A hybrid computer program for rapidly solving flowing or static chemical kinetic problems involving many chemical species

A hybrid chemical kinetic computer program was assembled which provides a rapid solution to problems involving flowing or static, chemically reacting, gas mixtures. The computer program uses existing subroutines for problem setup, initialization, and preliminary calculations and incorporates a stiff ordinary differential equation solution technique. A number of check cases were recomputed with the hybrid program and the results were almost identical to those previously obtained. The computational time saving was demonstrated with a propane-oxygen-argon shock tube combustion problem involving 31 chemical species and 64 reactions. Information is presented to enable potential users to prepare an input data deck for the calculation of a problem

Ignition of mixtures of SiH sub 4, CH sub 4, O sub 2, and Ar or N sub 2 behind reflected shock waves

Ignition delay times in mixtures of methane, silane, and oxygen diluted with argon and nitrogen were measured behind reflected shock waves generated in the chemical kinetic shock tube at Langley Research Center. The delay times were inferred from the rapid increase in pressure that occurs at ignition, and the ignition of methane was verified from the emission of infrared radiation from carbon dioxide. Pressures of 1.25 atm and temperatures from 1100 K to 1300 K were generated behind the reflected shocks; these levels are representative of those occurring within a supersonic Ramjet combustor. Expressions for the ignition delay time as a function of temperature were obtained from least squares curve fits to the data for overall equivalence ratios of 0.7 and 1.0. The ignition delay times with argon as the diluent were longer than those with nitrogen as the diluent. The infrared wavelength observations at 4.38 microns for carbon dioxide indicated that silane and methane ignited simultaneously (i.e., within the time resolution of the measurement). A combined chemical kinetic mechanism for mixtures of silane, methane, oxygen, and argon or nitrogen was assembled from one mechanism that accurately predicted the ignition of methane and a second mechanism that accurately predicted silane hydrogen ignition. Comparisons between this combined mechanism and experiment indicated that additional reactions, possibly between silyl and methyl fragments, are needed to develop a good silane methane mechanism

Design and technology GCE AS and A Level subject content

The AS and A level subject content sets out the knowledge, understanding and skills common to all AS and A level specifications in design and technology. It provides the framework within which awarding organisations create the detail of the subject specification. AS and A Level specifications in design and technology must reflect the subject aims and objectives. Aims and objectives Design and technology is an inspiring, rigorous and practical subject. Specifications in design and technology should encourage students to use creativity and imagination when applying iterative design processes to develop and modify designs, and to design and make prototypes/products1 that solve real world problems, considering their own and others’ needs, wants, aspirations and values. Specifications should enable students to identify market needs and opportunities for new products, initiate and develop design solutions, and make and test prototypes/products. Students should acquire subject knowledge in design and technology, including how a product can be developed through the stages of prototyping, realisation and commercial manufacture. Students should take every opportunity to integrate and apply their understanding and knowledge from other subject areas studied during Key Stage 4, with a particular focus on science and mathematics, and those subjects they are studying alongside AS and A level design and technology

Design and technology GCSE subject content

The GCSE subject content sets out the knowledge, understanding, skills and educational outcomes common to all specifications in design and technology. The GCSE specifications in design and technology should enable students to understand and apply iterative design processes through which they explore, create and evaluate a range of outcomes. They should enable students to use creativity and imagination to design and make prototypes1 (together with evidence of modelling to develop and prove product concept and function) that solve real and relevant problems, considering their own and others’ needs, wants and values. GCSE specifications should also provide opportunities for students to apply knowledge from other disciplines, including mathematics, science, art and design, computing and the humanities. Students should acquire subject knowledge in design and technology that builds on key stage 3, incorporating knowledge and understanding of different materials and manufacturing processes in order to design and make, with confidence, prototypes in response to issues, needs, problems and opportunities. Students should learn how to take design risks, helping them to become resourceful, innovative and enterprising citizens. They should develop an awareness of practices from the creative, engineering and manufacturing industries. Through the critique of the outcomes of design and technology activity, both historic and present day, students should develop an understanding of its impact on daily life and the wider world and understand that high-quality design and technology is important to the creativity, culture, sustainability, wealth and well-being of the nation and the global community

The seasonal upwelling cycle along the eastern boundary of the North Atlantic

Merchant ship observations were summarized for one-degree squares along the eastern shore of the Atlantic between 7° and 44°N; monthly averages were prepared for several properties including sea surface temperature and its difference from mid-ocean values, offshore Ekman transport, and surface current...

Analysis of Racked Wood Pallets

A rational analysis procedure for designing wood stringer pallets for use in warehouse storage racks was developed for manufacturers and pallet users and is part of a computerized automatic design and analysis program called the Pallet Design System (PDS). The procedure uses simplified analog models of pallets and matrix structural analysis methods to compute the stress and deflection of critical structural elements. Semi-rigid nail joints are modeled as spring elements. Pallets with 2, 3, 4, or 5 stringers and up to 15 deckboards can be analyzed with a variety of load types including distributed and concentrated loads. The strength and stiffness of experimental pallets were compared to predicted values and showed good agreement