Viking Orbiter 1975 thrust vector control system accuracy

The thrust vector control (TVC) system of the Viking Orbiter 1975 is discussed. The purpose of the TVC system is to point the engine thrust at the vehicle center of mass and to maintain attitude stability during propulsive maneuvers. This is accomplished by mounting the engine in a two-axis gimbal system. The TVC system then controls the pointing of the engine by closed loop control of two linear actuators which extend or retract and rotate the engine in its gimbal system. The effect of the TVC on the velocity vector pointing error incurred during a propulsive maneuver is analyzed. Models for predicting the magnitude of the error for various propulsive maneuvers are developed

Breakage functions of particles of four different materials subjected to uniaxial compression

Particle breakage is a common problem in the conveying and handling of particulate solids. The phenomenon of particle breakage has been studied by experiments by a number of researchers in order to describe the process of breakage by mathematical functions. The development of comminution functions that can suitably describe the breakage behavior of granular materials can lead to a significant improvement in the design and efficiency of particulate solids handling equipment. The present study focuses on developing the strength distribution and the breakage functions of particles of four different materials subjected to uniaxial compressive loading. Single particles were compressed until fracture in order to determine their strength distribution and the fragments were investigated to determine their size distribution. The parameters of logistic function and breakage function were obtained by curve-fitting of the functions to the strength distribution and size distribution of the fragments respectively. These functions were then implemented in the BGU-DEM code which was used to carry out Discrete Element Method (DEM) simulations on single particle breakage by compression. The simulations produced a similar mass distribution of fragments to the breakage function obtained from the experimental data

International relations theory

This book is designed as a foundational entry point to International Relations theory. Like other books in the E-IR Foundations series, this takes the form of an engaging narrative, connecting the reader directly to the issues at hand. The first half of the book covers the theories that are most commonly taught in undergraduate programmes. The book then expands to present emerging approaches and offer wider perspectives. Each chapter sets out the basics of a theory whilst also applying it to a real-world event or issue, creating a lively, readable and relevant guide that will help students to see not only what theories are – but why they matter