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Fractional Sliding Mode Control of Underwater ROVs subject to Non-differentiable Disturbances
Aldo-Jonathan Muñoz-Vázquez,Heriberto Ramírez-Rodríguez,Vicente Parra-Vega,Anand Sánchez-Orta 제어·로봇·시스템학회 2017 International Journal of Control, Automation, and Vol.15 No.3
Some hydrodynamic phenomena of an underwater Remotely Operated Vehicle (ROV), such as turbulence,cavitation, and multi-phase fluidic regimes, are associated to continuous but nowhere differentiable functions. These disturbances stand as complex forces potentially influencing the ROVs during typical navigation tasks. In thispaper, the tracking control of a ROV subject to nonsmooth Hölder disturbances is proposed based on a fractionalorderrobust controller that ensures exponential tracking. Notably, the controller gives rise to a closed-loop systemwith the following characteristics: a) continuous control signal that alleviates chattering effects; b) the fractionalsliding motion is substantiated on a proposed resetting memory principle; c) the control is robust to model uncertainties;and d) exact rejection of Hölder disturbances in finite-time. A representative simulation study reveals thefeasibility of the proposed scheme.
Nonlinear regression models based on scale mixtures of skew-normal distributions
Aldo M. Garay,Víctor H. Lachos,Carlos A. Abanto-Valle 한국통계학회 2011 Journal of the Korean Statistical Society Vol.40 No.1
An extension of some standard likelihood based procedures to nonlinear regression models under scale mixtures of skew-normal (SMSN) distributions is developed. This novel class of models provides a useful generalization of the symmetrical nonlinear regression models since the random terms distributions cover both symmetric as well as asymmetric and heavy-tailed distributions such as skew-t, skew-slash, skew-contaminated normal,among others. A simple EM-type algorithm for iteratively computing maximum likelihood estimates is presented and the observed information matrix is derived analytically. In order to examine the robust aspect of this flexible class against outlying and influential observations, some simulation studies have also been presented. Finally, an illustration of the methodology is given considering a data set previously analyzed under normal and skew-normal nonlinear regression models.
Chelating and antibacterial properties of chitosan nanoparticles on dentin
Aldo del Carpio-Perochena,Clovis Monteiro Bramante,Marco Antonio Hungaro Duarte,Marcia Regina de Moura,Fauze Ahmad Aouada,Anil Kishen 대한치과보존학회 2015 Restorative Dentistry & Endodontics Vol.40 No.3
Objectives: The use of chitosan nanoparticles (CNPs) in endodontics is of interest due to their antibiofilm properties. This study was to investigate the ability of bioactive CNPs to remove the smear layer and inhibit bacterial recolonization on dentin. Materials and Methods: One hundred bovine dentin sections were divided into five groups (n = 20 per group) according to the treatment. The irrigating solutions used were 2.5% sodium hypochlorite (NaOCl) for 20 min, 17% ethylenediaminetetraacetic acid (EDTA) for 3 min and 1.29 mg/mL CNPs for 3 min. The samples were irrigated with either distilled water (control), NaOCl, NaOCl-EDTA, NaOCl-EDTA-CNPs or NaOCl-CNPs. After the treatment, half of the samples (n = 50) were used to assess the chelating effect of the solutions using portable scanning electronic microscopy, while the other half (n = 50) were infected intra-orally to examine the post-treatment bacterial biofilm forming capacity. The biovolume and cellular viability of the biofilms were analysed under confocal laser scanning microscopy. The Kappa test was performed for examiner calibration, and the non-parametric Kruskal-Wallis and Dunn tests (p < 0.05) were used for comparisons among the groups. Results: The smear layer was significantly reduced in all of the groups except the control and NaOCl groups (p < 0.05). The CNPstreated samples were able to resist biofilm formation significantly better than other treatment groups (p < 0.05). Conclusions: CNPs could be used as a final irrigant during root canal treatment with the dual benefit of removing the smear layer and inhibiting bacterial recolonization on root dentin.
Aldo Bellon,Isztar Zawadzki,Alamelu Kilambi,Hee Choon Lee,이규원 한국기상학회 2010 Asia-Pacific Journal of Atmospheric Sciences Vol.46 No.3
A Variational Echo Tracking (VET) technique has been applied to four months of archived data from the South Korean radar network in order to examine the influence of the various user-selectable parameters on the skill of the resulting 20-min to 4-h nowcasts. The latter are computed over a (512 × 512) array at 2-km resolution. After correcting the original algorithm to take into account the motion of precipitation across the boundaries of such a smaller radar network,we concluded that the set of default input parameters initially assumed is very close to the optimum combination. Decreasing to (5 × 5) or increasing to (50 × 50) the default vector density of (25 × 25), using two or three maps for velocity determination, varying the relative weights for the constraints of conservation of reflectivity and of the smoothing of the velocity vectors, and finally the application of temporal smoothing all had only marginal effects on the skill of the forecasts. The relatively small sensitivity to significant variations of the VET default parameters is a direct consequence of the fact that the major source of the loss in forecast skill cannot be attributed to errors in the forecast motion, but to the unpredictable nature of the storm growth and decay. Changing the time interval between maps, from 20to 10 minutes, and significantly increasing the reflectivity threshold from 15 to 30 dBZ had a more noticeable reduction on the forecast skill. Comparisons with the Eulerian “zero velocity” forecast and with a "single" vector forecast have also been performed in order to determine the accrued skill of the VET algorithm. Because of the extensive stratiform nature of the precipitation areas affecting the Korean peninsula, the increased skill is not as large as may have been anticipated. This can be explained by the greater extent of the precipitation systems relative to the size of the radar coverage domain
Aldo Izaguirre,Arantza Govela,Ismael Delgado,Carlos Mateos Troncoso,Maria Parra,Enrique Alvarez Viana 대한외과학회 2018 Annals of Surgical Treatment and Research(ASRT) Vol.95 No.1
Purpose: Nosocomial infections account for one of the most serious complications in hospitalized patients around the world. Surgical site infections have significant economic implications, and surgical antisepsis plays an important role in such processes. Methods: With prior approval by the Institutional Review Board and informed consent, 10 volunteers were randomly assigned to 3 protocols on hand antisepsis: protocol A (chloroxylenol 3%), protocol B (benzalkonium chloride at 1%), and protocol C (ethyl alcohol 61%, 1% chlorhexidine gluconate). Smears from both hands were cultured after each hand protocol (t0) and at the end of suturing (t1). Colony forming units were counted (CFUs on blood agar dishes) with digital counting software (Open CFU). Friedman test was used to compare the mean values among the groups, and a Bonferroni correction was made to determine the dissimilar group, with a P = 0.015. Results: At t0 for protocol A the CFU count was 82.8 ± 1.3; protocol B was 9.7 ± 30; protocol C was 0.1 ± 0.3 (P < 0.001). At t1 for protocol A the CFU was 80.7 ± 89.4; protocol B was 7.5 ± 32; protocol C was 0.0 ± 0.0 (P < 0.001). No adverse events were present among the subjects. Conclusion: Ethyl alcohol at 61% with 1% chlorhexidine gluconate showed higher efficacy than the traditional washing antiseptics.
FREE ALGEBRAS OVER A POSET IN VARIETIES
Figallo, Aldo Jr,Ziliani, Alicia Korean Mathematical Society 2011 대한수학회논문집 Vol.26 No.4
In 1945, the notion of free lattice over a poset was introduced by R. Dilworth (Trans. Am. Math. Soc. 57 (1945), 123{154). In this note, a construction of the free algebra over a poset in varieties finitely generated is shown. Finally, this result is applied to different classes of algebras.