Apollo experience report: Guidance and control systems - Digital autopilot design development

The development of the Apollo digital autopilots (the primary attitude control systems that were used for all phases of the lunar landing mission) is summarized. This report includes design requirements, design constraints, and design philosophy. The development-process functions and the essential information flow paths are identified. Specific problem areas that existed during the development are included. A discussion is also presented on the benefits inherent in mechanizing attitude-controller logic and dynamic compensation in a digital computer

Space shuttle digital flight control system

The space shuttle digital, fly by wire, flight control system presents an interesting challenge in avionics system design. In residence in each of four redundant general purpose computers at lift off are the guidance, navigation, and control algorithms for the entire flight. The mission is divided into several flight segments: first stage ascent, second stage ascent; abort to launch site, abort once around; on orbit operations, entry, terminal area energy management; and approach and landing. The FCS is complicated in that it must perform the functions to fly the shuttle as a boost vehicle, as a spacecraft, as a reentry vehicle, and as a conventional aircraft. The crew is provided with both manual and automatic modes of operations in all flight phases including touchdown and rollout

The southern dust pillars of the Carina Nebula

We present preliminary results from a detailed study towards four previously detected bright mid-infrared sources in the southern part of the Carina Nebula: G287.73--0.92, G287.84--0.82, G287.93--0.99 and G288.07--0.80. All of these sources are located at the heads of giant dust pillars that point towards the nearby massive star cluster, Trumpler 16. It is unclear if these pillars are the prime sites for a new generation of triggered star formation or if instead they are the only remaining parts of the nebula where ongoing star fromation can take place.Comment: 2 pages, to appear in the proceedings of "Hot Star Workshop III: The Earliest Phases of Massive Star Birth" (ed. P.A. Crowther

Isolation and characterisation of the chick orthologue of the Opitz syndrome gene, Mid1, supports a conserved role in vertebrate development

© UBC PressThe X-linked form of Opitz syndrome (OS) is caused by loss of function of the microtubule-associated MID1 protein. The phenotype of OS includes defects along the central body axis, namely hypertelorism, cleft lip and palate, hypospadias and cardiac structural anomalies. Here we describe the isolation and characterisation of full-length cDNA clones representing the chick Mid1 gene and the detailed profile of its expression in stage 7 to 28 chick embryos. Consistent with the remarkable sequence conservation of MID1 between human and chick was the good correlation of the pattern of cMid1 expression with the tissues affected in OS. In stage 10 embryos, transcripts were concentrated in the head mesenchyme which includes migratory neural crest cells. However, the incomplete overlap with a neural crest marker, Sox10, suggests that Mid1 is a marker for somitomeric mesoderm and potentially for a subset of neural crest cells. Consistent with this, cMid1 expression was also detected at later stages in neural crest-derived facial mesenchyme, in the myotome and in the condensing muscle blocks of the limb. Expression of cMid1 was observed in the neural epithelium of the forebrain beginning at stage 7 with increased signal in presumptive rhombomeres 2/3. By stage 15, expression is highest in the diencephalon. Other areas with high expression are certain facial epithelia and the midgut that will give rise to the oesophagus and trachea. These data indicate that Mid1 plays an evolutionarily conserved developmental function in vertebrates that may involve effects on cellular proliferation, tissue interactions and morphogenesis.Joy M. Richman, Katherine K. Fu, Liza L. Cox, Jane P. Sibbons and Timothy C. Co

Vocation or Victimization: An Analysis of Legal Models Addressing Prostitution

This discussion of legal models addressing prostitution evaluates the three predominate models currently implemented worldwide: criminalization, legalization/full decriminalization, and partial decriminalization (also termed the Nordic Model). Specific focus is given to each model’s capacity to maintain nations’ human rights obligations to people in prostitution, specifically the right to free choice of employment, and the right to safe working conditions free of exploitation and coercion. Along with evaluating the origins, structure, strengths, and weaknesses of each, case studies of all three models in practice are incorporated to transition from theoretical to practical evaluation. Each model’s unique design, purported outcomes, and various failures to fulfill certain aspects of the state’s human rights mandates is explicitly discussed with particular attention to the unintended consequences which exacerbate impacts of systemic inequality worldwide

Rolling-contact bearing reference summary

Design and performance of rolling contact bearing

Investigating the intrinsic noise limit of Dayem bridge NanoSQUIDs

NanoSQUIDs made from Nb thin films have been produced with nanometre loop sizes down to 200 nm, using weak-link junctions with dimensions less than 60 nm. These composite (W/Nb) single layer thin film devices, patterned by FIB milling, show extremely good low-noise performance ∼170 nΦ0 at temperatures between 5 and 8.5 K and can operate in rather high magnetic fields (at least up to 1 T). The devices produced so far have a limited operating temperature range, typically only 1–2 K. We have the goal of achieving operation at 4.2 K, to be compatible with the best SQUID series array (SSA) preamplifier available. Using the SSA to readout the nanoSQUIDs provides us with a means of investigating the intrinsic noise of the former. In this paper we report improved white noise levels of these nanoSQUIDs, enabling potential detection of a single electronic spin flip in a 1-Hz bandwidth. At low frequencies the noise performance is already limited by SSA preamplifier noise

Algal culture studies for CELSS

Microalgae are well-suited as a component of a Closed Environmental Life Support System (CELSS), since they can couple the closely related functions of food production and atmospheric regeneration. The objective was to provide a basis for predicting the response of CELSS algal cultures, and thus the food supply and air regeneration system, to changes in the culture parameters. Scenedesmus growth was measured as a function of light intensity, and the spectral dependence of light absorption by the algae as well as algal respiration in the light were determined as a function of cell concentration. These results were used to test and confirm a mathematical model that describes the productivity of an algal culture in terms of the competing processes of photosynthesis and respiration. The relationship of algal productivity to cell concentration was determined at different carbon dioxide concentrations, temperatures, and light intensities. The maximum productivity achieved by an air-grown culture was found to be within 10% of the computed maximum productivity, indicating that CO2 was very efficiently removed from the gas stream by the algal culture. Measurements of biomass productivity as a function of cell concentration at different light intensities indicated that both the productivity and efficiency of light utilization were greater at higher light intensities

Small Energy Scale for Mixed-Valent Uranium Materials

We investigate a two-channel Anderson impurity model with a $5f^1$ magnetic and a $5f^2$ quadrupolar ground doublet, and a $5f^2$ excited triplet. Using the numerical renormalization group method, we find a crossover to a non-Fermi liquid state below a temperature $T^*$ varying as the $5f^2$ triplet-doublet splitting to the 7/2 power. To within numerical accuracy, the non-linear magnetic susceptibility and the $5f^1$ contribution to the linear susceptibility are given by universal one-parameter scaling functions. These results may explain UBe$_{13}$ as mixed valent with a small crossover scale $T^*$.Comment: 4 pages, 3 figures, REVTeX, to appear in Phys. Rev. Let