34 research outputs found
Fluid Structure Interaction (FSI) Based Wind Load Modelingfor Dynamic Analysis of Overhead Transmission Lines
No full textNote:Electricity is a crucial form of energy in our societies, and transmission lines are key elements to ensure the reliability of electric power grids. Continuity of service is the main preoccupation of electric utilities, and this continuity may be disrupted by a large variety of sources and accidents. Transmission lines, by their intrinsic topology, remain the grid components that are the most exposed to climatic sources of disruption. The most common and important source of dynamic loads on transmission lines results from wind effects on the towers and conductors. Conductors are particularly sensitive to wind effects as they are long and relatively flexible (compared to their supports) and are literally wind-catching structures in the power grid infrastructure. In cold climates, wind and ice have compounding effects on lines and give rise to the most severe design loading conditions. Therefore accurate prediction of the wind pressure on overhead conductors is essential to conduct a reliable assessment of the ine response, in terms of both electrical clearances and conductor loads transferred to supports. Spatial randomness of wind loads on overhead lines has already been addressed by stochastic analysis methods and is now taken into account in design with the use of so-called span factors. Further reasonable gains in wind load accuracy can be obtained by examining the physics of wind effects on conductors, in both non-iced and iced conditions, with improved predictions of lift and drag forces determined from fluid-structure interaction (FSI) analysis. The traditional design method to apply wind load on transmission lines is to convert the design wind speed to a static pressure through Bernoulli 's equation where the pressure is proportional to the air density and the squared wind speed. In this approach the fluid-structure interaction of wind and line components is ignored: wind is considered as a quasi-static load on conductors and supports, while special instability effects due to particular wind conditions suc as vortex shedding (Aeolian vibrations) and flutter (cable galloping) are accounted for separately with specific mitigation solutions if necessary. In gusty wind conditions with high turbulence intensity, conductors may experience large horizontal displacements that affect their surrounding wind flow. A physically accurate wind load evaluation on conductors is possible by computational wind-structure interaction analysis. To date, largely due to its high computational cost and the lack of experimental data to validate computational models, an advanced fluid-structure analysis framework for wind-cable interaction has not been developed. In this study a new approach based on FSI analysis to evaluate equivalent wind loads on conductors is developed. The first step in such an approach is accurate evaluation of wind pressure on conductor. For this purpose the FSI analysis is carried in two dimensions where the detailed bare and iced conductor section geometry and surrounding air flow are modeled, considering a gi en incident wind speed. The conductor cross section is assumed to be supported on flexible supports to study the interaction between the conductor motion and the air flow. FSI analysis yields both the fluid and structure response. Of particular interest is the wind pressure field on the conductor section, which allows the computation of the resultant drag and lift forces. This process is repeated for several cross sections along the span and the resulting forces provide the effective span wise wind load distribution on the conductor. This wind loading is then used as input in a separate 3-D computational nonlinear dynamic analysis model to predict the line response. This dynamic analysis of the line section can be detailed to represent very realistic line sections including conductors, suspension links and supporting towers. It should be emphasized that the author does not advocate the "complexification" of overhead line wind analysis with the introduction of FSI and dynamic computational simulations in engineering offices. It is rather proposed to use these advanced computational methods, in a research and development context, to evaluate and possibly improve current wind analysis methods. Another very interesting application of this computational technique relates to optimized cross-sectional design of conductors, in terms of geometry and surface roughness. Detailed FSI analysis also enables the evaluation of aerodynamic damping of various cable geometries. As many Canadian utilities are reassessing the reliability levels of their transmission infrastructure and making difficult investment decisions, a more realistic wind loading model could be of high value. Key words: Overhead transmission line wind loading; fluid-structure interactions; computational fluid dynamics; conductor lift and drag coefficients; interactive wind and ice effects; overhead line conductorsNos societes sont fortement dependantes de l'electricite, et il ne fait pas de doute que la fonctionnalite des !ignes de transport est determinante pour assurer la fiabilite des reseaux electriques modemes. En effet, la continuite de l'approvisionnement en electricite reste la preoccupation majeure de toutes les compagnies d'electricite, et cette continuite du service peut etre compromise par une multitude d'incidents ou d'accidents sur !'ensemble du reseau. Les !ignes de transport sont toutefois les composants du reseau qui sont les plus exposes aux charges climatiques ou environnementales susceptibles de declencher des pannes. Parmi toutes les sources possibles de charges dynamiques sollicitant les !ignes de transport, celles provenant des effets du vent sur les pylones et les conducteurs restent les plus frequentes. Les conducteurs de !ignes sont particulierement vulnerables aux effets du vent car les portees sont longues et flexibles (compare aux pylones) et leur presence physique dans le reseau en font ds structures exposees a toutes les intemperies qui peuvent survenir sur le territoire couvert. Cette vulnerabilite est encore plus grande dans les climats nordiques ou les effets combines du givrage atmospherique et du vent creent des scenarios de charges de conception parmi les plus critiques et done susceptibles de controler la conception finale des !ignes. Il nous apparait done essentiel de comprendre la dynamique des fluides des effets du vent pour predire avec realisme et un degre de precision raisonnable la pression du vent exercee sur les conducteurs. Une meilleure evaluation des charges dues au vent permettrait par le fait meme des predictions plus realistes de la reponse des lignes aux charges de vent, non seulement en terme de deplacements et degagements electriques mais aussi en terme des charges nettes transferees aux pylones par les conducteurs. La nature aleatoire des effets du vent sur les conducteurs a deja fait l'objet de nombreuses etudes scientifiques et les methodes d'analyse stochastique modemes permettent de cemer la question: les methodes de conception simplifiees qui sont suggerees dans les normes et guides tiennent compte de ces effets en utilisant un coefficient de portee global qui ajuste a la baisse les efforts calcules au pylone sous des charges supposees synchrones et uniformes le long des conducteurs. Cette recherche ne conceme pas cet aspect de la question. Nous croyons que des gains de precision appreciables dans la prediction des charges de vent sur les lignessont possibles par une meilleure modelisation de la physique des effets du vent sur les conducteurs, dans les conditions givrees ou non, en utilisant les techniques d'analyse qui tiennent compte des interactions dynamiques fluide-structure. Ces interactions sont ignorees dans les methodes d'analyse conventionnelles qui consistent simplement a calculer une pression statique proportionnelle a la vitesse carree du fluide selon l' equation classique de Bemouilli. Bien sur, les concepteurs ne negligent pas la consideration des vibrations eoliennes ou du galop des conducteurs, mais ces phenomenes sont traites separement et n'influencent pas le calcul des charges sur les pyl6nes. Dans cette recherche, nous nous interessons aux conditions de vent de rafale avec grande turbulence qui caracterisent les tempetes de vent. Ces vents forts et turbulents creent de grands deplacements des conducteurs qui modifient les conditionsd'ecoulement d' air. Une evaluation plus precise de ces conditions est possible par analyse computationnelle des interactions vent-conducteur. Les bases theoriques de la physique des phenomenes en presence sont connues mais aucun cadre d'application numerique n'a ete propose a date, en partie a cause des couts numeriques eleves mais aussi du au manque de donnees experimentales pouvant valider ces modeles computationnels. Nous avons developpe un tel cadre d' analyse computationnelle dans cette recherche et 1' avons illustre dans un cycle complet, du calcul des charges au calcul de la reponse d'une section de ligne, avec plusieurs exemples pratiques a chacune des etapes de developpement. L'etape initiate consiste a determiner precisement le champ des pressions exercees a la surface d 'un conducteur de ligne a partir de modeles en deux dimensions qui rendent la reponse detaillee d 'une section de conducteur sur supports flexibles dans un ecoulement d'air a vitesse de vent incidente donnee. Une analyse CFD (dynamique des fluides computationnelle) du domaine fluide, l'air en mouvement entourant le conducteur, procede interactivement avec une analyse des deplacements de la section de conducteur, pour determiner les forces nettes (trainee et portance) agissant a !'interface airconducteur. Le processus est repete a volonte pour differentes conditions de support duconducteur ( correspondant a diverses positions le long de la portee) et pour une serie temporelle de conditions de vitesse de vent incident. Au final, on peut ainsi calculer un historique des forces dues au vent sur une portion tributaire de la portee jugee representative et utiliser ces forces comme des charges extemes sur des modeles d'analyse dynamique non lineaire de sections de lignes en trois dimensions. Ces analyses peuvent etre detaillees a souhait pour determiner la reponse dynamique des conducteurs, accessoires d'attache et pylones sous vents turbulents. Nous insistons sur le fait que nous ne suggerons pas une complexification de !'analyse des !ignes de transport sous les effets du vent dans les bureaux d'etudes a !'aide de modeles dynamiques sophistiques combinant les interactions des domaines fluides et solides. Nous proposons plutot d' utiliser le cadre computationnel mis a l'epreuve danscette recherche dans un contexte de recherche et developpement pour evaluer et possiblement ameliorer les methodes statiques conventionnelles. Une autre application interessante conceme la conception optimisee de la geometrie des conducteurs de lignes en termes de proprietes aerodynamiques. Mots cles: vent sur les !ignes aeriennes de transmission; interactions fluide-structure ; dynamique des fluides computationnelle ; coefficients de trainee et de portance des conducteurs ; interactions vent et givre
A phenomenological study of the process of ICT-competence of Iranian teachers with the purpose of presenting a native model
No full textBackground and Objectives: Research findings about the application of information and communication technologies in classroom has shown that despite the efforts had been done and the large amount of costs spent for empowering teachers' computer skills, but these activities have not been able to create desired changes in the role and activity of teachers in schools. Therefore, the purpose of the present study was to study the phenomenological process of Iranian teachers' ICT competence in order to present a native model. Methods: This was a qualitative phenomenological research, because the lived experiences of teachers in achieving technological competence in the classroom have been used to explore the objectives of the study. The statistical population of this qualitative study were all teachers in Urmia city. 22 teachers (13 females and 9 males) were selected by non-probability purposeful sampling method with considering the desired characteristics and theoretical saturation based-rule. Participants who engaged in 17 different schools including public, board of trustees, smart, nonprofit, and rural schools, were selected. The data collection tool was semi-structured interview. Voice recording and note-taking (with emphasis on voice recording), as Two techniques for gathering data, were used. George's (1970) four-step coding approach were used to analyze the data. The coding process was performed in MAXQDA10 software. Findings:The findings of the qualitative analysis indicated that the process of teachers ICT-competence can be organized into five components, including; 1) motivation/ tendency/ interest in teachers including the following sub-components: “Changing in teacher’s salary”, “Changing teachers’ position”, “Create need”, “Classification of teachers based on the prior knowledge”, “Pay attention to the timing of the courses” , “Changing the look to the teaching profession” and “Choosing the right professor”; 2) planning, including the following sub-components: “Teachers Rating (Needs Assessment)” , “Determining curriculum (educational topics)”, “Choosing the right professor”, “Locate the right place” and “Determine the right time”; 3) beginning of the learning process including the following components: “Hardware training”, “Software training”, “Problem-solving training”, “Information literacy training”, “Facilitate access to educational resources” and “Support”; 4) implementation of the learning process including the following sub-components: “In-service preparation courses”, “In-service training courses”, “Specialized school courses”, and “Out-of-school courses” and 5) " institutionalization of technology competence " including the following sub-components: “Problem-solving training’, “Formalize collaboration between teachers” and ‘Formalize follow-up courses for teaching and learning”. Conclusion: This model is presented by looking at the needs of teachers, the conditions and Organizational structure of education, the facilities of schools, the status of courses, the cooperation between teachers, and so on. In this model, all the influential factors in the process of acquiring information and technology competence by teachers have been included and based on the content of the interviews, each of them has been considered in the relevant step. Although it could be organized these components or steps in hierarchical or step-by-step structure, but in many places it is possible to go back and start from the previous step. It is hoped that this model will be a step towards developing an appropriate model in the field of staff technology competence for the Education Organization and other organizations.
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A Projected Inverse Dynamics Approach for Multi-arm Cartesian Impedance Control
No full textLin H-C, Smith J, Kouhkiloui Babarahmati K, Dehio N, Mistry M. A Projected Inverse Dynamics Approach for Multi-arm Cartesian Impedance Control. In: IEEE/RSJ Int. Conf. on Robotics and Automation. 2018.We propose a model-based control framework for
multi-arm manipulation of a rigid object subject to external
disturbances. The control framework, based on projected inverse
dynamics, decomposes the control law into constrained
and unconstrained subspaces. Unconstrained components accomplish
the motion task with a desired 6-DOF Cartesian
impedance behaviour against external disturbances. Meanwhile,
the constrained component enforces contact and friction constraints
by optimising for contact forces within the constrained
subspace. External disturbances are explicitly compensated for
without using force/torque sensors at the contact points. The
approach is evaluated on a dual-arm platform manipulating a
rigid object while coping with unknown object dynamics and
human interaction
College of Pharmacy, University of Utah, Class of 1991. "Senior Banquet" Invitation
No full textCollege of Pharmacy, University of Utah, Class of 1991. "39th Annual Senior Banquet" Invitation. Tuesday, June 4, 1991, 6:30 pm. Dinner. Introductions: Dwight S. Fullerton, Dean. Preceptor of the Year Award: Mr. Kevin Flanary, Syntex Laboratories, Inc. Dean L. David and Janet C. Hiner Distinguished Pharmacy Alumni Award: William Hoge, President, College of Pharmacy Alumni Association. Adjournment. Guest Sponsors: AMFAC Drug Supply Co., Bergen Brunswig Drug Co., McKesson & Robbins Drug Co. Pharmacy Graduates 1991: Adams, Val; Ames, Michelle; Barker, Brian; Clarke, Ralph; Cypers, Michele; Entezam, Gita; Erickson, Victor; Gladson, Michael; Gordon, Jay; Gorman, Michael; Harris, Julie; Haynes, Paul; Horsley, Julie; Jenson, Angela; Keramati, Azra; Kim, Evelyn; Kinjo, Mariko; Kitamura, Emily; Koohgivi, Keyhan; Le, Hang; Le, Hau; Lester, Patrick; Macy, Michele; Madsen, Jeffrey; Maughan, Scott; Mecham, Scott; Mitsunaga, Tami; Nguyen, Van; Norman, Janet; Olson, Robert; Parks, Troy; Payvarmehr, Mahnaz; Pokrant, Cynthia; Rechis, Douglas; Rodriguez, Pamela; Russell, Kimberli; Sharma, Raju; Sondrup, Todd; Spriggs, Shawn; Stevenson, James; Tinkham, Phillip; Urquidi, Yvette; Whitney, Angela; Widdowson, Craig; Woodward, Jane; Zoolakis, Anthony
Critical Analysis of Grammatical Metaphor of Nominalization in English and Persian Political Discourses
No full textNominalization is one of the metaphors introduced by Halliday, which is a part of ideational meta-function. The present research study is an attempt to investigate the role of nominalization in political Persian and English discourses from Van Dijk’s Critical Discourse Analysis (CDA) perspective. In so doing, it attempts to answer the following research questions: (1) Does nominalizations have any role in cohesion and coherence as well as in marginalization and highlighting in the text? (2) What’s ideological role of nominalization in Persian and English political discourse? (3) In which discourse (Persian or English) more nominalizations are used? By studying 22/5 pages of English newspapers (Guardian, USA Today, Telegraph and New York Times) and 22/5 pages of Persian newspapers (Keyhan, Qods and Shargh) focused principally on Iran’s nuclear program negotiations, it was discovered that nominalization can cause marginalization and highlighting by changing information construction of the sentence (theme and rheme), referring to presuppositions, using entailment, omitting the agent and changing the mental models. Nominalization helps the author to make reference to the background knowledge of the reader without giving any repetitive information (coherence). It also helps the writer to use nouns (next to each other) which have the same conceptual meaning (cohesion). Furthermore, it can be concluded that this metaphor is used more frequently in Persian newspapers than in English ones
The more accurate determination of surface excitation parameters, the more accurate quantitative surface analysis
No full textZygomatic implants placed in atrophic maxilla: an overview of current systematic reviews and meta-analysis
No full textBackground Zygomatic implants are a treatment option for severely atrophic maxilla. Main text This study aimed to summarize and evaluate systematic reviews assessing the clinical outcomes of zygomatic implants including survival/failure rate and complications. PubMed-MEDLINE, Google Scholar, LILACS, and the Cochrane Database were searched up to April 2020. Risk of bias assessment was conducted by the AMSTAR tool. Initial searches yielded 175 studies. These were assessed, and following title abstract and full-text evaluation, 7 studies (2 meta-analyses) were included in the final review. According to the AMSTAR tool, 1 was deemed high quality, 4 were classified as medium, and 2 as low quality. The mean AMSTAR score (+/- SD) was 5.28 of 9 (+/- 2.36) ranging from 2/9 to 9/9. The reported survival rates ranged from 95.2 to 100 except for resected maxillas, which established higher failure rates up to 21.43. Concerning the complications with the zygomatic implants, various surgical and prosthetic complications were reported with sinusitis being the most frequently observed complication. Zygomatic implants appears to offer a promising alternative to formal bone grafting techniques with lower costs, less complications, less morbidity, shorter treatment times, and comparably high survival rates. Conclusion Complications were rare and usually easy to manage. However, the treatment should be directed by appropriately trained clinicians with noticeable surgical experience
Protein expression on Cr resistant microorganism using electrophoresis method
No full textAbstrak. Fatmawati U, Suranto, Sajidan. 2009. Ekspresi protein pada mikroorganisme resisten Cr dengan metode elektroforesis.
Nusantara Bioscience 1: 31-37. Krom heksavalen (Cr(VI)) dikenal sebagai logam berat beracun, sehingga perlu direduksi menjadi
Cr(III) yang lebih rendah toksisitasnya. Pseudomonas aeruginosa, Pseudomonas putida, Klebsiella pneumoniae, Pantoea sp. dan
Saccharomyces cerevisiae adalah mikroorganisme resisten dan mampu mereduksi Cr(VI). Tujuan penelitian ini adalah mengetahui
kemampuan mikroorganisme dalam mengurangi Cr(VI) dan mengetahui pola pita protein antara mikroorganisme resisten Cr(VI) dan
mikroorganisme tidak resisten yang diinokulasi pada medium kaldu LB. SDS-PAGE digunakan untuk mengetahui ekspresi protein,
sementara konsentrasi Cr(VI) diidentifikasi dengan metode 1,5 difenilkarbazid. Data kuantitatif dianalisis dengan ANAVA dua faktorial
dilanjutkan dengan uji jarak berganda Duncan pada taraf 1%. Data kualitatif yaitu ekspresi protein dianalisis dengan mobilitas relatif
(Rf). Hasil penelitian menunjukkan bahwa kemampuan mikroorganisme dalam mereduksi Cr(VI) pada konsentrasi awal 0.5 ppm, 1 ppm,
5 ppm dan 10 ppm berbeda-beda, persentase rata-rata kemampuan masing-masing mikroorganisme dalam mereduksi Cr(VI) adalah: P.
putida (65%) > S. cerevisiae (64,45%) > P. aeruginosa (60,73%) > Pantoea sp. (50,22%) > K. pneumoniae (47,82%) > tanpa
mikroorganisme (34,25%). Penambahan mikroorganisme secara nyata mempengaruhi reduksi Cr(VI). SDS-PAGE menunjukkan bahwa
ekspresi protein antara mikroorganisme resisten dan tidak resisten tidak berbeda, tetapi mikroorganisme resisten memiliki lebih banyak
protein (pita protein lebih tebal).
Kata kunci: logam berat Cr, mikroorganisme, protein, elektroforesis
Dynamic-Assisted Navigational System in Zygomatic Implant Surgery: A Qualitative and Quantitative Systematic Review of Current Clinical and Cadaver Studies
No full textPurpose: The goal of this systematic review is to assess the accuracy and complications (including failure) of dynamic navigation in placing zygomatic implants. Methods: PubMed, Cochrane Library (CENTRAL), trial register (clinicaltrial.gov), and Google Scholar were searched systematically up to May 2020. In addition, the reference lists of included systematic reviews were hand searched. The New Castle Ottawa and Joanna Briggs Institute Critical Appraisal Checklist for Case Reports were used for quality assessment. Results: Ninety-four studies were assessed, and finally, 12 articles were included. According to Joanna Briggs Institute tool, the mean score of case reports (+/- standard deviation) was 6.4 (range, 5/9 to 8/9) and the mean score of observational studies (+/- standard deviation) was 5.66 (range, 5/9 to 7/9) as measured by New Castle Ottawa tool. Included materials pointed out that higher accuracy and drastic cut down on the risk of perioperative/postoperative complications were reported by using the dynamic navigation system compared with freehand implant placement. Conclusions: Application of dynamic navigation systems is a reliable technology for zygomatic implant placement, especially in difficult cases with a history of maxillary deficiency. Evidence of reliability and accuracy of dynamic navigation technique in multicenter large randomized and prospective controlled studies is still lacking. (C) 2020 American Association of Oral and Maxillofacial Surgeon
A new control strategy for a bidirectional qZSI as an interlink converter in a hybrid AC/DC microgrid
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