Variation Of Anisotropy Research Articles

Size effect of anisotropy in spatial variability of rocks: evaluation through digital drilling

Evaluating the anisotropy of rock and its size effect in spatial variation is of great significance for improving engineering efficiency and stability. For this purpose, an anisotropy index is used to quantify the magnitude of anisotropy in rock. Digital drilling tests are carried out in three directions on six types of rock to investigate the anisotropy of drilling parameters. The rock is subdivided into multiple small units along the depth of drilling, and the effect of size on rock anisotropy based on drilling work was studied. The research findings indicate that the drilling work on six rock types exhibits anisotropy, and the anisotropy sequence for the total drilling work of each rock is as follows: red sandstone > granite > slate > gneiss > sandstone > argillaceous sandstone. As the length of rock units increases, the anisotropy index of drilling work initially exhibits a fluctuating trend, subsequently reaching a state of stability, thereby manifesting a size effect. Furthermore, the representative elementary volume (REV) for each type of rock exhibits distinct variations. The anisotropy indices for drilling work along the depth of the borehole exhibit an initial phase of rapid increase, followed by a convergence towards a value close to 1.0. The anisotropy of rocks demonstrates size dependence, and size effects also exhibit anisotropy. Anisotropy and its size effects are interconnected and inseparable. The reliability of the cited anisotropy index is checked by comparison with two other anisotropy indices. This comparison shows that our method can reliably determine rock anisotropy. In summary, the research outlined in this paper presents a highly efficient and straightforward approach to evaluate the effect of size on rock anisotropy.

Characterization of 2D Transition Metal Dichalcogenides Through Anisotropic Exciton Behaviors.

This study reports the first attempt to characterize the quality, defects, and strain of as-grown monolayer transition metal dichalcogenide (TMDC)-based 2D materials through exciton anisotropy. A standard ellipsometric parameter (Ψ) to observe anisotropic exciton behavior in monolayer 2D materials is used. According to the strong exciton effect from phonon-electron coupling processes, the change in the exciton in the Van Hove singularity is sensitive to lattice distortions such as defects and strain. In comparison with Raman spectroscopy, the variations in exciton anisotropy in Ψ are more sensitive for detecting slight changes in the quality and strain of monolayer TMDC films. Moreover, the optical power requirement for TMDC characterization through exciton anisotropy in Ψ is ≈10-5mWcm-2, which is significantly less than that of Raman spectroscopy (≈106mWcm-2). The standard deviation of the signals varies with strain (defects) in Raman spectra and exciton anisotropies in Ψ are 0.700 (0.795) and 0.033 (0.073), indicating that exciton anisotropy is more sensitive to slight changes in the quality of monolayer TMDC films.

Anisotropic Rayleigh wave tomography revealed lithospheric modification and tectonic deformation mechanisms in Hubei Province, central China

The collision of the North China and Yangtze blocks, along with multiple orogenic movements, has caused complex tectonic deformation of the lithosphere in Hubei Province. In order to reveal the stress distribution features and tectonic deformation mechanisms of the regional lithosphere, we inverted an azimuthal anisotropic structural model of the Hubei lithosphere from anisotropic Rayleigh wave tomography with data obtained from 48 broadband seismometers deployed in and around the province. Our model revealed strong lateral variations of azimuthal anisotropy in the crust and upper mantle, providing new seismological evidence for the lithospheric modification of the Yangtze block and the layered deformation of the lithosphere east of the North-South Gravity Lineament. We speculate that the primary dynamic factor causing lithospheric modification in the Yangtze block is related to the rifting events associated with the super-mantle plume, triggered by the deep subduction of the Pacific and Philippine plates. Meanwhile, the rifting event is also the main cause of the lithospheric structural layered deformation east of the North-South Gravity Lineament. The inverted anisotropic model, together with the results of previous geodetic and seismologic studies, revealed the causes and tectonic deformation mechanisms of anisotropy generation in the crust and upper mantle in Hubei Province. Crustal deformation in the Hubei region may be related to the eastward expansion of materials from the Tibetan Plateau and the ultra-high pressure metamorphic zone formed by the subduction and collision of the Yangtze and North China blocks, while upper mantle deformation is associated with subduction and collision of Yangtze and North China blocks, preserved fossil anisotropy from previous orogenic movements, and rifting events tied to the super-mantle plume induced by the deep subduction of the Pacific and Philippine plates. Moreover, we analyzed the regional crust-mantle coupling mechanism and concluded that the crust-mantle in the Dabie orogenic belt is coupled, whereas it is decoupled in other regions.

Anisotropic Velocity Structure Beneath Shikoku, Japan: Insights From Receiver Function and Shear Wave Splitting Analyses

AbstractA combination of receiver function (RF) analysis and shear wave splitting can reveal the anisotropic properties of the Earth's velocity structure. The RF profile exhibits harmonic patterns partially generated from the discontinuities of anisotropic media near the receiver. The anisotropic properties are determined using splitting parameters, which include the fast polarization direction (FPD) and split time. We utilized the seismograms recorded by stations on Shikoku Island, Japan. Also, we applied the Bayesian information criterion to control the spike count of each RF, which consists of a series of spikes generated by time‐domain iterative deconvolution. Anisotropic differences arose between northern and southern regions along the 30‐km iso‐depth line of the top surface of the Philippine Sea Plate. In the southern part of Shikoku Island, the FPDs are sub‐perpendicular to the plunge of the subducting slab, while in the northern part, they are sub‐parallel to the plunge of the slab. Our results indicate that anisotropic strengths are weaker in the tectonic‐tremor band in northwestern Shikoku and stronger in the northern part of central and eastern Shikoku around the no tectonic‐tremor area. These anisotropic variations may characterize Shikoku Island’s geological structure.

Influence of particle shape on creep and stress relaxation behaviors of granular materials based on DEM

The creep and stress relaxation behaviors stem from time-dependent changes in the microstructure of granular materials. As a non-negligible inherent granular material characteristic, particle shape plays a significant role on the formation and evolution of microstructure. However, the effects of particle shape on creep and stress relaxation behaviors of granular materials are still open questions. In this study, 3D DEM models based on the rate process theory and superellipsoids are incorporated to simulate the creep and stress relaxation of granular samples with different aspect ratios and blockiness. The results show that the aspect ratio and blockiness of particle have a great effect on creep and stress relaxation. However, the effects of aspect ratio and blockiness on creep and stress relaxation are coupled. Further analysis on contact forces shows the influences of aspect ratio and blockiness on creep mainly come from the contact force ratio. The influences of the aspect ratio and blockiness on stress relaxation mainly arise from the variation of the normal contact force anisotropy of the granular assemblies. The above results provide the tendency and mechanism on the effects of particle shape on creep and stress relaxation of granular assemblies.

Combined influence of rotated transverse anisotropy in mechanical parameters and hydraulic conductivity of soils on reliability evaluation of an unsaturated slope under rainfalls

Natural slopes often exhibit tilted stratification with rotated transverse anisotropy in multiple soil properties, including the mechanical (e.g., friction angle φ and cohesion c) and hydraulic properties (e.g., saturated hydraulic conductivity ks). This phenomenon indicates that to achieve an accurate assessment of slope reliability under rainfall infiltration, the anisotropic spatial variation of the shear strength parameters and ks should be incorporated in a combined manner. Thus, this paper discusses the combined influence of rotated transverse anisotropy in the shear strength parameters and ks on the reliability and failure mechanism of an unsaturated slope under rainfalls. It is found that for a slope with tilted stratification, the failure mechanism and reliability estimator are dominantly influenced by the rotated transverse anisotropy in the shear strength parameters, while the influence induced by that in ks is slight. In particular, only incorporating the rotated transverse anisotropy in ks may lead to an incorrect reliability estimator of a slope with tilted stratification. Herein, the reliability index β would be estimated to be dramatically higher, and β of a slope with horizontal bedding would be higher than that of an anti-dip slope, which is inconsistent with the engineering experiences. Nonetheless, the rotated transverse anisotropy in ks should not be ignored in slope reliability assessment, because ignoring the rotated transverse anisotropy in ks would lead to overestimation of the reliability index β, which is adverse to the safety design of a slope.

Impact dynamics of granular debris flows based on a small-scale physical model

The peak pressure of a granular debris flow at low Froude conditions can be calculated with knowledge of the stress anisotropy and the bulk density as well as the run-up height at impact. Based on a small-scale physical model, measurements of stress anisotropy and flow density values at impact are presented and applied to existing run-up prediction models, and further compared with back-calculated run-up coefficients from measured maximum impact pressures. For this purpose, we conducted 17 experiments with impact measurements and six experiments without impact measurements at Froude numbers, ranging from 0.84 to 2.41. Our results indicate that run-up heights are best reproduced by predictive models, either based on energy or mass and moment conservation, when anisotropic stress conditions, found in this study to range from 1.2 to 5.0, and bulk density variations due to impact, ranging in this study from 0.8 to 2.3, are considered. The influence of stress anisotropy and density variation on the run-up prediction differs, depending on the modelling approach. For the calculation of run-up heights based on the energy conservation concept, the influence of stress anisotropy becomes more significant with increasing Froude number, whereas for models based on mass and momentum conservation, bulk density variations have a greater influence on the estimation of the potential run-up.

Observation of Strong Anisotropic Interlayer Excitons.

Anisotropic interlayer excitons had been theoretically predicted to exist in two-dimensional (2D) anisotropy/isotropy van der Waals heterojunctions. However, experimental results consolidating the theoretical prediction and exploring the related anisotropic optoelectronic response have not been reported so far. Herein, strong photoluminescence (PL) of anisotropic interlayer excitons is observed in a symmetric anisotropy/isotropy/anisotropy heterojunction exemplified by 3L-ReS2/1L-MoS2/3L-ReS2 using monolayer (1L) MoS2 and trilayer (3L) ReS2 as components. Sharp interlayer exciton PL peaks centered at ∼1.64, ∼1.61, and ∼1.57 eV are only observed at low temperatures of ≤120 K and become more pronounced as the temperature decreases. These interlayer excitons exhibit strong anisotropic PL intensity variations with periodicities of 180° as functions of the incident laser polarization angles. The polarization ratios of these interlayer excitons are calculated to be 1.33-1.45. Our study gives new insight into the manipulation of excitons in 2D materials and paves a new way for a rational design of novel anisotropic optoelectronic devices.

Characterizing rock transverse anisotropic spatial variations using digital drilling

Transverse anisotropy plays an important role in the engineering behavior of rock masses. This study examines the transverse anisotropic spatial variations and evaluates them using the coefficient of variation (CV) and anisotropy index (AI) through digital drilling tests. Four types of rocks, shale (SH), mudstone (MU), sandstone (SA), and schist (SC), are studied in four directions, revealing significant transverse anisotropy at the cutting point. The results demonstrate that the effect of the depth per rotation on the difference is weaker compared to the scaled weight and torque. The ranking of transverse anisotropy in the tested rocks is: MU > SA > SH > SC. Transverse anisotropy changes along the drilling depth vary across rock types. With the increase of drilling depth, SH experiences a decrease, rebound, and another decrease. MU shows an initial increase followed by a decrease. For SA, the degree of transverse anisotropy decreases and is sustained at a lower extent. SC exhibits slight fluctuations with the exception of the abrupt change. The time when the drilling bit is in perfect contact with the rock and the cutting efficiency in different drilling directions are the main factors causing the transverse anisotropy. The intricate evolution of transverse anisotropy should be worth investigating on a wider scale.

2D or not 2D? Mapping the in-depth inclination of the collagen fibers of the corneoscleral shell

The collagen fibers of the corneoscleral shell play a central role in the eye mechanical behavior. Although it is well-known that these fibers form a complex three-dimensional interwoven structure, biomechanical and microstructural studies often assume that the fibers are aligned in-plane with the tissues. This is convenient as it removes the out-of-plane components and allows focusing on the 2D maps of in-plane fiber organization that are often quite complex. The simplification, however, risks missing potentially important aspects of the tissue architecture and mechanics. In the cornea, for instance, fibers with high in-depth inclination have been shown to be mechanically important. Outside the cornea, the in-depth fiber orientations have not been characterized, preventing a deeper understanding of their potential roles. Our goal was to characterize in-depth collagen fiber organization over the whole corneoscleral shell. Seven sheep whole-globe axial sections from eyes fixed at an IOP of 50 mmHg were imaged using polarized light microscopy to measure collagen fiber orientations and density. In-depth fiber orientation distributions and anisotropy (degree of fiber alignment) accounting for fiber density were quantified over the whole sclera and in 15 regions: central cornea, peripheral cornea, limbus, anterior equator, equator, posterior equator, posterior sclera and peripapillary sclera on both nasal and temporal sides. Orientation distributions were fitted using a combination of a uniform distribution and a sum of π-periodic von Mises distributions, each with three parameters: primary orientation μ, fiber concentration factor k, and weighting factor a. To study the features of fibers that are not in-plane, i.e., fiber inclination, we quantified the percentage of inclined fibers and the range of inclination angles (half width at half maximum of inclination angle distribution). Our measurements showed that the fibers were not uniformly in-plane but exhibited instead a wide range of in-depth orientations, with fibers significantly more aligned in-plane in the anterior parts of the globe. We found that fitting the orientation distributions required between one and three π-periodic von Mises distributions with different primary orientations and fiber concentration factors. Regions of the posterior globe, particularly on the temporal side, had a larger percentage of inclined fibers and a larger range of inclination angles than anterior and equatorial regions. Variations of orientation distributions and anisotropies may imply varying out-of-plane tissue mechanical properties around the eye globe. Out-of-plane fibers could indicate fiber interweaving, not necessarily long, inclined fibers. Effects of small-scale fiber undulations, or crimp, were minimized by using tissues from eyes at high IOPs. These fiber features also play a role in tissue stiffness and stability and are therefore also important experimental information.

Structure and anisotropic optical properties of γ-InSe under high pressure

Pressure is believed to be one effective method to modify the structure and properties of 2D materials. In the present work, the structural transition and anisotropic properties of γ-InSe were in situ investigated under pressure using Raman, photoluminescence and infrared spectra, as well as the density functional theory. Results reveal that γ-InSe would transform to one metallic phase of InSe-III above 11.4 GPa. Below this transition pressure, γ-InSe completely transforms to the high temperature high pressure phase of InSe-II after three pressure up-down cycles. This is the first report on InSe-II obtained at ambient temperature. Besides phase transitions, one direct-to-indirect band transition is observed around 4 GPa. Angle-resolved polarized Raman spectra show all its three phonon modes exhibit 90° periodic variations, yielding a 4-fold symmetry. Pressure would not change its 4-fold symmetry, but its polarized angles vary with pressure. Therefore, pressure has important effect on γ-InSe that induces its structure change and thus results in its optical anisotropy variation.

Fracture mechanical properties and identification of principal stress direction from the rock frequency domain

The characterization of rock instability precursors and the identification of principal stress direction are essential for the safety construction of underground engineering. This study explores the characterization of rock instability precursors from the frequency domain and identification of principal stress direction by the anisotropy of frequency variation. The results show that the dense distribution of peak frequency and frequency centroid in the high frequency domain, along with an increase in peak frequency bandwidth and a decrease in mean frequency centroid value, can be used as frequency domain criteria for rockburst prediction and early warning. Both peak frequency and frequency centroid are effective monitoring parameters for rock instability. The anisotropic frequency centroid variation can be used to identify the principal stress direction, and a process is proposed. This paper not only offers a valuable complement to existing methods for rock instability precursor and principal stress direction identification, but also provides a new analytical method for stability monitoring in rock engineering.

MODELLING THE EVOLUTION OF THE TWO-PLANETARY THREE-BODY SYSTEM OF VARIABLE MASSES

A classical non-stationary three-body problem with two bodies of variable mass moving around the third body on quasi-periodic orbits is considered. In addition to the Newtonian gravitational attraction, the bodies are acted on by the reactive forces arising due to anisotropic variation of the masses. We show that Newtonian’s formalism may be generalized to the case of variable masses and equations of motion are derived in terms of the osculating elements of aperiodic motion on quasiconic sections. As equations of motion are not integrable the perturbative method is applied with the perturbing forces expanded into power series in terms of eccentricities and inclinations which are assumed to be small. Averaging these equations over the mean longitudes of the bodies in the absence of a mean-motion resonances, we obtain the differential equations describing the evolution of orbital parameters over long period of time. We solve the evolution equations numerically and demonstrate that the mass change modify essentially the system evolution.

Stochastic modeling of spatially-dependent elastoplastic parameters in 316L stainless steel produced by direct energy deposition

The stochastic modeling and calibration of an anisotropic elasto-plastic model for additive manufacturing materials are addressed in this work. We specifically focus on 316L stainless steel, produced by directed energy deposition. Tensile specimens machined from two additive manufactured (AM) box-structures were used to characterize material anisotropy and random spatial variations in elasticity and plasticity material parameters. Tensile specimens were cut parallel (horizontal) and perpendicular (vertical) to the AM deposition plane and were indexed by location. These results show substantial variability in both regimes, with fluctuation levels that differ between specimens loaded in the parallel and perpendicular build directions. Stochastic representations for the stiffness and Hill’s criterion coefficients random fields are presented next. Information-theoretic models are derived within the class of translation random fields, with the aim of promoting identifiability with limited data. The approach allows for the constitutive models to be generated on arbitrary geometries, using the so-called stochastic partial differential approach (to sampling). These representations are then partially calibrated using the aforementioned experimental results, hence enabling subsequent propagation analyses. Sampling is finally exemplified on the considered structure.

The mechanical properties and electronic structures of V, Cr, Mn, Fe, Ni atoms doped MoCoB by first‐principles calculation

AbstractMoCoB‐based cermets have been regarded as the potential substitution of WC cermets with high hardness, high melting point and high oxidation resistance. Ternary borides‐based cermets are widely used in extreme environment, such as high‐pressure environment. Therefore, it is significant to explore the mechanical properties and electronic structures of transition elements X (X = V, Mn, Fe, Ni) atoms doped MoCoB under high pressure, which are performed by first‐principles calculations to provide guidance for industry applications. The analysis of cohesive energy and formation enthalpy indicates high pressure leads to unstable states with lower lattice constants and crystal volumes. The deviation of cohesive energy and formation enthalpy indicate Mo4Co3FeB4 and Mo4Co3NiB4 have similar stability. The shear modulus, Young's modulus and bulk modulus increase under high pressure, which consists with the increasing of covalence. The variation of ductility and anisotropy indicate similar upward trend, which is verified by Poisson's ratio, B/G ratio and anisotropy index AU. The analysis of overlap population indicates high pressure leads to the increasing of covalence of B‐Co covalent bonds and the decreasing of the covalence of B‐Mo covalent bonds. The analysis of electronic structures indicates the high pressure leads to higher hybridization and lower density of states of metallic bonds. The analysis of charge density difference consists with the variation of mechanical properties, implying shorter bond length and higher bonds strength under high pressure.

Spatial-temporal Trends Mapping and Geostatistical Modelling of Groundwater Level Depth Over Northern Parts of Indo-Gangetic Basin, India

Haryana-Punjab is a vast part of the Indo-Gangetic basin (India), recognised globally as a major hotspot of groundwater abstraction and agricultural economic reliance. A lack of information is present in this region regarding spatiotemporal changes in groundwater levels. Geostatistical anisotropic processes are reliable, especially when the monitored regions are extensive. The modelling study involves a twofold objective. First, it estimates and evaluates anisotropic spatial variations in groundwater level depth (GWD, Surface to water level) using geostatistics for all four seasons of Indian cropping patterns—pre-monsoon, monsoon, post-monsoon (rabi) and post-monsoon (Kharif), and parameters of point kriging cross-validation (PKCV) are optimum, acceptable, and support the unbiasedness hypothesis of kriging. Based on the PKCV, five essential parameters were computed to accept the anisotropy semi-variogram fitted model. These are (1) kriging mean error (KME), ideally close to zero so that there are no over or underestimates, (2) goodness of fit (R2), (3) the ratio of estimated variance (EV) to kriging variance (KV) lies between 0.95-1.05, (4) good eye visualisation fit and (5) significant t-test on the correlation coefficient. The second objective is spatiotemporal modelling, a pixel-based Mann-Kendall trend testing (at 95% Confidence Interval) on kriged raster surfaces of GWD (For all four seasons) at 1km grid resolution. The trend, significant or not, is determined by the Mann-Kendall test, while Sen's slope estimator determines the slope magnitude of the trend. Results revealed that the study area's east-central to the central-northern region comes under a high depletion zone for groundwater levels. GWD significantly increased by 120cm/year-80cm/year in this region, and the mean kriged GWD for the entire study area increased by 30cm/year-29cm/year over 25 years. Seasonal climatological mean maps of kriged surfaces of GWD and mean rainfall surfaces in two different time phases for all four seasons have been evaluated. It is observed from these maps that wherever the rainfall is increasing, GWD is decreasing. Results clarified that anisotropic semi-variogram modelling with kriging, pixel-based trend analysis, and regression studies is a valuable tool for identifying the critical region of groundwater levels, and the central region of the study area falls under the severe depletion condition of the groundwater level.

Temperature Dependence of Magnetization Dynamics in Co/IrMn and Co/FeMn Exchange Biased Structures

Thin film ferromagnet/antiferromagnet (F/AF) exchange biased structures that are widely used in GMR spin valves are considered nowadays as promising systems for antiferromagnetic spintronic and spin-orbitronic devices. Here, the temperature dependences of magnetization dynamics in Co/IrMn and Co/FeMn F/AF structures are investigated using ferromagnetic resonance (FMR) in comparison to a free Co layer. A strong additional decrease in the resonance field was observed in Co/IrMn with a temperature decrease attributed to the rotatable anisotropy increase, which almost vanished at room temperature. In contrast to Co/IrMn, the contribution of the rotatable anisotropy in Co/FeMn is much weaker, even though it exists at RT, it is negative, and slightly varies with the temperature and resonance field shift in Co/FeMn. This is mainly due to unidirectional exchange anisotropy. FMR linewidth for the free Co layer increases with decreasing temperature and is accompanied with a slow relaxation process, while the additional contribution to FMR line broadening in Co/IrMn and Co/FeMn structures is correlated with variation in the exchange anisotropy. The observed results are discussed based on structural and surface morphology and magnetization reversal characterization using X-ray diffraction, atomic force microscopy, and vibrating sample magnetometry data.

Rock-physics modeling of elastic properties of multiscale fractured rocks

Fractures, often existing across various scales, control the mechanical and fluid flow properties of upper crustal rocks. Inferring fracture properties at different scales from multiband geophysical measurements is essential for many fields of earth and energy sciences. Under the framework of multiscale homogenization, we develop a rock-physics model to characterize the elastic and anisotropic properties of multiscale fractured rocks following a certain statistical law. The isotropic differential effective medium theory is used to model the elasticity of randomly oriented microcracks, and the linear slip theory is used to model the elasticity of oriented or randomly oriented macroscale fractures. For a multiscale fractured rock covered by six orders of fracture length (10−4 m to 102 m), it is found that velocity exhibits a decreasing trend with the increment of scale. Nevertheless, the different statistical distribution of multiscale fractures significantly affects the velocity and anisotropy variation pattern with scale. The velocity for the fractal distribution decreases significantly at the seismic scale, whereas, for the log-Gaussian distribution, the dramatic change in velocity occurs more at the ultrasonic and logging scales, depending on the length of the dominant fractures. We apply our methodology to interpret a set of multiscale geophysical data of P-wave velocity in a fractured carbonate formation and estimate that the multiscale fracture is possibly distributed in a log-Gaussian manner. Our elastic and anisotropic modeling strategy has the potential to predict the distribution pattern of fractures, especially by reconciling the multifrequency geophysical measurements (e.g., ultrasonic, logging, and seismic data).

Continental Fragments in the South China Block: Constraints From Crustal Radial Anisotropy

AbstractThe lithospheric architecture of the South China Block (SCB) is crucial to understanding the formation and evolution of this distinctive and highly reworked continental lithosphere with over 3 billion years of tectonic history. However, due to a lack of high‐resolution geophysical datasets, a detailed picture of the SCB lithosphere is absent, and fundamental questions regarding its formation, assembly, and subsequent reworking processes are actively debated. Assuming that unique deformation patterns due to such tectonic processes can be mapped by seismic anisotropy, we present a new crustal radially anisotropic shear‐wave velocity model along a 1500‐km seismic transect that spans the major tectonic domains of the SCB to characterize the past deformation processes. The new seismic models show significant lateral variations in seismic anisotropy and velocity, suggesting that the SCB consists of several separated (micro)continental blocks or terranes that likely have different origins and have survived the prolonged deformation history since the early formation of these continental fragments. Combining available geophysical datasets, we link individual crustal domains of distinct anisotropy to constrain the multiphase deformation processes of the SCB, including the early formation of the Proto‐Yangtze and Cathaysia Blocks, the assembly of the SCB, and the subsequent reactivation of the interior and extensive deformation that have formed the Basin‐and‐Range style tectonics in the Cathaysia Block. We suggest that relict continental fragments have played critical roles in the formation and reactivation of the SCB lithosphere.

Measurement of electron energetics in the equatorial and polar planes of a compact dipole plasma driven at steady state

The electron energy distribution function (EEDF) is investigated in a plasma driven at steady state and confined by a single permanent dipole magnet, employing electron cyclotron resonance heating using microwaves of 2.45 GHz. Directional retarding field energy analyzers are used to explore the EEDF in the equatorial and polar planes of the dipole magnetic field. The plasma confined in the magnetic field is found to be Maxwellian in most of the available space. Electrons have higher values of average energy () in the direction parallel to the magnetic field for both the equatorial and polar planes. The energetic electron rich regions are found at specific locations (r = 9 cm in the equatorial plane, and r = 5 cm and near the boundary region around r = 17 cm in the polar plane). The process rates such as electron neutral collisions and ionization show anisotropic variation in the polar plane of the dipole plasma.