statistical limit
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2021 ◽  
Author(s):  
Axel Olesund ◽  
Jessica Johnsson ◽  
Fredrik Edhborg ◽  
Shima Ghasemi ◽  
Kasper Moth-Poulsen ◽  
...  

Triplet-triplet annihilation photon upconversion (TTA-UC) is a process in which triplet excitons combine to form emissive singlets, and holds great promise to improve the spectral match in solar energy and biological applications. While high TTA-UC quantum yields has been reported for e.g., red-to-green TTA-UC systems there are only a few examples of visible-to-UV transformations in which the quantum yield reaches 10%. In this study we investigate the performance of six annihilators when paired with the sensitizer 2,3,5,6-tetra(9H-carbazol-9-yl)benzonitrile (4CzBN), a purely organic compound that exhibits thermally activated delayed fluorescence (TADF). We report a record-setting TTA-UC quantum yield of 16.8% (out of a 50% maximum) for 1,4-bis((triisopropylsilyl)ethynyl)naphthalene (TIPS-Naph), demonstrating the first example of a visible-to-UV TTA-UC system approaching the classical spin-statistical limit of 20%. Three other annihilators, of which 2,5-diphenylfuran (PPF) has never been used for TTA-UC previously, also showed impressive performances with TTA-UC quantum yields above 12%. In addition, a new method to determine the rate constant of triplet-triplet annihilation is proposed in which only time-resolved emission measurements are needed, circumventing the need for more challenging transient absorption measurements. The results reported herein represent an important step towards highly efficient visible-to-UV TTA-UC systems which hold great potential for driving high-energy photochemical reactions.


2021 ◽  
Vol 137 (1) ◽  
Author(s):  
Paolo Azzurri ◽  
Gregorio Bernardi ◽  
Sylvie Braibant ◽  
David d’Enterria ◽  
Jan Eysermans ◽  
...  

AbstractThe FCC-ee offers powerful opportunities to determine the Higgs boson parameters, exploiting over $$10^6$$ 10 6 $${ \hbox {e}^+\hbox {e}^- \rightarrow \hbox {ZH}}$$ e + e - → ZH events and almost $$10^5$$ 10 5 $${ \hbox {WW} \rightarrow \hbox {H}}$$ WW → H events at centre-of-mass energies around 240 and 365 GeV. This essay spotlights the important measurements of the ZH production cross section and of the Higgs boson mass. The measurement of the total ZH cross section is an essential input to the absolute determination of the HZZ coupling—a “standard candle” that can be used by all other measurements, including those made at hadron colliders—at the per-mil level. A combination of the measured cross sections at the two different centre-of-mass energies further provides the first evidence for the trilinear Higgs self-coupling, and possibly its first observation if the cross section measurement can be made accurate enough. The determination of the Higgs boson mass with a precision significantly better than the Higgs boson width (4.1 MeV in the standard model) is a prerequisite to either constrain or measure the electron Yukawa coupling via direct $${ \hbox {e}^+\hbox {e}^- \rightarrow \hbox {H}}$$ e + e - → H production at $$\sqrt{s} = 125$$ s = 125  GeV. Approaching the statistical limit of 0.1% and $${\mathcal {O}}(1)$$ O ( 1 )  MeV on the ZH cross section and the Higgs boson mass, respectively, sets highly demanding requirements on accelerator operation (ZH threshold scan, centre-of-mass energy measurement), detector design (lepton momentum resolution, hadronic final state reconstruction performance), theoretical calculations, and analysis techniques (efficiency and purity optimization with modern tools, constrained kinematic fits, control of systematic uncertainties). These challenges are examined in turn in this essay


2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
Ö. Kişi ◽  
M. B. Huban ◽  
M. Gürdal

In this paper, some existing theories on convergence of fuzzy number sequences are extended to I 2 -statistical convergence of fuzzy number sequence. Also, we broaden the notions of I -statistical limit points and I -statistical cluster points of a sequence of fuzzy numbers to I 2 -statistical limit points and I 2 -statistical cluster points of a double sequence of fuzzy numbers. Also, the researchers focus on important fundamental features of the set of all I 2 -statistical cluster points and the set of all I 2 -statistical limit points of a double sequence of fuzzy numbers and examine the relationship between them.


2021 ◽  
Vol 13 (2) ◽  
pp. 433-451
Author(s):  
S.R. Sadigova

In this work, the concept of a point $\mu$-statistical density is defined. Basing on this notion, the concept of $\mu$-statistical limit, generated by some Borel measure $\mu\left(\cdot \right)$, is defined at a point. We also introduce the concept of $\mu$-statistical fundamentality at a point, and prove its equivalence to the concept of $\mu$-stat convergence. The classification of discontinuity points is transferred to this case. The appropriate space of $\mu$-stat continuous functions on the segment with sup-norm is defined. It is proved that this space is a Banach space and the relationship between this space and the spaces of continuous and Lebesgue summable functions is considered.


2021 ◽  
Vol 6 ◽  
pp. 57-72
Author(s):  
А.И. Казьмин ◽  
П.А. Федюнин ◽  
Д.П. Федюнин

The widespread use of anisotropic composite dielectric coatings operating in the microwave range in various science-intensive areas has led to the search and selection of effective methods of radio wave nondestructive testing of their electrophysical parameters. The existing approaches based on the estimation of the reflection and transmission coefficients of electromagnetic waves have low accuracy and reliability of estimating the components of the complex permittivity tensor and the thickness of such coatings, do not take into account their frequency dispersion and placement on a metal base. We present the new method of local measurements of components of the complex permittivity tensor with allowance for their frequency dispersion and a thickness anisotropic dielectric coatings with radial surface microwaves. The method is based on the solution of inverse problem in the determination of components of the complex permittivity tensor and a thickness coatings from the frequency and angular dependence of the attenuation coefficient of the field of a radial surface electromagnetic wave excited in a test sample. A numerical and experimental study show that for a measurement bandwidth of 9–13,5 GHz the errors in estimating the anisotropy coefficients do not exceed 10% with a confidence coefficient of 0.95. We introduce and substantiate a statistical limit of the resolution of the anisotropy of permittivity; this makes it possible to evaluate the possibility of discriminating between two close values any pair of components of the permittivity tensor. Numerical and field experiments have shown that the method can provide their assessment with a difference of 0.2–0.3% or less in the frequency band of 9–13.5 GHz.


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