Dewatering for Opal Springs Powerhouse Excavation

Planning and execution of dewatering for a deep excavation in coarse alluvium containing cobbles and boulders are discussed. A deep well dewatering system was installed and had to be supplemented with extensive sumping due to inflow from large natural springs, and seepage through a rock fill river diversion embankment. The value of a flexible dewatering plan and provision for backup power are illustrated. Important details of well design are provided. Good engineering, in the form of pumping tests, and design that considers construction requirements are shown to be ?mportant contributors to dewatering success.     

Characterization of micron-size flyash particles by X-ray photoelection spectroscopy (ESCA)

X-ray photoelectron spectroscopy has been used to identify and determine the concentrations and oxidation states for a number of major and minor elements present on the surface of micron-size fly-ash particles. Relative concentrations as a function of depth were obtained for Si, Al, Ti, Fe, Ca, Na, C, O, and S using a sputter-etching procedure. The concentrations of Na, C, and S were found to decrease, and Si, Al, Fe, and Ca were found to increase to a depth of approximately 500 Å. Analysis of a larger size fraction gave depth profiles which were similar to those from micron-size particles. The results are discussed in terms of current models for the formation of fly ash.     

Factors affecting survival, growth, and retrieval of Salmonella Poona on intact and wounded cantaloupe rind and in stem scar tissue

Studies were done to determine the survival and recovery of Salmonella enterica serotype Poona from cantaloupe rind as affected by environmental conditions between the time of contamination and analysis. Detection and enumeration of the pathogen as influenced by analytical methods were also investigated. Combinations of preenrichment broth (lactose broth or universal preenrichment broth), enrichment broth (Rappaport–Vassiliadis broth or tetrathionate broth), and selective agar medium (bismuth sulfite agar or xylose lysine desoxycholate agar) for detecting S. Poona on inoculated cantaloupes stored at 4°C for 7 days or 21°C for 3 days were equivalent in performance. The use of nalidixic acid resistance as a marker in S. Poona and nalidixic acid in media used to enhance detection or enumeration of the pathogen by inhibiting background micro-flora in sanitizer efficacy studies, for example, would not adversely affect its survival on or recovery from cantaloupes. Overall, the composition of the carrier (water or 5% horse serum, a high organic matrix) used to prepare inocula did not influence the number of S. Poona recovered from the intact rind surface, wounds in the surface, or the stem scar tissue. Regardless of inoculation site or composition of the carrier, populations on spot inoculated melons stored at 4°C remained constant between 2 and 24 h after inoculation. The pathogen grew within 24 h in wounds of spot- and dip-inoculated cantaloupes stored at 21°C and 37°C. The addition of up to 1.0% Tween 80 to 0.1% peptone used to remove S. Poona from the rind surface did not adversely affect viability and may have enhanced detachment. Consideration of these observations is recommended when developing a method to test the efficacy of sanitizers in killing salmonellae on the rind surface of inoculated cantaloupes and to detect or enumerate salmonellae that may be natural contaminants.     

2D Large-Eddy Simulation of Lock-Exchange Gravity Current Flows at High Grashof Numbers

Lock-exchange gravity current flows produced by the instantaneous release of a heavy fluid are investigated by means of high-resolution two-dimensional (2D) large-eddy simulation (LES) using a dynamic subgrid scale model for Grashof numbers (Gr) up to 1012. The model is validated using 2D direct numerical simulation results for the classical lock-exchange gravity current flow in an infinite channel with no-slip walls. Then the model is applied to study lock-exchange flows for the case in which the heavier (lock) fluid is initially situated in between a vertical end wall and the lock barrier. Three cases with different aspect ratios of the initial lock fluid are considered for Grashof numbers of the order of 109–1010. It is found that 2D LES is able to capture most of the physics observed in experiments including the evolution of the head, as well as the formation of coherent billow structures at the apex of the head due to growth of the Kelvin-Helmholtz (KH) instabilities. However, due to the fact that three-dimensional instabilities cannot develop in 2D simulations, the coherence of these KH billows in the latter stages of the evolution of the current is found to be stronger compared to the experiment where mixing is sensibly higher at the interface between the current and the surrounding fluid. The LES simulations accurately capture the front and bore velocities in the slumping phase and predict that during the inviscid self-similar phase the front speed decay is proportional to t?1/3, which is consistent with theory, where t=time. A LES simulation at a Grashof number closer to the inviscid range (Gr = 1012) shows that the evolution of the current and the structure of the head region are qualitatively similar to those observed at lower Grashof numbers (Gr>108). The energy balance shows that the higher front velocity in the Gr = 1012 simulation is due to the fact that the amount of mixing (dissipation) decays with the Grashof number. This allows a larger fraction of the potential energy to be converted into kinetic energy. The flow fields are also used to obtain the distributions of the bed shear stress which determine the amount of sediment entrained by a compositional gravity current propagating over a loose bed.     

Promoting Active Learning with Cases and Instructional Modules

In this paper, we propose the use of cases and instructional modules to teach invention, engineering design, and elements of technology management. One way to learn is to study and reflect upon the experience of others. Such experience may be captured in a case. Cases promote active learning by requiring students to assume the roles of participants in the decision making process. Cases are also a vehicle for raising business issues and human resources concerns not usually considered in traditional engineering courses. Real world design and engineering involves risk and uncertainty, tradeoffs and priorities, ethical issues, human elements, and impact assessment. Cases expose students to open ended, ill defined problems whose solution often depends on making assessments, judgments, and decisions about the technical competencies of the organization.     

Iterative Pose Estimation Using Coplanar Feature Points

This paper presents a new method for the computation of the position and orientation of a camera with respect to a known object, using four or morecoplanarfeature points. Starting with the scaled orthographic projection approximation, this method iteratively refines up to two different pose estimates, and provides an associated quality measure for each pose. When the camera distance is large compared with the object depth, or when the accuracy of feature point extraction is low because of image noise, the quality measures for the two poses are similar, and the two pose estimates are plausible interpretations of the available information. In contrast, known methods using a closed form pose solution for four coplanar points are not robust for distant objects in the presence of image noise because they provide only one of the two possible poses and may choose the wrong pose.     

Client records: Ethical and legal considerations.

Examines the legal and ethical problems associated with keeping files on clients. The major focus is on the Canadian Code of Ethics for Psychologists (Canadian Psychological Association, 1988) and the implication of the Code for record keeping by psychologists. Content and types of records kept, including the use of computer assessments and files, are discussed, along with issues of ownership and use of files. Specific suggestions for record keeping, ensuring privacy of computer files, and maintaining record access and retention are made. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Electron beam lithography of copolymeric resists containing styrenes and allyl acrylates

A series of electron beam sensitive negative resists based on styrene allyl methacrylate copolymers and substitutional modifications thereof were prepared and their resist characteristics were investigated. Depending on the molecular parameters, such as monomeric ratios, molecular weights and molecular weight distributions, the sensitivity to electron beam irradiation of the copolymer resist can vary from 10^?7 μC/cm² to 10^?6 μC/cm². A styrene allyl methacrylate copolymer having a 57/43 mol-percent and a molecular weight of 3.3 × 10⁵ shows a sensitivity of 1.4 μC/cm² (Dg^0.5) and a resolution of 1.10 μm line/space at 6000A remaining thickness.