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991.
Optical flow estimation is a recurrent problem in several disciplines and assumes a primary importance in a number of applicative
fields such as medical imaging [12], computer vision [6], productive process control [4], etc. In this paper, a differential
method for optical flow evaluation is being presented. It employs a new error formulation that ensures a more than satisfactory
image reconstruction in those points which are free of motion discontinuity. A dynamic scheme of brightness-sample processing
has been used to regularise the motion field. A technique based on the concurrent processing of sequences with multiple pairs
of images has also been developed for improving detection and resolution of mobile objects on the scene, if they exist. This
approach permits to detect motions ranging from a fraction of a pixel to a few pixels per frame. Good results, even on noisy
sequences and without the need of a filtering pre-processing stage, can be achieved. The intrinsic method structure can be
exploited for favourable implementation on multi-processor systems with a scalable degree of parallelism. Several sequences,
some with noise and presenting various types of motions, have been used for evaluating the performances and the effectiveness
of the method.
Carmelo Lodato received his Dr. Ing. Degree in Civil Engineering from the University of Palermo, Italy, in 1987. He is Researcher at the
High Performance Computing and Networking Institute (ICAR) of the Italian National Research Council (CNR). His current research
interests include computer vision, image processing, motion analysis, optimization and stochastic algorithms.
Salvatore Lopes received his Dr. Ing. Degree (summa com laude) in Nuclear Engineering from the University of Palermo, Italy, in 1988. He
is Researcher at the High Performance Computing and Networking Institute (ICAR) of the Italian National Research Council (CNR).
His current research interests include computer vision, image processing, motion analysis, optimization and stochastic algorithms. 相似文献
992.
I. Fenoglio G. Martra L. Prandi M. Tomatis S. Coluccia B. Fubini 《Journal of Materials Synthesis and Processing》2000,8(3-4):145-153
The release of free radicals from mechanically ground mineral dusts in aqueous suspensions has been employed to predict the possible pathogenic potential of the dusts when inhaled. Two separate free radical-generating reactions have been considered: formation of the OH radical from hydrogen peroxide via a "Fentonlike" reaction and of a carbon centered radical, following cleavage of a carbon–hydrogen bond. The particulate examined were: variously contaminated quartz dusts, whose well-documented pathogenicity varies from one to the other source; iron- and titanium-doped alumina pigments, prepared via a mechanochemical reaction, whose pathogenic potential is unknown, and hard metal mixtures, obtained from tungsten carbide (WC) and one metal dust, namely Fe, Co, or Ni, the cobalt mixture only being a renown hazardous material. Quartz obtained by grinding coarse particles in grinding chambers composed of steel, widia, corundum, and agate, retain some characteristics of the wall chamber material, which deeply affects its capability to generate radicals and may explain the variability of quartz hazard. Insertion of ions in the mechanochemically prepared pigments imparts to the particle suspected free radical-generating properties. Among the hard metal mixtures examined, the most active is the cobalt one. 相似文献
993.
Baotong Hu Yiwang Bao Xiaojia Su Detian Wan Qingguo Feng Salvatore Grasso Chunfeng Hu 《International Journal of Applied Ceramic Technology》2021,18(5):1863-1871
In this work, ultrafast thermal shock of Ti3AlC2 ceramic was evaluated in water and air by utilizing the induction heating method. First, the annealed samples were heated to the set temperature in tens of seconds and dropped into the cooling water within 0.1 s which is rather short not to degrade the sample temperature. Compared to the traditional thermal shock method when quenching in water, the abnormal thermal shock phenomenon did not occur, which is owing to that no dense oxide layers were formed on the samples’ surface to act as the thermal barrier. The continuous decrease in residual flexural strength when quenched in water is associated with water infiltration, chemical reaction, and large surface tensile stress. The residual strength has 27.25 MPa upon 1250°C. Second, at the same testing temperature, the residual flexural strength when quenched in air maintains a high value of 388 MPa up to 1400°C. Dense oxide scales existed on the quenched surface of Ti3AlC2 samples. The results exhibit that Ti3AlC2 ceramic possesses excellent thermal shock resistance in water and air, suitable to be applied in extreme environments. 相似文献
994.
Calosso CE Micalizio S Godone A Bertacco EK Levi F 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2007,54(9):1731-1740
Pulsing the different operation phases of a vapor-cell clock (optical pumping, interrogation, and detection) has been recognized as one of the most effective techniques to reduce light shift and then to improve the stability perspectives of vapor cell clocks. However, in order to take full advantage of the pulsed scheme, a fast-gated electronics is required, the times involved being of the order of milliseconds. In this paper we describe the design and the implementation of the electronics that synchronizes the different phases of the clock operation, as well as of the electronics that is mainly devoted to the thermal stabilization of the clock physics package. We also report some characterization measurements, including a measurement of the clock frequency stability. In particular, in terms of Allan deviation, we measured a frequency stability of 1.2 x 10(-12) tao(-1/2) for averaging times up to tao = 10(5) s, a very interesting result by itself and also for a possible space application of such a clock. 相似文献
995.
On the basis of an experimentally validated simple theoretical model, it is demonstrated unambiguously that when an unbiased conductor is probed by a scanning electrochemical tip (scanning electrochemical microscopy, SECM), it performs as a bipolar electrode. Though already envisioned in most recent SECM theories, this phenomenon is generally overlooked in SECM experimental investigations. However, as is shown here, this may alter significantly positive feedback measurements when the probed conductor is not much larger than the tip. 相似文献
996.
Guillem Hernández-Sola Jordi Perelló Fernando Agraz Luis Velasco Salvatore Spadaro Gabriel Junyent 《Photonic Network Communications》2011,21(2):141-151
The ability of computing optimal routes poses new challenges when extending it to larger multi-domain network scenarios, as
the quality of these computed end-to-end inter-domain routes depends on the selection of the domain sequence to be traversed.
In the scope of the Internet Engineering Task Force (IETF), the Path Computation Element (PCE) Working Group has not provided
definitive solutions to address the domain sequence selection problem, being still a work in progress. To this goal, the Path
Computation Flooding (PCF) approach appears as a possible extension to Backward Recursive PCE-based Computation (BRPC) to
calculate optimal end-to-end inter-domain paths without requiring a pre-configured domain sequence. Nonetheless, PCF presents
major scalability issues in terms of network control overhead and path computation complexity, thus pleading for more accurate
domain sequence selection techniques. This paper describes two novel mechanisms to establish inter-domain paths calculating
the sequence of domains to be crossed when it is not known in advance. Both procedures make a good trade-off between the control
overhead introduced and the accuracy of the computed end-to-end route. The obtained simulation results show the benefits of
the proposed contributions, drastically reducing the control overhead while keeping the connection blocking probability close
to the optimal values. 相似文献
997.
Antonina Pirrotta Stefano Cutrona Salvatore Di Lorenzo Alberto Di Matteo 《International journal for numerical methods in engineering》2015,104(9):869-886
This paper deals with the response determination of a visco‐elastic Timoshenko beam under static loading condition and taking into account fractional calculus. In particular, the fractional derivative terms arise from representing constitutive behavior of the visco‐elastic material. Further, taking advantages of the Mellin transform method recently developed for the solution of fractional differential equation, the problem of fractional Timoshenko beam model is assessed in time domain without invoking the Laplace‐transforms as usual. Further, solution provided by the Mellin transform procedure will be compared with classical Central Difference scheme one, based on the Grunwald–Letnikov approximation of the fractional derivative. Moreover, Timoshenko beam response is generally evaluated by solving a couple of differential equations. In this paper, expressing the equation of the elastic curve just through a single relation, a more general procedure, which allows the determination of the beam response for any load condition and type of constraints, is developed. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
998.
Microfluidics: A Versatile and Robust Microfluidic Platform Toward High Throughput Synthesis of Homogeneous Nanoparticles with Tunable Properties (Adv. Mater. 14/2015) 下载免费PDF全文
999.
Salvatore Serrano Giuseppe Campobello Alessandro Leonardi Sergio Palazzo Laura Galluccio 《Wireless Communications and Mobile Computing》2016,16(10):1192-1208
Support of Voice over Internet Protocol (VoIP) services in wireless mesh networks requires implementation of efficient policies to support low‐delay data delivery. Multipath routing is typically supported in wireless mesh networks at the network level to provide high fault tolerance and load balancing because links in the proximity of the wireless mesh gateways can be very stressed and overloaded, thus causing scarce performance. As a consequence of using multipath solutions, lower delay and higher throughput can be supported also when a given path is broken because of mobility or bad channel conditions, and alternative routes are available. This can be a relevant improvement especially when assuming that real‐time traffic, such as VoIP, travels into the network. In this paper, we address the problem of Quality of Service (QoS) support in wireless mesh networks and propose a multipath routing strategy that exploits the Mean Opinion Score (MOS) metric to select the most suitable paths for supporting VoIP applications and performing adaptive load balancing among the available paths to equalize network traffic. Performance results assess the effectiveness of the proposed approach when compared with other existing methodologies. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
1000.
The Clash of Mechanical and Electrical Size‐Effects in ZnO Nanowires and a Double Power Law Approach to Elastic Strain Engineering of Piezoelectric and Piezotronic Devices 下载免费PDF全文