Maximum Height to Width Ratio of Freestanding Structures Built Using Ultrasonic Consolidation

Ultrasonic consolidation (UC) is a process whereby metal foils can be metallurgically bonded at or near room temperature. The UC process works by inducing high-speed differential motion (~20kHz) between a newly deposited layer and a substrate (which consists of a base plate and any previously deposited layers of material). This differential motion causes plastic deformation at the interface, which breaks up surface oxides and deforms surface asperities, bringing clean metal surfaces into intimate contact, where bonding occurs. If the substrate is not stiff enough to resist deflection during ultrasonic excitation of newly deposited layers, then it deflects along with the newly deposited layer, resulting in no differential motion and lack of bonding. Geometric issues which control substrate stiffness and deflection were investigated at Utah State University by building a number of free-standing rib structures with varying dimensions and orientations. Each structure was built to a height where lack of bonding between the previously deposited layers and the newly deposited layer caused the building process to fail, a height to width ratio (H/W) of approximately 1:1. The parts were then cut, polished, and viewed under a microscope. An ANSYS model was created to investigate analytically the cause of this failure. It appears build failure is due to excessive deflection of the ribs around a 1:1 H/W, resulting in insufficient differential motion and deformation to achieve bonding. Preliminary results show, when the H/W reaches 1:1, the von Mises stress is found to be tensile along portions of the bonding interface, which eliminates the compressive frictional forces necessary for plastic deformation and formation of a metallurgical bond. These tensile stresses are shown to be concentrated at regions near the edges of the newly deposited foil layer.Mechanical Engineerin

Thermodynamics and area in Minkowski space: Heat capacity of entanglement

Tracing over the degrees of freedom inside (or outside) a sub-volume V of Minkowski space in a given quantum state |psi>, results in a statistical ensemble described by a density matrix rho. This enables one to relate quantum fluctuations in V when in the state |psi>, to statistical fluctuations in the ensemble described by rho. These fluctuations scale linearly with the surface area of V. If V is half of space, then rho is the density matrix of a canonical ensemble in Rindler space. This enables us to `derive' area scaling of thermodynamic quantities in Rindler space from area scaling of quantum fluctuations in half of Minkowski space. When considering shapes other than half of Minkowski space, even though area scaling persists, rho does not have an interpretation as a density matrix of a canonical ensemble in a curved, or geometrically non-trivial, background.Comment: 17 page

A Framework for Managing Flexibility in the Information Systems Function

Competitive pressures are forcing organizations to be agile and flexible. Response to changing environmental conditions is an important factor in determining corporate performance. Organizational flexibility is in turn closely related to the management of information systems. Organizations with flexible IS functions are in a position to be more responsive and take advantage of changes in both their internal and external environments. Conversely, inflexibility in IS can inhibit organizational growth and put a company in a competitive disadvantage. This paper argues that IS flexibility is a multidimensional concept. Grounded theory methodology is used to empirically derive a taxonomy of several types of flexibility and flexibility management strategies

Enhancing multi-scale Mekong water governance

The CPWF Project PN50 “Enhancing multi-scale water governance” was a flagship activity of the Mekong Program on Water, Environment Resilience (M-POWER). The goal of helping improve livelihood security, human and ecosystem health in the Mekong Region through democratizing water governance was pursued through critical research and direct engagement with stakeholders involved in managing floods, irrigation, hydropower, watersheds, fisheries and urban water works at various scales. We identified commons governance problems and suggested ways that some can be addressed. Often, for example, there are needs to: strengthen local representation, improve the quality of deliberative processes, enhance the interplay between institutions at different levels, and build capacities to handle uncertainties and adapt to changes in flow regimes

Interface Microstructures and Bond Formation in Ultrasonic Consolidation

The quality of ultrasonically consolidated parts critically depends on the bond quality between individual metal foils. This necessitates a detailed understanding of interface microstructures and ultrasonic bonding mechanism. There is a lack of information on interface microstructures in ultrasonically consolidated parts as well as a lack of consensus on the mechanism of metal ultrasonic welding, especially on matters such as plastic deformation and recrystallization. In the current work, interface microstructures of an ultrasonically consolidated multi-material Al 3003-Ni 201 sample were analyzed in detail using optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, and orientation imaging microscopy. Based on the results of microstructural studies, the mechanism of metal ultrasonic welding has been discussed. The reasons for formation of defects/unbonded regions in ultrasonically consolidated parts have also been identified and discussedMechanical Engineerin

Tuning magnetic frustration on the diamond lattice of the A-site magnetic spinels CoAl2−x_{2-x}Gax_xO4_4: Lattice expansion and site disorder

The spinels CoB$_2$O$_4$ with magnetic Co$^{2+}$ ions on the diamond lattice A site can be frustrated because of competing near-neighbor ($J_1$) and next-near neighbor ($J_2$) interactions. Here we describe attempts to tune the relative strengths of these interactions by substitution on the non-magnetic B-site. The system we employ is CoAl$_{2-x}$Ga$_x$O$_4$, where Al is systematically replaced by the larger Ga, ostensibly on the B site. As expected, Ga substitution expands the lattice, resulting in Co atoms on the A-site being pushed further from one other and thereby weakening magnetic interactions. In addition, Ga distributes between the B and the A site in a concentration dependent manner displacing an increasing amount of Co from the A site with increasing $x$. This increased inversion, which is confirmed by neutron diffraction studies carried out at room temperature, affects magnetic ordering very significantly, and changes the nature of the ground state. Modeling of the magnetic coupling illustrates the complexity that arises from the cation site disorder.Comment: 9 pages, 10 figure

Molluscicidal effect of biogenic silica and botanical pesticides for the control of Achatina fulica (giant African land snail) and Laevicaulis alte (garden slug)

The molluscicidal effect of silica synthesized from rice husk ash (RHA) on snails (Achatina fulica Bowdich) and slugs (Laevicaulis alte Férussac) was assessed under laboratory conditions. The silica particles derived from RHA were also coated with leaf extracts (botanical pesticides): Azadirachta indica A. Juss, Pongamia pinnata (L.), Nicotiana tabacum (L.), and Calotropis procera (L.). The silica coated with plant extracts and the uncoated silica were applied to the molluscs in dust or slurry form. Inactivation, mortality, and body fluid loss in A. fulica and L. alte were observed over 24 h and recorded. The body fluid losses were 25%–42% for snails and 37%–62% for slugs that had been dusted with silica. During the experiment it was also noted that as the concentration of silica increased (0.15, 0.20, and 0.25 g), the time required for inactivation and mortality was reduced. The dust application was more effective than the slurry. The lower concentration of silica in the slurry (0.05 and 0.10 g) did not have any significant effect on A. fulica or L. alte. For A. fulica the biopesticide-coated silica particles were more effective when coated with neem, followed by tobacco and karanj; for L. alte, the particles were most effective when coated with tobacco, followed by neem and karanj. The plant extract (liquid as well as dry powder) without silica showed no molluscicidal effect on A. fulica and L. alte, except for some temporary inactivation, particularly with tobacco extract. The application of common salt, a practice often used by farmers, was also tested. It was observed that the effects of common salt on A. fulica and L. alte were less significant than those of silica coated with botanical pesticides.

Line Intensities and Molecular Opacities of the FeH F4Δi−X4ΔiF^4\Delta_i-X^4\Delta_i Transition

We calculate new line lists and opacities for the $F^4\Delta_i-X^4\Delta_i$ transition of FeH. The 0-0 band of this transition is responsible for the Wing-Ford band seen in M-type stars, sunspots and brown dwarfs. The new Einstein A values for each line are based on a high level ab initio calculation of the electronic transition dipole moment. The necessary rotational line strength factors (H\"onl-London factors) are derived for both the Hund's case (a) and (b) coupling limits. A new set of spectroscopic constants were derived from the existing FeH term values for v=0, 1 and 2 levels of the $X$ and $F$ states. Using these constants extrapolated term values were generated for v=3 and 4 and for $J$ values up to 50.5. The line lists (including Einstein A values) for the 25 vibrational bands with v$\leq$4 were generated using a merged list of experimental and extrapolated term values. The FeH line lists were use to compute the molecular opacities for a range of temperatures and pressures encountered in L and M dwarf atmospheres. Good agreement was found between the computed and observed spectral energy distribution of the L5 dwarf 2MASS-1507.Comment: 52 pages, 3 figures, many tables, accepted for publication in the Astrophysical Journal Supplement