Ademir Xavier

Ademir Xavier
Brazilian Space Agency · DIEN

PhD in Physics

About

74
Publications
39,929
Reads
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324
Citations
Additional affiliations
July 2016 - present
Brazilian Space Agency
Position
  • Physicist & Technologist 3-III
February 2015 - present
Centro de Tecnologia da Informação Renato Archer
Position
  • Project Manager
February 2002 - February 2015
Centro de pesquisas Avançadas
Position
  • Senior Researcher
Description
  • See: http://www.vonbraunlabs.com/
Education
January 1994 - September 1996
University of Campinas
Field of study
  • Physics
February 1988 - January 1992
University of Campinas
Field of study
  • Physics

Publications

Publications (74)
Preprint
Full-text available
Using classical electrodynamics, this work analyzes the dynamics of a closed microwave cavity as a function of its center of energy. Starting from the principle of momentum conservation, expressions for the maximum electromagnetic momentum stored in a free microwave cavity are obtained. Next, it is shown that, for coherent fields and special shape...
Article
Full-text available
Automatic and innovative equipment was developed to inspect the assembly of pin-through-hole components on printed circuit boards. Its performance was tested on an industrial assembly line of motherboards for desktop computers. The test was conducted to inspect, under the binomial criterion Pass/Fail, the process of inserting PTH-DIMM components on...
Preprint
Full-text available
This work considers the cospectral and arbitrary light emission of a moving source. The observed wavelengths of the emitted photons are described in term of kinematic and dynamical Doppler shifts in which the mass-energy relation plays a fundamental role. The presentation is an alternative way of emphasizing the importance of the concept of proper...
Preprint
This note applies the Logistic model approximation to determine the suitable start and end dates for the observed epidemic curves in the total number of cases for different countries. The Logistic model is presented and explicit relations for the beginning and end dates are obtained together with the total epidemic duration. Using data from Brazil,...
Article
Full-text available
This paper exposes initially the motivations for developing a TRL online calculator by AEB (Brazilian Space Agency; in Portuguese, Agência Espacial Brasileira). Such motivations demand the tool to be a way not only to assess the TRL condition of operational space missions and systems, but also as a method of evaluating and sharing proposals with ne...
Preprint
Full-text available
This report describes a C++ code to fit the Logistic model to the daily total cases reported by data sources of the COVID-19 outbreak using least-squares. Some examples for China, Brazil, India and Italy are tested numerically and the code listing is given. The method can be used to "track" the daily evolution of new cases and to make predictions a...
Article
Full-text available
O Centro Internacional de Pesquisa do Atlântco (Atlantc Internatonal Research Center - AIR) é uma iniciatva de diversos países banhados pelo oceano Atlântco os quais, sob a liderança e patrocínio do Governo de Portugal, têm o arquipélago dos Açores como sua sede. Voltado para coleta de dados e pesquisas inovadoras, fruto da sinergia mar/espaço, o c...
Preprint
Full-text available
The basic equations to calculate approximate values for the electromagnetic fields around square loop antennas carrying low-frequency oscillating currents are presented. The calculation provides key elements for impedance determination and antenna coverage area (as used, for example, in HF RFID systems). The determination is valid for the (constant...
Conference Paper
Full-text available
A classificação de satélites por massa é uma das principais métricas para definição do porte e dos custos de lançamento desses dispositivos. A existência de muitas classificações, com categorias de tamanho e valores de faixas de massa, torna imprecisa uma caracterização mundial desses dispositivos. Diante disso, foi realizado um estudo bibliográfic...
Preprint
This paper exposes initially the motivations for developing and releasing a TRL online calculator by AEB (Brazilian Space Agency). Such motivations demands the tool to be a way not only to assess the readiness degree of past space missions and systems, but also as a method of evaluating and sharing new proposals with technological content. The TRL...
Article
Full-text available
The classification of spacecraft by mass is one of the main metrics to define the size of launch vehicles and the costs of launching satellites into orbit. The existence of many classifications (based on size categories and mass range values) makes inaccurate their common global characterization. This paper presents a review of the main satellite c...
Poster
Full-text available
A classificação de satélites por massa é uma das principais métricas para definição do porte e dos custos de lançamento desses dispositivos. A existência de muitas classificações, com categorias de tamanho e valores de faixas de massa, torna imprecisa uma caracterização mundial desses dispositivos. Diante disso, foi realizado um estudo bibliográfic...
Preprint
Full-text available
Este trabalho tem como objetivo sugerir medidas bem definidas quantitativamente de deter-minação de risco em situações típicas de investimentos a fim de aprimorar sua cultura de controle de risco. Para isso, aplicam-se medidas de probabilidade já consolidadas estatisticamente, bem como diversos princípios auxiliares, no tratamento de dois exemplos...
Article
Full-text available
In this work, the mechanism behind motion in closed systems is investigated by studying two simple mechanical systems. Firstly, a simple "ballistic" car system introduces the subject of propulsion as a function of a parameter that modulates the amount of ejected mass, thus allowing a transition between a closed to an open system. The second example...
Preprint
Full-text available
In this work, we present a study of numerical solutions for finite cylindrical capacitors based on the integration of Poisson equation using a finite difference scheme. Solutions are obtained by successive over-relaxation (SOR). The problem illustrates the numerical treatment involved in the solution of problems not found in textbooks. Several inte...
Preprint
Full-text available
Study notes summarizing the basics on Support Vector Machines (SVM) for binary classification. Some pseudo-codes are provided as an introduction to SVM programming.
Preprint
Full-text available
High contrast and deep-sky astrophotos require accurate camera tracking for more than 40 seconds of exposure time. For those seeking a homemade solution in astrophotography, a good idea is to build your own camera platform. In this paper, I study and develop the theory behind some tracking systems using the concept of "barn door" or hinge platform...
Preprint
Full-text available
In this work, we present schematic diagrams for the construction of a spectrograph mask attachable to a camera objective in order to capture spectra using simple CD or DVD gratings. A diagram for building a simple spectroscope is also presented as an introduction to the subject. The mask is made of two parts: an adapter ring and elbow-shaped blocka...
Preprint
This paper introduces and describes an innovative automatic equipment to inspect the assembly of Pin Through Hole – PTH components on printed circuit boards (PCBs). This equipment is designed, developed and tested for automatically inspecting the process of inserting PTH components on PCBs. The performance of this equipment was tested on an industr...
Book
Full-text available
A mais completa obra publicada no Brasil sobre estatística voltada para o mercado de ações utilizando o Excel. Da estatística básica até a programação de estratégias automáticas, a obra introduz o leitor ao mundo da automação do investimento de risco. Usando planilhas descritas no texto e disponíveis para download, o leitor é levado a criar as suas...
Preprint
Full-text available
This manuscript presents analytical and numerical calculations of the so-called 'finite aperture approximation' (FAA) for the production of Bessel beams in the microwave region (below 100 GHz). These waves are components of the scalar X-wave (non-dispersive waves). FAA provides the theoretical limit for the creation and propagation of a non-dispers...
Technical Report
Full-text available
Este documento tem como objetivo introduzir e referenciar uma proposta de índice de maturidade tecnológica, em conformidade com requisitos que foram levantados na AEB para missões espaciais. Entende-se que o chamado “TRL – Technology Readiness Level” foi inicialmente concebido para descrição sucinta do nível de maturidade tecnológico de componentes...
Presentation
Full-text available
The riddle of inertia quickly explained as a more fundamental interaction energy of all particles in the universe. Mach’ principle in the pre-relativistic era.
Presentation
Full-text available
Introdução ao processo de adoção de missão espacial.
Poster
Full-text available
O processo de geração automática de interferometria de imagem de radar sintético via software SNAP como plataforma integrada de tratamento de dados SAR do sistema Sentinel-1 é apresentado. Essa ferramenta é ilustrada por uma aplicação de InSar para a região da mina de Germano, em Mariana/MG que demonstra a detecção de subsidência de terreno como ac...
Presentation
Full-text available
My presentation at the first ”Southern Hemisphere Space Technology Application and Education Forum” held in Brasilia, Brazil last August 2017. The presentation describes current efforts of the Brazilian Space Agency toward education and Space.
Article
Full-text available
Neste trabalho, apresentamos diagramas esquemáticos para a construção de uma máscara espectrográfica adaptável à objetiva de uma câmera, a fim de se capturar espectros usando redes feitas de CD ou DVD. A máscara é feita de duas partes: um anel adaptador e um bloqueio em cotovelo para o registro correto de espectro no laboratório ou ao ar livre. Usa...
Presentation
Full-text available
Resumo dos trabalhos apresentados à Agência Espacial Brasileira para criação de sua política de gestão e controle de risco.
Article
Full-text available
We evaluate the groundwater (GW) storage under the state and the city of São Paulo using remote data provided by NASA's Gravity Recovery and Climate Experiment (GRACE) in the context of the water shortage crisis in 2013-2014. The study provides a GW forecasts based on Least Square Support Vector Machine (LS-SVM) for GRACE and Global Land Data Assim...
Presentation
Full-text available
Apresentação sobre os fundamentos da escala TRL (Technology Readiness Level) em sua versão IMATEC ou Índice de Maturidade Tecnológica.
Conference Paper
Full-text available
1. CTI Renato Archer. E-mail:Sergio.celaschi@cti.gov.br 2. Agencia Espacial Brasilreira-AEB. E-mail: ademir.xavier@aeb.gov.br RESUMO Esta proposta de projeto tem como objetivo conceber uma solução abrangente e integrada para a prevenção de colapso nos serviços de telecomunicações em decorrência de desastres naturais ou antrópicos, ou de mitigação d...
Conference Paper
Full-text available
This paper presents a report on the status of a Brazilian network of automatic hydro-meteorological stations. These stations were projected, acquired and installed by the " Centro de Monitoramento e Alerta de Desastres Naturais – CEMADEN " in order to develop and implement a system for monitoring natural disasters. CEMADEN provides early warnings f...
Patent
Full-text available
A RFID tag (500) includes an antenna (100) that includes a first dipole (110), a first feeder portion (130), a second dipole (120) and a second feeder portion (140). The first feeder portion is coupled to the first dipole at two locations a feeder length distance apart. The second feeder portion is coupled to the second dipole at two locations the...
Article
Full-text available
Background Recent national developments in alert systems are the main motivation of this work. The aim is to provide an account on the development and first tests of a new Meteorological Alert System—MAS for mobile devices to deliver alert signals. The fundamentals encompass a summary description of the Brazilian government towards the installation...
Poster
Full-text available
The period between 2013 and 2014 was characterized by a severe drought in the South American southeast, in particular, in the most populated state of Brazil, São Paulo, with the influence of a high-pressure zone at 6000 m above sea level that blocked most of the humid fronts from the Amazon forest (South Atlantic convergence zone, SACZ). The drough...
Conference Paper
Full-text available
A deficiência visual afeta o convívio social dificultando a vida das pessoas. O uso de tecnologias inclusivas pode auxiliar as pessoas portadoras de deficiência visual em algumas atividades do dia-a-dia. Com esse objetivo, o presente trabalho foca no desenvolvimento de instrumentos capazes de ler, em voz sintetizada, textos fotografados em anúncios...
Article
Full-text available
This paper reviews the modeling of stellar images using diffraction theory applied to different types of telescope masks. The masks are projected by secondary mirror holder vanes (such as the spider type) or holes on the primary mirror which result in different configurations of single stellar images. Using Fast Fourier Transform, the image of bina...
Conference Paper
Full-text available
A massive network of rain gauge stations and other hydro-meteorological platforms are being deployed by the CTI/FACTI collaboration through DTR, whose aim is to provide a real time warning system for the population in case of severe climatic anomalies. This network is in fact a subsystem of a wider set of monitoring stations presently commissioned...
Presentation
Full-text available
A brief presentation on numerical methods to "generate" rainfall in order to simulate a network of rain sensors.
Conference Paper
Full-text available
In the context of the Brasil-iD project, this paper proposes a methodology for choosing piezoelectric devices for energy harvesting RFID tags. The proposed methodology guides the search for important device parameters, starting with the capture of their electrical response. By manipulating data, explicit and implicit knowledge of important piezoele...
Article
Full-text available
In this work we present a generalized theory of galvanometers from the point of view of the dynamical equations of coils subjected to general (but homogeneous) time varying magnetic fields. We explore new inductive principles for driving and controlling galvanometers (whose modern versions take the form of scanners) and envisage a special frequency...
Article
Full-text available
We study the dynamics of transverse oscillations near the linear coupling resonance excited by a pair of skew quadrupoles at the LNLS UVX electron storage ring through the analysis of the beam profile. Transverse oscillations were excited with a fast kicker and the resulting oscillating beam profile was observed by focussing visible synchrotron rad...
Article
Full-text available
In this work we present a study of numerical solutions for flnite cylindrical capacitors based on the integration of Poisson equation using a flnite difierence scheme. Solutions are obtained by successive over relaxation (SOR). The problem illustrates the numerical treatment involved in the solution of problems not found in textbooks. Several inter...
Article
Full-text available
This paper shows how to apply a simple Runge-Kutta algorithm to get solutions of Kirchhoff equations for static filaments subjected to arbitrary external and static forces. This is done by suitably integrating at once Kirchhoff and filament reference system equations under appropriate initial boundary conditions. To show the application of the meth...
Article
Full-text available
It is well known that the peak of black body radiation depends on the adopted description, whether as a function of frequency or wavelength. This paper is a pedagogical exposition of how to write and estimate Planck's distribution spectrum on two distinct spectrograph scales. We show that the emitted power of the Black Body maximum is unique and do...
Patent
Full-text available
Utility model patent for an optical inspection tool, capable of automatically detecting failures in SMD component placement on printed circuit boards, based on statistical training using the support vector mchined method for feature separation.
Patent
Full-text available
TITLE Method for extracting quantum information and performing computation in quantum systems using non-distributive lattices implemented on macroscopic automata DESCRIPTION This invention relates to the field of quantum mechanics, how quantum information can be used to perform mathematical calculations and how quantum systems can be represented by...
Book
Full-text available
O mercado de capitais brasileiro está amadurecendo, e conquistamos o grau de investimento. Com o aparecimento de crises financeiras, entretanto, tornou-se claro que a tarefa de todo investidor de sucesso é minimizar, antes de tudo, qualquer chance de perda. Depois disso, seu maior objetivo deve ser fazer crescer o capital. Em tempos de euforia fina...
Article
Full-text available
Isotopic substitution, nuclear reaction analysis, and x-ray photoelectron spectroscopy were employed to show that oxygen-deficient hafnium (Hf) silicates trap hydrogen atoms. Based on this experimental observation, we used first-principles calculations to investigate the structure, energetics, and electronic properties of H interacting with O vacan...
Patent
Full-text available
A self-tuning antenna that automaticll adjusts its input impedance to compensate for externally indeuced impedance variations is provided. A variable impedance is adjusted by a control circuit to reconfigure the input impedance of the antenna to compensate for different environmental situations and different transponder mismatch situations.
Article
Full-text available
Nesse trabalho apresenta-se um estudo de soluções numéricas para o problema de capacitores cilíndricos finitos em eletrostática, a partir da integração da equação de Poisson utilizando um esquema de diferenças finitas. Soluções são obtidas pelo método da relaxação sucessiva. O problema ilustra o tratamento numérico na obtenção de soluções eletrostá...
Article
In this work we present a study of numerical solutions for finite cylindrical capacitors based on the integration of Poisson equation using a finite difference scheme. Solutions are obtained by successive over relaxation (SOR). The problem illustrates the numerical treatment involved in the solution of problems not found in textbooks. Several inter...
Technical Report
Full-text available
Para se tirar boas astrofotografias utilizando câmera móvel sem telescópio (isto é com exposição maior que 40 segundos), é bem conhecida a solução de se utilizar uma motor drive que faz girar um suporte ou " plataforma " sobre a qual se prende a câmera.
Technical Report
Full-text available
Aparentemente, uma imagem tão pequena que não permite revelar muitos detalhes... Mas graças à técnica de análise de imagem, é possível extrair muita informação de uma imagem como essa. Vamos ver como isso é possível. Dessa forma, telescópios e simples webcams podem se tornar instrumentos de medição científica.
Article
Full-text available
A semiclassical formula for the coherent-state propagator requires the determination of specific classical paths inhabiting a complex phase-space and governed by a Hamiltonian flux. Such trajectories are constrained to special boundary conditions which render their determination difficult by common methods. In this paper we present a new method bas...
Article
In this Letter we present a theoretical analysis of an experiment by Mugnai and collaborators where superluminal behavior was observed in the propagation of microwaves. We suggest that what was observed can be well approximated by the motion of a superluminal X wave. Furthermore, the experimental results are also explained by the so called scissor...
Article
In this paper we present thoughtful comments on the paper `Bessel beams and signal propagation' showing that the main claims of that paper are wrong. Moreover, we take the opportunity to show the non trivial and indeed surprising result that a scalar pulse (i.e., a wave train of compact support in the time domain) that is solution of the homogeneou...
Article
Full-text available
A semiclassical formula for the coherent-state propagator requires the determination of specific classical paths inhabiting a complex phase-space through a Hamiltonian flux. Such trajectories are constrained to special boundary conditions which render their determination difficult by common methods. In this paper we present a new method based on Ru...
Preprint
Full-text available
A method for extracting UPOS from a known non-linear dynamical system is described. Examples are worked out numerically for Duffing's oscillator, including the histogram or distribution of UPOs for this oscillator. The list of an F77 algorithm is given for all examples discussed.
Article
Full-text available
We study the dynamics of transverse oscillations near the linear coupling resonance excited by a pair of skew quadrupoles at the Laboratório Nacional de Luz Síncrotron UVX electron storage ring through the analysis of the beam profile. Transverse coherent oscillations were excited with a fast kicker and the profile of the oscillating beam was obser...
Conference Paper
Full-text available
Recent beam dynamics activities at the Brazilian Synchrotron Light Source (LNLS) are mainly directed to improve the electron storage ring performance parameters: design of a synchrotron booster to increase the injection energy, improvement in the beam orbit stability and optics calibration. In addition we have also measured the linear coupling coef...
Article
We give a derivation of the semiclassical propagator of Herman and Kluk (HK) which is based on the coherent state path integral technique. Our procedure unveils how the complex root-search problem underlying the semiclassical coherent state path integral turns into a real initial value problem and provides an explanation for the advantages of the H...
Article
Full-text available
We determine the semiclassical coherent-state propagator for a particle going through one-dimensional evolution in a simple barrier potential. The described semiclassical method makes use of complex trajectories which, by its turn, enables the definition of (real) traversal times in the complexified phase space. We then discuss the behavior of this...
Article
Full-text available
We present a commented translation of a text by Erwin Schrödinger about his article entitled: "The possibility of fulfillment of the relativity requirement in classical mechanis", which we have already translated to Portuguese.
Article
The semiclassical approximation of the coherent-state propagator requires the computation of complex trajectories satisfying special boundary conditions. In this paper we present a method for the determination of such trajectories for one-dimensional polynomial potentials. We also compute the semiclassical propagator for the caseV(q)=lambdaq2/2+bet...
Article
Full-text available
We compute the semiclassical coherent-state propagator for a particle moving in a one-dimensional box. In this semiclassical approach complex trajectories are stationary paths of the propagator{close_quote}s asymptotic expansion and play a fundamental role. A second semiclassical approximation is also introduced, which makes use of real trajectorie...
Article
Full-text available
Apresentamos uma tradução comentada de um importante artigo de Erwin Schrödinger sobre o princípio de Mach: Annalen der Physik, Volume 77, páginas 325-336 (1925), Die Erfüllbarkeit der Relativitätsforderung in der klassischen Mechanik. Abstract: We present a commented translation to Portuguese of an important article by Erwin Schrodinger on Mach's...
Article
We present a powerful and very simple method to calculate the eigenvalues of one-dimensional Hamiltonians of the form H=1/2p2+∑mk=1akx2k. The method converges extremely fast for m>=2. We show that En~n2m/(m+1) for large n and verify it numerically for m=2 and 3.

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Projects

Projects (9)
Project
Understand the possible mechanisms for propulsion using electromagnetic radiation.
Project
O presente projeto é fruto da necessidade de se entender os caminhos percorridos e a percorrer pelo Programa Espacial Brasileiro (PEB), o 4º programa espacial mais antigo do planeta, de modo a tentar esclarecer os motivos pelos quais o Brasil não obteve os resultados que outros países equivalentes em termos de representatividade mundial obtiveram. A ideia por traz desse estudo é a permitir a compreensão dos erros cometidos, a identificação de oportunidades e a definição de perspectivas futuras de modo a colaborar para atingimento de resultados que o País precisa no segmento espacial, de acordo com o contexto mundial nesse tema.