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1	Quantifying the Effectiveness of Innovative Contracting Strategies on Schedule, Cost and Change Order Gaur, Ankit 16 December 2013 (has links) The transportation infrastructure systems in the United States were built between the 50's and 80's, with 20 years design life. As most of them already exceeded their original life expectancy, State Transportation Agencies (STAs) are now under increased pressure to rebuild deteriorated transportation networks. Over the recent years, state transportation agencies (STAs) have taken into consideration various project delivery approaches apart from conventional project delivery approach to expedite project delivery. Since the introduction of these new alternative delivery approaches, not many substantial studies were conducted that evaluated the performance of these new alternatives. The absence of systematic studies about the effectiveness of these strategies and lack of appropriate analytical tools to evaluate them inhibits the STAs from budgeting precisely and accurately these strategies when they are deliberated for being put into practice. This study tries to address these limitations by evaluating the effectiveness of these strategies. The major objectives of this research were: 1) to evaluate the impact of contracting strategies on dealing with change orders 2) to evaluate the performance of different contracting strategies under varied work type for the state of Florida . For this research the study was conducted to quantify the changes to project duration and cost caused by change orders in the project under different contracting strategies and type of work. This was done through evaluating 2844 completed transportation infrastructure projects, completed between 2002 and 2011 in the state of Florida. These projects comprised of both the conventional projects and innovative alternative projects. The data was then statistically analyzed for evaluating the performance of these contracting strategies. The research concluded that alternative contracting strategies perform much better than conventional contracting in controlling project schedule but are found not to be as effective in controlling the project cost growth. The study also established that project size and work type affect the effectiveness of the contracting strategies. The study indicates that A+B is the worst performing contracting strategy among all the strategies evaluated. The results of this study will help the STAs to make better informed decision regarding selection of contracting strategy for project delivery. Highway Contracting Strategy Change Order Alternative Contracting Strategy
2	Shift gray codes Williams, Aaron Michael 11 December 2009 (has links) Combinatorial objects can be represented by strings, such as 21534 for the permutation (1 2) (3 5 4), or 110100 for the binary tree corresponding to the balanced parentheses (()()). Given a string s = s1 s2 sn, the right-shift operation shift(s, i, j) replaces the substring si si+1..sj by si+1..sj si. In other words, si is right-shifted into position j by applying the permutation (j j−1 .. i) to the indices of s. Right-shifts include prefix-shifts (i = 1) and adjacent-transpositions (j = i+1). A fixed-content language is a set of strings that contain the same multiset of symbols. Given a fixed-content language, a shift Gray code is a list of its strings where consecutive strings differ by a shift. This thesis asks if shift Gray codes exist for a variety of combinatorial objects. This abstract question leads to a number of practical answers. The first prefix-shift Gray code for multiset permutations is discovered, and it provides the first algorithm for generating multiset permutations in O(1)-time while using O(1) additional variables. Applications of these results include more efficient exhaustive solutions to stacker-crane problems, which are natural NP-complete traveling salesman variants. This thesis also produces the fastest algorithm for generating balanced parentheses in an array, and the first minimal-change order for fixed-content necklaces and Lyndon words. These results are consequences of the following theorem: Every bubble language has a right-shift Gray code. Bubble languages are fixed-content languages that are closed under certain adjacent-transpositions. These languages generalize classic combinatorial objects: k-ary trees, ordered trees with fixed branching sequences, unit interval graphs, restricted Schr oder and Motzkin paths, linear-extensions of B-posets, and their unions, intersections, and quotients. Each Gray code is circular and is obtained from a new variation of lexicographic order known as cool-lex order. Gray codes using only shift(s, 1, n) and shift(s, 1, n−1) are also found for multiset permutations. A universal cycle that omits the last (redundant) symbol from each permutation is obtained by recording the first symbol of each permutation in this Gray code. As a special case, these shorthand universal cycles provide a new fixed-density analogue to de Bruijn cycles, and the first universal cycle for the "middle levels" (binary strings of length 2k + 1 with sum k or k + 1). shorthand universal cycles combinatorial generation minimal-change order loopless algorithm efficient algorithm combinations multiset permutations balanced parentheses Dyck words Catalan paths Schroder paths Motzkin words linear-extensions posets connected unit interval graphs inversions binary trees k-ary trees Lyndon words pre-necklaces theoretical computer science discrete mathematics combinatorics brute forcs de Bruijn cycles bubble languages cool-lex order lexicographic order combinatorial enumeration stacker-crane problem traveling salesman problem middle levels fixed-density de Bruijn cycle fixed-content

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Quantifying the Effectiveness of Innovative Contracting Strategies on Schedule, Cost and Change Order

Shift gray codes