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Bogdan Tolea,Alexandru Ionut Radu,Horia Beles,Csaba Antonya 한국자동차공학회 2018 International journal of automotive technology Vol.19 No.1
The goal of this paper is to determine how the geometry of the vehicle’s frontal profile is influencing the pedestrian’s head accelerations (linear and angular) in car-to-pedestrian accidents. In order to achieve this goal, a virtual multibody dummy of the pedestrian was developed and multiple simulations of accidents were performed using vehicles with different frontal profile geometry, from different classes. The type of accidents considered is characteristic for urban areas and occur at relatively low speed (around 30 km/h) when an adult pedestrian is struck from the rear and the head acceleration variation are the measurement of the accident severity. In the accident simulation 3D meshes were applied on the geometry of the vehicles, in order to define the contact surface with the virtual dummy, similar with real vehicles. The validation of the virtual pedestrian dummy was made by performing two crash-tests with a real dummy, using the same conditions as in the simulations. The measured accelerations in the tests were the linear and angular accelerations of the head during the impact, and these were compared with the ones from the simulations. After validating the virtual model of the car-to-pedestrian accident, we were able to perform multiple simulations with different vehicle shapes. These simulations are revealing how the geometric parameters of the vehicle’s frontal profile are influencing the head acceleration. This paper highlights the main geometric parameters of the frontal profile design that influence the head injury severity and the way that the vehicles can be improved by modifying these parameters. The paper presents an approach to determine the “friendliness” of the vehicle’s frontal profile in the car-to-pedestrian collision.
Some Geomechanical Aspects of Geological CO₂Sequestration
Bogdan Orlic 대한토목학회 2009 KSCE Journal of Civil Engineering Vol.13 No.4
Reservoir depletion and subsequent CO₂injection into the depleted geological reservoir induce stress changes that may mechanically damage top seal and wells, or trigger existing faults, creating the leakage pathways for CO₂escape from the reservoir. The role of geomechanics is to assess the mechanical impact of stress changes on seals, wells and faults. Since many hydrocarbon fields are geometrically complex and irregular, and the rock properties are spatially variable, such an assessment can be conveniently done with a numerical modeling of the field. Based on numerical analyses, recommendations can be given regarding the overall suitability of the depleted geological reservoir for CO₂disposal and safe CO₂injection. Reservoir depletion and subsequent CO₂injection into the depleted geological reservoir induce stress changes that may mechanically damage top seal and wells, or trigger existing faults, creating the leakage pathways for CO₂escape from the reservoir. The role of geomechanics is to assess the mechanical impact of stress changes on seals, wells and faults. Since many hydrocarbon fields are geometrically complex and irregular, and the rock properties are spatially variable, such an assessment can be conveniently done with a numerical modeling of the field. Based on numerical analyses, recommendations can be given regarding the overall suitability of the depleted geological reservoir for CO₂disposal and safe CO₂injection.
Some Remarks on the Fragility of Smith Predictors used in Haptics
Bogdan Liacu,Irinel-Constantin Mor?rescu,Claude Andriot,Silviu-Iulian Niculescu,Didier Dumur,Patrick Boucher,Frederic Colledani 제어로봇시스템학회 2011 제어로봇시스템학회 국제학술대회 논문집 Vol.2011 No.10
In this paper, we propose a method to study the fragility of Smith predictor-based controllers used in haptics. Using a geometric approach, we derive a simple approach to examine the fragility of Smith predictors for two cases - constant and uncertain delays. Illustrative examples complete the presentation.
Bogdan Cursaru,Anita-Laura Radu,François-Xavier Perrin,Andrei Sarbu,Mircea Teodorescu,Ana-Mihaela Gavrilă,Celina-Maria Damian,Teodor Sandu,Tanta-Verona Iordache,Anamaria Zaharia 한국고분자학회 2020 Macromolecular Research Vol.28 No.3
In this study, composite hydrogels based on crosslinked polyethylene glycol diacrylate (PEGDA) and natural zeolite, with potential applications for the controlled release of phytoextracts, were synthesized by radical polymerization and characterized herein for the first time. The influence of various synthesis parameters, such as the use of distilled water or rose hip extract as reaction medium, or the percentage of the zeolite in the composite hydrogel upon the morphology, swelling kinetics and the rheological properties was investigated. By conducting polymerization of PEGDA in the rose hip extract, the crosslinking reaction yield was almost 100%, because of the chain transfer reactions of the polyphenols from the rose hip extract. Rose hip release tests were used to evaluate the release profiles of the natural bioactive substances from phytoextracts. The results showed that the hydrogel loaded with 3% zeolite displayed the lowest burst release and the slowest release rates of the extract.
Bogdan Liacu,Cesar Mendez-Barrios,Silviu-Iulian Niculescu,Sorin Olaru 제어로봇시스템학회 2010 제어로봇시스템학회 국제학술대회 논문집 Vol.2010 No.10
This paper addresses the “rade-off” between transparency and stability of some specific bilateral teleoperation systems including communication time-delays. Using a geometric approach, we derive a simple method to study the fragility of the proposed controller for a general 4-channel architecture for bilateral teleoperation with time-delays such that the closed-loop stability as well as the transparency are guaranteed for the overall scheme. Illustrative examples complete the presentation.
Role of Peroral Endoscopic Myotomy (POEM) in the Management of Esophageal Diverticula
Bogdan P. Miutescu,Sarah Khan,Shruti Mony,Mouen A Khashab 대한소화기내시경학회 2020 Clinical Endoscopy Vol.53 No.6
Esophageal diverticula are uncommon; however, when present, they can cause symptoms of dysphagia, regurgitation, and chest pain. Based on location and pathophysiological characteristics, they are classified as pulsion- and traction-type diverticula. In the past, theopen surgical approach was the only treatment available; however, in the past few decades, transoral incisionless approaches in theform of rigid and flexible endoscopy have gained popularity. Diverticular peroral endoscopic myotomy has emerged as an alternativetreatment option. In this paper, we reviewed the role of peroral endoscopic myotomy as a treatment option for different types ofesophageal diverticula. Although a safe and effective procedure, this novel submucosal tunneling technique for the treatment ofesophageal diverticula requires further validation, and head-to-head comparisons between the different approaches for the treatmentof esophageal diverticula are warranted.
Proportional-Derivative (PD) Controllers for Haptics subject to Distributed Time-Delays
Bogdan Liacu,Irinel-Constantin Mor?rescu,Silviu-Iulian Niculescu,Claude Andriot,Didier Dumur,Patrick Boucher,Frederic Colledani 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10
This paper focuses on the stability analysis of Proportional-Derivative (PD) controllers for Multi-Input-Multi-Output (MIMO) systems affected by distributed time-delays. The time-delays will be approximated by the most common distributions (uniform and gamma with gap distributions). In order to provide practical guidelines for the design of PD controllers we describe the stability regions in the gains-parameter space using a geometric approach. Illustrative examples complete the presentation.