-grid remote electrification. This study analyzed the use of micro power generation for boats and small ships. The energy harvesting and storage system has two distinct systems i.e. dockside shore-based system and on-board system. The shore-based system consists of a small wind turbine, photovoltaic (PV) panels, small gas turbine, hydrogen generator and high-pressure hydrogen storage tank. This dockside system is to provide easy access to the boats and small ships for supply of hydrogen. The on-board system consists of hydrogen storage tanks and fuel cells. The wind turbine and PV panels generate electricity to operate electrolyzer. A small gas turbine is used as a supplementary power system to contribute in case the hybrid renewable energy system does not provide the required energy. The electrolyzer performs the electrolysis on distilled water to produce hydrogen. The hydrogen is stored in high-pressure tanks. The hydrogen from the high-pressure tank is filled in the low-pressure tanks on-board seagoing vessels to operate the fuel cell. The boats and small ships use the hydrogen fuel cell to provide power to electric propulsion motors and for on-board auxiliary use. For shore-based system, a small wind turbine with the total length of 4.5 m and the disk diameter of 1.8 m is used. The small wind turbine dimensions make it big enough to be used to charge batteries yet small enough to be installed on the rooftops of dockside facility. The small dimensions also make the wind turbine easily transportable. In this paper, PV, sizing and solar flux are studied parametrically. System performance is evaluated under different operating and environmental conditions. The parametric study is conducted to evaluate the energy output and storage capacity of energy storage system. Results are generated for a wide range of conditions to analyze the usability of hybrid energy harvesting and storage system. This energy harvesting method significantly improves the usability and output of the renewable energy sources. It also shows that small hybrid energy systems have promising practical applications.

Keywords: energy harvesting, fuel cell, hybrid energy system, hydrogen, wind turbine

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Authors: Albert Suryaprawira

Abstract:

Patients requiring correction of severe Class III skeletal discrepancy historically has been among the most challenging treatments for orthodontists. Correction of an aesthetic and functional problem is crucially important. This is a case report of an adult male aged 18 years who complained of difficulty in chewing and speaking. Patient has a prominent profile with mandibular excess. The pre-treatment cephalometric radiograph was taken to analyse the skeletal problem and to measure the amount of bone movement and the prediction soft tissue response. The panoramic radiograph was also taken to analyse bone quality, bone abnormality, third molar impaction, etc. Before the surgery, the pre-surgical cephalometric radiograph was taken to re-evaluate the plan and to settle the final amount of bone cut. After the surgery, the post-surgical cephalometric radiograph was taken to confirm the result with the plan. The superimposition between those radiographs was performed to analyse the outcome. It includes the superimposition of the cranial base, maxilla, and mandible. Superimposition is important to describe the amount of hard and soft tissue movement. It is also important to predict the possibility of relapse after the surgery. The patient needs to understand all the surgical plan, outcome and relapse prevention. The surgery included mandibular set back by bilateral sagittal split osteotomies. Although the discrepancy was severe using this combination of treatment and the use of radiographic superimposition, an aesthetically pleasing and stable result was achieved.

Keywords: cephalometric, mandibular set back, orthognathic, superimposition

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Authors: Nazli Uren, Ayse Okur

Abstract:

Tactile comfort of a textile product is an essential property and a major concern when it comes to customer perceptions and preferences. The subjective nature of comfort and the difficulties regarding the simulation of human hand sensory feelings make it hard to establish a well-accepted link between tactile comfort and objective evaluations. On the other hand, shear behavior of a fabric is a mechanical parameter which can be measured by various objective test methods. The principal aim of this study is to determine the tactile comfort of commercially available denim fabrics by subjective measurements, create a tactile score database for denim fabrics and investigate the relations between tactile comfort and shear behavior. In-plane shear behaviors of 17 different commercially available denim fabrics with a variety of raw material and weave structure were measured by a custom design shear frame and conventional bias extension method in two corresponding diagonal directions. Tactile comfort of denim fabrics was determined via subjective customer evaluations as well. Aforesaid relations were statistically investigated and introduced as regression equations. The analyses regarding the relations between tactile comfort and shear behavior showed that there are considerably high correlation coefficients. The suggested regression equations were likewise found out to be statistically significant. Accordingly, it was concluded that the tactile comfort of denim fabrics can be estimated with a high precision, based on the results of in-plane shear behavior measurements.

Keywords: denim fabrics, in-plane shear behavior, linear regression estimation, tactile comfort

Procedia PDF Downloads 302