116,601 research outputs found
Michael Tisserand - 10/18/2007 - (Riall Lecture Series)
No full textBegun in 1988, the E. Pauline Riall Lecture Series brings to the University and community outstanding national lecturers in the field of education. The series was established by the late Miss Riall, long-time principal and teacher of the former Salisbury University's Campus School. A generous bequest was provided by Miss Riall's will to fund this special program.
Mr. Michael Tisserand, journalist and author of: Sugarcane Academy: How a New Orleans Teacher and His Storm-struck Students Created a School to Remember - Riall Speaker on 10/17/2007 (pm) and 10/18/2007 (am).https://www.youtube.com/watch?v=FsCUocW1hi
Michael Tisserand - 10/17/2007 - (Riall Lecture Series)
No full textBegun in 1988, the E. Pauline Riall Lecture Series brings to the University and community outstanding national lecturers in the field of education. The series was established by the late Miss Riall, long-time principal and teacher of the former Salisbury University's Campus School. A generous bequest was provided by Miss Riall's will to fund this special program.
Mr. Michael Tisserand, journalist and author of: Sugarcane Academy: How a New Orleans Teacher and His Storm-struck Students Created a School to Remember - Riall Speaker on 10/17/2007 (pm) and 10/18/2007 (am).https://www.youtube.com/watch?v=CFvnYbL5m4
The Extended Tisserand-Poincaré graph for multi-body trajectory design
No full textThe decision on the dynamical model used to design a spacecraft’s trajectory is a fundamental choice influenced by many factors. The complexity of such a model affects the accuracy of the designed trajectory but also the difficulty of the design process. One approach to simplify this task consists of splitting the trajectory design process into two phases. In the first phase a first-guess reference trajectory is generated through the usage of a simple dynamical model considering the most important forces in the system. In the second phase this reference trajectory is taken and refined with the addition of the perturbing forces that have been neglected in the first phase. The success of this approach depends on the proper sharing of the perturbing forces between the two phases. In this sense the backbone of the trajectory is designed in the first phase and it is fundamental that in this phase the main forces are taken into account to not avoid to consider them as negative perturbing effects in the second phase, that often is performed using an optimization technique.The research covered in this report is focused on the first phase of this process, in particular for what concerns the gravitational influences generated by multiple bodies. In this sense the simplest dynamical model that could be used considers only the gravitational influence of the main attracting body. Such model however is not able to capture interesting and useful phenomena existing in a more realistic multi-body environment that allow to save a considerable amount of ∆V . This aspect is of crucial importance for missions such as EQUULEUS and DESTINY, whose limited ∆V capabilities need to be compensated by a clever design process actively exploiting both lunar and solar perturbation effects. This is achieved in this research through the usage of a patched Circular Restricted Three-Body Problem model describing the motion of the spacecraft under the influence of two primaries at a time. Such a patched model is an approximated model that represents the trajectory of a spacecraft under the influence of three bodies. A graphical technique called Tisserand-Poincaré graph exploits this dynamical model to design trajectories in several multi-body environments. The applicability of this technique however is strongly tied to the definition of the so-called Tisserand parameter. The latter however exists only about the primary, limiting the patching between different Circular Restricted Three-Body Problems to those systems sharing the most attracting body such as the Jupiter-Europa-Ganymede or Sun-Earth-Jupiter systems. To overcome this limitation, that would make it impossible to apply the same technique in the Sun-Earth-Moon system for the EQUULEUS and DESTINY missions, the theoretical framework of the technique is extended in this research. In particular a modified version of the Tisserand parameter defined about the secondary that possesses the same constancy property of the classical Tisserand parameter but on a specifically defined family of Poincaré sections is derived. The concept of the modified Tisserand parameter is based on a relationship between the parameter and the Jacobi constant of the system that can be expressed by the fundamental equation J = T +P .The new parameter and associated Poincaré sections are used to characterize the Earth-Moon and Sun-Earth systems. Through the usage of a graphical tool, the definition of the modified parameter and the definition of a specific family of Poincaré sections, both solar and lunar perturbations are characterized and exploited in the trajectory design process in the multi-body environment. A database approach to be used for the EQUULEUS trajectory design in a quasi-four body problem is developed. Databases of flyby trajectories about the Moon and Jupiter in the Earth-Moon and Sun-Jupiter CR3BP models are also developed. A standard patching procedure is tested in the Sun-Jupiter-Europa environment to demonstrate a capture trajectory about Jupiter.Aerospace Engineerin
On the ballistic capture of asteroids for resource utilisation
No full textThis paper investigates the concept of capturing in the Earth’s neighbourhood Earth-approaching objects such as asteroids and comets. These objects may provide access to potential resources, as well as be potential scientific mission opportunities. A statistical approach is used to assess the fraction of the near-Earth object population with a given set of Keplerian elements. This is used to estimate the number of objects with the potential to fly-by the Earth with low relative velocities. The circular restricted three-body problem is then used to show that objects approaching Earth at low hyperbolic excess velocities can potentially be gravitationally captured at Earth. The Tisserand parameter, used as an approximation of the Jacobi constant, can be used to delimit the orbital regions from were low-energy transfers should be expected to exist and asteroids could possibly be transported at a minimum expenditure of energy. Finally, a semi-analytical approximation of the gravitational perturbation in the CR3BP is used to assess the feasible asteroid transport fluxes of capturable material that could be achieved by judicious use of Earth gravitational perturbations
author-bios-SRD-19-0063.R1 – Supplemental material for The Network Structure of Police Misconduct
No full textSupplemental material, author-bios-SRD-19-0063.R1 for The Network Structure of Police Misconduct by George Wood, Daria Roithmayr and Andrew V. Papachristos in Socius</p
Design and Measurement of Integrated Converters for Belt-driven Starter-generator in 48 V Micro/mild Hybrid Vehicles
No full textWith reference to a 48 V belt-driven starter-generator, used in micro/mild hybrid vehicles, the paper shows the design and measurement of an integrated H-bridge and of a compact DC/DC converter, both fabricated in low-cost HV-MOS technology. The H-bridge is in charge of rotor excitation and, thanks to a direct copper bonding of the HV-MOS devices on a ceramic substrate, it ensures a full-integrated solution with low ON-resistance values. The compact DC/DC converter interfaces the 48 V power domain with the lower voltage domain of sensing and control electronics, such as 5 V and 1.65 V in this case study, without using cumbersome inductors and transformers. The latter are difficult to integrate in silicon technology. The converter has a multi stage architecture, where each stage implements a switched capacitor regulation. Multiple voltage outputs are supported, with a configurable regulation factor, sustaining an input voltage variation from 6 V (in case of cranking) up to 60 V. Specific design techniques have been implemented to reduce electromagnetic interference (EMI), typical of switching converters. Experimental measurements on fabricated prototype chipsets confirm the suitability of the presented designs for low-EMI 48 V application
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
DC/DC converter integrated architecture for 48V supplies in micro/mild hybrid vehicle electrical engine control module
No full textThe paper shows the design in low-cost HV-CMOS technology of an integrated DC/DC converter for a 48 V electrical belt system generator-alternator used in micro/mild hybrid vehicles. Aiming at interfacing the 48 V power domain with a lower voltage domain, but without using cumbersome inductors and transformers, difficult to integrate in CMOS technology, the DC/DC converter exploits a multi stage architecture. Each stage is a switched capacitor unit. Multiple voltage outputs are supported with a configurable regulation factor, so that the same converter acts in step down or step up mode sustaining an input voltage variation from 6 V (in case of cranking) up to 60 V
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