Search results for: stability and performance

Authors: Daya Weerasinghe

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Parental expectations often differ to that of their children and the influence and involvement of parents, at home, may affect the student performance in the classroom. This paper presents results from a survey of Asian and European background secondary school mathematics students (N=128) in Melbourne, Australia. Student responses to survey questions were analysed using confirmatory factor analysis, followed by t-tests and ANOVA. The aim of the analysis was to identify similarities and differences in parental expectations in relation to ethnicity, gender, and the year level of the students. The notable findings from the analysis showed no significant difference (at 0.05 level) in parental expectations and student performance, in relation to ethnicity or gender. Conversely, there was a significant difference in both parental expectations and student performance between year 7 and year 12 students. Further, whilst there was a significant difference in parental expectations between year 7 and year 11 students, the students’ performances were not significantly different. The results suggest further research may be needed to understand the parental expectations and student performance between the lower and upper secondary school mathematics students.

Keywords: ethnic background, gender, parental expectations, student performance, year level

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Authors: Aleksandra Łochowicz, Daria Świętochowska, Loredano Pollegioni, Nazim Ocal, Franck Charmantray, Laurence Hecquet, Katarzyna Szymańska

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Multienzymatic cascade reactions are nowadays widely used in pharmaceutical, chemical and cosmetics industries to produce high valuable compounds. They can be carried out in two ways, step by step and one-pot. If two or more enzymes are in the same reaction vessel is necessary to work out the compromise to run the reaction in optimal conditions for each enzyme. So far most of the reports of multienzymatic cascades concern on usage of free enzymes. Unfortunately using free enzymes as catalysts of reactions accomplish high cost. What is more, free enzymes are soluble in solvents which makes reuse impossible. To overcome this obstacle enzymes can be immobilized what provides heterogeneity of biocatalyst that enables reuse and easy separation of the enzyme from solvents and reaction products. Usually, immobilization increase also the thermal and operational stability of enzyme. The advantages of using immobilized multienzymes are enhanced enzyme stability, improved cascade enzymatic activity via substrate channeling, and ease of recovery for reuse. The one-pot immobilized multienzymatic cascade can be carried out in mixed or coimmobilized type. When biocatalysts are coimmobilized on the same carrier the are in close contact to each other which increase the reaction rate and catalytic efficiency, and eliminate the lag time. However, in this type providing the optimal conditions both in the process of immobilization and cascade reaction for each enzyme is complicated. Herein, we examined immobilization of 3 enzymes: D-amino acid oxidase from Rhodotorula gracilis, commercially available catalase and transketolase from Geobacillus stearothermophilus. As a support we used silica monoliths with hierarchical structure of pores. Then we checked their stability and reusability in one-pot cascade of L-erythrulose and hydroxypuryvate acid synthesis.

Keywords: biocatalysts, enzyme immobilization, multienzymatic reaction, silica carriers

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Authors: Bassem Boshra Thabet, Mohammed Ibrahim Elsabagh, Mohammad Adly Talaat

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The number of cellular mobile phone users has increased enormously worldwide over the last two decades. Consequently, the monitoring of the performance of the Mobile Network Operators (MNOs) in terms of network coverage and broadband signal strength has become vital for both of the MNOs and regulators. This monitoring helps telecommunications operators and regulators keeping the market playing fair and most beneficial for users. However, the adopted methodologies to facilitate this continuous monitoring process are still problematic regarding cost, effort, and reliability. This paper introduces My Operator Coverage (MOC) system that is using Internet of Things (IoT) concepts and tools to monitor the MNOs performance using a crowd-sourced real-time methodology. MOC produces robust and reliable geographical maps for the user-perceived quality of the MNOs performance. MOC is also meant to enrich the telecommunications regulators with concrete, and up-to-date information that allows for adequate mobile market management strategies as well as appropriate decision making.

Keywords: mobile performance monitoring, crowd-sourced applications, mobile broadband performance, cellular networks monitoring

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Authors: Mahtab Davari, Charles Edward Okon, Somayeh Aghanavesi

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Every institute of learning is usually interested in the performance of enrolled students. The level of these performances determines the approach an institute of study may adopt in rendering academic services. The focus of this paper is to evaluate students' academic performance in given courses of study using machine learning methods. This study evaluated various supervised machine learning classification algorithms such as Logistic Regression (LR), Support Vector Machine, Random Forest, Decision Tree, K-Nearest Neighbors, Linear Discriminant Analysis, and Quadratic Discriminant Analysis, using selected features to predict study performance. The accuracy, precision, recall, and F1 score obtained from a 5-Fold Cross-Validation were used to determine the best classification algorithm to predict students’ performances. SVM (using a linear kernel), LDA, and LR were identified as the best-performing machine learning methods. Also, using the LR model, this study identified students' educational habits such as reading and paying attention in class as strong determinants for a student to have an above-average performance. Other important features include the academic history of the student and work. Demographic factors such as age, gender, high school graduation, etc., had no significant effect on a student's performance.

Keywords: student performance, supervised machine learning, classification, cross-validation, prediction

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Authors: Olayinka Ariba, Abe Oudshoorn, Steve Rolfe, Carrie Anne Marshall, Deanna Befus, Jason Gilliland, Miranda Crockett, Susana Caxaj, Sarah McLean, Amy Van Berkum, Natasha Thuemler

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Background: Secure housing is a platform for health and well-being. Those who struggle with housing stability have complex life and health histories and often require some support services such as the provision of permanent supportive housing. Poor access to supportive resources creates an exacerbation of chronic homelessness, particularly affecting individuals who need immediate access to mental health and addiction supports. This paper presents the first phase of a three-part study examining how on-site support impacts housing stability for recently-re-housed persons. Method: This study utilized a community-based participatory research methodology. Twenty in-depth interviews were conducted with permanent supportive housing residents from a single-site dwelling. Interpretative description analysis was used to draw common themes and understand the experiences and challenges of housing support. Results: Three interconnected themes were identified: 1) Available and timely supports; 2) Affordability; and 3) Community, but with independence as desired. These interconnected components are helping residents transition from homelessness or long-term mental health inpatient care to live in the community. Despite some participant concerns about resident conflicts, staff availability, and affordability, this has been a welcome and successful move for most. Conclusion: Supportive housing is essential for successful tenancies as a platform for health and well-being among Canada’s most vulnerable and, from the perspective of persons recently re-housed, permanent supportive housing is a worthwhile investment.

Keywords: homelessness, supportive housing, rehoused, housing stability

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Authors: M. S. Rodríguez, F. Cadaveira, M. F. Páramo

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First year university students comprise one of the groups most likely to indulge in hazardous alcohol consumption. The transition from secondary school to university presents a range of academic, social and developmental challenges requiring new responses that will meet the demands of this highly competitive environment. The main purpose of this research was to analyze the influence of gender and hazardous alcohol consumption on academic performance of 300 university students in Spain in a three-year follow-up study. Alcohol consumption was measured using the Alcohol Use Identification Test (AUDIT), and the average university grades were provided by the Academic Management Services of the University. Analysis of variance showed that the level of alcohol consumption significantly affected academic performance. Students undertaking hazardous alcohol consumption obtained the lowest grades during the first three years at university. These effects were particularly marked in the sample of women with a hazardous pattern of alcohol consumption, although the interaction between gender and this type of consumption was not significant. The study highlights the impact of hazardous alcohol consumption on the academic trajectory of university students. The findings confirm that alcohol consumption predicts poor academic performance in first year students and that the low level of performance is maintained throughout the university career.

Keywords: academic performance, alcohol consumption, gender, university students

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Authors: Karima Benfadel, Lamia Talbi, Sabiha Anas Boussaa, Afaf Brik, Assia Boukezzata, Yahia Ouadah, Samira Kaci

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In order to prevent global warming, which is mainly caused by the increase in carbon dioxide levels in the atmosphere, it is interesting to produce renewable energy in the form of chemical energy by converting carbon dioxide into alternative fuels and other energy-dense products. Photoelectrochemical reduction of carbon dioxide to value-added products and fuels is a promising and current method. The objective of our study is to develop Cu₂S-based photoélectrodes, in which Cu₂S is used as a CO₂ photoelectrocatalyst deposited on nanostructured silicon substrates. Cu₂S thin layers were deposited using the chemical bath deposition (CBD) technique. Silicon nanowires and nanopyramids were obtained by alkaline etching. SEM and UV-visible spectroscopy was used to analyse the morphology and optical characteristics. By using a potentiostat station, we characterized the photoelectrochemical properties. We performed cyclic voltammetry in the presence and without CO₂ purging as well as linear voltammetry (LSV) in the dark and under white light irradiation. We perform chronoamperometry to study the stability of our photocathodes. The quality of the nanowires and nanopyramids was visible in the SEM images, and after Cu₂S deposition, we could see how the deposition was distributed over the textured surfaces. The inclusion of the Cu₂S layer applied on textured substrates significantly reduces the reflectance (R%). The catalytic performance towards CO₂ conversion of Cu₂S/Si-based photocathodes revealed that the texturing of the silicon surface with nanowires and pyramids has a better photoelectrochemical behavior than those without surface modifications.

Keywords: CO₂ conversion, Cu₂S photocathode, silicone nanostructured, electrochemistry

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Authors: Fabrício José Piacente, Vanessa de Cillos Silva, Thiago Luiz Mello Melato

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The construction industry has been demonstrating increased growth and importance in Brazil’s national economic development. This study aims to evaluate the financial performance of the leading companies in the construction sector in Brazil in the period from 2009 to 2012. An analysis is made of the capital structure, liquidity, and profitability of the six largest companies in the construction sector in Brazil: Brookfield, Cyrela, Gafisa, MRV, PDG and Rossi. The results are then compared with standard industry ratios. It was found that among the companies analyzed, MRV and Cyrela showed the best relative performance in the period under consideration.

Keywords: accounting ratios, construction, financial performance, Brazil

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Authors: Alaa A. Ghanem, S. E. M. Desouky

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Natural gas (NG) is considered one of the most essential global energy sources. NG fields are often far away from the market, and a long-distance transporting pipeline usually is required. Production of NG with high content of CO₂ leads to severe problems such as equipment corrosion along with the production line until refinery.in addition to a high level of toxicity and decreasing in calorific value of the NG. So it is recommended to remove or decrease the CO₂ percent to meet transport specifications. This can be reached using different removal techniques such as physical and chemical absorption, pressure swing adsorption, membrane separation, or low-temperature separation. Many solvents and chemicals are being used to capture carbon dioxide on a large scale; among them, Ionic liquids have great potential due to their tunable properties; low vapour pressure, low melting point, and sensible thermal stability. In this research, three modifiedimidazolium ionic liquids will be synthesized and characterized using different tools of analysis such as FT-IR, 1H NMR. Thermal stability and surface activity will be studied. The synthesized compounds will be evaluated as selective solvents for CO₂ removal from natural gas using PVT cell.

Keywords: natural gas, CO₂ capture, imidazolium ionic liquid, PVT cell

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Authors: Chaoyi Sun, Congxin Chen, Yun Zheng, Kaizong Xia, Wei Zhang

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Crest loads are often encountered in hydropower, highway, open-pit and other engineering rock slopes. Toppling failure is one of the most common deformation failure types of anti-dip bedding rock slopes. Analysis on such failure of anti-dip bedding rock slopes subjected to crest loads has an important influence on engineering practice. Based on the step-by-step analysis approach proposed by Goodman and Bray, a geo-mechanical model was developed, and the related analysis approach was proposed for the toppling failure of anti-dip bedding rock slopes subjected to crest loads. Using the transfer coefficient method, a formulation was derived for calculating the residual thrust of slope toe and the support force required to meet the requirements of the slope stability under crest loads, which provided a scientific reference to design and support for such slopes. Through slope examples, the influence of crest loads on the residual thrust and sliding ratio coefficient was investigated for cases of different block widths and slope cut angles. The results show that there exists a critical block width for such slope. The influence of crest loads on the residual thrust is non-negligible when the block thickness is smaller than the critical value. Moreover, the influence of crest loads on the slope stability increases with the slope cut angle and the sliding ratio coefficient of anti-dip bedding rock slopes increases with the crest loads. Finally, the theoretical solutions and numerical simulations using Universal Distinct Element Code (UDEC) were compared, in which the consistent results show the applicability of both approaches.

Keywords: anti-dip bedding rock slope, crest loads, stability analysis, toppling failure

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Authors: Nirand Anunthanakul

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This paper is to investigate a 54-story reinforced concrete residential tall building structures—238.8 meters high. Shear walls, core walls, and columns are the primary vertical components. Other special lateral components—core-outrigger and belt trusses—are studied and combined with the structural system in order to increase the structural stability during severe lateral load events, particularly, wind loads. The wind tunnel tests are conducted using the force balance technique. The overall wind loads and dynamics response of the building are also measured for 360 degrees of azimuth—basis for 10-degree intervals. The results from numerical analysis indicate that an outrigger and belt truss system clearly engages perimeter columns to efficiently reduce acceleration index and lateral deformations at the top level so that the building structures achieve lateral stability, and meet standard provision values.

Keywords: outrigger, belt truss, tall buildings, wind loadings

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Authors: K. Soldatova, Y. Galerkin

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A loading factor performance is necessary for the modeling of centrifugal compressor gas dynamic performance curve. Measured loading factors are linear function of a flow coefficient at an impeller exit. The performance does not depend on the compressibility criterion. To simulate loading factor performances, the authors present two parameters: a loading factor at zero flow rate and an angle between an ordinate and performance line. The calculated loading factor performances of non-viscous are linear too and close to experimental performances. Loading factor performances of several dozens of impellers with different blade exit angles, blade thickness and number, ratio of blade exit/inlet height, and two different type of blade mean line configuration. There are some trends of influence, which are evident – comparatively small blade thickness influence, and influence of geometry parameters is more for impellers with bigger blade exit angles, etc. Approximating equations for both parameters are suggested. The next phase of work will be simulating of experimental performances with the suggested approximation equations as a base.

Keywords: loading factor performance, centrifugal compressor, impeller, modeling

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Authors: Hokuma Isgandarova, Khalil Aryanfar

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The patient's rights include all care items that the patient has the right to receive. Considering the growing importance of this important issue and its effect on improving treatment results and customer satisfaction, the present study was conducted with the aim of investigating the level of respect for patient rights in the physiotherapy clinic of the Faculty of Medicine University of Medical Sciences in 2023. In this study, the patients or companions who were referred to the clinic answered questions about the performance status of the clinic with respect to various aspects of the patient's rights. The aspects that were studied: choosing the service provider, having authority, respect, safety, prevention and access were found to have inappropriate performance scores. However, communication and interaction, continuity of service, quality of basic facilities and facilities, timely and immediate attention and trust had appropriate performance. Also, the results of the data analysis showed that there is no significant relationship between the total performance score and any of the demographic variables.

Keywords: compliance, patients' rights, physiotherapy clinic, performance level

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Authors: Ida Bagus Made Putra Jandhana, Teuku Yuri M. Zagloel, Rahmat Nurchayo

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Having several crises that affect industrial sector performance in the past decades, decision makers should utilize measurement application that enables them to measure industrial resiliency more precisely. It provides not only a framework for the development of resilience measurement application, but also several theories for the concept building blocks, such as performance measurement management, and resilience engineering in real world environment. This research is a continuation of previously published paper on performance measurement in the industrial sector. Finally, this paper contributes an alternative performance measurement method in industrial sector based on resilience concept. Moreover, this research demonstrates how applicable the concept of resilience engineering is and its method of measurement.

Keywords: industrial, measurement, resilience, sector

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Authors: Mohammad Bagher Hassanpouraghdam, Mohammad Ali Aazami Mavaloo

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Due to the huge side-effects of chemicals; essential oils have been considered as suitable alternatives for keeping the vase-life of cut flowers mainly owing to the availability and environment-friend nature of these bio-chemicals. In the present experiment, 50% substitution of STS was achieved and tested on cut carnation flowers cv. Liberty by using the essential oils from four plants; Satureja sahendica Bornm., Echinophora platyloba DC., Tanacetum balsamita L. and Cupressus arizonica Greene., as CRD with five treatments and 3 replications. Vase-life and flower diameter were affected with 50% substitution of STS by essential oils from C. arizonica and T. balsamita. Membrane stability index, Malondialdehyde (MDA) content and Hydrogen peroxide (H2O2) amounts were affected by the substitution treatments as well. The main preservative effect belonged to the substitution with C. arizonica. So that, 50% STS substitution with Cupressus oil holds the highest membrane integrity and the least data for MDA and H2O2 content.

Keywords: Carnation, essential oil, Membrane stability index (MSI), vase life

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Authors: Hieu Nguyen

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Performance management is the concern of any organizations in the context of increasing demand and fierce competition between education institution. This paper draws together the performance management concepts and focuses specifically to Balance Scorecard in the context of education. The study employs semi-structured in-depth interview to explore the measurement items for each of the sub-objectives in the four perspectives. Each of the perspectives’ explored measurement items will then be discussed the role and influence of them towards the perspective and how to improve the measurements to have improved performance management. Finally, the measurements will be put together as a suggested balanced scorecard framework in the case of International University.

Keywords: performance management, education institution, balance scorecard, measurement items, four perspectives, international univeristy

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Authors: Adebisi Moruf Ademola

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Hematite (Fe2O3),commonly known as ‘rust’ which usually surfaced on metal when exposed to some climatic materials. This emerges as a promising candidate for photoelectrochemical (PEC) water splitting due to its favorable physiochemical properties of the narrow band gap (2.1–2.2 eV), chemical stability, nontoxicity, abundance, and low cost. However, inherent limitations such as short hole diffusion length (2–4 nm), high charge recombination rate, and slow oxygen evolution reaction kinetics inhibit the PEC performances of a-Fe2O3 photoanodes. As such, given the narrow bandgap enabling excellent optical absorption, increased charge carrier density and accelerated surface oxidation reaction kinetics become the key points for improved photoelectrochemical performances for a-Fe2O3 photoanodes and metal ion doping as an effective way to promote charge transfer by increasing donor density and improving the electronic conductivity of a-Fe2O3. Hematite attracts enormous efforts with a number of metal ions (Ti, Zr, Sn, Pt ,etc.) as dopants. A facile deposition-annealing process showed greatly enhanced PEC performance due to the increased donor density and reduced electron-hole recombination at the time scale beyond a few picoseconds. Zr doping was also found to enhance the PEC performance of a-Fe2O3 nanorod arrays by reducing the rate of electron-hole recombination. Slow water oxidation reaction kinetics, another main factor limiting the PEC water splitting efficiency of aFe2O3 as photoanodes, was previously found to be effectively improved by surface treatment.

Keywords: deposition-annealing, hematite, metal ion doping, nanorod

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Authors: Ajay V. Kolhe, R. E. Shelke, S. S. Khandare

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This study discusses the performance and combustion characteristics of a direct injection diesel engine fueled with Jatropha methyl ester (JME). In order to determine the performance and combustion characteristics, the experiments were conducted at the constant speed mode (1500rpm) under the full load condition of the engine on single cylinder 4-stroke CI engine. The result indicated that when the test engine was fuelled with JME, the engine performance slightly weakened, the combustion characteristics slightly changed when compared to petroleum based diesel fuel. The biodiesel caused reduction in carbon monoxide (CO), unburned hydrocarbon (HC) emissions, but they caused to increases in nitrogen oxides (NOx) emissions. The useful brake power obtained is similar to diesel fuel for all loads. Oxygen content in the exhaust is more with JME blend due to the reason that fuel itself contains oxygen. JME as a new Biodiesel and its blends can be used in diesel engines without any engine modification.

Keywords: biodiesel, combustion, CI engine, jatropha curcas oil, performance and emission

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Authors: Salwa Aftab, Sehrish Riaz

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The objective of this study was to check the impact of grade sensitivity on learning motivation and academic performance of students and to remove the degree of difference that exists among students regarding the cause of their learning motivation and also to gain knowledge about this matter since it has not been adequately researched. Data collection was primarily done through the academic sector of Pakistan and was depended upon the responses given by students solely. A sample size of 208 university students was selected. Both paper and online surveys were used to collect data from respondents. The results of the study revealed that grade sensitivity has a positive relationship with the learning motivation of students and their academic performance. These findings were carried out through systematic correlation and regression analysis.

Keywords: academic performance, correlation, grade sensitivity, learning motivation, regression

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Authors: Vinay Choudhary, Ibakordor Patlong

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This study investigates and evaluates pre and post competitive anxiety, self-confidence, and performance of the athletes. The Cognitive State Anxiety Inventory-2 was administered to collect data from 73 athletes, both men, and women, before and after the competition, who participated in the Reliance Foundation Youth Sports (RFYS)-Athletics, held at Gachibowli Stadium, Hyderabad. A paired t-test was used to find the significant difference between the pre and post-competition. Results showed that the levels of cognitive state anxiety before the competition was low as compared after the competition and the levels of somatic state anxiety before the competition was high as compared after the competition whereas the levels of self-confidence before the competition was high as compared after the competition. This study concludes that the levels of cognitive state anxiety increases after the competition as athletes could not perform according to the performance expectations, on the contrary, the levels of somatic anxiety decrease as there was no pressure of performance on the athletes after the competition and the levels of self-confidence decreases after the competition as athletes could not reach their desired performance levels.

Keywords: anxiety, athletes, pre and post, CSAI-2, self-confidence, performance

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Authors: Mohammad Arif Sobhan Bhuiyan, Mamun Bin Ibne Reaz

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The rapid advancement of CMOS technology, in the recent years, has led the scientists to fabricate wireless transceivers fully on-chip which results in smaller size and lower cost wireless communication devices with acceptable performance characteristics. Moreover, the performance of the wireless transceivers rigorously depends on the performance of its first block T/R switch. This article proposes a design of a high performance T/R switch for 2.4 GHz RF wireless transceivers in 0.13 µm CMOS technology. The switch exhibits 1- dB insertion loss, 37.2-dB isolation in transmit mode and 1.4-dB insertion loss, 25.6-dB isolation in receive mode. The switch has a power handling capacity (P1dB) of 30.9-dBm. Besides, by avoiding bulky inductors and capacitors, the size of the switch is drastically reduced and it occupies only (0.00296) mm2 which is the lowest ever reported in this frequency band. Therefore, simplicity and low chip area of the circuit will trim down the cost of fabrication as well as the whole transceiver.

Keywords: CMOS, ISM band, SPDT, t/r switch, transceiver

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Authors: Shabnam Pashaei, Mohammadali Badamchizadeh

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This paper presents a new fractional-order terminal sliding mode control for synchronization of two different fractional-order chaotic systems with uncertainty and external disturbances. A fractional-order integral type nonlinear switching surface is presented. Then, using the Lyapunov stability theory and sliding mode theory, a fractional-order control law is designed to synchronize two different fractional-order chaotic systems. Finally, a simulation example is presented to illustrate the performance and applicability of the proposed method. Based on numerical results, the proposed controller ensures that the states of the controlled fractional-order chaotic response system are asymptotically synchronized with the states of the drive system.

Keywords: terminal sliding mode control, fractional-order calculus, chaotic systems, synchronization

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Authors: Mojtaba Ghodsi, Morteza Mohammadzaheri, Payam Soltani

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This study provides a detailed analysis of the LTC3588 as a low-power energy storage model, focusing on its internal circuitry and energy harvesting capabilities. The study highlights the relationship between the input and output capacitors and the behavior of the output voltage, particularly its rise time. It was found that increasing the input capacitance (Cᵢₙ) from 1 µF to 220 µF reduces oscillations in the output voltage (Vₒᵤₜ) and slows the rate of increase in the input voltage, demonstrating the impact of input capacitance on voltage dynamics. Furthermore, the study revealed that smaller output capacitors (Cₒᵤₜ) result in fewer voltage jumps required to reach the target output voltage of 3.2 V, suggesting that a smaller Cₒᵤₜ improves voltage regulation speed and stability. The study concludes that both input and output capacitors play a critical role in the LTC3588's performance. Optimizing these capacitors is crucial for efficient energy storage and harvesting in applications requiring minimal power consumption.

Keywords: LTC3588, modeling, Zener diode, LED

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Authors: Md. Belal Uudin Rabbi, Sakib Al Montasir, Saifur Rahman, Niger Nahid, Esmail Hossain Emon

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The practice of radiation shielding protects against the detrimental effects of ionizing radiation. Radiation shielding depletes radiation by inserting a shield of absorbing material between any radioactive source. It is a primary concern when building several industrial fields, so using potent (high activity) radioisotopes in food preservation, cancer treatment, and particle accelerator facilities is significant. Radiation shielding is essential for radiation-emitting equipment users to reduce or mitigate radiation damage. Polymer composites (especially epoxy based) with high atomic number fillers can replace toxic Lead in ionizing radiation shielding applications because of their excellent mechanical properties, superior solvent and chemical resistance, good dimensional stability, adhesive, and less toxic. Due to being lightweight, good neutron shielding ability in almost the same order as concrete, epoxy-based radiation shielding can be the next big thing. Micro and nano-particles for the epoxy resin increase the epoxy matrix's radiation shielding property. Shielding is required to protect users of such facilities from ionizing radiation as recently, and considerable attention has been paid to polymeric composites as a radiation shielding material. This research will examine the radiation shielding performance of epoxy-based nano-WO3 reinforced composites, exploring the performance of epoxy-based nano-WO3 reinforced composites. The samples will be prepared using the direct pouring method to block radiation. The practice of radiation shielding protects against the detrimental effects of ionizing radiation.

Keywords: radiation shielding materials, ionizing radiation, epoxy resin, Tungsten oxide, polymer composites

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Authors: Wilman Septina, Rajiv R. Prabhakar, Thomas Moehl, David Tilley

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Cupric oxide (CuO) is a promising absorber material for the fabrication of scalable, low cost solar energy conversion devices, due to the high abundance and low toxicity of copper. It is a p-type semiconductor with a band gap of around 1.5 eV, absorbing a significant portion of the solar spectrum. One of the main challenges in using CuO as solar absorber in an aqueous system is its tendency towards photocorrosion, generating Cu2O and metallic Cu. Although there have been several reports of CuO as a photocathode for hydrogen production, it is unclear how much of the observed current actually corresponds to H2 evolution, as the inevitability of photocorrosion is usually not addressed. In this research, we investigated the effect of the deposition of overlayers onto CuO thin films for the purpose of enhancing its photostability as well as performance for water splitting applications. CuO thin film was fabricated by galvanic electrodeposition of metallic copper onto gold-coated FTO substrates, followed by annealing in air at 600 °C. Photoelectrochemical measurement of the bare CuO film using 1 M phosphate buffer (pH 6.9) under simulated AM 1.5 sunlight showed a current density of ca. 1.5 mA cm-2 (at 0.4 VRHE), which photocorroded to Cu metal upon prolonged illumination. This photocorrosion could be suppressed by deposition of 50 nm-thick TiO2, deposited by atomic layer deposition. In addition, we found that insertion of an n-type CdS layer, deposited by chemical bath deposition, between the CuO and TiO2 layers was able to enhance significantly the photocurrent compared to without the CdS layer. A photocurrent of over 2 mA cm-2 (at 0 VRHE) was observed using the photocathode stack FTO/Au/CuO/CdS/TiO2/Pt. Structural, electrochemical, and photostability characterizations of the photocathode as well as results on various overlayers will be presented.

Keywords: CuO, hydrogen, photoelectrochemical, photostability, water splitting

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Authors: Moeen Naseer Butt

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Clustering –geographic concentrations of entities– has recently received more attention in marketing research and has been shown to affect multiple outcomes. This study investigates the impact of intrabrand clustering (clustering of same-brand outlets) on an outlet’s quality performance. Further, it assesses the moderating effects of interbrand clustering (clustering of other-brand outlets) and firm size. An examination of approximately 21,000 food service establishments in New York State in 2019 finds that the impact of intrabrand clustering on an outlet’s quality performance is context-dependent. Specifically, intrabrand clustering decreases, whereas interbrand clustering and firm size help increase the outlet’s performance. Additionally, this study finds that the role of firm size is more substantial than interbrand clustering in mitigating the adverse effects of intrabrand clustering on outlet quality performance.

Keywords: intraband clustering, interbrand clustering, firm size, brand competition, outlet performance, quality violations

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Authors: Yumei Wang, Xiaoyu Xu, Li Lu

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Solid-state battery adopts solid-state electrolyte such as oxide- and composite-based solid electrolytes. With the adaption of nonflammable or less flammable solid electrolytes, the safety of solid-state batteries can be largely increased. NASICON (Na₃Zr₂Si₂PO₁₂, NZSP) is one of the sodium ion conductors that possess relatively high ionic conductivity, wide electrochemical stable range and good chemical stability. Therefore, it has received increased attention. We report the development of high-density NZSP through liquid phase sintering and its organic-inorganic composite electrolyte. Through reactive liquid phase sintering, the grain boundary conductivity can be largely enhanced while using an organic-inorganic composite electrolyte, interfacial wetting and impedance can be largely reduced hence being possible to fabricate scalable solid-state batteries.

Keywords: solid-state electrolyte, composite electrolyte, electrochemical performance, conductivity

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Authors: Marlene Perez Villalpando, Kelly Joel Gurubel Tun

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In this paper, we propose an optimal control strategy for a hydroelectric power plant subject to input disturbances like meteorological phenomena. The engineering characteristics of the system are described by a nonlinear model. The random availability of renewable sources is predicted by a high-order neural network trained with an extended Kalman filter, whereas the power generation is regulated by the optimal control law. The main advantage of the system is the stabilization of the amount of power generated in the plant. A control supervisor maintains stability and availability in hydropower reservoirs water levels for power generation. The proposed approach demonstrated a good performance to stabilize the reservoir level and the power generation along their desired trajectories in the presence of disturbances.

Keywords: hydropower, high order neural network, Kalman filter, optimal control

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Authors: Klas Elmquist, Anders Larsson

Abstract:

Until the year 2000, almost all short pulse modulators in the accelerator world were made with the pulse forming network (PFN) technique. The pulse forming network systems have since then been replaced with solid state modulators that have better efficiency, better stability, and lower cost of ownership, and they are much smaller. In this paper, it is shown that it is possible to replace a pulse forming network system with a solid-state system without changing the klystron tank and the klystron transformer. The solid-state modulator uses semiconductors switching at 1 kV level. A first pulse transformer transforms the voltage up to 10 kV. The 10 kV pulse is finally fed into the original transformer that is placed under the klystron. A flatness of 0.8 percent and stability of 100 PPM is achieved. The test is done with a CPI 8262 type of klystron. It is also shown that it is possible to run such a system with long cables between the transformers. When using this technique, it will be possible to keep original sub-systems like filament systems, vacuum systems, focusing solenoid systems, and cooling systems for the klystron. This will substantially reduce the cost of an upgrade and prolong the life of the klystron system.

Keywords: modulator, solid-state, PFN-system, thyratron

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Authors: Rasheed O. Oloyede, Joseph O. Adelusi, Peter O. Akinbile

Abstract:

This study was conducted to investigate the extent with which knowledge of results influences the performance of cricket players. A sample of 160 fresh students in the Department of Physical and Health Education who are novice in the game were randomly assigned into two groups. The first group of eighty (80) subjects was classified as experimental group while the second group of eighty (80) subjects was the control group. Subjects in both groups were asked to bowl and bat ten times each for a period of six weeks. After the first round, the subjects in the experimental group were allowed feedback on their performance in the first trial while those in the control group were denied feedback. Two null hypotheses generated for the study were tested using percentages and chi-square statistical analysis at 0.05 level of significance. Analysis of data showed that knowledge of results influenced the performance of cricket players. It was concluded that knowledge of results is pertinent for effective skill acquisition and could enhance better performance among unskilled cricket players. Hence, it is suggested that immediate feedback on the level of skill acquisition by the prospective and unskilled cricket players would inspire them for better performance in cricket tournaments.

Keywords: batting, bowling, knowledge of results, performance, skill acquisition

Procedia PDF Downloads 472