196,102 research outputs found
Physical model tests on new armour block Crablock for breakwaters to come to preliminary design guidance
No full textIn the design of rubble mound breakwaters, nowadays single layer systems using concrete armour units have become more common practice compared to conventional two layer systems. However, after the introduction of the accropode in eighties, a small number of single layer armour units have been developed over the years; for example core-loc, A-jack, xbloc, accropode-II, cubipod and core-loc II. Recently, a new concrete armour unit called crablock has been invented and applied as one layer system in one damaged breakwater at Al Fujeirah, UAE. In contrast to other existing monolayer units, the shape of this unit is symmetrical which allows placing both in uniform and random pattern. As the crablock unit is still under development, no design guidance exists yet for this concrete armour unit. To use crablock as monolayer system the preliminary design guidance on placement of crablock, stability and wave overtopping are required. This led the present research to investigate the placement pattern, packing density and wave overtopping over slope to come with first design guidance for the application of crablock. It should be mentioned that stability of the crablock against wave attack was also looked at, but that will be reported by Mr. André Broere, an MSc-student at Delft University of Technology. The present research was based on a literature study, small scale dry placement tests and small scale hydraulic tests in a wave flume. Regarding to the review of literature studies on the existing single layer units and crablock, set up of dry placement tests and flume tests have been made for this experimental research. Dry placement tests as well as 2D wave flume tests were carried out at the Fluid Mechanics Laboratory of the Faculty of Civil Engineering and Geosciences at Delft University of Technology, Netherlands. Both placement and hydraulic tests were executed with the use of small units. In total 14 independent placement test series were executed to investigate the placement pattern, placing grid and packing density of crablock. All the tests were performed on a 1:4/3 slope with the use of random and uniform placement in a rectangular as well as in a diamond shaped placing grid. Results of placement tests showed that uniform placement of crablock is achievable with the use of relatively small and smooth under layer in a rectangular placing grid. The performance of regular placement using a conventional under layer with size 1/10th to 1/15th of the size of the armour layer was not so satisfactory. Furthermore, it was found that uniform pattern was hardly reachable in a diamond-shaped grid with conventional under layer. However, irregular placement of crablock was certainly easier to construct and possible to place with higher accuracy compared to uniform placement in a diamond grid. It should be noted that all the tests using a conventional underlayer were performed without the fixation of first row due to the difficulties in placement with model crablock units. If this can be fixated by designing dedicated toe units (both in rotation and location) it may perform better. Still, the large underlayer makes it difficult to place uniformly. Finally, two preferred placing patterns appeared from the placement tests, a regular pattern in a rectangular grid using a relatively small under layer and a random pattern in a diamond grid using a conventional under layer. For the determination of wave overtopping, altogether 14 different test series were performed in a wave flume. In this research, two constant spectral wave steepnesses of 0.02 and 0.04 were tested together with two different orientations of units, two different placing grids and four different packing densities. The preferred placing patterns were constructed in a wave flume on a modelled breakwater cross-section in front of the sloping foreshore of 1:30. Each test series was comprised of number of sub tests for specific wave height and period. In each test series, wave heights and periods were continued to measure until the failure of armour slope. The armour layer was reconstructed prior to start of each test series. The test results of 2D flume tests showed that wave overtopping over crablock slope did not vary much between the different test series with same wave steepness. Nevertheless, it was observed that wave overtopping is little bit higher for longer wave period that means for low steepness compared to short period. Based on test results, it was also found that overtopping behaviour does not really change with the change in packing density and also with different placement pattern of armour layer. Regarding to the comparison of relative overtopping rate over crablock armour between test results and empirical prediction, it was found that that empirical equation with assuming roughness factor of 0.45 underestimate the measured wave overtopping over crablock. However, the comparison between the test results on overtopping percentages and estimation by EurOtop (2007) proved that percentage of waves overtopped over crablock can be well predicted by using empirical formula. Furthermore, the measured wave overtopping over crablock slope was found slightly higher in comparison to CLASH (2004) results on other single layer units. This variation was mainly observed for the test results with low wave steepness. Besides relatively low wave steepness, most of the tests on crablock were performed with relatively longer wave periods in comparison to CLASH (2004) which was also one of the triggering factor for higher overtopping over crablock slope compared to CLASH (2004). Moreover, the use of sloping foreshore (1:30) instead of horizontal one by CLASH (2004) might also influence the overtopping behaviour. The 1:30 slope changed the shape of the waves and the waves at the structure toe showed a clear increase in velocity of the wave crest (near or at breaking) The resulting wave overtopping over crablock slope was also compared with the overtopping over xbloc slope measured by DMC (2003). From the comparison, it was found that wave overtopping over crablock is significantly lower compared to xbloc measurements by DMC (2003). Based on the comparison of wave overtopping over different armour slope with and without Ursell parameter, it was recognised that use of the Ursell parameter may explain wave period differences in some cases, but introduces also unexpected differences.Crabloc
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Dr. Glendon Swarthout
No full textHosted by Roger M. Busfield, MSU Assistant Professor of Speech and Theater, Meet the Author is designed to introduce a general audience to a contemporary author and their work through in-depth interviews. This episode features a conversation between Dr. Glendon Swarthout, prolific author and English professor at MSU, and assistant professors Sam S. Baskett and Theodore B. Strandness
A SPATIAL ANALYSIS ON THE PROVISION OF URBAN PUBLIC SERVICES AND THEIR DEFICIENCIES: A STUDY OF SOME SELECTED BLOCKS IN KHULNA CITY, BANGLADESH
No full textIn most of the cities in Bangladesh, there is a considerable lacking in providing public services comparing with the demand. This study aims to identify the deficiencies in providing public services in three selected blocks of Khulna city, Bangladesh. Blocks are considered here as an individual small administrative unit within the jurisdiction of Khulna City Corporation. First the study identified the spatial concentration of the services among the blocks. The comparative situation of the blocks in terms of public services was viewed by location quotient method and Gini coefficient and neighbourhood standard were consider to identify the deficiencies. The study found that two of the blocks are comparatively developed while the other one lag far behind the mean level of development of the city. Lastly on the basis of population and space standard, required facilities for each of the blocks were calculated.Urban Services, Defficiencies, Spatial Analysis, Khulna City.
Simulation of thermal plant optimization and hydraulic aspects of thermal distribution loops for large campuses
No full textFollowing an introduction, the author describes Texas A&M University and its utilities system. After that, the author presents how to construct simulation models for chilled water and heating hot water distribution systems. The simulation model was used in a $2.3 million Ross Street chilled water pipe replacement project at Texas A&M University. A second project conducted at the University of Texas at San Antonio was used as an example to demonstrate how to identify and design an optimal distribution system by using a simulation model. The author found that the minor losses of these closed loop thermal distribution systems are significantly higher than potable water distribution systems. In the second part of the report, the author presents the latest development of software called the Plant Optimization Program, which can simulate cogeneration plant operation, estimate its operation cost and provide optimized operation suggestions. The author also developed detailed simulation models for a gas turbine and heat recovery steam generator and identified significant potential savings. Finally, the author also used a steam turbine as an example to present a multi-regression method on constructing simulation models by using basic statistics and optimization algorithms. This report presents a survey of the author??s working experience at the Energy Systems Laboratory (ESL) at Texas A&M University during the period of January 2002 through March 2004. The purpose of the above work was to allow the author to become familiar with the practice of engineering. The result is that the author knows how to complete a project from start to finish and understands how both technical and nontechnical aspects of a project need to be considered in order to ensure a quality deliverable and bring a project to successful completion. This report concludes that the objectives of the internship were successfully accomplished and that the requirements for the degree of Degree of Engineering have been satisfied
Theoretical and experimental study on the placement of a new concrete armour block
No full textCrablock, a new concrete armour unit has been developed and applied as single layer armour system in one damaged breakwater at UAE. Single layer concrete armour units that exist at this moment have fixed placement pattern mostly random along with designed placing grids and packing densities. The symmetrical shape of crablock makes the unit different from other existing randomly placed single layer units therefore the placement of crablock armour units is also assumed different compared to other single layer blocks. It is worth mentioning that the crablock unit is still under development therefore no design guidance exists at present for this new concrete armour block. To come up with preliminary design guidance for the placement of crablock, an experimental research has been done, which is the subject of this paper. In this laboratory study, in total fourteen placement test series were performed to familiar the placement pattern of crablock as single layer system. In order to establish a reliable dataset, three repetition tests were performed for each test series thus in total 42 tests were conducted on the placement of crablock. This paper describes small scale model placement tests to examine the placement pattern of crablock and also provides a comparison between theoretically designed and actual (measured) placement grid. Based on test results it was observed that crablock armour units can be placed in both uniform and random pattern. Uniform placement of crablock was achievable in a rectangular grid using a relatively small and smooth under layer (1/25th of the size of the armour layer). However, test results showed that a random placement can be best achieved using a conventional diamond shaped grid. Finally, from the placement tests two preferred placing patterns were appeared, a regular pattern in a rectangular grid using a relatively small under layer and a random pattern in a diamond shaped grid using a conventional under layer
Intern experience at CH���M Hill, Inc.: an internship report
No full textIncludes author's vita"Submitted to the College of Engineering of Texas A&M University in partial
fulfillment of the requirement for the degree of Doctor of Engineering."Includes bibliographical referencesA review of the author's internship experience with CH���M HILL, Inc.
during the period September 1975 through May 1976 is presented. During this nine month
internship the author worked as an Engineer II in the Industrial Processes discipline of this
large consulting engineering firm... The author's prime responsibility was as one of three
lead design engineers on the design of a large wastewater treatment facility for a pulp mill
in Hoquiam, Washington owned by ITT Rayonier Inc. The work generally consisted of the design
of individual treatment units and associated piping and pumping. The purpose of the project
was to provide wastewater treatment capabilities that would satisfy the effluent limitations
(standards) imposed upon the mill by the State of Washington Department of Ecology and the
U.S. Environmental Protection Agency. The author's assignment also entailed necessary
interaction with the project manager and other CH���M HILL design engineers and support staff
members, the client's representatives, and representatives of two other consulting engineering
firms working on the project. Thus, the internship position at CH���M HILL provided considerable
experience coordinating the author's work with the work of other engineers, guiding the design
and administrative efforts of a support staff, and interacting regularly with the client and
other consulting firms. This broad exposure to a variety of engineering and organizational
problems provided a valuable educational experience
Transition to turbulence in a qblique shock-wave/boundary-layer interaction at M=15
No full textDirect numerical simulations are carried out for different forcing techniques to trigger transition during the interaction between an oblique shock-wave and a laminar boundary-layer at M = 1.5. Three forcing methods are used: a) forcing of oblique unstable modes, whose shape and behaviour are determined by the local linear stability theory, b) broadband free-stream acoustic disturbances, and c) a cold plasma flow control device. While the oblique-mode breakdown is dominant for low-amplitude forcing, long streaky structures drive the transition process in a high-amplitude disturbance environment. LES are also performed on the experimental setup by the Institute of Theoretical and Applied Mechanics (ITAM) from Novosibirsk State University with cold plasma actuation. As well as the disturbance type, the effect of Reynolds number and forcing amplitude will be investigated
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