748 research outputs found
Experimental evaluation of Supervised Reciprocal Filter Strategies for OFDM-radar signal processing
No full textIn this paper, we present an experimental evaluation of recently proposed Supervised Reciprocal Filter approaches for the compression of OFDM-radar signals. The range-Doppler map is usually evaluated using a suboptimal batches algorithm, after fragmenting the signal in batches with length equal to the OFDM symbol. Using "OFDM fragmentation" requires symbol synchronization and sets constraints on the non-ambiguous Range-Doppler area of targets that can be detected with limited Signal-to-Noise Ratio (SNR) loss. Supervised Reciprocal Filters have been recently proposed to operate with batches of longer lengths than the OFDM symbol without requiring any synchronization. In this paper we extend the study to include the case of batches equal to a fraction of the OFDM symbol, which provides higher flexibility to adapt the processor to the range-Doppler scenario of interest. These filters have been shown to contain the large SNR losses obtained with a direct application of the Reciprocal Filter (RF) with the non-OFDM fragmentation. Moreover, they have been shown theoretically to preserve the benefits of the RF over the Matched Filter (MF) against the clutter-limited scenarios. To assess the performance of the Supervised Filter against a real scenario, an acquisition campaign has been carried out using the Sapienza experimental passive radar along the coast north of Rome, against a maritime traffic scenario, including non-cooperative vessels, as well as a cooperating small boat equipped with differential GPS positioning registration tools. The effectiveness of the proposed approaches is validated by applying them to experimental data from a PBR application exploiting DVB-T transmissions
Loaded reciprocal filter for OFDM-based passive radar signal processing
No full textThe Range-Doppler maps of Passive Bistatic Radar (PBR) are often evaluated by means of the suboptimal batches algorithm. For OFDM waveforms of opportunity, a typical choice is to fragment the signal in batches length equal to the OFDM symbol length. This is shown to provide Signal-to-Noise Ratio (SNR) losses for both Matched Filter (MF) and Reciprocal Filter (RF), especially for long target ranges. We investigate the case of “non-OFDM fragmentation”, with special attention to the case of batch length much longer than a single OFDM symbol that can potentially reduce the losses at long ranges. While this is effective for the MF, we show that the RF filter in this case still provides high Peak-to-Sidelobes Ratio (PSLR) values but at the expense of significant SNR losses. Therefore, we propose the Loaded Reciprocal Filter (LRF) as a modified version of the RF for the non-OFDM fragmentation case, which is shown to provide a trade-off between SNR losses and PSLR. Finally, a simulated case study is presented for a DVB-T-based PBR, which clearly shows the effectiveness of the proposed LRF scheme when using the non-OFDM fragmentation
Performance prediction of the loaded reciprocal filter for OFDM-based passive radar
No full textThe Range-Doppler maps of Passive Bistatic Radar (PBR) are often evaluated by means of the suboptimal batches algorithm. For OFDM waveforms of opportunity, the Reciprocal Filter (RF) is often used to perform range compression at each batch since it provides a high Peak-to-Sidelobe Ratio (PSLR) while suffering from relatively low Signal-to-Noise Ratio (SNR) losses when the signal is fragmented in batches equal to the OFDM symbols. In some applications, this fragmentation leads to a performance degradation and an unconstrained batching strategy should be use. For this fragmentations, the RF keeps a high PSLR but yields significant SNR losses. To solve this issue, the Loaded Reciprocal Filter (LRF) has been proposed as an empirical modified RF version that provides a trade-off between SNR losses and PSLR. In this paper, we extend our previous results and provide a theoretical analysis of the performance of the LRF
Javier Heraud, El Río
No full textThe present teaching proficiency piece of work has been done to get the license to practice as a Spanish Language and Literature teacher. The learning session has been designed for the fifth year secondary students of Antonio Torres Araujo school and it was held on the 5th of December, 2019. It is entitled “Javier Heraud, el río” (Javier Heraud, the river) and it is made up of three parts which are related to each other around the most meaningful Heraud´s poem called “El río” (The river). The learning session design describes the specific learning skills that fifth year secondary students must develop as well as the activities that have been planned according to their age which will let us observe students’ performance in class. The pedagogical support involves the methodology, didactics and evaluation which are essential for the learning session to be developed so as the students can be adapted to the new knowledge. The theoretical support considers the concepts and theories regarding the new knowledge, that is to say, Javier Heraud’s poetry which belongs to the Spanish Language and Literature area.El presente trabajo de suficiencia profesional para optar por el título profesional de Licenciado en Educación con mención en Lengua y Literatura; se llevó acabo en la Institución Educativa, Antonio Torres Araujo, el día cinco de diciembre del 2019, y fue elaborada para los estudiantes del quinto año. La sesión de aprendizaje lleva por título, ¨Javier Heraud, el río¨ y está estructurada en tres partes, las cuales tienen relación entre sí, cuyo eje temático es el tema de la obra de Heraud, “El río”, su poema más significativo. En el diseño de la sesión de aprendizaje, se describen las competencias y capacidades específicas que deben desarrollar los estudiantes del quinto año, así como las actividades que han sido planificadas de acuerdo a su edad, y que permitirán observar claramente sus desempeños durante la clase. El sustento pedagógico, contempla la metodología, didáctica y evaluación, aspectos fundamentales para el desarrollo de esta sesión de aprendizaje y para que los estudiantes puedan adaptarse al nuevo conocimiento. El sustento teórico, consta de los conceptos y teorías que involucra el desarrollo de un conocimiento nuevo correspondiente al área de Lengua y Literatura como es la poesía de Javier Heraud.Trabajo de suficiencia profesiona
A fast disturbance cancellation scheme for orthogonal frequency division multiplexing‐based passive radar exploiting reciprocal filter
No full textThis paper proposes a simple non‐adaptive approach for the suppression of direct signal and clutter contributions in a passive radar system based on orthogonal frequency division multiplexing transmissions, exploiting the properties of a reciprocal filter (RF). The use of a RF allows to circumvent the limits posed by the waveform ambiguity function, producing a data‐independent time‐invariant response to a stationary point‐like target echo at the output of the range compression stage. This feature enables simple clutter cancellation strategies, based on the subtraction of delayed portions of the surveillance signal, according to the conventional moving target indication methodologies. The proposed processing scheme consists of a range compression stage based on a RF, followed by a Single Canceller. Its performance is investigated against a simulated and an experimental data set, for the case of a digital video broadcasting‐terrestial‐based passive radar scenario, and it is compared to an alternative scheme based on a conventional matched filter and adaptive cancellation techniques. The proposed approach is shown to yield a perfect cancellation of the clutter returns from a stationary scene under ideal conditions. Moreover, it proves to be robust to real‐world conditions, despite its considerably limited computational load compared to adaptive clutter cancellation techniques
Exploiting the properties of reciprocal filter in low-complexity OFDM radar signal processing architectures
No full textThis paper explores signal processing architectures for disturbance cancellation and range-Doppler map evaluation in Orthogonal Frequency Division Multiplexing (OFDM) radar. The signal processing chain of an OFDM radar typically encompasses a disturbance cancellation stage followed by the range-Doppler map evaluation, which can be in turn decomposed into a range compression stage performed at OFDM symbol level and a Doppler processing across symbols. In this work we use a Reciprocal Filter (RF) to perform the range compression and we deepen the understanding of the RF properties with particular reference to their impact on the other processing stages of the signal processing scheme, above all disturbance cancellation. By exploiting this understanding, we show that it is possible to create synergies between different processing stages, even swapping their order, with the aim to improve the performance of the system while keeping limited its complexity. Thanks to this strategy, alternative versions of existing disturbance cancellation algorithms can be considered that would not be feasible in conventional architectures. Moreover, this study makes it possible to include within the same interpretative framework approaches that seem to be very distant from each other in terms of processing techniques thus allowing their throughout comparison both in terms of target detection performance and in terms of computational complexity. The performance of different solutions is investigated and compared against simulated and experimental data for the case of a OFDM radar that parasitically exploits DVB-T signals of opportunity
Recommended from our members
Mr Secrets and Social Media: the Confession of Richard Rodriguez
No full textRichard Rodriguez's works create troubling situations for many scholars. Though numerous critics see him as the penultimate Chicano writer, many others see his writing as only pandering to the elite. However, all politics and controversies aside, he is a writer whose ideas upon language and public confession have been revolutionary. Throughout the thesis, I argue that Rodriguez's ideas upon language and identity are applicable to the social media landscape that we reside in currently, especially the public confession. Also, I use deconstructionism, along with postmodern criticism, to illustrate the changing arc of Rodriguez's confession from his first autobiography to his final one. In his first memoir, Rodriguez remains in the closet upon his sexuality, and the reader only catches glimpses of the 'real' character inside his work. In the second memoir, the reader sees a better glimpse because of his coming out; yet, even in this regard, he does not do so wholly and still leaves his confession unfinished. By the third, he applies themes and problems seen in his first and second works to discuss our browning nature, and how we are all sinners and that we desire to confess our sins. In my assessment of Rodriguez, I argue throughout all my chapters upon a measure of irreconcilability between the private world of the Hispanic immigrant family and the public sphere that they are forced to inhabit because of his citizenship and education. This irreconcilability creates a drastic limiting of identity for the author that Rodriguez is forced to navigate which creates his desire for confession
Nivel de satisfacción de los alumnos de pregrado de ciencias clínicas de la facultad de medicina con el aula virtual en el contexto de la pandemia por COVID-19. Universidad Nacional de Trujillo
No full textTo determine the satisfaction of undergraduate students of clinical sciences with the use of the virtual classroom in the context of the COVID-19 pandemic.
Material and method: A descriptive, cross-sectional observational study was carried out applying a survey to 180 clinical science medicine students collecting information on general characteristics of virtual education and using a Likert-type scale, the level of the virtual classroom and student satisfaction were measured.
Results: 79.44% of the participants showed a frequency of use of more than 5 days a week (very frequent). Likewise, the videoconferencing tools and tasks that were most used were google meet and zoom (56.67%). On the other hand, only 5.56% of the participants reported not using support tools in addition to their taught classes. The characteristics that were associated with student satisfaction were gender (p = 0.015), the level of the year of studies (p=0.004) and the level of the virtual classroom (p <0.001). However, those that were not associated were the use of videoconferencing tools and homework (p=0.308) and support (p=0.819).
Conclusions: Undergraduate students of clinical sciences used the virtual classroom of the National University of Trujillo very frequently and are moderately satisfied. This experience entails continuous improvement to reinforce some identified weaknesses.Determinar la satisfacción de los alumnos de pregrado de ciencias clínicas con el uso del aula virtual en el contexto de pandemia del COVID-19.
Material y método: Se realizó un estudio observacional descriptivo de corte transversal aplicando una encuesta a 180 alumnos de medicina de ciencias clínicas recolectando información sobre características generales de la educación virtual y mediante una escala tipo Likert se midió el nivel del aula virtual y la satisfacción del estudiante.
Resultados: El 79,44% de los participantes mostraron una frecuencia de uso de más de 5 días a la semana (muy frecuente). Asimismo, las herramientas de videoconferencia y tareas que más se utilizaron fueron google meet y zoom (56,67%). Por otro lado, solo el 5,56% de los participantes reportaron no usar herramientas de apoyo adicionalmente a sus clases impartidas. Las características que estuvieron asociadas a la satisfacción estudiantil fueron el sexo (p=0,015), el nivel del año de estudios (p=0,004) y el nivel del aula virtual (p<0,001). Sin embargo, las que no estuvieron asociadas fueron el uso de herramientas de videoconferencia y tareas (p=0,308) y las de apoyo (p=0,819).
Conclusiones: Los alumnos de pregrado de ciencias clínicas usaron muy frecuentemente el aula virtual de la Universidad Nacional de Trujillo y se encuentran medianamente satisfechos. Esta experiencia conlleva una continua mejora para reforzar algunas debilidades identificadas.Tesi
Processes, information, and accounting gaps in the regulation of Argentina's private railways
No full textAlmost a decade after Argentina began privatizing its railways, resolution of conflicts between regulators, users, and operators continues to take longer, and to be more difficult, than expected. The authors contend that many of these conflicts arose because there are no rules for interactions between the key stakeholders: government, regulators, users, unions, and the media. One result of inexperience in setting up concession agreement has been that the agreements did not clearly define the information needed for oversight and regulation. Argentine rail concession contracts were supposed to be specific about the way tariffs, quality, investment, exclusivity, and so on, would change over time. And the newly created regulatory bodies were given some discretion about adjusting the contracts in the face of unforeseen developments. However, initial privatization were carried out in such a way that there was no time to refine terms, so many loopholes remained. Those unforeseen events have happened, and the regulatory agency, the National Commission for Transport Regulation (CNRT), has had to adapt its procedures and decisions to available information. In some cases, alleged modifications of the operating environment have led to renegotiations. Changes have been introduced in the approach to furnishing information to the government for oversight and regulatory accounting. The changes center on clearer definitions in connection with four major issues: a) The measurement of efficiency; b) access prices; and c) the financial model. Circumstances in the Argentine rail industry early in 2001 did not favor dramatic changes, but current renegotiations could be used to adjust information requirements to reflect what has been learned through six yearsof experience.Environmental Economics&Policies,Knowledge Economy,Labor Policies,Decentralization,Financial Intermediation,Environmental Economics&Policies,Financial Intermediation,Banks&Banking Reform,Education for the Knowledge Economy,Knowledge Economy
Incidencia de la gestión comercial en la rentabilidad de una empresa del rubro de pastelería, Trujillo, período 2022 – 2023
No full textEn esta tesis denominada Incidencia de la gestión comercial en la rentabilidad de una
empresa del rubro de pastelería, Trujillo, período 2022 – 2023; se desarrolló con la
ODS Nº8 Trabajo Decente y Crecimiento Económico; por otro lado, el objetivo
principal fue determinar si existe relación entre la gestión comercial y la rentabilidad
de la empresa pastelera, Trujillo, período 2022 - 2023. Asimismo, como objetivos
específicos se tiene; analizar el ratio de gestión comercial de la empresa pastelera,
Trujillo, período 2022 - 2023; y analizar el ratio de rentabilidad de la empresa
pastelera, Trujillo, período 2022 – 2023; el tipo de investigación fue aplicada, enfoque
cuantitativo, técnica análisis de información documental y la población fueron los
Estados Financieros de la empresa; en los resultados se mostró que existe una
influencia negativa del manejo de la gestión comercial en su rentabilidad, por ende se
concluyó que, la empresa no tomo las mejores decisiones, tanto en la implementación
de estrategias de mejora como en su desempeño
- …
