Search results for: circular regression

Authors: Minhal Abidi, Moinuddin

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Diabetes mellitus (DM) induced metabolic abnormalities causes oxidative stress which leads to the pathogenesis of complications associated with diabetes like retinopathy, nephropathy periodontitis etc. Combination of glycation and oxidation 'glycoxidation' occurs when oxidative reactions affect the early state of glycation products. Low density lipoprotein (LDL) is prone to glycoxidative attack by sugars and methylglyoxal (MGO) being a strong glycating agent may have severe impact on its structure and consequent role in diabetes. Pro-inflammatory cytokines like IL1β and TNFα produced by the action of gram negative bacteria in periodontits (PD) can in turn lead to insulin resistance. This work discusses modifications to LDL as a result of glycoxidation. The changes in the protein molecule have been characterized by various physicochemical techniques and the immunogenicity of the modified molecules was also evaluated as they presented neo-epitopes. Binding of antibodies present in diabetes patients to the native and glycated LDL has been evaluated. Role of modified epitopes in the generation of antibodies in diabetes and periodontitis has been discussed. The structural perturbations induced in LDL were analyzed by UV–Vis, fluorescence, circular dichroism and FTIR spectroscopy, molecular docking studies, thermal denaturation studies, Thioflavin T assay, isothermal titration calorimetry, comet assay. MALDI-TOF, ketoamine moieties, carbonyl content and HMF content were also quantitated in native and glycated LDL. IL1β and TNFα levels were also measured in the type 2 DM and PD patients. We report increased carbonyl content, ketoamine moieties and HMF content in glycated LDL as compared to native analogue. The results substantiate that in hyperglycemic state MGO modification of LDL causes structural perturbations making the protein antigenic which could obstruct normal physiological functions and might contribute in the development of secondary complications in diabetic patients like periodontitis.

Keywords: advanced glycation end products, diabetes mellitus, glycation, glycoxidation, low density lipoprotein, periodontitis

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Authors: Phillip F. Blaauw, Anna M. Pretorius

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South Africa re-entered the international economy in the early 1990s, after Apartheid, at a time when globalisation was gathering momentum. Globalisation led to a more open economy, increased export volumes and a changed export mix. Manufacturing goods gained ground relative to mining products. After 21 years of democracy, South African researchers and policymakers need to evaluate the impact of international trade on the level of employment and compensation of employees in the South African manufacturing industry. This is important given the consistent and high levels of unemployment in South Africa. This paper has this evaluation as its aim. Two complimenting approaches are utilised. The 27 sub divisions of the South African manufacturing industry are classified according to capital/labour ratios. Possible trends in employment levels and employee compensation for these categories are then identified when comparing levels in 1995 to those in 2014. The supplementing empirical approach is cross-sectional and panel data regressions for the same period. The aim of the regression analysis is to explain the observed changes in employment and employee compensation levels between 1995 and 2014. The first part of the empirical approach revealed that over the 20-year period the intermediate capital intensive, labour intensive an ultra-labour intensive manufacturing industries all showed massive declines in overall employment. Only three of the 19 industries for these classifications showed marginal overall employment gains. The only meaningful gains were recorded in three of the eight capital intensive manufacturing industries. The overall performance of the South African manufacturing industry is therefore dismal at best. This scenario plays itself out for the skilled section of the intermediate capital intensive, labour intensive an ultra-labour intensive manufacturing industries as well. 18 out of the 19 industries displayed declines even for the skilled section of the labour force. The formal regression analysis supplements the above results. Real production growth is a statistically significant (95 per cent confidence level) explanatory variable of the overall employment level for the period under consideration, albeit with a small positive coefficient. The variables with the most significant negative relationship with changes in overall employment were the dummy variables for intermediate capital intensive and labour intensive manufacturing goods. Disaggregating overall changes in employment further in terms of skill levels revealed that skilled employment in particular responded negatively to increases in the ratio between imported and local inputs for manufacturing. The dummy variable for the labour intensive sectors remained negative and statistically significant, indicating that the labour intensive sectors of South African manufacturing remain vulnerable to the loss of employment opportunities. Whereas the first period (1995 to 2001) after the opening of the South African economy brought positive changes for skilled employment, continued increases in imported inputs displaced some of the skilled labour as well, putting further pressure on the South African economy with already high and persistent unemployment levels. Given the negative for the world commodity cycle and a stagnant local manufacturing sector, the challenge for policymakers is getting even more pronounced after South Africa’s political coming of age.

Keywords: capital/labour ratios, employment, employee compensation, manufacturing

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Authors: Anam Bhatti, Sumbal Arif, Mariam Mehar, Sohail Younas

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CSR has become one of the imperative implements in satisfying customers. The impartial of this research is to calculate CSR, relationship marketing, and customer satisfaction. In Pakistan, there is not enough research work on the effect of CSR and relationship marketing on relationship maintainer and customer loyalty. To find out deductive approach and survey method is used as research approach and research strategy respectively. This research design is descriptive and quantitative study. For data, collection questionnaire method with semantic differential scale and seven point scales are adopted. Data has been collected by adopting the non-probability convenience technique as sampling technique and the sample size is 400. For factor confirmatory factor analysis, structure equation modeling and medication analysis, regression analysis Amos software were used. Strong empirical evidence supports that the customer’s perception of CSR performance is highly influenced by the values.

Keywords: CSR, Relationship marketing, Relationship maintainer, Customer loyalty, Customer satisfaction

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Authors: Sungroul Kim, Yeonjin Kim

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This study was conducted by comparing the concentrations of heavy metals analyzed from the same samples with three X-Ray fluorescence (XRF) spectrometer in three different global research institutions, including PAN (A Branch of Malvern Panalytical, Seoul, South Korea), RTI (Research Triangle Institute, NC, U.S.A), and aerosol laboratory in Harvard University, Boston, U.S.A. To achieve our research objectives, the indoor air filter samples were collected at homes (n=24) of adults or child asthmatics then analyzed in PAN followed by Harvard University and RTI consecutively. Descriptive statistics were conducted for data comparison as well as correlation and simple regression analysis using R version 4.0.3. As a result, detection rates of most heavy metals analyzed in three institutions were about 90%. Of the 25 elements commonly analyzed among those institutions, 16 elements showed an R² (coefficient of determination) of 0.7 or higher (10 components were 0.9 or higher). The findings of this study demonstrated that XRF was a useful device ensuring reproducibility and compatibility for measuring heavy metals in PM2.5 collected from indoor air of asthmatics’ home.

Keywords: heavy metals, indoor air quality, PM2.5, X-ray fluorescence

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Authors: Hasan Kaya

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Effect of lead content on the microstructure, mechanical (microhardness, ultimate tensile strength) and electrical resistivity properties of Al–Si eutectic alloys has been investigated. Al–12.6 Si–xSn (x=1, 2, 4, 6 and 8 wt. %) were prepared using metals of 99.99% high purity in the vacuum atmosphere. These alloys were directionally solidified under constant temperature gradient (5.50 K/mm) and growth rate (8.25 μm/s) by using a Bridgman–type directional solidification furnace. Eutectic spacing, microhardness, ultimate tensile strength and electrical resistivity were expressed as functions of the composition by using a linear regression analysis. The dependency of the eutectic spacing, microhardness, tensile strength and electrical resistivity on the composition (Sn content) were determined. According to experimental results, the microhardness, ultimate tensile strength and electrical resistivity of the solidified samples increase with increasing the Sn content, but decrease eutectic spacing. Variation of electrical resistivity with the temperature in the range of 300-500 K for studied alloys was also measured by using a standard d.c. four-point probe technique.

Keywords: content elements, solidification, microhardness, strength

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Authors: Mohammad Tahir Yousafzai, Rubina Qasim

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We assessed Hepatitis B vaccination and its determinants among health care workers (HCW) in Northwest Pakistan. HCWs from both public and private clinics were interviewed about hepatitis B vaccination, socio-demographic, hepatitis B virus transmission modes, disease threat and benefits of vaccination. Logistic regression was performed. Hepatitis B vaccination was 40% (Qualified Physicians: 86% and non-qualified Dispensers:16%). Being Qualified Physician (Adj. OR 26.6; 95%CI 9.3-73.2), Non-qualified Physician (Adj.OR 1.9; 95%CI 0.8-4.6), qualified Dispensers (Adj. OR 3.6; 95%CI 1.3-9.5) compared to non-qualified Dispensers, working in public clinics (Adj. OR 2.5; 95%CI 1.1-5.7) compared to private, perceived disease threat after exposure to blood and body fluids (Adj. OR 1.1; 95%CI 1.1-1.2) and perceived benefits of vaccination (Adj. OR 1.1; 95%CI 1.1-1.2) were significant predictors of hepatitis B vaccination. Improved perception of disease threat and benefits of vaccination and qualification of HCWs are associated with hepatitis B vaccination.

Keywords: Hepatitis B vaccine, immunization, healthcare workers, primary health

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Authors: Rakesh Prajapati, Purvik Patel, Hardik Patel

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Productivity and quality are two important aspects that have become great concerns in today’s competitive global market. Every production/manufacturing unit mainly focuses on these areas in relation to the process, as well as the product developed. The electrical discharge machining (EDM) process, even now it is an experience process, wherein the selected parameters are still often far from the maximum, and at the same time selecting optimization parameters is costly and time consuming. Material Removal Rate (MRR) during the process has been considered as a productivity estimate with the aim to maximize it, with an intention of minimizing surface roughness taken as most important output parameter. These two opposites in nature requirements have been simultaneously satisfied by selecting an optimal process environment (optimal parameter setting). Objective function is obtained by Regression Analysis and Analysis of Variance. Then objective function is optimized using Genetic Algorithm technique. The model is shown to be effective; MRR and Surface Roughness improved using optimized machining parameters.

Keywords: MMR, TWR, OC, DOE, ANOVA, minitab

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Authors: Jungyeol Hong, Dongjoo Park

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The urban transit system is a critical part of a solution to the economic, energy, and environmental challenges. Furthermore, it ultimately contributes the improvement of people’s quality of lives. For taking these kinds of advantages, the city of Seoul has tried to construct an integrated transit system including both subway and buses. The effort led to the fact that approximately 6.9 million citizens use the integrated transit system every day for their trips. Diagnosing the current transit network is a significant task to provide more convenient and pleasant transit environment. Therefore, the critical objective of this study is to establish a methodological framework for the analysis of an integrated bus-subway network and to examine the relationship between subway ridership and parameters such as network topology measures, bus demand, and a variety of commercial business facilities. Regarding a statistical approach to estimate subway ridership at a station level, many previous studies relied on Ordinary Least Square regression, but there was lack of studies considering the endogeneity issues which might show in the subway ridership prediction model. This study focused on both discovering the impacts of integrated transit network topology measures and endogenous effect of bus demand on subway ridership. It could ultimately contribute to developing more accurate subway ridership estimation accounting for its statistical bias. The spatial scope of the study covers Seoul city in South Korea, and it includes 243 subway stations and 10,120 bus stops with the temporal scope set during twenty-four hours with one-hour interval time panels each. The subway and bus ridership information in detail was collected from the Seoul Smart Card data in 2015 and 2016. First, integrated subway-bus network topology measures which have characteristics regarding connectivity, centrality, transitivity, and reciprocity were estimated based on the complex network theory. The results of integrated transit network topology analysis were compared to subway-only network topology. Also, the non-recursive approach which is Three-Stage Least Square was applied to develop the daily subway ridership model as capturing the endogeneity between bus and subway demands. Independent variables included roadway geometry, commercial business characteristics, social-economic characteristics, safety index, transit facility attributes, and dummies for seasons and time zone. Consequently, it was found that network topology measures were significant size effect. Especially, centrality measures showed that the elasticity was a change of 4.88% for closeness centrality, 24.48% for betweenness centrality while the elasticity of bus ridership was 8.85%. Moreover, it was proved that bus demand and subway ridership were endogenous in a non-recursive manner as showing that predicted bus ridership and predicted subway ridership is statistically significant in OLS regression models. Therefore, it shows that three-stage least square model appears to be a plausible model for efficient subway ridership estimation. It is expected that the proposed approach provides a reliable guideline that can be used as part of the spectrum of tools for evaluating a city-wide integrated transit network.

Keywords: integrated transit system, network topology measures, three-stage least squared, endogeneity, subway ridership

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Authors: Shady Gamal Aziz Shehata

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Difficulty in defining construction quality arises due to perception based on the nature and requirements of the market, the different partners themselves and the results they want. Quantitative research was used in this constructivist research. A case-based study was conducted to assess the structures of positive attitudes and expectations in the context of quality improvement. A survey based on expert opinions was analyzed among construction organizations/companies operating in the construction industry in Pakistan. The financial strength, management structure and construction experience of the construction companies formed the basis of their selection. A good concept is visible at the project level and is seen as the most valuable part of the construction project. Each quality improvement technique was expected to increase the user's profits by improving the efficiency of the construction project. The Survey is useful for construction professionals to evaluate current construction concepts and expectations for the application of quality improvement techniques in construction projects.

Keywords: correlation analysis, lean construction tools, lean construction, logistic regression analysis, risk management, safety construction quality, expectation, improvement, perception

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Authors: Rosita Kanapeckaite

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Every year, some candidates who enroll in Generolas Jonas Zemaitis Military Academy of Lithuania do not complete a basic seven weeks cadet course and leave the Academy. Experience in other countries shows that psychological resilience grit and intrinsic motivation can lead to better course completion results. We examined the psychological resilience grit and intrinsic motivation as predictors of better results among newcomers who participate in the Cadet Basic Training (CBT) course. Based on past research and theory of other countries' military academies, we expected that resilience grit, and intrinsic motivation would predict performance in the Cadet Basic Training course. Results of regression analyses revealed that resilience and grit can predict better course results, but intrinsic motivation can not predict retention. These findings suggest that resilience and grit assessment and training may prove valuable in enhancing performance and retention within military training environments.

Keywords: military, intrinsic motivation, grit, resilience

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Authors: Ali Mohammed Yimer, Ayalew Assen, Youssef Belmabkhout

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Environmental remediation is a pressing global concern, necessitating innovative strategies to address the challenges posed by industrial waste and pollution. This study aims to advance environmental remediation by developing cutting-edge functional porous materials from phosphorite residue tailings. Phosphorite mining activities generate vast amounts of waste, which pose significant environmental risks due to their contaminants. The proposed approach involved transforming these phosphorite residue tailings into valuable porous materials through a series of physico-chemical processes including milling, acid-base leaching, designing or templating as well as formation processes. The key components of the tailings were extracted and processed to produce porous arrays with high surface area and porosity. These materials were engineered to possess specific properties suitable for environmental remediation applications, such as enhanced adsorption capacity and selectivity for target contaminants. The synthesized porous materials were thoroughly characterized using advanced analytical techniques (XRD, SEM-EDX, N2 sorption, TGA, FTIR) to assess their structural, morphological, and chemical properties. The performance of the materials in removing various pollutants, including heavy metals and organic compounds, were evaluated through batch adsorption experiments. Additionally, the potential for material regeneration and reusability was investigated to enhance the sustainability of the proposed remediation approach. The outdoors of this research holds significant promise for addressing the environmental challenges associated with phosphorite residue tailings. By valorizing these waste materials into porous materials with exceptional remediation capabilities, this study contributes to the development of sustainable and cost-effective solutions for environmental cleanup. Furthermore, the utilization of phosphorite residue tailings in this manner offers a potential avenue for the remediation of other contaminated sites, thereby fostering a circular economy approach to waste management.

Keywords: functional porous materials, phosphorite residue tailings, adsorption, environmental remediation, sustainable solutions

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Authors: Andrey V. Timofeev, Dmitry V. Egorov

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The practical efficient approach is suggested for estimation of the seismoacoustic sources energy in C-OTDR monitoring systems. This approach represents the sequential plan for confidence estimation both the seismoacoustic sources energy, as well the absorption coefficient of the soil. The sequential plan delivers the non-asymptotic guaranteed accuracy of obtained estimates in the form of non-asymptotic confidence regions with prescribed sizes. These confidence regions are valid for a finite sample size when the distributions of the observations are unknown. Thus, suggested estimates are non-asymptotic and nonparametric, and also these estimates guarantee the prescribed estimation accuracy in the form of the prior prescribed size of confidence regions, and prescribed confidence coefficient value.

Keywords: nonparametric estimation, sequential confidence estimation, multichannel monitoring systems, C-OTDR-system, non-lineary regression

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Authors: Daniela Tapusi, Adrian Andronic, Naomi Tufan, Ruxandra Erbașu, Ioana Teodorescu

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The proposed theme of this article falls within the policy of reducing carbon emissions imposed by the ‘Green New Deal’ by replacing structural elements made of energy-intensive materials with ecological materials. In this sense, wood has many qualities (high strength/mass and stiffness/mass ratio, low specific gravity, recovery/recycling) that make it competitive with classic building materials. The topological optimization of the linear glulam elements, resulting from different types of analysis (Finite Element Method, simple regression on metamodels), tests on models or by Monte-Carlo simulation, leads to a material reduction of more than 10%. This article proposes a method of obtaining topologically optimized shapes for different types of glued laminated timber beams. The results obtained will constitute the database for AI training.

Keywords: timber, glued laminated timber, artificial-intelligence, environment, carbon emissions

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Authors: Faisal Mahroogi, Mahmoud Bady, Yaser H. Alahmadi, Ahmed Alsisi, Sunny Narayan, Muhammad Usman Kaisan

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The Kingdom of Saudi Arabia established Saudi Vision 2030, an initiative of the government with the goal of promoting more socioeconomic as well as cultural diversity. The kingdom, which is dedicated to sustainable development and clean energy, uses cutting-edge approaches to address energy-related issues, including the circular carbon economy (CCE) and a more varied energy mix. In order for Saudi Arabia to achieve its Vision 2030 goal of having a net zero future by 2060, sustainability is essential. By addressing the energy and climate issues of the modern world with responsibility and innovation, Vision 2030 is turning into a global role model for the transition to a sustainable future. As per the Ambitions of the National Environment Strategy of the Saudi Ministry of Environment, Agriculture, and Water (MEWA), raising environmental compliance across all sectors and reducing pollution and adverse environmental impacts are critical focus areas. As a result, the current study presents an experimental analysis of the performance and exhaust emissions of a diesel engine running mostly on waste cooking oil (WCO). A one-cylinder direct-injection diesel engine with constant speed and natural aspiration is the engine type utilized. Research was done on how the engine performed and emission parameters when fueled with a mixture of 10% butanol, 10% diesel, 10% WCO, and 10% diethyl ether (D70B10W10DD10). The study's findings demonstrated that engine emissions of nitrogen oxides (NOX) and carbon monoxide (CO) varied significantly depending on the load being applied. The brake thermal efficiency, cylinder pressure, and the brake power of the engine were all impacted by load change.

Keywords: ICE, waste cooking oil, fuel additives, butanol, combustion, emission characteristics

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Authors: Petr Květon, Martin Jelínek

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We try to identify the role of various aspects of parenting style in the phenomenon of videogame playing addiction. Relevant self-report questionnaires were part of a wider set of methods focused on the constructs related to videogame playing. The battery of methods was administered in school settings in paper and pencil form. The research sample consisted of 333 (166 males, 167 females) elementary and high school students at the age between 10 and 19 years (m=14.98, sd=1.77). Using stepwise regression analysis, we assessed the influence of demographic variables (gender and age) and parenting styles. Age and gender together explained 26.3% of game addiction variance (F(2,330)=58.81, p<.01). By adding four aspect of parenting styles (inconsistency, involvement, control, and warmth) another 10.2% of variance was explained (∆F(4,326)=13.09, p<.01). The significant predictor was gender of the respondent, where males scored higher on game addiction scale (B=0.70, p<.01), age (β=-0.18, p<.01), where younger children showed higher level of addiction, and parental inconsistency (β=0.30, p<.01), where the higher the inconsistency in upbringing, the more developed game playing addiction.

Keywords: gender, parenting styles, video games, addiction

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Authors: M. D. D. Chathurangi, M. G. K. Nayanathara, K. M. H. M. M. Gunapala, G. M. R. G. Dayananda, Kavinga Yapa Abeywardena, Deemantha Siriwardana

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Due to the growing popularity of social media platforms at present, there are various concerns, mostly cyberbullying, spam, bot accounts, and the spread of incorrect information. To develop a risk score calculation system as a thorough method for deciphering and exposing unethical social media profiles, this research explores the most suitable algorithms to our best knowledge in detecting the mentioned concerns. Various multiple models, such as Naïve Bayes, CNN, KNN, Stochastic Gradient Descent, Gradient Boosting Classifier, etc., were examined, and the best results were taken into the development of the risk score system. For cyberbullying, the Logistic Regression algorithm achieved an accuracy of 84.9%, while the spam-detecting MLP model gained 98.02% accuracy. The bot accounts identifying the Random Forest algorithm obtained 91.06% accuracy, and 84% accuracy was acquired for fake news detection using SVM.

Keywords: cyberbullying, spam behavior, bot accounts, fake news, machine learning

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Authors: Abderrahmen Aloulou, Younes Boujelbene

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The current paper displays a new method of extracting information content from options prices by eliminating biases caused by daily variation of contract maturity. Based on Kernel regression tool, this non-parametric technique serves to obtain a spectrum of interpolated options with constant maturity horizons from negotiated optional contracts on the S&P TSX 60 index. This method makes it plausible to compare daily risk neutral densities from which extracting time continuous indicators allows the detection traders attitudes’ evolution, such as, belief homogeneity, asymmetry and extreme Risk Perception. Our findings indicate that the applied method contribute to develop effective trading strategies and to adjust monetary policies through controlling trader’s reactions to economic and monetary news.

Keywords: risk neutral densities, kernel, constant maturity horizons, homogeneity, asymmetry and extreme risk perception

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Authors: Yang Yi-Fei, Luo Min-Zhou, Zhang Fu-Chun, He Nai-Bao, Xing Shao-Bang

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This paper presents an electromagnetic finite element model of permanent magnet synchronous linear motor and distortion rate of the air gap flux density waveform is analyzed in detail. By designing the sample space of the parameters, nonlinear regression modeling of the orthogonal experimental design is introduced. We put forward for possible air gap flux density waveform sine electromagnetic scheme. Parameters optimization of the permanent magnet synchronous linear motor is also introduced which is based on chaotic search and adaptation function. Simulation results prove that the pole shifting does not affect the motor back electromotive symmetry based on the structural parameters, it provides a novel way for the optimum design of permanent magnet synchronous linear motor and other engineering.

Keywords: permanent magnet synchronous linear motor, finite element analysis, chaotic search, optimization design

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Authors: Shama Urooj

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The present work investigates the relationship among financial inclusion, modernization, and energy performance in SCO member countries during the years 2011–2021. PCA is used to create composite indexes of financial inclusion, modernization, and energy performance. We used panel regression models that are both reliable and heteroscedasticity-consistent to look at the relationship among variables. The findings indicate that financial inclusion (FI) and modernization, along with the increased FDI, all appear to contribute to the energy performance in the SCO member countries. However, per capita GDP has a negative impact on energy performance. These results are unbiased and consistent with the robust results obtained by applying different econometric models. Feasible Generalized Least Square (FGLS) estimation is also used for checking the uniformity of the main model results. This research work concludes that there has been no policy coherence in SCO member countries regarding the coordination of growing financial inclusion and modernization for energy sustainability in recent years. In order to improve energy performance with modern development, policies regarding financial inclusion and modernization need be integrated both at national as well as international levels.

Keywords: financial inclusion, energy performance, modernization, technological development, SCO.

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Authors: Amaba, Marinela C., Espino, Gianne Ericka S. J. Valencia, Zeia Beatriz C.

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This study aims to determine the moderating role of attachment style on the relationship between psychological symptoms and well-being of mental health practitioners in rehabilitation centers that are accredited of the Department of Health in Pampanga. Using the data gathered from 46 mental health practitioners, multiple regression models were conducted to test the main and moderating effects of attachment styles. The findings show that all three psychological symptoms namely depression, anxiety, and stress have main effects on their general well-being on a negative direction. However, attachment style did not moderate the relationship between the psychological symptoms and general well-being. On one hand, results about the relationship of psychological symptoms and well-being are consistent to previous findings of other studies while on the other hand, results in moderation were contradicting.

Keywords: attachment style, psychological symptoms, well-being, mental health practitioners, rehabilitation centers

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Authors: Mahmoud M. Tash

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The present study was carried out to investigate the effect of alloying elements and thermo-mechanical treatment (TMT) i.e. hot rolling and forging with different reduction ratios on the hardness (HV) and impact toughness (J) of heat-treated low alloy steels. An understanding of the combined effect of TMT and alloying elements and by measuring hardness, impact toughness, resulting from different heat treatment following TMT of the low alloy steels, it is possible to determine which conditions yielded optimum mechanical properties and high strength to weight ratio. Experimental Correlations between hot work reduction ratio, hardness and impact toughness for thermo-mechanically heat treated low alloy steels are analyzed quantitatively, and both regression and mathematical hardness and impact toughness models are developed.

Keywords: hot forging, hot rolling, heat treatment, hardness (HV), impact toughness (J), microstructure, low alloy steels

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Authors: Lin-Lin Liu, Song-Qi Hu, Yin Wang

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Paraffin-based fuels are regarded to be a promising fuel of hybrid rocked motor because of the high regression rate, low price, and environmental friendliness. Graphene Oxide (GO) is an attractive energetic material which is expected to be widely used in propellants, explosives, and some high energy fuels. Paraffin-based fuels with paraffin and GO as raw materials were prepared, and the oxidation process of the samples was investigated by thermogravimetric analysis differential scanning calorimetry (TG/DSC) under oxygen (O₂) and nitrous oxide (N₂O) atmospheres. The oxidation reaction kinetics of the fuels was estimated through the non-isothermal measurements and model-free isoconversional methods based on the experimental results of TGA. The results show that paraffin-based fuels are easier oxidized under O₂ rather than N₂O with atmospheres due to the lower activation energy; GO plays a catalytic role for the oxidation of paraffin-based fuels under the both atmospheres, and the activation energy of the oxidation process decreases with the increase of GO; catalytic effect of GO on the oxidation of paraffin-based fuels are more obvious under O₂ atmospheres than under N₂O atmospheres.

Keywords: graphene oxide, paraffin-based fuels, oxidation, activation energy, TGA

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Authors: Apolinar Picado, Ronald Solís, Rafael Gamero

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The thin-layer drying characteristics of instant coffee solution were investigated in a laboratory tunnel dryer. Drying experiments were carried out at three temperatures (80, 100 and 120 °C) and an air velocity of 1.2 m/s. Drying experimental data obtained are fitted to six (6) thin-layer drying models using the non-linear least squares regression analysis. The acceptability of the thin-layer drying model has been based on a value of the correlation coefficient that should be close to one, and low values for root mean square error (RMSE) and chi-square (x²). According to this evaluation, the most suitable model for describing drying process of thin-layer instant coffee solution is the Page model. Further, the effective moisture diffusivity and the activation energy were computed employing the drying experimental data. The effective moisture diffusivity values varied from 1.6133 × 10⁻⁹ to 1.6224 × 10⁻⁹ m²/s over the temperature range studied and the activation energy was estimated to be 162.62 J/mol.

Keywords: activation energy, diffusivity, instant coffee, thin-layer models

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Authors: Cristina Lopes, Alan C. Mix

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The timing and extension of large discharges from glacial lakes, known as megafloods, into the oceans have been of key importance. This type of events can influence the oceanic/land interactions and even be related with climate changes. While the impact of such floods has been fairly studied in the North Atlantic, the impact of analog floods in the North Pacific remains debatable and relatively unknown. Here we will show records of the Missoula floods that have carved the Northwest landscape and have entered the North Pacific through the Columbia River. These records are given by the presence of high (more than 40%) percentages of freshwater diatoms in marine sediments. A regression equation using these percentages allows to estimate by how much the salinities decreased. The timing and impact of North Pacific megafloods recorded in three marine cores of Oregon and California for the past 25000 years (B.P.) will be presented. These records show that the volume of freshwater that entered the North Pacific reached as far as 600 Km south of the Columbia River Mouth, decreasing the salinities by as much as 4 units.

Keywords: diatoms, megafloods, Missoula, North Pacific

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Authors: Shunhong Qi, Hui Tian

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Triggered off by the forthcoming 2022 Winter Olympics, ski centers are blossoming in China, the number being 742 in 2018. Although the number of skier visits of ski resorts soared to 19.7 million in 2018, one-time skiers account for a considerable portion therein. In light of the extremely low return rates and skiing penetration level (0.5%) of leisure skiing in China, this study proposes and tests a leisure ski service performance framework which assesses the ski resorts’ service quality, skier satisfaction, as well as their impact on skiers’ behavioral intentions, with an aim to assess the success of ski resorts and provide suggestions for improvement. Three self-administered surveys and 16 interviews were conducted upon a convenience sample of leisure skiers in two major ski destinations within two hours’ drive from Beijing – Nanshan and Jundushan ski resorts. Of the 680 questionnaires distributed, 416 usable copies were returned, the response rate being 61.2%. The questionnaire used for the study was developed based on the existing literature of 'push' factors of skiers (intrinsic desire) and 'pull' factors (attractiveness of a destination), as well as leisure sport satisfaction. The scale comprises four parts: skiers’ demographic profiles, their perceived service quality (including ski resorts’ infrastructure, expense, safety and comfort, convenience, daily needs support, skill development support, and accessibility), their overall levels of satisfaction (satisfaction with the service and the experience), and their behavioral intentions (including loyalty, future visitation and greater tolerance of price increases). Skiers’ demographic profiles show that among the 220 males and 196 females in the survey, a vast majority of the skiers are age 17-39 (87.2%). 64.7% are not married, and nearly half (48.3%) of the skiers have a monthly family income exceeding 10,000 yuan (USD 1,424), and 80% are beginners or intermediate skiers. The regression examining the influence of service quality on skier satisfaction reveals that service quality accounts for 44.4% of the variance in skier satisfaction, the variables of safety and comfort, expense, skill development support, and accessibility contributing significantly in descending order. Another regression analyzing the influence of service quality as well as skier satisfaction on their behavioral intentions shows that service quality and skier satisfaction account for 39.1% of the variance in skiers’ behavioral intentions, and the significant predictors are skier satisfaction, safety and comfort, expense, and accessibility, in descending order, though a comparison between groups also indicates that for expert skiers, the significant variables are skier satisfaction, skill development support, safety, and comfort. Suggestions are thus made for ski resorts and other stakeholders to improve skier satisfaction and increase visitation: developing diversified ski courses to meet the demands of skiers of different skiing skills and to reduce crowding, adopting enough chairlifts and magic carpets, reinforcing safety measures and medical force; further exploring their various resources and lower the skiing expense on ski pass, equipment renting, accommodation and dining; adding more bus lines and/or develop platforms for skiers’ car-pooling, and offering diversified skiing activities with local flavors for better entertainment.

Keywords: behavioral intentions, leisure skiing, service quality, skier satisfaction

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Authors: Huy Q. Tran, Jungwon Huh, Kiseok Kwak, Choonghyun Kang

Abstract:

Infrared thermography (IRT) technique has been proven to be a good method for nondestructive evaluation of concrete material. In the building, a broad range of applications has been used such as subsurface defect inspection, energy loss, and moisture detection. The purpose of this research is to consider the qualitative and quantitative performance of reinforced concrete deteriorations using active infrared thermography technique. An experiment of three different heating regimes was conducted on a concrete slab in the laboratory. The thermal characteristics of the IRT method, i.e., absolute contrast and observation time, are investigated. A linear relationship between the observation time and the real depth was established with a well linear regression R-squared of 0.931. The results showed that the absolute contrast above defective area increases with the rise of the size of delamination and the heating time. In addition, the depth of delamination can be predicted by using the proposal relationship of this study.

Keywords: concrete building, infrared thermography, nondestructive evaluation, subsurface delamination

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Authors: Suvimon Wajeetongratana, Prateep Wajeetongratana

Abstract:

The purpose of this research will study the organizational behavior including self-efficacy, hope, optimism, and resiliency that affect to the work motivation in the Dusit workplace and the sample consisted of the production workers in a private company in Dusit area for four hundred workers with approximately 10,000 employees and in this study will provide the multiple regression analysis was used to analyze the questionnaire survey data. The results of the analysis indicate the latent core confidence factor derived from the four components of self-efficacy, hope, optimism, and resiliency provided a significant positive impact on performance. The impact of the integrated latent core confidence factor was, in fact, more effective than derived from any one individual component, as well as any core trait-like self-evaluations such as self-esteem, general efficacy, internal locus of control, and emotional stability.

Keywords: firm performance effectiveness, organizational behavior, work motivation, Dusit workplace

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Authors: Li Zhang, Yuehong Su

Abstract:

Lightpipe as a mature solar light tube technique has been employed worldwide. Accurately assessing the performance of lightpipe and evaluate daylighting available has been a challenging topic. Previous research had used regression model and computational simulation methods to estimate the performance of lightpipe. However, due to the nonlinear nature of solar light transferring in lightpipe, the methods mentioned above express inaccurate and time-costing issues. In the present study, a neural network model as an alternative method is investigated to predict the transmittance of lightpipe. Four types of commercial lightpipe with bended angle 0°, 30°, 45° and 60° are discussed under clear, intermediate and overcast sky conditions respectively. The neural network is generated in MATLAB by using the outcomes of an optical software Photopia simulations as targets for networks training and testing. The coefficient of determination (R²) for each model is higher than 0.98, and the mean square error (MSE) is less than 0.0019, which indicate the neural network strong predictive ability and the use of the neural network method could be an efficient technique for determining the performance of lightpipe.

Keywords: neural network, bended lightpipe, transmittance, Photopia

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Authors: Benjamin Leiby, Darryl Ahner

Abstract:

This study demonstrates an alternative stochastic imputation approach for large datasets when preferred commercial packages struggle to iterate due to numerical problems. A large country conflict dataset motivates the search to impute missing values well over a common threshold of 20% missingness. The methodology capitalizes on correlation while using model residuals to provide the uncertainty in estimating unknown values. Examination of the methodology provides insight toward choosing linear or nonlinear modeling terms. Static tolerances common in most packages are replaced with tailorable tolerances that exploit residuals to fit each data element. The methodology evaluation includes observing computation time, model fit, and the comparison of known values to replaced values created through imputation. Overall, the country conflict dataset illustrates promise with modeling first-order interactions while presenting a need for further refinement that mimics predictive mean matching.

Keywords: correlation, country conflict, imputation, stochastic regression

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Authors: Nopadol Burananuth

Abstract:

The purposes of this research paper were to study the relationship between the economic factor and political factor, the relationship between political and economic factor and social factor, and the effects of economic factor, political factor, and social factor to the people’s perception about ASEAN Economic Community (AEC). A total of 400 samples were selected from four sub-districts from Arunyaprathet District, Srakaow Province. Data analysis method included multiple regression analysis. The findings revealed that political factor depended on trade cooperation, transportation cooperation, and communication cooperation. Social factor was depended on disaster protection, terrorism protection, and international relations. In addition, the people’s perception of the AEC depended on disaster perception, terrorism protection, international relations, transportation cooperation, communication cooperation, interdependence, and labor movement.

Keywords: economic factors, perception, political factors, social factors

Procedia PDF Downloads 572