Local electron mean energy profile of positive primary streamer discharge with pin-plate electrodes in oxygen nitrogen mixtures

Local electron mean energy （LEME） has a direct effect on the rates of collisional ionization of molecules and atoms by electrons. Electron-impact ionization plays an important role and is the main process for the production of charged particles in a primary streamer discharge. Detailed research on the LEME profile in a primary streamer discharge is extremely important for a comprehensive understanding of the local physical mechanism of a streamer. In this study, the LEME profile of the primary streamer discharge in oxygen-nitrogen mixtures with a pin-plate gap of 0.5 cm under an impulse voltage is investigated using a fluid model. The fluid model includes the electron mean energy density equation, as well as continuity equations for electrons and ions and Poisson＇s electric field equation. The study finds that, except in the initial stage of the primary streamer, the LEME in the primary streamer tip tends to increase as the oxygen-nitrogen mole ratio increases and the pressure decreases. When the primary streamer bridges the gap, the LEME in the primary streamer channel is smaller than the first ionization energies of oxygen and nitrogen. The LEME in the primary streamer channel then decreases as the oxygen-nitrogen mole ratio increases and the pressure increases. The LEME in the primary streamer tip is primarily dependent on the reduced electric field with mole ratios of oxygen-nitrogen given in the oxygen-nitrogen mixtures.

Quasi-40-Day Oscillation and Its Teleconnection Structure together with the Possible Dependence on Conversion of Barotropic Unstable Energy of Temporal Mean Flow

A study is made of the distribution of the diagnostic quantity vector E and the teleconnection structure of 30-50 (quasi-40) day oscillation, together with the dependence on the conversion of barotropic unstable energy of mean flow in terms of ECWMF daily 500 hPa grid data in winter, indicating that the energy transportation is closely associated with the westerly jet position, with zonal (meridional) propagation in the strong (weak) wind region, that considerable conversion of barotropic energy occurs at the jet exit region where low-frequency oscillation gains energy from the mean flow, leading to maximum kinetic energy for the oscillation observed there, which is marked by evident barotropy in striking contrast to the baroclinicity at low latitudes and that the teleconnection core is related to the center of action in the atmosphere and bound up with the pattern of the west wind.

Water Manipulation through Curvature Energy on Humidity Microparticles

The electric field created in a curvature energy sensor on air microparticles is used to obtain a temperature-humidity map G:M→SO(2)∪F,by stereo-radially of the sensor design to detect and measure the temperature and humidity of certain local region of the environment space.Likewise,considering the curvature energy as the deviation of any field interaction,even the obstruction to its proper flow,is designed and created a humidity-resistor sensor to the control and optimization of humidity in a space with different gradients of humidity,pressure and temperature in a radial detection and measuring.Then the sensing problem is a problem of free boundary conditions where is satisfied an energy functional of norm ||ξ||_(2),to curvature functions κ,that satisfy in the temperature and humidity function ξ,the change limit condition ξ|_(∂Ω)≤2πξ(r).This carries to that the temperature-humidity sensor must be designed on a length gauge to measure the changes of humidity and temperature in the space.

Secondary electron emission model for photo-emission from metals in the vacuum ultraviolet

This study investigates two secondary electron emission(SEE)models for photoelectric energy distribution curves f(E_(ph),hγ),B,E_(mean),absolute quantum efficiency(AQE),and the mean escape depth of photo-emitted electronsλof metals.The proposed models are developed from the density of states and the theories of photo-emission in the vacuum ultraviolet and SEE,where B is the mean probability that an internal photo-emitted electron escapes into vacuum upon reaching the emission surface of the metal,and E_(mean)is the mean energy of photo-emitted electrons measured from vacuum.The formulas for f(E_(ph),hγ),B,λ,E_(mean),and AQE that were obtained were shown to be correct for the cases of Au at hγ=8.1–11.6 eV,Ni at hγ=9.2–11.6 eV,and Cu at hγ=7.7–11.6 eV.The photoelectric cross sections(PCS)calculated here are analyzed,and it was confirmed that the calculated PCS of the electrons in the conduction band of Au at hγ=8.1–11.6eV,Ni at hγ=9.2–11.6 eV,and Cu at hγ=7.7–11.6 eV are correct.

On two distinct Reynolds number regimes of a turbulent square jet

The effects of Reynolds number on both large-scale and small-scale turbulence properties are investigated in a square jet issuing from a square pipe. The detailed velocity fields were measured at five different exit Reynolds numbers of 8 × 10^3 〈 Re 〈 5 × 10^4. It is found that both large-scale properties （e.g,, rates of mean velocity decay and spread） and small-scale properties （e.g., the dimensionless dissipation rate constant A = εL/（u^2）^3/2） are dependent on Re for Re ≤ 3 ×10^4 or Reλ ≤ 190, but virtually become Re-independent with increasing Re or Reλ. In addition, for Reλ 〉 190, the value ofA = εL/（u^2）^3/2 in the present square jet converges to 0.5, which is consistent with the observation in direct numerical simulations of box turbulence, but lower than that in circular jet, plate wake flows, and grid turbulence. The discrepancies in critical Reynolds number and A = εL/（u^2）^3/2 among different turbulent flows most likely result from the flow type and initial conditions.

Ion stopping in dense plasmas: A basic physics approach

We survey quite extensively the present research status of ion-stopping in dense plasmas of potential importance for initial confinement fusion(ICF)drivenby intense and heavy ion beams,and alsofor warm dense matter(WDM).First,we putemphasis on every possible mechanism involved in the shaping of the ion projectile effective charge,while losing energy in a target plasma with classical ions and partially degenerate electrons.Then,we switch to ion stopping by target bound electrons,taking detailed account of mean excitation energies.Free electron stopping has already been given a lot of attention in former works[C.Deutsch et al.,Recent Res.Devel.Plasma 1(2000)1-23;Open Plasma Phys.J.3(2010)88-115].Then,we extend the usual standard stopping model(SSM)framework to nonlinear stopping including a treatment of the Z 3 Barkas effect and a confronting comparison of Bloch and Bohr Coulomb logarithms.Finally,we document low velocity ion slowing down(LVISD)in single ion plasmas as well as in binary ionic mixtures(BIM),in connection with specific ICF fuels.

Dynamics of supercooled confined water measured by deep inelastic neutron scattering

In this paper, we present the results of deep inelastic neutron scattering （DINS） measurements on supercooled water confined within the pores （average pore diameter - 20A） of a disordered hydrophilic silica matrix obtained through hydrolysis and polycondensation of the alkoxide precursor Tetra-Methyl- Ortho-Silicate via the sol-gel method. Experiments were performed at two temperatures （250 K and 210 K, i.e., before and after the putative liquid-liquid transition of supercooled confined water） on a ＂wet＂ sample with hydration h -40% w/w, which is high enough to have water-filled pores but low enough to avoid water crystallization. A virtually ＂dry＂ sample at h - 7% was also investigated to measure the contribution of the silica matrix to the neutron scattering signal. As ：is well known, DINS measurements allow the determination of the mean kinetic energy and the momentum distribution of the hydrogen atoms in the system and therefore, allow researchers to probe the local structure of supercooled confined water. The main result obtained is that at 210 K the hydrogen mean kinetic energy is equal or even slightly higher than at 250 K. This is at odds with the predictions of a semi-empirical harmonic model recently proposed to describe the temperature dependence of the kinetic energy of hydrogen in water. This is a new and very interesting result, which suggests that at 210 K, the water hydrogens experience a stiffer intermolecular potential than at 250 K. This is in agreement with the liquid-liquid transition hypothesis.

Fundamental study on mixing layer and horizontal circulation in open-channel flows with rectangular embayment zone

A part of mean kinetic energy in a main-channel is used for production of a large-scale horizontal circulation in the side cavity. However, the details of the mechanism such as energy transport are poorly understood. Therefore, we conducted PIV mea- surements in a laboratory flume and compared space distributions of mean velocity components and Reynolds stress by varying a cavity geometry. In particular, a practical calculation method of Reynolds stress was also developed and its accuracy was examined by comparison with the measured data. Furthermore, contributions of components in an energy transport equation were revealed quantitatively.

Stability of super heavy nuclei associated with the updated nuclear data

The stability of super heavy nuclei（SHN） from Z =104 to Z =126 is analyzed systematically,associated with the following theoretical mass tables： FRDM2012 [At.Data Nucl.Data Tables 109-110（2016）],WS2010 [Phys.Rev.C 82,044304（2010）],WS-LZ-RBF [J.Phys.G： Nucl.Part.Phys.42,095107（2015）] and the updated experimental data AME2016 [Chinese Physics C 41,040002（2017）].The nucleus with the biggest mean binding energy in each isotopic chain shows systematic regular behavior,indicating that the mean binding energy is a good criterion to classify SHN by their stability.Based on binding energy,the α-decay energy Qα,two-proton separation energy S2p,and two-neutron separation energy S2n are extracted and analyzed.It is found that N =152 and N =162 are sub-magic numbers,N = 184 is a neutron magic number,and Z = 114 is a proton magic number,which may provide useful information for the synthesis and identification of SHN.

Coordinated adaptive beamformer over distributed antenna network

The spatial diversity of distributed network demands the individual filter to accommodate the topology of interference environment. In this paper, a type of distributed adaptive beamformer is proposed to mitigate interference over coordinated antenna arrays network. The proposed approach is formulated as generalized sidelobe canceller （GSC） structure to facilitate the convex combination of neighboring nodes＇ weights, and then it is solved by unconstrained least mean square （LMS） algorithm due to simplicity. Numerical results show that the robustness and convergence rate of antenna arrays network can be significantly improved in strong interference scenario. And they also clearly illustrate that mixing vector is optimized adaptively and adjusted according to the spatial diversity of the distributed nodes which are placed in different power of received signals to interference ratio （SIR） environments.