Search results for: high pressure reactor

Authors: Fu Jinyu, Lin Jinguan

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This paper introduces a novel approach that unifies two types of models: one is the continuous-time jump-diffusion used to model high-frequency data, and the other is discrete-time GQARCH employed to model low-frequency financial data by embedding the discrete GQARCH structure with jumps in the instantaneous volatility process. This model is named “GQARCH-It\^{o} -Jumps mode.” We adopt the realized range-based threshold estimation for high-frequency financial data rather than the realized return-based volatility estimators, which entail the loss of intra-day information of the price movement. Meanwhile, a quasi-likelihood function for the low-frequency GQARCH structure with jumps is developed for the parametric estimate. The asymptotic theories are mainly established for the proposed estimators in the case of finite activity jumps. Moreover, simulation studies are implemented to check the finite sample performance of the proposed methodology. Specifically, it is demonstrated that how our proposed approaches can be practically used on some financial data.

Keywords: It\^{o} process, GQARCH, leverage effects, threshold, realized range-based volatility estimator, quasi-maximum likelihood estimate

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Authors: Y. Rae, A. Benaarbia, J. Hughes, Wei Sun

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This paper describes an elasto-visco-plastic computational modelling method which can be used to assess the cyclic plasticity responses of high temperature structures operating under thermo-mechanical loadings. The material constitutive equation used is an improved unified multi-axial Chaboche-Lemaitre model, which takes into account non-linear kinematic and isotropic hardening. The computational methodology is a three-dimensional framework following an implicit formulation and based on a radial return mapping algorithm. The associated user material (UMAT) code is developed and calibrated across isothermal hold-time low cycle fatigue tests for a typical turbine rotor steel for use in finite element (FE) implementation. The model is applied to a realistic industrial gas turbine rotor, where the study focuses its attention on the deformation heterogeneities and critical high stress areas within the rotor structure. The potential improvements of such FE visco-plastic approach are discussed. An integrated life assessment procedure based on R5 and visco-plasticity modelling, is also briefly addressed.

Keywords: unified visco-plasticity, thermo-mechanical, turbine rotor, finite element modelling

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Authors: Rupan Das Chakraborty, Surendra K. Martha

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Hard carbons (HCs) are extensively used as anode materials for sodium-ion batteries due to their availability, low cost, and ease of synthesis. It possesses the ability to store Na ion between stacked sp2 carbon layers and micropores. In this work, hard carbons are synthesized from different concentrations (0.5M to 5M) of dextrose solutions by hydrothermal synthesis followed by high-temperature calcination at 1100 ⁰C in an inert atmosphere. Dextrose has been chosen as a precursor material as it is a eco-friendly and renewable source. Among all hard carbon derived from different concentrations of dextrose solutions, hard carbon derived from 3M dextrose solution delivers superior electrochemical performance compared to other hard carbons. Hard carbon derived from 3M dextrose solution (Dextrose derived Hard Carbon-3M) provides an initial reversible capacity of 257 mAh g-1 with a capacity retention of 83 % at the end of 100 cycles at 30 mA g-1). The carbons obtained from different dextrose concentration show very similar Cyclic Voltammetry and chargedischarging behavior at a scan rate of 0.05 mV s-1 the Cyclic Voltammetry curve indicate that solvent reduction and the solid electrolyte interface (SEI) formation start at E < 1.2 V (vs Na/Na+). Among all 3M dextrose derived electrode indicate as a promising anode material for Sodium-ion batteries (SIBs).

Keywords: dextrose derived hard carbon, anode, sodium-ion battery, electrochemical performance

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Authors: Zoliana Bawitlung, P. C. Rohmingliana, L. Z. Chhangte, Remlal Siama, Hming Chungnunga, Vanram Lawma, L. Hnamte, B. K. Sahoo, B. K. Sapra, J. Malsawma

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Mizoram state has the highest lung cancer incidence rate in India due to its high-level consumption of tobacco and its products which is supplemented by the food habits. While smoking is mainly responsible for this incidence, the effect of inhalation of indoor radon gas cannot be discarded as the hazardous nature of this radioactive gas and its progenies on human population have been well-established worldwide where the radiation damage to bronchial cells eventually can be the second leading cause of lung cancer next to smoking. It is also known that the effect of radiation, however, small may be the concentration, cannot be neglected as they can bring about the risk of cancer incidence. Hence, estimation of indoor radon concentration is important to give a useful reference against radiation effects as well as establishing its safety measures and to create a baseline for further case-control studies. The indoor radon/thoron concentrations in Mizoram had been measured in 41 dwellings selected on the basis of spot gamma background radiation and construction type of the houses during 2015-2016. The dwellings were monitored for one year, in 4 months cycles to indicate seasonal variations, for the indoor concentration of radon gas and its progenies, outdoor gamma dose, and indoor gamma dose respectively. A time-integrated method using Solid State Nuclear Track Detector (SSNTD) based single entry pin-hole dosimeters were used for measurement of indoor Radon/Thoron concentration. Gamma dose measurements for indoor as well as outdoor were carried out using Geiger Muller survey meters. Seasonal variation of indoor radon/ thoron concentration was monitored. The results show that the annual average radon concentrations varied from 54.07 – 144.72 Bq/m³ with an average of 90.20 Bq/m³ and the annual average thoron concentration varied from 17.39 – 54.19 Bq/m³ with an average of 35.91 Bq/m³ which are below the permissible limit. The spot survey of gamma background radiation level varies between 9 to 24 µR/h inside and outside the dwellings throughout Mizoram which are all within acceptable limits. From the above results, there is no direct indication that radon/thoron is responsible for the high lung cancer incidence in the area. In order to find epidemiological evidence of natural radiations to high cancer incidence in the area, one may need to conduct a case-control study which is beyond this scope. However, the derived data of measurement will provide baseline data for further studies.

Keywords: background gamma radiation, indoor radon/thoron, lung cancer, seasonal variation

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Authors: Maoxin Ye

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This study examines the relationship between social network sites (SNS) usage and social capital. Because SNS usage can expand the users’ networks, and people who are connected in this networks may become resources to SNS users and lead them to advantage in some situation, it is important to estimate the relationship between SNS usage and ‘who’ is connected or what resources the SNS users can get. Additionally, ‘who’ can be divided in two aspects – people who possess high position and people who are different, hence, it is important to estimate the relationship between SNS usage and high position people and different people. This study adapts Lin’s definition of social capital and the measurement of position generator which tells us who was connected, and can be divided into the same two aspects as well. A national data of America (N = 2,255) collected by Pew Research Center is utilized to do a general regression analysis about SNS usage and social capital. The results indicate that SNS usage is negatively associated with each factor of social capital, and it suggests that, in fact, comparing with non-users, although SNS users can get more connections, the variety and resources of these connections are fewer. For this reason, we could lose benefits through SNS usage.

Keywords: social network sites, social capital, position generator, general regression

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Authors: Oliver Kinnane, Aidan Reilly, John Grimes, Sara Pavia, Rosanne Walker

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Unwanted sound reflection can create acoustic discomfort and lead to problems of speech comprehensibility. Contemporary building techniques enable highly finished internal walls resulting in sound reflective surfaces. In contrast, sustainable construction materials using natural and vegetal materials, are often more porous and absorptive. Hemp shiv is used as an aggregate and when mixed with lime binder creates a low-embodied-energy concrete. Cement replacements such as ground granulated blast slag (GGBS), a byproduct of other industrial processes, are viewed as more sustainable alternatives to high-embodied-energy cement. Hemp concretes exhibit good hygrothermal performance. This has focused much research attention on them as natural and sustainable low-energy alternatives to standard concretes. A less explored benefit is the acoustic absorption capability of hemp-based concretes. This work investigates hemp-lime-GGBS concrete specifically, and shows that it exhibits high levels of sound absorption.

Keywords: hemp, hempcrete, acoustic absorption, GGBS

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Authors: Rui Xing, Xiaowen Zhao, Hao Huang, Chang Liu

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Creativity is regarded as vital for new ventures' development since the whole process of entrepreneurship is rooted in the creation and exploration of new ideas. The entrepreneurial leader is central to the entrepreneurial team, who plays an especially important role in this process. However, few scholars have studied the impact entrepreneurs' leadership styles on the creativity of entrepreneurial teams. In this study, we integrate the historically disjointed literatures of leadership style and team creativity under entrepreneurship circumstance to understand why and when entrepreneurs' different leadership style relates to team creativity. Focus on answering the following questions: Is humility leadership necessarily better than narcissism leadership at increasing the creativity of entrepreneurial teams? Moreover, in which situations humility leadership or narcissism leadership is more conducive to the entrepreneurial team's creativity? Based on the componential theory of creativity and entrepreneurial cognition theory, we explore the relationship between entrepreneurs' leadership style and team creativity, treating team cognitive diversity and environmental uncertainty as moderators and psychological empowerment as mediators. We tested our hypotheses using data gathered from 64 teams and 256 individual members from 53 new firms in China's first-tier cities such as Beijing and Shanghai. We found that there was a significant positive relation between entrepreneurs' humble leadership and psychological empowerment, and the more significant the positive correlation was when the environmental uncertainty was high. In addition, there was a significant negative relation between entrepreneurs' narcissistic leadership and psychological empowerment, and the negative relation was weaker in teams with a high team cognitive diversity value. Furthermore, both entrepreneurs' humble leadership and team psychological empowerment were significantly positively related to team creativity. While entrepreneurs' narcissistic leadership was negatively related to team creativity, and the negative relationship was weaker in teams with a high team cognitive diversity or a high environmental uncertainty value. This study has some implications for both scholars and entrepreneurs. Firstly, our study enriches the understanding of the role of leadership in entrepreneurial team creativity. Different from previous team creativity literatures, focusing on TMT and R&D team, this study is a significant attempt to demonstrate that entrepreneurial leadership style is particularly relevant to the core requirements of team creativity. Secondly, this study introduces two moderating variables, cognitive diversity and environmental uncertainty, to explore the different boundary conditions under which the two leadership styles play their roles, which is helpful for entrepreneurs to understand how to leverage leadership to improve entrepreneurial team creativity, how to recruit cognitively diverse employees to moderate the effects of inappropriate leadership to the team. Finally, our findings showed that entrepreneurs' humble leadership makes a unique contribution to explaining team creativity through team psychological empowerment.

Keywords: entrepreneurs’ leadership style, entrepreneurial team creativity, team psychological empowerment, team cognitive diversity, environmental uncertainty

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Authors: Marion Francisco

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The study sought to investigate the psychological capital and work engagement of employees as predictors of employee performance in the technology industry in Makati City. It made used of a descriptive correlational method of research and utilized standardized tests, such as Psychological Capital Scale, Utrech Work Engagement Scale, and Employee Performance Scale. A convenience sampling technique was used to gather data samples from 100 populations with the help of Roscoe concept approach. The study revealed that both psychological capital and work engagement have a significant relationship with employee performance. Psychological capital and work engagement can predict employee performance of the respondents. With the results given, the study suggests: (1) to focus on maintaining a high level of psychological capital and work engagement, on achieving a very high level of psychological capital and work engagement, and on improving the low level of psychological capital or work engagement mostly during this COVID-19 pandemic using the proposed employee performance management plan and (2) to create a proposed employee performance management plan as necessary to tailor fit on employees needs to enhance their performance that will help meet company and client’s needs.

Keywords: employee performance, performance management, psychological capital, technology industry, work engagement

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Authors: Yu-Chen Chang, Yen-Ping Peng, Wei-Yu Chen, Ku-Fan Chen

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Contamination of soil and groundwater has become a serious and widespread environmental problem. In this study, sustained-release persulfate tablets were developed using persulfate powder and a modified cellulose binder for organic-contaminated groundwater remediation. Conventional cement-based persulfate-releasing materials were also synthesized for the comparison. The main objectives of this study were to: (1) evaluate the release rates of the remedial tablets; (2) obtain the optimal formulas of the tablets; and (3) evaluate the effects of the tablets on the subsurface environment. The results of batch experiments show that the optimal parameter for the preparation of the persulfate-releasing tablet was persulfate:cellulose = 1:1 (wt:wt) with a 5,000 kg F/cm2 of pressure application. The cellulose-based persulfate tablet was able to release 2,030 mg/L of persulfate per day for 10 days. Compared to cement-based persulfate-releasing materials, the persulfate release rates of the cellulose-based persulfate tablets were much more stable. Moreover, since the tablets are soluble in water, no waste will be produced in the subsurface. The results of column tests show that groundwater flow would shorten the release time of the tablets. This study successfully developed unique persulfate tablets based on green remediation perspective. The efficacy of the persulfate-releasing tablets on the removal of organic pollutants needs to be further evaluated. The persulfate tablets are expected to be applied for site remediation in the future.

Keywords: sustained-release persulfate tablet, modified cellulose, green remediation, groundwater

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Authors: Petros Gkotsis, Giorgos Stratidis, Manassis Mitrakas, Anastasios Zouboulis

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This study investigates the use of original and pre-polymerized iron (Fe) reagents compared to the commonly applied polyaluminum chloride (PACl) coagulant for surface water treatment. Applicable coagulants included both ferric chloride (FeCl₃) and ferric sulfate (Fe₂(SO₄)₃) and their pre-polymerized Fe reagents, such as polyferric sulfate (PFS) and polyferric chloride (PFCl). The efficiency of coagulants was evaluated by the removal of natural organic matter (NOM) and suspended solids (SS), which were determined in terms of reducing the UV absorption at 254 nm and turbidity, respectively. The residual metal concentration (Fe and Al) was also measured. Coagulants were added at five concentrations (1, 2, 3, 4 and 5 mg/L) and three pH values (7.0, 7.3 and 7.6). Experiments were conducted in a jar-test device, with two types of synthetic surface water (i.e., of high and low organic strength) which consisted of humic acid (HA) and kaolin at different concentrations (5 mg/L and 50 mg/L). After the coagulation/flocculation process, clean water was separated with filters of pore size 0.45 μm. Filtration was also conducted before the addition of coagulants in order to compare the ‘net’ effect of the coagulation/flocculation process on the examined parameters (UV at 254 nm, turbidity, and residual metal concentration). Results showed that the use of PACl resulted in the highest removal of humics for both types of surface water. For the surface water of high organic strength (humic acid-kaolin, 50 mg/L-50 mg/L), the highest removal of humics was observed at the highest coagulant dosage of 5 mg/L and at pH=7. On the contrary, turbidity was not significantly affected by the coagulant dosage. However, the use of PACl decreased turbidity the most, especially when the surface water of high organic strength was employed. As expected, the application of coagulation/flocculation prior to filtration improved NOM removal but slightly affected turbidity. Finally, the residual Fe concentration (0.01-0.1 mg/L) was much lower than the residual Al concentration (0.1-0.25 mg/L).

Keywords: coagulation/flocculation, iron and aluminum coagulants, metal salts, pre-polymerized coagulants, surface water treatment

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Authors: Angie Quevedo, Juan Bussi, Nestor Tancredi, Juan Fajardo-Díaz, Florentino López-Urías, Emilio Muñóz-Sandoval

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In this work, we study the carbon nanotubes (CNTs) formation by catalytic chemical vapor deposition (CCVD) over a catalyst with 20 % of Ni supported over La₂Zr₂O₇ (Ni20LZO). The high C solubility of Ni made it one of the most used in CNTs synthesis. Nevertheless, Ni presents also sintering and coalescence at high temperature. These troubles can be reduced by choosing a suitable support. We propose La₂Zr₂O₇ as for this matter since the incorporation of Ni by co-precipitation and calcination at 900 °C allows a good dispersion and interaction of the active metal (in the oxidized form, NiO) with this support. The CCVD was performed using 1 g of Ni20LZO at 950 °C during 30 min in Ar:H₂ atmosphere (2.5 L/min). The precursor, benzylamine, was added by a nebulizer-sprayer. X ray diffraction study shows the phase separation of NiO and La₂Zr₂O₇ after the calcination and the reduction to Ni after the synthesis. Raman spectra show D and G bands with a ID/IG ratio of 0.75. Elemental study verifies the incorporation of 1% of N. Thermogravimetric analysis shows the oxidation process start at around 450 °C. Future studies will determine the application potential of the samples.

Keywords: N doped carbon nanotubes, catalytic chemical vapor deposition, nickel catalyst, bimetallic oxide

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Authors: He Yuhai, Ahmad Ziad Bin Sulaiman

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Tongkat Ali, or Eurycoma longifolia, is a traditional Malay and Orang Asli herb used as aphrodisiac, general tonic, anti-Malaria, and anti-Pyretic. It has been recognized as a cashcrop by Malaysia due to its high value for the pharmaceutical use. In Tongkat Ali, eurycomanone, a quassinoid is usually chosen as a marker phytochemical as it is the most abundant phytochemical. In this research, ultrasound and enzyme were used to enhance the extraction of Eurycomanone from Tongkat Ali. Ultrasonic assisted extraction (USE) enhances extraction by facilitating the swelling and hydration of the plant material, enlarging the plant pores, breaking the plant cell, reducing the plant particle size and creating cavitation bubbles that enhance mass transfer in both the washing and diffusion phase of extraction. Enzyme hydrolyses the cell wall of the plant, loosening the structure of the cell wall, releasing more phytochemicals from the plant cell, enhancing the productivity of the extraction. Possible effects of ultrasound on the activity of the enzyme during the hydrolysis of the cell wall is under the investigation by this research. The extracts was analysed by high performance liquid chromatography for the yields of Eurycomanone. In this whole process, the conventional water extraction was used as a control of comparing the performance of the ultrasound and enzyme assisted extraction.

Keywords: ultrasound, enzymatic, extraction, Eurycoma longifolia

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Authors: Jihoon Lim, Patrick Kirchen, Ryozo Nagamune

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This paper proposes a linear parameter-varying (LPV) controller capable of reducing nitrogen oxide (NOx) emissions with low ammonia (NH3) slip downstream of selective catalytic reduction (SCR) systems. SCR systems are widely adopted in diesel engines due to high NOx conversion efficiency. However, the nonlinearity of the SCR system and sensor uncertainty result in a challenging control problem. In order to overcome the control challenges, an LPV controller is proposed based on gain-scheduling parameters, that is, exhaust gas temperature and exhaust gas flow rate. Based on experimentally obtained data under the non-road transient driving cycle (NRTC), the simulations firstly show that the proposed controller yields high NOx conversion efficiency with a desired low NH3 slip. The performance of the proposed LPV controller is then compared with other controllers, including a gain-scheduling PID controller and a sliding mode controller. Additionally, the robustness is also demonstrated using the uncertainties ranging from 10 to 30%. The results show that the proposed controller is robustly stable under uncertainties.

Keywords: diesel engine, gain-scheduling control, linear parameter-varying, selective catalytic reduction

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Authors: Folorunso Omoniyi, Peter Olubambi, Rotimi Sadiku

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Thermal barrier coating (TBC) system is used in both aero engines and other gas turbines to offer oxidation protection to superalloy substrate component. In the present work, it shows the ability of a new fabrication technique to develop rapidly new coating composition and microstructure. The compact powders were prepared by Powder Metallurgy method involving powder mixing and the bond coat was synthesized through the application of Spark Plasma Sintering (SPS) at 10500C to produce a fully dense (97%) NiCrAl bulk samples. The influence of sintering temperature on the hardness of NiCrAl, done by Micro Vickers hardness tester, was investigated. And Oxidation test was carried out at 1100oC for 20h, 40h, and 100h. The resulting coat was characterized with optical microscopy, scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDAX) and x-ray diffraction (XRD). Micro XRD analysis after the oxidation test revealed the formation of protective oxides and non-protective oxides.

Keywords: high-temperature oxidation, powder metallurgy, spark plasma sintering, thermal barrier coating

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Authors: Woei-Shyan Lee, Yu-Liang Chuang

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The nano-mechanical properties of as-deposited Cu/Si thin films indented to a depth of 2000 nm are investigated using a nanoindentation technique. The nanoindented specimens are annealed at a temperature of either 160 °C or 210°C, respectively. The microstructures of the as-deposited and annealed samples are then examined via transmission electron microscopy (TEM). The results show that both the loading and the unloading regions of the load-displacement curve are smooth and continuous, which suggests that no debonding or cracking occurs during nanoindentation. In addition, the hardness and Young’s modulus of the Cu/Si thin films are found to vary with the nanoindentation depth, and have maximum values of 2.8 GPa and 143 GPa, respectively, at the maximum indentation depth of 2000 nm. The TEM observations show that the region of the Cu/Si film beneath the indenter undergoes a phase transformation during the indentation process. In the case of the as-deposited specimens, the indentation pressure induces a completely amorphous phase within the indentation zone. For the specimens annealed at a temperature of 160°C, the amorphous nature of the microstructure within the indented zone is maintained. However, for the specimens annealed at a higher temperature of 210°C, the indentation affected zone consists of a mixture of amorphous phase and nanocrystalline phase. Copper silicide (η-Cu3Si) precipitates are observed in all of the annealed specimens. The density of the η-Cu3Si precipitates is found to increase with an increasing annealing temperature.

Keywords: nanoindentation, Cu/Si thin films, microstructural evolution, annealing temperature

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Authors: Izdihar Ismail, Alona C. Linatoc, Maryati Mohamed

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The tropical rainforest of Malaysia is known for its rich biological diversity and high endemicity. The potential for these forests to hold the cure for many diseases and illnesses is high and much is yet to be discovered. This study explores the richness of the tropical rainforest of Endau-Rompin National Park in Johor, Malaysia in search of plants traditionally used by the indigenous people in the treatment of malaria and malaria-like symptoms. Seven species of plants were evaluated and tested for antiplasmodial activities. Different plant parts were subjected to methanolic and aqueous extractions. A total of 24 extracts were evaluated by histidine-rich protein II (HRP2) assay against K1 strain of Plasmodium falciparum chloroquine-resistant. Ten extracts showed significant inhibition of the growth of P. falciparum. Phytochemical screening of the same extracts revealed the presence of alkaloids, flavonoids, terpenoids and anthraquinones. This study affirms that tropical rainforests may still hold undiscovered cures for many diseases and illnesses that have inflicted millions of people worldwide. The species studied herein have not known to have been studied elsewhere before.

Keywords: Endau-Rompin, malaria, Malaysia, tropical rainforest, traditional knowledge

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Authors: S. Ramia, N. Melhem, K. Kreidieh

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The world is facing an unprecedented displacement crisis. Recently, over 1.1 million asylum seekers have been granted protection status in the European Union (EU). The majority of these asylum seekers were from countries of the Middle East and North Africa (MENA) region.This influx carries with it a potential introduction of infectious diseases that have been eliminated in the EU, which poses a challenge for EU health authorities. Compared to MENA region countries where Hepatitis A Virus (HAV) endemicity is high to intermediate, member states of the EU show very low (Western Europe) to low (Eastern Europe) levels of HAV endemicity. Because of this situation, there is an ongoing public health concern in high-income countries, like members of the EU, that many adults remain susceptible to HAV outbreaks. The overwhelming majority of the EU members’ states do not include HAV vaccine in their immunization calendars. Hence, this paper urgently calls for the implementation of new policies regarding HAV in EU members’ states.

Keywords: European union, hepatitis A, MENA region refugees, vaccine preventable diseases

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Authors: Teagan Fink, Lynn Chong, Michael Hii, Brett Knowles

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Background: Telemedicine is a rapidly advancing field providing healthcare to patients at a distance from their treating clinician. There is a paucity of high-quality evidence detailing the safety and acceptability of telemedicine for postoperative outpatient follow-up. This randomized controlled trial – conducted prior to the COVID 19 pandemic – aimed to assess patient satisfaction and safety (as determined by readmission, reoperation and complication rates) of telephone compared to face-to-face clinic follow-up after uncomplicated general surgical procedures. Methods: Patients following uncomplicated laparoscopic appendicectomy or cholecystectomy and laparoscopic or open umbilical or inguinal hernia repairs were randomized to a telephone or face-to-face outpatient clinic follow-up. Data points including patient demographics, perioperative details and postoperative outcomes (eg. wound healing complications, pain scores, unplanned readmission to hospital and return to daily activities) were compared between groups. Patients also completed a Likert patient satisfaction survey following their consultation. Results: 103 patients were recruited over a 12-month period (21 laparoscopic appendicectomies, 65 laparoscopic cholecystectomies, nine open umbilical hernia repairs, six laparoscopic inguinal hernia repairs and two laparoscopic umbilical hernia repairs). Baseline patient demographics and operative interventions were the same in both groups. Patient or clinician-reported concerns on postoperative pain, use of analgesia, wound healing complications and return to daily activities at clinic follow-up were not significantly different between the two groups. Of the 58 patients randomized to the telemedicine arm, 40% reported high and 60% reported very high patient satisfaction. Telemedicine clinic mean consultation times were significantly shorter than face-to-face consultation times (telemedicine 10.3 +/- 7.2 minutes, face-to-face 19.2 +/- 23.8 minutes, p-value = 0.014). Rates of failing to attend clinic were not significantly different (telemedicine 3%, control 6%). There was no increased rate of postoperative complications in patients followed up by telemedicine compared to in-person. There were no unplanned readmissions, return to theatre, or mortalities in this study. Conclusion: Telemedicine follow-up of patients undergoing uncomplicated general surgery is safe and does not result in any missed diagnosis or higher rates of complications. Telemedicine provides high patient satisfaction and steps to implement this modality in inpatient care should be undertaken.

Keywords: general surgery, telemedicine, patient satisfaction, patient safety

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Authors: Klára Gajdošíková

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The aim of this study was to examine the quiet eye method and its components using the mobile eye tracking device. Quiet eye training was proven to be beneficial for different sports, including golf. The main idea of this method is to prolong your fixations on a specific place in order to improve your performance. The shot examined in this study is called putt. Its importance is based on its role on a golf course because, many times, it is the last putt that decides whether you win or lose. Quiet eye training helps players be more focused under pressure, control their attention and overall improve their putting success. Six highly skilled golfers with a handicap ranging from - 4 to + 4, aged 23 to 26, participated in a pilot study with the usage of an eye-tracking device. The study took place in an indoor training area at the golf club Hostivař. Crosstabs showed significant differences between individuals' laterality and their gaze into AOI - areas of interest (middle part of the ball, top of the ball, bottom of the ball, back side of the ball). Statistically significant differences were also discovered between the mean fixation duration of participants with AOI on the middle part of the ball and all other AOIs. The results of this study helped us understand the examined phenomena and showed us the next aim in future quiet eye research. Future research should focus on examining a quiet eye on the golf course. Applying a quiet eye and therefore changing the way we concentrate might be beneficial for coaches and players themselves.

Keywords: eye tracking, golf, laterality, quiet eye

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Authors: A. Kavandi, K. Goshtasbi, M. R. Hadei, H. Nejati

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In geothermal energy production, the method of liquid nitrogen (LN₂) fracturing in hot, dry rock is one of the most effective methods to increase the permeability of the reservoir. The geothermal reservoirs mainly consist of hard rocks such as granites and metamorphic rocks like gneiss with high temperatures. Gneiss, as a metamorphic rock, experiences a high level of inherent anisotropy. This type of anisotropy is considered as the nature of rocks, which affects the mechanical behavior of rocks. The aim of this study is to investigate the effects of heating-liquid nitrogen (LN₂) cooling treatment and rock anisotropy on the fracture toughness of gneiss. For this aim, a series of semi-circular bend (SCB) tests were carried out on specimens of gneiss with different anisotropy plane angles (0°, 30°, 60°, and 90°). In this study, gneiss specimens were exposed to heating–cooling treatment through gradual heating to 100°C followed by LN₂ cooling. Results indicate that the fracture toughness of treated samples is lower than that of untreated samples, and with increasing the anisotropy plane angle, the fracture toughness increases. The scanning electron microscope (SEM) technique is also implemented to evaluate the fracture process zone (FPZ) ahead of the crack tip.

Keywords: heating-cooling, anisotropic rock, fracture toughness, liquid nitrogen

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Authors: Bundit Pungnirund, Boonyada Pahasing

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The objective of this research is to study factors related to behaviors of Thai travelers traveling to Koh Kret Island, Nonthaburi Province. The subjects of this study included 400 Thai travelers coming to Koh Kred. Questionnaires were used to collect data which were analyzed by computer program to find mean and correlation coefficient by Pearson. The results showed that Thai travelers reported their opinions and attitudes in high level on the marketing service mix, product, price, place, promotion, personal, physical evidence, and process. They reported on travelling motivation factor, tourist attraction, and facility at high level. Moreover, marketing service mix, product, price, place, promotion, personal, physical, and process including travelling motivation factor, tourist attraction, and facility had positive relationship with the frequency in travelling at statistically significant level (0.01), though in a low relationship but in the same direction.

Keywords: factors, behaviors, Thai travelers, Koh Kled, Nonthaburi Province

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Authors: R. Kanmaniraja, R. Freshipali, J. Abdullah, K. Niranjan, K. Balasubramani, V. R. Sanal Kumar

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The present environmental issues have made aircraft jet noise reduction a crucial problem in aero-acoustics research. Acoustic studies reveal that addition of chevrons to the nozzle reduces the sound pressure level reasonably with acceptable reduction in performance. In this paper comprehensive numerical studies on acoustic characteristics of different types of chevron nozzles have been carried out with non-reacting flows for the shape optimization of chevrons in supersonic nozzles for aerospace applications. The numerical studies have been carried out using a validated steady 3D density based, k-ε turbulence model. In this paper chevron with sharp edge, flat edge, round edge and U-type edge are selected for the jet acoustic characterization of supersonic nozzles. We observed that compared to the base model a case with round-shaped chevron nozzle could reduce 4.13% acoustic level with 0.6% thrust loss. We concluded that the prudent selection of the chevron shape will enable an appreciable reduction of the aircraft jet noise without compromising its overall performance. It is evident from the present numerical simulations that k-ε model can predict reasonably well the acoustic level of chevron supersonic nozzles for its shape optimization.

Keywords: supersonic nozzle, Chevron, acoustic level, shape optimization of Chevron nozzles, jet noise suppression

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Authors: Bessy Thuranira

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Buildings, as they are designed and used, may contribute to serious environmental problems because of excessive consumption of energy and other natural resources. Buildings in the informal settlements particularly, due to their unplanned physical structure and design, have significantly contributed the global energy problematic scenario typified by high-level inefficiencies. Energy used in buildings in Africa is estimated to be the highest of the total national electricity consumption. Over the last decade, assessments of energy consumption and efficiency/inefficiency has focused on formal and modern buildings. This study seeks to go off the beaten path, by focusing on energy use in informal settlements. Operationally, it sought to establish the contribution of informal buildings in the overall energy consumption in the city and the country at large. This study was carried out in Mukuru kwa Reuben informal settlement where there is distinct manifestation of different settlement morphologies within a small locality. The research narrowed down to three villages (Mombasa, Kosovo and Railway villages) within the settlement, that were representative of the different slum housing typologies. Due to the unpredictability nature and informality in slums, this study takes a multi-methodology approach. Detailed energy audits and measurements are carried out to predict total building consumption, and document building design and envelope, typology, materials and occupancy levels. Moreover, the study uses semi-structured interviews and to access energy supply, cost, access and consumption patterns. Observations and photographs are also used to shed more light on these parameters. The study reveals the high energy inefficiencies in slum buildings mainly related to sub-standard equipment and appliances, building design and settlement layout, poor access and utilization/consumption patterns of energy. The impacts of this inefficiency are high economic burden to the poor, high levels of pollution, lack of thermal comfort and emissions to the environment. The study highlights a set of urban planning and building design principles that can be used to retrofit slums into more energy efficient settlements. The study explores principles of responsive settlement layouts/plans and appropriate building designs that use the beneficial elements of nature to achieve natural lighting, natural ventilation, and solar control to create thermally comfortable, energy efficient, and environmentally responsive buildings/settlements. As energy efficiency in informal settlements is a relatively less explored area of efficiency, it requires further research and policy recommendations, for which this paper will set a background.

Keywords: energy efficiency, informal settlements, renewable energy, settlement layout

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Authors: Azzeddine Atibi, Khadija El Kababi, Salim Ahmed, Mohamed Radid

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The principal objective of this study is to undertake a comprehensive comparative analysis of distance learning and blended learning modalities, with a particular emphasis on evaluating their effectiveness during the confinement period mandated by the COVID-19 pandemic. This investigation is rooted in the firsthand experiences of educators at the high school and secondary levels within both private and public educational institutions. To acquire the requisite data, we meticulously designed and distributed a survey to these educators, soliciting detailed narratives of their professional experiences throughout this challenging period. The survey aims to elucidate the specific difficulties encountered by teachers, as well as to highlight the innovative pedagogical strategies they devised in response to these challenges. By synthesizing the insights garnered from this survey, our goal is to foster an exchange of experiences among educators and to generate informed recommendations that will inform future educational reforms. Ultimately, this study aspires to contribute to the ongoing discourse on optimizing educational practices in the face of unprecedented disruptions.

Keywords: distance learning, blended learning, covid 19, secondary/ high school, teachingperformance, evaluation

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Authors: El-Said I. El-Shafey, Syeda Naheed F. Ali, Saleh S. Al-Busafi, Haider A. J. Al-Lawati

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Date palm leaflets were utilized as a precursor for activated carbon (AC) preparation using KOH activation. AC produced was oxidized using nitric acid producing oxidized activated carbon (OAC). OAC that possesses acidic surface was surface functionalized to produce basic activated carbons using linear diamine compounds (ethylene diamine and propylene diamine). OAC was also functionalized to produce hydrophobic activated carbons using ethylamine (EA) and aniline (AN). Dehydrated carbon was also prepared from date palm leaflets using sulfuric acid dehydration/ oxidation and was surface functionalized in the same way as AC. Nitric acid oxidation was not necessary for DC as it is acidic carbon. The surface area of AC is high (823 m2/g) with microporosity domination, however, after oxidation and surface functionalization, both the surface area and surface microporosity decrease tremendously. DC surface area was low (15 m2/g) with mesoporosity domination. Surface functionalization has decreased the surface area of activated carbons. FTIR spectra show that -COOH group on DC and OAC almost disappeared after surface functionalization. The surface chemistry of all carbons produced was tested for pHzpc, basic sites, boehm titration, thermogravimetric analysis and zeta potential measurement. Scanning electron microscopy and energy dispersive spectroscopy in addition to CHN elemental analysis were also carried out. DC and OAC possess low pHzpc and high surface functionality, however, basic and hydrophobic carbons possess high pHzpc and low surface functionality. The different behavior of carbons is related to their different surface chemistry. Methylene blue adsorption was found to be faster on hydrophobic carbons based on AC and DC. The Larger adsorption capacity of methylene blue was found for hydrophobic carbons. Dominating adsorption forces of methylene blue varies from carbon to another depending on its surface nature. Sorption forces include hydrophobic forces, H-bonding, electrostatic interactions and van der Waals forces.

Keywords: carbon, acidic, basic, hydrophobic

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Authors: P. Joshna, Souvik Kundu

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Detection of ultraviolet (UV) radiation is very important as it has exhibited a profound influence on humankind and other existences, including military equipment. In this work, a self-powered UV photodetector was reported based on oxides heterojunctions. The thin films of p-type nickel oxide (NiO) and n-type reduced graphene oxide (rGO) were used for the formation of p-n heterojunction. Low-Cost and low-temperature chemical synthesis was utilized to prepare the oxides, and the spin coating technique was employed to deposit those onto indium doped tin oxide (ITO) coated glass substrates. The top electrode platinum was deposited utilizing physical vapor evaporation technique. NiO offers strong UV absorption with high hole mobility, and rGO prevents the recombination rate by separating electrons out from the photogenerated carriers. Several structural characterizations such as x-ray diffraction, atomic force microscope, scanning electron microscope were used to study the materials crystallinity, microstructures, and surface roughness. On one side, the oxides were found to be polycrystalline in nature, and no secondary phases were present. On the other side, surface roughness was found to be low with no pit holes, which depicts the formation of high-quality oxides thin films. Whereas, x-ray photoelectron spectroscopy was employed to study the chemical compositions and oxidation structures. The electrical characterizations such as current-voltage and current response were also performed on the device to determine the responsivity, detectivity, and external quantum efficiency under dark and UV illumination. This p-n heterojunction device offered faster photoresponse and high on-off ratio under 365 nm UV light illumination of zero bias. The device based on the proposed architecture shows the efficacy of the oxides heterojunction for efficient UV photodetection under zero bias, which opens up a new path towards the development of self-powered photodetector for environment and health monitoring sector.

Keywords: chemical synthesis, oxides, photodetectors, spin coating

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Authors: Tokihiko Akita, Seiichi Mita

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A millimeter-wave radar is the most robust against adverse environments, making it an essential environment recognition sensor for automated driving. However, the reflection signal is sparse and unstable, so it is difficult to obtain the high recognition accuracy. Deep learning provides high accuracy even for them in recognition, but requires large scale datasets with ground truth. Specially, it takes a lot of cost to annotate for a millimeter-wave radar. For the solution, utilizing a simulator that can generate an annotated huge dataset is effective. Simulation of the radar is more difficult to match with real world data than camera image, and recognition by deep learning with higher-order features using the simulator causes further deviation. We have challenged to improve the accuracy of traffic participant classification by fusing simulator and real-world data with domain adaptation technique. Experimental results with the domain adaptation network created by us show that classification accuracy can be improved even with a few real-world data.

Keywords: millimeter-wave radar, object classification, deep learning, simulation, domain adaptation

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Authors: Rewati Raman, Uttam K. Roy

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One of the main adversaries of city planning in present times is the ever-expanding problem of urbanization and the antagonistic issues accompanying it. The prevalent challenges in urbanization such as population growth, urban sprawl, poverty, inequality, pollution, congestion, etc. call for reforms in the urban fabric as well as in planning theory and practice. One of the various paradigms of city planning, land use planning, has been the major instruments for spatial planning of cities and regions in India. Zoning regulation based land use planning in the form of land use and development control plans (LUDCP) and development control regulations (DCR) have been considered mainstream guiding principles in land use planning for decades. In spite of many advantages of such zoning based regulations, over a period of time, it has been critiqued by scholars for its own limitations of isolation and lack of vitality, inconvenience in business in terms of proximity to residence and low operating cost, unsuitable environment for small investments, higher travel distance for facilities, amenities and thereby higher expenditure, safety issues etc. Mixed land use has been advocated as a tool to avoid such limitations in city planning by researchers. In addition, mixed land use can offer many advantages like housing variety and density, the creation of an economic blend of compatible land use, compact development, stronger neighborhood character, walkability, and generation of jobs, etc. Alternatively, the mixed land use beyond a suitable balance of use can also bring disadvantages like traffic congestion, encroachments, very high-density housing leading to a slum like condition, parking spill out, non-residential uses operating on residential premises paying less tax, chaos hampering residential privacy, pressure on existing infrastructure facilities, etc. This research aims at studying and outlining the various challenges and potentials of mixed land use zoning, through modeling tools, as a competent instrument for city planning in lieu of the present urban scenario. The methodology of research adopted in this paper involves the study of a mixed land use neighborhood in India, identification of indicators and parameters related to its extent and spatial pattern and the subsequent use of system dynamics as a modeling tool for simulation. The findings from this analysis helped in identifying the various advantages and challenges associated with the dynamic nature of a mixed use urban settlement. The results also confirmed the hypothesis that mixed use neighborhoods are catalysts for employment generation, socioeconomic gains while improving vibrancy, health, safety, and security. It is also seen that certain challenges related to chaos, lack of privacy and pollution prevail in mixed use neighborhoods, which can be mitigated by varying the percentage of mixing as per need, ensuring compatibility of adjoining use, institutional interventions in the form of policies, neighborhood micro-climatic interventions, etc. Therefore this paper gives a consolidated and holistic framework and quantified outcome pertaining to the extent and spatial pattern of mixed land use that should be adopted to ensure sustainable urban planning.

Keywords: mixed land use, sustainable development, system dynamics analysis, urban dynamics modelling

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Authors: Sokkhey Phauk, Takeo Okazaki

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The challenging task in educational institutions is to maximize the high performance of students and minimize the failure rate of poor-performing students. An effective method to leverage this task is to know student learning patterns with highly influencing factors and get an early prediction of student learning outcomes at the timely stage for setting up policies for improvement. Educational data mining (EDM) is an emerging disciplinary field of data mining, statistics, and machine learning concerned with extracting useful knowledge and information for the sake of improvement and development in the education environment. The study is of this work is to propose techniques in EDM and integrate it into a web-based system for predicting poor-performing students. A comparative study of prediction models is conducted. Subsequently, high performing models are developed to get higher performance. The hybrid random forest (Hybrid RF) produces the most successful classification. For the context of intervention and improving the learning outcomes, a feature selection method MICHI, which is the combination of mutual information (MI) and chi-square (CHI) algorithms based on the ranked feature scores, is introduced to select a dominant feature set that improves the performance of prediction and uses the obtained dominant set as information for intervention. By using the proposed techniques of EDM, an academic performance prediction system (APPS) is subsequently developed for educational stockholders to get an early prediction of student learning outcomes for timely intervention. Experimental outcomes and evaluation surveys report the effectiveness and usefulness of the developed system. The system is used to help educational stakeholders and related individuals for intervening and improving student performance.

Keywords: academic performance prediction system, educational data mining, dominant factors, feature selection method, prediction model, student performance

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Authors: Salim Al Jadidi, Shian Gao, Shivananda Moolya

Abstract:

Computational Fluid Dynamic (CFD) technique coupled with Sub-Grid-Scale (SGS) model is used to study the flow behavior of heavy oil-water-air flow in a horizontal pipe by adapting ANSYS Fluent CFD software. The technique suitable for the transport of water-lubricated heavy viscous oil in a horizontal pipe is the Core Annular flow (CAF) technique. The present study focuses on the numerical study of CAF adapting Large Eddy Simulations (LES). The basic objective of the present study is to gain a basic knowledge of the flow behavior of heavy oil using turbulent CAF through a conventional horizontal pipe. This work also focuses on the success and applicability of LES. The simulation of heavy oil-water-air three-phase flow and two-phase flow of heavy oil–water in a conventional horizontal pipe is performed using ANSYS Fluent 16.2 software. The influence of three-phase heavy oil-water air flow in a selected pipe is affected by gravity. It is also observed from the result that the air phase and the variation in the temperature impact the behavior of the annular stream and pressure drop. Some results obtained during the study are validated with the results gained from part of the literature experiments and simulations, and the results show reasonably good agreement between the studies.

Keywords: computational fluid dynamics, gravity, heavy viscous oil, three-phase flow

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