Ground demonstration of a solar sail attitude control actuator

Recently there has been renewed interest in solar sails as an alternative means of space propulsion. Many different attitude control systems have been designed for Solar Sails taking advantage of the centre-of-mass(cm)/centre-of- pressure(cp) offset. Most of these proposed systems are at best theoretical and have not been demonstrated. In this paper we build upon a previous proposed scalable bus-based attitude control system for solar sails, which utilised a trim control mass actuator to change the centre of mass and highly reective panels to create a windmill torque, achieving 3-axis control. As part of testing the proposed system, we have built and demonstrated a trim control mass actuation mechanism for solar sails, taking advantage of an air-bearing table to achieve a virtually frictionless attitude test environment. This is the first known attempt at construction and demonstration of a solar sail attitude control system based on the change in the cm with respect to the cp. In this paper we seek to investigate the control algorithms involved and the obstacles concerned in building a trim control mass actuator for a solar sail. Copyright © 2010 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved

BIM-Enabled Structural Design: Impacts and Future Developments in Structural Modelling, Analysis and Optimisation Processes

This review focuses on identifying the impacts and future development trends for current structural design practice in integration of building information modelling (BIM) technologies. BIM technologies, as novel information management schemes they are, are changing the conventional structure design processes. Currently, utilising BIM technologies for reshaping structural design has been widely acknowledged and embraced by both academic and industry circles. In this research, the current status and issues of the structural design processes (including modelling, analysis, and optimisation of structures) are fully investigated with emphases on specific design stages. The research put efforts on surveying the benefits of BIM in facilitating current structural design, such as systematic modelling processes, powerful interactive visualization platform, and standardised exchanging data interfaces. Impacts of personnel involvement in structural design when adopting BIM have also been identified in detail. Finally, a predicted cross-functional flowchart of BIM-enabled structural design for the near future is proposed, which shows future developing trends in improving structural design quality and addressing current issues

Guidelines for the use and interpretation of assays for monitoring autophagy.

In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field