1,929 research outputs found
The Tourist and Recreational Function of Mielno
W opracowaniu szczegółowej ocenie poddano zagospodarowanie turystyczne, użytkowanie ziemi oraz ruch turystyczny w celu określenia funkcji turystyczno-wypoczynkowej Mielna
Struktura społeczna wsi w Królestwie Polskim
Zadanie pt. „Digitalizacja i udostępnienie w Cyfrowym Repozytorium Uniwersytetu Łódzkiego kolekcji czasopism naukowych wydawanych przez Uniwersytet Łódzki” nr 885/P-DUN/2014 zostało dofinansowane ze środków MNiSW w ramach działalności upowszechniającej naukę
Pamięci profesora Zbigniewa Kuchowicza (1927-1991)
Zadanie pt. Digitalizacja i udostępnienie w Cyfrowym Repozytorium Uniwersytetu Łódzkiego kolekcji czasopism naukowych wydawanych przez Uniwersytet Łódzki nr 885/P-DUN/2014 zostało dofinansowane ze środków MNiSW w ramach działalności upowszechniającej naukę
Properties of Microlensing Central Perturbations by Planets in Binary Stellar Systems under the Strong Finite-Source Effect
We investigate high-magnification events caused by planets in wide binary
stellar systems under the strong finite-source effect, where the planet orbits
one of the companions. From this, we find that the pattern of central
perturbations in triple lens systems commonly appears as a combination of
individual characteristic patterns of planetary and binary lens systems in a
certain range where the sizes of the caustics induced by a planet and a binary
companion are comparable, and the range changes with the mass ratio of the
planet to the planet-hosting star. Specially, we find that because of this
central perturbation pattern, the characteristic feature of high-magnification
events caused by the triple lens systems appears in the residual from the
single-lensing light curve despite the strong finite-source effect, and it is
discriminated from those of the planetary and binary lensing events and thus
can be used for the identification of the existence of both planet and binary
companion. This characteristic feature is a simultaneous appearance of two
features. First, double negative-spike and single positive-spike features
caused by the binary companion appear together in the residual, where the
double negative spike occurs at both moments when the source enters and exits
the caustic center and the single positive spike occurs at the moment just
before the source enters into or just after the source exits from the caustic
center. Second, the magnification excess before or after the single
positive-spike feature is positive due to the planet, and the positive excess
has a remarkable increasing or decreasing pattern depending on the source
trajectory.Comment: 12 pages, 3 figures, accepted for publication in Ap
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Trinuclear Cage-Like Zn(II) Macrocyclic Complexes: Enantiomeric Recognition and Gas Adsorption Properties.
Three zinc(II) ions in combination with two units of enantiopure [3+3] triphenolic Schiff-base macrocycles 1, 2, 3, or 4 form cage-like chiral complexes. The formation of these complexes is accompanied by the enantioselective self-recognition of chiral macrocyclic units. The X-ray crystal structures of these trinuclear complexes show hollow metal-organic molecules. In some crystal forms, these barrel-shaped complexes are arranged in a window-to-window fashion, which results in the formation of 1D channels and a combination of both intrinsic and extrinsic porosity. The microporous nature of the [Zn3 12 ] complex is reflected in its N2 , Ar, H2 , and CO2 adsorption properties. The N2 and Ar adsorption isotherms show pressure-gating behavior, which is without precedent for any noncovalent porous material. A comparison of the structures of the [Zn3 12 ] and [Zn3 32 ] complexes with that of the free macrocycle H3 1 reveals a striking structural similarity. In H3 1, two macrocyclic units are stitched together by hydrogen bonds to form a cage very similar to that formed by two macrocyclic units stitched together by Zn(II) ions. This structural similarity is manifested also by the gas adsorption properties of the free H3 1 macrocycle. Recrystallization of [Zn3 12 ] in the presence of racemic 2-butanol resulted in the enantioselective binding of (S)-2-butanol inside the cage through the coordination to one of the Zn(II) ions.This work was supported by the NCN (NarodoweCentrumNauki, Poland) (grant 2011/03/B/ST5/01060).D.P.and J.L.thank the FNP Program“Mistrz” for financial support, and D.F.-J. thanks the Royal Society for funding through a University Research Fellowship.This is the author accepted manuscript. The final version is available from Wiley via http://dx.doi.org/10.1002/chem.20150347
Interfacial Intermetallic Growth and Strength of Composite Lead-Free Solder Alloy Through Isothermal Aging
The effects of particle reinforcement of Sn-4.0wt.%Ag-0.5wt.%Cu (SAC405) lead-free solder on interfacial intermetallic layer growth and strength of the ensuing joints through short-term isothermal aging (150°C) were studied. Composite solders were prepared by either incorporating 2wt.% Cu (3μm to 20μm) or Cu2O (∼150nm) particles into SAC405 paste. Aggressive flux had the effect of reducing the Cu2O nanoparticles into metallic Cu which subsequently reacted with the solder alloy to form the Cu6Sn5 intermetallic. While all solders had similar interfacial intermetallic growth upon reflow, both of the composite solders' growth rates slowed through aging to reach a common growth rate exponent of approximately 0.38, considerably lower than that of the nonreinforced solder (n=0.58). The nanoscale reinforced solder additionally exhibited the highest tensile strength in both the initial and aged conditions, behavior also attributed to its quick conversion to a stable microstructur
A Study of the Shear Response of a Lead-Free Composite Solder by Experimental and Homogenization Techniques
The current study proposes a combined experimental and modeling approach to characterize the mechanical response of composite lead-free solders. The influence of the reinforcement volume fraction on the shear response of the solder material in the joint is assessed. A novel optimized geometry for single lap shear specimens is proposed. This design minimizes the effect of plastic strain localization, leading to a significant improvement of the quality of experimental data. The constitutive model of the solder material is numerically identified from the load-displacement response of the joint by using inverse finite element identification. Experimental results for a composite solder with 0.13 reinforcement volume fraction indicate that the presence of the reinforcement leads to a 23% increase of the ultimate stress and a 50% decrease of the ultimate strain. To interpret experimental data and predict the elastoplastic response of the composite solder for varying particle volume fraction, a three-dimensional (3D) homogenization model is employed. The agreement between experiments and homogenization results leads to the conclusion that the increase in the ultimate strength and the decrease in ductility are to be attributed to load sharing between matrix material and particles with the development of a significant triaxial stress state which restricts plastic flow in the matri
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