Associative memory scheme for genetic algorithms in dynamic environments

Copyright @ Springer-Verlag Berlin Heidelberg 2006.In recent years dynamic optimization problems have attracted a growing interest from the community of genetic algorithms with several approaches developed to address these problems, of which the memory scheme is a major one. In this paper an associative memory scheme is proposed for genetic algorithms to enhance their performance in dynamic environments. In this memory scheme, the environmental information is also stored and associated with current best individual of the population in the memory. When the environment changes the stored environmental information that is associated with the best re-evaluated memory solution is extracted to create new individuals into the population. Based on a series of systematically constructed dynamic test environments, experiments are carried out to validate the proposed associative memory scheme. The environmental results show the efficiency of the associative memory scheme for genetic algorithms in dynamic environments

Sampling-based Algorithms for Optimal Motion Planning

During the last decade, sampling-based path planning algorithms, such as Probabilistic RoadMaps (PRM) and Rapidly-exploring Random Trees (RRT), have been shown to work well in practice and possess theoretical guarantees such as probabilistic completeness. However, little effort has been devoted to the formal analysis of the quality of the solution returned by such algorithms, e.g., as a function of the number of samples. The purpose of this paper is to fill this gap, by rigorously analyzing the asymptotic behavior of the cost of the solution returned by stochastic sampling-based algorithms as the number of samples increases. A number of negative results are provided, characterizing existing algorithms, e.g., showing that, under mild technical conditions, the cost of the solution returned by broadly used sampling-based algorithms converges almost surely to a non-optimal value. The main contribution of the paper is the introduction of new algorithms, namely, PRM* and RRT*, which are provably asymptotically optimal, i.e., such that the cost of the returned solution converges almost surely to the optimum. Moreover, it is shown that the computational complexity of the new algorithms is within a constant factor of that of their probabilistically complete (but not asymptotically optimal) counterparts. The analysis in this paper hinges on novel connections between stochastic sampling-based path planning algorithms and the theory of random geometric graphs.Comment: 76 pages, 26 figures, to appear in International Journal of Robotics Researc

Evaluation of bacteria for biological control of early blightdisease of tomato

Twenty three bacterial isolate out of 190, exhibiting inhibitory affects against Alternaria solani in preliminary tests, were screened for their activity towards A. solani Ell. and G. Martin) Sor. by a dualculture in vitro assay on nutrient agar (NA) medium and in vivo (whole plant) test. In vitro studies indicated that all the 23 bacterial isolates inhibited the mycelial growth of A. solani by forming inhibition zone ranging from 9.35 to 31.3 mm. The most effective isolate was Serratia plymuthica (IK- 139) (31.3 mm) based on the in vitro test results. Twenty three bacterial isolates were subjected to a whole plant test to investigate their ability to protect the tomato plant against early blight disease. In whole plant tests, 0.5 x 108 cfu/ml bacterial suspension was sprayed and one day later, A. solani spores suspension were applied on tomato seedlings and plants were incubated in moist chamber at 20°C with 95% relative humidity (RH) and 12 h photoperiods for 21 days. Based on the whole plant tests, Paenibacillus macerans-GC subgroup A (1.82), Serratia plymuthica (1.78), Bacillus coagulans (1.75), Serratia marcescens-GC subgroup A (1.50), Bacillus pumilis –GC subgroup B (1.50) and Pantoea agglomerans (1.32) bacterial isolates reduced the disease severity of early blight significantly when compared with control. These results suggest that the bacterial isolates studied have a good potential to be used as biocontrol agents of A. solani in tomato.Key words: Alternaria solani, early blight, biological control, bacterial isolate

Calorimetric and magnetic study for Ni50_{50}Mn36_{36}In14_{14} and relative cooling power in paramagnetic inverse magnetocaloric systems

The non-stoichiometric Heusler alloy Ni$_{50}$Mn$_{36}$In$_{14}$ undergoes a martensitic phase transformation in the vicinity of 345 K, with the high temperature austenite phase exhibiting paramagnetic rather than ferromagnetic behavior, as shown in similar alloys with lower-temperature transformations. Suitably prepared samples are shown to exhibit a sharp transformation, a relatively small thermal hysteresis, and a large field-induced entropy change. We analyzed the magnetocaloric behavior both through magnetization and direct field-dependent calorimetry measurements. For measurements passing through the first-order transformation, an improved method for heat-pulse relaxation calorimetry was designed. The results provide a firm basis for the analytic evaluation of field-induced entropy changes in related materials. An analysis of the relative cooling power (RCP), based on the integrated field-induced entropy change and magnetizing behavior of the Mn spin system with ferromagnetic correlations, shows that a significant RCP may be obtained in these materials by tuning the magnetic and structural transformation temperatures through minor compositional changes or local order changes

The relationship between frontal sinus morphology and skeletal maturation

Background: The aim of this study is to evaluate the relationship between frontal sinus morphology and hand-wrist bone maturation by using postero-anterior (PA) cephalometric radiographs.Materials and methods: The study sample consisted of 220 patients divided into 11 groups based on the hand-wrist radiographs. The right and left maximum height, width and area of the frontal sinus parameters were measured in PA cephalometric radiographs of 220 subjects aged 8–18 years. The hand-wrist skeletal maturation stages were evaluated on the hand-wrist radiographs using the method of Fishman. The Kendall tau-b values were analysed to evaluate the correlation between the hand-wrist skeletal maturation stages and the frontalsinus parameters.Results: The right and left frontal sinus areas and widths were found to be larger in males than in females (p < 0.05). In males, a significant difference was observed in all frontal sinus parameters in different maturation stages (p < 0.001), while a statistically significant correlation was found in females between the left frontal sinus area, right frontal sinus height, right frontal sinus width and different maturation stages (p < 0.05).Conclusions: The relationship between frontal sinus dimensions obtained from PA cephalometric radiographs and hand-wrist maturation stages suggests that frontal sinuses can be used in determining growth and development

Microestructura de quesos blancos turcos bajos en grasa producidos industrialmente, influencia de la homogenización de la crema

The microstructure and fat globule distribution of reduced and low fat Turkish white cheese were evaluated. Reduced and low fat cheeses were manufactured from 1.5% and 0.75% fat milk respectively which were standardized unhomogenized and homogenized cream in a dairy plant. Homogenized and non-homogenized creams and cheese whey were analyzed for fat globule distribution and cheese samples were also analyzed for microstructure characteristics. According to the results, the homogenization of cream decreased the size of fat globules; and showed that a large number of fat particles were dispersed in the in matrix and improved the lubrication of cheese microstructure. According to the micrographs for the fat, which was not removed, they exhibited a more extended matrix with a few small fat globules compared to the defatted micrographs. Homogenization of cream produces small fat globules and unclustured fat globules were found in the resulting whey. These results are important for dairy processors for using cream homogenization as a processing tool at the industrial level.Se estudia la microestructura y distribución de los glóbulos de grasa de quesos blancos turcos bajos en grasa. Quesos con reducida y baja cantidad en grasa fueron fabricados conteniendo entre el 1,5% y 0,75% de grasa de leche, respectivamente, y con cremas homogeneizadas y no homogeneizadas, en una planta de lácteos. Las cremas homogeneizadas y no homogeneizadas y el suero de los quesos se analizaron para determinar la distribución de los glóbulos de grasa y también se analizaron las características de la microestructura de muestras de queso. De acuerdo con los resultados, la homogeneización de la crema reduce el tamaño de los glóbulos de grasa, mostrando un gran número de partículas de grasa dispersa en la matriz de caseína que mejoró la lubricación de la microestructura del queso. De acuerdo con las micrografías de la grasa que no se elimina, estas exhiben una matriz más amplia en la que hay pocos glóbulos de grasa en comparación con las micrografías de las muestras desgrasadas. La homogenización de la crema produce pequeños glóbulos de grasa y el suero resultante contiene glóbulos de grasa no incrustados. Estos resultados son importantes para los procesadores de productos lácteos, y muestran la utilidad de la homogeneización de crema como una herramienta del procesamiento a nivel industrial

Antioxidant and antimutagenic activities of Viscum album fruit ethanolic extract in human lymphocytes

Polyphenolic compounds are widely distributed in plants and known to be excellent antioxidants in vitro. They have the capacity to reduce free-radical formation by scavenging free-radicals. In this studywe have evaluated the antioxidant and antimutagenic potencies of polyphenolic compounds of Viscum album against trichloroethylene (TCE)-induced oxidative and genotoxic damage. V. album extract (VAE0.5 g/ml) protected human lymphocytes against TCE. In chromosomal aberration (CA) analysis, no significant increase in total aberrations were found after treatment with TCE and all VAE concentrations. The mitotic index (MI) showed significant increase in 0.5 ìg/ml VAE samples whencompared with TCE-treated (2 ìM) group. VAE (0.5 ìg/ml) reduced the levels of malondialdehyde (MDA) significantly wherease VAE (1.0 and 2.0 ìg/ml) samples increased MDA concentrations significantly. We have also shown that the various DNA effects of TCE treatment seem to be DNA damages, but not mutations as TCE treated profiles were reverted back to the control like profiles by most probably DNA repair mechanisms in VAE 0.5 g/ml treated group

From Uncertainty Data to Robust Policies for Temporal Logic Planning

We consider the problem of synthesizing robust disturbance feedback policies for systems performing complex tasks. We formulate the tasks as linear temporal logic specifications and encode them into an optimization framework via mixed-integer constraints. Both the system dynamics and the specifications are known but affected by uncertainty. The distribution of the uncertainty is unknown, however realizations can be obtained. We introduce a data-driven approach where the constraints are fulfilled for a set of realizations and provide probabilistic generalization guarantees as a function of the number of considered realizations. We use separate chance constraints for the satisfaction of the specification and operational constraints. This allows us to quantify their violation probabilities independently. We compute disturbance feedback policies as solutions of mixed-integer linear or quadratic optimization problems. By using feedback we can exploit information of past realizations and provide feasibility for a wider range of situations compared to static input sequences. We demonstrate the proposed method on two robust motion-planning case studies for autonomous driving

Multi-Modal Motion Planning Using Composite Pose Graph Optimization

In this paper, we present a motion planning framework for multi-modal vehicle dynamics. Our proposed algorithm employs transcription of the optimization objective function, vehicle dynamics, and state and control constraints into sparse factor graphs, which -- combined with mode transition constraints -- constitute a composite pose graph. By formulating the multi-modal motion planning problem in composite pose graph form, we enable utilization of efficient techniques for optimization on sparse graphs, such as those widely applied in dual estimation problems, e.g., simultaneous localization and mapping (SLAM). The resulting motion planning algorithm optimizes the multi-modal trajectory, including the location of mode transitions, and is guided by the pose graph optimization process to eliminate unnecessary transitions, enabling efficient discovery of optimized mode sequences from rough initial guesses. We demonstrate multi-modal trajectory optimization in both simulation and real-world experiments for vehicles with various dynamics models, such as an airplane with taxi and flight modes, and a vertical take-off and landing (VTOL) fixed-wing aircraft that transitions between hover and horizontal flight modes.Comment: 7 pages, 6 figures, to be included in proceedings of IEEE International Conference on Robotics and Automation 202