What has NMR taught us about stripes and inhomogeneity?

The purpose of this brief invited paper is to summarize what we have (not) learned from NMR on stripes and inhomogeneity in La{2-x}Sr{x}CuO{4}. We explain that the reality is far more complicated than generally accepted.Comment: Accepted for publication in the Proceedings of the LT-23 Conference (invited

Saturation-Dependence of Dispersion in Porous Media

In this study, we develop a saturation-dependent treatment of dispersion in porous media using concepts from critical path analysis, cluster statistics of percolation, and fractal scaling of percolation clusters. We calculate spatial solute distributions as a function of time and calculate arrival time distributions as a function of system size. Our previous results correctly predict the range of observed dispersivity values over ten orders of magnitude in experimental length scale, but that theory contains no explicit dependence on porosity or relative saturation. This omission complicates comparisons with experimental results for dispersion, which are often conducted at saturation less than 1. We now make specific comparisons of our predictions for the arrival time distribution with experiments on a single column over a range of saturations. This comparison suggests that the most important predictor of such distributions as a function of saturation is not the value of the saturation per se, but the applicability of either random or invasion percolation models, depending on experimental conditions

Predicting Water Cycle Characteristics from Percolation Theory and Observational Data.

The fate of water and water-soluble toxic wastes in the subsurface is of high importance for many scientific and practical applications. Although solute transport is proportional to water flow rates, theoretical and experimental studies show that heavy-tailed (power-law) solute transport distribution can cause chemical transport retardation, prolonging clean-up time-scales greatly. However, no consensus exists as to the physical basis of such transport laws. In percolation theory, the scaling behavior of such transport rarely relates to specific medium characteristics, but strongly to the dimensionality of the connectivity of the flow paths (for example, two- or three-dimensional, as in fractured-porous media or heterogeneous sediments), as well as to the saturation characteristics (i.e., wetting, drying, and entrapped air). In accordance with the proposed relevance of percolation models of solute transport to environmental clean-up, these predictions also prove relevant to transport-limited chemical weathering and soil formation, where the heavy-tailed distributions slow chemical weathering over time. The predictions of percolation theory have been tested in laboratory and field experiments on reactive solute transport, chemical weathering, and soil formation and found accurate. Recently, this theoretical framework has also been applied to the water partitioning at the Earth's surface between evapotranspiration, ET, and run-off, Q, known as the water balance. A well-known phenomenological model by Budyko addressed the relationship between the ratio of the actual evapotranspiration (ET) and precipitation, ET/P, versus the aridity index, ET0/P, with P being the precipitation and ET0 being the potential evapotranspiration. Existing work was able to predict the global fractions of P represented by Q and ET through an optimization of plant productivity, in which downward water fluxes affect soil depth, and upward fluxes plant growth. In the present work, based likewise on the concepts of percolation theory, we extend Budyko's model, and address the partitioning of run-off Q into its surface and subsurface components, as well as the contribution of interception to ET. Using various published data sources on the magnitudes of interception and information regarding the partitioning of Q, we address the variability in ET resulting from these processes. The global success of this prediction demonstrated here provides additional support for the universal applicability of percolation theory for solute transport as well as guidance in predicting the component of subsurface run-off, important for predicting natural flow rates through contaminated aquifers

CORGI: Compute Oriented Recumbent Generation Infrastructure

Creating a bicycle with a rideable geometry is more complicated than it may appear, with today’s mainstay designs having evolved through years of iteration. This slow evolution coupled with the bicycle’s intricate mechanical system has lead most builders to base their new geometries off of previous work rather than expand into new design spaces. This crutch can lead to slow bicycle iteration rates, often causing bicycles to all look about the same. To combat this, several bicycle design models have been created over the years, with each attempting to define a bicycle’s handling characteristics given its physical geometry. However, these models often analyze a single bicycle at a time, and as such, using them in an iterative design process can be cumbersome. This work seeks to improve an existing model used by the Cal Poly Mechanical Engineering department such that it can be used in a proactive, iterative fashion (as opposed to the reactive, single-design paradigm that it currently supports). This is accomplished by expanding the model’s inputs to include more bicycle components as well as differently sized riders. This augmented model is then incorporated into several search platforms ranging from a brute-force implementation to several variants using genetic algorithm concepts. These models allow the designer to specify a bicycle design search space as well as a set of riders upfront, from which the algorithms search out and find strong candidate designs to return to the user. This in turn reduces the overhead on the designer while also potentially discovering new bicycle designs which had not been considered previously viable. Finally, a front-end was created to make it easier for the user to access these algorithms and their results

Voluntary Accounting Policy Choices of Lower -Level Firms in Multi -Firm Organizations.

This study investigates the determinants of accounting choices for subsidiary firms in multi-firm organizations. A subsidiary is defined as either a company that is controlled (i.e., more than 50 percent ownership) by another corporation (its parent ) or is a firm under the parent company\u27s influence (i.e., between 20 and 50 percent ownership). Previous studies focus exclusively on the parent company; hence little is known about making accounting procedure choices for subsidiaries. As a separate legal entity, a subsidiary\u27s accounting policies should be of interest to its creditors, regulators, and noncontrolling minority-interest shareholders. The accounting procedure choices investigated are depreciation and inventory. The sample was comprised of 96 subsidiary-parent matches for depreciation methods and 36 subsidiary-parent matches for inventory methods drawn from the period ranging from 1982 to 1997. Two sets of empirical models were evaluated. First, single firm models that ignore the nature of the parent-subsidiary relationship but, rather, focus solely on the characteristics of the subsidiary firm. Second, multi-firm models were evaluated that expand the single firm model by including variables that capture certain aspects of the parent-subsidiary relationship. Statistically significant results were found for some of the following variables that measure the multi-firm aspect of the subsidiary\u27s accounting choice: (1) the parent company\u27s choice, (2) the percentage ownership held by the parent, and (3) when the subsidiary was acquired from another parent company. In addition, this study contributes by identifying the level of proportional ownership that signals, on average, the exercise of parental influence over the subsidiary\u27s choice

Vibration Damping Circuit Card Assembly

A vibration damping circuit card assembly includes a populated circuit card having a mass M. A closed metal container is coupled to a surface of the populated circuit card at approximately a geometric center of the populated circuit card. Tungsten balls fill approximately 90% of the metal container with a collective mass of the tungsten balls being approximately (0.07) M

Development of air pollution monitoring system / Clive Allen Williams-Hunt

Air Pollution Monitoring System (APMS) is a system that analyzes data to determine the concentration of air pollution at workplace whether it is within safe working environment. The objectives of the study are to determine the design parameter of the air pollution monitoring system in the welding industry using the Quality Function Deployment (QFD) and to evaluate the effectiveness of the air pollution monitoring system. In this study, the data of air pollution were collected at one of the manufacturing factory located at Shah Alam. The data collected will be use as a database for the system to analyze and the data collected during the air pollution monitoring process are toxic gas parameters (i.e. carbon monoxide, carbon dioxide, nitrogen dioxide, sulfur dioxide and ozone). Other information associated with the development of APMS is also collected by using face to face interview to determine the customer requirements on the system parameters. The average values of the air pollution concentration level are used as the database for the system to analyze. The system is being created by using Microsoft Visual Basic while the average values of the air pollution concentration are used for the database by using Microsoft Access. The overall value of the air pollution concentration at the location of interest are calculated to determine the average values and the result indicates that the concentration of air pollution are not exceed the maximum value of concentration level referred to standard by NIOSH and OSHA. There are several characteristics can be improved to enhance the performance of the system