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- 저자 : Jara, Diego Chavez (검색결과 16 건)
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Use of Sliding Multirotational Devices of an Irregular Bridge in a Zone of High Seismicity
José M. Jara,Manuel Jara,Hugo Hernández,Bertha A. Olmos 대한토목학회 2013 KSCE JOURNAL OF CIVIL ENGINEERING Vol.17 No.1
The 525 meters long Infiernillo II bridge crosses the Infiernillo Dam and it is the first isolated bridge built in Mexico. It is located in the Morelia-Lazaro Cardenas highway that connects the central cities of the country to the Pacific Coast. Arch steel trusses compose the superstructure of the five simple supported spans. The substructure consists of reinforced concrete abutments and piers supported on cylinders and piles. The total cylinder-pier subsystem height is in the range of 46 m to 71 m, causing a strong irregularity in the transverse and longitudinal directions. The bridge was subjected to an assembly of real strong motion movements recorded close to the Pacific Coast in Mexico, site where the most severe earthquakes occur in the country. The study started by evaluating the analytical model with environmental vibration measurements previously taken. Based on the similarity of the results,none adjustment was required for the numerical model. The results show the importance of the isolator dynamic characteristics on the expected seismic behavior of the bridge. Special emphasis is dedicated to analyze the effectiveness of the isolation system for avoiding concentration of strength and displacement ductility demands on an irregular bridge substructure.
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Jara, Diego Chavez,Jang, Ho Elsevier 2019 Wear: An international journal on the science and Vol.430 No.-
<P><B>Abstract<SUP>1</SUP> </B></P> <P>Tribological properties of the brake friction material including straight phenolic resin with different molecular weighs (Mw), and potassium titanate with different morphologies (platelet and whisker), were investigated. Results showed that the friction coefficient and wear rate were strongly affected by the contact plateaus on the friction material surface. At low temperatures, before the thermal decomposition of the resin, the friction materials with high-Mw resin and platy potassium titanate yielded improved friction and wear resistance characteristics, which were attributed to the large plateaus on the sliding surface. On the other hand, at temperatures higher than the thermal decomposition temperature, the friction materials comprising high-Mw resin and potassium titanate whisker yielded higher friction levels and lower wear rates. These changes were supported by increased activation energies and the facilitation of secondary contact plateaus by potassium titanate reinforcements. The presence of the contact plateaus also affected the size distribution of the wear debris. At temperatures lower than the thermal decomposition temperature, high-Mw resin produced larger wear debris, whereas friction materials with potassium titanate whisker produced larger wear particles at higher temperatures. These findings suggest that it is possible to tailor brake emissions by considering the synergistic effects of the constituent ingredients.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Synergy was found by binder resin and titanate reinforcement for friction and wear. </LI> <LI> Molecular weight of resin changed the decomposition temperature of the brake pad. </LI> <LI> Potassium titanate morphology influenced the size of secondary contact plateaus. </LI> <LI> Secondary contact plateaus affected the size distribution of wear debris. </LI> </UL> </P>
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Santaclara, Jara G.,Olivos-Suarez, Alma I.,Gonzalez-Nelson, Adrian,Osadchii, Dmitrii,Nasalevich, Maxim A.,van der Veen, Monique A.,Kapteijn, Freek,Sheveleva, Alena M.,Veber, Sergey L.,Fedin, Matvey V. American Chemical Society 2017 Chemistry of materials Vol.29 No.21
<P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2017/cmatex.2017.29.issue-21/acs.chemmater.7b03320/production/images/medium/cm-2017-03320d_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm7b03320'>ACS Electronic Supporting Info</A></P>
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Direct Visual Servoing Framework based on Optimal Control for Redundant Joint Structures
Jorge Pomares,Carlos Alberto Jara,Javier Pérez,Fernando Torres 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.
This paper presents a new framework based on optimal control to define new dynamic visual controllers to carry out the guidanceof any serial link structure. The proposed general method employs optimal control to obtain the desired behaviour in the joint spacebased on an indicated cost function which determines how the control effort is distributed over the joints. The proposed approachallows the development of new direct visual controllers for any mechanical joint system with redundancy. Finally, authors showexperimental results and verifications on a real robotic system for some derived controllers obtained from the control framework.
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( Franz Albert Go ),( Raul Jara ) 대한내과학회 2014 대한내과학회 추계학술발표논문집 Vol.2014 No.1
Background: Transient bundle branch block has been defi ned as an interventricular conduction defect that subsequently returns, to normal conduction. Of particular concern is the severe coronary artery disease etiology of this particular phenomenon which may have a diagnostic as well as prognostic value in such patients and may modify subsequent management strategies. Case: We present a case of transient left bundle branch block occurring in 60 year old female patient who presented with intermittent chest pain. First ECG on consult revealed sinus rhythm with complete left bundle branch block. A repeat ECG on follow up demonstrated an initial CLBBB pattern at lead 1 then reverting back to Narrow QRS sinus rhythm on the succeeding leads. Resting echocardiogram showed concentric left ventricular remodelling with normal wall motion, contractility and systolic function with grade 1 diastolic dysfunction. Dobutamine stress was performed revealing normal result with 88% MHR with no stress-induced ischemia. Hence, a coronary angiogram was done showing 3 vessel disease with signifi cant left main coronary involvement. She underwent CABG which remarkably improved her angina symptoms. Conclusions: This case report shows an unusual case of severe CAD presenting as transient CLBBB. The clinical presentation may be obvious clinically but certain diagnostic tests, particularly plain and stress echocardiogram, which can aid the physician in the diagnosis, may miss out the exact diagnosis. While a non-invasive echocardiogram is preferred over an invasive coronary angiogram for CAD workup, it is noteworthy to emphasize that a good history and physical examination with aid of conventional 12 lead ECG can guide physicians as to subsequent workup of this particular case.
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( Jaime Aherrera ),( Paul Reganit ),( Felix Punzalan ),( Raul Jara ),( Ramon Abarquez ) 대한내과학회 2014 대한내과학회 추계학술발표논문집 Vol.2014 No.1
Introduction: A 12 lead electrocardiogram continues to be the most frequently ordered test in cardiology. In third world countries where access to 2D echocardiogram is limited, the value of the ECG as a tool in determining patients with depressed ejection fraction (EF) should be investigated. We aim to compare the computed ejection fraction by electrocardiogram with the ejection fraction taken from a transthoracic 2D echocardiogram in patients with an echocardiogram derived EF < 50%. Methods: Patients with an echocardiographically derived EF of < 50% were be included. The EF by ECG was computed using the formula = (2.264 x aVR QRS amplitude) + (age x 0.645). Descriptive statistics was used to present Results: Since age of the patient is used to derive the EF by ECG, data would be further stratifi ed by age group. Results: A total of 129 participants were included in the analysis. The EF computed by ECG using aVR was less than 50% in 71%. The mean EF taken by 2D echocardiography was 37% (SD: 8%), while the mean EF computed using ECG was 44.5% (SD: 10%). The sensitivity and specifi city of ECG to detect a severely depressed ejection fraction (<35%) was also determined at 39% and 86%, respectively. Among those 40 years old and below, the sensitivity and specifi city of an ECG to predict an EF < 35% is 100% and 20%, respectively. Among those older than 40 years old, the sensitivity and specifi city was 20% and 96%, respectively. Conclusion: Previous studies have repeatedly demonstrated the importance of LVEF. A rapid and readily available estimation method of EF is crucial in the management of the vast majority of cardiac patients, especially in third world countries.
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