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71.
72.
Site 5 air sparging pilot test, Naval Air Station Cecil Field, Jacksonville, Florida 总被引:8,自引:0,他引:8
A 72-h air sparging pilot test was conducted at Site 5 (Operable Unit 2), Naval Air Station Cecil Field, Jacksonville, FL, to determine performance parameters necessary for full-scale design. The sparge well was completed to a depth of 29 ft, several feet below the groundwater plume contaminated with volatile organic compounds (VOCs), primarily benzene, toluene, ethylbenzene, and xylenes (BTEX). Air flow rates supplied to the sparge well were 3 cubic feet/min (cfm) during the first day, 2 cfm during the second day, and 1 cfm during the third day. Water levels in monitoring wells initially rose approximately 2 ft during the first 4-5 h of the test, then receded back to pre-test equilibrium levels over the next 15 h, for a total duration of water mounding of about 20 h. A small (approximately 0.5 ft) water table drop, with subsequent recovery to equilibrium level, occurred each time the air sparging rate was decreased. Although there is considerable variation depending on direction from the sparge well, the average radius of influence varied from approximately 30 ft at 1 cfm to 50 ft at 3 cfm. The air sparge system was capable of increasing the dissolved oxygen from 0 to 6 or 7 mg/l within 12-15 h of air channels reaching a given location. A lag time of approximately 13 h was observed before air channels reached a radius of 30 ft and dissolved oxygen levels began to increase at that radius. CO(2) (stripped out of the groundwater by the sparging) decreased from a pre-test concentration of 150 to 20 mg/l at r=5 ft, and from 150 to 50 mg/l at r=30 ft, within a period of about 24 h. The rate of VOC mass removal during the pilot test was 0.06 lb/day at a sparge rate of 3 cfm, and it appears that air sparging will effect a rapid cleanup of the VOCs in the Site 5 groundwater plume. 相似文献
73.
This is a review of VLSI Test Principles and Architectures (edited by Laung-Terng Wang, Cheng-Wen Wu, and Xiaoqing Wen), which is partly a textbook and partly a collection of survey articles on testing by top experts. The book's strengths include the practical aspects discussed, the good examples presented, and the depth of many of its chapters. The weaknesses include a lack of consistency of target audience across chapters and a lack of cohesiveness. Nearly everyone will get something out of this book, but prospective purchasers should review the topics of interest to see if the level is right for them. 相似文献
74.
A linear program was developed to help seismically active communities decide: (1) how much to spend on pre-earthquake mitigation that aims to reduce future losses versus waiting until after an event and paying for reconstruction, and (2) which of the many possible mitigation activities to fund so as to minimize overall risk. The mitigation alternatives considered are structural upgrading policies for groups of buildings. Benefits of mitigation are losses avoided in future earthquakes, including structural, non-structural, contents, and time-related losses, and casualties. The model is intended to be used as a tool to support the public regional mitigation planning process. In realistic applications, the model includes millions of variables, thus requiring a special solution method. This paper focuses on two efficient solution algorithms to solve the model—a Dantzig–Wolfe decomposition algorithm and a greedy heuristic algorithm. A comprehensive numerical study compares the two algorithms in terms of solution quality and solution time. The study shows that, compared to the Dantzig–Wolfe algorithm, the heuristic algorithm is much faster as expected, and provides comparable solution quality. 相似文献
75.
Beyond parallel play: Science befriending the art of method acting to advance healing relationships.
Andres-Hyman Raquel C.; Strauss John S.; Davidson Larry 《Canadian Metallurgical Quarterly》2007,44(1):78
Research underscores the central role of factors in healing that appear to relate to the therapeutic relationship. These nonspecific or common factors and placebo effects are often overshadowed by an emphasis in the field on particular empirically supported therapies. Yet relationship variables account for a greater proportion of the variance in treatment outcomes than the technical intervention employed, representing a notable blind spot in our science and, by extension, our practice. As a consequence, clinical instruction in psychology and in the health professions more broadly generally lacks adequate specificity with respect to how to cultivate a healing relationship. Through the elaboration of several techniques derived from theatrical traditions, the authors propose that method acting and similar schools of drama provide a method for honing clinical skills in these areas that is amenable to empirical scrutiny. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
76.
Larson Christine L.; Nitschke Jack B.; Davidson Richard J. 《Canadian Metallurgical Quarterly》2007,7(1):182
The authors examined the time course of affective responding associated with different affective dimensions--anxious apprehension, anxious arousal, and anhedonic depression--using an emotion-modulated startle paradigm. Participants high on 1 of these 3 dimensions and nonsymptomatic control participants viewed a series of affective pictures with acoustic startle probes presented before, during, and after the stimuli. All groups exhibited startle potentiation during unpleasant pictures and in anticipation of both pleasant and unpleasant pictures. Compared with control participants, symptomatic participants exhibited sustained potentiation following the offset of unpleasant stimuli and a lack of blink attenuation during and following pleasant stimuli. Common and unique patterns of affective responses in the 3 types of mood symptoms are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
77.
David Kritchevsky Larry M. Davidson Daniel A. Scott J. J. Van der Watt Dennis Mendelsohn 《Lipids》1988,23(3):164-168
Male Vervet monkeys (7/treatment) were fed a “Western” diet containing 46.2% calories as fat, 39.8% as carbohydrate and 14.0%
as protein. The diet was augmented with 10% cellulose or 10% pectin. A third (control) group of seven monkeys was fed a commercial
ration augmented with fruit and bread. After 34 weeks, serum cholesterol levels were elevated significantly in the two test
groups compared with the controls but there was no difference between the two fiber-fed groups. Serum triglycerides were unaffected.
Liver cholesterol levels were the same in all three groups but liver triglyceride levels were lower in the monkeys fed cellulose.
Biliary lipids were similar in all three groups as were the calculated lithogenic indices. The average aortic sudanophilia
(percent of total area) in the three groups was cellulose, 10.6±2.5; pectin, 8.1±2.5; and control, 1.1±0.4. One animal in
each of the groups fed “Western” diet exhibited an atherosclerotic plaque. The results indicate that there is no difference
between pectin and cellulose with regard to their effects on either lipidemia or aortic sudanophilia in Vervet monkeys fed
a Western-type diet. 相似文献
78.
Curvature greatly complicates the behavior of horizontally curved steel plate girders used in bridge superstructures. The warping stress gradient across the width of I-girder flange plates reduces the vertical bending stress at which the flange plate buckles. The 2007 AASHTO Load and Resistance Factor Design Specifications eliminate the shortcomings of the 2003 AASHTO Guide Specifications for Horizontally Curved Bridges by unifying the flexural design of tangent and curved I-girder bridges. This paper evaluates flange local buckling resistance based upon theoretical and analytical models that consider the effect of stress gradient across the flange coupled with the influence of rotational resistance provided by the web. The developed equations are verified using the finite element method, and the potential impact is demonstrated using the design example presented in the Guide Specifications. 相似文献
79.
Davidson T. L.; Altizer Alicia M.; Benoit Stephen C.; Walls Elwood K.; Powley Terry L. 《Canadian Metallurgical Quarterly》1997,111(5):1014
Experiment 1 used Pavlovian conditioning procedures to show that rats formed distinct memorial representations of 2 (peanut oil and sucrose pellets) unconditioned stimuli (USs) that could be activated by 2 different conditioned stimuli (CSs). After training in Experiment 2, rats injected with the lipid antimetabolite Na-2-mercaptoacetate (MA) responded more to the CS for oil than to the CS for sucrose. This pattern was not shown by rats that received isotonic saline or systemic 2-deoxy-d-glucose (a glucose antimetabolite). By contrast, intracerebroventricular infusion of the glucose antimetabolite 5-thioglucose selectively promoted responding to the CS for sucrose (Experiment 4). Thus, lipoprivic and glucoprivic treatments selectively promoted the activation of the memories of fat and carbohydrate USs, respectively. In Experiment 3, the capacity of MA to augment responding to a CS for oil was abolished for rats that received subdiaphragmatic vagal deafferentation. This indicates that the capacity of lipoprivic signals to selectively activate the representations of fat USs may depend on vagal afferent fibers. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
80.
David L. Davidson 《Journal of Failure Analysis and Prevention》2005,5(1):55-71
Evaluation of a gas turbine disk revealed a crack in the blade attachment area. The subsequent effort to understand the origin
of this crack led to a series of analyses that included computing the stresses on the attachment, characterization of fatigue
crack growth, and a model for fretting fatigue crack growth. These elements were brought together to simulate the conditions
that led to the cracking. It is concluded that the crack was probably caused by fretting fatigue induced by the stresses related
to normal takeoff and landing cycles and exacerbated by aircraft maneuvers, and that short periods of blade resonance may
have contributed to the cracking. If material had not been removed from the attachment surface of the disk by service-induced
wear, it is likely more cracks would have been found. 相似文献