BIRD - A Microsatellite for Hot Spot Detection

The BIRD mission of the German Aerospace Centre shall demonstrate the scientific and technological value and the technical and programmatic feasibility of a remote sensing small satellite mission under low budget constraints. The payload -a new generation of cooled infrared detectors- is adapted to the mission objective - the investigation of hot spots caused by forest fires or volcanic activities completed by the diagnosis of vegetation conditions and changes. BIRD -the Bispectral Infra-Red Detector- is a three-axis stabilised spacecraft within a volume of 0.21 m3 and a mass of 88 kg. In flight configuration with one fixed and two deployed solar panels, providing 40 W average and 200 W peak power, the spacecraft dimensions are 620x 1600x 620 mm3 • Although compatible to several launchers due to the highly compact design, the launch is scheduled for mid 2000 as a piggy-back payload. To fit in this time scale a modular design was chosen for parallel development, manufacturing and integration of all functional segments. The article gives an overview of the mission objectives and some of the main design aspects as well as shows the status of work of the space segment

International home economics

The conference was planned to serve the interests of those who wish to work in home economics programs abroad and those who are concerned with the education of international students in the universities and colleges of the United States. Approximately 165 home economists from other states and from foreign countries I including the African and Latin American countries I participated in the conference.https://lib.dr.iastate.edu/card_reports/1026/thumbnail.jp

Circular 30

Modern hybrid lilies are among the showiest perennials that can be grown by the interior Alaska gardener. There are several groups, or classes, of lilies available, not all of which are hardy here. Within a given group, there are many cultivars, which may or may not be hardy. We will, therefore, describe for you in this circular a number of lily cultivars which have proven to be hardy at the Agricultural Experiment Station at Fairbanks, and indicate those groups of lilies in which the adventurous gardener would be most likely to find additional hardy varieties

Tensile properties of concrete at very early ages

Proper knowledge of tensile properties of concrete from very early ages is essential for effective control of not only early-age cracking but also of residual stress due to restrained early-age deformation as well as for demolding and handling of young concrete members in the precast industry. Despite significant past research, such knowledge is currently inadequate and based on experimental data with questionable reliability, due mainly to the considerable challenges in testing early-age concrete. This paper first highlights the challenge and importance of collecting reliable test data on full tensile stress-deformation curves for very early-age concrete. Through identifying and effectively addressing critical drawbacks in previous test setups, an improved direct tensile testing system that can reliably capture simultaneously stress and deformation of concrete from the age of several hours after mixing has been successfully developed. Key features of the improved setup, including the air-bearing box for friction minimisation and digital image correlation for non-contact full-field deformation capturing, are then reported in the paper. Based on the newly collected data, fundamental tensile properties of concrete at very early ages are re-assessed and presented. Such properties include tensile strength, Young’s modulus, strain at peak stress, fracture energy, performance under cyclic loading and tensile relaxation

Temperature-stress testing machine - A state-of-the-art design and its unique applications in concrete research

The Temperature-Stress Testing Machine (TSTM) is a unique experimental setup that allows to study a number of fundamental properties of concrete from very early ages, thereby enabling proper assessment of cracking risk. Such critical role necessitates new constructions of TSTM with further developments to address major drawbacks in its current versions. However, there have been very limited reference sources with sufficient information to facilitate the purpose. Based on a newly-designed and built TSTM developed at The University of Queensland (UQ), Australia, the paper provides insights into its detailed design and state-of-the-art improvements. Especially, for the first time, integrated control processes for every sub-system/component are also explained in detail to supplement the lack in current reference sources and encourage future developments. Also, in this paper, verification steps to confirm the reliability and repeatability of the machine are discussed. Finally, to illustrate its practicability and capability in concrete research, the last section briefs several aspects of an on-going study at UQ utilising the TSTM to study autogenous shrinkage under various temperature histories, thermal coefficients of expansion and contraction, tensile creep, zero-stress temperature and Young's modulus, as well as their combined effects on early-age cracking risk of concrete structures. The resulting improved knowledge is expected to lead to better guidelines for effective crack control that will enable significant cost savings and more sustainable construction industry