1,687 research outputs found
General -position sets
The general -position number of a graph is the
cardinality of a largest set for which no three distinct vertices from
lie on a common geodesic of length at most . This new graph parameter
generalizes the well studied general position number. We first give some
results concerning the monotonic behavior of with respect to
the suitable values of . We show that the decision problem concerning
finding is NP-complete for any value of . The value of when is a path or a cycle is computed and a structural
characterization of general -position sets is shown. Moreover, we present
some relationships with other topics including strong resolving graphs and
dissociation sets. We finish our exposition by proving that is
infinite whenever is an infinite graph and is a finite integer.Comment: 16 page
Amounts of Tennessee extension staff time expended and numbers of client contacts with selected audiences and teaching methods : fiscal years 1976 and 1978 and possible implications for 1972 and 1977 statewide extension beef production practice checklist surveys and educational programs
Information from the 1972 and 1977 Tennessee Beef Production Practice Checklist Surveys was studied together with data from the Tennessee Extension Management Information System, TEMIS (i.e., agent days expended and clientele contacts made) for Fiscal Years 1976 and 1978 to determine whether there might be possible implications for the survey and Extension\u27s educational program. The classifications of beef survey practices and TEMIS primary subjects were assumed to be acceptable for this study. Data considered from five Districts and the State. Use of various teaching methods also were studied. From the 1972 and 1977 Tennessee Beef Production Surveys, it was found that dollar values of cattle marketed in Tennessee were 273 million, respectively. Positive relation was observed between numbers of contacts and the number of practices used. Recommended practices were grouped under primary TEMIS Subject One, Beef Management and Planning ; Subject Two, Beef Performance Testing ; Subject Three, Beef Diseases ; Subject Four, Beef Facilities and Equipment ; Subject Five, Beef Feeding and Nutrition ; and Subject Six, Beef Pests. Based on 1972 data, four of the Subjects, Subjects One, Two, Three, and Four were below the concern level (i.e. 60 percent) and the other two Subjects were above the concern level. Of the six Subjects mentioned above. Subjects One and Two were the weakest of the six. suggesting the need to emphasize them more as priority areas in Extension\u27s beef educational program. There was a decrease in total agent days expended on beef subjects between FY 1976 and FY 1978, a decrease also was noted in total contacts with beef producers made by agents between FY 1976 and FY 1978. No consequential changes in the relative percents of total agent days expended and contacts made between FY 1976 and FY 1978, excepting an increase of 9 percent in District V contacts related to Subject Seven, a non-practice-related subject. Of Extension methods studied, changes in numbers of agent days devoted to beef Extension work varied from District to District, but, in general, most of the changes for each method were negative in both Individual Methods and Group Meetings, and positive in Mass Media between FY 1976 and FY 1978, though changes in relative percents were not consequential (i.e. 9 percent or greater). It was not clear whether agents had considered priority beef topics identified in the 1972 survey when planning for the period 1974-1978. It was implied that the survey had not appreciably in-fluenced the Extension beef educational program during the period. Recommendations for use of findings and additional study were included
Quantitative Intensity Harmonization of Dopamine Transporter SPECT Images Using Gamma Mixture Models
PURPOSE:
Differences in site, device, and/or settings may cause large variations in the intensity profile of dopamine transporter (DAT) single-photon emission computed tomography (SPECT) images. However, the current standard to evaluate these images, the striatal binding ratio (SBR), does not efficiently account for this heterogeneity and the assessment can be unequivalent across distinct acquisition pipelines. In this work, we present a voxel-based automated approach to intensity normalize such type of data that improves on cross-session interpretation.
PROCEDURES:
The normalization method consists of a reparametrization of the voxel values based on the cumulative density function (CDF) of a Gamma distribution modeling the specific region intensity. The harmonization ability was tested in 1342 SPECT images from the PPMI repository, acquired with 7 distinct gamma camera models and at 24 different sites. We compared the striatal quantification across distinct cameras for raw intensities, SBR values, and after applying the Gamma CDF (GDCF) harmonization. As a proof-of-concept, we evaluated the impact of GCDF normalization in a classification task between controls and Parkinson disease patients.
RESULTS:
Raw striatal intensities and SBR values presented significant differences across distinct camera models. We demonstrate that GCDF normalization efficiently alleviated these differences in striatal quantification and with values constrained to a fixed interval [0, 1]. Also, our method allowed a fully automated image assessment that provided maximal classification ability, given by an area under the curve (AUC) of AUC = 0.94 when used mean regional variables and AUC = 0.98 when used voxel-based variables.
CONCLUSION:
The GCDF normalization method is useful to standardize the intensity of DAT SPECT images in an automated fashion and enables the development of unbiased algorithms using multicenter datasets. This method may constitute a key pre-processing step in the analysis of this type of images.Instituto de Salud Carlos III FI14/00497 MV15/00034Fondo Europeo de Desarrollo Regional FI14/00497 MV15/00034ISCIII-FEDER PI16/01575Wellcome Trust UK Strategic Award 098369/Z/12/ZNetherland Organization for Scientific Research NWO-Vidi 864-12-00
Robust PID tuning. Application to a Mobile Robot Pathtraking problem.
IFAC Digital Control: Past,Present and Future of PlO Control.Terrassa.Spain.2000This paper presents a methodology for tuning PIDs considering the nominal performance and the robustness as control specifications. The synthesis procedure is similar to the Ziegler-Nichols method for PID controllers and can be easily used for industrial processes. As a workbench for testing the PID controller a mobile robot has been used. The path tracking problem of a mobile robot has been used as a workbench for testing the PID controller
Minkowski Functionals of Convergence Maps and the Lensing Figure of Merit
Minkowski functionals (MFs) quantify the topological properties of a given
field probing its departure from Gaussianity. We investigate their use on
lensing convergence maps in order to see whether they can provide further
insights on the underlying cosmology with respect to the standard second-order
statistics, i.e., cosmic shear tomography. To this end, we first present a
method to match theoretical predictions with measured MFs taking care of the
shape noise, imperfections in the map reconstruction, and inaccurate
description of the nonlinearities in the matter power spectrum and bispectrum.
We validate this method against simulated maps reconstructed from shear fields
generated by the MICE simulation. We then perform a Fisher matrix analysis to
forecast the accuracy on cosmological parameters from a joint MFs and shear
tomography analysis. It turns out that MFs are indeed helpful to break the
-- degeneracy thus generating a sort of chain
reaction leading to an overall increase of the Figure of Merit.Comment: 16 pages, 5 figures. Matches published version in PR
A Method for Constrained Multiobjective Optimization Based on SQP Techniques
We propose a method for constrained and unconstrained nonlinear multiobjective optimization problems that is based on an SQP-type approach. The proposed algorithm maintains a list of nondominated points that is improved both for spread along the Pareto front and optimality by solving single-objective constrained optimization problems. These single-objective problems are derived as SQP problems based on the given nondominated points.Under appropriate differentiability assumptions we discuss convergence to local optimal Pareto points. We provide numerical results for a set of unconstrained and constrained multiobjective optimization problems in the form of performance and data profiles, where several performance metrics are used. The numerical results confirm the superiority of the proposed algorithm against a state-of-the-art multiobjective solver and a classical scalarization approach, both in the quality of the approximated Pareto front and in the computational effort necessary to compute the approximation.<br/
Synthesis and Characterization of New Heterocyclic Compounds from 2, 5- dimercapto -1, 3, 4-Thiadiazole and Their Resins
In this research, a new 1, 3, 4-Thiadiazole derivatives have been synthesized by many heterocyclic reactions. Starting from (2, 5 – dimercapto -1, 3, 4-Thiadiazole) a variety of derivatives have been synthesis. Compound (1) was synthesized by the reaction of hydrazine hydrate with carbon disulphide in absolute ethanol. The compound (1) was reacted with 1, 2-dibromoethane in presence of alkali ethanol to give the compound (2). The compound (3) was formed from the reaction of compound (2) with hydrazine hydrate. Schiff base (4) was obtained by reacting of compound (3) with the compound (p-hydroxybenzaldehyde) in absolute ethanol. A variety of phenolic Schiff base (Methylolic, Etheric, and Epoxy) derivatives have been synthesized. Methylolic derivative was synthesized by the reaction of Schiff base (4) with formaldehyde in tetrahydrofuran (THF). Etheric derivative was formed from the reaction of a methylolic Schiff base (5) with saturated alcohol (Methanol).Epoxy derivative was synthesized by the reaction of epichlorohydrine with etheric derivative (6) .The last step of this research was the preparation of a composite material from mixing the Epoxy resin derivative(7), TiO2and morpholine via ring opening. All these derivatives were verified by using (FT-IR, UV) spectra photometer and 1H-NMR spectra. Also, these derivatives were characterized using elemental analysis (C.H.N.S)
Error-Correcting codes fromk-resolving sets
We demonstrate a construction of error-correcting codes from graphs by
means of k-resolving sets, and present a decoding algorithm which makes use
of covering designs. Along the way, we determine the k-metric dimension of
grid graphs (i.e., Cartesian products of paths)
Optimal control of fed-batch processes with particle swarm optimization
Optimal control problems appear in several engineering fields. These problems are often described by sets of nonlinear differential and algebraic equations, usually subject to constraints in the state and control variables. Some bioprocess optimal control problems are revisited and a numerical approach to its solution is introduced.
The numerical procedure used to solve the problems takes advantage of the well know modeling AMPL language, providing an external dynamic library that solve the nonlinear differential equations. The optimal control problem as generally presented belongs to the class of semi-infinite programming (SIP) problems. A transformation of the SIP problem results in a nonlinear optimization problem (NLP) that can be address by off-the-shelf optimization software. The NLP formulation results in nondifferentiable optimization problems were the global solution is mostly desirable. We apply a particle swarm optimization strategy implemented in the MLOCPSOA [13] solver. Particle swarm optimization (PSO) is a stochastic technique that mimics the social behavior of a swarm
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