Motion Compression Research Articles

Object based watermarking for H.264/AVC video resistant to rst attacks

In this paper, a compressed domain video watermarking scheme is proposed which embeds the watermark in the homogeneous moving object within a shot of video sequence to resist geometric attacks such as rotation, scaling etc. Intuitively, object based watermarking results low payload and has the least impact on visual quality since the object area is generally small and highly textured. The proposed work has two main contributions, firstly, an existing compressed domain motion coherent block detection algorithm [7] is extended to detect the moving objects within a video shot and secondly, a watermarking scheme has been proposed by embedding within the moving objects to resist RST attacks. A comprehensive set of experiments has been carried out to justify the applicability of the proposed scheme over the existing literature.

An analytic method for two-dimensional wall motion and product isentrope from the detonation cylinder test

The cylinder test provides a measurement of detonation product’s ability to perform work on adjacent material. Historically, direct numerical simulation has been required to derive the product energy content and isentrope from experiments of cylinder expansion driven by detonation products. One-dimensional analytic methods have not been able to accurately recover these parameters when the cylinder motion is compressible, exhibiting shocks. For incompressible cylinder motion, analytic one-dimensional approximations more accurately recover the isentrope, but still only approximate the two-dimensional cylinder motion and energy. This work provides a fully two-dimensional model that recovers the exact outer cylinder shape from experimental measurements. The inner cylinder shape and product isentrope are also exactly recovered in the limit of incompressible case motion. An alternate methodology also approximates the inner case shape and isentrope for compressible case motion, effectively allowing accurate isentrope determination for any cylinder test. The isentrope derived from a PBX 9502 cylinder test with compressible motion is shown to agree well with a reference isentrope. The errors associated with the one-dimensional flow assumption are also quantified. The incompressible case model can be used to estimate case shape and velocity from a given isentrope, providing a maximum fragment velocity.

ICD lead failure detection through high frequency impedance.

Abrasion-induced insulation breach is a common failure mode of silicone-body, transvenous, implantable cardioverter defibrillator leads. It is caused either by external compression or internal motion of conducting cables. The present method of monitoring lead integrity measures low frequency conductor impedance. It cannot detect insulation failures until both the silicone lead body and inner fluoropolymer insulation have been breached completely, exposing conductors directly to blood or tissue. Thus the first clinical presentation may be either failure to deliver a life-saving shock or painful, inappropriate shocks in normal rhythm. We present a new method for identifying lead failure based on high frequency impedance measurements. This method was evaluated in 3D electromagnetic simulation and bench testing to identify insulation defects in the St. Jude Medical Riata® lead, which is prone to insulation breach.

Global existence and convergence rates for the smooth solutions to the compressible magnetohydrodynamic equations in the half space

BackgroundWith the characteristics of low pollution and low energy consumption, the magnetohydrodynamics has made widely attention. This paper provides the standard energy method to solve the magnetohydrodynamic equations (MHD) in the half space ℝ + 3 . It proves the global existence for the compressible (MHD) by combining the careful a priori estimates and the local existence result. This study also considers the large time behaviors of the solutions.ResultsThe interactions between the viscous, compressible fluid motion and the magnetic field are modeled by the magnetohydrodynamic system which describes the coupling between the compressible Navier-Stokes equations and the magnetic equations. This study has applied the analytical method to obtain the solutions to (MHD) in ℝ + 3 . It proves that under the assumption that the initial data are close to the constant state, the global existence of smooth solutions can be established. Moreover, the various decay rates of such solutions in Lp-norm with 2≤p≤+∞ and their derivatives in L2-norm can also be derived from combining the decay estimates of the linearized system and the energy method.ConclusionsThis study demonstrates that the global existence and the decay rates for the compressible (MHD) can be established under the similar initial assumptions as for the compressible Navier-Stokes equations. Especially, the results suggest that if the initial velocity is small, the velocity decays at a certain rate. This implies that only under the initial assumption that the data are large, it may reach the requirements of (MHD) power generation, which can be used to achieve the value of industrial application and environmental protection.

ALIGNMENT OF THE SCALAR GRADIENT IN EVOLVING MAGNETIC FIELDS

We conduct simulations of turbulent mixing in the presence of a magnetic field, grown by the small-scale dynamo. We show that the scalar gradient field, $\nabla C$, which must be large for diffusion to operate, is strongly biased perpendicular to the magnetic field, ${\mathbf B}$. This is true both early-on, when the magnetic field is negligible, and at late times, when the field is strong enough to back react on the flow. This occurs because $\nabla C$ increases within the plane of a compressive motion, but ${\mathbf B}$ increases perpendicular to it. At late times the magnetic field resists compression, making it harder for scalar gradients to grow and likely slowing mixing.

The vertical structure and kinematics of grand design spirals

Abstract We use an N-body simulation to study the 3D density distribution of spirals and the resulting stellar vertical velocities. Relative to the disc's rotation, the phase of the spiral's peak density away from the mid-plane trails that at the mid-plane. In addition, at fixed radius the density distribution is azimuthally skewed, having a shallower slope on the trailing side inside corotation and switching to shallower on the leading side beyond corotation. The spirals induce non-zero average vertical velocities, 〈Vz〉, as large as 〈Vz〉 ∼ 10–20 km s−1, consistent with recent observations in the Milky Way. The vertical motions are compressive (towards the mid-plane) as stars enter the spiral, and expanding (away from the mid-plane) as they leave it. Since stars enter the spiral on the leading side outside corotation and on the trailing side within corotation, the relative phase of the expanding and compressive motions switches sides at corotation. Moreover, because stars always enter the spiral on the shallow density gradient side and exit on the steeper side, the expanding motions are larger than the compressing motions.

Effect of Cervical Kyphotic Deformity Type on the Motion Characteristics and Dynamic Spinal Cord Compression

Retrospective analysis of kinematic magnetic resonance images. To provide baseline data on the segmental angular and translational motion of the degenerated cervical spine by subtype of kyphotic cervical deformity and to elucidate the relationship between motion and degree of spinal cord compression. Kyphotic deformities of the cervical spine are relatively common and are classified as either global or focal. Nevertheless, the effects of kyphotic subtype on cervical segmental motion and degree of spinal cord compression are unknown. A total of 1171 symptomatic patients (618 females, 553 males) underwent cervical kinematic magnetic resonance imaging in the neutral, flexion, and extension positions. Cervical spines demonstrating kyphosis were included and classified into 3 groups: (1) "global kyphotic deformity" (C-type) (n = 54); (2) "sigmoid deformity" (S-type) with kyphotic upper and lordotic lower cervical segments (n = 29); and (3) "reverse sigmoid deformity" (R-type) with lordotic upper and kyphotic lower cervical segments (n = 39). Translational motion, angular motion, and degree of spinal cord compression were evaluated for each cervical level along with the changes associated with flexion and extension. In the C- and R-types, angular motion with extension was increased in the upper cervical spine, where there was kyphosis; when compared with the S-type, in which there was lordosis in the upper segments. The results were opposite for flexion angular motion. R-type displayed more translational motion at C3-C4 and C5-C6. Degree of static spinal cord compression of R-type was higher than the others at C3-C4. The dynamic spinal cord compression increased in extension more than flexion in all subtypes. Cervical spine studies that aim to investigate kyphotic deformities should make efforts to discern the different subtypes of kyphotic deformities to more accurately characterize and study the effects that the sagittal alignment has on the kinematics of the spine and the degree of spinal cord compression.

Bending and breathing modes of the Galactic disc

We explore the hypothesis that a passing satellite or dark matter subhalo has excited coherent oscillations of the Milky Way's stellar disk in the direction perpendicular to the Galactic midplane. This work is motivated by recent observations of spatially dependent bulk vertical motions within ~ kpc of the Sun. A satellite can transfer a fraction of its orbital energy to the disk stars as it plunges through the Galactic midplane thereby heating and thickening the disk. Bulk motions arise during the early stages of such an event when the disk is still in an unrelaxed state. We present simple toy-model calculations and simulations of disk-satellite interactions, which show that the response of the disk depends on the relative velocity of the satellite. When the component of the satellite's velocity perpendicular to the disk is small compared with that of the stars, the perturbation is predominantly a bending mode. Conversely, breathing and higher order modes are excited when the vertical velocity of the satellite is larger than that of the stars. We argue that the compression and rarefaction motions seen in three different surveys are in fact breathing mode perturbations of the Galactic disk.

INVESTIGATIONS OF PROTOSTELLAR OUTFLOW LAUNCHING AND GAS ENTRAINMENT: HYDRODYNAMIC SIMULATIONS AND MOLECULAR EMISSION

We investigate protostellar outflow evolution, gas entrainment, and star formation efficiency using radiation-hydrodynamic simulations of isolated, turbulent low-mass cores. We adopt an X-wind launching model, in which the outflow rate is coupled to the instantaneous protostellar accretion rate and evolution. We vary the outflow collimation angle from $\theta$=0.01-0.1 and find that even well collimated outflows effectively sweep up and entrain significant core mass. The Stage 0 lifetime ranges from 0.14-0.19 Myr, which is similar to the observed Class 0 lifetime. The star formation efficiency of the cores spans 0.41-0.51. In all cases, the outflows drive strong turbulence in the surrounding material. Although the initial core turbulence is purely solenoidal by construction, the simulations converge to approximate equipartition between solenoidal and compressive motions due to a combination of outflow driving and collapse. When compared to a simulation of a cluster of protostars, which is not gravitationally centrally condensed, we find that the outflows drive motions that are mainly solenoidal. The final turbulent velocity dispersion is about twice the initial value of the cores, indicating that an individual outflow is easily able to replenish turbulent motions on sub-parsec scales. We post-process the simulations to produce synthetic molecular line emission maps of $^{12}$CO, $^{13}$CO, and C$^{18}$O and evaluate how well these tracers reproduce the underlying mass and velocity structure.

Compressive Feedback-Based Motion Control for Nanomanipulation—Theory and Applications

Conventional scanning probe microscopy (SPM)-based nanomanipulations always have to face scanner accuracy problems such as hysteresis, nonlinearity, and thermal drift. Although some scanners consist of internal position sensors, the sensitivity is not high enough to monitor high-resolution nanomanipulations. Additionally, once the scan size decreases to a nanolevel such as less than 100 nm, the noise brought by sensors is large enough to affect the performance of the closed-loop motion control system. In this paper, a non-vector space control strategy based on compressive feedback is proposed in order to improve the accuracy of SPM-based nanomanipulations. In this approach, local images (or compressive data) are used as both the reference input and feedback for a non-vector space closed-loop controller which considers the local image (or compressive data) as a set. The controller is designed in non-vector space, and it requires no prior information on features or landmarks which are widely used in traditional visual servoing. In this paper, the atomic force microscopy is used as an example of SPM to implement the non-vector space control strategy for nanomanipulations. The motivation of designing such a non-vector space controller is to solve the accuracy problem in nanomanipulation. Without this technique, the SPM-based nanomanipulations, such as nanomeasurement and nanosurgery, are difficult to conduct, with accuracy controlled under several nanometers. In order to illustrate the contributions and potential applications of this non-vector controller, at the end of this paper, an application of carbon nanotube local electrical property characterization based on a non-vector space motion control is shown to clearly verify the concept. Compared with other research in the local electrical property characterization, the non-vector space controller can ensure that the measurement accuracy (position error) is controlled within a few nanometers, which also ensures the reliability of measurement results. Additionally, this non-vector space control method can be implemented into any kind of SPM to realize a real-time control for nanomanipulation such as nanofabrication and nanoassembly.

Conformational Compression and Barrier Height Heterogeneity in theN-Acetylglutamate Kinase

The role of motions in the catalytic cycle of an enzyme is the subject of much debate. Crystallographic results for the enzyme N-acetyl-l-glutamate kinase (NAGK), which is a suitable target for antibacterial drugs, suggest that a conformational compression of the active site favors catalysis. We have used a QM/MM scheme to compute energy profiles of the phosphoryl transfer reaction for 20 conformations of NAGK, starting from four crystal structures that represent different stages of the catalytic process. All paths show a common associative mechanism but with a wide range of barrier heights. The position of several active site residues and water molecules are found to determine the energetic barrier of each conformation, as revealed by principal component and partial least-squares chemometric analyses. In particular, conformations in which the two substrates have a shorter distance separation and a more linear mutual orientation tend to have lower energetic barriers, thus supporting the putative role of conformational compressive motions in catalysis. Interestingly, these motions are the same that lead to opening of the active site, which molecular dynamics simulations indicate is a fast process when the enzyme is free of substrates. Despite the lack of extended sampling, the energy barrier we calculate for the chemical step lies significantly below the apparent energetic barrier derived from experiment. Although not conclusive, this result supports a previous hypothesis, also derived from experiment, that conformational motions, rather than the chemical step, are rate limiting.

TURBULENCE IN THE INTERGALACTIC MEDIUM: SOLENOIDAL AND DILATATIONAL MOTIONS AND THE IMPACT OF NUMERICAL VISCOSITY

We use a suite of cosmological hydrodynamic simulations, run by two fixed grid codes, to investigate the properties of solenoidal and dilatational motions of the intergalactic medium (IGM), and the impact of numerical viscosity on turbulence in a LCDM universe. The codes differ only in the spatial difference discretization. We find that (1) The vortical motion grows rapidly since $z=2$, and reaches $\sim 10 km/s -90 km/s$ at $z=0$. Meanwhile, the small-scale compressive ratio $r_{CS}$ drops from 0.84 to 0.47, indicating comparable vortical and compressive motions at present. (2) Power spectra of the solenoidal velocity possess two regimes, $\propto k^{-0.89}$ and $\propto k^{-2.02}$, while the total and dilatational velocity follow the scaling $k^{-1.88}$ and $k^{-2.20}$ respectively in the turbulent range. The IGM turbulence may contain two distinct phases, the supersonic and post-supersonic phases. (3) The non-thermal pressure support, measured by the vortical kinetic energy, is comparable with the thermal pressure for $\rho_b \simeq 10-100$, or $T <10^{5.5} K$ at $z=0.0$. The deviation of the baryon fraction from the cosmic mean shows a preliminary positive correlation with the turbulence pressure support. (4) A relatively higher numerical viscosity would dissipate both the compressive and vortical motions of the IGM into thermal energy more effectively, resulting in less developed vorticity, remarkably shortened inertial range, and leading to non-negligible uncertainty in the thermal history of gas accretion. Shocks in regions outside of clusters are significantly suppressed by numerical viscosity since $z=2$, which may directly cause the different levels of turbulence between two codes.

Efficient processing of transportation surveillance videos in the compressed domain

Video surveillance is used extensively in intelligent transportation systems to enforce laws, collect tolls, and regularize traffic flow. Benefits to society include reduced fuel consumption and emissions, improved safety, and reduced traffic congestion. These video cameras installed at traffic lights, highways, toll booths, etc., continuously capture video and hence generate a vast amount of data that are stored in large databases. The captured video is typically compressed before being transmitted and/or stored. While all the archived information is present in the compressed video, most current applications operate on uncompressed video. The aim is to improve the efficiency of processing by utilizing features of the compression process and the compressed video stream. Key methods that are employed involve intelligent selection of reference frames (I-frames) and exploitation of the compression motion vectors. Although specific applications in the transportation imaging domain are presented, the methods proposed here can generally impact the ability to mine vast amounts of video data for usable information in many diverse settings. Applications presented include rapid search for target vehicles (Amber Alert, Silver Alert, stolen car, etc.), vehicle counting, stop sign/light enforcement, and vehicle speed estimation.

Strong magnetic fields and large rotation measures in protogalaxies from supernova seeding

We present a model for the seeding and evolution of magnetic fields in protogalaxies. Supernova (SN) explosions during the assembly of a protogalaxy provide magnetic seed fields, which are subsequently amplified by compression, shear flows and random motions. We implement the model into the MHD version of the cosmological N-body / SPH simulation code GADGET and we couple the magnetic seeding directly to the underlying multi-phase description of star formation. We perform simulations of Milky Way-like galactic halo formation using a standard LCDM cosmology and analyse the strength and distribution of the subsequent evolving magnetic field. A dipole-shape divergence-free magnetic field is injected at a rate of 10^{-9}G / Gyr within starforming regions, given typical dimensions and magnetic field strengths in canonical SN remnants. Subsequently, the magnetic field strength increases exponentially on timescales of a few ten million years. At redshift z=0, the entire galactic halo is magnetized and the field amplitude is of the order of a few $\mu$G in the center of the halo, and 10^{-9} G at the virial radius. Additionally, we analyse the intrinsic rotation measure (RM) of the forming galactic halo over redshift. The mean halo intrinsic RM peaks between redshifts z=4 and z=2 and reaches absolute values around 1000 rad m^{-2}. While the halo virializes towards redshift z=0, the intrinsic RM values decline to a mean value below 10 rad m^{-2}. At high redshifts, the distribution of individual starforming, and thus magnetized regions is widespread. In our model for the evolution of galactic magnetic fields, the seed magnetic field amplitude and distribution is no longer a free parameter, but determined self-consistently by the star formation process occuring during the formation of cosmic structures.

Three-dimensional numerical models of flat slab subduction and the Denali fault driving deformation in south-central Alaska

Early theories of plate tectonics assumed plates were rigid with deformation limited to within a few tens of kilometers of the plate boundary. However, observations indicate most continental plates defy such rigid behavior with deformation extending over 1000 kilometers inboard. We construct three-dimensional (3D) numerical models of the boundary between the Pacific and North American plates in Alaska to investigate the relative controls of flat slab subduction, continental scale faulting, and a non-linear rheology on deformation in the overriding plate. The models incorporate a realistic slab shape based on seismicity and seismic tomography and a variable thermal structure for both the subducting and overriding plates based on geologic and geophysical observables. The inclusion of the Denali fault in the models allows for the portion of south-central Alaska between the Denali fault and the trench to partially decouple from the rest of North America, forming an independently moving region that correlates to what has been described from geologic and geodetic studies as the Wrangell block. The motion of the Wrangell block tracks the motion of the flat slab in the subsurface indicating the subducting plate is driving the motion of the Wrangell block. Models using a composite (Newtonian and non-Newtonian) viscosity predict compressional motion along the northern bend in the Denali fault, consistent with thermochronologic data that show significant late Neogene exhumation in the central Alaska Range, including at Mt. McKinley, the tallest mountain in North America. These 3D numerical models of the Pacific–North American margin in Alaska show the subducting slab is the main driver of overriding plate deformation in south-central Alaska and combined with the Denali fault can reproduce several first order tectonic features of the region including the motion of the Wrangell block, uplift in the central Alaska Range, subsidence in the Cook Inlet-Susitna Basins, and upwelling at the slab edge beneath the Wrangell volcanics.

Large-scale radio continuum properties of 19 Virgo cluster galaxies

Deep scaled array VLA 20 and 6cm observations including polarization of 19 Virgo spirals are presented. This sample contains 6 galaxies with a global minimum of 20cm polarized emission at the receding side of the galactic disk and quadrupolar type large-scale magnetic fields. In the new sample no additional case of a ram-pressure stripped spiral galaxy with an asymmetric ridge of polarized radio continuum emission was found. In the absence of a close companion, a truncated HI disk, together with a ridge of polarized radio continuum emission at the outer edge of the HI disk, is a signpost of ram pressure stripping. 6 out of the 19 observed galaxies display asymmetric 6cm polarized emission distributions. Three galaxies belong to tidally interacting pairs, two galaxies host huge accreting HI envelopes, and one galaxy had a recent minor merger. Tidal interactions and accreting gas envelopes can lead to compression and shear motions which enhance the polarized radio continuum emission. In addition, galaxies with low average star formation rate per unit area have a low average degree of polarization. Shear or compression motions can enhance the degree of polarization. The average degree of polarization of tidally interacting galaxies is generally lower than expected for a given rotation velocity and star formation activity. This low average degree of polarization is at least partly due to the absence of polarized emission from the thin disk. Ram pressure stripping can decrease whereas tidal interactions most frequently decreases the average degree of polarization of Virgo spiral galaxies. We found that moderate active ram pressure stripping has no influence on the spectral index, but enhances the global radio continuum emission with respect to the FIR emission, while an accreting gas envelope can but not necessarily enhances the radio continuum emission with respect to the FIR emission.

Fibrin glue as a non-invasive outpatient treatment for post-arthroscopic knee seromas

Post-surgical seromas and cysts have been reported across many surgical subspecialties including orthopaedics. Treatments include both invasive surgical approaches and more recently reported non-invasive techniques. Non-invasive approaches currently include compressive wrapping, vasopneumatic cryotherapy, and motion exercises. Persistent lesions have been treated with talc or doxycycline sclerodesis. This case presents a patient with a post-arthroscopic seroma that was treated with fibrin glue in an outpatient setting. Fibrin glue has not been reported in the post-arthroscopy outpatient setting to address cystic lesions. This case suggests a viable non-invasive treatment option for these lesions. Level of evidence V.

Bayesian speckle tracking. Part I: an implementable perturbation to the likelihood function for ultrasound displacement estimation.

Accurate and precise displacement estimation has been a hallmark of clinical ultrasound. Displacement estimation accuracy has largely been considered to be limited by the Cramer-Rao lower bound (CRLB). However, the CRLB only describes the minimum variance obtainable from unbiased estimators. Unbiased estimators are generally implemented using Bayes' theorem, which requires a likelihood function. The classic likelihood function for the displacement estimation problem is not discriminative and is difficult to implement for clinically relevant ultrasound with diffuse scattering. Because the classic likelihood function is not effective, a perturbation is proposed. The proposed likelihood function was evaluated and compared against the classic likelihood function by converting both to posterior probability density functions (PDFs) using a noninformative prior. Example results are reported for bulk motion simulations using a 6λ tracking kernel and 30 dB SNR for 1000 data realizations. The canonical likelihood function assigned the true displacement a mean probability of only 0.070 ± 0.020, whereas the new likelihood function assigned the true displacement a much higher probability of 0.22 ± 0.16. The new likelihood function shows improvements at least for bulk motion, acoustic radiation force induced motion, and compressive motion, and at least for SNRs greater than 10 dB and kernel lengths between 1.5 and 12λ.

A proficient wavelet-based video encoder through the motion estimation algorithm

In several multimedia applications, image and video coding plays a significant role. In many applications, sceneries such as broadcast services over satellite and terrestrial channels, digital video storage, wires and wireless conversational services and digital video communication are used. It is not possible to store full digital video without processing. Video compression reduces the data used to represent digital video images and is a combination of spatial image compression and temporal motion compensation. The main aim of our research is to develop an efficient video compression system. The proposed system consists of three steps. At first, wavelet decomposition is applied to the I–frame and the resulting coefficients are quantised using the listless SPECK (LSK) algorithm. In the next step, motion estimation is done using adaptive rood search with the spatio–temporal correlation method (ARS–ST) and it calculates the distance between the P–frame and I–frame blocks. In the final step, the difference between the original and the predicted P–frame is evaluated and is known as residual. To produce good quality predictive frames, this residual is transmitted along with motion vectors (MVs) and to decrease its size, it is coded using LSK. The proposed video compression technique uses different videos for assessment and by determining the PSNR values, compression efficiency is estimated. By comparing the proposed system with existing systems, it is seen that our system effectively compresses videos with remarkable PSNR measurements.

A Wavelet-Based Video Compression using Adaptive Rood Search with Spatio-Temporal Correlation and LSK

Image and video coding plays a salient role in numerous multimedia applications. Nowadays, digital video communication is adopted in many applications, for example broadcast services over satellite and terrestrial channels, digital video storage, and more. It is impractical for us to store the full digital video without processing. It is well-known that video compression is a process of diminishing the size of data used to depict digital video images, and it is an amalgamation of spatial image compression and temporal motion compensation. The primary intent of our research is to propose a very potent video compression system. Originally, wavelet decomposition is applied to the I-frame and the resulting coefficients are quantized with the aid of Listless SPECK (LSK) algorithm. Secondly, an adaptive rood search with spatio-temporal correlation technique (ARS-ST) is employed for motion estimation and it finds the displacement of the blocks of P-frame from the I-frame. The proposed video compression technique is evaluated by using different videos and the compression efficiency is computed by determining the peak signal to noise ratio (PSNR) values. Also, the efficacy of the proposed system is compared with existent video compression systems. From the comparative study, it can be seen that our proposed system robustly compress the videos with adequate PSNR measurements.