Search results for: yield improvement.
Commenced in January 2007
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Edition: International
Paper Count: 6554

Search results for: yield improvement.

4964 Oral Betahistine Versus Intravenous Diazepam in Acute Peripheral Vertigo: A Randomized, Double-Blind Controlled Trial

Authors: Saeed Abbasi, Davood Farsi, Soudabeh Shafiee Ardestani, Neda Valizadeh

Abstract:

Objectives: Peripheral vertigo is a common complaint of patients who are visited in emergency departments. In our study, we wanted to evaluate the effect of betahistine as an oral drug vs. intravenous diazepam for the treatment of acute peripheral vertigo. We also wanted to see the possibility of substitution of parenteral drug with an oral one with fewer side effects. Materials and Methods: In this randomized, double-blind study, 101 patients were enrolled in the study. The patients were divided in two groups in a double-blind randomized manner. Group A took oral placebo and 10 mg of intravenous diazepam. Group B received 8mg of oral betahistine and intravenous placebo. Patients’ symptoms and signs (Vertigo severity, Nausea, Vomiting, Nistagmus and Gate) were evaluated after 0, 2, 4, 6 hours by emergency physicians and data were collected by a questionnaire. Results: In both groups, there was significant improvement in vertigo (betahistine group P=0.02 and Diazepam group P=0.03). Analysis showed more improvement in vertigo severity after 4 hours of treatment in betahistine group comparing to diazepam group (P=0.02). Nausea and vomiting were significantly lower in patients receiving diazepam after 2 and 6 hours (P=0.02 & P=0.03).No statistically significant differences were found between the groups in nistagmus, equilibrium & vertigo duration. Conclusion: The results of this randomized trial showed that both drugs had acceptable therapeutic effects in peripheral vertigo, although betahistine was significantly more efficacious after 4 hours of drug intake. As for higher nausea and vomiting in betahistine group, physician should consider these side effects before drug prescription.

Keywords: acute peripheral vertigo, betahistine, diazepam, emergency department

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4963 Evaluation of the Role of Simulation and Virtual Reality as High-Yield Adjuncts to Paediatric Education

Authors: Alexandra Shipley

Abstract:

Background: Undergraduate paediatric teaching must overcome two major challenges: 1) balancing patient safety with active student engagement and 2) exposing students to a comprehensive range of pathologies within a relatively short clinical placement. Whilst lectures and shadowing on paediatric wards constitute the mainstay of learning, Simulation and Virtual Reality (VR) are emerging as effective teaching tools, which - immune to the unpredictability and seasonal variation of hospital presentations - could expose students to the entire syllabus more reliably, efficiently, and independently. We aim to evaluate the potential utility of Simulation and VR in addressing gaps within the traditional paediatric curriculum from the perspective of medical students. Summary of Work: Exposure to and perceived utility of various learning opportunities within the Paediatric and Emergency Medicine courses were assessed through a questionnaire completed by 5th year medical students (n=23). Summary of Results: Students reported limited exposure to several common acute paediatric presentations, such as bronchiolitis (41%), croup (32%) or pneumonia (14%), and to clinical emergencies, including cardiac/respiratory arrests or trauma calls (27%). Across all conditions, average self-reported confidence in assessment and management to the level expected of an FY1 is greater amongst those who observed at least one case (e.g. 7.6/10 compared with 3.6/10 for croup). Students rated exposure through Simulation or VR to be of similar utility to witnessing a clinical scenario on the ward. In free text responses, students unanimously favoured being ‘challenged’ through ‘hands-on’ patient interaction over passive shadowing, where it is ‘easy to zone out.’ In recognition of the fact that such independence is only appropriate in certain clinical situations, many students reported wanting more Simulation and VR teaching. Importantly, students raised the necessity of ‘proper debriefs’ after these sessions to maximise educational value. Discussion and Conclusion: Our questionnaire elicited several student-perceived challenges in paediatric education, including incomplete exposure to common pathologies and limited opportunities for active involvement in patient care. Indeed, these experiences seem to be important predictors of confidence. Quantitative and qualitative feedback suggests that VR and Simulation satisfy students’ self-reported appetite for independent engagement with authentic clinical scenarios. Take-aways: Our findings endorse further development of VR and Simulation as high-yield adjuncts to paediatric education.

Keywords: paediatric emergency education, simulation, virtual reality, medical education

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4962 Sentiment Analysis of Fake Health News Using Naive Bayes Classification Models

Authors: Danielle Shackley, Yetunde Folajimi

Abstract:

As more people turn to the internet seeking health-related information, there is more risk of finding false, inaccurate, or dangerous information. Sentiment analysis is a natural language processing technique that assigns polarity scores to text, ranging from positive, neutral, and negative. In this research, we evaluate the weight of a sentiment analysis feature added to fake health news classification models. The dataset consists of existing reliably labeled health article headlines that were supplemented with health information collected about COVID-19 from social media sources. We started with data preprocessing and tested out various vectorization methods such as Count and TFIDF vectorization. We implemented 3 Naive Bayes classifier models, including Bernoulli, Multinomial, and Complement. To test the weight of the sentiment analysis feature on the dataset, we created benchmark Naive Bayes classification models without sentiment analysis, and those same models were reproduced, and the feature was added. We evaluated using the precision and accuracy scores. The Bernoulli initial model performed with 90% precision and 75.2% accuracy, while the model supplemented with sentiment labels performed with 90.4% precision and stayed constant at 75.2% accuracy. Our results show that the addition of sentiment analysis did not improve model precision by a wide margin; while there was no evidence of improvement in accuracy, we had a 1.9% improvement margin of the precision score with the Complement model. Future expansion of this work could include replicating the experiment process and substituting the Naive Bayes for a deep learning neural network model.

Keywords: sentiment analysis, Naive Bayes model, natural language processing, topic analysis, fake health news classification model

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4961 A New Type Safety-Door for Earthquake Disaster Prevention: Part I

Authors: Daniel Y. Abebe, Jaehyouk Choi

Abstract:

From the past earthquake events, many people get hurt at the exit while they are trying to go out of the buildings because of the exit doors are unable to be opened. The door is not opened because it deviates from its the original position. The aim of this research is to develop and evaluate a new type safety door that keeps the door frame in its original position or keeps its edge angles perpendicular during and post-earthquake. The proposed door is composed of three components: outer frame joined to the wall, inner frame (door frame) and circular hollow section connected to the inner and outer frame which is used as seismic energy dissipating device.

Keywords: safety-door, earthquake disaster, low yield point steel, passive energy dissipating device, FE analysis

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4960 Designing Urban Spaces Differently: A Case Study of the Hercity Herstreets Public Space Improvement Initiative in Nairobi, Kenya

Authors: Rehema Kabare

Abstract:

As urban development initiatives continue to emerge and are implemented amid rapid urbanization and climate change effects in the global south, the plight of women is only being noticed. The pandemic exposed the atrocities, violence and unsafety women and girls face daily both in their homes and in public urban spaces. This is a result of poorly implemented and managed urban structures, which women have been left out of during design and implementation for centuries. The UN Habitat’s HerCity toolkit provides a unique opportunity to change course for both governments and civil society actors where women and girls are onboarded onto urban development initiatives, with their designs and ideas being the focal point. This toolkit proves that when women and girls design, they design for everyone. The HerCity HerStreets, Public Space Improvement Initiative, resulted in a design that focused on two aspects: Streets are a shared resource, and Streets are public spaces. These two concepts illustrate that for streets to be experienced effectively as cultural spaces, they need to be user-friendly, safe and inclusive. This report demonstrates how the HerCity HerStreets as a pilot project can be a benchmark for designing urban spaces in African cities. The project focused on five dimensions to improve the air quality of the space, the space allocation to street vending and bodaboda (passenger motorcycle) stops parking and the green coverage. The process displays how digital tools such as Minecraft and Kobo Toolbox can be utilized to improve citizens’ participation in the development of public spaces, with a special focus on including vulnerable groups such as women, girls and youth.

Keywords: urban space, sustainable development, gender and the city, digital tools and urban development

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4959 Estimation of Greenhouse Gas (GHG) Reductions from Solar Cell Technology Using Bottom-up Approach and Scenario Analysis in South Korea

Authors: Jaehyung Jung, Kiman Kim, Heesang Eum

Abstract:

Solar cell is one of the main technologies to reduce greenhouse gas (GHG). Thereby, accurate estimation of greenhouse gas reduction by solar cell technology is crucial to consider strategic applications of the solar cell. The bottom-up approach using operating data such as operation time and efficiency is one of the methodologies to improve the accuracy of the estimation. In this study, alternative GHG reductions from solar cell technology were estimated by a bottom-up approach to indirect emission source (scope 2) in Korea, 2015. In addition, the scenario-based analysis was conducted to assess the effect of technological change with respect to efficiency improvement and rate of operation. In order to estimate GHG reductions from solar cell activities in operating condition levels, methodologies were derived from 2006 IPCC guidelines for national greenhouse gas inventories and guidelines for local government greenhouse inventories published in Korea, 2016. Indirect emission factors for electricity were obtained from Korea Power Exchange (KPX) in 2011. As a result, the annual alternative GHG reductions were estimated as 21,504 tonCO2eq, and the annual average value was 1,536 tonCO2eq per each solar cell technology. Those results of estimation showed to be 91% levels versus design of capacity. Estimation of individual greenhouse gases (GHGs) showed that the largest gas was carbon dioxide (CO2), of which up to 99% of the total individual greenhouse gases. The annual average GHG reductions from solar cell per year and unit installed capacity (MW) were estimated as 556 tonCO2eq/yr•MW. Scenario analysis of efficiency improvement by 5%, 10%, 15% increased as much as approximately 30, 61, 91%, respectively, and rate of operation as 100% increased 4% of the annual GHG reductions.

Keywords: bottom-up approach, greenhouse gas (GHG), reduction, scenario, solar cell

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4958 Simultaneous Interpreting and Meditation: An Experimental Study on the Effects of Qigong Meditation on Simultaneous Interpreting Performance

Authors: Lara Bruno, Ilaria Tipà, Franco Delogu

Abstract:

Simultaneous interpreting (SI) is a demanding language task which includes the contemporary activation of different cognitive processes. This complex activity requires interpreters not only to be proficient in their working languages; but also to have a great ability in focusing attention and controlling anxiety during their performance. Effects of Qigong meditation techniques have a positive impact on several cognitive functions, including attention and anxiety control. This study aims at exploring the influence of Qigong meditation on the quality of simultaneous interpreting. 20 interpreting students, divided into two groups, were trained for 8 days in Qigong meditation practice. Before and after training, a brief simultaneous interpreting task was performed. Language combinations of group A and group B were respectively English-Italian and Chinese-Italian. Students’ performances were recorded and rated by independent evaluators. Assessments were based on 12 different parameters, divided into 4 macro-categories: content, form, delivery and anxiety control. To determine if there was any significant variation between the pre-training and post-training SI performance, ANOVA analyses were conducted on the ratings provided by the independent evaluators. Main results indicate a significant improvement of the interpreting performance after the meditation training intervention for both groups. However, group A registered a higher improvement compared to Group B. Nonetheless, positive effects of meditation have been found in all the observed macro-categories. Meditation was not only beneficial for speech delivery and anxiety control but also for cognitive and attention abilities. From a cognitive and pedagogical point of view, present results open new paths of research on the practice of meditation as a tool to improve SI performances.

Keywords: cognitive science, interpreting studies, Qigong meditation, simultaneous interpreting, training

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4957 Catalytic Cracking of Hydrocarbon over Zeolite Based Catalysts

Authors: Debdut Roy, Vidyasagar Guggilla

Abstract:

In this research, we highlight our exploratory work on modified zeolite based catalysts for catalytic cracking of hydrocarbons for production of light olefin i.e. ethylene and propylene. The work is focused on understanding the catalyst structure and activity correlation. Catalysts are characterized by surface area and pore size distribution analysis, inductively coupled plasma optical emission spectrometry (ICP-OES), Temperature Programmed Desorption (TPD) of ammonia, pyridine Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Thermo-gravimetric Analysis (TGA) and correlated with the catalytic activity. It is observed that the yield of lighter olefins increases with increase of Bronsted acid strength.

Keywords: catalytic cracking, zeolite, propylene, structure-activity correlation

Procedia PDF Downloads 218
4956 Combined Cervical Headache Snag with Cervical Snag Half Rotation Techniques on Cervicogenic Headache Patients

Authors: Wael Salah Shendy, Moataz Mohamed EL Semary, Hosam Salah Murad, Adham A. Mohamed

Abstract:

Background: Cervicogenic headache is a major problem in many people suffering from upper cervical dysfunction with a great conflict in its physical therapy management. Objectives: To determine the effect of C1-C2 Mulligan SNAGs mobilizations on cervicogenic headache and associated dizziness symptoms. Methods: Forty-eight patients with cervicogenic headache included in the study; from the outpatient clinic of Faculty of Physical Therapy, Cairo University, and New Cairo outpatient clinics, were randomly assigned into three equal groups; group A ( Headache SNAG), group B (C1-C2 SNAG rotation) and group C (combined). Their mean age was (29.37 ± 2.6), (29.31 ± 2.54) and (29.68 ± 2.65). Neck Disability Index used to examine neck pain intensity and CEH symptoms. 6 Items Headache Impact test '6-HIT' scale used to examine headache severity and its adverse effects on social life and functions. Flexion-Rotation Test 'FRT' also used to assess rotation ROM at the level of C1-C2 by 'CROM' device. Dizziness Handicap Inventory 'DHI' scale was used to evaluate dizziness symptoms. Evaluation is done pre and post treatment, and comparison between groups was quantified. Correlations between the examined parameters were also measured. Headache SNAG and C1-C2 Rotation SNAGs were done separately in group (A- B) and combined in group C as a treatment intervention. Results: Group C has Significant improvement in whole parameters compared to group A and B, positive correlation was found between NDI and 6-HIT scores compared to negative correlation between NDI and DHI scores. Conclusion: SNAGs mobilizations used in the study were effective in reducing cervicogenic headache and dizziness symptoms in all groups with a noticeable improvement in the combined group.

Keywords: cervicogenic headache, cervical headache snag, cervical snag half rotation, cervical dizziness

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4955 Comparison between the Quadratic and the Cubic Linked Interpolation on the Mindlin Plate Four-Node Quadrilateral Finite Elements

Authors: Dragan Ribarić

Abstract:

We employ the so-called problem-dependent linked interpolation concept to develop two cubic 4-node quadrilateral Mindlin plate finite elements with 12 external degrees of freedom. In the problem-independent linked interpolation, the interpolation functions are independent of any problem material parameters and the rotation fields are not expressed in terms of the nodal displacement parameters. On the contrary, in the problem-dependent linked interpolation, the interpolation functions depend on the material parameters and the rotation fields are expressed in terms of the nodal displacement parameters. Two cubic 4-node quadrilateral plate elements are presented, named Q4-U3 and Q4-U3R5. The first one is modelled with one displacement and two rotation degrees of freedom in every of the four element nodes and the second element has five additional internal degrees of freedom to get polynomial completeness of the cubic form and which can be statically condensed within the element. Both elements are able to pass the constant-bending patch test exactly as well as the non-zero constant-shear patch test on the oriented regular mesh geometry in the case of cylindrical bending. In any mesh shape, the elements have the correct rank and only the three eigenvalues, corresponding to the solid body motions are zero. There are no additional spurious zero modes responsible for instability of the finite element models. In comparison with the problem-independent cubic linked interpolation implemented in Q9-U3, the nine-node plate element, significantly less degrees of freedom are employed in the model while retaining the interpolation conformity between adjacent elements. The presented elements are also compared to the existing problem-independent quadratic linked-interpolation element Q4-U2 and to the other known elements that also use the quadratic or the cubic linked interpolation, by testing them on several benchmark examples. Simple functional upgrading from the quadratic to the cubic linked interpolation, implemented in Q4-U3 element, showed no significant improvement compared to the quadratic linked form of the Q4-U2 element. Only when the additional bubble terms are incorporated in the displacement and rotation function fields, which complete the full cubic linked interpolation form, qualitative improvement is fulfilled in the Q4-U3R5 element. Nevertheless, the locking problem exists even for the both presented elements, like in all pure displacement elements when applied to very thin plates modelled by coarse meshes. But good and even slightly better performance can be noticed for the Q4-U3R5 element when compared with elements from the literature, if the model meshes are moderately dense and the plate thickness not extremely thin. In some cases, it is comparable to or even better than Q9-U3 element which has as many as 12 more external degrees of freedom. A significant improvement can be noticed in particular when modeling very skew plates and models with singularities in the stress fields as well as circular plates with distorted meshes.

Keywords: Mindlin plate theory, problem-independent linked interpolation, problem-dependent interpolation, quadrilateral displacement-based plate finite elements

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4954 Clinical Parameters Response to Low Level Laser Versus Monochromatic Near Infrared Photo Energy in Diabetic Patient with Peripheral Neuropathy

Authors: Abeer Ahmed Abdehameed

Abstract:

Background: Diabetic sensorimotor polyneuropathy (DSP) is one of the most common micro vascular complications of type 2 diabetes. Loss of sensation is thought to contribute to lake of static and dynamic stability and increased risk of falling. Purpose: The purpose of this study was to compare the effects of low level laser (LLL) and monochromatic near infrared photo energy (MIRE) on pain , cutaneous sensation, static stability and index of lower limb blood flow in diabetic with peripheral neuropathy. Methods: Forty subjects with diabetic peripheral neuropathy were recruited for study. They were divided into two groups: The ( MIRE) group that included (20) patients and (LLL) group included (20) patients. All patients in the study had been subjected to various physical assessment procedures including pain, cutaneous sensation, Doppler flow meter and static stability assessments. The baseline measurements were followed by treatment sessions that conducted twice a week for 6 successive weeks. Results: The statistical analysis of the data had revealed significant improvement of the pain in both groups, with significant improvement in cutaneous sensation and static balance in (MIRE) group compared to (LLL) group; on the other hand results showed no significant differences on lower limb blood flow in both groups. Conclusion: Low level laser and monochromatic near infrared therapy can improve painful symptoms in patients with diabetic neuropathy. On the other hand (MIRE) is useful in improving cutaneous sensation and static stability in patients with diabetic neuropathy.

Keywords: diabetic neuropathy, doppler flow meter, low level laser, monochromatic near infrared photo energy

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4953 Larger Diameter 22 MM-PDC Cutter Greatly Improves Drilling Efficiency of PDC Bit

Authors: Fangyuan Shao, Wei Liu, Deli Gao

Abstract:

With the increasing speed of oil and gas exploration, development and production at home and abroad, the demand for drilling speed up technology is becoming more and more critical to reduce the development cost. Highly efficient and personalized PDC bit is important equipment in the bottom hole assembly (BHA). Therefore, improving the rock-breaking efficiency of PDC bits will help reduce drilling time and drilling cost. Advances in PDC bit technology have resulted in a leapfrogging improvement in the rate of penetration (ROP) of PDC bits over roller cone bits in soft to medium-hard formations. Recently, with the development of PDC technology, the diameter of the PDC tooth can be further expanded. The maximum diameter of the PDC cutter used in this paper is 22 mm. According to the theoretical calculation, under the same depth of cut (DOC), the 22mm-PDC cutter increases the exposure of the cutter, and the increase of PDC cutter diameter helps to increase the cutting area of the PDC cutter. In order to evaluate the cutting performance of the 22 mm-PDC cutter and the existing commonly used cutters, the 16 mm, 19 mm and 22 mm PDC cutter was selected put on a vertical turret lathe (VTL) in the laboratory for cutting tests under different DOCs. The DOCs were 0.5mm, 1.0 mm, 1.5 mm and 2.0 mm, 2.5 mm and 3 mm, respectively. The rock sample used in the experiment was limestone. Results of laboratory tests have shown the new 22 mm-PDC cutter technology greatly improved cutting efficiency. On the one hand, as the DOC increases, the mechanical specific energy (MSE) of all cutters decreases, which means that the cutting efficiency increases. On the other hand, under the same DOC condition, the larger the cutter diameter is, the larger the working area of the cutter is, which leads to higher the cutting efficiency. In view of the high performance of the 22 mm-PDC cutters, which was applied to carry out full-scale bit field experiments. The result shows that the bit with 22mm-PDC cutters achieves a breakthrough improvement of ROP than that with conventional 16mm and 19mm cutters in offset well drilling.

Keywords: polycrystalline diamond compact, 22 mm-PDC cutters, cutting efficiency, mechanical specific energy

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4952 The Development and Testing of Greenhouse Comprehensive Environment Control System

Authors: Mohammed Alrefaie, Yaser Miaji

Abstract:

Greenhouses provide a convenient means to grow plants in the best environment. They achieve this by trapping heat from the sunlight and using artificial means to enhance the environment of the greenhouse. This includes controlling factors such as air flow, light intensity and amount of water among others that can have a big impact on plant growth. The aim of the greenhouse is to give maximum yield from plants possible. This report details the development and testing of greenhouse environment control system that can regulate light intensity, airflow and power supply inside the greenhouse. The details of the module development to control these three factors along with results of testing are presented.

Keywords: greenhouse, control system, light intensity, comprehensive environment

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4951 Enhancing the Implementation Strategy of Simultaneous Operations (SIMOPS) for the Major Turnaround at Pertamina Plaju Refinery

Authors: Fahrur Rozi, Daniswara Krisna Prabatha, Latief Zulfikar Chusaini

Abstract:

Amidst the backdrop of Pertamina Plaju Refinery, which stands as the oldest and historically less technologically advanced among Pertamina's refineries, lies a unique challenge. Originally integrating facilities established by Shell in 1904 and Stanvac (originally Standard Oil) in 1926, the primary challenge at Plaju Refinery does not solely revolve around complexity; instead, it lies in ensuring reliability, considering its operational history of over a century. After centuries of existence, Plaju Refinery has never undergone a comprehensive major turnaround encompassing all its units. The usual practice involves partial turnarounds that are sequentially conducted across its primary, secondary, and tertiary units (utilities and offsite). However, a significant shift is on the horizon. In the Q-IV of 2023, the refinery embarks on its first-ever major turnaround since its establishment. This decision was driven by the alignment of maintenance timelines across various units. Plaju Refinery's major turnaround was scheduled for October-November 2023, spanning 45 calendar days, with the objective of enhancing the operational reliability of all refinery units. The extensive job list for this turnaround encompasses 1583 tasks across 18 units/areas, involving approximately 9000 contracted workers. In this context, the Strategy of Simultaneous Operations (SIMOPS) execution emerges as a pivotal tool to optimize time efficiency and ensure safety. A Hazard Effect Management Process (HEMP) has been employed to assess the risk ratings of each task within the turnaround. Out of the tasks assessed, 22 are deemed high-risk and necessitate mitigation. The SIMOPS approach serves as a preventive measure against potential incidents. It is noteworthy that every turnaround period at Pertamina Plaju Refinery involves SIMOPS-related tasks. In this context, enhancing the implementation strategy of "Simultaneous Operations (SIMOPS)" becomes imperative to minimize the occurrence of incidents. At least four improvements have been introduced in the enhancement process for the major turnaround at Refinery Plaju. The first improvement involves conducting systematic risk assessment and potential hazard mitigation studies for SIMOPS tasks before task execution, as opposed to the previous on-site approach. The second improvement includes the completion of SIMOPS Job Mitigation and Work Matrices Sheets, which was often neglected in the past. The third improvement emphasizes comprehensive awareness to workers/contractors regarding potential hazards and mitigation strategies for SIMOPS tasks before and during the major turnaround. The final improvement is the introduction of a daily program for inspecting and observing work in progress for SIMOPS tasks. Prior to these improvements, there was no established program for monitoring ongoing activities related to SIMOPS tasks during the turnaround. This study elucidates the steps taken to enhance SIMOPS within Pertamina, drawing from the experiences of Plaju Refinery as a guide. A real actual case study will be provided from our experience in the operational unit. In conclusion, these efforts are essential for the success of the first-ever major turnaround at Plaju Refinery, with the SIMOPS strategy serving as a central component. Based on these experiences, enhancements have been made to Pertamina's official Internal Guidelines for Executing SIMOPS Risk Mitigation, benefiting all Pertamina units.

Keywords: process safety management, turn around, oil refinery, risk assessment

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4950 Enhancing Nursing Teams' Learning: The Role of Team Accountability and Team Resources

Authors: Sarit Rashkovits, Anat Drach- Zahavy

Abstract:

The research considers the unresolved question regarding the link between nursing team accountability and team learning and the resulted team performance in nursing teams. Empirical findings reveal disappointing evidence regarding improvement in healthcare safety and quality. Therefore, there is a need in advancing managerial knowledge regarding the factors that enhance constant healthcare teams' proactive improvement efforts, meaning team learning. We first aim to identify the organizational resources that are needed for team learning in nursing teams; second, to test the moderating role of nursing teams' learning resources in the team accountability-team learning link; and third, to test the moderated mediation model suggesting that nursing teams' accountability affects team performance by enhancing team learning when relevant resources are available to the team. We point on the intervening role of three team learning resources, namely time availability, team autonomy and performance data on the relation between team accountability and team learning and test the proposed moderated mediation model on 44 nursing teams (462 nurses and 44 nursing managers). The results showed that, as was expected, there was a positive significant link between team accountability and team learning and the subsequent team performance when time availability and team autonomy were high rather than low. Nevertheless, the positive team accountability- team learning link was significant when team performance feedback was low rather than high. Accordingly, there was a positive mediated effect of team accountability on team performance via team learning when either time availability or team autonomy were high and the availability of team performance data was low. Nevertheless, this mediated effect was negative when time availability and team autonomy were low and the availability of team performance data was high. We conclude that nurturing team accountability is not enough for achieving nursing teams' learning and the subsequent improved team performance. Rather there is need to provide nursing teams with adequate time, autonomy, and be cautious with performance feedback, as the latter may motivate nursing teams to repeat routine work strategies rather than explore improved ones.

Keywords: nursing teams' accountability, nursing teams' learning, performance feedback, teams' autonomy

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4949 Benefits of a Topical Emollient Product in the Management of Canine Nasal Hyperkeratosis

Authors: Christelle Navarro, Sébastien Viaud, Carole Gard, Bruno Jahier

Abstract:

Background: Idiopathic or familial nasal hyperkeratosis (NHK) may be considered a cosmetic issue in its uncomplicated form. Nevertheless, prevention of secondary lesions such as fissures or infections could be advised by proper management. The objective of this open-field study is to evaluate the benefits of a moisturizing balm in privately owned dogs with NHK, using an original validation grid for both investigator and owner assessments. Methods: Dogs with idiopathic or familial NHK received a vegetable-based ointment (Sensiderm® Balm, MP Labo, France) BID for 60 days. A global dermatological score (GDS) was defined using the sum of 4 criteria (“dryness,” “lichenification”, “crusts,” and “affected area”) on a 0 (no) to 3 (severe or > 2/3 extension) scale. Evaluation of this GDS (0-12) on D0, D30, and D60, by owners and investigators was the main outcome. The score’s percentage decrease versus D0, the evolution of each individual score, the correlation between observers, and the evaluation of clinical improvement and animal discomfort on VAS (0-10) during follow-up were analysed. Results: The global dermatological score significantly decreased over time (p<0.0001) for all observers. The decrease reached 44.9% and 54.3% at D30 and 54.5% and 62.3% at D60, for investigators and owners, respectively. “Dryness”, “Lichenification,” and “Affected area scores” decreased significantly and steadily over time compared to Day 0 for both investigators and owners (p < 0.001 and p = 0.001 for investigator assessment of dryness). All but one score (lichenification) were correlated at all times between observers (only at D60 for crusts). Whoever the observer, clinical improvement was always above 7. At D30 and until D60, “animal discomfort” was more than halved. Owner satisfaction was high as soon as D30 (8.1/10). No adverse effects were reported. Conclusion and clinical importance: The positive results confirm the benefits and safety of a moisturizing balm when used in dogs with uncomplicated NHK.

Keywords: hyperkeratosis, nose, dog, moisturizer

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4948 Effects of Oral L-Carnitine on Liver Functions after Trans arterial Chemoembolization in Hepatocellular Carcinoma Patients

Authors: Ali Kassem, Aly Taha, Abeer Hassan, Kazuhide Higuchi

Abstract:

Introduction: Trans arterial chemoembolization (TACE) for hepatocellular carcinoma (HCC) is usually followed by hepatic dysfunction that limits its efficacy. L-carnitine is recently studied as hepatoprotective agent. Our aim is to evaluate the L-carnitine effects against the deterioration of liver functions after TACE. Method: 53 patients with intermediate stage HCC were assigned into two groups; L-carnitine group (26 patients) who received L-carnitine 300 mg tablet twice daily from 2 weeks before to 12 weeks after TACE and control group (27 patients) without L-carnitine therapy. 28 of studied patients received branched chain amino acids granules. Results: There were significant differences between L-carnitine Vs. control group in mean serum albumin change from baseline to 1 week and 4 weeks after TACE (p < 0.05). L-Carnitine maintained Child-Pugh score at 1 week after TACE and exhibited improvement at 4 weeks after TACE (p < 0.01 Vs 1 week after TACE). Control group has significant Child-Pugh score deterioration from baseline to 1 week after TACE (p < 0.05) and 12 weeks after TACE (p < 0.05). There were significant differences between L-carnitine and control groups in mean Child-Pugh score change from baseline to 4 weeks (p < 0.05) and 12 weeks after TACE (p < 0.05). L-carnitine displayed improvement in (PT) from baseline to 1 week, 4 w (p < 0.05) and 12 weeks after TACE. PT in control group declined less than baseline along all follow up intervals. Total bilirubin in L-carnitine group decreased at 1 week post TACE while in control group, it significantly increased at 1 week (p = 0.01). ALT and C-reactive protein elevation were suppressed at 1 week after TACE in Lcarnitine group. The hepatoprotective effects of L-carnitine were enhanced by concomitant use of branched chain amino acids. Conclusion: L-carnitine and BCAA combination therapy offer a novel supportive strategy after TACE in HCC patients.

Keywords: hepatocellular carcinoma, L-carnitine, liver functions , trans-arterial embolization

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4947 Application of Thermoplastic Microbioreactor to the Single Cell Study of Budding Yeast to Decipher the Effect of 5-Hydroxymethylfurfural on Growth

Authors: Elif Gencturk, Ekin Yurdakul, Ahmet Y. Celik, Senol Mutlu, Kutlu O. Ulgen

Abstract:

Yeast cells are generally used as a model system of eukaryotes due to their complex genetic structure, rapid growth ability in optimum conditions, easy replication and well-defined genetic system properties. Thus, yeast cells increased the knowledge of the principal pathways in humans. During fermentation, carbohydrates (hexoses and pentoses) degrade into some toxic by-products such as 5-hydroxymethylfurfural (5-HMF or HMF) and furfural. HMF influences the ethanol yield, and ethanol productivity; it interferes with microbial growth and is considered as a potent inhibitor of bioethanol production. In this study, yeast single cell behavior under HMF application was monitored by using a continuous flow single phase microfluidic platform. Microfluidic device in operation is fabricated by hot embossing and thermo-compression techniques from cyclo-olefin polymer (COP). COP is biocompatible, transparent and rigid material and it is suitable for observing fluorescence of cells considering its low auto-fluorescence characteristic. The response of yeast cells was recorded through Red Fluorescent Protein (RFP) tagged Nop56 gene product, which is an essential evolutionary-conserved nucleolar protein, and also a member of the box C/D snoRNP complexes. With the application of HMF, yeast cell proliferation continued but HMF slowed down the cell growth, and after HMF treatment the cell proliferation stopped. By the addition of fresh nutrient medium, the yeast cells recovered after 6 hours of HMF exposure. Thus, HMF application suppresses normal functioning of cell cycle but it does not cause cells to die. The monitoring of Nop56 expression phases of the individual cells shed light on the protein and ribosome synthesis cycles along with their link to growth. Further computational study revealed that the mechanisms underlying the inhibitory or inductive effects of HMF on growth are enriched in functional categories of protein degradation, protein processing, DNA repair and multidrug resistance. The present microfluidic device can successfully be used for studying the effects of inhibitory agents on growth by single cell tracking, thus capturing cell to cell variations. By metabolic engineering techniques, engineered strains can be developed, and the metabolic network of the microorganism can thus be manipulated such that chemical overproduction of target metabolite is achieved along with the maximum growth/biomass yield.  

Keywords: COP, HMF, ribosome biogenesis, thermoplastic microbioreactor, yeast

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4946 Ensuring Quality in DevOps Culture

Authors: Sagar Jitendra Mahendrakar

Abstract:

Integrating quality assurance (QA) practices into DevOps culture has become increasingly important in modern software development environments. Collaboration, automation and continuous feedback characterize the seamless integration of DevOps development and operations teams to achieve rapid and reliable software delivery. In this context, quality assurance plays a key role in ensuring that software products meet the highest quality, performance and reliability standards throughout the development life cycle. This brief explores key principles, challenges, and best practices related to quality assurance in a DevOps culture. This emphasizes the importance of quality transfer in the development process, as quality control processes are integrated in every step of the DevOps process. Automation is the cornerstone of DevOps quality assurance, enabling continuous testing, integration and deployment and providing rapid feedback for early problem identification and resolution. In addition, the summary addresses the cultural and organizational challenges of implementing quality assurance in DevOps, emphasizing the need to foster collaboration, break down silos, and promote a culture of continuous improvement. It also discusses the importance of toolchain integration and capability development to support effective QA practices in DevOps environments. Moreover, the abstract discusses the cultural and organizational challenges in implementing QA within DevOps, emphasizing the need for fostering collaboration, breaking down silos, and nurturing a culture of continuous improvement. It also addresses the importance of toolchain integration and skills development to support effective QA practices within DevOps environments. Overall, this collection works at the intersection of QA and DevOps culture, providing insights into how organizations can use DevOps principles to improve software quality, accelerate delivery, and meet the changing demands of today's dynamic software. landscape.

Keywords: quality engineer, devops, automation, tool

Procedia PDF Downloads 58
4945 Quality Assurance for the Climate Data Store

Authors: Judith Klostermann, Miguel Segura, Wilma Jans, Dragana Bojovic, Isadora Christel Jimenez, Francisco Doblas-Reyees, Judit Snethlage

Abstract:

The Climate Data Store (CDS), developed by the Copernicus Climate Change Service (C3S) implemented by the European Centre for Medium-Range Weather Forecasts (ECMWF) on behalf of the European Union, is intended to become a key instrument for exploring climate data. The CDS contains both raw and processed data to provide information to the users about the past, present and future climate of the earth. It allows for easy and free access to climate data and indicators, presenting an important asset for scientists and stakeholders on the path for achieving a more sustainable future. The C3S Evaluation and Quality Control (EQC) is assessing the quality of the CDS by undertaking a comprehensive user requirement assessment to measure the users’ satisfaction. Recommendations will be developed for the improvement and expansion of the CDS datasets and products. User requirements will be identified on the fitness of the datasets, the toolbox, and the overall CDS service. The EQC function of the CDS will help C3S to make the service more robust: integrated by validated data that follows high-quality standards while being user-friendly. This function will be closely developed with the users of the service. Through their feedback, suggestions, and contributions, the CDS can become more accessible and meet the requirements for a diverse range of users. Stakeholders and their active engagement are thus an important aspect of CDS development. This will be achieved with direct interactions with users such as meetings, interviews or workshops as well as different feedback mechanisms like surveys or helpdesk services at the CDS. The results provided by the users will be categorized as a function of CDS products so that their specific interests will be monitored and linked to the right product. Through this procedure, we will identify the requirements and criteria for data and products in order to build the correspondent recommendations for the improvement and expansion of the CDS datasets and products.

Keywords: climate data store, Copernicus, quality, user engagement

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4944 Eli-Twist Spun Yarn: An Alternative to Conventional Sewing Thread

Authors: Sujit Kumar Sinha, Madan Lal Regar

Abstract:

Sewing thread plays an important role in the transformation of a two-dimensional fabric into a three-dimensional garment. The interaction of the sewing thread with the fabric at the seam not only influences the appearance of a garment but also its performance. Careful selection of sewing thread and associated parameters can only help in improvement. Over the years, ring spinning has been dominating the yarn market. In the pursuit of improvement to challenge its dominance alternative technology has also been developed. But no real challenge has been posed by the any of the developed spinning systems. Eli-Twist spinning system can be a new method of yarn manufacture to provide a product with improved mechanical and physical properties with respect to the conventional ring spun yarn. The system, patented by Suessen has gained considerable attention in the recent times. The process of produces a two-ply compact yarn with improved fiber utilization. It produces a novel structure combining all advantages of condensing and doubling. In the present study, sewing threads of three different counts each from cotton, polyester and polyester/cotton (50/50) blend were produced on a ring and Eli-Twist systems. A twist multiplier of 4.2 was used to produce all the yarns. A comparison of hairiness, tensile strength and coefficient of friction with conventional ring yarn was made. Eli-Twist yarn has shown better frictional characteristics, better tensile strength and less hairiness. The performance of the Eli-Twist sewing thread has also been found to be better than the conventional 2-ply sewing thread. The performance was estimated through seam strength, seam elongation and seam efficiency of sewn fabric. Eli-Twist sewing thread has shown less friction, less hairiness, and higher tensile strength. Eli-Twist sewing thread resulted in better seam characteristics in comparison to conventional 2-ply sewing thread.

Keywords: ring spun yarn, Eli-Twist yarn, sewing thread, seam strength, seam elongation, seam efficiency

Procedia PDF Downloads 197
4943 On Phase Based Stereo Matching and Its Related Issues

Authors: András Rövid, Takeshi Hashimoto

Abstract:

The paper focuses on the problem of the point correspondence matching in stereo images. The proposed matching algorithm is based on the combination of simpler methods such as normalized sum of squared differences (NSSD) and a more complex phase correlation based approach, by considering the noise and other factors, as well. The speed of NSSD and the preciseness of the phase correlation together yield an efficient approach to find the best candidate point with sub-pixel accuracy in stereo image pairs. The task of the NSSD in this case is to approach the candidate pixel roughly. Afterwards the location of the candidate is refined by an enhanced phase correlation based method which in contrast to the NSSD has to run only once for each selected pixel.

Keywords: stereo matching, sub-pixel accuracy, phase correlation, SVD, NSSD

Procedia PDF Downloads 468
4942 Tourism Policy Challenges in Post-Soviet Georgia

Authors: Merab Khokhobaia

Abstract:

The research of Georgian tourism policy challenges is important, as the tourism can play an increasing role for the economic growth and improvement of standard of living of the country even with scanty resources, at the expense of improved creative approaches. It is also important to make correct decisions at macroeconomic level, which will be accordingly reflected in the successful functioning of the travel companies and finally, in the improvement of economic indicators of the country. In order to correctly orient sectoral policy, it is important to precisely determine its role in the economy. Development of travel industry has been considered as one of the priorities in Georgia; the country has unique cultural heritage and traditions, as well as plenty of natural resources, which are a significant precondition for the development of tourism. Despite the factors mentioned above, the existing resources are not completely utilized and exploited. This work represents a study of subjective, as well as objective reasons of ineffective functioning of the sector. During the years of transformation experienced by Georgia, the role of travel industry in economic development of the country represented the subject of continual discussions. Such assessments were often biased and they did not rest on specific calculations. This topic became especially popular on the ground of market economy, because reliable statistical data have a particular significance in the designing of tourism policy. In order to deeply study the aforementioned issue, this paper analyzes monetary, as well as non-monetary indicators. The research widely included the tourism indicators system; we analyzed the flaws in reporting of the results of tourism sector in Georgia. Existing defects are identified and recommendations for their improvement are offered. For stable development tourism, similarly to other economic sectors, needs a well-designed policy from the perspective of national, as well as local, regional development. The tourism policy must be drawn up in order to efficiently achieve our goals, which were established in short-term and long-term dynamics on the national or regional scale of specific country. The article focuses on the role and responsibility of the state institutes in planning and implementation of the tourism policy. The government has various tools and levers, which may positively influence the processes. These levers are especially important in terms of international, as well as internal tourism development. Within the framework of this research, the regulatory documents, which are in force in relation to this industry, were also analyzed. The main attention is turned to their modernization and necessity of their compliance with European standards. It is a current issue to direct the efforts of state policy on support of business by implementing infrastructural projects, as well as by development of human resources, which may be possible by supporting the relevant higher and vocational studying-educational programs.

Keywords: regional development, tourism industry, tourism policy, transition

Procedia PDF Downloads 263
4941 Effect of vr Based Wii Fit Training on Muscle Strength, Sensory Integration Ability and Walking Abilities in Patients with Parkinson's Disease: A Randomized Control Trial

Authors: Ying-Yi Laio, Yea-Ru Yang, Yih-Ru Wu, Ray-Yau Wang

Abstract:

Background: Virtual reality (VR) systems are proved to increase motor performance in stroke and elderly. However, the effects have not been established in patients with Parkinson’s disease (PD). Purpose: To examine the effects of VR based training in improving muscle strength, sensory integration ability and walking abilities in patients with PD by a randomized controlled trial. Method: Thirty six participants with diagnosis of PD were randomly assigned to one of the three groups (n=12 for each group). Participants received VR-based Wii Fit exercise (VRWii group) or traditional exercise (TE group) for 45 minutes, followed by treadmill training for another 15 minutes for 12 sessions in 6 weeks. Participants in the control group received no structured exercise program but fall-prevention education. Outcomes included lower extremity muscle strength, sensory integration ability, walking velocity, stride length, and functional gait assessment (FGA). All outcomes were assessed at baseline, after training and at 1-month follow-up. Results: Both VRWii and TE groups showed more improvement in level walking velocity, stride length, FGA, muscle strength and vestibular system integration than control group after training and at 1-month follow-up. The VRWii training, but not the TE training, resulted in more improvement in visual system integration than the control. Conclusions: VRWii training is as beneficial as traditional exercise in improving walking abilities, sensory integration ability and muscle strength in patients with PD, and such improvements persisted at least for 1 month. The VRWii training is then suggested to be implemented in patients with PD.

Keywords: virtual reality, walking, sensory integration, muscle strength, Parkinson’s disease

Procedia PDF Downloads 329
4940 Investigations on Pyrolysis Model for Radiatively Dominant Diesel Pool Fire Using Fire Dynamic Simulator

Authors: Siva K. Bathina, Sudheer Siddapureddy

Abstract:

Pool fires are formed when the flammable liquid accidentally spills on the ground or water and ignites. Pool fire is a kind of buoyancy-driven and diffusion flame. There have been many pool fire accidents caused during processing, handling and storing of liquid fuels in chemical and oil industries. Such kind of accidents causes enormous damage to property as well as the loss of lives. Pool fires are complex in nature due to the strong interaction among the combustion, heat and mass transfers and pyrolysis at the fuel surface. Moreover, the experimental study of such large complex fires involves fire safety issues and difficulties in performing experiments. In the present work, large eddy simulations are performed to study such complex fire scenarios using fire dynamic simulator. A 1 m diesel pool fire is considered for the studied cases, and diesel is chosen as it is most commonly involved fuel in fire accidents. Fire simulations are performed by specifying two different boundary conditions: one the fuel is in liquid state and pyrolysis model is invoked, and the other by assuming the fuel is initially in a vapor state and thereby prescribing the mass loss rate. A domain of size 11.2 m × 11.2 m × 7.28 m with uniform structured grid is chosen for the numerical simulations. Grid sensitivity analysis is performed, and a non-dimensional grid size of 12 corresponding to 8 cm grid size is considered. Flame properties like mass burning rate, irradiance, and time-averaged axial flame temperature profile are predicted. The predicted steady-state mass burning rate is 40 g/s and is within the uncertainty limits of the previously reported experimental data (39.4 g/s). Though the profile of the irradiance at a distance from the fire along the height is somewhat in line with the experimental data and the location of the maximum value of irradiance is shifted to a higher location. This may be due to the lack of sophisticated models for the species transportation along with combustion and radiation in the continuous zone. Furthermore, the axial temperatures are not predicted well (for any of the boundary conditions) in any of the zones. The present study shows that the existing models are not sufficient enough for modeling blended fuels like diesel. The predictions are strongly dependent on the experimental values of the soot yield. Future experiments are necessary for generalizing the soot yield for different fires.

Keywords: burning rate, fire accidents, fire dynamic simulator, pyrolysis

Procedia PDF Downloads 197
4939 A 0-1 Goal Programming Approach to Optimize the Layout of Hospital Units: A Case Study in an Emergency Department in Seoul

Authors: Farhood Rismanchian, Seong Hyeon Park, Young Hoon Lee

Abstract:

This paper proposes a method to optimize the layout of an emergency department (ED) based on real executions of care processes by considering several planning objectives simultaneously. Recently, demand for healthcare services has been dramatically increased. As the demand for healthcare services increases, so do the need for new healthcare buildings as well as the need for redesign and renovating existing ones. The importance of implementation of a standard set of engineering facilities planning and design techniques has been already proved in both manufacturing and service industry with many significant functional efficiencies. However, high complexity of care processes remains a major challenge to apply these methods in healthcare environments. Process mining techniques applied in this study to tackle the problem of complexity and to enhance care process analysis. Process related information such as clinical pathways extracted from the information system of an ED. A 0-1 goal programming approach is then proposed to find a single layout that simultaneously satisfies several goals. The proposed model solved by optimization software CPLEX 12. The solution reached using the proposed method has 42.2% improvement in terms of walking distance of normal patients and 47.6% improvement in walking distance of critical patients at minimum cost of relocation. It has been observed that lots of patients must unnecessarily walk long distances during their visit to the emergency department because of an inefficient design. A carefully designed layout can significantly decrease patient walking distance and related complications.

Keywords: healthcare operation management, goal programming, facility layout problem, process mining, clinical processes

Procedia PDF Downloads 295
4938 Corporate Governance in Higher Education: A South African Perspective

Authors: Corlia van der Walt, Michele K. Havenga

Abstract:

The study considers corporate governance regulation and practice in South African higher education institutions and makes recommendations for the improvement of current governance practices in this sector. The development of corporate governance principles and practices in South Africa, culminating in the King IV Report on Corporate Governance which was launched in November 2016, is discussed. King IV enjoys international recognition as a progressive corporate governance instrument. It was necessitated by the fundamental changes in business and society nationally and globally, as well as by the significant changes to South African company law introduced by new legislation. Corporate governance and the corporate form are narrowly associated, but there is general recognition that the principles of ethical and effective leadership are not restricted to corporations. Thus King IV was drafted with the express aim that it should apply to all organisations, regardless of their form of incorporation, and the report includes specific sector supplements in support of this aspiration. The South African higher education sector has of late been under intense scrutiny, and a few universities have been placed under administration because of poor governance practices. Universities have also been severely impacted by the consequences of what is generally known as ‘#FeesmustFall’, a student led protest movement initially aimed against the increase of fees at public universities, but which rapidly expanded to also include other concerns. It was clearly necessary to revisit corporate governance policy and practice in the sector. The review of the current higher education governance regime in light of the King IV recommendations, lessons from company law regarding the entrenchment and enforcement of corporate governance principles, and a comparison of higher education governance practices in selected other jurisdictions led to recommendations for the improvement of governance practices in South African higher education. It is further suggested that a sector supplement for higher education institutions may provide additional clarity. Some of the recommendations may be of comparative value for international higher education governance.

Keywords: committees, corporate governance, ethical leadership, higher education institutions, integrated reporting, King IV, sector supplements, sustainability

Procedia PDF Downloads 409
4937 Thermal Ageing Effect on Mechanical Behavior of Polycarbonate

Authors: H. Babou, S. Ridjla, B. Amerate, R. Ferhoum, M. Aberkane

Abstract:

This work is devoted to the experimental study of thermal ageing effect on the mechanical and micro structural behavior of polycarbonate (PC). A simple compression tests, micro hardness and an IRTF analysis were completed in order to characterize the response of material on specimens after ageing at a temperature of order 100 C° and for serval maintain duration 72, 144 and 216 hours. These investigations showed a decrease of the intrinsic properties of polycarbonate (Young modulus, yield stress, etc.); the superposition of spectra IRTF shows that the intensity of chemical connections C=C, C-O, CH3 and C-H are influenced by the duration of thermal ageing; in addition, an increase of 30 % of micro hardness was detected after 216 hour of ageing.

Keywords: amorphous polymer, polycarbonate, mechanical behavior, compression test, thermal ageing

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4936 Antioxidant Extraction from Indonesian Crude Palm Oil and Its Antioxidation Activity

Authors: Supriyono, Sumardiyono, Puti Pertiwi

Abstract:

Crude palm oil (CPO) is a vegetable oil that came from a palm tree bunch. Palm oil tree was known as highest vegetable oil yield. It was grown across Equatorial County, especially in Malaysia and Indonesia. The greenish red color on CPO was came from carotenoid antioxidant, which could be extracted and use separately as functional food and other purposes as antioxidant source. Another antioxidant that also found in CPO is tocopherol. The aim of the research work is to find antioxidant activity on CPO comparing to the synthetic antioxidant that available in a market. On this research work, antioxidant was extracted by using a mixture of acetone and n. hexane, while activity of the antioxidant extract was determine by DPPH method. The extracted matter was shown that their antioxidant activity was about 45% compare to pure tocopherol and beta carotene.

Keywords: antioxidant, , beta carotene, , crude palm oil, , DPPH, , tocopherol

Procedia PDF Downloads 291
4935 Multi-Scale Modeling of Ti-6Al-4V Mechanical Behavior: Size, Dispersion and Crystallographic Texture of Grains Effects

Authors: Fatna Benmessaoud, Mohammed Cheikh, Vencent Velay, Vanessa Vidal, Farhad Rezai-Aria, Christine Boher

Abstract:

Ti-6Al-4V titanium alloy is one of the most widely used materials in aeronautical and aerospace industries. Because of its high specific strength, good fatigue, and corrosion resistance, this alloy is very suitable for moderate temperature applications. At room temperature, Ti-6Al-4V mechanical behavior is generally controlled by the behavior of alpha phase (beta phase percent is less than 8%). The plastic strain of this phase notably based on crystallographic slip can be hindered by various obstacles and mechanisms (crystal lattice friction, sessile dislocations, strengthening by solute atoms and grain boundaries…). The grains aspect of alpha phase (its morphology and texture) and the nature of its crystallographic lattice (which is hexagonal compact) give to plastic strain heterogeneous, discontinuous and anisotropic characteristics at the local scale. The aim of this work is to develop a multi-scale model for Ti-6Al-4V mechanical behavior using crystal plasticity approach; this multi-scale model is used then to investigate grains size, dispersion of grains size, crystallographic texture and slip systems activation effects on Ti-6Al-4V mechanical behavior under monotone quasi-static loading. Nine representative elementary volume (REV) are built for taking into account the physical elements (grains size, dispersion and crystallographic) mentioned above, then boundary conditions of tension test are applied. Finally, simulation of the mechanical behavior of Ti-6Al-4V and study of slip systems activation in alpha phase is reported. The results show that the macroscopic mechanical behavior of Ti-6Al-4V is strongly linked to the active slip systems family (prismatic, basal or pyramidal). The crystallographic texture determines which family of slip systems can be activated; therefore it gives to the plastic strain a heterogeneous character thus an anisotropic macroscopic mechanical behavior of Ti-6Al-4V alloy modeled. The grains size influences also on mechanical proprieties of Ti-6Al-4V, especially on the yield stress; by decreasing of the grain size, the yield strength increases. Finally, the grains' distribution which characterizes the morphology aspect (homogeneous or heterogeneous) gives to the deformation fields distribution enough heterogeneity because the crystallographic slip is easier in large grains compared to small grains, which generates a localization of plastic deformation in certain areas and a concentration of stresses in others.

Keywords: multi-scale modeling, Ti-6Al-4V alloy, crystal plasticity, grains size, crystallographic texture

Procedia PDF Downloads 157