The use of database management systems (DBMS) and AI to minimize human involvement in the planning of optical navigation pictures for interplanetary space probes is discussed, with application to the Galileo mission. Parameters characterizing the desirability of candidate pictures, and the program generating them, are described. How these parameters automatically build picture records in a database, and the definition of the database structure, are then discussed. The various rules, priorities, and constraints used in selecting pictures are also described. An example is provided of an expert system, written in Prolog, for automatically performing the selection process.
Abstract This paper presents an approach to determining the optimum number of machines, and their operating rates, for each machine center in a serial-flow production system. Computational comparisons are given to solve this problem using dynamic programming and a standard mixed-integer programming package.
Fully reusable launch vehicle concepts being studied for post-Shuttle era transports present major challenges for the structural design of large propellant tankage. The dominant structural elements are internal tankage for both cryogenic and non-cryogenic propellants which must operate in a broad range of thermal environments while meeting requirements for low weight and reusability. Several approaches to integral tank design are discussed and an analysis of a hot structure honeycomb sandwich tank for a circular body vehicle is presented.
Aquaculture will play an increasingly important role in the global seafood supply as fisheries harvests have plateaued. Shrimp are a highly valuable aquaculture commodity which are produced largely for global trade. The Aquaculture Stewardship Council's shrimp certification standard is meant to serve as a market-based tool that rewards the better actors in the industry for improved performance in areas like technical efficiency, social responsibility, and traceability. The goal of this study was to compare production methodology and efficiency of farms currently certified to the ASC shrimp standard to non-certified farms from recent field surveys in the same geographical areas. Certified farms were statistically larger on average (four times larger in Latin America and 10 times larger in Asia). While farms in Asia operate at higher production intensities, no differences were seen due to certification status. No differences were seen in the FCR of farms in Asia, but ASC farms in Latin America had the higher average FCRs than non-certified farms (1.80 vs. 1.33). ASC farms in Asia used drastically less water exchange and were more energy efficient than other farms as well. These findings were used to make recommendations for the ASC standard and certification standards in general, including a greater emphasis on requirements for limits on efficiency-based metrics beyond reporting the outcome of the calculation.
Shrimp are an important and valuable commodity for aquaculture that are widely traded internationally. Widespread antibiotic use has been documented in shrimp farming and is a common source of criticism of aquaculture products. Additionally, previous reports have found some evidence of antibiotic residues in shrimp samples obtained from retail stores in the United States, which is a concern for consumers. To further understand the prevalence of antibiotics in retail shrimp in the United States, shrimp samples obtained from grocery stores across 16 states were analyzed for 74 antibiotic compounds/metabolites at a commercial laboratory. 68 samples were analyzed for a multiclass antibiotic panel which included 66 antibiotics while a subset of 15 samples were analyzed for β-lactam antibiotics, Nitrofurans, and Oxytetracycline. Samples were obtained that were labeled as being from major production countries, including India, Indonesia, Thailand, and Vietnam. No detectable antibiotic residues were found in this survey in any samples. This is contrary to previous findings in frozen shrimp analyzed for antibiotics, which typically report low levels of the prevalence of antibiotics.
The drive towards dry vacuum pumping has occurred across the spectrum of vacuum applications from semiconductor manufacture to industrial processing. This brings with it a need to systematically evaluate and quantify the degree of cleanliness characteristic of any particular pump; currently, there is no universally accepted method to perform this function. A methodology developed for repeatable measurements of pump cleanliness will be discussed. It utilizes residual gas analysis with carefully controlled pump conditions. This facilitates direct comparisons of the degree of cleanliness between pumps of the same and those of different design. Additionally, it allows for the assessment of methods (either in pump design or use) introduced to improve cleanliness.
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