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1.
Micheli E.D. Torre V. Uras S. 《IEEE transactions on pattern analysis and machine intelligence》1993,15(5):434-447
The accuracy and the dependence on parameters of a general scheme for the analysis of time-varying image sequences are discussed. The approach is able to produce vector fields from which it is possible to recover 3-D motion parameters such as time-to-collision and angular velocity. The numerical stability of the computed optical flow and the dependence of the recovery of 3-D motion parameters on spatial and temporal filtering is investigated. By considering optical flows computed on subsampled images or along single scanlines, it is also possible to recover 3-D motion parameters from reduced optical flows. An adequate estimate of time-to-collision can be obtained from sequences of images with spatial resolution reduced to 128×128 pixels or from sequences of single scanlines passing near the focus of expansion. The use of Kalman filtering increases the accuracy and the robustness of the estimation of motion parameters. The proposed approach seems to be able to provide not only a theoretical background but also practical tools that are adequate for the analysis of time-varying image sequences 相似文献
2.
Overview and applications of the reproducing Kernel Particle methods 总被引:11,自引:1,他引:10
W. K. Liu Y. Chen S. Jun J. S. Chen T. Belytschko C. Pan R. A. Uras C. T. Chang 《Archives of Computational Methods in Engineering》1996,3(1):3-80
Summary Multiple-scale Kernel Particle methods are proposed as an alternative and/or enhancement to commonly used numerical methods
such as finite element methods. The elimination of a mesh, combined with the properties of window functions, makes a particle
method suitable for problems with large deformations, high gradients, and high modal density. The Reproducing Kernel Particle
Method (RKPM) utilizes the fundamental notions of the convolution theorem, multiresolution analysis and window functions.
The construction of a correction function to scaling functions, wavelets and Smooth Particle Hydrodynamics (SPH) is proposed.
Completeness conditions, reproducing conditions and interpolant estimates are also derived. The current application areas
of RKPM include structural acoustics, elastic-plastic deformation, computational fluid dynamics and hyperelasticity. The effectiveness
of RKPM is extended through a new particle integration method. The Kronecker delta properties of finite element shape functions
are incorporated into RKPM to develop a C
m
kernel particle finite element method. Multiresolution and hp-like adaptivity are illustrated via examples. 相似文献
3.
Mirey Bonfil Ahmet Sirkecioglu Ozlem Bingol‐Ozakpinar Fikriye Uras F. Seniha Güner 《应用聚合物科学杂志》2014,131(15)
A series of polyurethane film were prepared from poly(ethylene glycol) with different molecular weight (PEG 1500, 3000, and 8000) and castor oil by one‐shot bulk polymerization method. Hexamethylene diisocyanate and 1,4‐buthane diol were used as diisocyanate and chain extender, respectively. In order to characterize the samples, their density, swelling ratio, water contact angle, surface free energy, gel content, thermal, and viscoelastic properties were determined. The effect of the soft segment length (SSL) and hard segment content (HSC) of all polyurethane films on their shape memory behavior such as shape fixity (Rf) and shape recovery (Rr) rates were investigated by bending test. Direct contact and MTT tests were used for assessment of cell adhesion and proliferation. The relatively high Rf and Rr values were obtained for the samples programmed at high temperature difference. Rf increased with decreasing HSC. On the other hand, Rr tended to decrease with increasing SSL. After evaluating experimental data by a nonlinear equation, it was found that HSC is more effective parameter on shape memory property than SSL. The gel content, swelling ratio, and water contact angle of the samples were dependent on both SSL and HSC in their structures. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40590. 相似文献
4.
Nadezhda Barvitenko Muhammad Aslam Alfons Lawen Carlota Saldanha Elisaveta Skverchinskaya Giuseppe Uras Alessia Manca Antonella Pantaleo 《International journal of molecular sciences》2021,22(15)
Changes in plasma membrane curvature and intracellular ionic strength are two key features of cell volume perturbations. In this hypothesis we present a model of the responsible molecular apparatus which is assembled of two molecular motors [non-muscle myosin II (NMMII) and protrusive actin polymerization], a spring [a complex between the plasma membrane (PM) and the submembrane actin-based cytoskeleton (smACSK) which behaves like a viscoelastic solid] and the associated signaling proteins. We hypothesize that this apparatus senses changes in both the plasma membrane curvature and the ionic strength and in turn activates signaling pathways responsible for regulatory volume increase (RVI) and regulatory volume decrease (RVD). During cell volume changes hydrostatic pressure (HP) changes drive alterations in the cell membrane curvature. HP difference has opposite directions in swelling versus shrinkage, thus allowing distinction between them. By analogy with actomyosin contractility that appears to sense stiffness of the extracellular matrix we propose that NMMII and actin polymerization can actively probe the transmembrane gradient in HP. Furthermore, NMMII and protein-protein interactions in the actin cortex are sensitive to ionic strength. Emerging data on direct binding to and regulating activities of transmembrane mechanosensors by NMMII and actin cortex provide routes for signal transduction from transmembrane mechanosensors to cell volume regulatory mechanisms. 相似文献
5.
The membrane forces induced by horizontal ground motion are derived to be used in the coupled Hill's equations for a complete dynamic stability analysis. Excellent agreement between theoretical and available experimental results is obtained. A majority of buckling modes can be correctly identified by considering a geometrical imperfection. The influence of the imperfection on the dynamic buckling characteristics is also discussed. 相似文献
6.
J. Paul Devlin Nevin Uras Mohammed Rahman Victoria Buch 《Israel journal of chemistry》1999,39(3-4):261-272
The relationship between the degree of ionization and the environment of a strong acid is of basic scientific interest. Often this relationship reduces to the interdependence of ion/acid hydration and proton transfer. Despite the presence of pure water, the surface of crystalline ice, particularly at cryogenic temperatures, is one of limited (controlled?) availability of water of hydration. Here, the detailed nature of the ice surface and the states of strong acids adsorbed to ice at cryogenic temperatures are examined. These subjects are of special current interest since the ability to model the complex chemistry that occurs on the surfaces of water-rich particles in the atmosphere, particularly in the stratosphere over the polar regions, requires a valid concept of the acid-ice interface. Our combined spectroscopic and simulation studies have identified the surface of free-standing ice particles as badly disordered, with a range of water-ring sizes and an increased level of H-bond saturation relative to an ordered ice surface. FT-IR results are reported for the interaction of the surface of such ice particles with submonolayer amounts of adsorbed DCl, DBr, and HNO3 and for multilayer exposure to DCl. The DCl and DBr adsorbed states demonstrate behavior familiar from observations on strongly bound molecular adsorbates. Two methods have been devised for exposure of the nanocrystals to HNO3 One gives an ionic state initially, while the initial state of the other approach is molecular. In both instances, the system is observed to evolve, with time/warming, towards a common mixed molecular–ionic adsorbed state. 相似文献
7.
Abdelrahman K. A. A. Salama Marija V. Trkulja Emilio Casanova Iris Z. Uras 《International journal of molecular sciences》2022,23(23)
The field of targeted protein degradation (TPD) is a rapidly developing therapeutic modality with the promise to tame disease-relevant proteins in ways that are difficult or impossible to tackle with other strategies. While we move into the third decade of TPD, multiple degrader drugs have entered the stage of the clinic and many more are expected to follow. In this review, we provide an update on the most recent advances in the field of targeted degradation with insights into possible clinical implications for cancer prevention and treatment. 相似文献
8.
Kent T. Danielson Su Hao Wing Kam Liu R. Aziz Uras Shoafan Li 《International journal for numerical methods in engineering》2000,47(7):1323-1341
A parallel computational implementation of modern meshless methods is presented for explicit dynamic analysis. The procedures are demonstrated by application of the Reproducing Kernel Particle Method (RKPM). Aspects of a coarse grain parallel paradigm are detailed for a Lagrangian formulation using model partitioning. Integration points are uniquely defined on separate processors and particle definitions are duplicated, as necessary, so that all support particles for each point are defined locally on the corresponding processor. Several partitioning schemes are considered and a reduced graph-based procedure is presented. Partitioning issues are discussed and procedures to accommodate essential boundary conditions in parallel are presented. Explicit MPI message passing statements are used for all communications among partitions on different processors. The effectiveness of the procedure is demonstrated by highly deformable inelastic example problems. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
9.
Giuseppe Uras Xinuo Li Alessia Manca Antonella Pantaleo Marco Bo Jinyi Xu Stephanie Allen Zheying Zhu 《International journal of molecular sciences》2022,23(23)
Alzheimer’s disease (AD) is characterized by an initial accumulation of amyloid plaques and neurofibrillary tangles, along with the depletion of cholinergic markers. The currently available therapies for AD do not present any disease-modifying effects, with the available in vitro platforms to study either AD drug candidates or basic biology not fully recapitulating the main features of the disease or being extremely costly, such as iPSC-derived neurons. In the present work, we developed and validated a novel cell-based AD model featuring Tau hyperphosphorylation and degenerative neuronal morphology. Using the model, we evaluated the efficacy of three different groups of newly synthesized acetylcholinesterase (AChE) inhibitors, along with a new dual acetylcholinesterase/glycogen synthase kinase 3 inhibitor, as potential AD treatment on differentiated SH-SY5Y cells treated with glyceraldehyde to induce Tau hyperphosphorylation, and subsequently neurite degeneration and cell death. Testing of such compounds on the newly developed model revealed an overall improvement of the induced defects by inhibition of AChE alone, showing a reduction of S396 aberrant phosphorylation along with a moderate amelioration of the neuron-like morphology. Finally, simultaneous AChE/GSK3 inhibition further enhanced the limited effects observed by AChE inhibition alone, resulting in an improvement of all the key parameters, such as cell viability, morphology, and Tau abnormal phosphorylation. 相似文献
10.
In this paper, the governing equations which consider dynamic fluid-structure interaction, modal coupling in both axial and circumferential directions, and dynamic buckling are derived. The various pressure components acting on the shell wall due to a seismic event are also analyzed. The matrix equation of motion for liquid-filled shells is obtained through a Galerkin/Finite Element discretization procedure. The modal coupling among the various combinations of axial and circumferential modes are identified with a particular reference to the fluid-structure system under seismic excitation. Finally, the equations for the dynamic stability analysis of liquid-filled shells are presented. 相似文献