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Observation‐based simulations of the ionosphere were performed with the NRLMSISE‐00 model for six locations around the globe during 1–9 February 2022, which includes the so‐called Starlink Storm. Unlike other studies, we focused on the magnetically quiet days around the storm. Unexpectedly, the observed values of the F2‐layer peak density were ∼50% larger than the simulated values. We show that this implies that the daytime O density in the thermosphere was systematically ∼30% larger than the NRLMSISE‐00 predicts. Further investigation shows that this discrepancy is not an exclusive feature of the period around the Starlink Storm and a similar problem happens for some periods for different years. It is unclear if the reason is an actual increase of the O density or its underestimation by the model. Resolving this problem is critical for providing accurate predictions of the atmosphere to avoid the degradation of normal operation or even loss of space assets. Plain Language Summary In early February 2022, dozens of Starlink satellites were lost after a moderate magnetic storm which was not expected to be able to cause significant perturbations in the Earth's atmosphere but did that. Numerous investigations showed the Starlink loss happened because of a remarkable increase of density of the upper atmosphere (thermosphere) caused by the storm. Teams of researchers were focused on the storm days 3 and 4 February. We got curious about the conditions in the thermosphere around the storm days. We employed observational data collected by ionospheric radars around the globe and conducted simulations with a physical model of the ionosphere‐thermosphere system, which allowed us to obtain the thermosphere composition. Our results indicate that the density of atomic oxygen in the thermosphere was one third larger than predictions of the standard model of the atmosphere during the periods before and after the storm. This means that the thermosphere was already poorly predictable prior to the storm occurrence. It is possible that this affected the thermosphere behavior during the storm. Also, we found that a similar problem with the prediction of the thermosphere by the standard model happens from time to time posing threat to the safety of spacecraft. Key Points For magnetically quiet days, the observed daytime NmF2 values were ∼50% larger than those simulated using the NRLMSISE‐00 model This implies ∼30% larger neutral O density comparing with the NRLMSISE‐00 model prediction or the density underestimation by the model Similar problem with the O density prediction happens for some periods for different years

Measurement of properties of short-lived resonances produced in heavy-ion collisions plays an important role in study of the hot and dense medium produced in such collisions. The study of resonance production in heavy-ion collisions is an important part of the physical program of the MPD experiment at NICA. We present results of feasibility studies for measurement of (1020), and meson production in Bi Bi collisions at GeV using the MPD detector at NICA collider. Results are obtained using full-scale Monte Carlo simulations of heavy-ion collisions and the experimental setup.

A series of novel fluorescent donor–acceptor–donor (D-A-D) dyes containing [1,2,5]oxadiazolo[3,4-d]pyridazine and its 1-oxide as electron-withdrawing groups has been synthesized and thoroughly investigated using X-ray diffraction and molecular spectroscopy methods. This study showed that the introduction of N-oxide into the 1,2,5-oxadiazole ring in the acceptor fragment leads to a significant decrease in the luminescence intensity and quantum yield of the dyes. A comprehensive comparison of the photophysical properties of the obtained compounds containing the 1,2,5-oxadiazole ring with the previously studied [1,2,5]thia- and 1,2,5-selenadiazolo[3,4-d]pyridazine analogs showed that the oxygen substitution in the acceptor fragment shifts the phosphorescence maximum from the NIR region of 980–1100 nm to the red region of 690–770 nm. In contrast, for oxygen- and sulfur-containing dyes, purely red fluorescence with a maximum in the spectral range of 620–900 nm is observed. The crystal structures of furoxan-containing 3d·½CHCl3 and furazan-containing 4d exhibit a non-planar [1,2,5]oxadiazolo[3,4-d]pyridazine fragment. We have found that short non-covalent interactions of the furoxan system with a lattice chloroform molecule in 3d lead to luminescence quenching. Meanwhile, in the 4d dye, the intermolecular π-π interactions of pyridazine nitrogen atoms with the N-carbazolyl group of the adjacent molecule should facilitate intermolecular charge transfer (ICT) emission. Thus, the luminescence maxima for these dyes can be tuned across a broad range of 700–1100 nm by varying the number of chalcogen atoms, highlighting the potential for tailoring optical properties in optoelectronic applications.

This is a comprehensive overview on our research work to link interdisciplinary modeling and simulation techniques to improve the predictability and reliability simulations (PARs) of compressible turbulence with shock waves for general audiences who are not familiar with our nonlinear approach. This focused nonlinear approach is to integrate our “nonlinear dynamical approach” with our “newly developed high order entropy-conserving, momentum-conserving and kinetic energy-preserving methods” in the quantification of numerical uncertainty in highly nonlinear flow simulations. The central issue is that the solution space of discrete genuinely nonlinear systems is much larger than that of the corresponding genuinely nonlinear continuous systems, thus obtaining numerical solutions that might not be solutions of the continuous systems. Traditional uncertainty quantification (UQ) approaches in numerical simulations commonly employ linearized analysis that might not provide the true behavior of genuinely nonlinear physical fluid flows. Due to the rapid development of high-performance computing, the last two decades have been an era when computation is ahead of analysis and when very large-scale practical computations are increasingly used in poorly understood multiscale data-limited complex nonlinear physical problems and non-traditional fields. This is compounded by the fact that the numerical schemes used in production computational fluid dynamics (CFD) computer codes often do not take into consideration the genuinely nonlinear behavior of numerical methods for more realistic modeling and simulations. Often, the numerical methods used might have been developed for weakly nonlinear flow or different flow types other than the flow being investigated. In addition, some of these methods are not discretely physics-preserving (structure-preserving); this includes but is not limited to entropy-conserving, momentum-conserving and kinetic energy-preserving methods. Employing theories of nonlinear dynamics to guide the construction of more appropriate, stable and accurate numerical methods could help, e.g., (a) delineate solutions of the discretized counterparts but not solutions of the governing equations; (b) prevent numerical chaos or numerical “turbulence” leading to FALSE predication of transition to turbulence; (c) provide more reliable numerical simulations of nonlinear fluid dynamical systems, especially by direct numerical simulations (DNS), large eddy simulations (LES) and implicit large eddy simulations (ILES) simulations; and (d) prevent incorrect computed shock speeds for problems containing stiff nonlinear source terms, if present. For computation intensive turbulent flows, the desirable methods should also be efficient and exhibit scalable parallelism for current high-performance computing. Selected numerical examples to illustrate the genuinely nonlinear behavior of numerical methods and our integrated approach to improve PARs are included.

One of the most effective ways to investigate quark–gluon plasma (QGP) properties is to measure the azimuthal particle anisotropy in momentum space. This anisotropy can be characterized by the elliptic flow (). The evolution of the elliptic flow can be studied by using these two approaches: either measure values in different collision systems or use different particles of interest. Varying collision systems allows to investigate the impact of initial conditions on values. Also, using small-system collisions provides the opportunity to measure values in low multiplicity regions, where the conditions for QGP formation may be unachievable. Neutral pion is considered a unique tool to study development mechanisms, because its yields are measurable up to large transverse momenta () in small and large collision systems, where different effects of development can dominate. This work is dedicated to the measurement of the values for mesons as a function of and centrality in small collision system—He Au, and the largest collision system at RHIC—U U.

The chemical composition and properties of surface soil horizons (0–10 cm) and PM10 fractions were studied in three cities of northern Western Siberia (Novy Urengoy, Nadym, and Noyabrsk). The content of Al, Fe, Sc, V, Cr, Co, Ni, Cu, Zn, As, Sr, Mo, Sn, Sb, Cs, Ba, W, Pb, Bi, and U are determined by atomic emission spectrometry and inductively coupled plasma mass spectrometry. The average content of potentially toxic elements in urban soils is shown to be lower as compared with the element abundances in the Earth’s upper crust. The concentrations of Pb, Zn, Sb, and Sn in PM10 particles are 4–16-fold higher than the total content in soils. In Novy Urengoy, PM10 particles are enriched with Sb and Zn; in Nadym, with Sb, Zn, Pb, Ni, Cu, and V; and in Noyabrsk, with Sb, Zn, Ni, Pb, and Cu. Wider associations of pollutants are identified based on the EF (enrichment factor) values of the elements in PM10 particles. W, As, Sn, Bi, Mo, and Cu appear in the pollution profile. In all cities, Sb and Zn display the highest EF values. The most contrasting Sb anomalies are characteristic of road intersections and transport infrastructure facilities. According to the total EF, urban soils have an intermediate level of pollution versus the PM10 particles, polluted at a high level with Ni, Zn, W, and Cu as the key contributors. The main sources of elements are identified by the principal component analysis. The formation of the Ni–Co–Cr–W association is associated with lithogenic component and the Ba–Pb–Cs association, with organic matter. Characteristic of all cities is the accumulation of Zn, Sb, Cu, Pb, and Mo, the association that indicates a key role of motor vehicles in the contamination of urban soils.

AbstractThe wear resistance of DI37-VI and EK80-VI steel is studied using a friction testing device. A sample made of high-carbon chromium-vanadium steel relative to pellets made of MS221, VK3M, and VK6OM hard alloys on this device carries out reciprocating motion at a rate of 0.1 m/s. The base friction path is 50 km and the average temperatures of the samples are 100, 140, and 190°C . The effect of an average temperature of the samples on the wear resistance of DI37-VI and EK80-VI steel is described.

Reducing the deformation temperature is an important research task for superplastic forming of Ti-based alloys. This study demonstrates that the additions of Fe and B significantly improve microstructural homogeneity and superplastic performance, increase the post-forming mechanical strength, and reduce the superplastic deformation temperature of a Ti-Al-Mo-V alloy. The designed alloy exhibits an excellent superplastic deformation behavior with elongation of 590 to 1050 pct at 675 °C to 775 °C with a constant strain rate in a range of 5 × 10−4 to 5 × 10−3 s−1, and a high room temperature yield strength of 1020 MPa, a UTS of 1080 MPa, and elongation-to-failure of about 6 pct both after annealing and after superplastic deformation with a strain of 0.69 at 775 °C. The microstructure and the strain-induced changes in the size and shape of grains are discussed. The modification of the β-phase morphology leads to an increase in the curvature of interphase boundaries in the modified alloy. Advanced superplasticity and improved mechanical properties make the studied alloy a very attractive material for complex parts in numerous advanced applications.

Proton production have been preivously measured in PHENIX experiment in Au+Au collisions at sNN=200GeV. It was obtained that protons yields are enhanced over all mesons yields. This phenomenon was called \"baryon puzzle\". This paper presents mesurements of protons in asymmetric Cu+Au collisions at sNN=200GeV in order to investigate influence of collision geometry. Results in Cu+Au and Au+Au systems were found to be in agreement at similar number of participants, which might indicate that proton production in heavy-ion collision scales with the average size of the nuclear overlap region and do not depends on the details of its shape. ln order to investigate influence of quark content on production of protons consisting of three quarks comparison with φ, π0 -mesons (quark-antiquark pairs) was provided in Cu+Au collisions at the collision energy of 200 GeV. Such information can improve our understanding of quark-gluon plasma and recombination model.

Superplastic forming is a process that enables the production of complex-shaped parts using metallic alloys. To design the optimal forming regimes and ensure the success of forming operations, it is essential to use mathematical models that accurately represent the superplastic deformation behavior. This paper is concerned with the study of the microstructure and superplastic deformation behavior, with the construction of a constitutive model, of Al-Mg-Zn-Cu-Zr aluminum alloys with varying Ni contents. The aluminum solid solution and coarse precipitates of the T(Mg32(Al,Zn)49 and Al3Ni second phases were formed in the studied alloy and Cu dissolved in both second phases. The deformation behavior was investigated in the temperature range of 400–480 °C and the strain rate range of 10−3–10−1 s−1. Due to the fine Al3Zr precipitates, the alloys exhibit a partially recrystallized grain structure before the onset of superplastic deformation. Coarse precipitates of the second phases facilitate dynamic recrystallization and enhance superplasticity at the strain rates and temperatures studied. The alloys with ~6–9% particles exhibit high-strain-rate superplasticity at temperatures of 440–480 °C and strain rates of 10−2–10−1 s−1. The presence of high fractions of ~9% Al3(Ni,Cu) and ~3% T-phase precipitates provided high-strain-rate superplasticity with elongations of 700–800% at a low temperature of 400 °C. An Arrhenius-type constitutive model with good agreement between the predicted and experimental flow stresses was developed for the alloys with different Ni contents.