19 research outputs found
Generación de ruido impulsivo para líneas de energía eléctrica “in door”
No full textEl ruido impulsivo es una de las interferencias más dañinas a las comunicaciones por líneas de energía eléctrica en el interior de edificaciones. Se han reportado en la literatura especializada en el tema, algunos modelos matemáticos de este tipo de ruido, basados en el comportamiento estadístico del ruido. En este trabajo de tesis se estudian varios de estos modelos y se profundiza en uno de ellos, implementando
sobre esa base, un generador de ruido impulsivo a escala de simulación. Este generador que se ha implementado utilizando la plataforma de programación Matlab, el cual se describe en la tesis. Se presenta un análisis detallado de cada uno de los elementos que lo componen, tanto desde el punto de vista del modelo matemático como de su implementación. Finalmente se muestran algunos resultados obtenidos con el mismo, que incluyen una comparación con el ruido impulsivo medido en una institución hospitalaria durante la conexión y desconexión de equipos médicos. En la Introducción se plantea el diseño de la investigación, el problema científico, la hipótesis, los objetivos del trabajo, tareas y resultados esperados. En el capítulo 1 se esclarece el problema científico, para ello se realiza un análisis bibliográfico sobre las comunicaciones PLC. En el capítulo 2 se presentan los modelos reportados en la bibliografía para generar ruido impulsivo en PLC y se detalla el propuesto por Chaouche en (Chaouche, Gauthier, Zeddam,
Tlich, & Machmoum, 2011). En el capítulo 3 se desarrolla la implementación en Matlab del modelo de Chaouche, y se presentan los resultados, En las Conclusiones y Recomendaciones se exponen las conclusiones de la investigación realizada, y los aspectos no resueltos en los que el autor recomienda seguir investigando.Impulsive noise is one of the most harmful interference to communications by electric power lines inside buildings. Some mathematical models of this type of noise, based on the statistical behavior of noise, have been reported in the literature specialized in the subject. In this thesis work, several of these models are studied and one of them is deepened, implementing on that basis, an impulsive noise generator at a simulation scale. This generator has been implemented using the Matlab programming platform, which is described in the thesis. A detailed analysis of each of the elements that compose it is presented, both from the point of view of the mathematical model and its implementation. Finally some results obtained with
it are shown, which include a comparison with impulsive noise measured in a hospital institution during the connection and disconnection of medical equipment. In the Introduction the design of the research, the scientific problem, the hypothesis, the objectives of the work, tasks and expected results are presented. In chapter 1, the scientific problem is clarified, for which a bibliographic analysis on PLC communications is carried out. Chapter 2 presents the models reported in the literature to generate impulse noise in PLC and details the one proposed by Chaouche in (Chaouche, Gauthier, Zeddam, Tlich, & Machmoum, 2011). In
Chapter 3, the Matlab implementation of the Chaouche model is developed, and the results are presented. The Conclusions and Recommendations present the conclusions of the research carried out, and the unresolved aspects in which the author recommends further research
High Gain Circularly Polarized Antenna Loaded With Dual-Band AMC structure for WBAN Applications
No full textOptimization of dual-band notched UWB Trapezoidal Antenna using Genetic Algorithm Approach
No full textA Dual-Band Antenna Backed by AMC Surface Using Genetic Algorithm for 2.4/5.8 GHz Underground Mining Communications
No full textCompact coplanar waveguide‐fed reconfigurable fractal antenna for switchable multiband systems
No full textIn this study, a coplanar waveguide-fed reconfigurable antenna using crescent-shaped fractal geometry is presented. The frequency reconfigurable approach is obtained using radio-frequency positive intrinsic negative diodes, resistor, and inductors. The proposed approach has successfully allowed reconfigurable switching up to eight frequency bands between 1.46 and 6.15 GHz. Good results have been obtained in terms of stable and omnidirectional radiation patterns. The realised gains of the antenna system, in these frequency bands, vary from 0.52 to 5.67 dBi. The designed antenna has the advantages of a multiband structure and compact size over the previously reported structures. The proposed antenna is suitable for future wireless application systems
A Wearable Circularly Polarized Antenna Backed by AMC Reflector for WBAN Communications
No full textA new flexible circularly polarized (CP) wearable antenna is proposed for Wireless BodyArea Network systems (WBAN) operating at 5.8 GHz. The circular polarization is enabled by combining a microstrip-line monopole feed and an inverted L-shaped conformal metal strip extended from a coplanar waveguide. The proposed antenna shows satisfactory performance in terms of gain and specific absorption rate (SAR) at a separation of 12 mm from a human body model. To minimize body-antenna separation, a flexible 2 × 2 artificial magnetic conductor (AMC) was used as a reflector to achieve good performances in terms of gain and SAR. The total footprint of the proposed antenna is only 34.4 × 34.4 mm2(0.384 λ20) board of semi-flexible Rogers RT-Duroid 5880 substrate. The final design provides a peak gain of 7.6 dBi and an efficiency of 94.7% when worn on the body. Furthermore, evaluation results indicate that the maximum SAR level decreased by up to 20.42% in comparison with the CP antenna without the AMC. Full-wave EM simulation and experimental results are performed, both in free space and proximity to the human body under different bending scenarios. Overall, the proposed antenna performance has been shown to be robust to structural deformation along the x-axis in comparison to previously reported designs. These features demonstrate that the proposed antenna is a strong candidate for off-body wearable applications
Cerebellar liponeurocytoma: Rare posterior fossa tumor
No full textCerebellar liponeurocytoma is a rare WHO grade II glioneuronal tumor, characterized by a benign course and a more favorable prognosis. In this paper, we report a 52-year-old man, hospitalized in emergency because of clinical signs of increased intracranial pressure, and gait disturbances. The MRI revealed a lateral well shaped solid lesion within the left cerebellar hemisphere, having a low signal intensity compared to the cerebrospinal fluid, and causing a triventicular hydrocephalus and tonsillar herniation. The patient underwent a direct approach of the tumor through a left suboccipital craniectomy. Total removal of the lesion was achieved, and the histological diagnosis was cerebellar liponeurocytoma. The tumor cell proliferation index was < 6 %, therefore, radiotherapy and chemotherapy were not implemented after surgery. After 5 years of close follow-up there were no clinical or radiological signs of recurrence.Our objective in reporting another case of this unusual tumor is to discuss clinical profile, radiologic and histologic features as well as treatment and prognosis of this rare posterior fossa tumor
Ileal intussusception secondary to lipoma in an adult patient: A rare cause for intestinal obstruction: A case report
No full textIntussusception is a rare condition in adults, unlike in children, with a variety of etiologies. In most cases, it is secondary to tumors. acute intussusception on lipoma is very exceptional. We report a case of 68-year-old female patient, diagnosed with intestinal intussusception on lipoma
Wandering spleen torsion with splenic vein thrombosis: A case report
No full textWandering spleen is a rare condition characterized by the absence or underdevelopment of one or all of the ligaments that hold the spleen in its normal position in the left upper quadrant of the abdomen. It is an uncommon clinical entity that mainly affects children. Among adults, it most frequently affects women of reproductive age, in whom acquired laxity of the splenic ligaments is usually the cause. Patients with a wandering spleen may be asymptomatic, or may present with a movable mass in the abdomen. They can have chronic or intermittent abdominal pain because of partial torsion and spontaneous detorsion of the spleen. Given the nonspecific clinical symptoms and the potential complications associated with a wandering spleen, computed tomography provides crucial means for proper diagnosis. In this article, we report the case of a 17-year-old female patient presenting with a wandering spleen torsion and spleen vein thrombosis
Pelvic cellulitis, a rare complication of bartholinitis: report of two cases
No full textPelvic or pelviperineal cellulitis is a rare but serious complication of bartholinitis and can be life-threatening. It is described of polymicrobial nature. The diagnosis of pelvic cellulitis remains essentially clinical with signs of local inflammation.The interest of imaging, CT in particular, is to assess the extent of the infection and abcess.In this report, we describe 2 cases of pelvic cellulitis complicating a bartholin's abscess caused by negative gram bacilli in 2 diabetic women in their sixties
