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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Creep Properties of Shale and Predicted Impact on Proppant Embedment for the Caney Shale, Oklahoma

The Caney shale is an emerging hydrocarbon play located in southwest Oklahoma, USA. Within the Caney shale exist facies which were initially dubbed “reservoir” and “ductile” based on evaluation of well logging data. While past work has shown the distinction of “brittle” and “ductile” is not mechanically justifiable according to formal definitions, here the current work shows some important differences between nominally ductile and reservoir zones. First, the “ductile” zones are more clay rich and have textural differences which can be expected to lead to differences in mechanical properties. One important impact of these differences is observed in triaxial creep experiments showing the “ductile” zones are more prone to creep deformation. Numerical simulations predict the “reservoir” zones will experience very little proppant embedment due to creep deformation of hydraulic fractures around proppant particles. On the other hand, “ductile” zones can be expected to undergo creep-driven proppant embedment leading to loss of fracture aperture ranging up to 100% loss, depending upon the spatial density of the proppant distribution. Hence, this research shows the identification of nominally “ductile” zones from well logs, while a misnomer, can be useful in finding clay-rich, creep-prone zones which will be the most prone to proppant embedment and hence vulnerable to greater production decline over time.

58 GEOSCIENCES↗
DOE OSTI2025

Coupled Thermo-Hydrological-Mechanical-Chemical Behavior of Anisotropic Granite for Geologic Disposal of High-Level Radioactive Waste: A Core-Scale Laboratory Investigation

The coupled thermo-hydrological-mechanical-chemical (THMC) behavior of rock within an Excavation Damaged Zone (EDZ) is critical for the safety and long-term performance of a geological repository for high-level radioactive wastes. While many laboratory experiments have been conducted to investigate EDZ rocks, the flow and deformation characteristics resulting from anisotropic rock textures and microcrack distribution under triaxial loading and elevated temperatures remain poorly understood. Particularly, cracks at various scales serve as fast paths for fluid flow and solute transport and present as focal points of mechanical weakness, which complicate the coupled THMC processes in anisotropic EDZ rocks and challenge modeling predictions. Here, in this study, a series of core-scale experiments was conducted on three granite samples under repository-relevant conditions. These rock samples were obtained from the Grimsel Underground Research Laboratory (URL), featured by anisotropic minerals (represented by bedding layers) and microcrack distributions and coarse cm-scale grain sizes. During the experiments, samples were subjected to an elevated temperature at 90 °C and different triaxial loading conditions either by radial (normal to bedding layers) or axial (parallel to bedding layers) compaction. Water was injected into the samples, and the rock permeability evolutions and effluent water chemistry were monitored closely. For intact samples, thermal expansion of minerals at 90 °C resulted in a large, 75% irreversible permeability reduction and rock strengthening under radial compaction, while thermal impact was limited to a 15% permeability reduction under axial compaction. In contrast, for a sample containing open cracks, the growth of fractures during the experiment resulted in an abrupt permeability increase and fast failure at 90 °C. The effluent water chemistry indicates much more considerable mineral dissolution from large shear sliding than that in rocks dominated by mechanical compaction. These results helped better understand the coupled THMC processes in anisotropic rocks containing cracks, evaluate the behaviors of EDZ rocks, and predict the long-term evolution of EDZ for the performance of the repositories.

Coupled THMC processes↗
DOE OSTI2020

Fine Root and Soil Organic Carbon Depth Distributions are Inversely Related Across Fertility and Rainfall Gradients in Lowland Tropical Forests

Humid tropical forests contain some of the largest soil organic carbon (SOC) stocks on Earth. Much of this SOC is in subsoil, yet variation in the distribution of SOC through the soil profile remains poorly characterized across tropical forests. We used a correlative approach to quantify relationships among depth distributions of SOC, fine root biomass, nutrients and texture to 1 m depths across 43 lowland tropical forests in Panama. The sites span rainfall and soil fertility gradients, and these are largely uncorrelated for these sites. We used fitted b parameters to characterize depth distributions, where b is a numerical index based on an asymptotic relationship, such that larger b values indicate greater concentrations of root biomass or SOC at depth in the profile. Root b values ranged from 0.82 to 0.95 and were best predicted by soil pH and extractable potassium (K) stocks. For example, the three most acidic (pH < 4) and Kpoor (< 20 g K m -2 ) soils contained 76 ± 5% of fine root biomass from 0 to 10 cm depth, while the three least acidic (pH > 6.0) and most K-rich (> 50 g K m -2 ) soils contained only 41 ± 9% of fine root biomass at this depth. Root b and SOC b values were inversely related, such that a large fine root biomass in surface soils corresponded to large SOC stocks in subsoils (50–100 cm). SOC b values were best predicted by soil pH and base cation stocks, with the three most base-poor soils containing 34 ± 8% of SOC from 50 to 100 cm depth, and the three most base-rich soils containing just 9 ± 2% of SOC at this depth. Nutrient depth distributions were not related to Root b or SOC b values. Here, these data show that large surface root biomass stocks are associated with large subsoil C stocks in strongly weathered tropical soils. Further studies are required to evaluate why this occurs, and whether changes in surface root biomass, as may occur with global change, could in turn influence SOC storage in tropical forest subsoils.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

Simulating seawater intrusion in a complex coastal karst aquifer using an improved variable-density flow and solute transport–conduit flow process model

VDFST-CFP (variable-density flow and solute transport–conduit flow process) is a density-dependent discrete-continuum numerical model for simulating seawater intrusion in a dual-permeability coastal karst aquifer. A previous study (Xu and Hu 2017) simulates variable-density flow only in a single conduit, and studies the parameter sensitivities only in the horizontal case (2D domain as horizontal section) by the VDFST-CFP model. This paper focuses on the density-dependent vertical case (2D domain as vertical section) with two major improvements: 1) when implementing double-conduit networks in the domain, simulated intruded plumes in the porous medium are extended in the double-conduit scenario, compared to the single-conduit system; 2) by quantifying micro-textures on the conduit wall by the Goudar-Sonnad equation and considering macro-structures as local head loss. Sensitivity analysis shows that medium hydraulic conductivity, conduit diameter and effective porosity are important parameters for simulating seawater intrusion in the discrete-continuum system. On the other hand, rougher micro-structures and additional macro-structure components on the conduit wall would reduce the distance of seawater intrusion to the conduit system, but, rarely affect salinity distribution in the matrix. Compared to the equivalent mean roughness height, the new method (with more detailed description of structure) simulates seawater intrusion slightly landward in the conduit system. Here, the macro-structure measured by local head loss is more reasonable but needs further study on conduit flow. Xu and Hu (2017) Development of a discrete-continuum VDFST-CFP numerical model for simulating seawater intrusion to a coastal karst aquifer with a conduit system.

58 GEOSCIENCES↗
DOE OSTI2019

Hydrogeomorphic controls on soil carbon composition in two classes of subalpine wetlands

Wetlands play a vital role in terrestrial carbon (C) sequestration, but the sensitivity of their C stocks to disturbance remains uncertain, requiring enhanced understanding of the processes that govern C storage and removal. The unique conditions in wetlands from different hydrogeomorphic (HGM) classes likely regulate the cycling, storage and vulnerabilities of wetland soil C stocks. To determine how differences in hydrogeomorphic setting influence soil organic carbon (SOC) processing, in this study we compared C content and composition between depressional and slope wetlands located in the Colorado Rocky Mountains. Isolated depressional wetlands were characterized by seasonally declining water tables, slow discharge, high clay content, and thick organic horizons. Slope wetlands received perennial groundwater inputs and had coarser soil textures and thinner organic horizons. Seasonal snowmelt inputs coupled with low hydrologic discharge and higher clay content in depressional wetlands were predicted to sustain anoxic conditions, leading to high SOC content and chemically reduced C compounds. Depressional wetland soils had higher SOC content at depth and higher porewater DOC concentrations compared to slope wetland soils. Solid-state 13 C nuclear magnetic resonance spectroscopy demonstrated that aliphatic compounds were the dominant SOC component in depressional wetlands compared to aromatic C forms in the slope wetlands. The higher prevalence of aliphatic carbon in depressional wetland soils suggests that stored SOC is protected by anaerobic conditions to a greater extent than in the slope wetlands, and that this SOC may be more vulnerable to drying and oxic conditions associated with wetland drainage and climate change.

13C NMR↗
DOE OSTI2022

Boundary characterization using 3D mapping of geometrically necessary dislocations in AM Ta microstructure

Additive manufacturing (AM) of high strength metallic materials produces microstructures and defects that deviate substantially from those created through conventional manufacturing methods. It has recently been demonstrated that with application of extreme energy densities, a high-temperature refractory metal, tantalum (Ta), can be printed to a fully dense state with exceptionally low porosity. Here we employ a combination of three-dimensional electron backscattered diffraction (EBSD) TriBeam technology and crystallographic geometrically necessary dislocation (GND) theory to characterize the microstructure and defect boundaries of this unusual AM product. Two-dimensional (2D) EBSD and these three-dimensional (3D) measurements indicate that the microstructure of AM Ta is highly oriented <111> along the build direction, yet at the same time contains large crystallographic orientation gradients that span mm’s across the build. Crystallographic GND density analysis of the 3D microstructure reveals that highly misoriented subboundaries exist within this strongly textured microstructure that have large dislocation densities of 1×10 16 m –2 , just as large as those comprising the high-angle grain boundaries (HAGBs) in the same material. The 3D crystallographic GND density mapping reveals these subboundaries are part of a complex, finely spaced network that extends throughout the entire microstructure. Here, the orientation of these boundaries can be related to the scan strategy used during printing. TEM measurements corroborate an extremely high dislocation density at the microscale and indicate a cell-like dislocation network structure existing in the AM Ta at the sub-μm scale.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Electron beam irradiation effects on bulk metals: a comparative study of polycrystalline versus single-crystalline structures

This study investigates the effects of electron beam (e-beam) irradiation on the mechanical and structural properties of eight bulk metallic samples, comprising both polycrystalline (PC) and single-crystalline (SC) forms of Ni, Cr, V, and Ti. These metals were evaluated as potential candidates for beam exit windows in high-power (MW-class) particle accelerators. The primary objective is to identify metals capable of withstanding the conditions of high-power/MW-class e-beam accelerators and serve effectively as exit windows. Selection criteria were based on each metal’s intrinsic properties, power dissipation capability, and irradiation-induced changes in mechanical behavior, including hardness, elastic modulus, and defect density. Comprehensive characterization was conducted using field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDS), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and nanoindentation, performed both before and after exposure to a ~¿66 kGy dose from a 10 MeV e-beam accelerator. Results revealed that e-beam irradiation induced hardening in PC Ni, whereas PC Ti, commonly used in beam exit windows, exhibited softening. The observed softening in PC Ti is attributed to grain coarsening, elongation, and the formation of twins and twin boundaries, in contrast to the smaller, compressed grains in the pristine (Pr) PC Ti samples, consistent with the Hall–Petch relationship. The stresses due to twinning are small and insignificant in influencing the overall hardening of the PC Ti irradiated sample when compared to the stresses due to the dislocation density. Conversely, SC Ti samples exhibited irradiation-induced hardening. The SC Ti irradiated samples developed additional irradiation-induced modifications in crystallographic texture of (100), (101), (110), (200), (112), (004), and (211) as evidenced from the XRD results, which could probably explain the hardening effect that is caused by irradiation.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Recovery of Kraft Lignin from OPEFB and Using for Lignin–Agarose Hydrogel

Lignins from the spent pulping liquor were normally acquired as waste product of pulp and paper mills. The possibilities of utilizing kraft lignin have yet been developed for commercial innovation. The objectives of this research are to recovery and utilization of lignin from black liquor of oil palm empty fruit bunches (OPEFBs). Kraft lignins from the OPEFBs black liquor were recovered by acidification procedure. They were precipitated at pH 4, 3, and 2 in order that determine the optimum pH for isolation. It can be clearly seen that the best condition of lignin precipitation was at pH 3. It offered the highest yield and purity. The kraft lignin and agarose were utilized as the crude material for the production of lignin–agarose hydrogel. Lignin–agarose hydrogel could be prepared by using epichlorohydrin as the cross-linking agent. The cross-linking occurrence was recognized by FTIR. Physical and chemical properties of hydrogel were investigated. Gel strength of lignin–agarose hydrogel was characterized by texture personal analysis. The results demonstrated that the gel strength increased with increasing of lignin and epichlorohydrin (ECH) in agarose solutions. 5% lignin, 5% agarose and 10 mL ECH contributed the best gel formation and the great mechanical properties. The effect of cross-linking condition on the gel properties, for example, gel hardness and fracturability, was examined.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2018

Investigation on the Current Transport Characteristics of SrTiO{sub 3}/YBa{sub 2}Cu{sub 3}O{sub 7−x} Heterostructure

By the combined use of the sol-gel and pulsed laser deposition methods, the SrTiO{sub 3}/YBa{sub 2}Cu{sub 3}O{sub 7−x} (STO/YBCO) heterostructure was prepared on a LaAlO{sub 3} substrate. XRD results and φ scanning test showed that the prepared STO/YBCO heterostructure had good biaxial texture. Moreover, a Pt electrode was sputtered on the STO/YBCO heterostructure to investigate the current density-voltage (J − V) characteristic curves of STO/YBCO in the 50–300 K temperature range. The results showed that the STO/YBCO heterostructure had good rectifying characteristics. With an applied positive bias voltage smaller than 3.7 V, the current density of the STO/YBCO heterostructure decreased with the decrease of temperature; for higher voltages, on the contrary, the current density increased with the decrease of temperature. When the YBCO experienced superconducting transition, the turn-on voltage (V{sub t}) changed suddenly due to the sudden opening of the superconducting energy gap of YBCO. The V{sub t} variation obtained from the experiment was essentially consistent with the known value of the YBCO superconducting energy gap.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Superconducting Performance, Structure, Microstructure, and Trapped Field of Top-Seeded Melt-Processed Bulk Y{sub 3}Ba{sub 5}Cu{sub 8}O{sub x}

The sintering temperature for the production of Y{sub 3}Ba{sub 5}Cu{sub 8}O{sub 18} (Y-358) preform powders synthesized in sol-gel spontaneous combustion technique was optimized. A large single-grain bulk Y-358 crystal was fabricated employing a top-seeded melt-growth technique utilizing the optimally sintered preform powders (i.e., at 900 {sup ∘}C for 12 h). Structural, microstructural, elemental, and magnetic properties were investigated by means of X-ray diffraction, scanning electron microscopy, and SQUID, respectively. The structural characterization indicated that the sample is highly textured in (00l) direction. The Y-358 phase fractions were estimated in both preform powders and bulk sample using Rietveld refinement. The onset of superconducting transition is observed at 92.5 K, and the curve is very sharp indicative of the high quality of the produced bulk sample. The field dependence of critical current density (J{sub c}) was determined at 77 K, and the self-field J{sub c} was found to be ∼26 kA/cm{sup 2}. A magnetic field of 0.27 T was trapped by the sample at 77 K.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

A Low-Cost Fabrication Technique for the Growth of Single-Domain GdBCO Bulk Superconductor from Raw Metal Oxides

A single-domain GdBCO bulk superconductor is usually fabricated using a mixture of pre-reacted precursor powders (including GdBa{sub 2}Cu{sub 3}O{sub 7−δ} and Gd{sub 2}BaCuO{sub 5}) by the top-seeded melt texture growth (TSMTG) process. However, the synthesis of pure-phase precursor powder by the solid-state sintering reaction can not only consume time for weeks but also prolong the fabrication process and can lead to a low-efficiency and high-cost process. In this paper, we reported the successful growth of single-domain GdBCO bulk superconductors by the top-seeded metallic oxide melt growth (TS-MOMG) process in which the raw materials of Gd{sub 2}O{sub 3}, BaO, and CuO, the three different metallic oxides, are just involved to fabricate the single-domain GdBCO bulk superconductors. After detailed investigations in the morphology, levitation force, trapped magnetic field, and critical temperature of the grown samples with different ratios, it was found that the simplified precursor-phase source can be used to fabricate the single-domain GdBCO bulk superconductors more efficiently, which can combine the crystal growth procedure and greatly economize the preparation cost and the time to the most extent.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Laser Source Influence on the Preferential Growth and the Inversion Degree in Pulsed Laser CoFe{sub 2}O{sub 4} Films

A comparative study between cobalt ferrite films deposited by pulsed laser deposition as a function of the laser sources, 355 nm (Nd:YAG) and 248 nm (KrF excimer), on amorphous quartz (AQ) and < 100 > -oriented silicon wafer (SW) at different temperatures (650–800 {sup ∘}C) is presented. Also, a quantitative estimation of the preferential crystalline growth orientation as laser source function was made by means of Lotgering factor and Harris texture coefficient, which were obtained from XRD patterns. The inversion degree in spinel-type structure for cobalt ferrite films was calculated through a deconvolution in Raman spectra, where the band A{sub 1g} vibrating modes in tetrahedral sites were associated with Fe and Co sites (687 and 611 cm{sup −1}, respectively). Additionally, saturation magnetization was also calculated from the inversion degree obtained from deconvolution of the Raman spectra in CoFe{sub 2}O{sub 4} films, being compared with experimental results, which is in a good agreement with cobalt ferrite bulk, and we also correlated the preferential growth and the particle size with increment of the coercive field.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

A Comparative Study on Microstructures, Magnetic Features and Morphologies of Ternary Fe–Co–Ni Alloy Thin Films Electrochemically Fabricated at Different Deposition Potentials

Electrochemically fabricated ternary Fe–Co–Ni alloy thin films with different chemical compositions were obtained at different deposition potentials. An increase in the deposition potential increased the Ni content while it decreased the Co and Fe contents in the film structure. An anomalous co-deposition behaviour was also studied and the anomalous order of co-deposition was found to be Fe–Ni > Co–Ni > Fe–Co irrespective of deposition potential. Structural characterizations confirmed the presence of single face-centred cubic (fcc) phase structure with [111] preferred crystallographic orientation for all films. The size of the crystallites and the texture degree increased with increasing applied deposition potential. Smaller globular particles occurred on the surface structure of the film fabricated at higher deposition potentials compared to those grown at lower deposition potentials. A decrement detected in the coercive field with increasing applied deposition potential was related to the variations occurred in the chemical composition and the particle size.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Magnetic Mesocellular Foam Functionalized by Curcumin for Potential Multifunctional Therapeutics

The study investigates curcumin/SPIONs hybridized mesocellular foam type silica for potential dual purpose of drug delivery (curcumin) and magnetic resonance imaging. Magnetization capability and curcumin release was assessed for different structured silica such as spherical silica (Q-10), Si-MCM-41, Si-SBA-16, mesocellular foam (MSU-Foam), Si-KIT-6, ULPFDU-12, and silicalite. The phase, textural, and morphological variation was systematically scrutinized using various physico-chemical techniques. Ten weight percent SPIONs loading was found to generate magnetically active SPIONs in the following order: Q-10 (1.44 emu/g) > SBA-16 (0.80 emu/g) > MSU-Foam (0.24 emu/g) > Si-MCM-41 (0.07 emu/g) > Si-KIT-6 (0.07 emu/g) > silicalite (0.08 emu/g), respectively. The iron oxide dispersion, specific surface area, and porosity play a major role in various structured silicas. MSU-Foam with wormhole structure showed highest specific surface area occupation of SPIONs (73%). The presence of interconnected porosity of foam tends to generate external agglomeration of SPIONs (7–18 nm) at the pore surface contributing to expansion of pore sizes from 16.4 to 40.2 nm. The SPIONs over spherical micron-sized silica Q-10 showed the formation of large nanoclusters (10–25 nm). Thirty to 390 μg/ml of curcumin was loaded over silica and SPIONs/silica structured hybrid, and drug release was studied at pH 5.6 for 72 h. SPIONs/MSU-Foam with less magnetization showed the highest cumulative curcumin release (53.2%), while Q-10 spherical silica with high magnetization property showed less cumulative release of curcumin (12%).

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

Microstructure and Magnetic Properties of Exchange-Coupled Co{sub 72}Pt{sub 28}/Pt/Co{sub 81}Ir{sub 19} Composite Media for Perpendicular Magnetic Recording

In this work, we report the investigation of microstructure and magnetic properties of the Co{sub 72}Pt{sub 28}/Pt/Co{sub 81}Ir{sub 19} exchange-coupled composite (ECC) media using soft-layer (SL) of Co{sub 81}Ir{sub 19} with negative magnetocrystalline anisotropy (MA). Our TEM images show that the hard-layer (HL) exhibits a columnar type microstructure with well-isolated grains and the exchange-coupled SL with hcp-structure show the same texture. Strong coupling of the two layers have been evidenced by the magnetic characterization for all the studied films with Pt inter-layer thickness ranging from 0 to 2 nm. Importantly, these ECC media films have much lower coercivities and much higher thermal stabilities in the favor of high-density magnetic recording.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Influence of Packing Atmosphere on the Microstructures and Transport Properties of Bi-2223/AgAu Tapes

Oxygen partial pressure was the key factor to tune the phase evolution mechanism of Bi-2223 system. In order to investigate the influence of packing atmosphere on the phase formation rate of Bi-2223, microstructures‚ and the current capacity of final tapes‚ 37-filamentary Bi-2223/AgAu tapes were fabricated by powder-in-tube (PIT) process, and the powder packing process operated in the glove box under different atmosphere of pure O{sub 2}‚ air, and N{sub 2}–7.5%O{sub 2}, with the oxygen partial pressure of 100%‚ 25%, and 7.5%, respectively. With different packing atmosphere, the phase formation rate of Bi-2223 increased obviously during the first heat treatment process (HT1). While, based on the same HT1 process, the maximum Bi-2223 phase content was obtained in the tapes with packing atmosphere of N{sub 2}–7.5%O{sub 2}‚ which should be attributed to the suitable Bi-2223 content and distribution. Due to the improvement of superconducting phase content and better texture structure, the critical current density increased with decreasing oxygen partial pressure of packing atmosphere and the maximum value of 19.9 kA/cm{sup 2} was reached. Moreover‚ the in-field current capacities of these Bi-2223/AgAu tapes have also been enhanced with low oxygen partial pressure in packing atmosphere, attributed to the improvements of intergrain connectivity.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2026

Characterizing microscale signatures in uranium ore concentrates using electron probe microanalyzer

Impurities in uranium ore concentrates (UOCs) serve as forensic signatures of processing history and origin. Here, this study utilizes Electron Probe Microanalyzer (EPMA) to characterize microscale compositional and textural features in individual UOC particles from both commercial and bench-scale production. At the particle scale, multiple internal phases with distinct morphologies, chemical signatures, and stoichiometries are documented. Our data shows that chemical impurities are heterogeneously distributed within single particles and among particles within a sample. These microscale heterogeneities correlate with known processing histories, indicating that microscale signatures of early fuel cycle materials can provide valuable information for nuclear forensic material analysis.

organic↗
DOE OSTI2019

Particle filter-based modulation domain infrared targets tracking

Faced with problems of low contrast, poor SNR, and relatively complicated tracking environment, stable infrared target tracking is worth researching for its many potential applications. In this paper, instead of traditional target tracking in the pixel domain, we propose a sampling importance resampling (SIR) particle filter method with indirect velocity measurements to track infrared targets in the modulation domain. The dominant amplitude modulation (AM) features used for tracking is extracted by decomposing the input image using an 18-channel Gabor filter bank followed by the application of the dominant component analysis approach. The dominant AM modulation features provide a significant partial texture characteristic of the target which can be separated from background with better discrimination. To take advantage of observed kinematics, we utilize the augmented state vector with indirect velocity information via combining the measurements of velocity in adjacent frames to the SIR particle filter framework, which weakens weights of particles with bad velocity estimates but still having association with the cluttered background or other moving objects. A dynamic template update strategy is also provided to prevent the tracker from appearance model drift. Experiments indicate that the proposed method is effective for raising the tracking accuracy compared with other tracking methods.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗