Drift loss cone instability in the ring current and plasma sheet

The drift loss cone instability, propagating nearly transverse to the ambient magnetic field, is studied in the ring current plasma taking into account the relative driftU between electrons and protons due to density gradients. The growth rates attain maxima and then decrease as the wave number parallel to the magnetic fieldk _II increases. The peak values of the growth rates, maximised with respect tok _II, are enhanced by the increase in number density, electron temperature and loss cone index, and by the decrease in β_t, the ratio of the proton thermal pressure to magnetic field pressure. The unstable frequencies fall in the range of 5 to 30Ω_p with the growth rate γ ≥Ω_p. In the ring current region betweenL=4 and 5, the instability will generate a strong turbulence in the frequency range between 5–500 Hz which can produce fluctuating electric fields 0. 5–5 mV/m and magnetic field 0.8–80mγ. This instability can also occur on the auroral field lines, which connect to the region of intense earthward plasma flow in the distant magnetotail and produce a broad band electrostatic noise.     

Pre-flare changes in the turbulence regime for the photospheric magnetic field in a solar active region

Observations of the total magnetic field in the active region NOAA 6757 have been used to study the turbulence regime from 2.5 h before the onset of a 2B/X1.5 flare until two minutes after its maximum. The curvature of the exponent ζ(q) for the structure functions of the B _z field increases monotonically before the flare (i.e., the multifractal character of the B _z field becomes more complex) but straightens at the flare maximum and coincides with a linear Kolmogorov dependence (implying a monofractal structure for the B _z field). The observed deviations of ζ(q) from a Kolmogorov line can be used for short-term forecasting of strong flares. Analysis of the power spectra of the B _z field and the dissipation of magnetic-energy fluctuations shows that the beginning of the flare is associated with the onset of a new turbulence regime, which is closer to a classical Kolmogorov regime. The scaling parameter (cancellation index) of the current helicity of the magnetic field, k _h , remains at a high level right up until the last recording of the field just before the flare but decreases considerably at the flare maximum. The variations detected in the statistical characteristics of the turbulence can be explained by the formation and amplification of small-scale flux tubes with strong fields before the flare. The dissipation of magnetic energy before the flare is primarily due to reconnection at tangential discontinuities of the field, while the dissipation after the flare maximum is due to the anomalous plasma resistance. Thus, the flare represents an avalanche dissipation of tangential discontinuities.     

Observations of the electric fields that accelerate auroral particles

Electric fields accelerate electrons and ions in the auroral zone at altitudes below 8000 km to produce several distinctive particle distributions. The electric field of electrostatic shocks and double layers produces the inverted-V precipitating electron and up-flowing ion beams. Electrostatic ion cyclotron waves heat ion beams. The electric field in low frequency plasma waves and electrostatic shocks produces ion conics and field-aligned or counterstreaming electrons. Relationships between electric fields and particle distributions are illustrated with data from the S3-3 satellite.     

Solar MHD turbulence in regions with various levels of flare activity

The paper continues investigations of MHD turbulence in active solar regions. The statistical distributions of the increments (structure functions) of the turbulent field are studied analytically in the context of a refined Kolmogorov theory of turbulence. Since photospheric transport of the B _z component of the magnetic field is quite similar to that of a scalar field in a turbulent flow, the theory of transport of a passive scalar can be applied. This approach enables us to show that the structure functions are determined by the competition between the dissipation of the magnetic and kinetic energies and to obtain a number of relations between the structure-function parameters and energy characteristics of the MHD turbulence. Taking into account general conclusions that can be drawn on the basis of the refined Kolmogorov turbulence theory, the structure functions of the B _z field are calculated for eight active regions (from measurements of SOHO/MDI and the Huairou Solar Observing Station, China). These calculations show that the behavior of the structure functions is different for the B _z field of each active region. The energy-dissipation index of the fluctuation spectrum (which is uniquely determined by the structure functions) is closely related to the level of flare activity: the more activity, the less steep the dissipation spectrum for a given active region. This provides a means to test and, consequently, forecast the flare activity of active regions.     

A geophysical, geochemical, petrological model of the sub-marine lithosphere

A schematic but quantitative geochemical, petrological, model of the sub-marine lithosphere and its genesis is given. With this model we calculate numerically, a priori, the geophysical characteristics of the lithosphere, its acoustic properties, density, oceanic heat flow and ocean bottom topography. Comparison with observational data for these characteristics shows good agreement. Particular attention is given to anomalous upper mantle in the vicinity of spreading centres. Compressional and shear wave velocity distributions are given in tabular form for the submarine lithosphere as a function of age. Comparison between observations for V_p, V_s and the calculated acoustic properties suggests that the lower marine lithosphere is anisotropic. Possible thickening of layer 3 with age is discussed. Melt distribution in the ridge axial region has been evaluated. All calculations were done for a plate velocity of 1 cm y⁻¹.     

Hochtemperatur-Plagioklas im Meteorit von Oldenburg

Zusammenfassung Der Plagioklas im Meteorit von Oldenburg (10. 9. 1930) zeigt Hochtemperaturoptik, die damit auch für weitere Chondrite wahrscheinlich ist. Zusammensetzung ist An₁₁, 2V = 60 1/2°, = 1,5365, Auslöschungsschiefe 7 1/2°, Winkel zwischen und der 0-Stelle der Auslöschung 24°, Winkel zwischen [001] und = 20°. Anteil 6%, Verzwillingung sehr eng nach dem Albit- und Periklingesetz. Die Indikatrix wird mit den bisherigen Werten für die Hochtemperaturoptik verglichen.     

Method for Estimating the Doppler Factors of Relativistic Radio Jets

An expression for the intensity of synchrotron emission from a radio source (in the optically thin regime) in terms of the energy densities in the magnetic field and particles is obtained, based on a definition of a relativistic electron related to its rest energy. A relationship is obtained between the energy densities in particles E_e and the magnetic field E_H for a physical system containing a magnetic field and relativistic electrons in a minimum-energy state. A method for estimating the Doppler factors of the relativistic electrons has been developed. This method does not requires that all radio sources have the same radiation energies (brightness temperatures): it is sufficient that the energies of the magnetic fields and relativistic particles in the source be approximately equal. The method yields Doppler-factor estimates with reasonably good accuracy, even when there are modest deviations from energy equipartition in the radio source,making it applicable to many radio sources. The method is used to estimate the Doppler factor of the radio jet in CTA 21.

     

Sources of the global magnetic field of the Sun

Data on the global magnetic field (GMF) of the Sun as a star for 1968–1999 are used to determine the correlation of the GMF with the radial component of the interplanetary magnetic field (IMF) |B _r|; all data were averaged over a half year. The time variations in the GMF |H| are better correlated with variations in |B _r|; than the results of extrapolating the field from the “source surface” to the Earth’s orbit in a potential model based on magnetic synoptic maps of the photosphere. Possible origins for the higher correlation between the GMF and IMF are discussed. For both the GMF and IMF, the source surface actually corresponds to the quiet photosphere—i.e., background fields and coronal holes—rather than to a spherical surface artificially placed ≈2.5 R _⊙ from the center of the Sun, as assumed in potential models (R _⊙ is the solar radius). The mean effective strength of the photospheric field is about 1.9 G. There is a nearly linear dependence between |H| and |B _r|. The strong correlation between variations in |H| and |B _r| casts doubt on the validity of correcting solar magnetic fields using the so-called “saturation” factor δ^?1 (for magnetograph measurements in the λ 525.0 nm FeI line).     

CSAMT测量中磁场对测量结果的影响

CSAMT的标量测量中常采用共磁道测量方式,即同步观测测量剖面上多个电道信号和垂直测量剖面的一个磁道信号,由此计算各测点的Cagniard视电阻率。因磁场测量位置的不同,势必对测量结果产生影响。计算了均匀半空间条件下不同测量位置的磁场强度,以及对视电阻率的影响;模拟了存在局部三维异常体时,赤道装置下不同位置的磁场对视电阻率的影响。结合野外实测资料分析认为,由磁场测量位置偏差引起的视电阻率误差难以校正,在实际工作中应尽量采用单电单磁的测量方式;当在大收发距且浅层电性结构单一的条件下,可以采用三电一磁的测量方式。研究对CSAMT标量测量方式的改进及实际勘查工作具有一定的指导意义。      

Impact of internal waves on the acoustic field at a coastal station off Paradeep,east coast of India

Internal Wave (IW) characteristics and the impact of IW on acoustic field have been studied utilizing the hourly time series of temperature and salinity data collected at a coastal site off Paradeep (north Bay of Bengal) during 24–25 October 2008. The IW characteristics, viz. period (t _per ), velocity (C _vel ), wavelength (L), and wave numbers (k), are found to be 2.133–34.72 h, 0.135 km h⁻¹, 0.37–6.2 km and 2.70–0.16 cycles km⁻¹, respectively. The semi-diurnal tidal forces are predominant than diurnal as well as at other frequencies and its contribution is about 64% towards the total potential energy (E ₀ = 3.34 J m⁻²). Sound velocity perturbations with space and time in the presence of IW field are examined from Garrettt-Munk (GM) model. Transmission loss anomaly for optimized source-receiver configuration at the depth of 53 m and range of 9 km has been computed from acoustic modelling. The loss in the acoustic transmission is found to be 38.4 dB in the presence of low-frequency IW field.     

Large-scale stratification of the ionosphere during earthquake preparation

Modulation of ionospheric plasma density by acoustic waves (AW) is investigated. A rigorous electrodynamic model of the interaction of acoustic waves, generated by the lithospheric displacements during the seismic event preparation, with the cold dense ionospheric plasma in the presence of a magnetic field is constructed in conjunction with the actual height variations of the plasma particles' mobility and conductivity tensors in the ionosphere. A mechanism of creation of ionospheric inhomogeneities with different scales and with various degree of disturbance ΔN/N₀=10⁻⁴–10⁻⁵ (N₀ is the concentration of plasma electrons (ions) in background ionospheric plasma) is presented.     

Effect of attachment configuration on the trapping efficiency of Vaseline-coated slide catchers for windblown particles

There are various types of the windblown sediment traps developed for wind tunnel and field studies. One of the main supports expected from these traps is in measuring surface dust concentrations to appropriately derive flux equations. The measurement performance and accuracy of a trap is very important and depends strictly upon the physical characteristics and the behaviors of dust grains with air flows. This paper presents the measurement results of static pressure distribution (SPD) of wind flow around Vaseline-coated slide (VCS) catchers with an aim of finding out whether or not particle trapping efficiency (η) of the VCS is related to the SPD. The SPD was evaluated by a wind reduction coefficient (R _c) in a series of wind tunnel experiments with different VCS settings which have different attachment configurations on a pole. Three VCS configurations were considered: a configuration on a circular plastic pole (CPP) and two configurations on wooden square poles (WSP₁ and WSP₂, respectively). Thus, the primary contribution of this work was to experimentally analyze the effect of the different attachment configurations on the SPD, and the secondary objective was to determine the effect of the SPD on the η. It was shown that spatial correlation and spatial pattern of the R _c were different in the surrounding area of each configuration, and ANOVA and DUNCAN tests indicated that η(s) of WSP₁, WSP₂, and CPP were different at the significant level of P ≤ 0.05 with the mean of 0.94 ± 0.09, 0.63 ± 0.14, and 1.13 ± 0.07, respectively. Additionally, the amount of PM₂₀, PM₄₀, PM₆₀, PM₈₀, and PM₁₀₀ trapped by the configurations of WSP₁, WSP₂, and CPP considerably varied depending upon the particular aerodynamic circumstances associated with every configuration.     

High-pressure phase of natural fullerene C60 in iridium-rich Cretaceous-Tertiary boundary layers of Deccan intertrappean deposits, Anjar, Kutch, India

We report here for the first time the presence of the natural, toluene-soluble C₆₀ and the toluene-insoluble high-pressure and temperature phase of fullerene C₆₀ in the carbonaceous matter extracted from the iridium-rich layers of the intertrappean sediments of Anjar, India. The toluene-insoluble form of fullerene is formed at high-temperature and pressure (HPT) and is distinguished from normal fullerene by UV-visible and Fourier-transform infrared (FT-IR) spectroscopic techniques. The C₆₀ fullerene has been identified by high-resolution electron-impact ionization mass spectrometric analysis, as well as by Fourier-transform infrared (FT-IR), UV-visible, and ¹³C-nuclear magnetic resonance (NMR) spectroscopy. In iridium-poor horizons of this section, fullerenes are absent, but complex hydrocarbons are sometimes present. The FT-IR spectroscopic studies on the insoluble fullerenes show strong absorption peaks at about 740 and 509 cm⁻¹ and a number of weak peaks at 1380, 1300, 1205, 1120, 1000, 608, 554, and 441 cm⁻¹, which are characteristic of a high-pressure and temperature C₆₀ fullerene. The UV-visible spectra of the toluene-soluble fullerene, as well as the insoluble fullerene, show strong absorption bands at 270 and 348 nm, which are characteristic of pristine fullerene C₆₀. The toluene-insoluble carbon-rich residue shows additional absorption bands at 710, 640, and 395 nm. These UV-visible bands independently confirm the presence of the high-pressure-temperature (HPT) phase of fullerene C₆₀. Conditions of high-pressure and temperature required for formation of the HPT fullerene phase can be created by an energetic impact event. Therefore, the presence of HPT fullerene in the KT boundary layer at Anjar is linked to the impact event at the KT transition.     

Practical Estimates of Tensile Strength and Hoek–Brown Strength Parameter m i of Brittle Rocks

By applying the Griffith stress criterion of brittle failure, one can find that the uniaxial compressive strength (σ_c) of rocks is eight times the value of the uniaxial tensile strength (σ_t). The Griffith strength ratio is smaller than what is normally measured for rocks, even with the consideration of crack closure. The reason is that Griffith’s theories address only the initiation of failure. Under tensile conditions, the crack propagation is unstable so that the tensile crack propagation stress (σ_cd)_t and the peak tensile strength σ_t are almost identical to the tensile crack initiation stress (σ_ci)_t. On the other hand, the crack growth after crack initiation is stable under a predominantly compressive condition. Additional loading is required in compression to bring the stress from the crack initiation stress σ_ci to the peak strength σ_c. It is proposed to estimate the tensile strength of strong brittle rocks from the strength ratio of R = \fracs_\textc | s_\textt | = 8\fracs_\textc s_\textci . R = {\frac{{\sigma_{\text{c}} }}{{\left| {\sigma_{\text{t}} } \right|}}} = 8{\frac{{\sigma_{\text{c}} }}{{\sigma_{\text{ci}} }}}. The term \fracs_\textc s_\textci {\frac{{\sigma_{\text{c}} }}{{\sigma_{\text{ci}} }}} accounts for the difference of crack growth or propagation in tension and compression in uniaxial compression tests. \fracs_c s_ci {\frac{{\sigma_{c} }}{{\sigma_{ci} }}} depends on rock heterogeneity and is larger for coarse grained rocks than for fine grained rocks. σ_ci can be obtained from volumetric strain measurement or acoustic emission (AE) monitoring. With the strength ratio R determined, the tensile strength can be indirectly obtained from | s_\textt | = \fracs_\textc R = \fracs_\textci 8. \left| {\sigma_{\text{t}} } \right| = {\frac{{\sigma_{\text{c}} }}{R}} = {\frac{{\sigma_{\text{ci}} }}{8}}. It is found that the predicted tensile strengths using this method are in good agreement with test data. Finally, a practical estimate of the Hoek–Brown strength parameter m _i is presented and a bi-segmental or multi-segmental representation of the Hoek–Brown strength envelope is suggested for some brittle rocks. In this fashion, the rock strength parameters like σ_t and m _i, which require specialty tests such as direct tensile (or Brazilian) and triaxial compression tests for their determination, can be reasonably estimated from uniaxial compression tests.     

Measurement of the inner turbulence scale of the interstellar plasma toward the pulsar PSR B2111+46

The pulsar PSR B2111+46 has been observed at 112 MHz, and a new approach to analyzing pulsar pulses scattered in turbulent interstellar plasma applied. This method is based on the dependence of the normalized energy in the trailing part of a pulse on the intrapulse time. Since the trailing edge of a pulse follow exponential law to high accuracy, the inner turbulence scale of the interstellar plasma exceeds the field coherence scale. The measured scattering parameter is τ _sc = 147 ± 1 ms. Analysis of the parameters of diffractive and refractive scintillations of the pulsar at 610 MHz together with the 112 MHz data shows that the spectrum of the interstellar plasma toward PSR B2111+46 is a piecewise power law: on scales of 10¹³–10¹⁴ cm, the exponent of the turbulence spectrum is n ≃ 4, whereas n = 3.5 on scales of 2 × 10⁸−10¹³ cm. The spectrum flattens with approach to the inner turbulence scale l: n = 3–3.2. The obtained inner turbulence scale is l = (3.5 ± 1.5) × 10⁷ cm. The distribution of the interstellar plasma toward the pulsar is close to statistically homogeneous. The local density (N _e = 0.4 cm⁻³) and filling factor (F = 0.04) of the interstellar plasma have been estimated. The similarity of N _e estimates obtained from the inner scale of the inhomogeneities and the ratio of the emission measure to the dispersion measure provides evidence that the inner turbulence scale corresponds to the ion inertial length.     

Electron acceleration in the ionosphere of Io

A mechanism for the acceleration of electrons in the ionosphere of Io due to the moon's motion through the Jovian magnetic field and the presence of Io's ionosphere is considered. Attention is drawn to the important role of the anisotropic conductivity of the ionosphere, which results in the formation of a longitudinal (with respect to the planetary magnetic field) component of the charge-separation electric field. Owing to this anisotropy, the electric field induced by the motion of Io, E_i, produces in Io's ionosphere not only a Pedersen electrical current along E_i but also a Hall current that is approximately perpendicular to the moon's surface in the “upstream” and “downstream” parts of the ionosphere. However, this current cannot be closed through the surface, leading to the formation of a powerful charge-separation field in Io's ionosphere. This field has a component parallel to the magnetic field, with an amplitude comparable to that of the induced electric field. Electron runaway along the magnetic field is also considered, and the occurrence of “active longitudes” and preferred locations for the sources of decametric radio emission in the northern hemisphere of Jupiter are interpreted. The characteristic energies and fluxes of the accelerated electrons injected into Io's flux tube are estimated. The energy of these electron fluxes is sufficient to produce the electromagnetic radiation observed from Io's magnetic tube.     

Monitoring of the radio emission of the Crab Nebula pulsar at low frequencies

Results of long-term (2002–2010) monitoring of giant radio pulses of the pulsar PSR B0531+21 in the Crab Nebula at ν = 44, 63, and 111 MHz are reported. The observations were conducted on the LPA and DKR-1000 radio telescopes of the Lebedev Physical Institute. The giant pulses were analyzed using specialized software for calculating the magnitude of the scattering τ _sc , signal-to-noise ratio, and other required parameters by modeling the propagation of a pulse in the scattering interstellar medium. Three pronounced sharp increases in the scattering were recorded in 2002–2010. Analysis of the dependence between the variations of the scattering and dispersion measure (data of Jodrell Bank Observatory) shows a strong correlation at all frequencies, ≈0.9. During periods of anomalous increase in scattering and the dispersion measure, the index γ in the frequency dependence of the scattering in the Crab Nebula, τ _sc (ν) ∝ ν ^−γ , was smaller than the generally accepted values γ = 4.0 for a Gaussian and γ = 4.4 for a Kolmogorov distribution. This difference in combination with the piece-wise power-law spectrum may be due to the presence of a dense plasma structure with developed Langmuir turbulence in the nebula, along the pulsar’s line of sight. The magnetic field in the Crab Nebula estimated from measurements of the rotation measure toward the pulsar is 100 μG.     

Introduction to pareto optimal mine planning

Summary Recent advances in mathematical optimization have resulted in the development of superior techniques for solving realistic decision making problems. The technique called PARETO OPTIMAL SERIAL DYNAMIC PROGRAMMING is presented here as a tool for rational mine planning. This approach always enables the identification of a set of decision alternatives considered superior to the remaining feasible, usually numerous, decision alternatives, when a number of conflicting, noncommensurable, objectives are simultaneously optimized. It is further noted that the decision makers' truly preferred decision is always one of the members identified as the superior set.Notation [A] Number of initial decision alternatives for production stage 1 - [A ] Accumulated pareto optimal stage objective vector at stage for the remainder of the stagesN – - [A] Accumulated non-pareto optimal stage objective vector at stage for the remainder of the stagesN – - [B] Number of initial decision alternatives for production stage 2 - [C] Number of initial decision alternatives for production stageN - [COG _k,] Cutoff grade for decision,k, at production stage, - [D] Number of initial pareto solutions for production stage 1 - [D ] Decision at stage - [E] Number of initial pareto solutions for production stage 2 - [F] Number of initial pareto solutions for production stageN - [j] A random objective function - [J] Number of objective functions - [LIFE _k,] Minelife for decision,k, at production stage, - [] An arbitrary production stage - [N] Final production stage - [NPV] Expected net present value - [NPV _k,] Project net present value for decision,k, at production stage - [OPR _k,] Ore production rate for decision,k, at production stage, - [S ] State of the system in stage - [ _n] Immediate state objective vector at stage      

Detailed compositional analysis of gas seepage at the National Carbon Storage Test Site,Teapot Dome,Wyoming, USA

A baseline determination of CO₂ and CH₄ fluxes and soil gas concentrations of CO₂ and CH₄ was made over the Teapot Dome oil field in the Naval Petroleum Reserve No. 3 (NPR-3) in Wyoming, USA. This was done in anticipation of experimentation with CO₂ sequestration in the Pennsylvanian Tensleep Sandstone underlying the field at a depth of 1680 m.The baseline data were collected during the winter, 2004 in order to minimize near-surface biological activity in the soil profile. The baseline data were used to select anomalous locations that may be the result of seeping thermogenic gas, along with background locations. Five 10-m holes were drilled, 3 of which had anomalous gas microseepage, and 2 were characterized as “background.” These were equipped for nested gas sampling at depths of 10-, 5-, 3-, 2-, and 1-m depths. Methane concentrations as high as 170,000 ppmv (17%) were found, along with high concentrations of C₂H₆, C₃H₈, n-C₄H₁₀, and i-C₄H₁₀. Much smaller concentrations of C₂H₄ and C₃H₆ were observed indicating the beginning of hydrocarbon oxidation in the anomalous holes. The anomalous 10-m holes also had high concentrations of isotopically enriched CO₂, indicating the oxidation of hydrocarbons. Concentrations of the gases decreased upward, as expected, indicating oxidation and transport into the atmosphere. The ancient source of the gases was confirmed by ¹⁴C determinations on CO₂, with radiocarbon ages approaching 38 ka within 5 m of the surface.Modeling was used to analyze the distribution of hydrocarbons in the anomalous and background 10-m holes. Diffusion alone was not sufficient to account for the hydrocarbon concentration distributions, however the data could be fit with the addition of a consumptive reaction. First-order rate constants for methanotrophic oxidation were obtained by inverse modeling. High rates of oxidation were found, particularly near the surface in the anomalous 10-m holes, demonstrating the effectiveness of the process in the attenuation of CH₄ microseepage. The results also demonstrate the importance of CH₄ measurements in the planning of a monitoring and verification program for geological CO₂ sequestration in sites with significant remaining hydrocarbons (i.e. spent oil reservoirs).