Spacecraft attitude sensor

A system for sensing the attitude of a spacecraft includes a pair of optical scanners having a relatively narrow field of view rotating about the spacecraft x-y plane. The spacecraft rotates about its z axis at a relatively high angular velocity while one scanner rotates at low velocity, whereby a panoramic sweep of the entire celestial sphere is derived from the scanner. In the alternative, the scanner rotates at a relatively high angular velocity about the x-y plane while the spacecraft rotates at an extremely low rate or at zero angular velocity relative to its z axis to provide a rotating horizon scan. The positions of the scanners about the x-y plane are read out to assist in a determination of attitude. While the satellite is spinning at a relatively high angular velocity, the angular positions of the bodies detected by the scanners are determined relative to the sun by providing a sun detector having a field of view different from the scanners

Biogas appliances in Sub-Sahara Africa

Acknowledgement The authors are grateful to DFID for the financial support granted through The New and Emerging Technologies Research Competition (NET-RC). We also want to thank numerous authors, staff at CREEC and Uganda Domestic program who work tirelessly to provide the know-how, books, articles on biogas technology whose works were made reference to.Peer reviewedPostprin

Wet Slip Resistance of Plastic Based Material Flooring (PBM Flooring)

Tile Council of North America Product Performance Testing Laboratory, under the direction of Dr. John Sanders of the Bishop Materials Laboratory at Clemson University, measured the wet Dynamic Coefficient of Friction (DCOF) of 22 plastic based material (PBM1) flooring products that manufacturers2 advertise or claim to be waterproof, water resistant, or depict being used in areas where flooring gets wet.3 The claims suggest that such PBM products can be used where exposed to water. However, product literature for only five products tested in this report cautioned the products can be potentially slippery when wet, and no measurements of wet DCOF are provided by the product manufacturers for any of the PBM flooring products studied.4 This research examines whether the tested products are suitable for wet use, or instead should carry a dry use-only caution. ANSI A326.3, American National Standard Test Method for Measuring Dynamic Coefficient of Friction of Hard Surface Materials, was used to measure the wet DCOF of each PBM product. The ANSI A326.3 test method was developed through a broad consensus of stakeholders across the flooring industry and is widely used in the ceramic tile, polished concrete, and stone industries.5 The ANSI A326.3 testing showed 16 out of the 22 product specimens tested in this report had an average wet DCOF value below 0.42. Per ANSI A326.3, those 16 specimens are not suitable for wet use,6 although each tested product was advertised as waterproof, water resistant, or was depicted being used in areas where flooring gets wet. In addition, two out of 22 product specimens’ DCOF measured below 0.42 when tested parallel to the plank length, but above 0.42 when tested perpendicular to the plank length. These two products exhibited a potentially dangerous level of directionality (See Section 3.6.3) with a significant change in DCOF occurring depending on the direction of measurement. Further, four other products exhibited directionality. In total, 20 of the 22 products tested for this report exhibited either a low level of wet DCOF for products that are advertised for wet applications (18 of 22) or directionality when wet (6 of 22)7, and should be considered for a dry use-only cautionary statement

Speech coding at 4800 bps for mobile satellite communications

A speech compression project has recently been completed to develop a speech coding algorithm suitable for operation in a mobile satellite environment aimed at providing telephone quality natural speech at 4.8 kbps. The work has resulted in two alternative techniques which achieve reasonably good communications quality at 4.8 kbps while tolerating vehicle noise and rather severe channel impairments. The algorithms are embodied in a compact self-contained prototype consisting of two AT and T 32-bit floating-point DSP32 digital signal processors (DSP). A Motorola 68HC11 microcomputer chip serves as the board controller and interface handler. On a wirewrapped card, the prototype's circuit footprint amounts to only 200 sq cm, and consumes about 9 watts of power

Unexpected Ionization Structure in Eta Carinae's "Weigelt Knots"

The Weigelt knots, dense slow-moving ejecta near η Carinae, are mysterious in structure as well as in origin. Using spatially dithered spectrograms obtained with the Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS), we have partially resolved the ionization zones of one knot. Contrary to simple models, higher ionization levels occur on the outer side, i.e., farther from the star. They cannot represent a bow shock, and no satisfying explanation is yet available—though we sketch one qualitative possibility. STIS spectrograms provide far more reliable spatial measurements of the Weigelt knots than HST images do, and this technique can also be applied to the knots' proper motion problem. Our spatial measurement accuracy is about 10 mas, corresponding to a projected linear scale of the order of 30 AU, which is appreciably smaller than the size of each Weigelt knot

Towards understanding the root causes of outdoor education incidents

Outdoor education involves the interaction of people with the natural environment, often in challenging situations. Because of this there are often real risks involved that must be suitably managed. Despite efforts at managing these risks, incidents are still occurring during outdoor education experiences that sometimes culminate in serious injury and even death. While in the past these injuries and fatalities would have been considered unfortunate acts of misadventure, new attitudes in society seek to ascribe blame in the wake of an accident and those involved, or their families, seek penalties for those blamed. Recent legislation such as the Health and Safety in Employment Act make these penalties easier to apply, while the recent actions of both the police and officers of the Department of Labour show the willingness of public officials to investigate and prosecute outdoor education providers if accidents occur. The outdoor education sector has been poorly equipped to reply to the public in the wake of serious incidents. There are few if any statistics on incident rates in the outdoor education sector, and there is very little known about the underlying causes of those incidents. To ensure that outdoor education provision can continue into the future such information needs to be available and training programmes developed based on those findings. This research builds a profile of almost 2000 incidents that occurred in the years 1996 - 2000 at 12 of the 25 larger outdoor education centres in New Zealand that were invited to participate. That profile includes calculating accident rates for the group of organisations sampled and compares these to the rates of accidents occurring in outdoor centres in other parts of the world as well as those occurring in other aspects of life in New Zealand. Eighteen of the incidents were chosen that had potential for serious injury, and these were studied for the root causes of the incidents using a Delphi technique involving three panels of outdoor experts. From this investigation, and an in-depth review of literature from the fields of safety management and psychology, I developed a taxonomy of root causes of outdoor education incidents and suggest a new model of how these root causes can interact to result in an incident. Not all of the identified types of error in the taxonomy of root causes could easily be accommodated within the existing frameworks of outdoor decision-making. In order to provide a model that incorporated these error types, theories of cognitive psychology were combined into a new model of outdoor education decision making in hazardous situations. This shows how personality factors, attitudes and other social factors can act to bias decisions and lead to incidents occurring. As a result of this research, an ongoing collection of incident data in the outdoor education sector is advocated, as is the adoption of the taxonomy of root causes and model of an outdoor education incident into training programmes for outdoor instructors. Through these processes it is hoped that risk management practices will be improved, incidents reduced in frequency and severity, and therefore participation of young people in outdoor education programmes for personal development outcomes can continue to be promoted and justified. Suggestions for further research to build the knowledge of the processes leading to incidents in outdoor education activities are made at the end of this thesis

Building new housing in remote Indigenous communities

SOCIAL AND ECONOMIC BENEFITS CAN ACCOMPANY CAPITAL INVESTMENT IN HOUSING AND INFRASTRUCTURE. THESE ARE MORE LIKELY TO BE REALISED WHEN CONTRACTING METHODS FOR HOUSING PROCUREMENT ARE ALIGNED TO COMMUNITY NEEDS. ALLIANCE CONTRACTING, WHERE RISKS ARE SHARED, CAN SUPPORT INNOVATION IN THE PROCUREMENT SYSTEM TO ACHIEVE ADDITIONAL SOCIAL AND ECONOMIC BENEFITS

Bioinspired Silica Offers a Novel, Green, and Biocompatible Alternative to Traditional Drug Delivery Systems

Development of drug delivery systems (DDS) is essential in many cases to remedy the limitations of free drug molecules. Silica has been of great interest as a DDS due to being more robust and versatile than other types of DDS (e.g., liposomes). Using ibuprofen as a model drug, we investigated bioinspired silica (BIS) as a new DDS and compared it to mesoporous silica (MS); the latter has received much attention for drug delivery applications. BIS is synthesized under benign conditions without the use of hazardous chemicals, which enables controllable in situ loading of drugs by carefully designing the DDS formulation conditions. Here, we systematically studied these conditions (e.g., chemistry, concentration, and pH) to understand BIS as a DDS and further achieve high loading and release of ibuprofen. Drug loading into BIS could be enhanced (up to 70%) by increasing the concentration of the bioinspired additive. Increasing the silicate concentration increased the release to 50%. Finally, acidic synthesis conditions could raise loading efficiency to 62% while also increasing the total mass of drug released. By identifying ideal formulation conditions for BIS, we produced a DDS that was able to release fivefold more drug per weight of silica when compared with MCM-41. Biocompatibility of BIS was also investigated, and it was found that, although ∼20% of BIS was able to pass through the gut wall into the bloodstream, it was nonhemolytic (∼2% hemolysis at 500 μg mL–1) when compared to MS (10% hemolysis at the same concentration). Overall, for DDS, it is clear that BIS has several advantages over MS (ease of synthesis, controllability, and lack of hazardous chemicals) as well as being less toxic, making BIS a real potentially viable green alternative to DDS