1,721,333 research outputs found
Uncertainty reduction of input profiles for SRS tests to prevent over-stressing: a tentative proposal to improve test specifications
No full textUncertainty evaluation and calibration of a vision-basedsystem for displacement and rotation measurement inplanetary exploration space missions
No full textIn planetary exploration space missions, motion
measurement of a vehicle on the surface of a
planet is a very important task. In this work a
visual-odometry solution is analyzed.
Particularly, a vision-based instrument for
displacement and rotation measurement is
described and calibrated using a simulated
rocky scene. The most significant uncertainty
sources are found out by experimental tests.
Different motion types are considered and the
evaluated uncertainty are compared
Introduzione alla verifica e al collaudo di sistemi meccanici per uso spaziale
No full textpubblicazione didattic
Learning how to Manage Knowledge in Large Research Projects: Drawing Inspiration From Inexpert Researchers
Full text linkComplex research projects are characterized by advanced technical-scientific goals, interactive teamwork, financial and temporal constraints. Their management is based on sophisticated project management (PM) methodologies and rigorous standards of control over deadlines and milestones, which offers the advantage that tasks are assigned and monitored with precision. However, as the studies of Knowledge Management (KM) show, researchers need a richer exhange of knowledge contents than is allowed by standard PM methods, and the burden of formal duties can make interpersonal interactions less effective. In addition, the emergence of new web 2.0 technologies gives the opportunity to exchange complex contents, and offers new ways to support the management of projects. Consequently, while it is generally agreed that PM methodologies should be a key competence of reseachers, there is the need to identify new methods that enable more effective knowledge exchanges for technical/scientific
purposes. The study investigates these issues and particularly examines if formal PM methods to exchange knowledge and manage interactions are an "automatic" solution adopted by any research team, or if researchers would spontaneously prefer flexible approaches. Particularly, it investigates the "basic KM needs" that emerge from inexpert researchers working in complex projects. The assumption is that these researchers, being less aware of the standard PM methodologies used in complex organizations, can be less conditioned with regard to the exploration of new ways to interact. At the same time, this analysis can point out the real perceptions of novice researchers about the necessity of a structured PM approach. The case study of a research team of post-graduate Engineering students is presented. The team worked in a project of a rover vehicle that competes in an ESA (European Space Agency) challenge. The way team members perceived the problems of KM and PM, and the way they decided to organize themselves to face these problems was examined by means of a systematic investigation involving direct observations of their interactions and decision making processes, surveys, and interviews to team members. The study allows to draw useful lessons for the identification and design of new PM methods, based on KM concepts and on the use of web 2.0 applications, and can also provide elements for a definition of courses of PM and KM to novice researchers
Damage detection on a plate based on proper orthogonal decomposition
No full textMonitoring the structural health of engineering systems in a nondestructive way is
becoming increasingly important, both for safety and economy reasons. Aircraft structures
are highly vulnerable to damage which may be caused over the long-term, e.g. localized corrosion,
or over the very short term, e.g. damage through impact. In the aerospace industry,
safety is paramount and successful detection of structural damage is vital in an age in which
the boundaries of materials applications are constantly being widened. Damage detection has
always been a well researched area with new techniques being continuously developed. Many
NDT methods are usually used locally for the detection of defects concentrated in small portions
of the structure. Therefore, the examination of the whole structure may require several
applications of the nondestructive techniques. It is desirable to have global NDT methods to
reveal, quickly and cheaply, the presence of damage in a zone of the structure to which a local
technique would then be effectively applied for a more accurate assessment. In general the
vibration properties, determined from the response of a structure, are mainly the natural frequencies
and the corresponding mode shapes and damping factors. Modal shape changes
seem to be more effective than natural frequency changes as damage indicators and they do
not need always a mathematical model of the structure to locate damage. This paper presents
the numerical verification on a plate of a new vibration method that was originally proposed
in Ref. [1]. The vibration properties chosen to characterize the dynamics of the structure are
derived from the theory of the proper orthogonal decomposition (POD)Ref. [2], which is
emerging as a powerful experimental tool in structural dynamics. POD provides the most efficient
way of capturing the dominant components of an infinite-dimensional process with only
a finite number of modes. This paper will present the numerical results based on the use of
acceleration values, for various damage conditions of a plate
METHOD FOR THERMAL CONDUCTIVITY AND DIFFUSIVITY MEASUREMENT SUITABLE FOR SPACE APPLICATIONS
No full textA solution method for an inverse heat conduction problem suitable for the indirect measurement of thermal conductivity and diffusivity is described. An application to an expe-rimental case is also presented. The employed method allows to reproduce typical cyclic tem-peratures and heat flow of space and planetary exploration missions. An experimental application to an insulation panel irradiated on a face and cooled on the other one is ana-lyzed. Particular attention is dedicated to uncertainty analysis, employing a Monte Carlo si-mulation in order to propagate all uncertainty sources to the indirect measurement of thermal conductivity and diffusivity. Two different hypotheses on the time correlation of the uncertain-ty sources are analyzed. Results are described and discussed for both hypotheses, allowing to obtain suitable uncertainty values for the desired output quantities
A constrained least squares approach for reaction torque control in spacecraft/manipulator systems
No full text- …
