The Relationship of the value of the Dollar, and the Prices of Gold and Oil: A Tale of Asset Risk

This paper investigates the relationship between the value of the dollar and the prices of two commodities, gold and oil. Granger causality is used on monthly data from January of 1970 through July of 2008. The empirical results show that the hypothesis that there is no causal relation between the value of the dollar and the prices of gold and oil is not supported by the evidence. There are causal relations between each of the prices, and there is a negative relation between the value of the dollar and the price of each of the commodities, as predicted by standard economic theory. Also consistent with the predictions of classical economic theory is that there is a positive statistical association between the prices of gold and oil. The implication is that gold and oil represent safe havens from fluctuations in the value of the dollar.Dollar, Gold, Oil, Exchange Rates, Commodity Prices, Granger Causality

Consistent thermodynamic derivative estimates for tabular equations of state

Numerical simulations of compressible fluid flows require an equation of state (EOS) to relate the thermodynamic variables of density, internal energy, temperature, and pressure. A valid EOS must satisfy the thermodynamic conditions of consistency (derivation from a free energy) and stability (positive sound speed squared). When phase transitions are significant, the EOS is complicated and can only be specified in a table. For tabular EOS's such as SESAME from Los Alamos National Laboratory, the consistency and stability conditions take the form of a differential equation relating the derivatives of pressure and energy as functions of temperature and density, along with positivity constraints. Typical software interfaces to such tables based on polynomial or rational interpolants compute derivatives of pressure and energy and may enforce the stability conditions, but do not enforce the consistency condition and its derivatives. We describe a new type of table interface based on a constrained local least squares regression technique. It is applied to several SESAME EOS's showing how the consistency condition can be satisfied to round-off while computing first and second derivatives with demonstrated second-order convergence. An improvement of 14 orders of magnitude over conventional derivatives is demonstrated, although the new method is apparently two orders of magnitude slower, due to the fact that every evaluation requires solving an 11-dimensional nonlinear system.Comment: 29 pages, 9 figures, 16 references, submitted to Phys Rev

Seawater Photovoltaic-Hydrogen Generation

A Seawater Photovoltaic-Hydrogen Generation System is developed with the goal to produce a safe, user friendly, cost effective, and realistically scaled hydrogen generation system using seawater, particularly for remote regions as well as storage alternatives for renewable energy. An iterative design process was implemented within three prototypes, the first primarily focused on proving the concept of electrolysis, the second to create a robust hydrogen generation system resistant to corrosion using forward osmosis, and the third to scale up our system while also aiming for safety, user friendliness, and cost effectiveness. In the final iteration of our project, an integrated three chamber acrylic tank was created using primarily forward osmosis technology, carbon electrodes, and a palladium tank. This system holds seawater in the first chamber, transfers pure water into the second for electrolysis, converts water into oxygen with electrical current from a PV system, then sends the hydrogen into a palladium tank. All three prototypes successfully yielded hydrogen from seawater. With additional improvements to make our design more mechanically robust, efficient, user friendly, and culturally accepted, this system could become a promising system that can be integrated within communities, particularly remote regions

Solving One Dimensional Scalar Conservation Laws by Particle Management

We present a meshfree numerical solver for scalar conservation laws in one space dimension. Points representing the solution are moved according to their characteristic velocities. Particle interaction is resolved by purely local particle management. Since no global remeshing is required, shocks stay sharp and propagate at the correct speed, while rarefaction waves are created where appropriate. The method is TVD, entropy decreasing, exactly conservative, and has no numerical dissipation. Difficulties involving transonic points do not occur, however inflection points of the flux function pose a slight challenge, which can be overcome by a special treatment. Away from shocks the method is second order accurate, while shocks are resolved with first order accuracy. A postprocessing step can recover the second order accuracy. The method is compared to CLAWPACK in test cases and is found to yield an increase in accuracy for comparable resolutions.Comment: 15 pages, 6 figures. Submitted to proceedings of the Fourth International Workshop Meshfree Methods for Partial Differential Equation

The Effect of Mediators' Qualities and Strategies on Mediation Outcomes

La médiation est probablement la question la moins étudiée de tous les moyens de solution des impasses utilisés à la fois dans les secteurs public et privé. Ceci est malheureux puisque la médiation est le mécanisme de règlement des différends auquel on a recours le plus aux États-Unis. La médiation a été étudiée tant par les tenants de l'approche institutionnelle que par ceux de l'approche empirique et ces deux groupes en sont venus à la conclusion que le travail des médiateurs, leur personnalité et les perceptions des parties sont à la base de l'efficacité de ce mécanisme. Mais ceci reste cependant incomplet. Le but du présent article consiste à vérifier l'effet des qualités et des stratégies des médiateurs dans le règlement réussi des impasses. Cette étude se fonde sur une analyse discriminante pour déterminer si les qualités personnelles des médiateurs et les stratégies qu'ils utilisent permettent de prédire le succès de la médiation dans le règlement des impasses dans le secteur public en Iowa. On a tiré les données de questionnaires distribués aux négociateurs patronaux et syndicaux dans 214 situations d'impasse qui se sont produites en Iowa en 1986.Les questions portaient sur divers aspects des négociations, sur l'impasse elle-même et sur le rôle joué par le médiateur assigné à leur dossier. Pour quantifier les données, on a utilisé l'échelle de Likert.Les résultats obtenus confirment les hypothèses selon lesquelles la personnalité du médiateur et sa façon d'agir permettent de prédire l'issue de la médiation. De plus, plusieurs tactiques et qualités personnelles jugées significatives sont importantes pour les deux parties. Trois des six caractéristiques significatives sont les mêmes pour les syndicats et les employeurs, soit (1) leur habileté à 'parler' le langage des parties, (2) la ténacité et la maîtrise de soi et (3) l'impartialité et la franchise. Huit des quatorze tactiques ou stratégies du médiateur considérées comme significatives sont également communes aux deux parties. La plus importante d'entre elles consiste dans la formulation de propositions de nature à éviter une apparence de défaite d'une partie ou de l'autre.Ces résultats, lorsqu'on les considère à la lumière d'un certain nombre d'autres études récentes, permettent de voir que la personnalité des médiateurs peut être une des conditions préalables pour que leurs stratégies deviennent efficaces dans la solution des impasses. La constance avec laquelle la personnalité des médiateurs est perçue par les syndicats et par les employeurs ainsi que l'importance relative de certaines de leurs stratégies supportent l'hypothèse voulant que les théories sur les comportements dans la médiation sont exactes; cependant, ces théories doivent faire l'objet de recherches plus poussées.Il est clair que les stratégies et la personnalité des médiateurs permettent de prédire l'issue de la médiation, mais il faut en savoir plus sur la façon dont elles en influencent les résultats. Les conclusions de cette étude confirment que la perception qu'ont les parties du médiateur est un facteur déterminant dans l'aide que la médiation peut apporter dans la solution des impasses.This study utilizes discriminant analysis to determine if the characteristics of mediators and the strategies they employ predict the success of mediation in resolving impasses in the public sector in lowa. The data were obtained from questionnaires administered to management and union negotiators in the 214 impasses reported in lowa during 1986. Mediators' characteristics and the strategies they employ are found to predict the success of mediation for both management and union negotiators in lowa during 1986

Progress in smooth particle hydrodynamics

Smooth Particle Hydrodynamics (SPH) is a meshless, Lagrangian numerical method for hydrodynamics calculations where calculational elements are fuzzy particles which move according to the hydrodynamic equations of motion. Each particle carries local values of density, temperature, pressure and other hydrodynamic parameters. A major advantage of SPH is that it is meshless, thus large deformation calculations can be easily done with no connectivity complications. Interface positions are known and there are no problems with advecting quantities through a mesh that typical Eulerian codes have. These underlying SPH features make fracture physics easy and natural and in fact, much of the applications work revolves around simulating fracture. Debris particles from impacts can be easily transported across large voids with SPH. While SPH has considerable promise, there are some problems inherent in the technique that have so far limited its usefulness. The most serious problem is the well known instability in tension leading to particle clumping and numerical fracture. Another problem is that the SPH interpolation is only correct when particles are uniformly spaced a half particle apart leading to incorrect strain rates, accelerations and other quantities for general particle distributions. SPH calculations are also sensitive to particle locations. The standard artificial viscosity treatment in SPH leads to spurious viscosity in shear flows. This paper will demonstrate solutions for these problems that they and others have been developing. The most promising is to replace the SPH interpolant with the moving least squares (MLS) interpolant invented by Lancaster and Salkauskas in 1981. SPH and MLS are closely related with MLS being essentially SPH with corrected particle volumes. When formulated correctly, JLS is conservative, stable in both compression and tension, does not have the SPH boundary problems and is not sensitive to particle placement. The other approach to solving SPH problems, pioneered by Randles and Libersky, is to use a different SPH equation and to renormalize the kernel gradient sums. Finally the authors present results using the SPH statistical fracture model (SPHSFM). It has been applied to a series of ball on plate impacts performed by Grady and Kipp. A description of the model and comparison with the experiments will be given

Integrated Radiation Transport and Nuclear Fuel Performance for Assembly-Level Simulations

The Advanced Multi-Physics (AMP) Nuclear Fuel Performance code (AMPFuel) is focused on predicting the temperature and strain within a nuclear fuel assembly to evaluate the performance and safety of existing and advanced nuclear fuel bundles within existing and advanced nuclear reactors. AMPFuel was extended to include an integrated nuclear fuel assembly capability for (one-way) coupled radiation transport and nuclear fuel assembly thermo-mechanics. This capability is the initial step toward incorporating an improved predictive nuclear fuel assembly modeling capability to accurately account for source-terms and boundary conditions of traditional (single-pin) nuclear fuel performance simulation, such as the neutron flux distribution, coolant conditions, and assembly mechanical stresses. A novel scheme is introduced for transferring the power distribution from the Scale/Denovo (Denovo) radiation transport code (structured, Cartesian mesh with smeared materials within each cell) to AMPFuel (unstructured, hexagonal mesh with a single material within each cell), allowing the use of a relatively coarse spatial mesh (10 million elements) for the radiation transport and a fine spatial mesh (3.3 billion elements) for thermo-mechanics with very little loss of accuracy. In addition, a new nuclear fuel-specific preconditioner was developed to account for the high aspect ratio of each fuel pin (12 feet axially, but 1 4 inches in diameter) with many individual fuel regions (pellets). With this novel capability, AMPFuel was used to model an entire 17 17 pressurized water reactor fuel assembly with many of the features resolved in three dimensions (for thermo-mechanics and/or neutronics), including the fuel, gap, and cladding of each of the 264 fuel pins; the 25 guide tubes; the top and bottom structural regions; and the upper and lower (neutron) reflector regions. The final, full assembly calculation was executed on Jaguar using 40,000 cores in under 10 hours to model over 162 billion degrees of freedom for 10 loading steps. The single radiation transport calculation required about 50% of the time required to solve the thermo-mechanics with a single loading step, which demonstrates that it is feasible to incorporate, in a single code, a high-fidelity radiation transport capability with a high-fidelity nuclear fuel thermo-mechanics capability and anticipate acceptable computational requirements. The results of the full assembly simulation clearly show the axial, radial, and azimuthal variation of the neutron flux, power, temperature, and deformation of the assembly, highlighting behavior that is neglected in traditional axisymmetric fuel performance codes that do not account for assembly features, such as guide tubes and control rods

Thermochemistry of Alane Complexes for Hydrogen Storage: A Theoretical and Experimental Comparison

Knowledge of the relative stabilities of alane (AlH3) complexes with electron donors is essential for identifying hydrogen storage materials for vehicular applications that can be regenerated by off-board methods; however, almost no thermodynamic data are available to make this assessment. To fill this gap, we employed the G4(MP2) method to determine heats of formation, entropies, and Gibbs free energies of formation for thirty-eight alane complexes with NH3-nRn (R = Me, Et; n = 0-3), pyridine, pyrazine, triethylenediamine (TEDA), quinuclidine, OH2-nRn (R = Me, Et; n = 0-2), dioxane, and tetrahydrofuran (THF). Monomer, bis, and selected dimer complex geometries were considered. Using these data, we computed the thermodynamics of the key formation and dehydrogenation reactions that would occur during hydrogen delivery and alane regeneration, from which trends in complex stability were identified. These predictions were tested by synthesizing six amine-alane complexes involving trimethylamine, triethylamine, dimethylethylamine, TEDA, quinuclidine, and hexamine, and obtaining upper limits of delta G for their formation from metallic aluminum. Combining these computational and experimental results, we establish a criterion for complex stability relevant to hydrogen storage that can be used to assess potential ligands prior to attempting synthesis of the alane complex. Based on this, we conclude that only a subset of the tertiary amine complexes considered and none of the ether complexes can be successfully formed by direct reaction with aluminum and regenerated in an alane-based hydrogen storage system.Comment: Accepted by the Journal of Physical Chemistry