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排序方式: 共有220条查询结果,搜索用时 15 毫秒
1.
Matteo Palpacelli Giacomo Palmieri Luca Carbonari David Corinaldi 《Journal of Intelligent and Robotic Systems》2018,91(2):155-163
This paper is focused on the development and validation of an error kinematic model of a mini spherical robot, aimed at its kinematic calibration. The robot is actually a spatial five-bar linkage, provided with two rotational degrees of freedom. A non-overconstrained kinematics is assumed for the robot in order to provide a simple mathematical model and allow a sensitivity analysis of all the involved geometric parameters. A simplified version of the model is proposed. It differs only for the degree of approximation. A comparison between full and reduced models is presented by means of numerical simulations, analyzing their behavior in a significant region of the robot workspace. In order to validate both of them a robot calibration is carried out on a physical prototype of the robot using a vision system, namely a fixed camera in a eye-to-hand configuration. An iterative algorithm aimed at the experimental identification of the geometric data of the robot is used. Some experimental results show the effectiveness of the study. 相似文献
2.
Francesco Palmieri Ugo Fiore Aniello Castiglione Alfredo De Santis 《Applied Soft Computing》2013,13(1):615-627
In the last years, the interest in methods and techniques for circumventing the security of the available digital video broadcasting systems is continuously increasing. Digital TV providers are struggling to restrict access to their video contents only to authorized users, by deploying more and more sophisticated conditional access systems. At the state-of-the-art, the most significant menace is the card-sharing activity which exploits a known weakness allowing an authorized subscriber to provide access to digital contents to a potentially large group of unauthorized ones connected over a communication network. This is usually realized by using ad hoc customized devices. Detecting the presence of these illegal systems on a network, by recognizing their related traffic is an issue of primary importance. Unfortunately, to avoid the identification of such traffic, payload obfuscation strategies based on encryption are often used, hindering packet inspection techniques.This paper presents a strategy for the detection of card-sharing traffic, empowered by machine-learning-driven traffic classification techniques and based on the natural capability of wavelet analysis to decompose a traffic time series into several component series associated with particular time and frequency scales and hence allowing its observation at different frequency component levels and with different resolutions. These ideas have been used for the proof-of-concept implementation of an SVM-based binary classification scheme that relies only on time regularities of the traffic and not on the packet contents and hence is immune to payload obfuscation techniques. 相似文献
3.
Bernardeschi Cinzia Dini Gianluca Palmieri Maurizio Racciatti Francesco 《Journal in Computer Virology》2021,17(3):249-263
Journal of Computer Virology and Hacking Techniques - When designing Wireless Sensor Networks it is important to analyze their security risks and provide adequate solutions for protecting them from... 相似文献
4.
MG Palmieri C Iani A Scalise MT Desiato M Loberti S Telera MD Caramia 《Canadian Metallurgical Quarterly》1999,815(2):192-199
In the present study, the effects of benzodiazepines (diazepam) were evaluated in terms of cortical excitability changes, as tested with transcranial magnetic simulation (TMS). In particular, analyzed were drug-induced changes regarding two selected parameters of TMS: (1) the cortical excitability threshold and (2) the silent period duration (SP). For this purpose, we evaluated the effects of long-term therapy with diazepam in the patients affected by anxiety disorders and the changes induced by single oral doses of diazepam in both healthy controls and patients. In addition, we tested cortical excitability changes in two 'extreme conditions' where a considerable concentration of serum benzodiazepine-like activity was reached, as represented by diazepam overdose and idiopathic recurrent stupor (IRS). In both groups of patients, a significant increment of motor threshold was found, while in the overdose patients, the SP was also increased. The administration of flumazenil in these two conditions was followed by a prompt reversal effect, consisting of a return to normal cortical excitability parameters. The long-term usage of diazepam in patients with anxiety disorders is associated with significantly increased threshold; the increased value of these parameters was temporarily further enhanced by the administration of a single oral dose of diazepam, which, in normal control subjects, is not associated with changes of cortical excitability. The results of this study reveal that different physio-pathological conditions induced by the influence of benzodiazepine and its antagonist are reflected in excitability changes which attest to the involvement and modification of cortical GABAergic activity. 相似文献
5.
Appropriate knowledge of viscoelastic properties of polymers and elastomers is of fundamental importance for a correct modelization
and analysis of structures where such materials are present, especially when dealing with dynamic and vibration problems.
In this paper experimental results of a series of compression and tension tests on specimens of styrene-butadiene rubber and
polypropylene plastic are presented; tests consist of creep and relaxation tests, as well as cyclic loading at different frequencies.
Experimental data are then used to calibrate some linear viscoelastic models; besides the classical approach based on a combination
in series or parallel of standard mechanical elements as springs and dashpots, particular emphasis is given to the application
of models whose constitutive equations are based on differential equations of fractional order (Fractional Derivative Model).
The two approaches are compared analyzing their capability to reproduce all the experimental data for given materials; also,
the main computational issues related with these models are addressed, and the advantage of using a limited number of parameters
is demonstrated. 相似文献
6.
Roberto Cigliutti Andrea Galtarossa Massimo Giltrelli Daniele Grosso Andrew W.R. Leitch Luca Palmieri Stefano Santoni Luca Schenato David Waswa 《Optical Fiber Technology》2009,15(3):242-250
Polarization Mode Dispersion (PMD) compensation has been a matter of investigation of several papers in literature. The proposed solutions belong basically to two large families: electronic compensators and optical compensators. Both PMD compensator schemes have advantages and disadvantages: electronic PMD compensators are usually simple to include in line-terminal, potentially low-cost, very fast, and FEC compatible but their development is strongly dependent on IC technology capability that at this time allows device developments up to the 10 Gbit/s bit rates area. Furthermore, they are strongly dependent on modulation formats, and they can operate only on a single channel. Conversely, optical compensators are independent of bit rate and modulation format and potentially they can compensate more channels simultaneously; their major drawbacks are the longer response time and the complexity in the feedback signal process within the control algorithm. In this paper we consider an optical Polarization Mode Dispersion Compensator (PMDC) that is simple to realize and easy to include at limited costs in each EDFA module (distributed compensation) as well as a single-stage front-end compensator. Numerical analysis of the PMDC and experimental results confirm the utility of the PMDC proposed and its capability in compensating DGD larger than 20 ps in NRZ and RZ 40 Gbit/s optical systems. 相似文献
7.
Paige A. Palmieri Richard W. Hartel 《Journal of the American Oil Chemists' Society》2019,96(8):911-926
Cocoa powder quality is determined by its color, flavor, dispersion, and flow properties, which can be controlled via tempering. Design of a cocoa powder tempering profile, however, requires that the mechanism of cocoa butter crystallization in cocoa powder be fully understood. Low-fat (8–12%) and high-fat (20–24%) cocoas were sourced from two commercial manufacturers at varying degrees of alkalization and compared with two commercial cocoa butters. Unrefined paired cocoa powders and cocoa butters sampled from the hydraulic press were also evaluated. Isothermal crystallization kinetics and polymorphism of cocoa powders and cocoa butters were compared at 18, 21, and 24 °C using a direct time-domain nuclear magnetic resonance method, differential scanning calorimetry, and x-ray diffraction. Crystallization was also studied under dynamic tumbling conditions. It was found that cocoa butter in cocoa powder was nucleated by the cocoa powder matrix and transitioned to higher-stability polymorphs more rapidly than bulk cocoa butters. High-fat cocoas also exhibited enhanced crystallization kinetics relative to low-fat cocoas, showing that differences in the cocoa microstructure may influence crystallization behavior. Notably, alkalization did not significantly affect the crystallization behavior of most cocoa powders. Finally, it was found that tumbling conditions led to crystallization of βV and that caking, especially of high-fat cocoas, could be reduced by a static low-temperature hold step prior to tumbling. Overall, these results demonstrated that crystallization of cocoa butter in cocoa powder is influenced both by the intrinsic attributes of the cocoa powder as well as the conditions of the tempering process. 相似文献
8.
Filippo Terrasi Nicola De Cesare Antonio D’Onofrio Carmine Lubritto Fabio Marzaioli Isabella Passariello Carlo Sabbarese Gianluca Borriello Antonio Palmieri 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2008,266(10):2221-2224
The CIRCE AMS system started operation in March 2005. The measurement of isotopic ratios 14C/12C in samples of archaeological and environmental interest has rapidly attained high precision and accuracy levels in routine operation. The results of the intercomparison campaign in the framework of the VIRI program, as well as the outcome of a statistical analysis of the about 200 control measurements performed with standard samples, have shown the capability of the whole system for high precision measurements (δR/R < 0.3%), allowing systematic investigations in both archaeological and environmental sciences. 26Al AMS has been implemented for the measurement of the astrophysically relevant 25Mg(p,γ)26Al reaction cross section, while a beam line is under construction for the measurement of actinides isotopic ratios. 相似文献
9.
Compton Rebecca J.; Heller Wendy; Banich Marie T.; Palmieri Patrick A.; Miller Gregory A. 《Canadian Metallurgical Quarterly》2000,14(2):254
This investigation examined how hemispheric asymmetry and interhemispheric processing contribute to attentional biases toward emotional information. Participants (n?=?88) named the color of lateralized squares presented concurrently with neutral, positive, or threatening words. A left-hemisphere advantage in color naming was reduced when distractors were emotional, suggesting right-hemisphere priming by emotional stimuli. Furthermore, the advantage of dividing the word and color across visual fields was increased for emotion words when they were frequently presented, indicating a strategic use of interhemispheric division of labor to reduce the distracting effect of emotional words. Finally, participants with high levels of anxious apprehension were most likely to make use of this interhemispheric processing strategy, supporting a processing efficiency theory of cognitive function in anxiety. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
10.
Anthony Palmieri 《Drug development and industrial pharmacy》1986,12(10):1477-1502
This report details the effect of aging on release of aspirin from four PEG blends containing crospovidone as a disintegrant in concentrations of 0, 0.5, 1 and 5%. It has been reported in the literature that release from suppository formulations is often altered upon aging. In this experiment, suppositories containing 350 mg aspirin were dissolved in 1,000 mls of pH 8.0 dissolution fluid, at 37.5° with an agitation rate of 50 rpm. Suppositories were designated as fresh (less than 10 days old), 4 months old and 6 months old. Aspirin was assayed at 265 nm. Dissolution profiles as well as dissolution half-times were reported. Aging had little effect on Base A and Base B. However, Ease C exhibited an ambiguous effect in that the dissolution half-times were inconsistent. Base D exhibited a dramatic change in release upon aging in that the dissolution half-times increased from 23 minutes to 55 minutes with 1/22 crospovidone. It is hypothesized that Base D stabilized when larger amounts of crospovidone are used although the exact mechanism of this stabilization is unknown 相似文献