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High quality large single crystals of metal halide perovskites for optoelectronic applications

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Science China Chemistry 2017年第10期60卷 1326-1327页

作者： eugene A.Katz Alexandre Yersin Department of Solar Energy and Environmental Physics J. Blaustein Institutes for Desert Research Ben-Gurion University of the Negev Sede Boqer Campus 8499000 Israel Ilse-Katz Institute for Nanoscale Science and Technology Ben-Gurion University of the Negev Beer Sheva 8410501 lsrael

As the technological development of large single-crystalline wafers have revolutionized many industries including electronics and photovoltaics,one can predict that the availability of large single-crystalline perovskite crystals and wafers can revolutionize its broad applications in photodetectors,solar cells,LEDs,lasers,*** 2015,Liu et al.

关键词： crystalline halide perovskite technological electronics inverse optoelectronic wafer availability render

Alternative kind of hydrogen atoms as a possible explanation for the latest puzzling observation of the 21 cm radio line from the early Universe

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Research in Astronomy and Astrophysics 2020年第7期20卷 172-176页

作者： eugene Oks Physics Department 380 Duncan DriveAuburn UniversityAuburnAL 36849USA

There is a puzzling astrophysical result concerning the latest observation of the absorption profile of the redshifted radio line 21 cm from the early Universe(as described in Bowman et al.). The amplitude of the profile was more than a factor of two greater than the largest predictions. This could mean that the primordial hydrogen gas was much cooler than expected. Some explanations in the literature suggested a possible cooling of baryons either by unspecified dark matter particles or by some exotic dark matter particles with a charge a million times smaller than the electron charge. Other explanations required an additional radio background. In the present paper, we entertain a possible different explanation for the above puzzling observational result: the explanation is based on the alternative kind of hydrogen atoms(AKHA),whose existence was previously demonstrated theoretically, as well as by the analysis of atomic experiments. Namely, the AKHA are expected to decouple from the cosmic microwave background(CMB) much earlier(in the course of the Universe expansion) than usual hydrogen atoms, so that the AKHA temperature is significantly lower than that of usual hydrogen atoms. This seems to lower the excitation(spin) temperature of the hyperfine doublet(responsible for the 21 cm line) sufficiently enough for explaining the above puzzling observational result. This possible explanation appears to be more specific and natural than the previous possible explanations. Further observational studies of the redshifted 21 cm radio line from the early Universe could help to verify which explanation is the most relevant.

关键词： Cosmology:Early Universe explanation of the puzzle of 21cm radio line Galaxies:intergalactic medium Cosmology:observations Cosmology:theory

Galactic Dark Matter Halos Containing H Ⅰ Regions:A Possible Overestimation of the Column Densities

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Research in Astronomy and Astrophysics 2023年第3期23卷 100-103页

作者： eugene Oks Physics Department Auburn UniversityAuburnAL 36849USA

We analyze how the column density of hydrogen atoms in the HⅠregions,observed in dark matter halos of a number of galaxies,can be *** we study how the determination of the column density of hydrogen atoms from the observed astrophysical data would be affected by the possible presence of the Second Flavor of Hydrogen Atoms(SFHA),whose existence had been previously demonstrated in four different types of atomic experiments and had helped in explaining two puzzling astrophysical observations:the anomalous absorption in the 21 cm line from the early Universe and the smoother,less clumpy distribution of dark matter in the Universe than predicted by Einstein’s *** a model example we demonstrate that the neglect of the SFHA leads to the overestimation of the column density of hydrogen atoms in dark matter halos by about 30%.We perform these relatively simple estimates just to get the message across and to motivate further corresponding theoretical and experimental studies.

关键词： galaxies anomalous estimation

DES map shows a smoother distribution of matter than expected:a possible explanation

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Research in Astronomy and Astrophysics 2021年第10期21卷 1-4页

作者： eugene Oks Physics Department 380 Duncan DriveAuburn UniversityAuburnAL 36849USA

The largest and most detailed map of the distribution of dark matter in the Universe has been recently created by the Dark Energy Survey(DES)*** distribution was found to be slightly(by a few percent)smoother and less clumpy than predicted by general *** result was considered as a hint of some new physical *** the present paper we offer a relatively simple model that could explain the above result without resorting to any new physical *** model deals with the dynamics of a system consisting of a large number of gravitating neutral particles,whose mass is equal to the mass of hydrogen *** central point of the model is a partial inhibition of the gravitation for a relatively small subsystem of the entire *** would be sufficient for this subsystem to constitute just about a few percent of the total ensemble of particles for explaining the few percent more smooth distribution of dark matter(observed by the DES team)compared to the prediction of general *** most viable candidate for the dark matter particles in this model is the second flavor of hydrogen atoms(SFHA)that has only S-states and therefore does not couple to the electric dipole radiation or even to higher multipole radiation,so that the SFHA is practically *** SFHA has experimental confirmation from atomic experiments,it does not go beyond the Standard Model,it is based on standard quantum mechanics and it explains puzzling astrophysical observations of the redshifted line 21 cm from the early ***,our model explaining the DES result of a little too smooth distribution of dark matter without resorting to any new physical laws seems to be self-consistent.

关键词： (cosmology:)dark matter gravitation atomic processes astroparticle physics

Reminiscing my sixty year pursuit of the physics of the Sun and the Galaxy

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Research in Astronomy and Astrophysics 2014年第1期14卷 1-14页

作者： eugene N.Parker Department of Physics Department of Astronomy and AstrophysicsUniversity of Chicago

Reminiscing begins with childhood and passes on to student days through graduate school and the first real contact with research. Then early academic posi- tions and stumbling efforts to pursue my ideas. The first significant progress came as a research associate with Prof. W. M. Elsasser at the University of Utah, beginning with an introduction to magnetohydrodynarnics and the generation of the geomagnetic field through induction in the liquid metal core of Earth. A move to the University of Chicago to work with Prof. J. A. Simpson, on the implications of cosmic ray varia- tions and interplanetary magnetic fields, led to the theory of coronal expansion and the solar wind and then to exploring the dynamical effects of cosmic rays on the galactic magnetic field. Spontaneous current sheets and intrinsic rapid reconnection in interlaced magnetic field line topologies were the next big project, leading up to retirement. Finally, it is a pleasure to recall my many associates, whose fresh thinking helped stimulate the daily research activities.

关键词： dynamo -- magnetohydrodynamics -- plasma

A practical geometrical comparison between free-repelled hydraulic jumps within inclined channels

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Science China(Technological Sciences) 2009年第11期52卷 3363-3367页

作者： John Demetriou eugene Retsinis National Technical University of Athens School of Civil Engineering. JD Research Hydrolab-A non Profit Foundation 12 Polykarpou St. N. Smymi Athens 17123 Greece National Technical University of Athens School of Civil Engineering. 23 Loid Tzortz St. Athens 11744 Greece

In this experimental study a practical geometrical comparison between inclined (angle φ) free and repelled hydraulic jumps (the latter in non prismatic but abruptly expanding channels) is presented, analysed and discussed. For repelled hydraulic jumps a considerable parameter is the expansion ratio r (=channels' width ratio), which here is changing from r =0.5 to r =0.7. The comparison is made with the free jump (in prismatic channel, r =1), in the same ranges of angles φ (0°≤φ≤8°) and Froude numbers (2≤Fr1≤8). A practical arithmetic example is presented to show the behavioral change of conjugate depths, lengths L and depths at 0.5L, in order to receive a comparison among all pertinent geometrical quantities. The present results may be useful for the hydraulic engineering when designing open channels.

关键词： free jumps repelled jumps inclined channels

Preservation of Linear Constraints in Approximation of Tensors

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Numerical Mathematics(Theory,Methods and Applications) 2009年第4期2卷 421-426页

作者： eugene Tyrtyshnikov Institute of Numerical Mathematics of Russian Academy of Sciences

For an arbitrary tensor(multi-index array) with linear constraints at each direction,it is proved that the factors of any minimal canonical tensor approximation to this tensor satisfy the same linear constraints for t... 详细信息

关键词： Multi-index arrays tensors linear constraints low rank approximation canonicaltensor decomposition multilevel matrices.

Age and chemical composition of the globular cluster NGC 6652

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Research in Astronomy and Astrophysics 2020年第8期20卷 252-260页

作者： Margarita eugene Sharina Vladislav Vladimirovich Shimansky Special Astrophysical Observatory Russian Academy of SciencesNizhnii Arkhyz369 l67Russia Kazan Federal University 18 Kremlyovskaya streetKazan420008Russia

We present the results of determination of the age,helium mass fraction(Y),metallicity([Fe/H]),and abundances of the elements C,N,O,Na,Mg,Ca,Ti,C and Mn for the Galactic globular cluster NGC *** use its medium-resolution integrated-light spectrum from the library of Schiavon and our population synthesis method to fulfill this *** select the evolutionary isochrone and stellar mass function for our analysis,which provide the best approximation to the shapes and intensities of the observed Balmer line *** determined elemental abundances,age and metallicity are characteristic of stellar populations in the Galactic Bulge.

关键词： globular clusters:general globular clusters:abundances globular clusters:individual:NGC 6652

Spontaneous Recovery in Directed Dynamical Networks

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Engineering 2024年第6期37卷 208-214页

作者： Xueming Liu Xian Yan H.eugene Stanley School of Artificial Intelligence and Automation&The MOE Engineering Research Center of Autonomous Intelligent Unmanned Systems&the Key Laboratory of Image Processing Huazhong University of Science and TechnologyWuhan 430074China Center for Polymer Studies Department of PhysicsBoston UniversityBostonMA 02215USA

Complex networked systems,which range from biological systems in the natural world to infrastructure systems in the human-made world,can exhibit spontaneous recovery after a failure;for example,a brain may spontaneously return to normal after a seizure,and traffic flow can become smooth again after a *** studies on the spontaneous recovery of dynamical networks have been limited to undirected ***,most real-world networks are *** fill this gap,we build a model in which nodes may alternately fail and recover,and we develop a theoretical tool to analyze the recovery properties of directed dynamical *** find that the tool can accurately predict the final fraction of active nodes,and the prediction accuracy decreases as the fraction of bidirectional links in the network increases,which emphasizes the importance of directionality in network *** to different initial states,directed dynamical networks may show alternative stable states under the same control parameter,exhibiting hysteresis *** addition,for networks with finite sizes,the fraction of active nodes may jump back and forth between high and low states,mimicking repetitive failure-recovery *** findings could help clarify the system recovery mechanism and enable better design of networked systems with high resilience.

关键词： Network resilience Directed dynamical networks Spontaneous recovery