159 research outputs found
FlexCore: Low-Cost Attitude Determination and Control Enabling High-Performance Small Spacecraft
One of the most important, yet complex, and expensive subsystems for virtually any spacecraft mission is the attitude determination and control subsystem (ADCS). Many payloads require precision ADCS to achieve the desired performance; however, such precision is typically cost-prohibitive for small spacecraft. To address this problem, Blue Canyon Technologies (BCT) has developed FlexCore, which is a highly-configurable ADCS that uses a core electronics box (based on the XACT cubesat ADCS), combined with any of the various reaction wheel sizes in the BCT product line. The FlexCore electronics and software stays the same, regardless of the spacecraft. The wide range of reaction wheel and torque rod sizes supports spacecraft sizes from large CubeSats to 100s of kilograms. The stellar-based attitude determination and control provides accuracy of 0.002-deg, RMS. Features of FlexCore include: multiple nano star trackers with integrated stray-light baffles; 3 or 4 low-jitter reaction wheels; 3 torque rods; GPS receiver; MEMS IMU; MEMS magnetometer; sun sensors; integrated processor and electronics; auto-generated flight software, including star identification, Kalman filter, momentum control, thruster control, and orbit propagation. The table-driven, auto-coded software is easily configured to support any mission, and is delivered to the user fully programmed
On-Orbit Performance of the BCT XB-1 Spacecraft and GN&C Components
Blue Canyon Technologies (BCT) currently has a variety of hardware operating in space with multiple missions launched in 2016. The deployment of the Miniature X-ray Solar Spectrometer (MinXSS) 3U CubeSat from ISS on May 16, 2016 was the first mission to operate the high accuracy pointing, complete GN&C subsystem XACT. The first on-orbit operation of the BCT XB-1 spacecraft bus occurred with the launch of the APL Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) 3U Cubesat on November 11, 2016. Finally, the NASA Cyclone Global Navigation Satellite System (CYGNSS) constellation of eight microsatellites was deployed from an Orbital ATK Pegasus XL rocket on December 15, 2016 and each spacecraft has a BCT Nano Star Tracker and three p015 reaction wheels. This paper reviews on-orbit performance of these components and systems. Detailed analysis of on-orbit telemetry is used to assess performance, with an emphasis on pointing accuracy but also including momentum control, safe mode operations, and other aspects. The results indicate a variety of solutions, ranging from high performing GN&C components to a complete spacecraft bus, capable of providing high-accuracy pointing for small satellites
MinXSS CubeSat On-Orbit Performance and the First Flight of the Blue Canyon Technologies XACT 3- axis ADCS
The Miniature X-ray Solar Spectrometer (MinXSS) 3U CubeSat was launched to the International Space Station (ISS) on 2015 December 6. Its deployment from the ISS is scheduled for 2016 March. MinXSS was designed and developed at the University of Colorado Boulder through a graduate project class, with significant professional support from the Laboratory for Atmospheric and Space Physics (LASP). The 3- axis attitude determination and control system (ADCS) is the Blue Canyon Technologies (BCT) XACT. This is the first flight of the XACT unit, which is the most capable commercially available 3-axis ADCS for CubeSats on the market today.
MinXSS is a science mission funded by NASA\u27s Heliophysics division and is the first CubeSat to be flown from NASA Science Mission Directorate\u27s new CubeSat Implementation Panel. The primary objective for the MinXSS mission is to better understand the energy distribution of solar soft x-ray (SXR) emissions and their impact on earth\u27s ionosphere, thermosphere, and mesosphere (ITM). MinXSS observes the solar SXR spectrum between 0.5 to 30 keV with an energy resolution of 0.15 keV full width half maximum at 5.9 keV. Very few prior spectrally-resolved solar observations exist in the SXR range, leaving a critical gap in our ability to determine the spectral energy distribution for ITM modeling and solar flare studies. These issues can be addressed with new MinXSS data.
This paper will provide details of the on-orbit performance of MinXSS and first-light observations from the primary science instrument, which is a commercially available system that was modified for flight.
First light observations will include the first solar SXR spectrum from MinXSS and comparisons between quiet-Sun and flare spectra as observed by MinXSS.
MinXSS represents the first opportunity for on-orbit characterization of BCT\u27s XACT ADCS. Performance of star tracker-based attitude determination, 3-axis reaction wheel-based attitude control, and torque rod-based momentum control will be assessed using on-orbit telemetry. This system is being used by several NASA centers, the DoD, many universities, and commercial entities for a multitude of upcoming missions that require precision attitude control at low cost.
The exceptionally simple design of the LASP PPPT will be reviewed. The addition of a single fixed-value resistor mitigates the high current draw from the battery, which prevents the solar cell voltage from dropping below buck converter input requirements. The PPPT was successful in increasing the power output of the electrical power system by nearly a factor of 2 in mission simulations. The on-orbit power performance will be analyzed.
In addition to thermal vacuum testing, MinXSS underwent thermal balance, which is dedicated to tuning the thermal model. The thermal balance procedure and model will be briefly overviewed and predictions compared to on-orbit temperatures. The results of this analysis have been generalized such that other CubeSat programs, who may not have the means to perform the test, may apply the results to their models and get improved model predictions. Thermal control of CubeSats is important to their lifetime and few if any prior results on this topic have been previously presented
Oldest Systematic Program of German Idealism: Translation and Notes
This book’s goal is to give an intellectual context for the following manuscript.
Includes bibliographical references and an index. Pages 1-123.
1). Philosophy. 2). Metaphysics. 3). Philosophy, German. 4). Philosophy, German -- 18th century. 5). Philosophy, German and Greek Influences Metaphysics. I. Hegel, Georg Wilhelm Friedrich -- 1770-1831 -- Das älteste Systemprogramm des deutschen Idealismus. II. Rosenzweig, Franz, -- 1886-1929. III. Schelling, Friedrich Wilhelm Joseph von, -- 1775-1854. IV. Hölderlin, Friedrich, -- 1770-1843. V. Ferrer, Daniel Fidel, 1952-. [Translation from German into English of the-- Das älteste Systemprogramm des deutschen Idealismus.].
Note: the manuscript is in the handwriting of G.W.F. Hegel, but the actual authorship is disputed. No date is given. Franz Rosenzweig made up the title as it is known today. He published the text in 1917. At that time, F. Rosenzweig thought F.W.J. Schelling was the author.
No one has read this book for errors. As always, any errors, mistakes or oversights etc. are mine alone. Given a couple more years, I could improve this book. This is a philosophical translation and not a philological translation. Martin Luther who did the famous early translation of the Bible into German wrote in a letter, “If anyone does not like my translation, they can ignore it… (September 15, 1530)”.
There are no ‘correct’ translations. Some are just better than other translations.
The Oldest Systematic Program of German Idealism. The German title is: Das Älteste Systemprogramm Des Deutschen Idealismus. This title was made up by Franz Rosenzweig in 1917, when he first published the manuscript. He found the manuscript in the Royal Library in Berlin in 1913. The manuscript suggested date is around 1796 and was done by handwriting research. However, the manuscript is not dated. The Prussian State Library auctioned in March 1913 from the auction of the house Liepmannssohn in Berlin a single sheet on the front and back with Hegel's cursive handwriting. The manuscript was lost during WWII. But Dieter Henrich found it again in 1979 in the “Biblioteka Jagiellonska” in Krakow (Poland), where it is today. Address: Jagiellonian Library, Jagiellonian University, al. Mickiewicza 22, 30-059 Cracow, Poland. Later research suggests that manuscript had come from the estate of Hegel’s student Friedrich Christoph Förster (1791-1868). He was one of the editors of Hegel’s posthumous works and most likely had access to a number of Hegel’s manuscripts. This text actually being one of them. Hegel traveled around Bohemia with Marie and Friedrich Christoph Förster around the year 1820-21 (see Klaus Vieweg).
Philosophical mystery -- who is the author or authors of this text?
Take a plunge into the deep and cold waters. Maybe a quagmire or quandary, but decidedly interesting. This project is to contextualize an old handwritten manuscript which is about 225 years old. The actual author is a mystery. I offer my own assessment. You can make your own assessments. The mystery has continued to unfold since 1917. There is plenty to read.
Otherwise, think about the authorship and read more of the German philosophers and authors from this period and enjoy the depth of thinking and philosophizing. On one hand, there is just the sheer fun in the puzzle of the authorship questions; and on the other hand, these are the alluring thoughts that lead to the nascent stage of German Idealism and our intellectual heritage. There is no end to the accolades for this group of philosophers. A heritage that we still hear in in our attempts to move forward into our future.
Do your own astute exegesis (ἐξήγησις) as all paths are still open. Let your thought take to the wings of what is called thinking with this text. Critical encounters (Auseinandersetzung, or a Gegenüberstellung) with at least: Friedrich Hölderlin (1770-1843) Friedrich Wilhelm Joseph Schelling (1775-1854), and Georg Wilhelm Friedrich Hegel (1770-1831) --- starts here! German Idealism. We are not going to study this situation endlessly, instead we make some broad strokes and provide you a general context. You are allowed to read between the lines too. Goal: to understand the overall affinity and differences between the intellectuals of this period in German history; and to come to grips with this demanding text within its large scholarly context in the last 100 years. There are no final answers
The Household Responsibility System, Karl Marx’s Theory of Property and Antony M. Honoré’s Concept of Ownership
The Household Responsibility System (HRS) has improved agricultural productivity and promoted economic growth and thus relieved poverty in the rural population of China. However, the prevailing assumptions about its nature are that it was the result of de-collectivization and privatization (or at least semi-privatization) of land and thus an adaptation of capitalism or semi-capitalism. Moreover, the property rights structure of the HRS in China is also often assumed to be ambiguous and insecure. Grasping the principal characteristics of the HRS requires historical analysis of its origin, development and eventual legislation and institutionalization. Marx's theory of property is the key to understanding the institutional change from the Commune System to the HRS. It reveals that the HRS is one kind of “individual property” that Marx envisioned in post-capitalist society. Antony M. Honoré's theoretical framework of ownership is usefully viewed as a development of Marx's theory; within that framework, the HRS emerges as a kind of “split ownership” and its property rights structure can be judged to be well-defined
The depression in visual impairment trial (DEPVIT): trial design and protocol
<b>Background</b>
The prevalence of depression in people with a visual disability is high but screening for depression and referral for treatment is not yet an integral part of visual rehabilitation service provision. One reason for this may be that there is no good evidence about the effectiveness of treatments in this patient group. This study is the first to evaluate the effect of depression treatments on people with a visual impairment and co morbid depression.<p></p>
<b>Methods/design</b>
The study is an exploratory, multicentre, individually randomised waiting list controlled trial. Participants will be randomised to receive Problem Solving Therapy (PST), a ‘referral to the GP’ requesting treatment according to the NICE’s ‘stepped care’ recommendations or the waiting list arm of the trial. The primary outcome measure is change (from randomisation) in depressive symptoms as measured by the Beck’s Depression Inventory (BDI-II) at 6 months. Secondary outcomes include change in depressive symptoms at 3 months, change in visual function as measured with the near vision subscale of the VFQ-48 and 7 item NEI-VFQ at 3 and 6 months, change in generic health related quality of life (EQ5D), the costs associated with PST, estimates of incremental cost effectiveness, and recruitment rate estimation.<p></p>
<b>Discussion</b>
Depression is prevalent in people with disabling visual impairment. This exploratory study will establish depression screening and referral for treatment in visual rehabilitation clinics in the UK. It will be the first to explore the efficacy of PST and the effectiveness of NICE’s ‘stepped care’ approach to the treatment of depression in people with a visual impairment.<p></p>
Kierkegaard on Truth: One or Many?
This paper re-examines Kierkegaard's work with respect to the question whether truth is one or many. I argue that his famous distinction between objective and subjective truth is grounded in a unitary conception of truth as such: truth as self-coincidence. By explaining his use in this context of the term ‘redoubling’ [Fordoblelse], I show how Kierkegaard can intelligibly maintain that truth is neither one nor many, neither a simple unity nor a complex multiplicity. I further show how these points shed much-needed light on the relationship between objective and subjective truth, conceived not as different kinds or species of truth but as different ways in which truth manifests itself as a standard of success across different contexts of inquiry
Waste, Industry and Romantic Leisure: Veblen's Theory of Recognition
types: ArticleVeblen’s work contains a neglected, since for the most part implicit, theory of recognition centred on his concepts of waste and workmanship. This article tries to develop this theory in order to shed new light on the theorem of conspicuous leisure and consumption. The legitimacy of violence at the ‘predatory stage’ of culture has been partly superseded by a legitimacy of industrial efficiency, so that the leisure classes need to disguise their conspicuous waste as socially useful productive endeavours. At the same time waste remains a powerful symbol of legitimate status, so that even the industrial classes turn to it in order to assert their social worth and demand social recognition. Waste - which is far more central in Veblen’s theory than is emulation - becomes an ambiguous symbol which can stand for both unproductive privilege and industrial efficiency. The utilitarian urge for efficiency and the meaninglessness of a struggle for recognition through conspicuous waste produce a desire for a romantic escape, also acknowledged by Veblen, but often overlooked in his sharp criticism of consumerism
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