Edmund Spenser - Amoretti

Tradução de: Eugênio Gardinalli Filho

Optoelectronic fiber interface design

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.Includes bibliographical references (p. 67).Recent developments in materials science have led to the development of an exciting, new class of fibers which integrate metals, semiconductors and insulators in the same codrawing process. Various electrical devices have been produced in these fibers including optical sensors, thermal sensors and even transistors. The use of these fiber devices in a variety of applications was explored. A large-scale, lensless imager, an optical communication system, a thermal sensing array and a logic gate were designed to use appropriate classes of electrically active fibers. These devices were constructed with a particular focus on testing the best ways to integrate these fibers with modern circuits. Several methods of making electrical contact with fibers are described and their failure modes are discussed and novel circuits for amplifying and measuring fiber signals are developed and presented.by Matthew Edmund Spencer.M.Eng

A Dual-Band Circularly Polarized Printed Antenna for Deep Space CubeSat Communication

This paper presents the design of a dual-band printed planar antenna for deep space CubeSat communications. The antenna system will be used with a radio for duplex operation in a CubeSat, which can be used for a lunar mission or any deep space mission. While a high-gain CubeSat planar antenna/array is always desired for a deep space mission, high-performance ground stations are also required for robust communication links. For such a mission, the X-band is the appropriate frequency for the downlink communication,which is very challenging in the case of deep space communication compared to the uplink communication. At this frequency, the antenna size can have small enough dimension to form an array to obtain high-gain directional radiations for the successful communication, including telemetry and data download. NASA’s Deep Space Network (DSN) has the largest and most sensitive 70 meter-diameter antenna that can be considered for this type of mission for reliability. DSN has uplink and downlink frequency of operations in 7.1-GHz and 8.4-GHz bands, respectively, which are separated by approximately 1.3 GHz. A straight forward approach is to use two antennas to cover uplink and downlink frequencies. However, CubeSats have huge space constraints to accommodate science instruments and other subsystems and commonly utilize outside faces for solar cells. Therefore, in this paper, we have proposed a planar directional circularly polarized antenna with a single feed that operates at both uplink and downlink DSN frequencies. Simulated 3-dB axial ratio bandwidth of 165MHz, from 7064MHz to 7229MHz for uplink, and that of 183MHz, from 8325 MHz to 8508 MHz for downlink, are achieved. Also, a wide impedance bandwidth of 23.86% (VSWR \u3c 2) is obtained. From this single probe-fed stacked patch antenna, peak RHCP gain of 9.24dBic can be achieved

Women in physics in the United States: Recruitment and retention

Initiatives to increase the number, persistence, and success of women in physics in the United States reach preteen girls through senior women. Programs exist at both the local and national levels. In addition, researchers have investigated issues related to gender equity in physics and physics education. Anecdotal evidence suggests increased media coverage of the underrepresentation of women in science. All of these efforts are motivated and made more effective by the continued collection and presentation of data on the presence, persistence, and promise of women in physics

Seduced by System: Edmund Burke's Aesthetic Embrace of Adam Smith's Philosophy

No abstract available

The Seoul National University AGN Monitoring Project III: Hβ\beta lag measurements of 32 luminous AGNs and the high-luminosity end of the size--luminosity relation

We present the main results from a long-term reverberation mapping campaign carried out for the Seoul National University Active Galactic Nuclei (AGN) Monitoring Project. High-quality data were obtained during 2015-2021 for 32 luminous AGNs (i.e., continuum luminosity in the range of $10^{44-46}$ erg s$^{-1}$) at a regular cadence, of 20-30 days for spectroscopy and 3-5 days for photometry. We obtain time lag measurements between the variability in the H$\beta$ emission and the continuum for 32 AGNs; twenty-five of those have the best lag measurements based on our quality assessment, examining correlation strength, and the posterior lag distribution. Our study significantly increases the current sample of reverberation-mapped AGNs, particularly at the moderate to high luminosity end. Combining our results with literature measurements, we derive a H$\beta$ broad line region size--luminosity relation with a shallower slope than reported in the literature. For a given luminosity, most of our measured lags are shorter than the expectation, implying that single-epoch black hole mass estimators based on previous calibrations could suffer large systematic uncertainties.Comment: Accepted by ApJ; 39 pages, 22 figure

Variability and the size-luminosity relation of the intermediate mass AGN in NGC 4395

We present the variability study of the lowest-luminosity Seyfert 1 galaxy NGC 4395 based on the photometric monitoring campaigns in 2017 and 2018. Using 22 ground-based and space telescopes, we monitored NGC 4395 with a $\sim$5 minute cadence during a period of 10 days and obtained light curves in the UV, V, J, H, and K/Ks bands as well as the H$\alpha$ narrow-band. The RMS variability is $\sim$0.13 mag on \emph{Swift}-UVM2 and V filter light curves, decreasing down to $\sim$0.01 mag on K filter. After correcting for continuum contribution to the H$\alpha$ narrow-band, we measured the time lag of the H$\alpha$ emission line with respect to the V-band continuum as ${55}^{+27}_{-31}$ to ${122}^{+33}_{-67}$ min. in 2017 and ${49}^{+15}_{-14}$ to ${83}^{+13}_{-14}$ min. in 2018, depending on the assumption on the continuum variability amplitude in the H$\alpha$ narrow-band. We obtained no reliable measurements for the continuum-to-continuum lag between UV and V bands and among near-IR bands, due to the large flux uncertainty of UV observations and the limited time baseline. We determined the AGN monochromatic luminosity at 5100\AA\ $\lambda L_\lambda = \left(5.75\pm0.40\right)\times 10^{39}\,\mathrm{erg\,s^{-1}}$, after subtracting the contribution of the nuclear star cluster. While the optical luminosity of NGC 4395 is two orders of magnitude lower than that of other reverberation-mapped AGNs, NGC 4395 follows the size-luminosity relation, albeit with an offset of 0.48 dex ($\geq$2.5$\sigma$) from the previous best-fit relation of Bentz et al. (2013).Comment: Accepted for publication in ApJ (Feb. 23rd, 2020). 18 pages, 10 figure

2020 roadmap on solid-state batteries

Li-ion batteries have revolutionized the portable electronics industry and empowered the electric vehicle (EV) revolution. Unfortunately, traditional Li-ion chemistry is approaching its physicochemical limit. The demand for higher density (longer range), high power (fast charging), and safer EVs has recently created a resurgence of interest in solid state batteries (SSB). Historically, research has focused on improving the ionic conductivity of solid electrolytes, yet ceramic solids now deliver sufficient ionic conductivity. The barriers lie within the interfaces between the electrolyte and the two electrodes, in the mechanical properties throughout the device, and in processing scalability. In 2017 the Faraday Institution, the UK's independent institute for electrochemical energy storage research, launched the SOLBAT (solid-state lithium metal anode battery) project, aimed at understanding the fundamental science underpinning the problems of SSBs, and recognising that the paucity of such understanding is the major barrier to progress. The purpose of this Roadmap is to present an overview of the fundamental challenges impeding the development of SSBs, the advances in science and technology necessary to understand the underlying science, and the multidisciplinary approach being taken by SOLBAT researchers in facing these challenges. It is our hope that this Roadmap will guide academia, industry, and funding agencies towards the further development of these batteries in the future

Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð¥with constraintsð ð 𥠥 ðandð´ð¥ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis