Female and male student leadership characteristics: Differences & similarities

Električni bicikli postaju sve popularniji. Ekonomičan su način prijevoza koji čuva okoliš, idealni su za gradske gužve te imaju sve pogodnosti klasičnih bicikala uz minimalni tjelesni napor. Prvi patenti su zabilježeni još u 19. stoljeću, ali tek na samom kraju 20. stoljeća dobivaju na popularnosti. Prema podacima iz 2016. godine, u svijetu se svakodnevno koristi 210 milijuna električnih bicikala. Jedan od glavnih uzroka takve popularnosti je prelazak s olovnih baterija na litij-ionske. Litij-ionske baterije su lakše, brže se pune, traju dulje i imaju veću energetsku gustoću te omogućuju vozaču električnog bicikla da prijeđe veću udaljenost većom brzinom. Nedostatak litij-ionske baterije je što može biti vrlo opasna ako se ne poduzmu zaštitne mjere. Ne smije se previše isprazniti niti napuniti te se zbog toga mora nadzirati i održavati u granicama dozvoljenog napona. Potrebno je osmisliti BMS (Battery management system) te bateriju puniti pametnim punjačem koji sadrži relejni sklop za prekid punjenja baterija.Electric bicycles are becoming more popular. Being economical and environment saving type of transportation, electric bicycles are ideal for traffic congestions and offer all the benefits of traditional bicycles combined with minimal physical efforts. First patent date since 19th century, however they have started to get popular at the end of 20th century. According to data from 2016., in world there are 210 million electric bicycles being used every day. One of the main reasons for such popularity is shift from lead-acid batteries to lithium-ion ones. Lithium-ion batteries are lighter, faster to charge, have longer duration and show better energy density, which allow rider to go further and faster. Main disadvantage of lithium-ion battery is possible danger if not used correctly. It shouldn’t be discharged or charged too much thus it should be controlled and maintained within safety voltage range. It is necessary to conceive BMS (Battery management system) and charge the battery using smart charger which contains relay switch for battery charging turning off

Developing a model for mass transfer in adsorption packed-bed filters

Air filtering is an effective approach to maintain the indoor air quality while keeping the building energy consumption at an acceptable range. Adsorption filters are one of the most common types of air purifying devices. One concern about these filters, which inspired much research, is to determine their replacement time, since their efficiency decreases over time during the adsorption process. Therefore, a mass transfer model for adsorption filters had to be developed to predict the decay in filter efficiency over time as a function of the bed properties, the air flow rate, and the adsorbent-adsorbate system characteristics. This analytical model is validated systematically with experimental results obtained from a small scale and a large scale experimental setup, for two types of contaminants (MEK and n-hexane), at low, middle and high levels of inlet concentration. The model results are then compared with two previously developed models that solve the equations governing mass transfer; one is analytic and one is numerical. The proposed model shows clear advantages over those ones. Once validated, the model is applied to study the effect of varying four main operating parameters: the convective mass transfer coefficient, the diffusivity within the porous pellets, the air volume flow rate and the pellet size. When studying the effect of varying the air flow rate or the pellet size, the parametric study is carried out in large ranges of Biot number, in order to avoid the influence of convective mass transfer coefficient variations. Indeed it is shown that for large Biot number the controlling parameter is diffusivity within the particles (as anticipated) while, for small Biot number, the convective mass transfer coefficient is the dominant resistance. Finally, the variations of initial efficiency and bed saturation time with respect to changes of these four parameters are discussed

Applying GMDH-Type Neural Network and Genetic Algorithm for Stock Price Prediction of Iranian Cement Sector

The cement industry is one of the most important and profitable industries in Iran and great content of financial resources are investing in this sector yearly. In this paper a GMDH-type neural network and genetic algorithm is developed for stock price prediction of cement sector. For stocks price prediction by GMDH type-neural network, we are using earnings per share (EPS), Prediction Earnings Per Share (PEPS), Dividend per share (DPS), Price-earnings ratio (P/E), Earnings-price ratio (E/P) as input data and stock price as output data. For this work, data of ten cement companies is gathering from Tehran stock exchange (TSE) in decennial range (1999-2008). GMDH type neural network is designed by 80% of the experimental data. For testing the appropriateness of the modeling, reminder of primary data were entered into the GMDH network. The results are very encouraging and congruent with the experimental result

Micromechanical Formulation of the Yield Surface in the Plasticity of Granular Materials

An equation is proposed to unify the yield surface of granular materials by incorporating the fabric and its evolution. In microlevel analysis by employing a Fourier series that was developed to model fabric, it is directly included in the strength of granular materials. Inherent anisotropy is defined as a noncoaxiality between deposition angle and principal compressive stress. Stress-induced anisotropy is defined by the degree of anisotropy and the major direction of the contact normals. The difference between samples which have the same density (or void ratio) but different bedding angles is attributed to this equation. The validity of the formulation is verified by comparison with experimental data

Combining Fuzzy MCDM with BSC Approach in Performance Evaluation of Iranian Private Banking Sector

The objective of this study is to construct an approach based on multiple criteria decision making (MCDM) and balanced scorecard (BSC) for evaluating performance for three nongovernmental Iranian's banks. Following the literature relating to banking performance and BSC concepts, experts and managers select 21 indexes for evaluation. Furthermore, fuzzy analytic hierarchy process (FAHP) calculated the relative weights of each chosen index in order to tolerate vagueness and ambiguity of information, and three MCDM analytical tools (TOPSIS, VIKOR, and ELECTRE) were adopted to rank the banking performance. The results indicate that a customer “” has the most significant BSC perspectives and the customer satisfaction “1” is the most major index in banking sector. This proposed fuzzy MCDM method combined with BSC approach is a comprehensive and up-to-date model that can be a useful and effective assessment tool

The effects of online social networks on the quantitative academic performance of secondary high school girls' students in Tehran

Background and Objectives: One of the important indicators in measuring the quality of education is the academic performance of students, which is important from a scientific and practical point of view. Extensive studies have been conducted worldwide on how social networks affect the quantitative academic performance of their students. Many studies on the denial of social media have concluded that these networks have a negative impact on the younger generation and students. These researchers believe that virtual social networks have an effect on students' annual grade point average, drop in academic grades, writing style and spelling, decrease in English language standards, etc., and have measured these variables separately with the use of social networks among students. At the same time, others believe that the emergence of social media has a positive trend on students' performance and their achievement of high grades. These studies have also found that these students spend most of their time doing their homework and research in this way. Therefore, in the review of previous studies, both approaches are discussed separately. The main purpose of this study is to be aware of the impact of virtual social networks on the quantitative academic performance of female high school students. Sub-objectives are to examine the extent of students 'dependence on virtual social networks and awareness of the impact of using virtual social networks on students' quantitative academic performance. Methods: In this research, a survey method has been used and the sample population includes 855 female students of high schools in Tehran. The data gathering instrument is Jeffrey Single's Social Media Dependency Questionnaire, including academic quantitative performance, social networks addiction, educational use, and grammar, writing, reading, and course questions. In this study, descriptive tests (percentage, mean, and analytical tests (chi-square, Pearson correlation coefficient and t-test) were used. Findings: The findings show that there is no relationship between the students' last year GPA and their academic quantitative performance and their use of the online social network; but there is a relationship between their GPAs and their scientific information exchange (test questions) and with their use of online social networks. The findings show that there is no relationship between last year's students' grade point average and their poor academic performance using a virtual social network. There is only a relationship between their grade point average and the exchange of scientific information (exam questions) through social networks. There is also a link between social media use and poor academic performance, social media addiction, learning and receiving questions and course questions. However, the effect of social networks on the quantitative performance of students is moderate and its effect on other educational activities of students is low. Conclusion: Online social networks can be used as an appropriate way of interaction between students, as well as between teachers and students to convey scientific content, share questions and problem-solving skills, and help each other understand the correct path to problem solving. Although in this study, the use of virtual social networks does not have a negative effect on students' quantitative academic performance, but it should be noted that membership in these networks as a group and as a channel if it creates dependency and students spend a lot of time in their school hours. Can affect the quantitative academic performance of students. ===================================================================================== COPYRIGHTS  ©2020 The author(s). This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, as long as the original authors and source are cited. No permission is required from the authors or the publishers.  ====================================================================================

A method to generate computationally efficient reduced order models

A new method is presented to generate reduced order models (ROMs) in Fluid Dynamics problems. The method is based on the expansion of the flow variables on a Proper Orthogonal Decomposition (POD) basis, calculated from a limited number of snapshots, which are obtained via Computational Fluid Dynamics (CFD). Then, the POD-mode amplitudes are calculated as minimizers of a properly defined overall residual of the equations and boundary conditions. The residual can be calculated using only a limited number of points in the flow field, which can be scattered either all over the whole computational domain or over a smaller projection window. This means that the process is both computationally efficient (reconstructed flow fields require less than 1% of the time needed to compute a full CFD solution) and flexible (the projection window can avoid regions of large localized CFD errors). Also, various definitions of the residual are briefly discussed, along with the number and distribution of snapshots, the number of retained modes, and the effect of CFD errors, to conclude that the method is numerically robust. This is because the results are largely insensitive to the definition of the residual, to CFD errors, and to the CFD method itself, which may contain artificial stabilizing terms. Thus, the method is amenable for practical engineering applications

Nuclear Factor Kappa-B Protein Levels in Sperm of Obese Men with and without Diabetes; Cellular Approach in Male Infertility

Objective: Although the role of obesity and diabetes mellitus (DM) in male infertility is well established, little informationabout the underlying cellular mechanisms in infertility is available. In this sense, nuclear factor kappa-B (NF-kB) hasbeen recognized as an important regulator in obesity and DM; However, its function in the pathogenesis of maleinfertility has never been studied in obese or men who suffer from diabetes. Therefore, the main goal of current researchis assessing NF-kB existence and activity in ejaculated human spermatozoa considering the obesity and diabeticscondition of males. Materials and Methods: In an experimental study, the ELISA technique was applied to analyze NF-kB levels in spermof four experimental groups: non-obese none-diabetic men (body mass index (BMI) 30 kg/m2; OB group; n=30), non-obese diabetic men (BMI 30 kg/m2; OB-DM group; n=30) who were presented to Royan Institute Infertility Center.In addition, protein localization was shown by Immunocytofluorescent assay. Sperm features were also evaluated usingCASA. Results: The diabetic men were older than non-diabetic men regardless of obesity status (P=0.0002). Sperm progressivemotility was affected by obesity (P=0.035) and type A sperm progressive motility was affected by DM (P=0.034). Theconcentration of sperm (P=0.013), motility (P=0.025) and morphology (P<0.0001) were altered by obesity × diabetesinteraction effects. The NF-kB activity was negatively influenced by the main impact of diabetics (P=0.019). Obesitydid not affect (P=0.248) NF-kB activity. Uniquely, NF-kB localized to the midpiece of sperm and post-acrosomal areas. Conclusion: The current study indicated a lower concentration of NF-kB in diabetic men, no effect of obesity on NF-kBwas observed yet. Additionally, we revealed the main obesity and diabetes effects, and their interaction effect adverselyinfluenced sperm characteristics