87,120 research outputs found
Applying the possibilistic C-means algorithm in kernel-induced spaces
No full textIn this paper, we study a kernel extension of the classic possibilistic c-means. In the proposed extension, we implicitly map input patterns into a possibly high-dimensional space by means of positive semidefinite kernels. In this new space, we model the mapped data by means of the possibilistic clustering algorithm. We study in more detail the special case where we model the mapped data using a single cluster only, since it turns out to have many interesting properties. The modeled memberships in kernel-induced spaces yield a modeling of generic shapes in the input space. We analyze in detail the connections to one-class support vector machines and kernel density estimation, thus, suggesting that the proposed algorithm can be used in many scenarios of unsupervised learning. In the experimental part, we analyze the stability and the accuracy of the proposed algorithm on some synthetic and real datasets. The results show high stability and good performances in terms of accuracy
5th International Workshop on Automated and verifiable Software sYstem DEvelopment (ASYDE 2023) at 38th IEEE/ACM International Conference on Automated Software Engineering (ASE 2023)
No full textDuring the last three decades, automation in software development has gone mainstream. Software development teams strive to automate as much of the software development activ-ities as possible, spanning requirements specification, system modeling, code generation, testing, deployment, verification, as well as release phases, project status reporting and system maintenance. Automation helps to reduce development time and cost, as well as to concentrate know ledge by bringing quality into every step of the development process
Use of hypervirulent Agrobacterium tumefaciens carrying a binary vector to transform eggplant (Solanum melongena) cotyledonary leaf discs
No full textAgrobacterium tumefaciens strain A281 carrying plasmid pGA472 was used to stably transform eggplant cotyledonary tissue to kanamycin resistance. Both presence and expression of the neo transgene were demonstrated by DNA dot blot analysis and NPT II enzyme assays. Kanamycin-resistant plantlets were regenerated by organogenesis after six months of culture
Stable transformation of eggplant (Solanum melongena L.) by cocultivation of tissues with Agrobacterium tumefaciens carrying a binary plasmid vector
No full textStable transformation of eggplant to kanamycin resistance was obtained by cocultivation of cotyledonary and young leaves with the hypervirulent, fully oncogenic Agrobacterium tumefaciens strain A281 carrying plasmid pGA472. No transformation was observed when using the disarmed A. tumefaciens LBA4404 strain carrying pGA472 or when using either strain for cocultivation with eggplant suspension cells. The NPTII enzyme and DNA dot blot assays performed on callus cells growing in the presence of kanamycin indicated both the presence and expression of the foreign gene. The highest proportion of transformed explants was obtained from intact cotyledonary leaf pieces while the highest NPTII enzyme specific activity was detected in callus cells originating from superficially wounded cotyledonary leaf pieces. Kanamycin-resistant plantlets were regenerated after six months in culture. © 1989 Springer-Verlag
Robustness Analysis for Terminal Phases of Re-entry Flight
No full textAdvancements in the current practices used in robustness analysis for FCS design refinement by introducing a method that takes into account nonlinear effects of multiple uncertainties over the whole trajectory, to be used before robustness is finally assessed with MC analysis has been reported. Current practice in FCS robustness analysis for this kind of application mainly relies on the theory of linear time-invariant (LTI) systems. The method delivers feedback on the causes of requirement violation and adopts robustness criteria directly linked to the original mission or system requirements, such as those employed in MC analyses. The nonlinear robustness criterion proposed in the present work is based on the practical stability and/or finite time stability concepts. The practical stability property improves the accuracy in robustness evaluation with respect to frozen-time approaches, thus reducing the risk of discovering additional effects during robustness verification with Monte Carlo techniques
Why diffusion‐based preconditioning of Richards equation works: Spectral analysis and computational experiments at very large scale
No full textWe consider here a cell-centered finite difference approximation of the Richards equation in three dimensions, averaging for interface values the hydraulic conductivity K=K(p), a highly nonlinear function, by arithmetic, upstream and harmonic means. The nonlinearities in the equation can lead to changes in soil conductivity over several orders of magnitude and discretizations with respect to space variables often produce stiff systems of differential equations. A fully implicit time discretization is provided by backward Euler one-step formula; the resulting nonlinear algebraic system is solved by an inexact Newton Armijo-Goldstein algorithm, requiring the solution of a sequence of linear systems involving Jacobian matrices. We prove some new results concerning the distribution of the Jacobians eigenvalues and the explicit expression of their entries. Moreover, we explore some connections between the saturation of the soil and the ill conditioning of the Jacobians. The information on eigenvalues justifies the effectiveness of some preconditioner approaches which are widely used in the solution of Richards equation. We also propose a new software framework to experiment with scalable and robust preconditioners suitable for efficient parallel simulations at very large scales. Performance results on a literature test case show that our framework is very promising in the advance toward realistic simulations at extreme scale
Parallel Sparse Computation Toolkit
No full textThis paper presents a new software framework for solving large and sparse linear systems on current hybrid architectures, from small servers to high-end supercomputers, embedding multi-core CPUs and Nvidia GPUs at the node level. The framework has a modular structure and is composed of three main components, which separate basic functionalities for managing distributed sparse matrices and executing some sparse matrix computations involved in iterative Krylov projection methods, eventually exploiting multi-threading and CUDAbased programming models, from the functionalities for setup and application of different types of one-level and multi-level algebraic preconditioners
Effect of of fungal phenoloxidases expression in plant and green microalgae on olive mill wastewaters phenols content
No full textGene-transfer by cocultivation of mature embryos with Agrobacterium tumefaciens - application to cowpea (Vigna unguiculata walp)
No full textOur studies have shown for the first time that chimeric transgenic cowpea plants could be produced from mature embryos cocultivated with Agrobacterium tumefaciens. Pilot studies demonstrated the possibility of obtaining transgenic cowpea callus cells following cocultivation of excised mature embryos with oncogenic hypervirulent Agrobacterium tumefaciens A281 (pTiBo542/pGA472). Subsequently, cowpea plants chimeric for a gus transgene were obtained by cocultivating mature embryos excised from ungerminated seeds with disarmed A. tumefaciens C58 (pGV2260/p35SGUSINT) carrying a plant-expressable gus gene interrupted by an intron. Studies of reporter transgene expression showed that transformed cells were mostly located in the subepidermal regions of the plant stems
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