Velocity (Total 84708 Papers Found)

This review deals with the major problems of unattached Gracilaria intensive cultivation in outdoor tanks and ponds. These problems are presented through the main variables affecting the Gracilaria annual yield and the updated solutions evolved. The physical variables include tank and pond structure, seawater characteristics such as velocity, agitation practice, exchange rate, and salinity, light characteristics such as quantity and quality, and temperature modelling. The chemical variables incl ...
’bo new recursive factorizations are developed of the mass matrix for fixed-base and mobile-base manipulators. First, the mass matrix M is shown to have the factorization M = H$M$* H’. This is referred to here as the Newton-Euler factorization because it is closely related to the recursive Newton-Euler equations of motion. This factorization may be the simplest way to show the equivalence of recursive Newton-Euler and Lagrangian manipulator dynamics. Second, the mass matrix is shown to have ...
BACKGROUND Cardiovascular disease is prevalent in type 2 diabetics, and microalbuminuria is associated with cardiovascular disease morbidity. We aimed to investigate the potential association between low-grade albuminuria and arterial stiffness in patients with type 2 diabetes. METHODS Between 2009 and 2013, a retrospective study was performed in 578 patients with type 2 diabetes (339 male patients and 239 female patients) with normal urinary albumin-to-creatinine ratios (ACRs; <30 mg/g) ...
The understanding of electrokinetic transport of fluid or particles in microchannel plays an important role in the design and the optimization of microand nanofluidic devices. Two important electrokinetic phenomena are electro-osmosis and electrophoresis. In order to study these phenomena, the lattice Boltzmann solver is coupled with the iteration solver for the Poisson equation. Using these numerical schemes, the transient behavior of the electro-osmotic flows is investigated for various physic ...
aveolae appear in a multitude of processes encompassing growth regulation andtrafficking. We demonstrate the abundant presence of ESA/reggie-1/flotillin-2,ATP synthase β subunit and annexin V in endothelial caveolae byimmunopurification of caveolae from vascular endothelial membrane. Fiveproteins are abundant in a caveolin-1 protein complex, analyzed by sucrosegradient velocity sedimentation following octyl-β-D-glucopyranosideextraction. Caveolin-1 α interacts with caveolin-1 β, caveolin-2, ...
A procedure has been established for obtaining equivalent circuit parameters for the Brushless Doubly Fed Machine (BDFM), also known as the Brushless Doubly Fed Induction Machine (DFIM), by transforming a reduced coupled-circuit model into a sequence component form. This approach takes advantage of the model reduction procedure’s ability to reduce a complex rotor structure to a single equivalent loop without significant loss of accuracy. An alternative method based on winding factors has also ...
Having already shown its potential of deriving the vector fields representing the ocean-surface advection from sequential 1.1-km-resolution local area coverage (LAC) Advanced Very High Resolution Radiometer (AVHRR) images, the maximum cross-correlation (MCC) technique here is applied to four 4.4-km-resolution global area coverage (GAC) AVHRR images. The resulting three vector fields are compared to the vector fields obtained from the LAC imagery corresponding to the same satellite passages. To q ...
Myelin protein zero gene (MPZ) mutations may account for a small proportion of cases of Charcot-Marie-Tooth disease (CMT). Different MPZ mutations may be associated with different clinical and electrophysiological phenotypes. To expand our understanding of the characteristics of nerve conduction velocity (NCV) in patients with different MPZ mutations, the authors collected and analysed the NCV values from patients with MPZ mutations. The NCVs of fourteen patients from six families carrying MPZ m ...
We introduce the use of quantum dot (QD) nanoparticles for near-surface velocimetry and provide preliminary data to demonstrate its feasibility. Evanescent wave illumination is used to image the motion of water-soluble (CdSe)ZnS QDs with a core size of 6 nm within a region of order 100 nm of a surface . Results are presented for the two in-plane components of the velocity field. With the recent surge of interest in microfluidics and nanofluidics research, various fundamental and practical issues ...
A method for intraoperative measurement of portal blood flow velocity with duplex Doppler ultrasonography in 7 dogs with congenital intrahepatic portosystemic shunts is described. The aims of the study were to determine whether intraoperative ultrasonography was an acceptable alternative to mesenteric portography in such dogs and to identify quantitative portal hemodynamic variables that might correlate with clinical outcome better than portal pressure does. Ultrasonographic measurements did not ...
Image motion estimation using the spatiotemporal approach has largely relied on the constant velocity assumption, and thus becomes inappropriate when the velocity of the imaged scene or the camera changes during the data acquisition time. Using a polynomial or a trigonometric polynomial model for the time variation of the image motion, spatiotemporal algorithms are developed in this paper to handle time-varying (but space-invariant) motion. Under these models, it is shown that time-varying image ...
The effects of radiation reaction on the motion of charged particles are studied in strong electric and magnetic fields with special attention to the vacuum near-field region of an oblique rotator. For strong radiation damping a local velocity field is derived from the Lorentz-Dirac equation, which efficiently describes the motion of electrons and positrons in the whole range of typical pulsar parameters. The velocity field allows to define regions in the inner magnetosphere, where due to the ra ...
Despite the obvious relevance of tactile sensing to robot manipulation, no comprehensive theory exists regarding how to use this information to estimate hand-object state. This paper explores this issue in the context of particle filtering. The paper proposes using measurements of contact positions and velocities for the purposes of estimating the shape and pose of an object held by the robot. The likelihood of position and velocity measurements of manipulator contact surfaces touching the objec ...
This paper presents a nonlinear error model based on the quaternion for the rapid transfer alignment of the inertial navigation system (INS). It allows the large initial misalignment uncertainty. Then, the unscented Kalman filter (UKF) is designed to achieve the nonlinear filtering based on the proposed model, and utilizes the difference in velocity and attitude between the slave and master INS as the measurement variables. This paper analyzes and compares the misalignment estimation error and c ...
This study presents stress analysis of sheave wheel by a finite element analysis model and experimental tests. Simulation of stress field under two kinds of load condition was carried out with ANSYS. The corresponding relationship between stress and load of hoist as well as sheave wheel's phase angle were obtained. Then field experiments of sheave wheel stress under three kinds of conditions, which were no-load, heavy-load and rope-slack, was conducted using the wireless stress monitoring system ...
Fluid motion resulting from the compressional excitation of the cochlear capsule due to bone conduction is examined in this paper. Vibrations of the skull deform the shape of the cochlear capsule and give rise to motion the fluid. A two-dimensional channel having a height to length ratio equal to ε is used to model the cochlea. The cochlear pressure approaches zero the integral equation is solved and the cochlear pressure is expressed as an asymptotic expansion in ε. Rapid spatial variation in ...
Optical coherence tomography (OCT) is a new technology for noninvasive cross-sectional imaging of tissue structure in biological system by directing a focused beam of light at the tissue to be image [Bouma et al., 1995; Jiang et al., 2005; Ryu et al., 2005]. The technique measures the optical pulse time delay and intensity of backscattered light using interferometry with broadband light sources or with frequency swept lasers. It is analogous to ultrasound imaging or radar, except that it uses li ...
The design and scale-up of trickle bed reactors(TBR) depend on key hydrodynamic variables such as reduced liquid saturation and pressure drop, which in turn depend upon parameters such as operating pressure, phase velocity and phase density. Most of the previous studies on quantifying reduced liquid saturation and pressure drop have been conducted under atmospheric pressure, whereas industrial operating pressures are around 20-30 MPa. Therefore, in the present study, using the bed dimensions and ...
The design of a helical flux compression generator, driven by 200 g of high explosives, for basic studies is presented and experimental results are discussed. Generator current and dI/dt are measured with Rogowski coils placed on the load. Both crowbar closure and contact velocity have been successfully simulated with CTH, a three-dimensional finite element hydrodynamic code. The generator's magnetic field structure is briefly discussed and magnetic field probe measurements are presented. ...
Performance monitoring constitutes a key practice to ensure plant profitability, with considerable cost savings related to maintaining maximum fuel efficiency and availability. As shown in this article, gas turbine performance is strongly affected by “natural” parameters such as ambient environmental and load conditions. As such, only systems that use detailed thermodynamic models of the gas turbine and its components are capable of correctly separating these “natural” effects from actua ...
BACKGROUND AND PURPOSE Transcranial Doppler sonography (TCD) can evaluate noninvasively the blood flow velocities and patency of the main trunk of the middle cerebral artery (MCA). Using TCD we evaluated MCA patency and patterns of flow through the circle of Willis in patients with acute stroke. METHODS Patients with symptoms of hemispheric stroke were evaluated with serial TCD tests during admission. The Canadian Neurological Scale was used to assess neurological deficits. In all cases comput ...
We present a new approach to online trajectory planning for target tracking, dynamic grasping and catching. The robot executes a geometric controller { it simply evaluates a nonlinear function which maps the currently measured position and velocity of the object to be grasped into a current desired robot pose. If the robot tracks these setpoints, it is guaranteed to match the object's velocity and acceleration on a speciied grasp surface. We develop a geometric controller which speciies the full ...
By comparing relative rates of supernovae versus formation rates of single radio pulsars, recycled pulsars, binary pulsars and X-ray binaries we put strong limits on the progenitors of radio pulsars and on the requirement of an asymmetry in the supernova. The assumption that radio pulsars are only formed in type Ib and type Ic supernovae from interacting binaries (Iben & Tutukov 1996) breaks down on the implication that in that case either the formation rate of binary pulsars (double neutron sta ...
This paper presents a preliminary report on our application a newly built plenoptic camera to obtain three-dimensional, three-component particle image velocimetry (PIV) on a turbulent boundary layer in a zero pressure gradient (ZPG) and adverse pressure gradient (APG) region of flow. A Stratford ramp was designed and constructed to produce an adverse pressure gradient turbulent boundary layer in the wind tunnel facility at Auburn University. Pressure measurements and 2-D PIV were performed to ch ...
A Tracking-Learning-Detection (TLD) is a tracking framework that decomposes the long-term tracking task into tracking, learning and detection. To improve the tracking accuracy and precision with TLD, the constraint that a target cannot move a significant distance within a short time period with limited velocity is added, and the target displacement in the previous frame analyzed is used to reduce the detection range of the TLD detector. Instead of using the Median Flow Tracker, a K-Nearest Neigh ...
Smolt survival through the Columbia/Snake river hydrosystem and tributaries of the Snake River are evaluated with the XT-model, which describes predator-prey interactions in terms of migration distance and time, temperature, turbidity, and a random encounter velocity between predators and prey. In this formulation, smolt survival depends on both distance traveled and exposure time, and the importance of each depends on the amount and character of predator and prey motions. The model is used to a ...
A novel hybrid region-based and contour-based multiple object tracking model using optical flow based elastic matching is proposed. The proposed elastic matching model is general in two significant ways. First, it is suitable for tracking of both, rigid and deformable objects. Second, it is suitable for tracking using both, fixed cameras and moving cameras since the model does not rely on background subtraction. The elastic matching algorithm exploits both, the spectral features and contour-base ...
Existence of asymmetric features in a passive walker can be the result of environmental and physical parameters such as mass distribution of legs, length of the legs, path slope, and so on. A great part of previous research works relies on the belief that lack of symmetry and equilibrium would amplify phenomena such as bifurcation and chaos and eventually would cause different step lengths and instability in the bipedal system. This paper attempts to analyze the dynamical behavior of an asymmetr ...
This paper proposes a novel flux reversal linear-rotary permanent magnet actuator (FR-LRPMA) with permanent magnets (PMs) mounted on the stator surface. The proposed FR-LRPMA uses only 50% of the PM materials when compared with that of the topology with four-PM poles in a conventional stator pole actuator. The FR-LRPMA provides a pathway for the magnetic field, which is generated by currents in the armature winding, resulting in substantial reduction in the possibility of irreversible demagnetiz ...
Learning to make point-to-point reaching movements in a curl force field was used as a paradigm to explore the system architecture of the human motor adaptive controller. The concept of internal model, a system for predicting behavior of the controlled movements, is divided into a forward and an inverse model. The existence and learning ability of the inverse model in the brain is more straightforward than forward model. I try to ask whether forward mode does play a role in the human control sys ...
This paper presents a new method to generate suboptimal trajectories for serial manipulators in both configuration and Cartesian space. The method is based first on the dissociation of the search of optimal transfer time T from that of optimal trajectory profiles. Kinematic and dynamic constraints can then be treated in an easy manner because most of them can be transformed into bounds on the value of T. In addition, trajectory profiles are generated using trapezoidal velocity profiles that redu ...
This paper investigates the optimization of design parameters to achieve enhanced modulation efficiency and cutoff frequency in AlGaN/InGaN/GaN HEMTs. The frequency dependent current gain of the device is simulated for different AlGaN thicknesses, taking into account the polarization fields and strain effects. The implementation of an underlap junction is discussed and it is demonstrated that the underlap improves the channel velocity so that current gain cutoff frequency-gate length product of ...
The effects of acoustic modes in the penstock on the self-excited oscillation in hydraulic power system were studied by assuming a finite sound velocity in the penstock. The flow in the draft tube is considered to be incompressible assuming that the length of the draft tube is smaller than the wavelength of the oscillation. It was found that various acoustic modes in the penstock can become unstable (amplified) by the diffuser effect of the draft tube or the effect of swirl flow from the runner. ...
In this work we analyze the mean-square error (MSE) of two correlative channel estimators in time-variant channels. Both estimators make use of orthogonal basis functions that approximate the time-variant channel. The first approximation is based on a set of time shifted rectangular basis (RB) functions. The second approximation makes use of Slepian basis (SB) functions. We calculate the number of basis functions that minimize the MSE for the RB-and the SB-approach. Both estimators are designed ...
Eccentric paddle mechanism based on epicyclic gear mechanism (ePaddle-EGM) is a novel locomotion mechanism designed for amphibious robot. The epicyclic gear mechanism is the key component of ePaddle-EGM to perform multiple gaits. In this paper, efficiency of the epicyclic gear mechanism is analyzed. Via the virtual power flow, we characterize how the efficiency relates with the velocity ratio and torque ratio. Two particular conditions verified the proposed efficiency formulas. ...
For classic radars, pulse compression is an important way to improve range and velocity resolution. And phase-coded and frequency-coded signals are two important means to implement pulse compression. In this paper, we analyze the lower bound of delay and Doppler resolutions of radar phase-coded pulse and frequency-coded pulse. The lower bound of the delay-Doppler resolution of phase-coded waveform is obtained. Meanwhile, the delay resolution of radar frequency-coded waveform is discussed and two ...
The integrated nested Laplace approximation (INLA) [Rue et al., 2009] is now a well-known functional approximation algorithm for implementing Bayesian inference in latent Gaussian models but has some limitations: it is unable to handle a high dimensional model parameter θ, and makes a poor approximation when the posterior is multi-modal and the likelihood is highly nonGaussian. Two types of algorithm are proposed to address these limitations: (a) a combination of INLA and Monte Carlo methods an ...
We show that the 5 GHz radio flux of transient ballistic jets in black hole binaries correlates well with the dimensionless black hole spin parameter a∗ estimated via the continuumfitting method. The data suggest that jet power scales either as the square of a∗ or the square of the angular velocity of the horizonΩH . This is the first direct evidence that jets are powered by black hole spin energy. The observed correlation validates the continuum-fitting method of measuring spin. In additio ...
Reliable interpretation of seismic surveys and borehole loggings requires that the seismic velocities and anisotropies of the bedrock are taken into account. There will be discrepancies in estimated reflector locations if one assumes isotropic velocity. Moreover, improved accuracy in determining reflector locations reduces drilling efforts in ore exploration. Our custom-built ultrasonic triaxial anvil setup permits measuring longitudinal (Vp) (1 MHz center frequency) and shear wave (Vs) (1.1 MHz ...
Passive flexibility was found to enhance propulsive efficiency in swimming animals. In this study, we numerically investigate the roles of structural resonance and hydrodynamic wake resonance in optimizing efficiency of a flexible plunging foil. The results indicates that (1) optimal efficiency is not necessarily achieved when the driving frequency matches the structural eigenfrequency; (2) optimal efficiency always occurs when the driving frequency matches the wake resonant frequency of the tim ...
Recently, numerical studies revealed two different scaling regimes of the peak enstrophy Z and palinstrophy P during the collision of a dipole with a no-slip wall [Clercx and van Heijst, Phys. Rev. E 65, 066305, 2002]: Z ∝ Re0.8 and P ∝ Re2.25 for 5 × 102 ≤ Re ≤ 2 × 104 and Z ∝ Re0.5 and P ∝ Re1.5 for Re ≥ 2 × 104 (with Re based on the velocity and size of the dipole). A critical Reynolds number Rec (here, Rec ≈ 2 × 104) is identified below which the interaction time of the d ...
The mechanical impedance of structures changes with different structural immersion states. It is valuable for industrial application to obtain the rules for the changes to mechanical impedance in advance. Most devices in underwater structures are installed on plates or rafts, so not only the points on the structural surfaces, but also the points on the interior plates need to be taken into the consideration. The structural impedance characteristics in partial immersed states are studied. The dou ...
Boiling experiments were performed with FC-72 on a series of nine in-line simulated microelectronic chips in a flow channel to ascertain the effects of channel orientation on critical heat flux (CHF). The simulated chips, measuring 10 mm x 10 mm, were flush-mounted to one wall of a 20 mm x 5 mm flow channel. The channel was rotated in increments of 45 degrees through 360 degrees such that the chips were subjected to coolant in upflow, downflow, or horizontal flow with the chips on the top or bot ...
When calculating risks from explosions, accurate prediction of the effects of congestion on overpressure has a significant impact. In addition, the protection offered by buildings is also an important factor. The TNO Multi Energy (ME) Method, integrated with source term discharge and dispersion models to assess the extent of flammable clouds, is often used for predicting overpressures (Van Den Berg, 1985). Developed as a more accurate alternative to the TNT-equivalence model, it could initially ...
S U M M A R Y We present a spherical wavelet-based multiscale approach for estimating a spatial velocity field on the sphere from a set of irregularly spaced geodetic displacement observations. Because the adopted spherical wavelets are analytically differentiable, spatial gradient tensor quantities such as dilatation rate, strain rate and rotation rate can be directly computed using the same coefficients. In a series of synthetic and real examples, we illustrate the benefit of the multiscale ap ...
Acoustic resonances in Francis turbines often define undesirable limitations to their operating ranges at high load. The knowledge of the mechanisms governing the onset and the sustenance of these instabilities in the swirling flow leaving the runner is essential for the development of a reliable hydroacoustic model for the prediction of system stability. The present work seeks to study experimentally the unstable draft tube flow by conducting a series of measurements on a reduced Francis Turbin ...
One of the distinctive features of mode-converted waves is their asymmetric moveout i.e., the PS-wave traveltime in general is different if the source and receiver are interchanged caused by lateral heterogeneity or elastic anisotropy. If the medium is anisotropic, the PS-wave moveout asymmetry contains valuable information for parameter estimation that cannot be obtained from pure reflection modes. Here, we generalize the so-called PP + PS = SS method, which is designed to replace reflected PS ...
Semi-autonomous driving assistance systems have a high potential to improve the safety and efficiency of the battery electric vehicles that are enduring limited cruising range. This paper presents an ecologically advanced driver assistance system to extend the functionality of the adaptive cruise control system. A real-time stochastic non-linear model predictive controller with probabilistic constraints is presented to compute on-line the safe and energy-efficient cruising velocity profile. The ...
  • M. Zakaria,
  • Applied Mathematics and Computation
  • 2004
The influence of unsteady boundary layer magnetohydrodynamic flow with thermal relaxation of perfectly conducting fluid, past a semi-infinite plate, is considered. The governing nonlinear partial differential equations are solved using the method of successive approximations. This method is used to obtain the solution for the unsteady boundary layer magnetohydrodynamic flow in the special form when the free stream velocity exponentially depends on time. The effects of Alfven velocity a on the ve ...