197,268 research outputs found
Applications of generalized Ky Fan's matching theorem in minimax and variational inequality
No full textWe present some application of the generalized Ky Fan's Matching Theorem stated by Chebbi, Gourdel and Hammami in minimax and variational inequalities using a generalized coercivity type condition for correspondences defined in L-space.L-structures, L-spaces, L-KKM correspondences, L-coercing family, minimax and variational inequalities.
Combining Text and Image Analysis in the Web Filtering System "WebGuard"
No full text@inproceedings{CI-CHAHIR-2003-2, author = {Hammami, M. and Chahir, Y. and Chen, L.}, title = {Combining Text and Image Analysis in the Web Filtering System "WebGuard"}, booktitle = {IADIS International Conference WWW/Internet 2003}, pages = {611-618}, year = {2003}, address = {Algarve, Portugal}, month = {November} }International audience
Badania mikroskopowe chondrytów Gold Basin i El Hammami
No full textElemental and mineral composition of Gold Basin and El Hammami meteorites discovered in 1995 and 1997 have been studied by analytical electron microscopy and optical microscopy. It was established that the main meteorite minerals: olivines, pyroxenes, kamacite and taenite as well as troilite identified in the samples represent extraterrestrial minerals typical of the ordinary chondrites. Feldspars represented by plagioclase, orthoclase, magnetite, calcite, chromite and silica have been also present in the studied samples. Chemical and mineral composition, iron content, petrologic types of chondrules, their abundance and sizes, the presence of troilite veins and abundance of nonoxidised iron phases confirm H class of El Hammami chondrite, i.e.. olvine-bronzite class, and L class of Gold Basin, i.e. olivine-hyperstene class.Badano skład chemiczny i mineralny meteorytów Gold Basin i El Hammami. Zanalizowano chondry i ciasto skalne. Obecność chondr oliwinowych, chondr piroksenowych, żył troilitowych oraz faz żelazo-niklowych: kamacytu i troilitu świadczą o pozaziemskim pochodzeniu badanych skał. Oprócz minerałów najbardziej rozpowszechnionych w meteorytach takich jak: oliwin, piroksen, kamacyt, taenit i troilit wykryto także plagiklazy, magnetyt, kalcyt, chromit, ortoklaz i krzemionkę. Zgodnie z uprzednią klasyfikacją Gold Basin jest chondrytem klasy L o niskiej zawartości żelaza, a El Hammami chondrytem typu H zawierającym dużo żelaza
Input current and voltage ripple analysis in ldn cells for h-bridge multilevel inverters
No full textThis paper deals with the analysis of the input dc-link voltage ripple in multilevel inverter based on H-bridge and level doubling network (LDN). The LDN is basically a half-bridge fed by a floating capacitor, with voltage self-balancing capability, recalling the concept of a flying capacitor configuration. The amplitude of the LDN voltage ripple is analytically determined considering both the low-order and the switching harmonic components. In particular, peak-To-peak distributions of voltage ripples over the fundamental period are analytically determined, making possible the design of dc-link capacitor relying only on the dc-voltage ripple requirements. The case study makes reference to negligible switching ripple in the output current. It well represents either grid connection or passive load having almost sinusoidal currents. Numerical simulations carried out by MATLAB/Simulink and a complete set of experimental verifications are given to confirm the theoretical developments
The contribution of vertical explosive strength to sprint performance in children
No full textPurpose This study aimed to investigate the relationship between the explosive strength ratio, which is the quotient between maximum height achieved after counter-movement jump with arm and maximum height achieved after standing start jump, and the 30-m sprint performance. Method Eighty-four children performed a series of 30-m sprints, Counter-movement jump with arm (arm-CMJ) and Starting Long Jump (SLJ) (with both legs) in randomized block order during the same testing session. Pearson's product moment correlation coefficients (r) were used to determine the relationship between the explosive strength ratio and sprint performance. The coefficients of determination (R2) were used to examine the amount of explained variance between tests. Stepwise multiple regression analysis was used to estimate the best predictor model of sprint performance. Results The correlation coefficient between explosive strength Ratio: arm-CMJ/SLJ, 10, and 30-m sprint time was moderate (r = 0.40 and 0.48 respectively). However, correlation with flying time 10 < 30-m sprint time (r = 0.52) was large. The Ratio: arm-CMJ/SLJ was the best single predictor factor (p < 0.001) of the flying time 10 < 30-m sprint time, and explained 27 % of the variance. Conclusion For improving sprint performance as well as maximal speed and flying time, coaches could ensure the explosive strength ratio as an index to calibrate sprint development program and also for enhancing sport speed in children. They will be able to use this finding to better test and monitor children's athletes requiring different skills and to evaluate the effects of speed training in children. ?????? 2014 Springer-Verlag Italia
Dc-link current and voltage ripple harmonics in three-phase three-level flying capacitor inverters with sinusoidal carrier-based PWM
No full textThis paper concerns with the analysis and calculation of the low-frequency DC-link input current and voltage ripple harmonic components in three-phase three-level flying capacitor inverter topologies. As a first simplified approach, reference is made to sinusoidal carrier-based PWM, and sinusoidal load currents with unity power factor, well representing most of the grid-connected applications. The proposed method can be straight-forwardly extended to centered PWM with any output power factor angle. Based on the ripple requirements of DC-link voltage, an original simple and effective equation for designing the DC-link capacitor has been proposed, since design guidelines only for the flying capacitors are reported in literature. Numerical simulations have been carried out by Matlab/Simulnik in order to verify the proposed developments
RCC-MPPT algorithms for single-phase PV systems in case of multiple dc harmonics
No full textIn this paper the implementation of maximum power point tracking (MPPT) schemes by the ripple correlation control (RCC) algorithm is discussed in case of multiple ripple harmonics. As an example, a single-phase single-stage grid-connected photovoltaic (PV) system based on H-bridge inverter and level doubling network (LDN) is considered, leading to a multilevel inverter having the double of output voltage levels compared to the basic H-bridge inverter topology. The LDN is basically a half-bridge fed by a floating capacitor, with voltage self-balancing capability. In this case, additional voltage and current harmonics are introduced in the dc-bus of the H-bridge, leading to multiple PV voltage and current low-order harmonics comparing to the double fundamental frequency component in case of basic H-bridge configuration. Voltage and current harmonic components are used in RCC schemes to estimate dP/dV and to drive the PV operating point to the MPP. Different possible dP/dV estimations have been proposed in case of multiple harmonics, and a specific case with LDN has been considered. The steady-state and transient performances of the proposed RCC-MPPT schemes have been numerically tested and compared by MATLAB/Simulink
Evaluation of DC voltage ripple in three-phase PWM voltage source inverters
No full textDetermination of dc-link voltage switching ripple in three-phase PWM voltage source inverters (VSI) is important for the selection and design of the dc-link capacitor. In this paper the complete analysis of the dc-link voltage ripple is given for three-phase PWM VSIs, in case of dc source impedance and balanced load. The dc voltage ripple amplitude is analytically determined as a function of amplitude and phase angle of output current, and modulation index. In particular, peak-to-peak distribution and maximum amplitude over the fundamental period of the dc voltage switching ripple are obtained. Guidelines for designing the dc-link capacitor are given on the basis of the dc-voltage ripple requirements. Simulations results carried out by Matlab/Simulink are provided to verify the analytical developments
Combining Text and Image Analysis in The Web Filtering System "WEBGUARD"
No full text@inproceedings{CI-CHAHIR-2004, author = {Hammami, M. and Chahir, Y. and Chen, L.}, title = {Combining Text And Image Analysis in The Web Filtering System "WEBGUARD"}, booktitle = {Sixth International Conference on Information Integration and Web Based Applications \& Services (iiWAS'04)}, pages = {685-695}, year = {2004}, address = {Jakarta, Indonesia}, month = {September} }International audienceWeb applications increasingly utilize search techniques that heavily rely on content-based text and image analyses. For example, for parental site filtering, it is necessary to identify adult sites. These applications must rely on a semantic analysis of images in the process of identification where text analysis alone is insufficient. In this article, we describe our site filtering system "WebGuard" and show the importance of image analysis in such system. Our results show that it can detect and filter adult content effectively
Evaluation of DC voltage ripple in single-phase H-bridge PWM inverters
No full textIn this paper the complete analysis of the dc-link voltage ripple is given for single-phase H-bridge PWM inverters. The dc voltage ripple amplitude is analytically determined as a function of the modulation index and the load phase angle, considering both the switching frequency component and the double fundamental frequency component (i.e. 100 Hz). Peak-to-peak distribution, maximum amplitude, and rms values of the voltage switching ripple over the fundamental period are analytically determined and numerically verified by numerical simulations carried out by Matlab/Simulink. Simple and effective guidelines to design the dc-link capacitor are given on the basis of the dc-voltage ripple requirements
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