oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2020 ( 3 )

2019 ( 19 )

2018 ( 29 )

2017 ( 27 )

Custom range...

Search Results: 1 - 10 of 15825 matches for " Miguel Sequera "
All listed articles are free for downloading (OA Articles)
Page 1 /15825
Display every page Item
On MEMS Reliability and Failure Mechanisms
Daniel J. Fonseca,Miguel Sequera
International Journal of Quality, Statistics, and Reliability , 2011, DOI: 10.1155/2011/820243
Abstract: Microelectromechanical systems (MEMS) are a fast-growing field in microelectronics. MEMS are commonly used as actuators and sensors with a wide variety of applications in health care, automotives, and the military. The MEMS production cycle can be classified as three basic steps: (1) design process, (2) manufacturing process, and (3) operating cycle. Several studies have been conducted for steps (1) and (2); however, information regarding operational failure modes in MEMS is lacking. This paper discusses reliability in the context of MEMS functionality. It also presents a brief review of the most relevant failure mechanisms for MEMS.
On MEMS Reliability and Failure Mechanisms
Daniel J. Fonseca,Miguel Sequera
Journal of Quality and Reliability Engineering , 2011, DOI: 10.1155/2011/820243
Abstract: Microelectromechanical systems (MEMS) are a fast-growing field in microelectronics. MEMS are commonly used as actuators and sensors with a wide variety of applications in health care, automotives, and the military. The MEMS production cycle can be classified as three basic steps: (1) design process, (2) manufacturing process, and (3) operating cycle. Several studies have been conducted for steps (1) and (2); however, information regarding operational failure modes in MEMS is lacking. This paper discusses reliability in the context of MEMS functionality. It also presents a brief review of the most relevant failure mechanisms for MEMS. 1. Introduction Microelectromechanical systems (MEMS) are a relatively new and fast-growing field in microelectronics. MEMS are commonly used as actuators, sensors, and radio frequency and microfluidic components, as well as biocomposites, with a wide variety of applications in health care, automotive, and military industries. It is expected that the market for MEMS will grow to over $30B by 2050 [1]. The MEMS lifecycle can be divided into three basic steps: (1) the design process, (2) the manufacturing process, and (3) the operating cycle. Several research studies have been conducted for the design and manufacturing of MEMS; however, information regarding failure analysis for MEMS can still be considered in its infancy stage [2]. There is a need to develop new tools and methodologies to understand the behavior of MEMS devices for distinct applications and operation conditions. MEMS are extremely diverse and their failure modes can be unique under different conditions [3]. MEMS represent a technology that can be defined as miniaturized mechanical and electromechanical elements (i.e., devices and structures) that are made using the techniques of microfabrication. Dimensions of MEMS devices can vary from well below one micron on the lower end of the dimensional spectrum, all the way to several millimeters [4]. Likewise, the types of MEMS devices can vary from relatively simple structures having no moving elements, to extremely complex electromechanical systems with multiple moving elements under the control of integrated microelectronics. A main criterion of MEMS is that there are at least some elements having some sort of mechanical functionality, whether or not these elements can move [4]. MEMS are manufactured using batch fabrication techniques similar to those used for integrated circuits. Unprecedented levels of functionality, reliability, and sophistication can be placed on a small silicon chip at a relatively low cost
CHICKEN EMBRYO: A CARDIOVIDEOGRAM MODEL TO STUDY THE EXPERIMENTAL TOXICITY INDUCED BY Thevetia Peruvians.
Diana Sequera,José Miguel Ercolino,Marco álvarez
RETEL : Revista de Toxicología en Línea , 2010,
Abstract: Studies on the cardiotoxicity induced by chemical agents have been strengthened through the use of cardiogenic signals registration methods. In this study we used a method, defined in our laboratory as Cardiovideogram (CVG), reinforced with image analysis, to illustrate “in vivo” chick embryo heart the cardiotoxicity induced by aqueous extract of Thevetia Peruvians seeds, an ornamental plant with severe toxic action. The results showed that the aqueous extract of Thevetia Peruvians seeds induces Average Heart Rate (AHR) reduction in 70.49% measured in beats per minute (P/ min) through variations of brightness measurement in intervals between the peaks of this variation. These changes were associatedwith a higher Ventricular (V) and Truncus Arteriosus (TA) systolic level and a lower Atrial (A) systole level, compared to the control condition. It was shown that the cardiotoxicity induced by the aqueous extract of Thevetia Peruvians seed can be clearly analyzed in chick embryo cardiac model, strengthened with Cardiovodeogram (CVG) which is an alternative recording method for study of many other toxic agents with cardiotoxic potentially.
A Proposal of an E-Learning Inter-Operable Platform Based on Semantic Web  [PDF]
Jimmy Rosales Huamani, José Castillo Sequera, José Miguel Ca?amero, Fabricio Puente Mansilla, Gustavo Boza Quispe
Creative Education (CE) , 2015, DOI: 10.4236/ce.2015.68076
Abstract: Electronic learning, commonly called e-learning, has the goal of using technology to spread knowledge. Actually, the fast growing of Internet has allowed the creation of a variety of e-learning platforms. Thus there is the need for the regulation and interoperation of these platforms. Interoperability is a key factor in e-learning systems because it allows exchange and reuse of educational resources developed in different platforms. Problems may appear in their design and implementation because of the lack of interoperability among educative platforms contents. For that reason, it is important to use meaningful information to make possible the interoperability among different environments and to help in the management of proper contents. This is the area where Semantic Web may play a key role for reaching this goal. In this work, we propose the design of an e-learning platform prototype, that using semantic meaning, helps in the solution of interoperability problems.
Collaboration in the Cloud for Online Learning Environments: An Experience Applied to Laboratories  [PDF]
Washington Luna, José Luis Castillo Sequera
Creative Education (CE) , 2015, DOI: 10.4236/ce.2015.613144
Abstract: Nowadays, Cloud computing has become essential support for online education. Growth and interest in the massive open online courses (MOOCs) hosted on cloud, as well as the large number of students with own device (BYOD) set a favorable scenario for a new model of cooperation and interaction for online education. In this paper we present the results of collaborative work in the cloud, using Google Apps services and MOOCs, in conducting laboratory reports for the subjects of chemistry, and based on this experience we propose an architecture for platforms e-learning and mechanisms for collaborative work in cloud applied to the laboratories.
Ciudadanía y espacio público en la era de la globalización neoliberal
Sequera, Jorge,Janoschka, Michael
Arbor : Ciencia, Pensamiento y Cultura , 2012, DOI: 10.3989/arbor.2012.755n3005
Abstract: The profound economic, social and political reforms in contemporary migration societies are seriously tackling the scope of civil, social and political rights of citizenship. In this article, we refer to the concept of citizenship through four dimensions that enlarge its theoretical content and transcend the historical rationality of rights, duties and the State: (a) citizenship as a collective subject that is being permeated by (neoliberal) logics of producing urban spaces; (b) citizenship as a power relation expressed by politics of scale; (c) citizenship as a discursive mechanism that articulates identity and place through politics of belonging; and (d) citizenship interpreted through acts that challenge the multiple dimensions of domination. This conceptualisation helps to outline the conceptualisation of acts of citizenship that demand a re-appropriation of public space and, in general terms, the public sphere, aiming at constructing new spaces of citizenship. Las profundas reformas en las condiciones económicas, sociales y políticas actuales están afectando gravemente el alcance de los derechos civiles, sociales y políticos de la ciudadanía. Un concepto, el de ciudadanía, que es atravesado por las lógicas neoliberales de producción del espacio público así como por la lógica histórica Derecho- Deber-Estado. Pero este mismo concepto de diudadanía puede ser analizado desde tres novedosos aspectos teóricos que amplíen su dimensión y superen los anteriores: (a) la ciudadanía como una relación de poder que se expresa mediante políticas de escala; (b) la ciudadanía como mecanismo discursivo que articula identidad y lugar a través de las políticas de pertenencia; y, (c) la ciudadanía interpretada a través de actos que desafían las múltiples relaciones de dominación. Estas tres dimensiones nos ayudarán a comprender los actos de ciudadanía que demandan la reapropiación de la esfera y del espacio público con el fin de construir nuevos espacios de ciudadanía.
Del movimiento vecinal a las movilizaciones por una vivienda digna en Madrid. De la necesidad hecha derecho al derecho hecho necesidad
Jorge Sequera Fernández
Nómadas , 2011,
Abstract: Este artículo trata de identificar las diferencias y semejanzas históricas, de acción, y de gestión de estas luchas colectivas en torno al derecho de vivienda y de la ciudad en Madrid mediante el contraste entre ambas. Por un lado, las luchas vecinales que se sucedieron en los 70 y 80 del siglo pasado en Madrid derivaron de la necesidad de mejora de sus viviendas e infraestructuras (luz, agua, transporte, asfaltado, alcantarillado, etc.), por parte de una sociedad que migraba hacia las grandes urbes. Y por otro, el momento actual, de especulación voraz de las vivienda, en una crisis de accesibilidad de gran parte de la población para poder adquirir una vivienda por el encarecimiento de éstas, que acabó movilizando en 2006 a un sector de la población en las distintas sentadas que se sucedieron en las principales ciudades de Espa a, reclamando el derecho a una vivienda digna.
The Tomaraho Conception of the Sky
Guillermo Sequera,Alejandro Gangui
Physics , 2011,
Abstract: The small community of the Tomaraho, an ethnic group culturally derived from the Zamucos, became known in the South American and world anthropological scenario in recent times. This group, far from the banks of the Paraguay river, remained concealed from organized modern societies for many years. Like any other groups of people in close contact with nature, the Tomaraho developed a profound and rich world view which parallels other more widely researched aboriginal cultures as well as showing distinctive features of their own. This is also apparent in their imagery of the sky and of the characters that are closely connected with the celestial sphere. This paper is based on the lengthy anthropological studies of G. Sequera. We have recently undertaken a project to carry out a detailed analysis of the different astronomical elements present in the imagined sky of the Tomaraho and other Chamacoco ethnic groups. We will briefly review some aspects of this aboriginal culture: places where they live, regions of influence in the past, their linguistic family, their living habits and how the advancement of civilization affected their culture and survival. We will later mention the fieldwork carried out for decades and some of the existing studies and publications. We will also make a brief description of the methodology of this work and special anthropological practices. Last but not least, we will focus on the Tomaraho conception of the sky as well as describe the research work we have been doing in recent times.
The representations of the sky among the Tomaraho
Guillermo Sequera,Alejandro Gangui
Physics , 2014,
Abstract: The Tom\'ar\~aho is an ethnic group of the Paraguayan Chaco who maintained close contact with nature and developed original ways of explaining and understanding it. This article presents the first results of an interdisciplinary project seeking to provide a detailed analysis of different astronomical elements in the imagined sky of the Tom\'ar\~aho.
Fósforo, calcio y azufre disponibles de la roca fosfórica acidulada con ácido sulfúrico y tiosulfato de amonio
Sequera,Omaira; Ramírez,Ricardo;
Interciencia , 2003,
Abstract: n, p, ca and possibly s are critical in maize and sorghum production in acidic soils. the use of phosphate rock (rf) acidulated with sulfuric acid (as) as source of these elements in short term crops is possible. the use of ammonium thiosulfate (tsa) for rf acidulation combined with sulfuric acid (sa) is feasible. an acidic soil low in p and ca was used to test the efficiency of rf acidulated with sa and tsa. field and incubation experiments were conducted on limed (se) and non-limed soil (sse). fertilizer treatments were: rf acidulated with as (ra), rf acidulated with 70% as and 30% tsa, (r30t); rf acidulated with tsa (r100t), triple super-phosphate (sp) and 0p. the p dosis applied to the soil was 400mg·kg-1. released p in sse with ra and r30t was higher than with rf and r100t, but p released from r30t in se was lower than that from ra in the first 21 days. in sse there were no differences in maize dry matter (ms) where sft, ra or r30t were used, but ms was higher than where rf or r100t were applied. in se there were no ms differences between r30t, rf and r100t. in sse maize p uptake was higher when ra and r30t were used but in se, p uptake was higher in r30t. a significant negative relationship was found between root length and p uptake in se, while in sse they were not related. partial acidulation of rf, substituting 30% as by tsa, does not change the efficiency of rf as a p source.
Page 1 /15825
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.