Durability of Lightweight Concrete for Bridge Decks

As concrete durability becomes a higher priority for departments of transportation’s acceptability of concrete for bridge decks, consideration of resistance to the penetration of chloride ions has become a key consideration in defining durability. For years the “Rapid Chloride Ion Penetration (RCP) test has been the accepted standard to measure penetrability of concrete to chloride ions. With the movement to use chloride ion penetrability as a part of acceptance criteria for a concrete mix, use of the newer and easier Surface Resistivity (SR) test as an alternative to the slower, more complicated “Rapid Chloride Ion” test became a desirable option. Most of the test results reported in this thesis were from SR tests. This thesis reports the results of extensive tests on concrete specimens cast in the lab and in the field from work on the I-40 Bridge over the French Broad River. While the emphasis was on testing with the SR meter, both SR and RCP tests were performed. When evaluating lightweight concrete, several of the variables that affect both of these tests became evident. The specimen saturation, cement brand, curing method, and time of curing all affected the results. The research concluded that lightweight concrete can be as durable as normal weight concrete, but measured values of chloride ion permeability take longer to reach a predetermined acceptance level. The benefit of internal curing helps lightweight curing make up for the porous aggregate. However, this research did raise important questions about the higher quality control needed for lightweight concrete in mixing, placing and finishing. When evaluating lightweight concrete using Surface Resistivity testing, several precautions should be taken to ensure consistent, reliable and accurate results, including the important consideration of proper curing until the time that SR readings are taken

Type-O\u27s

As technology becomes more heavily integrated in all aspects of modern day society, the ability to accurately and effectively interact with computers becomes increasingly important. This research will investigate a method to increase the memorization of key positions by treating the keyboard as a musical instrument, and not as a word processor. In typing games, such as JumpStart Typing, the user processes simple words generated from a prepared list. This method of memorization solidifies word patterns, but not the positions of the keys. These words consist of prefixes, roots, and suffixes that are used to generate other words; this is not how a musician learns his/her instrument. A musician does not memorize musical phrases that are more likely to appear in future songs he/she may encounter. A musician learns to play his/her instrument, and read sheet music simultaneously, by learning the positions of individual notes. Type-O’s is constructed in Unity3D using the C# programming language. Unity3D is a virtual game developing environment with libraries of game object elements which fulfill basic game developing mechanics, such as physics components and a Cartesian coordinate system. This expedites the production of a three-dimensional computer game, which can then be exported to a number of professional platforms. Because of its privacy and explicit variable declaration requirements, which add to the readability of the scripts, C# is the preferred language by 80% in the Unity3D community. Type-O’s uses a randomized layout to prevent a memorization of the game objects’ positions. As a ball traverses the field bumpers need to be activated by pressing their appropriate key to keep the ball in play. This fast paced environment and random events demand constant attention to the monitor, and not the keyboard and the game mechanics teach typing as a musical instrument

An improved lower bound for Folkman's theorem

Folkman's Theorem asserts that for each $k \in \mathbb{N}$, there exists a natural number $n = F(k)$ such that whenever the elements of $[n]$ are two-coloured, there exists a set $A \subset [n]$ of size $k$ with the property that all the sums of the form $\sum_{x \in B} x$, where $B$ is a nonempty subset of $A$, are contained in $[n]$ and have the same colour. In 1989, Erd\H{o}s and Spencer showed that $F(k) \ge 2^{ck^2/ \log k}$, where $c >0$ is an absolute constant; here, we improve this bound significantly by showing that $F(k) \ge 2^{2^{k-1}/k}$ for all $k\in \mathbb{N}$.Comment: 5 pages, Bulletin of the LM

Fair Value Accounting Fact Or Fancy?

Accounting methods had used historical costs prior to FAS 115 and FAS 157. For financial intermediaries in particular, fair value accounting (FVA) has replaced verifiable historical costs with market valuations that, for illiquid assets, rely on assumptions and are not a priori verifiable. The effect of using these relatively new financial accounting standards has been to convert the valuation basis from historical costs accounting to fair value accounting. The recent literature seems to indicate that the current guideline about fair value accounting may be appropriate in certain cases; but in many cases, it does not appear so. Nevertheless, the Financial Accounting Standards Board (FASB) and the Securities and Exchange Commission (SEC) are, apparently, maintaining their current directives for accounting valuation. The Enron case clearly showed that FVA aided the firm in misstating income statements and balance sheets. Given the accounting literature on the subject, the use of FVA also appears to have contributed to the liquidity crisis of 2008 in a negative way in that (1) the use of FVA combined with mandatory capital adequacy requirement introduced a negative feedback mechanism which caused asset prices to fall more than they otherwise would have, and (2) the use of FVA seems to have caused a lack of confidence in valuations reported on banks’ financial reports. This paper will examine the problems inherent in the replacement of historical cost accounting with fair value accounting, with particular focus on the veracity and verifiability of FVA numbers. Our result indicates that accounting methods cannot possibly be responsible for various valuation models, particularly with respect to certain derivative contracts, such as energy swaps and credit default swaps which cannot be replicated in practice