On the Development of SCILAB Compatible Software for the Analysis and Control of Repetitive Processes

In this paper further results on the development of a SCILAB compatible software package for the analysis and control of repetitive processes is described. The core of the package consists of a simulation tool which enables the user to inspect the response of a given example to an input, design a control law for stability and/or performance, and also simulate the response of a controlled process to a specified reference signal

PACOSS program overview and status

Many future civilian and military large space structures (LSS) will have as performance objectives stringent pointing accuracies, short settling times, relatively fast response requirements, or combinations thereof. Many of these structures will be large, light weight, and will exhibit high structural modal density at low frequency and within the control bandwidth. Although it is possible in principle to achieve structural vibration control through purely active means, experience with complex structures has shown that the realities of plant model inaccuracies and sensor/actuator dynamics frequently combine to produce substandard performance. A more desirable approach is to apply passive damping technology to reduce the active control burden. Development of the technology to apply this strategy is the objective of the PACOSS (Passive and Active Control OF Space Structures) program. A key element in the PACOSS program is the Representative System Article (RSA). The RSA is a generic paper system that serves as a testbed for damping and controls studies. It also serves as a basis for design of the smaller Dynamic Test Article (DTA), a hardware testbed for the laboratory validation of analysis and design practices developed under PACOSS

On controllability and control laws for discrete linear repetitive processes

Repetitive processes are a distinct class of 2D systems (i.e. information propagation in two independent directions) of both systems theoretic and applications interest. They cannot be controlled by the direct extension of existing techniques from either standard (termed 1D here) or 2D systems theory. This article develops significant new results on the relationships between one physically motivated concept of controllability for the so-called discrete linear repetitive processes and the structure and design of control laws, including the case when disturbances are present

Control and Filtering for Discrete Linear Repetitive Processes with H infty and ell 2--ell infty Performance

Repetitive processes are characterized by a series of sweeps, termed passes, through a set of dynamics defined over a finite duration known as the pass length. On each pass an output, termed the pass profile, is produced which acts as a forcing function on, and hence contributes to, the dynamics of the next pass profile. This can lead to oscillations which increase in amplitude in the pass to pass direction and cannot be controlled by standard control laws. Here we give new results on the design of physically based control laws for the sub-class of so-called discrete linear repetitive processes which arise in applications areas such as iterative learning control. The main contribution is to show how control law design can be undertaken within the framework of a general robust filtering problem with guaranteed levels of performance. In particular, we develop algorithms for the design of an H? and $\ell_{2}–\ell_{\infty}$ dynamic output feedback controller and filter which guarantees that the resulting controlled (filtering error) process, respectively, is stable along the pass and has prescribed disturbance attenuation performance as measured by $H_{\infty}$ and $\ell_{2}$–$\ell_{\infty}$ norms

A 2D systems approach to iterative learning control for discrete linear processes with zero Markov parameters

In this paper a new approach to iterative learning control for the practically relevant case of deterministic discrete linear plants with uniform rank greater than unity is developed. The analysis is undertaken in a 2D systems setting that, by using a strong form of stability for linear repetitive processes, allows simultaneous con-sideration of both trial-to-trial error convergence and along the trial performance, resulting in design algorithms that can be computed using Linear Matrix Inequalities (LMIs). Finally, the control laws are experimentally verified on a gantry robot that replicates a pick and place operation commonly found in a number of applications to which iterative learning control is applicable

Structural optimization of an alternate design for the space shuttle solid rocket booster field joint

A structural optimization procedure is used to determine the shape of an alternate design for the shuttle solid rocket booster field joint. In contrast to the tang and clevis design of the existing joint, this alternate design consists of two flanges bolted together. Configurations with 150 studs of 1 1/8 in. diameter and 135 studs of 1 3/16 in. diameter are considered. Using a nonlinear programming procedure, the joint weight is minimized under constraints on either von Mises or maximum normal stresses, joint opening and geometry. The procedure solves the design problem by replacing it by a sequence of approximate (convex) subproblems; the pattern of contact between the joint halves is determined every few cycles by a nonliner displacement analysis. The minimum weight design has 135 studs of 1 3/16 in. diameter and is designed under constraints on normal stresses. It weighs 1144 lb per joint more than the current tang and clevis design

Correction to: Parent and teacher perceptions of NAPLAN in a sample of Independent schools in Western Australia (The Australian Educational Researcher, (2018), 45, 4, (493-513), 10.1007/s13384-018-0270-2)

The article “Parent and teacher perceptions of NAPLAN in a sample of Independent schools in Western Australia”, written by S. L. Rogers, L. Barblett and K. Robinson was originally published electronically on the publisher’s internet portal (currently SpringerLink) on 3 April 2018 without open access. © 2019, The Author(s)

An integrated review program for the preparation for the United States medical license examination (USMLE)

The primary objective of the present educational research program is to improve upon existing commercially available USMLE review programs. With the clear shortage of both residency slots, the medical student's performance (score), on the USMLE assumes a new and critical importance. Furthermore, there is a global need for 4.3 million new doctors and nurses. This shortage is particularly evident in Central and Southeast Asia. Many of the needed new doctors will most probably be required to pass the USMLE

The development of cryogenic storage systems for space flight

Development of cryogenic storage systems for manned space fligh

Running to well-being: A comparative study on the impact of exercise on the physical and mental health of law and psychology students

Research indicates that, in comparison to other university students, law students are at greater risk of experiencing high levels of psychological distress. There is also a large body of literature supporting a general negative association between exercise and stress, anxiety and depression. However, we are not aware of any studies exploring the impact of exercise on the mental health of law students specifically. This article reports evidence of a negative association between exercise and psychological distress in 206 law and psychology students. Compared to psychology students, the law students not only reported greater psychological distress, but, in addition, there was a stronger association between their levels of distress and their levels of exercise. Based on the results of this study, we suggest a simple yet effective way law schools might support the mental health of their students