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Garcia-Roncero, Herminio,Caballe-Serrano, Jordi,Cano-Batalla, Jordi,Cabratosa-Termes, Josep,Figueras-Alvarez, Oscar The Korean Academy of Prosthodonitics 2015 The Journal of Advanced Prosthodontics Vol.7 No.2
PURPOSE. In this study, a temporal abutment fixation screw, designed to fracture in a controlled way upon application of an occlusal force sufficient to produce critical micromotion was developed. The purpose of the screw was to protect the osseointegration of immediate loaded single implants. MATERIALS AND METHODS. Seven different screw prototypes were examined by fixing titanium abutments to 112 Mozo-Grau external hexagon implants (MG Osseous$^{(R)}$; Mozo-Grau, S.A., Valladolid, Spain). Fracture strength was tested at $30^{\circ}$ in two subgroups per screw: one under dynamic loading and the other without prior dynamic loading. Dynamic loading was performed in a single-axis chewing simulator using 150,000 load cycles at 50 N. After normal distribution of obtained data was verified by Kolmogorov-Smirnov test, fracture resistance between samples submitted and not submitted to dynamic loading was compared by the use of Student's t-test. Comparison of fracture resistance among different screw designs was performed by the use of one-way analysis of variance. Confidence interval was set at 95%. RESULTS. Fractures occurred in all screws, allowing easy retrieval. Screw Prototypes 2, 5 and 6 failed during dynamic loading and exhibited statistically significant differences from the other prototypes. CONCLUSION. Prototypes 2, 5 and 6 may offer a useful protective mechanism during occlusal overload in immediate loaded implants.
Herminio Garcia-Roncero,Jordi Caballe-Serrano,Jordi Cano-Batalla,Josep Cabratosa-Termes,Oscar Figueras-Alvarez 대한치과보철학회 2015 The Journal of Advanced Prosthodontics Vol.7 No.2
PURPOSE. In this study, a temporal abutment fixation screw, designed to fracture in a controlled way upon application of an occlusal force sufficient to produce critical micromotion was developed. The purpose of the screw was to protect the osseointegration of immediate loaded single implants. MATERIALS AND METHODS. Seven different screw prototypes were examined by fixing titanium abutments to 112 Mozo-Grau external hexagon implants (MG Osseous®; Mozo-Grau, S.A., Valladolid, Spain). Fracture strength was tested at 30º in two subgroups per screw: one under dynamic loading and the other without prior dynamic loading. Dynamic loading was performed in a single-axis chewing simulator using 150,000 load cycles at 50 N. After normal distribution of obtained data was verified by Kolmogorov–Smirnov test, fracture resistance between samples submitted and not submitted to dynamic loading was compared by the use of Student›s t-test. Comparison of fracture resistance among different screw designs was performed by the use of one-way analysis of variance. Confidence interval was set at 95%. RESULTS. Fractures occurred in all screws, allowing easy retrieval. Screw Prototypes 2, 5 and 6 failed during dynamic loading and exhibited statistically significant differences from the other prototypes. CONCLUSION. Prototypes 2, 5 and 6 may offer a useful protective mechanism during occlusal overload in immediate loaded implants.
Assembly strategies of wind turbine towers for minimum fatigue damage
Cristina Nunez-Casado,Oscar Lopez-Garcia,Enrique Gomez de las Heras,Alvaro Cuerva-Tejero,Cristobal Gallego-Castillo 한국풍공학회 2017 Wind and Structures, An International Journal (WAS Vol.25 No.6
The aim of this paper is to present a method to obtain the dynamic response of a wind turbine tower in time domain by means of the generation of time series and to estimate the associated fatigue damage by means of a Rainflow counting algorithm. The proposed method is based on assuming the vortex shedding is a bidimensional phenomena and on following a classical modal superposition method to obtain the structure dynamic response. Four different wind turbine tower geometric configurations have been analyzed in a range of usual wind velocities and covering extreme wind velocities. The obtained results have shown that, depending on the turbulence intensity and the mean wind velocity, there are tower geometric configurations more advantageous from the fatigue load standpoint. Consequently, the presented model can be utilized to define assembly strategies oriented to fatigue damage minimization.
Health Monitoring System (HMS) for structural assessment
José Campos e Matos,Oscar Garcia,António Abel Henriques,Josep Vehí,Joan Ramon Casas 국제구조공학회 2009 Smart Structures and Systems, An International Jou Vol.5 No.3
As in any engineering application, the problem of structural assessment should face the different uncertainties present in real world. The main source of uncertainty in Health Monitoring System (HMS) applications are those related to the sensor accuracy, the theoretical models and the variability in structural parameters and applied loads. In present work, two methodologies have been developed to deal with these uncertainties in order to adopt reliable decisions related to the presence of damage. A simple example, a steel beam analysis, is considered in order to establish a liable comparison between them. Also, such methodologies are used with a developed structural assessment algorithm that consists in a direct and consistent comparison between sensor data and numerical model results, both affected by uncertainty. Such algorithm is applied to a simple concrete laboratory beam, tested till rupture, to show it feasibility and operational process. From these applications several conclusions are derived with a high value, regarding the final objective of the work, which is the implementation of this algorithm within a HMS, developed and applied into a prototype structure.
Bile duct injuries after cholecystectomy, analysis of constant risk
Jair Diaz-Martinez,Oscar Chapa-Azuela,Jorge Alberto Roldan-Garcia,Gustavo Alain Flores-Rangel 한국간담췌외과학회 2020 Annals of hepato-biliary-pancreatic surgery Vol.24 No.2
Backgrounds/Aims: The bile duct injuries are the most severe complications that occur after the surgical manipulation of the bile duct. The hepaticojejunostomy remained as the best treatment. Several factors identified that affect the result. This study aimed to analyze and identify risk factors that affected the evolution of these patients. Methods: A retrospective, observational study was conducted from February 1998 to June 2017. We included all patients with bile duct injuries who required surgical treatment. Results: We found 79 patients. The majority had a Bismuth type III in 35.4% (n=28). The morbidity of the Hepaticojejunostomy was 19% (n=15). In short-term follow-up, the main complications were cholangitis 11.4% (n=9) and bile leak 10% (n=8). In the long-term follow-up, in 2.5% (n=2) stricture was presented. On the comparison between postoperative and preoperative parameters, biliary peritonitis after a cholecystectomy (p=0.02) was an independent predictor of postoperative morbidity (p<0.05). Conclusions: In the treatment of bile duct injuries, different factors affect their outcomes. Our results show that infectious complications continue to affect the results of the treatment of bile duct lesions.
Assembly strategies of wind turbine towers for minimum fatigue damage
Nunez-Casado, Cristina,Lopez-Garcia, Oscar,de las Heras, Enrique Gomez,Cuerva-Tejero, Alvaro,Gallego-Castillo, Cristobal Techno-Press 2017 Wind and Structures, An International Journal (WAS Vol.25 No.6
The aim of this paper is to present a method to obtain the dynamic response of a wind turbine tower in time domain by means of the generation of time series and to estimate the associated fatigue damage by means of a Rainflow counting algorithm. The proposed method is based on assuming the vortex shedding is a bidimensional phenomena and on following a classical modal superposition method to obtain the structure dynamic response. Four different wind turbine tower geometric configurations have been analyzed in a range of usual wind velocities and covering extreme wind velocities. The obtained results have shown that, depending on the turbulence intensity and the mean wind velocity, there are tower geometric configurations more advantageous from the fatigue load standpoint. Consequently, the presented model can be utilized to define assembly strategies oriented to fatigue damage minimization.
Health Monitoring System (HMS) for structural assessment
e Matos, Jose Campos,Garcia, Oscar,Henriques, Antonio Abel,Casas, Joan Ramon,Vehi, Josep Techno-Press 2009 Smart Structures and Systems, An International Jou Vol.5 No.3
As in any engineering application, the problem of structural assessment should face the different uncertainties present in real world. The main source of uncertainty in Health Monitoring System (HMS) applications are those related to the sensor accuracy, the theoretical models and the variability in structural parameters and applied loads. In present work, two methodologies have been developed to deal with these uncertainties in order to adopt reliable decisions related to the presence of damage. A simple example, a steel beam analysis, is considered in order to establish a liable comparison between them. Also, such methodologies are used with a developed structural assessment algorithm that consists in a direct and consistent comparison between sensor data and numerical model results, both affected by uncertainty. Such algorithm is applied to a simple concrete laboratory beam, tested till rupture, to show it feasibility and operational process. From these applications several conclusions are derived with a high value, regarding the final objective of the work, which is the implementation of this algorithm within a HMS, developed and applied into a prototype structure.