A new approach for vibration control in large space structures

An approach for augmenting vibration damping characteristics in space structures with large panels is presented. It is based on generation of bending moments rather than forces. The moments are generated using bimetallic strips, suitably mounted at selected stations on both sides of the large panels, under the influence of differential solar heating, giving rise to thermal gradients and stresses. The collocated angular velocity sensors are utilized in conjunction with mini-servos to regulate the control moments by flipping the bimetallic strips. A simple computation of the rate of dissipation of vibrational energy is undertaken to assess the effectiveness of the proposed approach

Satellite attitude motion models for capture and retrieval investigations

The primary purpose of this research is to provide mathematical models which may be used in the investigation of various aspects of the remote capture and retrieval of uncontrolled satellites. Emphasis has been placed on analytical models; however, to verify analytical solutions, numerical integration must be used. Also, for satellites of certain types, numerical integration may be the only practical or perhaps the only possible method of solution. First, to provide a basis for analytical and numerical work, uncontrolled satellites were categorized using criteria based on: (1) orbital motions, (2) external angular momenta, (3) internal angular momenta, (4) physical characteristics, and (5) the stability of their equilibrium states. Several analytical solutions for the attitude motions of satellite models were compiled, checked, corrected in some minor respects and their short-term prediction capabilities were investigated. Single-rigid-body, dual-spin and multi-rotor configurations are treated. To verify the analytical models and to see how the true motion of a satellite which is acted upon by environmental torques differs from its corresponding torque-free motion, a numerical simulation code was developed. This code contains a relatively general satellite model and models for gravity-gradient and aerodynamic torques. The spacecraft physical model for the code and the equations of motion are given. The two environmental torque models are described

Agile Literature Review

Background: Over the last 20 years the software development community has implemented agile techniques over the traditional approach to software development. Agile methods require less upfront costs and increase project flexibility; however, agile methodology is not infallible. Objective: This research seeks to validate the assumption that there is a lack of robust research regarding agile project management and its use in the software development industry. This extensive review of existing literature on the topic will serve as a basis for new research on areas with existing ambiguity. Method: The search engines used to identify relevant literature from 1987 to 2021 on the topic were Business Source Premier and Google Scholar. The procedure used to narrow the search queries was the use of deliberate keywords and phrases such as “agile software development” and “cost of requirement errors”. All results were cross-referenced on both search engines to validate the accuracy of each source. Results: 76 papers containing relevant information to agile project management within the software community have been identified: 55 academic journals, 1 book, 1 conference paper, 1 magazine article, 7 periodicals, 10 professional journals, and 1 textbook. 35 papers are critical of Agile methodology, 16 focus mostly on its strengths, 12 focus mainly on its weaknesses, and 13 contain relevant information regarding the cost of requirement errors

Space Station/Shuttle Orbiter dynamics during docking

Mathematical models of a reference space station configuration (Power Tower) and a Space Shuttle Orbiter are developed and used to study the dynamic behavior of the Space Station/Orbiter system just prior to and subsequent to an impulsive docking of the two spacecraft. The physical model of the space station is a collection of rigid and flexible bodies. The orbiter is modeled as a rigid body. An algorithm developed for use in digitally simulating the dynamics of the system is described and results of its application are presented