Morphing Wings Using Macro Fiber Composites

Macro Fiber Composites (MFC) are smart materials that have one or more properties that can be altered by an external stimulus such as magnetic and electric fields, temperature and pH, in order to meet specific requirements or conditions. Today, smart materials are used in a variety of applications in the aerospace industry, locomotives, and in the medical field to generate better performance for its devices. The objective of this paper is to describe an experiment on morphing a wing using MFCs. The materials needed to achieve this project are illustrated in the experimental setup of this paper. Additionally, the author expects to be able to morph the wing of the aircraft and compare its acquired data to that of a general aircraft to determine which one has the best performance

Determination of Equilibrium Constants for the Reaction between Acetone and HO_2 Using Infrared Kinetic Spectroscopy

The reaction between the hydroperoxy radical, HO_2, and acetone may play an important role in acetone removal and the budget of HO_x radicals in the upper troposphere. We measured the equilibrium constants of this reaction over the temperature range of 215–272 K at an overall pressure of 100 Torr using a flow tube apparatus and laser flash photolysis to produce HO_2. The HO_2 concentration was monitored as a function of time by near-IR diode laser wavelength modulation spectroscopy. The resulting [HO_2] decay curves in the presence of acetone are characterized by an immediate decrease in initial [HO_2] followed by subsequent decay. These curves are interpreted as a rapid (<100 μs) equilibrium reaction between acetone and the HO_2 radical that occurs on time scales faster than the time resolution of the apparatus, followed by subsequent reactions. This separation of time scales between the initial equilibrium and ensuing reactions enabled the determination of the equilibrium constant with values ranging from 4.0 × 10^(–16) to 7.7 × 10^(–1)8 cm^3 molecule^(–1) for T = 215–272 K. Thermodynamic parameters for the reaction determined from a second-law fit of our van’t Hoff plot were Δ_(r)H°_(245) = −35.4 ± 2.0 kJ mol^(–1) and Δ_(r)S°_(245) = −88.2 ± 8.5 J mol^(–1) K^(–1). Recent ab initio calculations predict that the reaction proceeds through a prereactive hydrogen-bonded molecular complex (HO_2–acetone) with subsequent isomerization to a hydroxy–peroxy radical, 2-hydroxyisopropylperoxy (2-HIPP). The calculations differ greatly in the energetics of the complex and the peroxy radical, as well as the transition state for isomerization, leading to significant differences in their predictions of the extent of this reaction at tropospheric temperatures. The current results are consistent with equilibrium formation of the hydrogen-bonded molecular complex on a short time scale (100 μs). Formation of the hydrogen-bonded complex will have a negligible impact on the atmosphere. However, the complex could subsequently isomerize to form the 2-HIPP radical on longer time scales. Further experimental studies are needed to assess the ultimate impact of the reaction of HO_2 and acetone on the atmosphere

A Density Functional Study of Atomic Hydrogen and Oxygen Chemisorption on the Relaxed (0001) Surface of Double Hexagonal Close Packed Americium

Ab initio total energy calculations within the framework of density functional theory have been performed for atomic hydrogen and oxygen chemisorption on the (0001) surface of double hexagonal packed americium using a full-potential all-electron linearized augmented plane wave plus local orbitals method. Chemisorption energies were optimized with respect to the distance of the adatom from the relaxed surface for three adsorption sites, namely top, bridge, and hollow hcp sites, the adlayer structure corresponding to coverage of a 0.25 monolayer in all cases. Chemisorption energies were computed at the scalar-relativistic level (no spin-orbit coupling NSOC) and at the fully relativistic level (with spin-orbit coupling SOC). The two-fold bridge adsorption site was found to be the most stable site for O at both the NSOC and SOC theoretical levels with chemisorption energies of 8.204 eV and 8.368 eV respectively, while the three-fold hollow hcp adsorption site was found to be the most stable site for H with chemisorption energies of 3.136 eV at the NSOC level and 3.217 eV at the SOC level. The respective distances of the H and O adatoms from the surface were found to be 1.196 Ang. and 1.164 Ang. Overall our calculations indicate that chemisorption energies in cases with SOC are slightly more stable than the cases with NSOC in the 0.049-0.238 eV range. The work functions and net magnetic moments respectively increased and decreased in all cases compared with the corresponding quantities of bare dhcp Am (0001) surface. The partial charges inside the muffin-tins, difference charge density distributions, and the local density of states have been used to analyze the Am-adatom bond interactions in detail. The implications of chemisorption on Am 5f electron localization-delocalization are also discussed.Comment: 9 Tables, 5 figure

Perancangan Sistem Informasi Manajemen Produksi Dengan Pemanfaatan Pendekatan Fuzzy Logic Untuk Penentuan Jumlah Produksi

Ketidak pastian permintaan produk menjadikan kebutuhan informasi yang cepat dan tepat menjadi syarat mutlak yang tersedia secara up to date sebagai pertimbangan dalam pengambilan keputusan jumlah produksi. Saat ini, pengelolaan permintaan produk keripik singkong di UD Lumba-lumba masih dilakukan secara manual. Pencatatan yang dilakukan secara manual dirasa kurang efisien, sebab dibutuhkan ketelitian dan kedisiplinan pegawai dalam melakukan update informasi. Selain itu, dalam pengambilan keputusan jumlah produksi di UD Lumba-lumba juga masih menggunakan keputusan subyektif dari penanggung jawab produksi. Oleh karena itu, perlu adanya perancangan sistem informasi manajemen produksi dengan pemanfaatan sistem database sebagai pengelola data serta penerapan pendekatan fuzzy logic untuk membantu dalam pengambilan keputusan jumlah produksi. Sistem informasi manajemen produksi dirancang untuk mengotomasi sistem yang telah ada di UD Lumba-lumba agar lebih baik. Perancangan prototype sistem informasi manajemen produksi, dilakukan dengan membangun aplikasi berbasis web menggunakan bahasa pemrograman PHP dan database MySQL. Berdasarkan uji prototype yang dilakukan, sistem informasi manajemen produksi mampu memberikan informasi-informasi yang berkaitan dengan permintaan produk, persediaan dan memberikan rekomendasi terhadap jumlah produksi. Dengan pemanfaatan sistem informasi dan database, pengelolaan data serta penyediaan informasi menjadi lebih baik, cepat dan efisien

Density functional study of the actinide nitrides

The full potential all electron linearized augmented plane wave plus local orbitals (FP-LAPW + lo) method, as implemented in the suite of software WIEN2K, has been used to systematically investigate the structural, electronic, and magnetic properties of the actinide compounds AnN (An = Ac, Th, Pa, U, Np, Pu, Am). The theoretical formalism used is the generalized gradient approximation to density functional theory (GGA-DFT) with the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional. Each compound has been studied at six levels of theory: non-magnetic (NM), non-magnetic with spin-orbit coupling (NM+SOC), ferromagnetic (FM), ferromagnetic with spin-orbit coupling (FM+SOC), anti-ferromagnetic (AFM), and anti-ferromagnetic with spin-orbit coupling (AFM+SOC). The structural parameters, bulk moduli, densities of states, and charge distributions have been computed and compared to available experimental data and other theoretical calculations published in the literature. The total energy calculations indicate that the lowest energy structures of AcN, ThN, and PaN are degenerate at the NM+SOC, FM+SOC, and AFM+SOC levels of theory with vanishing total magnetic moments in the FM+SOC and AFM+SOC cases, making the ground states essentially non-magnetic with spin-orbit interaction. The ground states of UN, NpN, PuN, and AmN are found to be FM+SOC at the level of theory used in the present computations. The nature of the interactions between the actinide metals and nitrogen atom, and the implications on 5f electron delocalization and localization are discussed in detail.Comment: 5 tables, 12 figure

Computational Study of Turbulent-Laminar Patterns in Couette Flow

Turbulent-laminar patterns near transition are simulated in plane Couette flow using an extension of the minimal flow unit methodology. Computational domains are of minimal size in two directions but large in the third. The long direction can be tilted at any prescribed angle to the streamwise direction. Three types of patterned states are found and studied: periodic, localized, and intermittent. These correspond closely to observations in large aspect ratio experiments.Comment: 4 pages, 5 figure

Adsorption and dissociation of molecular oxygen on the (0001) surface of double hexagonal close packed americium

In our continuing attempts to understand theoretically various surface properties such as corrosion and potential catalytic activity of actinide surfaces in the presence of environmental gases, we report here the first ab initio study of molecular adsorption on the double hexagonal packed (dhcp) americium (0001) surface. Dissociative adsorption is found to be energetically more favorable compared to molecular adsorption. The most stable configuration corresponds to a horizontal approach molecular dissociation with the oxygen atoms occupying neighboring h3 sites, with chemisorption energies at the NSOC and SOC theoretical levels being 9.395 eV and 9.886 eV, respectively. The corresponding distances of the oxygen molecule from the surface and oxygen-oxygen distance were found to be 0.953 Ang. and 3.731 Ang., respectively. Overall our calculations indicate that chemisorption energies in cases with SOC are slightly more stable than the cases with NSOC in the 0.089-0.493 eV range. The work functions and net magnetic moments respectively increased and decreased in all cases compared with the corresponding quantities of the bare dhcp Am (0001) surface. The adsorbate-substrate interactions have been analyzed in detail using the partial charges inside the muffin-tin spheres, difference charge density distributions, and the local density of states. The effects, if any, of chemisorption on the Am 5f electron localization-delocalization characteristics in the vicinity of the Fermi level are also discussed.Comment: 6 tables, 10 figure

To what extent can dynamical models describe statistical features of turbulent flows?

Statistical features of "bursty" behaviour in charged and neutral fluid turbulence, are compared to statistics of intermittent events in a GOY shell model, and avalanches in different models of Self Organized Criticality (SOC). It is found that inter-burst times show a power law distribution for turbulent samples and for the shell model, a property which is shared only in a particular case of the running sandpile model. The breakdown of self-similarity generated by isolated events observed in the turbulent samples, is well reproduced by the shell model, while it is absent in all SOC models considered. On this base, we conclude that SOC models are not adequate to mimic fluid turbulence, while the GOY shell model constitutes a better candidate to describe the gross features of turbulence.Comment: 14 pages, 4 figures, in press on Europhys. Lett. (may 2002