Simulation and experimental results of an unmanned towed system

This report investigates the flight dynamics of a small-scale (2 ft) towed system using a quadcopter and actively controlled payload. A towed system includes a main driver to propel the system forward connected to a payload via a tether. The towed system here is unique, and in that the driver is a scratch built quadcopter while the payload is also a scratch built actively controlled aircraft. The payload is designed to carry a small instrument that must be sufficiently far away from all interferences created by a quadcopter. A fully non-linear full state model is created and utilized to reveal that oscillations in the payload are decreased with the introduction of a PD controller on the payload. An experimental setup is built to validate simulation results. Experiments show that an actively controlled payload can decrease the attitude oscillations of the payload.

The importance of non-photon noise in astronomical spectropolarimetry

Stellar spectropolarimetry has become an extremely popular technique during the last decade or two, and has led to major advances in the studies of stellar magnetic fields. Many important discoveries have been made thanks to ultra-precise measurements of very small polarimetric signals, which require very stable instruments and special observing strategies. The so called beam-swapping technique is a well-known polarimetric technique capable of suppressing many spurious signals due to various instrumental effects. However, when one is interested in ultra-high signal-to-noise ratio measurements, observers start to hit various limitations introduced by the instrument, by the atmosphere, and even by the software for data-reduction. These limitations cannot be overcome by the observing strategies, and sources of errors other than photon-noise must be taken into account. Here we discuss the advantages of the beam-swapping technique, and the impact of small instrument and atmospheric instabilities, and how these issues offer an explanation for the origin of the apparently significant observed polarisation signals produced by effects other than those intrinsic to the observed target.

New Instrument for Robotic-Enhanced Skeletonized Internal Thoracic Artery Harvesting: Triangular Hook

Objective The introduction of robotic surgery has generated innovations in minimally invasive coronary surgery, including instrumentation. We have developed a small instrument, named by us the Triangular Hook, that expedites robotic skeletonization of the internal thoracic artery and makes the procedure safer. Methods Bilateral skeletonized internal thoracic artery harvesting was performed in four dogs (weight, 22 to 36 kg), using the da Vinci surgical system (Intuitive Surgical, Inc, Sunnyvale, CA). One internal thoracic artery was harvested with the Triangular Hook; the other was harvested without it. Harvesting time was measured for each form of harvesting, with the data being reported as mean ± SD. Results All eight internal thoracic arteries were harvested successfully; they were patent at the end of harvesting. Significantly less time was required for the Triangular Hook (41.5 ± 2.8 minutes) than for harvesting without it (47.5 ± 3.9 minutes; P = 0.02). Conclusions The Triangular Hook is practicable and safe in robotic skeletonization of the internal thoracic artery.

The United Nations Basic Space Science Initiative for IHY 2007

The United Nations Office for Outer Space Affairs and the International Heliophysical Year (IHY) community have joined hands to deploy arrays of small, inexpensive instruments such as magnetometers, radio telescopes, GPS receivers, all-sky cameras, and particle detectors around the world to provide global measurements of ionospheric, magnetospheric and heliospheric phenomena. The small instrument programme is envisioned as a partnership between instrument providers, and instrument hosts in developing countries as one of United Nations Basic Space Science (UNBSS) activity. The lead scientist will provide the instruments (or fabrication plans for instruments) in the array; the host country will provide manpower, facilities, and operational support to obtain data with the instrument, located typically at a local university. This paper provides an overview of the IHY/UNBSS programme, its achievements and future plans.

Contact and elastohydrodynamic analysis of worm gears Part 2: Results

The paper presents the results of modelling the contact and elastohydrodynamic lubrication (EHL) effects between the teeth of worm gears. A number of different practical worm gear designs have been studied covering a wide range of sizes and potential applications, from small instrument drives to high power units. All the designs are of the popular ZI type, in which the worm is an involute helicoid, with deliberate mismatch of tooth conformity in order to avoid damaging edge contact. The results cover loaded tooth contact analysis (‘loaded TCA’) under dry conditions, predicted film-generating behaviour with lubrication, surface and oil film temperatures, and calculated values of friction and transmission efficiency. It is demonstrated that regions of poor film formation may be predicted in a qualitative way on the basis of loaded TCA together with consideration of the kinematics of entrainment at the contacts.

Microarcsec Astrometry: The Gaia Mission

The Hipparcos mission demonstrated the efficiency of space astrometry (in terms of number of objects, accuracy, and uniformity of results) and the fact that a relatively small instrument can have a very large scientific potential in the area of astrometry. However, Hipparcos could probe less than 0.1 per cent of the volume of the Galaxy by direct distance measurements. Using a larger instrument and more efficient detectors, it is now technically feasible to increase the efficiency of a space astrometry mission by several orders of magnitude, thus encompassing a large part of the Galaxy within its horizon for accurate determination of parallaxes and transverse velocities. Such a mission will have immediate and profound impact in the areas of the physics and evolution of individual stars and of the Galaxy as a whole.

Comment on Transcutaneous Bilirubin Device of Yamanouchi

Yamanouchi et al (Pediatrics 65:195, 1980) have reported a new simple noninvasive method for the transcutaneous measurement of bilirubin levels in newborn infants using a small instrument which measures the color intensity of the skin. By using that method, we have estimated the number of serum bilirubin measurements on capillary samples which could be avoided in full-term infants without clinical problems other than jaundice. In the last 12 months 2,555 newborns weighing 2,501 to 4,000 gm were admitted to our nursery; bilirubinemia was determined at least once in 2,011 (78.7%) of them, giving a total number of determinations of 11,301.