排序方式: 共有254条查询结果,搜索用时 15 毫秒
81.
Serkan Hosten Amit Khetan Bernd Sturmfels 《Foundations of Computational Mathematics》2005,5(4):389-407
Given a model in algebraic statistics and data, the likelihood function
is a rational function on a projective variety. Algebraic algorithms are presented for
computing all critical points of this function, with the aim of identifying the local
maxima in the probability simplex. Applications include models specified by rank
conditions on matrices and the Jukes–Cantor models of phylogenetics. The maximum likelihood degree of a generic complete intersection
is also determined. 相似文献
82.
Demet Binbaşıoǧlu Serkan Demiriz Duran Türkoǧlu 《Journal of Fixed Point Theory and Applications》2016,18(1):213-224
The study of non-Newtonian calculi was started in 1972 by Grossman and Katz. These calculi provide an alternative to the classical calculus and they include the geometric, anageometric and bigeometric calculi, etc. Recently, Çakmak and Ba?ar (2002) have studied the concept of non-Newtonian metric. Also they have given the triangle and Minkowski’s inequalities in the sense of non-Newtonian calculus. In this paper, we introduce a fixed point theory by defining some topological structures of the relevant non-Newtonian metric space. 相似文献
83.
We determine the maximal gap between the optimal values of an integer program and its linear programming relaxation, where
the matrix and cost function are fixed but the right hand side is unspecified. Our formula involves irreducible decomposition
of monomial ideals. The gap can be computed in polynomial time when the dimension is fixed.
Partially supported by the National Science Foundation (DMS-0200729). 相似文献
84.
Serkan Eryılmaz 《Annals of the Institute of Statistical Mathematics》2011,63(1):101-115
The stress–strength models have been widely used for reliability design of systems. In these models the reliability is defined
as the probability that the strength is larger than the stress. The analysis is then based on the binary reliability theory
since there are two possible states for the system. In this paper, we study the stress–strength reliability in a different
framework assigning more than two states to the system depending on the difference between strength and stress values. In
other words, the stress–strength reliability is studied under multi-state system modeling. System state probabilities are
evaluated and estimated under various assumptions on the system. The multicomponent form is also studied and some results
are provided for large systems. 相似文献
85.
86.
Improvement of catalytic properties of Candida rugosa lipase by sol-gel encapsulation in the presence of magnetic calix[4]arene nanoparticles 总被引:1,自引:0,他引:1
Candida rugosa lipase (CRL) was encapsulated within a chemically inert sol-gel support prepared by polycondensation with tetraethoxysilane (TEOS) and octyltriethoxysilane (OTES) in the presence of N-methylglucamine based calix[4]arene magnetic nanoparticles. The results indicate that the magnetic calix[4]arene based encapsulated lipase particularly has shown high conversion and enantioselectivity. It has also been noticed that the magnetic calix[4]arene based encapsulated lipase has excellent enantioselectivity (E = 460) as compared to the free enzyme (E = 166) with an ee value of >98% for S-Naproxen. 相似文献
87.
Serkan Erdemir Mustafa Yilmaz 《Journal of inclusion phenomena and macrocyclic chemistry》2012,72(1-2):189-196
In this paper the catalytic performance of the immobilized lipases was investigated in the presence of calixarene based polymers using different immobilization techniques. For this reason, Candida rugosa lipase was encapsulated in sol–gel matrices using alkoxysilane precursors and calix[n]arene based silica polymers as additives. The hydrolytic activities of encapsulated lipases were evaluated and compared with the free lipase and covalently immobilized lipases (CnP-L). These encapsulated lipases were also used in the kinetic resolution of the R/S-Naproxen methyl ester. The results indicated that the C6P encapsulated lipase has significantly higher conversion and enantioselectivity as compared to the free lipase; other encapsulated lipases and CnP-L. The optimal pH and temperature region of the C6P encapsulated lipase in the kinetic resolution of the R/S-naproxen methyl ester were 7.0 and 55?°C. Nevertheless, the encapsulated lipases have good stability, adaptability and reusability in comparison with the free enzyme. 相似文献
88.
The gamma-ray tracking technique is a highly efficient detection method in experimental nuclear structure physics. On the basis of this method, two gamma-ray tracking arrays, AGATA in Europe and GRETA in the USA, are currently being tested. The interactions of neutrons in these detectors lead to an unwanted background in the gamma-ray spectra. Thus, the interaction points of neutrons in these detectors have to be determined in the gamma-ray tracking process in order to improve photo-peak efficiencies and peak-to-total ratios of the gamma-ray peaks. In this paper, the recoil energy distributions of germanium nuclei due to inelastic scatterings of 1–5 MeV neutrons were first obtained by simulation experiments. Secondly, as a novel approach, for these highly nonlinear detector responses of recoiling germanium nuclei, consistent empirical physical formulas (EPFs) were constructed by appropriate feedforward neural networks (LFNNs). The LFNN-EPFs are of explicit mathematical functional form. Therefore, the LFNN-EPFs can be used to derive further physical functions which could be potentially relevant for the determination of neutron interactions in gamma-ray tracking process. 相似文献
89.
Infusion-induced changes in the phenolics, antioxidant and colour propeties of St John’s wort (genus, Hypericum; specie, Hypericum perforatum L.) teas were studied for the first time. SJW teas prepared as three different infusions and coded as three (3?min), six (6?min) and twelve minutes (12?min). Investigation of phenolic compounds were performed by LC-DAD-ESI-MS/MS. A total of 18 phenolics including six chlorogenic acids, three phenolic acids, seven flavonoids and two naphtodianthrones were detected. It is worth noting that the phenolic profiles of St John’s wort teas were similar. However, the quantities of phenolic compounds individually and totally changed significantly for different infusion times. The highest total concentration was detected in 12?min (60.03?mg/L), followed by 6?min (54.81?mg/L) and 3?min (33.07?mg/L). The main difference for different infusion times was the hyperoside found as the most abundant phenolic only in 3?min samples. However, for 6?min and 12?minin infusions, chlorogenic acid was the most dominant phenolic compound. Similar to phenolics, antioxidant capacity of tea infusions showed an increasing trend with the extension of infusion time. 相似文献
90.
Şükriye Nihan Karuk Elmas Furkan Ozen Kenan Koran Ibrahim Yilmaz Ahmet Orhan Gorgulu Serkan Erdemir 《Journal of fluorescence》2017,27(2):463-471
Solvent free synthesis of 6,7-dihydroxy-3-(3-chlorophenyl) coumarin (CFHC) was designed and obtained by the interaction of 2-(2,4,5-trimethoxyphenyl)-1-(3-chlorophenyl)acrylonitrile with pyridinium hydrochloride in the presence of silica gel by using microwave irradiation. The characterization of CFHC was confirmed by FT-IR, 1H, 13C, 13C–APT and 2D HETCOR spectroscopy methods. The optical behavior of CFHC towards metal ions was investigated by UV-visible and fluorescence spectroscopy. CFHC showed “on–off” type fluorescence response towards Cu2+ with high selectivity in aqueous solution (CH3CN/H2O, 9/1, v/v). Once binding with Cu2+, CFHC-Cu2+ complex also displayed high selectivity for sulfide, resulting in “off–on” type sensing of sulfide anion. 相似文献