Search results for: human structure interaction

Authors: R. M. López-Gutiérrez, L. Cardoza-Avendaño, H. Cervantes-de Ávila, J. A. Michel-Macarty, C. Cruz-Hernández, A. Arellano-Delgado, R. Carmona-Rodríguez

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In this paper, synchronization of multiple chaotic semiconductor lasers is achieved by appealing to complex system theory. In particular, we consider dynamical networks composed by semiconductor laser, as interconnected nodes, where the interaction in the networks are defined by coupling the first state of each node. An interesting case is synchronized with master-slave configuration in star topology. Nodes of these networks are modeled for the laser and simulated by Matlab. These results are applicable to private communication.

Keywords: chaotic laser, network, star topology, synchronization

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Authors: Shinji Ukita, Naohiro Nakamura, Yuji Miyazu

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In considering the dynamic characteristics of structure, natural frequency and damping ratio are useful indicator. When performing dynamic design, it's necessary to select an appropriate initial damping model and hysteretic model. In the linear region, the setting of initial damping model influences the response, and in the nonlinear region, the combination of initial damping model and hysteretic model influences the response. However, the dynamic characteristics of structure in the nonlinear region remain unclear. In this paper, we studied the effect of setting of initial damping model and hysteretic model on the dynamic characteristics of structure. On initial damping model setting, Initial stiffness proportional, Tangent stiffness proportional, and Rayleigh-type were used. On hysteretic model setting, TAKEDA model and Normal-trilinear model were used. As a study method, dynamic analysis was performed using a lumped mass model of base-fixed. During analysis, the maximum acceleration of input earthquake motion was gradually increased from 1 to 600 gal. The dynamic characteristics were calculated using the ARX model. Then, the characteristics of 1st and 2nd natural frequency and 1st damping ratio were evaluated. Input earthquake motion was simulated wave that the Building Center of Japan has published. On the building model, an RC building with 30×30m planes on each floor was assumed. The story height was 3m and the maximum height was 18m. Unit weight for each floor was 1.0t/m2. The building natural period was set to 0.36sec, and the initial stiffness of each floor was calculated by assuming the 1st mode to be an inverted triangle. First, we investigated the difference of the dynamic characteristics depending on the difference of initial damping model setting. With the increase in the maximum acceleration of the input earthquake motions, the 1st and 2nd natural frequency decreased, and the 1st damping ratio increased. Then, in the natural frequency, the difference due to initial damping model setting was small, but in the damping ratio, a significant difference was observed (Initial stiffness proportional≒Rayleigh type>Tangent stiffness proportional). The acceleration and the displacement of the earthquake response were largest in the tangent stiffness proportional. In the range where the acceleration response increased, the damping ratio was constant. In the range where the acceleration response was constant, the damping ratio increased. Next, we investigated the difference of the dynamic characteristics depending on the difference of hysteretic model setting. With the increase in the maximum acceleration of the input earthquake motions, the natural frequency decreased in TAKEDA model, but in Normal-trilinear model, the natural frequency didn’t change. The damping ratio in TAKEDA model was higher than that in Normal-trilinear model, although, both in TAKEDA model and Normal-trilinear model, the damping ratio increased. In conclusion, in initial damping model setting, the tangent stiffness proportional was evaluated the most. In the hysteretic model setting, TAKEDA model was more appreciated than the Normal-trilinear model in the nonlinear region. Our results would provide useful indicator on dynamic design.

Keywords: initial damping model, damping ratio, dynamic analysis, hysteretic model, natural frequency

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Authors: Yuyun, Fritz Akhmad Nuzir, Bart Julien Dewancker

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Check-in locations on social media provide information about an individual’s location. The millions of units of data generated from these sites provide knowledge for human activity. In this research, we used a geolocation service and users’ texts posted on Twitter social media to analyze human mobility. Our research will answer the questions; what are the movement patterns of a citizen? And, how far do people travel in the city? We explore the people trajectory of 201,118 check-ins and 22,318 users over a period of one month in Makassar city, Indonesia. To accommodate individual mobility, the authors only analyze the users with check-in activity greater than 30 times. We used sampling method with a systematic sampling approach to assign the research sample. The study found that the individual movement shows a high degree of regularity and intensity in certain places. The other finding found that the average distance an urban inhabitant can travel per day is as far as 9.6 km.

Keywords: mobility, check-in, distance, Twitter

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Authors: Rahul Saraswat

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More recently, a focus is given on replacing machined stainless steel metal flow-fields with inexpensive wiremesh current collectors. The flow-fields are based on simple woven wiremesh screens of various stainless steels, which are sandwiched between a thin metal plate of the same material to create a bipolar plate/flow-field configuration for use in a stack. Major advantages of using stainless steel wire screens include the elimination of expensive raw materials as well as machining and/or other special fabrication costs. Objective of the project is to improve the performance of the passive direct methanol fuel cell without increasing the cost of the cell and to make it as compact and light as possible. From the literature survey, it was found that very little is done in this direction & the following methodology was used. 1.) The passive DMFC cell can be made more compact, lighter and less costly by changing the material used in its construction. 2.) Controlling the fuel diffusion rate through the cell improves the performance of the cell. A passive liquid feed direct methanol fuel cell ( DMFC ) was fabricated using given MEA( Membrane Electrode Assembly ) and tested for different current collector structure. Mesh current collectors of different mesh densities, along with different support structures, were used, and the performance was found to be better. Methanol concentration was also varied. Optimisation of mesh size, support structure and fuel concentration was achieved. Cost analysis was also performed hereby. From the performance analysis study of DMFC, we can conclude with the following points : Area specific resistance (ASR) of wiremesh current collectors is lower than ASR of stainless steel current collectors. Also, the power produced by wiremesh current collectors is always more than that produced by stainless steel current collectors. Low or moderate methanol concentrations should be used for better and stable DMFC performance. Wiremesh is a good substitute of stainless steel for current collector plates of passive DMFC because of lower cost( by about 27 %), flexibility and light in weight characteristics of wiremesh.

Keywords: direct methanol fuel cell, membrane electrode assembly, mesh, mesh size, methanol concentration and support structure

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Authors: Mohammed Qasim, Kyoung-Dae Kim

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In this paper, we present the design of the super-ellipsoidal potential function (SEPF), that can be used for autonomous collision avoidance of an unmanned aerial vehicle (UAV) in a 3-dimensional space. In the design of SEPF, we have the full control over the shape and size of the potential function. In particular, we can adjust the length, width, height, and the amount of flattening at the tips of the potential function so that the collision avoidance motion vector generated from the potential function can be adjusted accordingly. Based on the idea of the SEPF, we also propose an approach for the local autonomy of a UAV for its collision avoidance when the UAV is teleoperated by a human operator. In our proposed approach, a teleoperated UAV can not only avoid collision autonomously with other surrounding objects but also track the operator’s control input as closely as possible. As a result, an operator can always be in control of the UAV for his/her high-level guidance and navigation task without worrying too much about the UAVs collision avoidance while it is being teleoperated. The effectiveness of the proposed approach is demonstrated through a human-in-the-loop simulation of quadrotor UAV teleoperation using virtual robot experimentation platform (v-rep) and Matlab programs.

Keywords: artificial potential function, autonomous collision avoidance, teleoperation, quadrotor

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Authors: Sonam Sandal, Susan Verghese P.

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The phrase "environmental tobacco smoke" (ETS) refers to exposure to tobacco smoke that isn't from your own smoking but instead is caused by being in close proximity to someone else's cigar, cigarette, or pipe smoke. Environmental cigarette smoke is one of the main contributors to indoor air pollution (IAP), which is exceedingly harmful to human health and results in millions of deaths each year, according to the World Health Organization. Sidestream smoke (SS), which is discharged from a cigarette's burning end in between puffs, is the primary cause of ETS. The bulk of the ETS residue is composed of gases that are produced while smoking through the cigarette paper, mainstream smoke (MS) ingested, and side stream smoke emitted while inhaling a puff from the burning end. Each of these mixtures—SS, ETS, and MS—is an aerosol composed of an IAP-causing vapor phase and a particle phase. Therefore, indoor air-cleaning equipment designed to remove particles will not significantly alter nicotine exposure but will alter the concentrations of other dangerous substances, including particulate matter (PM), PM 2.5, and PM 10. In conclusion, indoor airborne contaminants pose serious risks to human health. ETS degrades the air quality, and when someone breathes this bad air, it weakens their lungs and makes them more susceptible to COVID-19.

Keywords: pm 10, covid-19, indoor air pollution, cigarette smoke., pm 2.5

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Authors: Emma Garcia-Meca, Jennifer Martinez-Ferrero, Camino Ramon Llorens

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This paper provides insights into how narcissistic Chief Executive Officers (CEOs) influence the presence of women in top management teams (TMT). We also study whether a CEO's power and gender and the gender diversity of the firm's board moderate the relationship between CEO narcissism and TMT gender diversity. Our results reveal that narcissistic CEOs are less likely to support women in TMTs, confirming that CEO personality traits influence team structure. Further results suggest that this aversion increases as the CEO's power grows when female representation on boards decreases and when the CEO is a woman. This paper integrates theories that use the social psychology and upper echelon theories, offering a greater understanding of how CEO personality traits influence the structure of firms. We also contribute to the knowledge about how different governance characteristics can moderate the influence of narcissistic CEOs on women in TMTs, highlighting the relevance of governance traits that increase the effect of narcissism. The results demonstrate different female behavior toward promoting TMT gender equality depending on the specific position of women in the firm's hierarchy and their psychological attributes. We find that women directors support social identity values, and narcissistic female CEOs act like queen bees.

Keywords: gender diversity, board, corporate governance, female CEO, management

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Authors: Yan Zeng, Li Tao, Liujun Han, Tianye Zhang, Yongan Yu, Kaijun Ma, Long Chen

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Mechanical asphyxia is one of the main cause of death; however, death by mechanical asphyxia may be difficult to prove in court, particularly in cases in which corpses exhibit no obvious signs of asphyxia. To identify a credible biomarker of asphyxia, we first examined the expression levels of all the mRNAs in human cardiac tissue specimens subjected to mechanical asphyxia and compared these expression levels with those of the corresponding mRNAs in specimens subjected to craniocerebral injury. A total of 119 differentially expressed mRNAs were selected and the expression levels of these mRNAs were examined in 44 human cardiac tissue specimens subjected to mechanical asphyxia, craniocerebral injury, hemorrhagic shock and other causes of death. We found that DUSP1 and KCNJ2 were up-regulated in tissue specimens of mechanical asphyxia compared with control tissues, with no significant correlation between age, environmental temperature and PMI, indicating that DUSP1 and KCNJ2 may associate with mechanical asphyxia-induced death and can thus serve as useful biomarkers of death by mechanical asphyxia.

Keywords: mechanical asphyxia, biomarkers, DUSP1, KCNJ2, cardiac tissue

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Authors: Andrea Tonoli, Nicola Amati, Maria Cavatorta, Reza Mirsanei, Behzad Mozaffari, Hamed Ahani, Akbar Karamihafshejani, Mohammad Ghazivakili, Mohammad Abuabiah

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The vibrations transmitted to the drivers and passengers through vehicle seat seriously effect on the level of their attention, fatigue and physical health and reduce the comfort and efficiency of the occupants. Recently, some researchers have focused on vibrations at low excitation frequency(0.5-5 Hz) which are considered to be the main risk factors for lumbar part of the backbone but they were not applicable to A and B-segment cars regarding to the size and weight. A semi-active system with two symmetric negative stiffness structures (NSS) in parallel to a positive stiffness structure and actuators has been proposed to attenuate low frequency excitation and makes system flexible regarding to different weight of passengers which is applicable for A and B-Segment cars. Here, the 3 degree of freedom system is considered, dynamic equation clearly is presented, then simulated in MATLAB in order to analysis of performance of the system. The design procedure is derived so that the resonance peak of frequency–response curve shift to the left, the isolating range is increased and especially, the peak of the frequency–response curve is minimized. According to ISO standard different class of road profile as an input is applied to the system to evaluate the performance of the system. To evaluate comfort issues, we extract the RMS value of the vertical acceleration acting on the passenger's body. Then apply the band-pass filter, which takes into account the human sensitivity to acceleration. According to ISO, this weighted acceleration is lower than 0.315 m/s^2, so the ride is considered as comfortable.

Keywords: low frequency excitation, negative stiffness, seat vehicle, vibration isolation

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Authors: K. S. Poutanen, P. Dussort, A. Erkner, S. Fiszman, K. Karnik, M. Kristensen, C. F. M. Marsaux, S. Miquel-Kergoat, S. Pentikäinen, P. Putz, R. E. Steinert, J. Slavin, D. J. Mela

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Dietary fiber (DF) intake has been associated with lower body weight or less weight gain. These effects are generally attributed to putative effects of DF on appetite. Many intervention studies have tested the effect of DFs on appetite-related measures, with inconsistent results. However, DF includes a wide category of different compounds with diverse chemical and physical characteristics, and correspondingly diverse effects in human digestion. Thus, inconsistent results between DF consumption and appetite are not surprising. The specific contribution of different compounds with varying physico-chemical properties to appetite control and the mediating mechanisms are not well characterized. This systematic review aimed to assess the influence of specific DF characteristics, including viscosity, gel forming capacity, fermentability, and molecular weight, on appetite-related outcomes in healthy humans. Medline and FSTA databases were searched for controlled human intervention trials, testing the effects of well-characterized DFs on subjective satiety/appetite or energy intake outcomes. Studies were included only if they reported: 1) fiber name and origin, and 2) data on viscosity, gelling properties, fermentability, or molecular weight of the DF materials tested. The search generated 3001 unique records, 322 of which were selected for further consideration from title and abstract screening. Of these, 149 were excluded due to insufficient fiber characterization and 124 for other reasons (not original article, not randomized controlled trial, or no appetite related outcome), leaving 49 papers meeting all the inclusion criteria, most of which reported results from acute testing (<1 day). The eligible 49 papers described 90 comparisons of DFs in foods, beverages or supplements. DF-containing material of interest was efficacious for at least one appetite-related outcome in 51/90 comparisons. Gel-forming DF sources were most consistently efficacious but there were no clear associations between viscosity, MW or fermentability and appetite-related outcomes. A considerable number of papers had to be excluded from the review due to shortcomings in fiber characterization. To build understanding about the impact of DF on satiety/appetite specifically there should be clear hypotheses about the mechanisms behind the proposed beneficial effect of DF material on appetite, and sufficient data about the DF properties relevant for the hypothesized mechanisms to justify clinical testing. The hypothesized mechanisms should also guide the decision about relevant duration of exposure in studies, i.e. are the effects expected to occur during acute time frame (related to stomach emptying, digestion rate, etc.) or develop from sustained exposure (gut fermentation mediated mechanisms). More consistent measurement methods and reporting of fiber specifications and characterization are needed to establish reliable structure-function relationships for DF and health outcomes.

Keywords: appetite, dietary fiber, physico-chemical properties, satiety

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Authors: Seung Chul Lee, Jooyeong Kim, Ki Ok Ahn, Juok Park

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Background: Injuries caused by motorcycle crashes are one of the major public health burdens leading to high mortality, functional disability. The risk of death among motorcyclists is 30 times greater than that among car drivers, with head injuries the leading cause of death. The motorcycle helmet is crucial protective equipment for motorcyclists. Aims: This study aimed to measure the protective effect of motorcycle helmet use on intracranial injury and mortality and to compare the preventive effect in drivers and passengers. Methods: This is a cross-sessional study based on the Emergency Department (ED)–based Injury In-depth Surveillance (EDIIS) database from 23 EDs in Korea. All of the trauma patients injured in motorcycle crashes between January 1, 2013 and December 31, 2016 were eligible, excluding cases with unknown helmet use and outcomes. The primary and secondary outcomes were intracranial injury and in-hospital mortality. We calculated adjusted odds ratios (AORs) of helmet use for study outcomes after adjusting for potential confounders. Using interaction models, we compared the protective effect of helmet use on outcomes across driving status (driver and passenger). Results: Among 17,791 eligible patients, 10,668 (60.0%) patients were wearing helmets at the time of the crash, 2,128 (12.0%) patients had intracranial injuries and 331 (1.9%) patients had in-hospital death. 16,381 (92.1%) patients were drivers and 1410 (7.9%) patients were passengers. 62.6% of drivers and 29.1% of passengers were wearing helmets at the time of the crash. Compared to un-helmeted group, the helmeted group was less likely to have an intracranial injury(8.0% vs. 17.9%, AOR: 0.43 (0.39-0.48)) and in-hospital mortality (1.0% vs. 3.2%, AOR: 0.29 (0.22-0.37)).In the interaction model, AORs (95% CIs) of helmet use for intracranial injury were 0.42 (0.38-0.47) in drivers and 0.61(0.41-0.90) in passengers, respectively. There was a significant preventive effect of helmet use on in-hospital mortality in drivers (AOR: 0.26(0.21–0.34)). Discussion and conclusions: Wearing helmets in motorcycle crashes reduced intracranial injuries and in-hospital mortality. The preventive effect of motorcycle helmet use on intracranial injury was stronger in drivers than in passengers. There was a significant preventive effect of helmet use on in-hospital mortality in driver but not in passengers. Public health efforts to increase motorcycle helmet use are needed to reduce health burden from injuries caused by motorcycle crashes.

Keywords: intracranial injury, helmet, mortality, motorcycle crashes

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Authors: Hongtao Zhu, Dezhi Sun

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Nitrogen and phosphorus are essential nutrients for biomass growth. But excessive nitrogen and phosphorus can contribute to accelerated eutrophication of lakes and rivers. Constructed wetland is an efficient and eco-friendly wastewater treatment technology with low operating cost and low-energy consumption. Because of high affinity with ammonium ion, zeolite, as a common substrate, is applied in constructed wetlands worldwide. Another substrate seen commonly for constructed wetlands is steel slag, which has high contents of Ca, Al, or Fe, and possesses a strong affinity with phosphate. Due to the excellent ammonium removal ability of zeolite and phosphate removal ability of steel slag, they were considered to be combined in the substrate bed of a constructed wetland in order to enhance the simultaneous removal efficiencies of nitrogen and phosphorus. In our early tests, zeolite and steel slag were combined with each other in order to simultaneously achieve a high removal efficiency of ammonium-nitrogen and phosphate-phosphorus. However, compared with the results when only zeolite was used, the removal efficiency of ammonia was sharply decreased when zeolite and steel slag were used together. The main objective of this study was to establish an overview of the interaction of steel slag and zeolite on ammonium nitrogen removal. The CaO dissolution from slag, as well as the effects of influencing parameters (i.e. pH and Ca2+ concentration) on the ammonium adsorption onto zeolite, was systematically studied. Modeling results of Ca2+ and OH- release from slag indicated that pseudo-second order reaction had a better fitness than pseudo-first order reaction. Changing pH value from 7 to 12 would result in a drastic reduction of the ammonium adsorption capacity on zeolite, from the peak at pH7. High Ca2+ concentration in solution could also inhibit the adsorption of ammonium onto zeolite. The mechanism for steel slag inhibiting the ammonium adsorption capacity of zeolite includes: on one hand, OH- released from steel slag can react with ammonium ions to produce molecular form ammonia (NH3∙H2O), which would cause the dissociation of NH4+ from zeolite. On the other hand, Ca2+ could replace the NH4+ ions to adhere onto the surface of zeolite. An innovative substrate filling configuration that zeolite and steel slag are placed sequentially was proposed to eliminate the disadvantageous effects of steel slag. Experimental results showed that the novel filling configuration was superior to the other two contrast filling configurations in terms of ammonium removal.

Keywords: ammonium nitrogen, constructed wetlands, steel slag, zeolite

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Authors: Siyuan Cai

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This paper takes community segregation during major infectious diseases as the background, based on the physiological needs and safety needs of citizens during home segregation, and based on the selection of convenient facilities and medical facilities as the main research objects. Based on the POI data of public facilities in Chongqing, the spatial distribution characteristics of the convenience and medical facilities in the 15-minute living circle centered on three neighborhoods in Shapingba, namely Shengwei Community, Anju Commmunity and Fengtian Garden Community, were explored by means of GIS spatial analysis. The results show that the spatial distribution of convenience and medical facilities in this area has significant clustering characteristics, with a point-like distribution pattern of "dense in the west and sparse in the east", and a grouped and multi-polar spatial structure. The spatial structure is multi-polar and has an obvious tendency to the intersections and residential areas with dense pedestrian flow. This study provides a preliminary exploration of the distribution of medical and convenience facilities within the 15-minute living circle of a segregated community, which makes up for the lack of spatial research in this area.

Keywords: ArcGIS, community segregation, convenient facilities; distribution pattern, medical facilities, POI, 15-minute community life circle

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Authors: Reihaneh Ahmadzadeh Ghavidel

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Free radicals such as reactive oxygen species (ROS) have detrimental effects on human health through several mechanisms. On the other hand, antioxidant molecules reduce free radical generation in biologic systems. Synthetic antioxidants, which are used in food industry, have also negative impact on human health. Therefore recognition of natural antioxidants such as anthocyanins can solve these problems simultaneously. Coleus (Solenostemon scutellarioides) with red leaves is a rich source of anthocyanins compounds. In this study we evaluated the effect of time (10, 20 and 30 min) and temperature (40, 50 and 60° C) on optimization of anthocyanin extraction using surface response method. In addition, the study was aimed to determine maximum extraction for anthocyanin from coleus plant using ultrasound method. The results indicated that the optimum conditions for extraction were 39.84 min at 69.25° C. At this point, total compounds were achieved 3.7451 mg 100 ml⁻¹. Furthermore, under optimum conditions, anthocyanin concentration, extraction efficiency, ferric reducing ability, total phenolic compounds and EC50 were registered 3.221931, 6.692765, 223.062, 3355.605 and 2.614045, respectively.

Keywords: anthocyanin, antioxidant, coleus, extraction, sonication

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Authors: Paria Tajabor, Azin Azarbani

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The purpose of this research study is exploring two kind of semantic repositories with regards to various factors to find the best approaches that an artificial manager can use to produce ontology in a system based on their interaction, association and research. To this end, as the best way to evaluate each system and comparing with others is analysis, several benchmarking over these two repositories were examined. These two semantic repositories: OWLIM and AllegroGraph will be the main core of this study. The general objective of this study is to be able to create an efficient and cost-effective manner reports which is required to support decision making in any large enterprise.

Keywords: OWLIM, allegrograph, RDF, reasoning, semantic repository, semantic-web, SPARQL, ontology, query

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Authors: Manjit Singha, Sandeep Singh Sandhu, A. S. Shahi

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Stellite 6 is cobalt based superalloy used for protective coatings. It is used to improve the wear performance of stainless steel engineering components subjected to harsh environmental conditions. This paper reports the high temperature wear analysis of satellite 6 cladded on AISI 304 L substrate using SMAW process. Bead on plate experiment was carried out by varying current and electrode manipulation techniques to optimize the dilution and hardness. 80 Amp current and weaving technique was found to be the optimum set of parameters for overlaying which were further used for multipass multilayer cladding on two plates of AISI 304 L substrate. On the first plate, seven layers seven passes of stellite 6 was overlaid which was used in as cladded form and the second plate was overlaid with five layers five passes of satellite 6 with further TIG remelting. The wear performance was examined for normal temperature environmental condition and harsh temperature environmental condition. The satellite 6 coating with TIG remelting was found to be better in both the conditions even with lesser metal deposition due to its finer grain structure.

Keywords: surfacing, stellite 6, dilution, overlay, SMAW, high-temperature frictional wear, micro-structure, micro-hardness

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Authors: I Putu Indra Kusuma

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The rapid development of Information and Communication Technology (ICT) tools has improved the implementation of flipped classrooms in English Language Teaching (ELT), especially in speaking course. Flipped classrooms have therefore evolved from the oldest version, which uses recorded videos to the newest one (3.0 version), which combines various materials and enables out-of-class interaction and learning engagement. However, how the latest version of flipped classrooms affects students’ speaking performance and influences students’ learning engagement remains unclear. This study therefore sought (1) to examine the effect of flipped classrooms 3.0 towards students’ speaking performance and (2) to explore the students’ learning engagement during the implementation of flipped classrooms in the speaking course. This study then employed explanatory sequential mixed-method design. This study conducted a quasi-experimental study by recruiting 164 twelfth grade students of a public senior high school in Indonesia as the sample. They were distributed into experimental (80 students) and control (84 students) groups. The experimental group was treated by implementing flipped classrooms with various use of ICT tools such as Schoology, Youtube, websites, and Flipgrid for eight weeks. Meanwhile, the control group implemented a conventional method. Furthermore, there were two variables examined in this study, such as the implementation of flipped classrooms 3.0 as the independent variable and students’ speaking performance as the dependent variable. The data of these two variables were then collected through administering a speaking test to both groups. The data from this experimental study were analyzed by using independent t-test analysis. Also, five students were invited to participate in semi-structured interviews to explore their learning engagement during the implementation of flipped classrooms. The findings revealed that there was a significant difference in students’ speaking performance between experimental where t (df = 162) = 5.810, p < 0.001, d = 0.91 in which experimental group performed better in speaking than the control group. Also, the results of interviews showed that the students had positive learning engagement during the implementation of flipped classrooms 3.0, especially on out-of-class interactions and face-to-face meetings. Some relevant implications to ELT, especially in speaking courses, are also drawn from the data findings. From the findings, it can be concluded that flipped classrooms 3.0 has a significant effect on students’ speaking performance and it promotes students’ learning engagement. Therefore, flipped classrooms 3.0 should be embraced as the newest version of flipped classrooms that promotes interaction outside the classrooms and learning engagement.

Keywords: Flipped Classrooms 3.0, learning engagement, teaching speaking with technology, technology-enhanced language learning

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Authors: Alya Harichane, Abderraouf Achour, Abdelbaki Benmounah

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The main difficulty encountered in the formulation of high-performance concrete (HPC) consists in choosing the most efficient cement-superplasticizer pair allowing to obtain maximum water reduction, good workability of the concrete in the fresh state, and very good mechanical resistance in the hardened state. The aim of this work is to test the efficiency of three polycarboxylate ether-based superplasticizers (PCE) marketed in Algeria with CEMI 52.5 R cement and to study the effect of chemical structure of PCE on zeta potential, rheological and mechanical properties of cement pastes. The property of the polymers in cement was tested by a Malvern Zetasizer 2000 apparatus and VT 550 viscometer. Results showed that the zeta potential and its rheological properties are related to the molecular weight and the density carboxylic of PCE. The PCE with a moderate molecular weight and the highest carboxylic groups had the best dispersion (high value of zeta potential) and lowest viscosity. The effect of the chemical structure of PCEs on mechanical properties is evaluated by the formulation of cement mortar with these PCEs. The result shows that there is a correlation between the zeta potential of polymer and the compressive strength of cement paste.

Keywords: molecular weight, polycarboxylate-ether superplasticizer, rheology, zeta potential

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Authors: Julia Reinold, Inge Hooijen, Christoph Meng, Melissa Siegel

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This paper investigates whether or not students intend to stay in the Euregio Meuse-Rhine (EMR) after graduation taking into account the role of hard and soft locational factors, social factors as well as demographic aspects in shaping their mobility preferences. Since graduates are considered a convenient source of human capital in today’s knowledge based economy, it is crucial to understand what drives their mobility intentions in order to retain larger numbers of graduates. This is particularly true for peripheral regions, which need to compete with assumed more attractive economic centres. This paper adds a euregional perspective to the existing literature on graduate migration. Using survey data from 2015 from five higher education institutions in the EMR, this paper finds that mobility intentions are determined by students’ perceptions of the quality of life, openness and career opportunities in the euroregion. In addition, distance to the partner and other social ties such as family and friends influence migration intentions.

Keywords: Euroregion, graduate migration, highly skilled migration, human capital

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Authors: Roxana Maria Angelescu, Doina Răducanu, Mariana Lucia Angelescu, Ion Cincă, Vasile Dănuţ Cojocaru, Cosmin Cotruț, Şerban Nicolae

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Titanium alloys are often used for biomedical applications as hard tissue replacements, such as: orthopedic implants, spinal fixation devices and dental implants. Their advantages are well known and demonstrated: excellent mechanical properties, biocompatibility and good corrosion resistance, but it is also known that the main disadvantage of the metallic materials is their tendency of corrosion in in-vivo environments. In 1987, titanium was found to be the only metallic biomaterial that osseointegrates. The aim of this study was to investigate the microstructure and the corrosion behavior of the Ti-20Nb-5Ta wt% alloy. In this case Nb stabilizes the β-Ti structure and Ta is a highly passivating metal. The as studied alloy was melt under argon protective atmosphere in a levitation induction melting furnace, type FIVE CELES - MP25, with a nominal power of 25 kW and a melting capacity of 30 cm3. The microstructure of the as studied alloy was analyzed by using the electronic microscope Tescan Vega II-XMU. The phase structure of the as studied alloy was determined, as well as the crystalline grain size (100-200µ). To determine the corrosion behavior of the as studied alloy, the technique used was the linear polarization, with the PARSTAT 4000 potentiostat, produced by Princeton Applied Research; potentiodynamic curves were obtained with the VeraStudio v.2.4.2 software.

Keywords: corrosion resistance, microstructure, titanium alloys

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Authors: Reem Alkadeem

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This study aims at evaluating the overall satisfaction of faculty members and relating it to organizational and personal aspects in Egyptian public and private universities. These aspects are identified through an extensive study of all factors that might affect job satisfaction. The most influencing parameters selected are academics’ demographics, human resource management, organizational profile, workload, teamwork skills, recognition, autonomy, teaching activity, research activity, and motivation. A questionnaire of 94 questions was used to assess job satisfaction and the previously mentioned parameters. It was distributed among seven hundred members of different universities in Egypt. Two hundred and twenty-seven faculty members responded. This sample was gathered from twelve universities and The Supreme Council of Universities. The ANOVA showed a significant relationship (p < 0.05) between eight of the selected parameters and job satisfaction. These parameters are age, rank, human resource management, profile of organizational characteristics, workload, recognition, teaching activity, and motivation.

Keywords: job satisfaction, higher education, organizational profile, Egyptian universities

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Authors: K. Jankowski, M. Pawlikowski, A. Makuch, K. Skalski

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Depth-sensing indentation (DSI) or nanoindentation is becoming a more and more popular method of measuring mechanical properties of various materials and tissues at a micro-scale. This technique allows measurements without complicated sample preparation procedures which makes this method very useful. As a result of measurement force and displacement of the intender are obtained. It is also possible to determine three measures of hardness i.e. Martens hardness (HM), nanohardness (HIT), Vickers hardness (HV) and Young modulus EIT. In this work trabecular bone mechanical properties were investigated. The bone samples were harvested from human femoral heads during hip replacement surgery. Patients were of different age, sexes and stages of tissue degeneration caused by osteoarthritis. The specimens were divided into three groups. Each group contained samples harvested from patients of different range of age. All samples were investigated with the same measurement conditions. The maximum load was Pmax=500 mN and the loading rate was 500 mN/min. The tests were held without hold at the peak force. The tests were conducted with indenter Vickers tip and spherical tip of the diameter 0.2 mm. Each trabecular bone sample was tested 7 times in a close area of the same trabecula. The measured loading P as a function of indentation depth allowed to obtain hysteresis loop and HM, HIT, HV, EIT. Results for arbitrarily chosen sample are HM=289.95 ± 42.31 MPa, HIT=430.75 ± 45.37 MPa, HV=40.66 ± 4.28 Vickers, EIT=7.37 ± 1.84 GPa for Vickers tip and HM=115.19 ± 15.03 MPa, HIT=165.80 ± 19.30 MPa, HV=16.90 ± 1.97 Vickers, EIT=5.30 ± 1.31 GPa for spherical tip. Results of nanoindentation tests show that this method is very useful and is perfect for obtaining mechanical properties of trabecular bone. Estimated values of elastic modulus are similar. The differences between hardness are significant but it is a result of using two different types of tips. However, it has to be emphasised that the differences in the values of elastic modulus and hardness result from different testing protocols, anisotropy and asymmetry of the micro-samples and the hydration of bone.

Keywords: human bone, mechanical properties, nano hardness nanoindentation, trabecular bone

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Authors: Hyeon-Kyo Lim, Hyunjung Kim, Kune-Woo Lee

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Decommissioning process of nuclear facilities can be said to consist of a sequence of problem solving activities, partly because there may exist working environments contaminated by radiological exposure, and partly because there may also exist industrial hazards such as fire, explosions, toxic materials, and electrical and physical hazards. As for an individual hazard factor, risk assessment techniques are getting known to industrial workers with advance of safety technology, but the way how to integrate those results is not. Furthermore, there are few workers who experienced decommissioning operations a lot in the past. Therefore, not a few countries in the world have been trying to develop appropriate counter techniques in order to guarantee safety and efficiency of the process. In spite of that, there still exists neither domestic nor international standard since nuclear facilities are too diverse and unique. In the consequence, it is quite inevitable to imagine and assess the whole risk in the situation anticipated one by one. This paper aimed to find out an appropriate technique to integrate individual risk assessment results from the viewpoint of experts. Thus, on one hand the whole risk assessment activity for decommissioning operations was modeled as a sequence of individual risk assessment steps, and on the other, a hierarchical risk structure was developed. Then, risk assessment procedure that can elicit individual hazard factors one by one were introduced with reference to the standard operation procedure (SOP) and hierarchical task analysis (HTA). With an assumption of quantification and normalization of individual risks, a technique to estimate relative weight factors was tried by using the conventional Analytic Hierarchical Process (AHP) and its result was reviewed with reference to judgment of experts. Besides, taking the ambiguity of human judgment into consideration, debates based upon fuzzy inference was added with a mathematical case study.

Keywords: decommissioning, risk assessment, analytic hierarchical process (AHP), fuzzy inference

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Authors: Valeriy M. Kondratev, Ekaterina A. Vyacheslavova, Talgat Shugabaev, Alexander S. Gudovskikh, Alexey D. Bolshakov

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Modern sensorics imposes strict requirements on the biosensors characteristics, especially technological feasibility, and selectivity. There is a growing interest in the analysis of human health biological markers, which indirectly testifying the pathological processes in the body. Such markers are acids and alkalis produced by the human, in particular - ammonia and hydrochloric acid, which are found in human sweat, blood, and urine, as well as in gastric juice. Biosensors based on modern nanomaterials, especially low dimensional, can be used for this markers detection. Most classical adsorption sensors based on metal and silicon oxides are considered non-selective, because they identically change their electrical resistance (or impedance) under the action of adsorption of different target analytes. This work demonstrates a feasible frequency-resistive method of electrical impedance spectroscopy data analysis. The approach allows to obtain of selectivity in adsorption sensors of a resistive type. The method potential is demonstrated with analyzis of impedance spectra of silicon nanowires in the presence of NH3 and HCl vapors with concentrations of about 125 mmol/L (2 ppm) and water vapor. We demonstrate the possibility of unambiguous distinction of the sensory signal from NH3 and HCl adsorption. Moreover, the method is found applicable for analysis of the composition of ammonia and hydrochloric acid vapors mixture without water cross-sensitivity. Presented silicon sensor can be used to find diseases of the gastrointestinal tract by the qualitative and quantitative detection of ammonia and hydrochloric acid content in biological samples. The method of data analysis can be directly translated to other nanomaterials to analyze their applicability in the field of biosensory.

Keywords: electrical impedance spectroscopy, spectroscopy data analysis, selective adsorption sensor, nanotechnology

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Authors: S. Srinivas, N. Ramesh Babu

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This paper presents a model to predict the depth of penetration in polycrystalline ceramic material cut by abrasive waterjet. The proposed model considered the interaction of cylindrical jet with target material in upper region and neglected the role of threshold velocity in lower region. The results predicted with the proposed model are validated with the experimental results obtained with Silicon Carbide (SiC) blocks.

Keywords: abrasive waterjet cutting, analytical modeling, ceramics, micro-cutting and inter-grannular cracking

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Authors: Maciej Życki, Anna Kowalik-klimczak, Monika Łożyńska, Wioletta Barszcz, Jolanta Drabik Anna Kowalik-klimczak

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The rapidly changing fashion trends generate huge amounts of leather and textile waste globally. The complexity of these types of waste makes recycling difficult in economic terms. Pyrolysis is suggested for this purpose, which transforms heterogeneous and complex waste into added-value products e.g. active carbons and soil fertilizer. The possibility of using pyrolysis for the valorization of leather and textile waste has been analyzed in this paper. In the first stage, leather and textile waste were subjected to TG/DTG thermogravimetric and DSC calorimetric analysis. These analyses provided basic information about thermochemical transformations and degradation rates during the pyrolysis of these types of waste and enabled the selection of the pyrolysis temperature. In the next stage, the effect of gas type using pyrolysis was investigated on the physicochemical properties, composition, structure, and formation of the specific surfaces of carbonized materials produced by means of a thermal treatment without oxygen access to the reaction chamber. These studies contribute some data about the thermal management and pyrolytic processing of leather and textile waste into useful carbonized materials, according to the circular economy model.

Keywords: pyrolysis, leather and textiles waste, composition and structure of carbonized materials, valorisation of waste, circular economy model

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Authors: Junze Li, M. Li

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Laser diodes fabricated from the III-nitride material system are emerging solutions for the next generation telecommunication systems and optical clocks based on Ca at 397nm, Rb at 420.2nm and Yb at 398.9nm combined 556 nm. Most of the applications require single longitudinal optical mode lasers, with very narrow linewidth and compact size, such as communication systems and laser cooling. In this case, the GaN based distributed feedback (DFB) laser diode is one of the most effective candidates with gratings are known to operate with narrow spectra as well as high power and efficiency. Given the wavelength range, the period of the first-order diffraction grating is under 100 nm, and the realization of such gratings is technically difficult due to the narrow line width and the high quality nitride overgrowth based on the Bragg grating. Some groups have reported GaN DFB lasers with high order distributed feedback surface gratings, which avoids the overgrowth. However, generally the strength of coupling is lower than that with Bragg grating embedded into the waveguide within the GaN laser structure by two-step-epitaxy. Therefore, the overgrowth on the grating technology need to be studied and optimized. Here we propose to fabricate the fine step shape structure of first-order grating by the nanoimprint combined inductively coupled plasma (ICP) dry etching, then carry out overgrowth high quality AlGaN film by metalorganic chemical vapor deposition (MOCVD). Then a series of gratings with different period, depths and duty ratios are designed and fabricated to study the influence of grating structure to the nano-heteroepitaxy. Moreover, we observe the nucleation and growth process by step-by-step growth to study the growth mode for nitride overgrowth on grating, under the condition that the grating period is larger than the mental migration length on the surface. The AFM images demonstrate that a smooth surface of AlGaN film is achieved with an average roughness of 0.20 nm over 3 × 3 μm2. The full width at half maximums (FWHMs) of the (002) reflections in the XRD rocking curves are 278 arcsec for the AlGaN film, and the component of the Al within the film is 8% according to the XRD mapping measurement, which is in accordance with design values. By observing the samples with growth time changing from 200s, 400s to 600s, the growth model is summarized as the follow steps: initially, the nucleation is evenly distributed on the grating structure, as the migration length of Al atoms is low; then, AlGaN growth alone with the grating top surface; finally, the AlGaN film formed by lateral growth. This work contributed to carrying out GaN DFB laser by fabricating grating and overgrowth on the nano-grating patterned substrate by wafer scale, moreover, growth dynamics had been analyzed as well.

Keywords: DFB laser, MOCVD, nanoepitaxy, III-niitride

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Authors: Clea Southall

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Many children leave primary school having formed preconceptions about their relationship with science. Thus, primary school represents a critical window for stimulating scientific interest in younger children. Engagement relies on the provision of hands-on activities coupled with an ability to capture a child’s innate curiosity. This requires children to perceive science topics as interesting and relevant to their everyday life. Teachers and pupils alike have suggested the school curriculum be tailored to help stimulate scientific interest. Young children are naturally inquisitive about the human body; the brain is one topic which frequently engages pupils, although it is not currently included in the UK primary curriculum. Teaching children about the brain could have wider societal impacts such as increasing knowledge of neurological disorders. However, many primary school teachers do not receive formal neuroscience training and may feel apprehensive about delivering lessons on the nervous system. This is exacerbated by a lack of educational neuroscience resources. One solution is for undergraduates to form partnerships with schools - delivering engaging lessons and supplementing teacher knowledge. The aim of this project was to evaluate the success of a short lesson on the brain delivered by an undergraduate neuroscientist to primary school pupils. Prior to entering schools, semi-structured online interviews were conducted with teachers to gain pedagogical advice and relevant websites were searched for neuroscience resources. Subsequently, a single lesson plan was created comprising of four hands-on activities. The activities were devised in a top-down manner, beginning with learning about the brain as an entity, before focusing on individual neurons. Students were asked to label a ‘brain map’ to assess prior knowledge of brain structure and function. They viewed animal brains and created ‘pipe-cleaner neurons’ which were later used to depict electrical transmission. The same session was delivered by an undergraduate student to 570 key stage 2 (KS2) pupils across five schools in Leeds, UK. Post-session surveys, designed for teachers and pupils respectively, were used to evaluate the session. Children in all year groups had relatively poor knowledge of brain structure and function at the beginning of the session. When asked to label four brain regions with their respective functions, older pupils labeled a mean of 1.5 (± 1.0) brain regions compared to 0.8 (± 0.96) for younger pupils (p=0.002). However, by the end of the session, 95% of pupils felt their knowledge of the brain had increased. Hands-on activities were rated most popular by pupils and were considered the most successful aspect of the session by teachers. Although only half the teachers were aware of neuroscience educational resources, nearly all (95%) felt they would have more confidence in teaching a similar session in the future. All teachers felt the session was engaging and that the content could be linked to the current curriculum. Thus, a short fifty-minute session can successfully enhance pupils’ knowledge of a new topic: the brain. Partnerships with an undergraduate student can provide an alternative method for supplementing teacher knowledge, increasing their confidence in delivering future lessons on the nervous system.

Keywords: education, neuroscience, primary school, undergraduate

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Authors: Mahmoud H. Abu Elella, Riham R. Mohamed, Magdy W. Sabaa

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Introduction: Microbial pollution is global problem threatening the human health. It is resulted by pathogenic microorganisms such as Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and other pathogenic strains. They cause a dangerous effect on human health, so great efforts have been exerted to produce new and effective antimicrobial agents. Nowadays, natural polysaccharides, such as chitosan and its derivatives are used as antimicrobial agents. The aim of our work is to synthesize of a biodegradable polymer such as N-quaternized chitosan (NQC) then Characterization of NQC by using different analysis techniques such as Fourier transform infrared (FTIR) and Scanning electron microscopy (SEM) and using it as an antibacterial agent against different pathogenic bacteria. Methods: Synthesis of NQC using dimethylsulphate. Results: FTIR technique exhibited absorption peaks of NQC, SEM images illustrated that surface of NQC was smooth and antibacterial results showed that NQC had a high antibacterial effect. Discussion: NQC was prepared and it was proved by FTIR technique and SEM images antibacterial results exhibited that NQC was an antibacterial agent.

Keywords: antimicrobial agent, N-quaternized chitosan chloride, silver nanocomposites, sodium polyacrylate

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Authors: Mohammed Messaoudi

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The higher education sector in Algeria has witnessed in recent years a remarkable transformation, as it witnessed the integration of institutions within the modern technological environment and harnessing all appropriate mechanisms to raise the level of education and the level of training. Observers and those interested that it is necessary for the Algerian university to enter this field, especially with the efforts that seek to employ modern technology in the sector and encourage investment in this field, in addition to the state’s keenness to move towards building a path to benefit from modern technology, and to encourage energies in light of a reality that carries many Aspirations and challenges by achieving openness to the new digital environment and keeping pace with the ranks of international universities. Higher education is one of the engines of development for societies, as it is a vital field for the transfer of knowledge and scientific expertise, and the university is at the top of the comprehensive educational system for various disciplines in light of the achievement of a multi-dimensional educational system, and amid the integration of three basic axes that establish the sound educational process (teaching, research, relevant outputs efficiency), and according to a clear strategy that monitors the advancement of academic work, and works on developing its future directions to achieve development in this field. The Algerian University is considered one of the service institutions that seeks to find the optimal mechanisms to keep pace with the changes of the times, as it has become necessary for the university to enter the technological space and thus ensure the quality of education in it and achieve the required empowerment by dedicating a structure that matches the requirements of the challenges on which the sector is based, amid unremitting efforts to develop the capabilities. He sought to harness the mechanisms of communication and information technology and achieve transformation at the level of the higher education sector with what is called higher education technology. The conceptual framework of information and communication technology at the level of higher education institutions in Algeria is determined through the factors of organization, factors of higher education institutions, characteristics of the professor, characteristics of students, the outcomes of the educational process, and there is a relentless pursuit to achieve a positive interaction between these axes as they are basic components on which the success and achievement of higher education are based for his goals.

Keywords: Information and communication technology, Algerian university, scientific and cognitive development, challenges

Procedia PDF Downloads 85