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Search Results: 1 - 10 of 3628 matches for " Dario Marin "
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Symmetric Solutions of a Nonlinear Elliptic Problem with Neumann Boundary Condition  [PDF]
Ana Magnolia Marin Ramirez, Ruben Dario Ortiz Ortiz, Joel Arturo Rodriguez Ceballos
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.311233
Abstract: We show a result of symmetry for a big class of problems with condition of Neumann on the boundary in the case one dimensional. We use the method of reflection of Alexandrov and we show one application of this method and the maximum principle for elliptic operators in problems with conditions of Neumann. Some results of symmetry for elliptic problems with condition of Neumann on the boundary may be extended to elliptic operators more general than the Laplacian.
Web-Based Specialist Support for Spinal Cord Injury Person’s Care: Lessons Learned
Vincenzo Della Mea,Dario Marin,Claudio Rosin,Agostino Zampa
International Journal of Telemedicine and Applications , 2012, DOI: 10.1155/2012/861860
Abstract: Persons with disability from spinal cord injury (SCI) are subject to high risk of pathological events and need a regular followup even after discharge from the rehabilitation hospital. To help in followup, we developed a web portal for providing online specialist as well as GP support to SCI persons. After a feasibility study with 13 subjects, the portal has been introduced in the regional healthcare network in order to make it compliant with current legal regulations on data protection, including smartcard authentication. Although a number of training courses have been made to introduce SCI persons to portal use (up to 50 users), the number of accesses remained very low. Reasons for that have been investigated by means of a questionnaire submitted to the initial feasibility study subjects and included the still easier use of telephone versus our web-based smartcard-authenticated portal, in particular, because online communications are still perceived as an unusual way of interacting with the doctor. To summarize, the overall project has been appreciated by the users, but when it is time to ask for help to, the specialist, it is still much easier to make a phone call. 1. Introduction Persons with disability from spinal cord injury (SCI) are subject to high risk of pathological events and need a regular followup even after discharge from the rehabilitation hospital [1]. SCI causes sensory, motor, and autonomic impairments, but often in long-term also a variety of secondary conditions on different domains, for example, physical (bladder and bowel problems, pain, spasms, pressure sores, and sexuality), psychological (anxiety and depression), and social (transport, finance, equipment, housing, care management, and employment). SCI is not a static condition, but rather a process of continuous adaptation due to interactions with the aging process. Advanced age has been associated with increases in a number of secondary health complications including bowel complications, cardiovascular and respiratory complications, pressure ulcers, urinary tract infections, renal stones, and musculoskeletal pain. Like in other countries, also in the Italian health-care system the GP is the first contact point for the person in need of health care. The same is true for people with SCI, encouraged to contact first their GP for health problems, but the limited expertise on SCI of the GP was seen by persons with an SCI as the greatest barrier to needs being met [1]. Thus most of SCI persons turn to either specialists of spinal units or rehabilitation centers, whose intervention
The Harper-Hofstadter Hamiltonian and conical diffraction in photonic lattices with grating assisted tunneling
Tena Dub?ek,Karlo Lelas,Dario Juki?,Robert Pezer,Marin Solja?i?,Hrvoje Buljan
Physics , 2015,
Abstract: We introduce a grating assisted tunneling scheme for tunable synthetic magnetic fields in photonic lattices, which can be implemented at optical frequencies in optically induced one- and two-dimensional dielectric photonic lattices. We demonstrate a conical diffraction pattern in particular realization of these lattices which possess Dirac points in $k$-space, as a signature of the synthetic magnetic fields. The two-dimensional photonic lattice with grating assisted tunneling constitutes the realization of the Harper-Hofstadter Hamiltonian.
Diophantine Equations and the Freeness of Möbius Groups  [PDF]
Marin Gutan
Applied Mathematics (AM) , 2014, DOI: 10.4236/am.2014.510132
Abstract: Let p and q be two fixed non zero integers verifying the condition gcd(p,q) = 1. We check solutions in non zero integers a1,b1,a2,b2 and a3 for the following Diophantine equations: (B1) \"\" (B2) \"\".
The equations (B1) and (B2) were considered by R.C. Lyndon and J.L. Ullman in [1] and A.F. Beardon in [2] in connection with the freeness of the M?bius group \"\" generated by two matrices of \"\" namely \"\" and \"\" where \"\". They proved that if one of the equations (B1) or (B2) has solutions in non zero integers then the group \"\" is not free. We give algorithms to decide if these equations admit solutions. We obtain an arithmetical criteria on p and q for which (B1) admits solutions. We show that for all p and q the equations (B1) and (B2) have only a finite number of solutions.
Weak Solutions in Elasticity of Dipolar Porous Materials
Marin Marin
Mathematical Problems in Engineering , 2008, DOI: 10.1155/2008/158908
Abstract: The main aim of our study is to use some general results from the general theory of elliptic equations in order to obtain some qualitative results in a concrete and very applicative situation. In fact, we will prove the existence and uniqueness of the generalized solutions for the boundary value problems in elasticity of initially stressed bodies with voids (porous materials).
On the Nonlinear Theory of Micropolar Bodies with Voids
Marin Marin
Journal of Applied Mathematics , 2007, DOI: 10.1155/2007/15745
Abstract: This paper is concerned with the nonlinear theory of micropolar, porous, and elastic solids. By using the theory of Langenbach, within this context, we obtain some existence and uniqueness results.
Simulated Sample Behaviour of a Dissimilarity Index When Sampling from Populations Differing by a Location Parameter Only  [PDF]
Fabio Manca, Claudia Marin
Applied Mathematics (AM) , 2014, DOI: 10.4236/am.2014.515213
Abstract: In this paper the authors study empirically the power of the test based on the index of dissimilarity to compare two samples drawn from two populations differing only in the location parameter. We call such a test as test of homogeneity. In practice the power of such a bidirectional test will be studied referring to the absolute value of the shiftδand to the same probability models considered by Fried and Dehling.
Educating towards Musical Historical Heritage: What Difficulties?  [PDF]
Elita Maule, Dario De Cicco
Creative Education (CE) , 2012, DOI: 10.4236/ce.2012.326163
Abstract: How does one set about helping children and teenagers to understand the different musical styles and genres, the historical context pertaining to works of music and composers, or the historical aesthetic appreciation of the musical repertoire? Are these aims achievable and simple to attain with students? This article intends to focus on this very aspect, deemed important and included in all the national curricula throughout Europe. It will show that the teacher’s familiarity with the specialist musical code could lead him/her to take for granted technical knowledge that the student does not actually possess and that the problems of temporal conceptualization should represent an object of careful reflection for all teachers.
Distortionless Lossy Transmission Lines Terminated by in Series Connected RCL-Loads  [PDF]
Vasil G. Angelov, Marin Hristov
Circuits and Systems (CS) , 2011, DOI: 10.4236/cs.2011.24042
Abstract: The paper deals with a lossy transmission line terminated at both ends by non-linear RCL elements. The mixed problem for the hyperbolic system, describing the transmission line, to an initial value problem for a neutral equation is reduced. Sufficient conditions for the existence and uniqueness of periodic regimes are formulated. The proof is based on the finding out of suitable operator whose fixed point is a periodic solution of the neutral equation. The method has a good rate of convergence of the successive approximations even for high frequencies.
Approaches to Low Fuel Regression Rate in Hybrid Rocket Engines
Dario Pastrone
International Journal of Aerospace Engineering , 2012, DOI: 10.1155/2012/649753
Abstract: Hybrid rocket engines are promising propulsion systems which present appealing features such as safety, low cost, and environmental friendliness. On the other hand, certain issues hamper the development hoped for. The present paper discusses approaches addressing improvements to one of the most important among these issues: low fuel regression rate. To highlight the consequence of such an issue and to better understand the concepts proposed, fundamentals are summarized. Two approaches are presented (multiport grain and high mixture ratio) which aim at reducing negative effects without enhancing regression rate. Furthermore, fuel material changes and nonconventional geometries of grain and/or injector are presented as methods to increase fuel regression rate. Although most of these approaches are still at the laboratory or concept scale, many of them are promising. 1. Introduction Hybrid rocket engines (HREs) are chemical rockets which present interesting advantages over liquid rocket engines (LREs) and solid rocket motors (SRMs) and can provide a safe and affordable option for many applications. They have recently come to the fore as they have been chosen to power the second stage of the Tier One, the winner of the $10 million X-Prize [1]. The Tier One (http://www.scaled.com/projects/tierone/) was the first privately-developed reusable vehicle able to perform a manned suborbital flight over 100?km. The first stage of the Tier One is a twin-turbojet carrier-launch aircraft, called the White Knight, which is able to bring the second stage to 15?km altitude. The second stage, the SpaceShipOne, is a reusable three-place manned space plane, powered by an N2O/HTPB hybrid rocket engine. This HRE has a burning time of about 80 seconds and it is able to produce an average thrust of 75?kN with a vacuum specific impulse of about 250?s. The Tier One was retired after winning the X-Prize, but it remains proof that HREs may be the key propulsion system of the emerging space market [2]. In HREs, oxidizer and fuel are separated and stored in two different physical phases. In the most common configuration, a liquid or gaseous oxidizer and a solid-fuel grain are employed (direct HRE). In the conventional configuration the grain is cylindrical with a circular port. Due to this propellant storage, HREs have a peculiar combustion process as shown Figure 1. A boundary layer is formed when the oxidizer is injected into the port of the fuel grain. After ignition a diffusion flame is formed inside this layer. The fuel deriving from the solid grain is gasified by the heat coming
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