853 research outputs found

    HILLE-KNESER-TYPE CRITERIA FOR SECOND-ORDER DYNAMIC EQUATIONS ON TIME SCALES

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    We consider the pair of second-order dynamic equations, (r(t)(xΔ)γ)Δ + p(t)xγ(t) = 0 and (r(t)(xΔ)γ)Δ + p(t)xγσ (t) = 0, on a time scale T, where γ \u3e 0 is a quotient of odd positive integers. We establish some necessary and sufficient conditions for nonoscillation of Hille-Kneser type. Our results in the special case when T = R involve the well known Hille-Kneser-type criteria of second-order linear differential equations established by Hille. For the case of the second-order half-linear differential equation, our results extend and improve some earlier results of Li and Yeh and are related to some work of Dosly and Rehak and some results of Rehak for half-linear equations on time scales. Several examples are considered to illustrate the main results

    Optimization and Analysis of Underactuated Linkage Robotic Finger

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    In this study it is required to maximize the transmission performance, which is leading to increase the transmitted torque from the actuated joints to the underactuated joints through transmission mechanism. Accordingly grasping forces in finger phalanges will increase. Studying the four bar mechanism parameters of a specific configuration within defined limits led to the linkage transmission defect parameter, which play a major role in deciding the linkage performance, used as optimization objective function to be minimized. This study presents an optimization procedure carried out using matlab fminunc function, formulated by using Freudenstein's equations to be applied on a (Cassino-Underactuated-Multifinger-Hand) design , using  one finger and a thumb .A mathematical model of grasping forces of the finger were introduced taking into account the solid links in the( Ca.U.M.Ha)  robotic finger . Keywords: Linkage , underactuated, optimizatio

    Multi-level encryption for 3D mesh model based on 3D Lorenz chaotic map and random number generator

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    The increasing 3D model applications in various areas of life and widespread use like industry leads to 3D models being stolen and attacked by hackers; therefore, 3D model protection is a fundamental matter nowadays. In this paper, the proposed scheme will provide stringent security for the 3D models by implementing multiple levels of security with preserving the original dimensionality of the 3D model using the weight factor (w). The first level of security is achieved by applying a shuffling process for the vertices based on a key from random number generator (RNG), which provides good confusion. The second level is implemented by modifying the vertices values based on 3D keys from 3D Lorenz chaotic map, which provides good diffusion. The proposed scheme was applied on different 3D models varying in the vertices and faces number. The results illustrate that the proposed scheme deforms the entire 3D model based on Hausdorff distance (HD) approximately 100 after the encryption process, making it resist statistical attack. The scheme provides high security against brute force attack because it has a large key space equal to 10,105 and high security against deferential attack through secret key sensitivity using number of pixels change rate (NPCR) near to 99:6% and unified average changing intensity (UACI) near to 33:4%

    Contact mechanics for soft robotic fingers: modeling and experimentation

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    Human fingers possess mechanical characteristics, which enable them to manipulate objects. In robotics, the study of soft fingertip materials for manipulation has been going on for a while; however, almost all previous researches have been carried on hemispherical shapes whereas this study concentrates on the use of hemicylindrical shapes. These shapes were found to be more resistant to elastic deformations for the same materials. The purpose of this work is to generate a modified nonlinear contact-mechanics theory for modeling soft fingertips, which is proposed as a power-law equation. The contact area of a hemicylindrical soft fingertip is proportional to the normal force raised to the power of γcy, which ranges from 0 to 1/2. Subsuming the Timoshenko and Goodier (S. P. Timoshenko and J. N. Goodier, Theory of Elasticity, 3rd ed. (McGraw-Hill, New York, 1970) pp. 414-420) linear contact theory for cylinders confirms the proposed power equation. We applied a weighted least-squares curve fitting to analyze the experimental data for different types of silicone (RTV 23, RTV 1701, and RTV 240). Our experimental results supported the proposed theoretical prediction. Results for human fingers and hemispherical soft fingers were also compare

    Application of SAR time-series and deep learning for estimating landslide occurence time

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    The time series of normalized difference vegetation index (NDVI) and interferometric coherence extracted from optical and Synthetic Aperture Radar (SAR) images, respectively, have strong responses to sudden landslide failures in vegetated regions, which is expressed by a sudden increase or decrease in the values of NDVI and coherence. Compared with optical sensors, SAR sensors are not affected by cloud and daylight conditions and can detect the occurrence time of failure in near real-time. The purpose of this paper is to automatically determine the time of failure occurrence using time series coherence values. We propose, based on some existing anomaly detection algorithms, a deep neural network-based anomaly detection strategy that combines supervised and unsupervised learning without a priori knowledge about failure time. Our experiment using July 21, 2020 Shaziba landslide in China shows that in comparison to widely used unsupervised methodology, the use of our algorithm leads to a more accurate detection of the timing of the landslide failure

    Upcycling Used Garments to Recreate Sustainable Fashion Designs Treated by Soil Release Finishing

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    Upcycled garments can have that independent appeal. No matter whom the designer is or what styling options designers choose, these upcycled fashion garments and accessories are by nature one-of-a kind. Finishing of textile fabric is carried out to increase attractiveness and/or serviceability of the fabric. Different finishing treatments are available to get various effects, which add value to the basic textile material, which can be better solutions for sustainable fashion. The sustainable fashion was achieved to a certain extent by using available materials to its ultimate USAge, using waste material, recycling of the products, planning second life for the fashion product, slowing down the fashion etc. The main idea to do so is to develop more sustainable and responsible designs. This paper is not just about recycled clothes but about fashion, recycling, upcycling, adding value and uniqueness by the resulting one-of-a-kind design available for women to purchase in any retail store. Create nine designs using waste garments treated by soil release finishing agent as a source of sustainable fashionable designs

    Longtime behavior of nonlocal Cahn-Hilliard equations

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    Here we consider the nonlocal Cahn-Hilliard equation with constant mobility in a bounded domain. We prove that the associated dynamical system has an exponential attractor, provided that the potential is regular. In order to do that a crucial step is showing the eventual boundedness of the order parameter uniformly with respect to the initial datum. This is obtained through an Alikakos-Moser type argument. We establish a similar result for the viscous nonlocal Cahn-Hilliard equation with singular (e.g., logarithmic) potential. In this case the validity of the so-called separation property is crucial. We also discuss the convergence of a solution to a single stationary state. The separation property in the nonviscous case is known to hold when the mobility degenerates at the pure phases in a proper way and the potential is of logarithmic type. Thus, the existence of an exponential attractor can be proven in this case as well
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