This paper presents a real-coded memetic algorithm that combines a high diversity global explorat... more This paper presents a real-coded memetic algorithm that combines a high diversity global exploration with an adaptive local search method to the most promising individuals that adjusts the local search probability and the local search depth. In our proposal we use the individual fitness to decide when local search will be applied (local search probability) and how many effort should be applied (the local search depth), focusing the local search effort on the most promising regions. We divide the individuals of the population into three different categories and we assign different values of the above local search parameters to the individual in function of the category to which that individual belongs. In this study, we analyze the performance of our proposal when tackling the test problems proposed for the Special Session of the IEEE Congress on Evolutionary Computation 2005
American Industrial Hygiene Association Journal, 1987
Potential exposure to Cr(VI) extends to over a million U.S. workers in the plating, paint, steel,... more Potential exposure to Cr(VI) extends to over a million U.S. workers in the plating, paint, steel, tanning and chrome ore processing industries. Historically, Cr(VI) exposure has been monitored using a colorimetric method. This colorimetric method requires acidification of the sample for color development, a step that could cause reduction of Cr(VI) to Cr(III), thus underestimating the Cr(VI) content of the sample. A new method of analysis has been developed that uses ion chromatography (IC) for the measurement and which does not require acidification of the sample. In this method, the same extraction solution of hot 2% NaOH and 3% Na2CO3 as used in the earlier methods is used to dissolve both soluble and insoluble chromates (e.g., PbCrO4, ZnCrO4 and BaCrO4), but it can be carried through the method with only a dilution step before sample injection. Therefore, this method has the advantage of minimizing the potential for Cr(VI) loss by reduction. Another advantage is provided by the IC measurement step, which is not interfered with by colored samples that may affect the colorimetric method. The new method was tested with filter samples of paint aerosol containing PbCrO4 and ZnCrO4. Complete extraction of Cr(VI) from the filter samples was verified by comparison to an independent method in which the filter was completely ashed and analyzed by inductively coupled plasma-atomic emission spectroscopy method. Nothing in the paint samples interfered with the Cr(VI) measurement, nor did five common anions used in a separate test. The method had the sensitivity needed for monitoring at the ACGIH TLV of 0.05 mg Cr(VI)/m3.
This paper describes a non-intrusive rootkit detection tool designed to support forensic investig... more This paper describes a non-intrusive rootkit detection tool designed to support forensic investigations that involve the live analysis of computer systems. The tool, which does not require pre-installation, correlates outputs from multiple system data gathering utilities. Test results indicate that the tool successfully detects several well-known rootkits, including Hacker Defender, AFX, Vanquish, FU and FUto.
Population-based meta-heuristics are algorithms that can obtain very good results for complex con... more Population-based meta-heuristics are algorithms that can obtain very good results for complex continuous optimization problems in a reduced amount of time. These search algorithms use a population of solutions to maintain an acceptable diversity level during the process, thus their correct distribution is crucial for the search. This paper introduces a new population meta-heuristic called “variable mesh optimization” (VMO), in which the set of nodes (potential solutions) are distributed as a mesh. This mesh is variable, because it evolves to maintain a controlled diversity (avoiding solutions too close to each other) and to guide it to the best solutions (by a mechanism of resampling from current nodes to its best neighbour). This proposal is compared with basic population-based meta-heuristics using a benchmark of multimodal continuous functions, showing that VMO is a competitive algorithm.
Scatter search is an evolutionary method that shares with genetic algorithms, a well-known evolut... more Scatter search is an evolutionary method that shares with genetic algorithms, a well-known evolutionary approach, the employment of a combination method that combines the features of two parent vectors to form several offspring. Furthermore, it uses improvement strategies to efficiently produce the local tuning of the solutions. An important aspect concerning scatter search is the trade-off between the exploration abilities of the combination method and the exploitation capacity of the improvement mechanism.In this paper, we deal with a continuous version of the scatter search, which works directly with vectors of real components. Our objective is to study the balance between the reliability induced by the combination method and the accuracy levels provided by the improvement mechanism in continuous scatter search. To do this, we analyse two combination methods that may be applied to continuous scatter search: (1) the BLX-α operator, which is one of the most effective combination methods for real-coded genetic algorithms; and (2) the average combination method, which is the classical combination method for continuous scatter search. We investigate the interrelations that exist between these combination methods and two improvement mechanisms, the Solis and Wets’ algorithm and the Nelder–Mead simplex algorithm, which are well-known continuous local searchers. In addition, we also perform a comparison among continuous scatter search and other continuous optimization algorithms presented in the literature.
This paper presents a real-coded memetic algorithm that combines a high diversity global explorat... more This paper presents a real-coded memetic algorithm that combines a high diversity global exploration with an adaptive local search method to the most promising individuals that adjusts the local search probability and the local search depth. In our proposal we use the individual fitness to decide when local search will be applied (local search probability) and how many effort should be applied (the local search depth), focusing the local search effort on the most promising regions. We divide the individuals of the population into three different categories and we assign different values of the above local search parameters to the individual in function of the category to which that individual belongs. In this study, we analyze the performance of our proposal when tackling the test problems proposed for the Special Session of the IEEE Congress on Evolutionary Computation 2005
American Industrial Hygiene Association Journal, 1987
Potential exposure to Cr(VI) extends to over a million U.S. workers in the plating, paint, steel,... more Potential exposure to Cr(VI) extends to over a million U.S. workers in the plating, paint, steel, tanning and chrome ore processing industries. Historically, Cr(VI) exposure has been monitored using a colorimetric method. This colorimetric method requires acidification of the sample for color development, a step that could cause reduction of Cr(VI) to Cr(III), thus underestimating the Cr(VI) content of the sample. A new method of analysis has been developed that uses ion chromatography (IC) for the measurement and which does not require acidification of the sample. In this method, the same extraction solution of hot 2% NaOH and 3% Na2CO3 as used in the earlier methods is used to dissolve both soluble and insoluble chromates (e.g., PbCrO4, ZnCrO4 and BaCrO4), but it can be carried through the method with only a dilution step before sample injection. Therefore, this method has the advantage of minimizing the potential for Cr(VI) loss by reduction. Another advantage is provided by the IC measurement step, which is not interfered with by colored samples that may affect the colorimetric method. The new method was tested with filter samples of paint aerosol containing PbCrO4 and ZnCrO4. Complete extraction of Cr(VI) from the filter samples was verified by comparison to an independent method in which the filter was completely ashed and analyzed by inductively coupled plasma-atomic emission spectroscopy method. Nothing in the paint samples interfered with the Cr(VI) measurement, nor did five common anions used in a separate test. The method had the sensitivity needed for monitoring at the ACGIH TLV of 0.05 mg Cr(VI)/m3.
This paper describes a non-intrusive rootkit detection tool designed to support forensic investig... more This paper describes a non-intrusive rootkit detection tool designed to support forensic investigations that involve the live analysis of computer systems. The tool, which does not require pre-installation, correlates outputs from multiple system data gathering utilities. Test results indicate that the tool successfully detects several well-known rootkits, including Hacker Defender, AFX, Vanquish, FU and FUto.
Population-based meta-heuristics are algorithms that can obtain very good results for complex con... more Population-based meta-heuristics are algorithms that can obtain very good results for complex continuous optimization problems in a reduced amount of time. These search algorithms use a population of solutions to maintain an acceptable diversity level during the process, thus their correct distribution is crucial for the search. This paper introduces a new population meta-heuristic called “variable mesh optimization” (VMO), in which the set of nodes (potential solutions) are distributed as a mesh. This mesh is variable, because it evolves to maintain a controlled diversity (avoiding solutions too close to each other) and to guide it to the best solutions (by a mechanism of resampling from current nodes to its best neighbour). This proposal is compared with basic population-based meta-heuristics using a benchmark of multimodal continuous functions, showing that VMO is a competitive algorithm.
Scatter search is an evolutionary method that shares with genetic algorithms, a well-known evolut... more Scatter search is an evolutionary method that shares with genetic algorithms, a well-known evolutionary approach, the employment of a combination method that combines the features of two parent vectors to form several offspring. Furthermore, it uses improvement strategies to efficiently produce the local tuning of the solutions. An important aspect concerning scatter search is the trade-off between the exploration abilities of the combination method and the exploitation capacity of the improvement mechanism.In this paper, we deal with a continuous version of the scatter search, which works directly with vectors of real components. Our objective is to study the balance between the reliability induced by the combination method and the accuracy levels provided by the improvement mechanism in continuous scatter search. To do this, we analyse two combination methods that may be applied to continuous scatter search: (1) the BLX-α operator, which is one of the most effective combination methods for real-coded genetic algorithms; and (2) the average combination method, which is the classical combination method for continuous scatter search. We investigate the interrelations that exist between these combination methods and two improvement mechanisms, the Solis and Wets’ algorithm and the Nelder–Mead simplex algorithm, which are well-known continuous local searchers. In addition, we also perform a comparison among continuous scatter search and other continuous optimization algorithms presented in the literature.
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Papers by Daniel Molina