An alternative globalization strategy for unconstrained optimization

We propose a new globalization strategy that can be used in unconstrained optimization algorithms to support rapid convergence from remote starting points. Our approach is based on using multiple points at each iteration to build a sequence of representative models of the objective function. Using the new information gathered from those multiple points, a local step is gradually improved by updating its direction as well as its length. We give a global convergence result and also provide the parallel implementation details accompanied with a numerical study. Our numerical study shows that the proposed algorithm is a promising alternative as a globalization strategy.     

A new rational approximation technique based on transformational high dimensional model representation

In this work, a new rational approximation scheme, based on the recently developed Transformational High Dimensional Model Representation (THDMR) approximation method is developed. As an initial step to the construction of a rational approximation for multivariate functions via THDMR, this paper focuses on the general theoretical background of the method and gives explicit formulae for the computation of such approximants. The performance of the technique is shown by several examples both in univariate and bivariate cases.     

Component testing of repairable systems in multistage missions

We consider the component testing problem of a device that is designed to perform a mission consisting of a sequence of stages. Once a stage is over, the device is overhauled to replace all failed components before the next stage starts to improve mission reliability. The components fail exponentially where the failure rate depends on the stage of the mission. The reliability structure of the device involves a series connection of redundant subsystems. The optimal component testing problem is formulated as a semi-infinite linear programme. We present an algorithmic procedure to compute optimal test times based on the column generation technique, and illustrate it with numerical results.     

Synthesis and photoluminescence of LiCaBO3: M (M: Pb2+ and Bi3+) phosphor

Pure, Pb²⁺ and Bi³⁺ doped LiCaBO₃ materials were prepared by a solution combustion synthesis method. The phase of LiCaBO₃ were determined using the powder XRD and FTIR. The photoluminescent properties of Pb²⁺ and Bi³⁺ doped LiCaBO₃ materials were investigated using spectrofluorometer at room temperature. The emission bands of LiCaBO₃: Pb²⁺ and LiCaBO₃: Bi³⁺ were observed at 296 and 378 nm, respectively. LiCaBO₃ with different Pb²⁺ and Bi³⁺ doping concentrations were analyzed at room temperature. The Stokes shifts of LiCaBO₃: Pb²⁺ and LiCaBO₃: Bi³⁺ were calculated to be 3952 and 6440 cm^?1, respectively.     

Interpolated mapping and investigation of environmental radioactivity levels in soils and mushrooms in the Middle Black Sea Region of Turkey

The activity concentration of natural (²³⁸U, ²³²Th, and ⁴⁰K) and artificial (¹³⁷Cs) radionuclides was determined in 50 samples (obtained from the same station) from various species of mushrooms and soil collected from the Middle Black Sea Region (Turkey). The activities of ²³⁸U, ²³²Th, ⁴⁰K, and ¹³⁷Cs were found as 84 ± 16, 45 ± 14, 570 ± 28, and 64 ± 6?Bq?kg^–1 (dry weight), respectively, in the mushroom samples and as 51?±?6, 41?±?6, 201?±?11, and 44?±?4?Bq?kg^–1, respectively, in the soil samples for the entire area of study. The results of all radionuclide activity measurements, except those of ²³⁸U and ²³²Th in the mushroom samples, are consistent with previous studies. In the soil samples, the mean values of ²³⁸U and ²³²Th are above the world mean, and the activity mean of ⁴⁰K is below the world mean. Finally, the activity estimation was made with both the soil and mushroom samples for unmeasured points within the study area by using the ordinary kriging method. Radiological distribution maps were generated.     

Highly Selective and Stable Florescent Sensor for Cd(II) Based on Poly(azomethine-urethane)

In this study a kind of poly(azomethine-urethane); (E)-4-((2 hydroxyphenylimino) methyl)-2-methoxyphenyl 6-acetamidohexylcarbamate (HDI-co-3-DHB-2-AP) was prepared as in the literature and employed as a new fluorescent probe for detection of Cd(II) concentration. The photoluminescence (PL) measurements were carried out in the presence of several kinds of heavy metals. HDI-co-3-DHB-2-AP gave a linearly and highly stable response against Cd(II) as decreasing a new emission peak at 562 nm. Possible interferences of other ions were found too low. Detection limit of the sensor was found as 8.86?×?10^?4?mol?L^?1. Resultantly, HDI-co-3- DHB-2-AP could be effectively used as an optical Cd(II) sensor.     

Analytic investigation of the (2 + 1)-dimensional Schwarzian Korteweg-de Vries equation for traveling wave solutions

By means of the two distinct methods, the Exp-function method and the extended (G′/G)-expansion method, we successfully performed an analytic study on the (2 + 1)-dimensional Schwarzian Korteweg-de Vries equation. We exhibited its further closed form traveling wave solutions which reduce to solitary and periodic waves. New rational solutions are also revealed.     

Triples of circle-pencils forming a hexagonal three-web in E2

In this paper, the problem of determining of all the triples of circle-pencils forming a hexagonal 3-web is completely solved.Thesis presented to the Faculty of Basic Sciences of the Istanbul Technical university for the degree of Ph. D., in 1974.     

Hexagonal-surface-webs formed by n-pencils of spheres belonging to the same bundle

In this work,it is shown that n pencils of spheres which belong to the same bundle form a hexagonal-surface-web.Firstly,4 pencils of spheres orthogonal to the same sphere are taken into consideration. Later,by means of a suitable transformation,the equations of these 4 pencils of spheres are written in their simplest form and the equation of the surface web is obtained.Then,it is concluded that any 4- pencils of spheres belonging to the same bundle form a hexagonal-surface-web.From this we conclude that a surface n-web which is formed by n pencils of spheres belonging to the same bundle is a hexagonal web.n pencils of spheres are said to belong to the same bundle,if all the spheres cut a fixed sphere orthogonally.     

In situ preparation of palladium / N‐heterocyclic carbene complexes and use for suzuki reaction

The in situ prepared three component system Pd(OAc)₂, 1,3‐dialkylbenzimidazolium halides ( 1a‐e ) and t‐BuOK catalyses quantitatively the Suzuki cross‐coupling of deactivated aryl chloride substrates. 1,3‐Dialkylbenzimidazolium salts ( 1a‐e ) were characterized by conventional spectroscopic methods and elemental analyses.