Current Density Flow Research Articles

An intelligent CFRP bolt with embedded carbon nanotube eddy current sensors for damage self‐diagnosis of bolted composite joints

AbstractRecognizing the critical demand for composite bolts and the damage‐mode complexity of composite bolt joints, this study introduces the concept of an intelligent carbon fiber reinforced polymer (CFRP) bolt, which achieves self‐monitoring of damage in small and complex CFRP bolted joints. The proposed eddy current sensor (ECS) is mainly composed of a coil made of carbon nanotube film and encapsulated with epoxy resin film. This achieves homogeneous embedding of the sensor by using the same material for both sensor and bolt. The CFRP bolt is fabricated by molding process, with the proposed ECS embedded in bolt shank. The numerical simulation results indicate that hole‐edge damages impact the distribution of induced current density and eddy current flow in CFRP plates. Additionally, the impedance amplitude of the ECS effectively monitors bearing damage propagation. Shear tests confirm that the integration method of the proposed ECS within the CFRP bolt introduces negligible intrusion to the host bolt's integrity. Experimental results demonstrate that the intelligent CFRP bolt can effectively monitor the damage propagation at the hole edge, with an accuracy for bearing damage exceeding 0.5 mm. At a working frequency of 10 MHz, the sensor's sensitivity in detecting a 0.5 mm bearing damage reaches 4.20%.Highlights An intelligent CFRP bolt was fabricated using the molding method. The embedding of the ECS did not cause adverse effects on the bolt. The proposed EC sensor is composed of carbon nanotube and epoxy resin adhesive films. The eddy current distribution at the hole edge of the CFRP bolted joints is analyzed. The ability of intelligent bolts to monitor hole edge damage is verified by experiments.

Numerical solution of Lock-exchange flow in a curved channel with an obstacle

Gravity currents modify their flow characteristics in the presence of an obstacle. Also, the flow path to the dam reservoirs is not always direct. Since no studies have addressed the feedback between the hydrodynamics of a gravity current in a curved channel and the location effects of the obstacle, in this research, a Lock-exchange density current flows in a 120[Formula: see text] bending channel. The numerical simulation has been performed using OpenFOAM software. The models include no-obstacle curved channel and a curved channel with an obstacle in different positions concerning the increased radius of the curved channel. Results indicated that the obstacle directed the concentration towards the banks, with its maximum value tending from the outer to the inner bank, especially in the tail. The tail longitudinal velocity maximized near the channel bed in areas far from the obstacle, and in the outer bank in areas near it. The secondary flow reduces its lowest and most different pattern observed around the obstacle. In displacing the latter, if the front has at a certain distance, the secondary flow does not change much, but if it has at the channel end, the post-obstacle secondary flow would increase as the obstacle neared the Lock.

Interaction of near-cathode plasma layers with thermionic electrodes under high pressure arc plasma

Theoretical calculations and simulation data were presented to study the effect of the Xe-Dy mixture on properties of arc plasma. The effect of voltage, concentration and temperature on current flow density, power flux density and cathode temperature were studied. Different concentrations of Dysprosium (0.005, 0.01, 0.05, 0.1, and 0.5 mol) were used. The program (NCBL) was used in this work. Results showed a clear effect of concentration on plasma parameters, especially at the highest concentration, in addition to the effect of voltage. We notice that the current density increases from ≥3500k), while (3500 – 5000k) increases for all concentrations due to collisions as well as density of flowing energy For all the concentrations mentioned, we noticed that there is a clear effect of the temperature (≥ 3500k) on current density where increases and from (3500- 5000). we noticed an increase in the current density as well as the voltage especially at (25v) where the current and the energy overflow density increase due to elastic and inelastic collisions because acceleration of electrons with an increase in voltage.

Microbial Electrochemically Assisted Treatment Wetlands: Current Flow Density as a Performance Indicator in Real-Scale Systems in Mediterranean and Northern European Locations.

A METland is an innovative treatment wetland (TW) that relies on the stimulation of electroactive bacteria (EAB) to enhance the degradation of pollutants. The METland is designed in a short-circuit mode (in the absence of an external circuit) using an electroconductive bed capable of accepting electrons from the microbial metabolism of pollutants. Although METlands are proven to be highly efficient in removing organic pollutants, the study of in situ EAB activity in full-scale systems is a challenge due to the absence of a two-electrode configuration. For the first time, four independent full-scale METland systems were tested for the removal of organic pollutants and nutrients, establishing a correlation with the electroactive response generated by the presence of EAB. The removal efficiency of the systems was enhanced by plants and mixed oxic–anoxic conditions, with an average removal of 56 g of chemical oxygen demand (COD) mbed material–3 day–1 and 2 g of total nitrogen (TN) mbed material–3 day–1 for Ørby 2 (partially saturated system). The estimated electron current density (J) provides evidence of the presence of EAB and its relationship with the removal of organic matter. The tested METland systems reached the max. values of 188.14 mA m–2 (planted system; IMDEA 1), 223.84 mA m–2 (non-planted system; IMDEA 2), 125.96 mA m–2 (full saturated system; Ørby 1), and 123.01 mA m–2 (partially saturated system; Ørby 2). These electron flow values were remarkable for systems that were not designed for energy harvesting and unequivocally show how electrons circulate even in the absence of a two-electrode system. The relation between organic load rate (OLR) at the inlet and coulombic efficiency (CE; %) showed a decreasing trend, with values ranging from 8.8 to 53% (OLR from 2.0 to 16.4 g COD m–2 day–1) for IMDEA systems and from 0.8 to 2.5% (OLR from 41.9 to 45.6 g COD m–2 day–1) for Ørby systems. This pattern denotes that the treatment of complex mixtures such as real wastewater with high and variable OLR should not necessarily result in high CE values. METland technology was validated as an innovative and efficient solution for treating wastewater for decentralized locations.

Generalized hydrodynamics study of the one-dimensional Hubbard model: Stationary clogging and proportionality of spin, charge, and energy currents

In our previous work [Nozawa and Tsunetsugu, Phys. Rev. B 101, 035121 (2020)], we studied the quench dynamics in the one-dimensional Hubbard model based on the generalized hydrodynamics theory for a partitioning protocol and showed the presence of a clogging phenomenon. Clogging is a phenomenon where vanishing charge current coexists with nonzero energy current, and we found it for the initial conditions that the left half of the system is prepared to be half filling at high temperatures with the right half being empty. Clogging occurs at all the sites in the left half and lasts for a time proportional to its distance from the connection point. In this paper, we use various different initial conditions and discuss two issues. The first issue is the possibility of clogging in a stationary state. When the electron density in the right half is initially set nonzero, we found that the left half-filled part expands for various sets of parameters in the initial condition. This means that the clogging phenomenon occurs at all the sites in the long-time stationary state, and we also discuss its origin. In addition, stationary clogging is accompanied by a back current, namely, particle density current flows towards the high-density region. We also found that spin clogging occurs for some initial conditions, i.e., the vanishing spin current coexists with nonzero energy current. The second issue is the proportionality of spin and charge currents. We found two spatiotemporal regions where the current ratio is fixed to a nonzero constant. We numerically studied how the current ratio depends on various initial conditions. We also studied the ratio of charge and energy currents.

Calibration of the AC Potential Dropping System (ACPD) for Determination of Crack Growth in API 5L X65 Steel under Cathodic Protection Effect

In this work the calibration of an Alternative Current Potential Drop (ACPD) system was performed to monitore laboratory mechanical tests on marine environment under cathodic protection. The calibration was done on CT type specimens of API 5L X65 steel dimensioned according to ASTM E1820 standard., The crack propagation during a tensile test with displacement control in an ACPD equipment was monitored through the performs points collection by two channels: one that monitors the crack growth and another that monitors a region free of crack. Using a profile projector and graphical data processing and analysis software, the area of ​​the fracture surface of the specimen was meansured, which allowed to correlate a crack size with a corresponding value of potential drop and the calibration curve. In order to verify verify the efficacy and precision of the technique, step loading tests were performed on API 5L X65 steel test specimens, submerged in synthetic sea water under the overprotection potential of-1300mVAg/AgCl. The results of the calibration showed few dispersed errors, and the main factors of this dispersion may be related to the geometry of the specimen and with variations in current flow density, which is influenced by corners and edges and by the presence of pick-up inductive. The calibration and its effectiveness can be verified through the results of the tests in marine environment, presenting crack lengths close to the actual values, confirming the effectiveness of the ACPD technique.

Decoding pyroclastic density current flow direction and shear conditions in the flow boundary zone via particle-fabric analysis

One of the greatest challenges in volcanology is extracting information from volcanic deposits that inform the conditions at the time of emplacement. Here we explore particle-shape fabric within samples from the column-collapse pyroclastic density current (PDC) deposits generated by the 18 May 1980 eruption of Mt. Saint Helens (MSH). Particle shape-fabric is the mutual alignment of particles within a sample, which is dependent on shearing conditions at the time of deposition. Here, particle shape-fabric is used to address the following hypotheses: (1) particle shape-fabric will align with bulk flow direction estimates made by previous studies, while resolving fine scale flow direction variations; (2) samples extracted from PDC deposits immediately above a basal contact will show higher extents of fabric development (i.e. clast alignment) relative to samples extracted well above the contact; and (3) samples extracted from cross-stratified deposits will have higher extents of fabric development relative to samples extracted from the massive facies. We find that fabric orientations approximate previous flow direction interpretations of general flow, from south to north, and channelization due to paleo-topography. Furthermore, shape-fabric records flow interaction with the substrate, created by debris avalanche deposits, leading to fine scale variations in flow paths. These variations are recorded in samples extracted near the substrate-deposit contact. Moreover, these samples do not show a higher measure of clast alignment relative to samples taken well above flow contacts but do exhibit bimodal clast alignment. This suggests some degree of traction transport and thus higher shearing conditions relative to when the currents deposited massive lapilli tuffs. Samples extracted from the cross-stratified deposits do not show higher extents of fabric development relative to the massive deposits, supporting previous interpretations that these deposits formed from a rapidly sedimenting, concentrated flow boundary zone that was thin enough to be frequently interrupted or influenced by the overriding turbulent portion of the flow. Finally, observations of fine scale variability in measured fabric within a single outcrop indicates unsteady flow conditions and step-wise aggradation during deposition. This work demonstrates that particle shape-fabric analyses can aid in decoding PDC flow conditions. Future complementary experimental work may allow for the extraction of quantitative information regarding the magnitudes of shear and subsequent particle alignments within the flow boundary zone, providing further insight into PDC dynamics.

Effect of grid and optimization on improving the electrical performance of compound parabolic concentrator photovoltaic cells

The compound parabolic concentrator photovoltaic (CPC-PV) cell module is composed of two symmetrical mirrors and a crystalline silicon solar cell. In this study, two new CPC-PV cells based on known CPC-PV cell are established by changing the location and number of bus-bar in crystalline silicon solar cell. The effect of different location and number of bus-bar on the electrical performance of CPC-PV cells was investigated. The numerical simulation of three CPC-PV cells is performed using a two-dimensional finite element model. The electrical performance of three CPC-PV cells are compared, and surface voltage distribution, current density and internal current flow of the crystalline silicon solar cell for each CPC-PV cell are analyzed. The results show that compared with the known CPC-PV cell with bus-bar placed on the right side of the crystalline silicon solar cell, the electrical efficiency of the CPC-PV cell when the bus-bar is placed in middle region of the crystalline silicon solar cell is relatively improved by 14.76%. Finally, it is concluded that the bus-bar optimization based on the non-uniform illumination intensity distribution formed by the concentrator will help to improve the electrical performance of the CPC-PV cell.

Inferring pyroclastic density current flow conditions using syn-depositional sedimentary structures

The processes occurring in the basal region of concentrated pyroclastic density currents (PDCs) influence the mobility, runout distance, and damage potential of a current, but directly observing these processes is extremely difficult. Instead, we must investigate the deposits to glean information regarding the conditions of sediment transport and deposition. The PDC deposits of the May 18, 1980 eruption of Mount St. Helens (WA, USA) contain sedimentary structures consisting of bed material reworked into undulose structures and recumbent flame structures. The structures vary over two orders of magnitude in size with lengths ranging from 8 cm to 18 m and heights ranging from 4 cm to 1.8 m. Despite the large range in sizes, the structures remain self-similar in form, suggesting a common mechanism for formation. The structures are interpreted as the record of granular shear instabilities, similar to Kelvin-Helmholtz instabilities, formed at the interface between a shearing, high-concentration flow and the substrate in the moments just prior to deposition. The morphology of the structures suggests that the basal region of PDCs must be both highly concentrated and also highly mobile in the moments before final deposition, likely a result of elevated pore fluid pressures. We use a modified instability growth criterion to estimate PDC flow velocities at the time of formation; for the Mount St. Helens PDCs, the velocity estimates range from 0.2 to 7.5 m s−1 with larger structures requiring higher flow velocities. Combining the velocity estimates with the dimensions of the structures suggests deposition rates of 4 to 32 cm s−1. Such high deposition rates indicate that the deposits likely accumulated in a stepwise manner, rather than either progressively or en masse. The structures suggest that sections of the deposit accumulated during punctuated periods of high deposition lasting at most a few seconds followed by periods of bypassing (i.e., non-deposition) or erosion lasting minutes to tens of minutes. Our findings motivate continued experimental and numerical work to understand how the formation of recumbent flame (and similar) structures affects subsequent flow behavior in terms of runout distance and hazard potential.

Estimation of Reservoir Sediment Flux through Bottom Outlet with Combination of Numerical and Empirical Methods

Sediment deposition issues for reservoirs are important in Taiwan because the severe deposition could excessively decrease the reservoir lifecycle. Extreme storm events usually can carry a massive amount of sediment into reservoirs, and deposition will happen unless the incoming material can pass through sluice gates. When it comes with high concentration, the density current flow is prone to be generated, and the bottom outlets are the most effective sluice gate to release the sediment. In order to improve the sediment release efficiency, an accurate estimation of arriving concentration and time of the density current can be useful for the reservoir management. This study develops a two-stage approach which combines a numerical model (SRH2D) and the modified Rouse equation to predict the sediment flux of the reservoir. The numerical model was verified and applied to establish the relation between inflow and dam face concentration. The modified Rouse equation then adopted this relation to estimate the proper exponential parameter. As a result, the sediment flux amount at each bottom outlet can be accurately predicted by this equation. With this means, an early warning system can be established for reservoir operation, which can improve release efficiency during typhoons.

Large eddy simulation of density current on sloping beds

We carry out high-resolution large-eddy simulation (LES) of stratified flows developing as dense underflows over two different bed slopes of 5° and 15° in an laboratory-scale tank. Simulations for the corresponding unstratified flows are also carried out to help elucidate the effects of stratification on the dynamics of the flow and overall evolution of the effluent front. The simulated density current flows have also been investigated experimentally by continuously releasing down a sloping plane a fluid that is slightly denser than the ambient fluid. The Navier Stokes equations with the Boussinesq approximation, to account for the stratification due to density difference, are solved numerically using a second-order accurate finite-difference method (Khosronejad and Sotiropoulos, 2014). The simulated structure of the density currents at quasi-equilibrium are shown to be in reasonable agreement with the experimental observations. The variation of the half-width of the density current plume with downstream length is shown to exhibit different power law regimes on a log scale. Spectral analysis reveal existence of large scale structures in the flow. Comparative analysis of the dynamics of the coherent structures in the stratified and non-stratified flows reveal that stratification has a profound effect on the large-scale features of the flow.

An experimental study on plunging depth of density currents

Mass density of the current flows is the one of the important problem in the hydraulics of the dam reservoir. Plunge point occurs when the mass density current penetrates in the stagnant fluid. Recognition the place of this point is very important because of clearing the boundary of the density current flow and ambient fluid. In this study the influences of bed slope and hydraulic parameters on plunging depth were experimentally investigated. The results show that the slope has a minor effect on the plunging depth. The height of plunging depth is increased by increasing the density of the current flow. Also increasing the densimetric Froude number caused of decreasing the plunging depth. Finally an equation was proposed to estimate the plunging depth using as function of flow characteristics.

Noninvasive Methods for Hydraulic Characterization of Density Currents with Application to Submarine Fan Experiments

AbstractLaboratory experiments are a convenient way to study morphodynamic processes associated with subaqueous fans. However, the flows driving such systems can be difficult to hydraulically characterize due to the shallowness of the flows, the spatial and temporal dynamics of the autogenic channels, and the mixing at the interface of the ambient fluid and density current. The objective of this study is to develop a set of methods to quantify hydraulic variables in laterally unconstrained and morphologically active density currents. Herein, a methodology is presented capable of characterizing a density current flow field with direct application to submarine fan experiments. This is done with a combination of: (1) particle tracking velocimetry (PTV) analysis of tracers within the density current, (2) flow width measurements from overhead images, and (3) solution of the mass and volume conservation equations in one-dimension to obtain layer-averaged velocity, depth, and fractional excess density.

The Influence Factors of Perennial Outbreak Algal Bloom in Xiangxi Bay Upstream

To study the influence factors of perennial outbreak blooms in Xiangxi Bay (XXB) upstream, field data of Chlorophyll a (Chl.a) and TN and TP, and sediment concentration,2010. The result show: the Chl.a concentration is higher in XXB upstream, January until the end of September is particularly serious, XX10 Chl.a concentration was 227.84 mg/m3 in Feb.7, XX07 Chl.a concentration was 215.98 mg/m3 in June.2; the high levels of nutrient from upstream flow is the main cause of perennial outbreak blooms in XXB upstream, and at the same time, the slope density current and adverse slope density flow also have a great influence to it.

Development of Thin-Film Manufacturing Technologies for Solid Oxide Fuel Cells and Gas Separation Membranes

The development of solid oxide fuel cells (SOFCs) and gas separation membranes for fossil (fuel?) power plants has previously suffered from cost issues like the manufacturing of the core components including i) the ceramic fuel cell and ii) the ceramic membrane, and from insufficient power density (current density or flow rate) on the stack, module or system level. Forschungszentrum Jülich has been working on SOFC development for 20 years, and on membrane development for 6 years. Both energy-related applications are based on similar materials systems, similar micro-structural features (porous-dense, coarse-fine), comparable application parameters (e.g. high temperature) and are manufactured with similar technologies. In the past the focus laid mostly on basic materials research and proving the functionality of the membranes or fuel cells. Meanwhile, one key topic has been the application of low-cost thin-film high-throughput manufacturing technologies. This includes the fabrication of the supports (mostly tape-casting), the coating with functional layers by ceramics technologies (screen printing, roll coating) and the reduction of sintering steps and temperatures. Additionally special thin-film technologies like sol-gel technique and electron beam evaporation / sputtering have also been applied for functional layers, depending on the functional necessities. The presentation gives an overview regarding the state-of-the-art in SOFC and gas separation membrane development at Forschungszentrum Jülich with an emphasis on the manufacturing technologies, resulting in optimized layer micro-structures and thickness. Additionally it summarizes the electrochemical and permeation data obtained so far.

A Neoproterozoic continental rift succession: The volcano-sedimentary Koivib Mountains deposits of Namibia

Neoproterozoic volcanic and sedimentary rocks compose the 750m thick Koivib Mountains succession, which forms part of the Rosh Pinah Formation of southwest Namibia. Detailed sedimentary facies analysis and physical volcanology enabled determination of four lithofacies and component twelve facies that record subaqueous deposition in a tectonically controlled shallow sea. The mafic volcanic lithofacies is composed of mafic: (1) flow, (2) volcaniclastic, and (3) intrusive facies characteristic of seamount building by effusive volcanic processes. The felsic volcanic lithofacies containing felsic: (4) flow and (5) volcaniclastic facies displays features characteristic of proximal to distal and marginal regions of subaqueous dome–flow complexes. The siliciclastic lithofacies composed of (6) shale, (7) thin- to medium-bedded sandstone, (8) thick-bedded sandstone, and (9) sedimentary breccia facies is consistent with a submarine fan environment in which subaqueous density current and turbidity flow processes were predominant. The silicilastic–carbonate lithofacies, which contains (10) massive bedded carbonate, (11) laminated to cross-bedded calcarenite, and (12) graded bedded calcarenite, formed mainly through erosion of primary carbonate and transport of material from a platform to a slope setting. The overall stratigraphy, combined with geochemical results indicating bimodal volcanism in a within-plate tectonic setting, signifies that the Koivib Mountains succession developed as part of a continental rift sequence associated with Neoproterozoic break-up of the Rodinia supercontinent. The structural geology of the Koivib Mountains revealed two generations of folds, including (i) NW trending tight, isoclinal folds (F1) and (ii) NNW trending open folds (F2). The second deformation event refolded F1 folds, producing periclinal structures. The deformation features are consistent with SE transpression associated with the continental collision that occurred during closure of the Adamastor Ocean and formation of Gondwana.

The Relationship between Flux Coefficient and Entrainment Ratio in Density Currents

Abstract The authors explore the theoretical and empirical relationship between the nonlocal quantities of the entrainment ratio E, the appropriately depth- and time-averaged flux coefficient Γ, and the bulk Froude number Fro in density currents. The main theoretical result is that E = 0.125 Γ Fro2(CU3/CL)/cosθ, where θ is the angle of the slope over which the density current flows, CL is the ratio the turbulent length scale to the depth of the density current, and CU is the ratio of the turbulent velocity scale to the mean velocity of the density current. In the case of high bulk Froude numbers Γ ∼ Fro−2 and (CU3/CL) = Cε ∼ 1, so E ∼ 0.1, consistent with observations of a constant entrainment ratio in unstratified jets and weakly stratified plumes. For bulk Froude numbers close to one, Γ is constant and has a value in the range of 0.1–0.3, which means that E ∼ Fro2, again in agreement with observations and previous experiments. For bulk Froude numbers less than one, Γ decreases rapidly with bulk Froude number, explaining the sudden decrease in entrainment ratios that has been observed in all field and experimental observations.

Charring of woods by volcanic processes: An example from the Taupo ignimbrite, New Zealand

One of the most violent and explosive eruptions in historic times was that of the Taupo volcano in New Zealand 1800 years ago. This culminated in emplacement of the Taupo ignimbrite, laid down by a single vent-generated pyroclastic density current that entombed and preserved abundant plant material. The ignimbrite consists of two layers, generated by processes within the concentrated part of the density current (flow, sensu stricto) and where the current interacted with the atmosphere and the pre-eruptive vegetative cover. Eighty-four wood samples were collected from eight localities representing both layers, at varying distances from the vent, including the previously described Pureora Fossil Forest. Samples were studied by light, scanning electron and reflectance microscopy in order to determine their systematic affinity (angiosperm or conifer), degree of charring and reflectance values. Most samples (59) were conifer, probably derived from podocarps that are known to have been common in the pre-eruptive vegetation. Samples ranged from uncharred, through incompletely charred to fully charred woods. The variation in degrees of charring and reflectance values implies that the entrained charcoal did not equilibrate with the flow temperature. Minimum charring temperatures, interpreted from the mean of the three highest maximum reflectance values, showed no major differences between ignimbrite layers and were generally low, ranging from 269 to 398 °C. Both ignimbrite layers also show a trend of increasing deposit temperature away from the vent, consistent with estimates from palaeomagnetic techniques.

Observations and modeling of a pulsating density current

We investigate density current formation and flow in the northern Gulf of Eilat, Red Sea, using in situ observations and a high resolution, nonhydrostatic general circulation model. These density currents occur in relatively warm water ∼20°C and are probably the warmest in the world ocean. We demonstrate the intrinsic nonlinearity of density currents by comparing two high‐resolution simulations forced by different heat flux. This nonlinearity, which is poorly represented in global models, is shown here to affect the properties of simulated density currents. Such a bias in simulating density currents in global models may lead to significant biases on the larger scale global ocean circulation and water mass distribution.

Improvement of spatial homogeneity in IBAD based YBCO coated conductors

Prior to the development of fabrication technique for the chemical vapor deposited (CVD) YBa 2Cu 3O 7-δ coated conductor on a IBAD-Gd 2Zr 2O 7, investigations on the improvement of spatial homogeneity have been done. By using spatially resolved measurements and combined multiple microanalysis techniques with length scale of several μm, physical and transport properties of the CVD samples have been investigated before and after fabrication modification. Structural inhomogeneity was visualized using thermoelectric voltage imaging (TVI) technique using a laser scanning microscope. Laser scanning microscopy at superconducting temperature is used to visualize flux flow dissipation; furthermore, mappings of 2D local current flow density distribution have been done using a scanning SQUID microscopy. It has been shown that the superconducting layer consisted of YBCO matrix with localized defects originating from the buffer layer. This led to current non-uniformity and caused high flux flow dissipation within the vicinity of the defects. Process conditions have been modified effectively based on those insights. After fabrication modification, our measurement analyses shows that the texturing of the YBCO layer improved significantly and the appearance of spatially distributed obstacles that are responsible for non-uniform current distribution and localized dissipation are reduced. Our complementing, quick yet non-invasive technique not only can quantify the improvement of YBCO homogeneity but also shed light on the basic understanding of the current limiting mechanism in the IBAD based coated conductors.