Search results for " surface"
showing 10 items of 2838 documents
Improved Performance in Quadrotor Trajectory Tracking Using MIMO PIλ-D Control
2022
This paper aims to develop a fractional control approach for quadrotor trajectory tracking. A fractional-order integrator (PIλ) with a feedback derivative scheme is designed to control each state of the MIMO system. The designed feedback controller stabilizes the initially unstable decoupled states and widens the stability, while PIλ provides precise trajectory tracking capabilities. After a successful simulation study, the new PIλ-D controller is implemented in the hardware environment. The various performance and load disturbance analyses reveal the effectiveness of the proposed scheme compared with the classical PD/PID controllers. The real-time study also shows that this scheme is a sim…
Efficiency enhancement of organic light emitting diodes by NaOH surface treatment of the ITO anode
2009
Abstract Organic light emitting diodes (OLEDs) based on tris-(8-idroxyquinoline)aluminum (Alq 3 ) with enhanced efficiency are reported here. This is obtained by improving the charge carrier balance, through a preliminary NaOH surface treatment of the indium tin oxide (ITO) anode, in order to decrease its work function and, consequently, reduce the hole injection. The obtained devices exhibit a 1.36% external quantum efficiency and a 1.2 lm/W power efficiency at a current density of 60 mA/cm 2 . These values are more than double as compared with those of identical reference devices fabricated without the preliminary NaOH surface treatment.
In vitro evaluation of shear bond strength of orthodontic stainless steel brackets using transillumination
2018
Background The objective of this study was to compare the effect of transillumination techniques to conventional light curing on shear bond strength (SBS) and adhesive remnant index (ARI) of orthodontic stainless steel brackets. Material and Methods 240 extracted human maxillary incisors, canines and premolars were randomly separated into four control and four experimental groups, based on tooth type. Labio-lingual thickness was measured. Control groups were light cured from buccal surface and experimental groups from lingual surface (transillumination) from four directions (mesial-distal, incisal-direct, direct, mesial-distal-incisal). SBS was measured using an Instron machine and ARI eval…
Dental caries experience, tooth surface distribution and associated factors in 6- and 13- year- old school children from Davangere, India
2012
Objectives: The objective of the present study was to investigate the caries experience and patterns in a sample of 6- and 13- year old school children and to estimate the contributing roles of the likely risk indicators. Study design: Data were obtained from 400 (196, 6-year old and 204, 13-year old) school children. A questionnaire was sent to the children parents to measure socioeconomic, socio-demographic, and behavioral variables. Dental caries detection was performed according to the World Health Organization criteria (dmft and DMFT). The mean dmft/DMFT scores were analysed either as a continuous (calculating means and standard deviations) or as a categorical variable (providing propo…
Determination of the facial/oral alveolar crest using RF-echograms. An in vitro study on the periodontium of pigs.
1989
Abstract This study is a part of a research project in which we have been investigating the use of the ultrasonic pulse echo technique as a means of determining in vivo the facial/oral alveolar crest precisely and routinely. Here, RF-echograms are presented, showing the facial/oral periodontium of pigs. These echograms have been produced using a focussed 20 MHz transducer and a special design of an ultrasonic measuring and analysis system. In one series of measurements on macerated periodontia of pigs we found out that RF-echograms characteristic of a particular level of the facial/oral pericrestal aspect can be achieved. Based upon these results, we succeeded in determining exactly the hei…
Ultrasonic B-scans of the facial/oral periodontium in pigs.
1989
In vitro ultrasonic scans of the oral/facial periodontium of pigs were obtained using a special experimental design and with the help of a newly developed ultrasonic measuring and analysis system. These two-dimensional images distinguish themselves from the one-dimensional RF-echograms and A-scans in that they enable the viewer to have a quick overview of the relationship between different interfaces in a scanned sector. A selection of ultrasonic B-scans proves that the scanned tissues such as gingiva, bone, periodontal ligament, tooth surface and even structures of the inner part of the tooth may be clearly imaged and distinctly differentiated. Furthermore, we demonstrate with manipulation…
Conical connection adjustment in prosthetic abutments obtained by different techniques
2019
Background The goal of this study is to compare the misfit (>150µm) generated once the restoration, made by different techniques, is retained to a single conical implant. Material and methods 15 internal connection implants (MIS C1 4'20x10mm) are embedded each one perpendicularly to an horizontal surface of the 1x1x2cm poliuretan resin model. The 15 samples obtained are divided in 5 groups depending on the framework process (n=3): 1/casting, 2/overcasting, 3/Ti-base, 4/milling and 5/laser sintering. The cobalt-chromium alloy frameworks are screw-retained to their respective implants to a 30-Ncm torque. Once it is retained the framework to the implant, the next step is to section the sample …
Assessment of the Elastographic and Electromyographic of Pelvic Floor Muscles in Postmenopausal Women with Stress Urinary Incontinence Symptoms
2021
Background. Shear wave elastography is an effective method for studying the condition of various musculoskeletal soft tissues. The primary aim of this study was the objective elastographic and electromyographic assessment of the pelvic floor during the rest and contraction of the pelvic floor muscles (PFM) in postmenopausal women. Methods. This was a prospective observational study that was carried out at the University Hospital in Wroclaw, Poland, between January 2017 and December 2019. Patients. The target group of the study included postmenopausal women with stress urinary incontinence. The primary outcomes were the features of the elastographic assessment of the pelvic floor during rest…
Orthodontics and veneers to restore the anterior guidance. A minimally invasive approach
2017
Tooth wear is defined as the progressive loss of a tooth's surface due to actions other than those which cause tooth decay or dental trauma. It is a pathological condition with an increasing prevalence among young people. The aim of this article is to describe an alternative treatment modality to rehabilitate the anterior guidance by a minimally invasive interdisciplinary ortho-restorative treatment. Two patients came to the dental clinic for restorative treatment in order to rehabilitate the worn anterior dentition. Clinical analysis showed tooth surface loss located at the incisal edges by attrition due to an inadequate anterior guidance. In both cases the occlusal vertical dimension was …
Occlusal Surface Achieved Using the Stamp Technique
2020
Abstract Dental occlusion can be restored through preparation, modelling, occlusal adjustment and finishing or by reproducing the final future tooth surface. The micro-brush stamp technique is a new technique used in direct restorations. The purpose of this paper is to present a fast way of restoring the occlusal surface of a tooth when a previous correct functional impression of the surface exists. We will approach, step by step, the occlusal dental tissue reconstruction using a dental flowable composite and a microbrush to get a stamp of the occlusal surface in order to achieve precise occlusal topography.