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37
Efficient Mass Decomposition
, 2005
"... We study the problem of decomposing a positive integer M over a (fixed and finite) weighted alphabet Σ: We want to find nonnegative integers ci such that M = c1a1+...+ckak, where the ai are the positive integer weights of the individual characters and Σ  = k. We refer to the vector (c1,..., ck) ..."
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We study the problem of decomposing a positive integer M over a (fixed and finite) weighted alphabet Σ: We want to find nonnegative integers ci such that M = c1a1+...+ckak, where the ai are the positive integer weights of the individual characters and Σ  = k. We refer to the vector (c1,..., ck) as a witness (of M over Σ), and denote by γ(M) the number of distinct witnesses of M. We present a data structure of size O(ka1) that allows finding all witnesses of any query M in time O(ka1·γ(M)). To the best of our knowledge, this is the first algorithm for the problem with runtime independent of the size of the query M. Construction of the data structure requires O(ka1) time and constant additional space, and is very easy to implement. The problem is motivated by mass spectrometry experiments, where peaks need to be mapped to sample molecules whose mass they could represent. Our simulations show that the algorithm presented performs well on relevant applications.
Reserving resilient capacity for a single commodity with upperbound constraints
 Networks
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ON INTEGER PROGRAMMING AND THE BRANCHWIDTH OF THE CONSTRAINT MATRIX
, 2006
"... Consider an integer program max(c t x: Ax = b, x ≥ 0, x ∈ Z n) where A ∈ Z m×n, b ∈ Z m, and c ∈ Z n. We show that the integer program can be solved in pseudopolynomial time when A is nonnegative and the columnmatroid of A has constant branchwidth. ..."
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Consider an integer program max(c t x: Ax = b, x ≥ 0, x ∈ Z n) where A ∈ Z m×n, b ∈ Z m, and c ∈ Z n. We show that the integer program can be solved in pseudopolynomial time when A is nonnegative and the columnmatroid of A has constant branchwidth.
Reserving Resilient Capacity with Upper Bound Constraints
 IN NETWORKS
, 2000
"... Continuing research begun in [2], we investigate problems of reserving capacity in the arcs of a network, subject to the constraint that, on the failure of any one arc, there is enough reserved capacity on the remaining arcs to support a flow of value T from a source s to a destination t. We also i ..."
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Continuing research begun in [2], we investigate problems of reserving capacity in the arcs of a network, subject to the constraint that, on the failure of any one arc, there is enough reserved capacity on the remaining arcs to support a flow of value T from a source s to a destination t. We also impose upper bounds on the amount of capacity we may reserve on the arcs: this alters the nature of the problem. In the case where each arc has the same upper bound, we investigate the strategy of finding the minimumcost reservation that is itself an acyclic (s; t) flow: we show that such a reservation is easy to find, always has a simple form, and has a cost at most twice that of the optimal solution. We investigate other related problems.
Optimizing Designs based on Risk Approach
 Proceedings of the World Congress on Engineering 2007
"... Abstract — In this paper a new approach to optimize nuclear power plant designs based on global risk reduction are described. In design the focus is on as components quality as redundancy levels. Meanwhile in maintenance and test tasks the focus is on as scheduling tasks as human reliability. The mo ..."
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Abstract — In this paper a new approach to optimize nuclear power plant designs based on global risk reduction are described. In design the focus is on as components quality as redundancy levels. Meanwhile in maintenance and test tasks the focus is on as scheduling tasks as human reliability. The models based on probabilistic risk analysis are used to evaluate several designs and schedules proposed by an hybrid genetic algorithm. The best alternative is chosen to minimize the economical risk of down the production or of have an accident for all reasons considered. This approach has resulted in a new methodology to assure the risk for complex industrial systems too in a global way. So, it is possible considering several aspects such as component qualities, redundancy levels, task schedules for maintenance or tests tasks, and reliability human as a whole. II. REGULATION Nuclear area has a very stringent regulation. In Argentina the regulation is based on risk. For obtain a license of nuclear power plant construction the contractor must demonstrate that the design accomplish with mandatory bound. This requirement can be seen in Fig. 1 The Fig. 1 is an XY graph, the frequency [1/yr] vs. Individual doses [mSv] graph. In this, several points will represent several types of accidents in the installation. If those points are situated under the bound, the plant is acceptable from risk point of view (and in a simplified way). So, in this case the risk is related to accident in the plant.
Multilevel passenger screening strategies for aviation security systems
 Proceedings of Computer, Communication and Control Technologies
, 2006
"... Passenger prescreening is a critical component of aviation security. This paper introduces the Multilevel Allocation Problem (MAP), which models the screening of passengers and baggage in a multilevel aviation security system. A passenger is screened by one of several classes, each of which corres ..."
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Passenger prescreening is a critical component of aviation security. This paper introduces the Multilevel Allocation Problem (MAP), which models the screening of passengers and baggage in a multilevel aviation security system. A passenger is screened by one of several classes, each of which corresponds to a set of procedures using security screening devices, where passengers are differentiated by their perceived risk levels. Each class is defined in terms of its fixed cost (the overhead costs), its marginal cost (the additional cost to screen a passenger), and its security level. The objective of MAP is to assign each passenger to a class such that the total security is maximized subject to passenger assignments and budget constraints. This paper shows that MAP is NPhard, introduces two dynamic programming algorithms for solving MAP in pseudopolynomial time, and introduces a Greedy heuristic that obtains approximate solutions to MAP that use no more than two classes. Examples are constructed using data extracted from the Official Airline Guide (OAG). Analysis of the examples suggests that fewer security classes for passenger screening may be more effective and that using passenger risk information can lead to more effective security screening strategies.
What This Country Needs is an 18¢ Piece
, 2002
"... We consider sets of coin denominations which permit change to be made using as few coins as possible, on average, and explain why the United States should adopt an 18¢ piece. ..."
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We consider sets of coin denominations which permit change to be made using as few coins as possible, on average, and explain why the United States should adopt an 18¢ piece.
Faster mass decomposition
"... Abstract. Metabolomics complements investigation of the genome, transcriptome, and proteome of an organism. Today, the vast majority of metabolites remain unknown, in particular for nonmodel organisms. Mass spectrometry is one of the predominant techniques for analyzing small molecules such as met ..."
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Abstract. Metabolomics complements investigation of the genome, transcriptome, and proteome of an organism. Today, the vast majority of metabolites remain unknown, in particular for nonmodel organisms. Mass spectrometry is one of the predominant techniques for analyzing small molecules such as metabolites. A fundamental step for identifying a small molecule is to determine its molecular formula. Here, we present and evaluate three algorithm engineering techniques that speed up the molecular formula determination. For that, we modify an existing algorithm for decomposing the monoisotopic mass of a molecule. These techniques lead to a fourfold reduction of running times, and reduce memory consumption by up to 94%. In comparison to the classical search tree algorithm, our algorithm reaches a 1000fold speedup. 1
Exact solution method to solve large scale integer quadratic multidimensional knapsack problems
, 2007
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Minimum Cost Sensor Coverage of Planar Regions
"... Abstract—We consider the placement of sensors with circular sensing regions for qcoverage of planar regions. We first consider the placement of sensors of multiple types and costs over a specified set of locations to minimize the total sensors ’ cost. We present two approximate solutions to this pr ..."
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Abstract—We consider the placement of sensors with circular sensing regions for qcoverage of planar regions. We first consider the placement of sensors of multiple types and costs over a specified set of locations to minimize the total sensors ’ cost. We present two approximate solutions to this problem with multiplicative factors of 3 and 1 + 1/l of the optimal cost, where l is a tunable parameter. We then present a method to transform a region coverage instance into an equivalent point coverage instance and show a relationship between the cost of the optimal coverage of the two instances. This transformation enables us to use better studied approximation algorithms for point coverage to derive good sensor deployments for region coverage.