How Much Knowledge of Derived Words Is Needed for Reading?

The study explores the usefulness of the word family as the unit of counting in studies of lexical coverage and comprehension. It determines the proportion of texts covered by the various members of a word family, that is, basewords, inflected words, and derived words, and analyzes the contribution of the affixed words to lexical thresholds. This exploration was performed by a text analysis computer program called Morpholex that analyzes the entire lexis of an entered text, pulling out all words bearing prefixes and suffixes and counting the unaffixed words as basewords. We analyzed a variety of texts, academic and narrative, authentic and simplified, and calculated the number and percentage of basewords and affixes in each text. We also located the most frequent affixes in our text corpus and demonstrated which affixes and how many contributed to 95 per cent and 98 per cent text coverages. Our results show that reaching the lexical thresholds for reading does not require the knowledge of most of the derived words in a word family since a small number of frequent affixes will provide the necessary coverage together with the basewords and inflections.

Analyzing pre-stressed steel arch beams

Techniques are being developed day-by-day to make it possible to pass through larger openings using smaller beam-column sections. Parallel to this trend, there is another necessity to produce not only smaller but also more economical and architecturally attractive beams. The aim of this study is to explain the structural behavior of steel arch beams reinforced using post-tension cables. Due to the effect of these, the arch beam load carrying capacity increases and a smaller sized optimized section can be obtained with a better architectural view. Moreover, it also allows better mechanical and applicable solutions for buildings. For a better understanding of the behavior of the reinforced beam, a steel beam and a steel arch beam with post-tensioned cables were modeled and analyzed using the SAP2000 finite element analysis computer program and compared with each other. In addition, full-scale specimens were prepared for testing to determine the structural behavior and compare the results with those from the computer modeling, the outcome of which was very promising. The similarity between the results inferred that no extra engineering knowledge and effort are needed to design such beams. The predicted (and proved by the testing) beam bearing capacity was 35% higher than that of the unreinforced beam. With just three full-scale tests completed, it was evident that the ratio (35%) could be increased by adjusting the cable post-tension force on much smaller sized beams.

Uncertainty Analysis of the Potential Hazard of MCCI during Severe Accidents for the CANDU6 Plant

This paper illustrates the application of a severe accident analysis computer program to the uncertainty analysis of molten corium-concrete interaction (MCCI) phenomena in cases of severe accidents in CANDU6 type plant. The potential hazard of MCCI is a failure of the reactor building owing to the possibility of a calandria vault floor melt-through even though the containment filtered vent system is operated. Meanwhile, the MCCI still has large uncertainties in several phenomena such as a melt spreading area and the extent of water ingression into a continuous debris layer. The purpose of this study is to evaluate the MCCI in the calandria vault floor via an uncertainty analysis using the ISAAC program for the CANDU6.

Progressive Mooring-Line Failure of a Deepwater MODU in Hurricane Conditions

During 2004–2005, three consecutive category-5 storms hit the central region of Gulf of Mexico (GOM) and damaged numerous drilling and production platforms. Since then, a number of forensic studies have been conducted to better understand the failure causes and mechanism. In this study, a representative deepwater semi-submersible Mobile Offshore Drilling Unit (MODU) that suffered a mooring failure and went adrift during the hurricane Ivan was selected for numerical forensic study. The platform responses and progressive mooring-line failure are simulated in the time domain. A time-domain vessel-mooring coupled dynamic analysis computer program is used to simulate the sequence of progressive mooring-line failure of the MODU in the hindcast Ivan environment, in which the wind, wave, and currents were non-collinear. The case of non-collinear environment is also compared with that of collinear environment. The numerical prediction and simulated results are compared with the available field-analysis data.

Reanalysis of a municipal landfill slope failure near Cincinnati, Ohio, USA

The March 1996 slope failure in a municipal solid waste landfill near Cincinnati, Ohio, USA, is reanalyzed using continuum-mechanics-based procedures implemented in the computer programs FLAC and FLAC3D. A failure mechanism, based on the field observations of the failure, is used for the analyses. The failure mechanism is also implemented in a limit-equilibrium-based slope stability analysis computer program, SSTAB2, to simulate the observed translational character of the failure. The reanalysis results (failure surface, factor-of-safety (FoS), and displacement) from the continuum models are in general agreement with the field data. The FoS values from SSTAB2, FLAC, and FLAC3D range in the expected order. Overall, the reanalysis results supplement previously reported failure analyses. This paper serves two functions: (1) it documents the results of reanalysis using a different (from the previously published) failure mechanism hypothesis for the 1996 landfill slope failure near Cincinnati, Ohio; and (2) it demonstrates the use of 2-D and 3-D continuum models to study: (i) onset of instability; (ii) failure surface geometry and location; and (iii) displacements associated with slope failures.Key words: municipal landfill, slope failure, numerical analysis, limit equilibrium, continuum mechanics, displacement.

SECOND-ORDER ANALYSIS AND DESIGN OF CABLES AND CABLE-FRAMES

Cable structures are lightweighted, simple to fabricate and reusable. They provide effective solutions for large-span structures. Analysis of cables is complex because of their highly geometrically nonlinear behavior. Based on the Lagrangian formulation and a fourth-order polynomial displacement function, the tangent stiffness matrix for a five-node curved cable element is derived and statically condensed to a simple form readily for incorporation into a frame analysis computer program. The program uses the pointwise–equilibrium–polynomial (PEP) element with initial imperfection and the "Nonlinear Integrated Design and Analysis (NIDA)" method for design and nonlinear analysis of cabled structures. Numerical examples demonstrate the robustness and practicality of the proposed method.