33 research outputs found
Cobertura Fornecendo em Redes de Sensores Direcionais através de Algoritmos de Aprendizagem (Autômatos de Aprendizagem)
Today, wireless sensor networks due to application development are widely used. There are significant issues in these networks; they can be more effective if they would be fixed. One of these problems is the low coverage of these networks due to their low power. If coverage increases only by increasing the power of sending and receiving power, it can increase network consumption as a catastrophic disaster, while the lack of energy is one of the most important constraints on these networks. To do this, the antenna coverage is oriented in some sensor networks to cover the most important places. This method tries to improves the efficiency and coverage of directional sensor networks by providing a mechanism based on the learning algorithm of the machine called learning automata. Results show this method outperform the before methods at least 20%.Hoy en dĂa, las redes de sensores inalámbricos debido al desarrollo de aplicaciones son ampliamente utilizadas. Hay problemas importantes en estas redes; pueden ser más efectivos si se solucionan. Uno de estos problemas es la baja cobertura de estas redes debido a su baja potencia. Si la cobertura aumenta solo elevando la potencia de envĂo y recepciĂłn de energĂa, puede aumentar el consumo de red como un desastre catastrĂłfico, mientras que la falta de energĂa es una de las limitaciones más importantes de estas redes. Para hacer esto, la cobertura de la antena está orientada en algunas redes de sensores para cubrir los lugares más importantes. Este mĂ©todo intenta mejorar la eficiencia y la cobertura de las redes de sensores direccionales al proporcionar un mecanismo basado en el algoritmo de aprendizaje de la máquina denominado autĂłmatas de aprendizaje. Los resultados muestran que este mĂ©todo supera los mĂ©todos anteriores al menos un 20%.Hoy en dĂa, as redes de sensores inalámbricos debitaram o desenvolvimento de aplicações sonoras extensamente utilizadas. Obras do feno importantes nas redes; pueden ser más effectivos e se solucionan. Uns de esos protes es la baja cobertura de es redes debido a su baja potencia. Se a porta leva sozinho a aumentar a potĂŞncia de envio e a recepção de energia, aumentar o consumo de energia como um desastre catastrĂłfico, a falta de energia de energia Ă© uma das limitações mais importantes destas redes. Para hacer esto, a cobertura da antena está orientada nas algunas redes de sensores para cubrir os lugares mais importantes. This method intenta mejor a eficiencia and the coverage of the networks of sensors directionals are provided in engine based on the algorithm of aprendizado of the machine denominado autĂłmatas de aprendizaje. Los resultados muestran que este mĂ©todo supera os mĂ©todos anteriores a menos de 20%
ESP Courses and Identity Formation: The Case of Introvert Students
Identity formation is one of the main concerns of today’s education and can have a vital role in ESP learners’ future professional success. This study investigated whether the employment of interactive practices in ESP courses had any impact on the identity formation of introvert students. Initially, 200 undergraduate students majoring in Computer Sciences, Accounting, and Physical Education answered the introversion/extraversion section of the Myers-Briggs Type Indicator (MBTI) and Cheek and Briggs’ Aspects of Identity Questionnaire (AIQ-IV). Based on their performance on MBTI, 90 learners with the extravert, introvert, and non-discriminating personality traits were selected from six classes and formed the three Extravert, Introvert, and Control (n1=n2=n3=30) groups. The students had taken a Specialized English course in the second semester of their BA program. The classes lasted 14 sessions. During the treatment, the researchers employed different activities for teaching ESP. After the instruction, the participants took the AIQ-IV. The results of ANCOVA indicated that the Introvert group gained significantly higher scores on the identity questionnaire than the Extravert and Control groups. The results of paired samples t-tests showed that while introverts had improved considerably in all components of the identity questionnaire, the Extravert and Control groups did not show any changes. The findings indicated that in interactive classroom environments, introvert learners had more inclination than the extravert and mixed introvert and extravert learners toward a shift in identity. The study has implications for ESP teachers, practitioners, and educators
The Effect of Topical Betamethasone Eye Drops on Postoperative Haze among Patients Undergoing Corneal Collagen Cross-Linking: a Randomized, Double Blind Placebo Controlled Study
Objective: To evaluate the effect of topical betamethasone eye drops on postoperative haze among patients undergoing corneal collagen cross-linking (CXL). Patients and Methods: Patients with mild to moderate keratoconus, aged 18 to 30 years, who were a candidate for CXL treatment and had the evidence of disease progression based on topographic findings entered the present study. One eye of each patient randomly received betamethasone and topical antibiotics after CXL and the other eye received topical antibiotics and placebo in place of betamethasone. The eyes were compared regarding BCVA, UCVA, refraction, keratometric and pachymetric findings using Pentacam, as well as changes of corneal haze using confocal microscopy, before CXL as well as one month and six months after CXL. Results: There was no difference in BCVA, UCVA, refraction, keratometric and pachymetric findings between the two groups before and six months after surgery. Based on confocal findings, the difference in light reflectance intensity between the case and control groups was statistically significant in anterior (P = 0.021) and posterior (P = 0.017) corneal stroma one month postoperatively, indicating higher haze in the placebo group. This difference was also statistically significant in anterior (P = 0.001) mid (P = 0.002) and posterior (P = 0.002) stroma six months postoperatively.Conclusion: Betamethasone had no effect on visual acuity, refraction, keratometric and pachymetric findings six months after CXL. It reduced corneal haze in both the first and the sixth months postoperatively. Keywords: Keratoconus; Cornea; Cross-Linking; Haze; Betamethason
Tablet, Flashcard and SMS and their Effects on EFL Learners' Attitudes and Vocabulary Knowledge
The purposes of this study were to compare the effects of using SMS, tablet and flashcard on the
EFL learners‟ attitudes and vocabulary learning. The participants of the study were 45 Iranian
advanced EFL learners, who were divided into three groups, each with 15 participants. The first group
learned the vocabulary items via tablet, the second group learned them via SMS, and the third one
learned the vocabulary items via flashcard. Three instruments were used in this study: a pretest of
vocabulary, a posttest of vocabulary, and an attitude questionnaire. The results revealed that vocabulary
instruction via SMS, flashcard, and tablet was effective in improving the participants‟ performance on
the vocabulary test; however, the highest mean on the posttest was obtained by students who received
vocabulary instruction through tablet. The results also showed that the majority of the learners in the
SMS group found reading texts on mobile phone‟s tiny screen troublesome and preferred to receive
English words via email rather than SMS. Majority of the learners in the flashcard group considered
flashcard effective for learning English words arguing that flashcards could be used on the move and
provide flexible learning anywhere, anytime. Learners in the tablet group reported that tablet learning
increased their motivation and was effective for learning English words. This study recommends that
instructors consider language learners‟ attitudes towards various methods of vocabulary learning
PRODUCT-BASED, PROCESS-BASED, AND GENRE-BASED INSTRUCTIONS IN EXPOSITORY WRITING: FOCUSING ON EFL LEARNERS’ PERFORMANCE AND STRATEGY USE
This explanatory sequential mixed methods study compared the effects of three different approaches to writing (product, process, genre) in the quantitative phase. In the qualitative phase, it focused on the type and frequency of strategies employed by learners in each group by employing think-aloud protocols. Three intact groups (n1=25, n2=23, n3=24) who were selected based on convenience sampling took part in the study. The participants had taken an essay writing course in the fifth semester of their study in English Translation. First, the participants took a Nelson English language proficiency test and then sat for a writing pretest. Content Scoring Guide (Ashwell, 2000) was the rating scale for scoring the essays. The inter-rater reliability between the two raters (r=0.75) showed that they were consistent in their scoring. After verifying the homogeneity of the groups regarding language proficiency and writing ability, the researchers assigned them randomly to three types of writing instruction; namely product-based, process-based, and genre-based groups. The treatment took 12 sessions, and distinct techniques related to each writing approach were employed in the classes. After the treatment, the participants took a writing posttest. The two raters scored the essays (inter-rater reliability=0.79). The results of the one-way ANOVA revealed a statistically significant difference between the groups. Scheffe post hoc test showed that the genre-based group outperformed the other two groups. However, no significant differences were found between the product-based and process-based groups. In the second phase of the study, 12 participants (four individuals from each group) participated in the think-aloud sessions to clarify the type of strategy they used while writing. Mu’s (2005) taxonomy of ESL writing strategies was employed as the criterion for classifying the strategies. The study has implications for language teachers and educators who are seeking the best way to teach writing. Syllabus designers can also benefit from the findings when developing materials for writing classes. Article visualizations
Planification technico-économique de la production décentralisée raccordée aux réseaux de distribution
In the recent years, there is a worldwide wave of considerable changes in power industries, including the operation of distribution networks. Deregulation, open market, alternative and local energy sources, new energy conversion technologies and other future development of electrical power systems must pursue different goals. Also growth in the demand and change in load patterns may create major bottlenecks in the delivery of electric energy. This would cause distribution system stress. The complexity of the problems related to distribution systems planning is mainly caused by multiple objectives. It is predicted that Distributed Generation (DG) will play an increasing role in the electrical power system of the future, not only for the cost savings but also for the additional power quality. Careful coordination and placement of DGs is mandatory. Improper placement can reduce DGs benefits and even jeopardize the system operation and condition. This thesis discusses the effects of DG implementation under different distribution system conditions and states not only to decrease system costs and losses but also to improve power quality, system voltage and line congestion. Three methodologies included mathematical model to obtain the optimal DG capacity sizing and sitting investments with capability to solve large distribution system planning problem. These frameworks have allowed validating the economical and electrical benefits of introducing DG by solving the distribution system planning problem and by improving power quality of distribution system. DG installation increases the feeders? lifetime by reducing their loading and adds the benefit of using the existing distribution system for further load growth without the need for feeders upgrading. More, by investing in DG, the DISCO can minimize its total planning cost and reduce its customers? bills.Dans un contexte de dérégulation du marché de l'énergie électrique, une arrivée massive de GED, Génération d'Energie Dispersée (les éoliennes, la biomasse, les micro-turbines, les piles à combustibles, les panneaux solaires, ...) au niveau de la Haute Tension de niveau A (HTA, principalement 20/33 kV) et de la Basse Tension (BT, principalement 400/230V) est à prévoir.De nombreux avantages, techniques et économiques, justifient le développement de ce type de production, parmi lesquels nous relevons les suivants: la production d'énergie plus près des consommateurs d'où une baisse des coûts de transport et de distribution, ainsi que la réduction des pertes dans les lignes; la substitution de l'énergie conventionnelle «polluante» par des énergies nouvelles plus «propres» et silencieuses; un intérêt économique très important pour les exploitants de GED grâce aux subventions accordées; en matière de planification, face à une augmentation de la charge, l'insertion de GED sur le réseau de distribution permet d'éviter la construction de nouvelles lignes HTB; la plus grande facilité de trouver des sites pour installer de petits générateurs; le temps d'installation relativement court de GED; pour l'alimentation de sites isolés, il peut être plus rentable d'alimenter un réseau de distribution local avec des GED plutôt que de le relier à un poste HTB/HTA lointain ; la cogénération, une des formes de GED la plus répandue, améliore le rendement énergétique. Cette thèse traitera des points suivants : brève description des réseaux de distribution ; présentation d'une méthodologie systématique d'optimisation de la planification des réseaux de distribution incluant la GED ; étude des effets des paramètres des réseaux sur l'insertion de GED ; étude systématique des impacts de GED sur le réseau