The Experts below are selected from a list of 165 Experts worldwide ranked by ideXlab platform
Jeen-hwa Wang - One of the best experts on this subject based on the ideXlab platform.
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Inertial Effect on Interaction between Two Earthquake Faults
Annals of Geophysics, 2020Co-Authors: Jeen-hwa WangAbstract:This study is focused on the inertial effect on slip of and interaction between two earthquake faults based on a two-body slider-slider model in the presence of thermal-pressurized slip-weakening friction and viscosity. The ratio m = m 2 / m 1 , where m 2 and m 1 are the masses of sliders 1 and 2, respectively, is the model parameter to represent the inertial effect. Other model parameters are s (the stiffness ratio), f= f o2 /f o1 (where f oi is the normalized static friction force on the i -th slider, i =1, 2), y=U c2 /U c1 (where U ci is the normalized characteristic displacement of friction law on the i -th slider), and g=h 2 /h 1 (where h i is the normalized viscosity coefficient between the i -th slider and the Background Plate). Simulation results show that m is important on interaction between the two sliders. Foreshocks and aftershocks/afterslip can be generated on slider 1 or slider 2 when m ≠1. Slider 2 behaves like a slow event when m ≥50. The f, y , and g are the major factors and s is minor one in causing time delay between the two sliders. Slider 2 cannot move when f is higher than a critical value which depends on other model parameters. Interaction and the patterns of motions of the two sliders are different between y 1. The presence of viscosity may increase the predominant period of a slider.
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Can the Nucleation Phase be Generated on a Sub-fault Linked to the Main Fault of an Earthquake?
2018Co-Authors: Jeen-hwa WangAbstract:Abstract. We study the effects of seismic coupling, friction, viscous, and inertia on earthquake nucleation based on a two-body spring-slider model in the presence of thermal-pressurized slip-dependent friction and viscosity. The stiffness ratio of the system to represent seismic coupling is the ratio of coil spring K between two sliders and the leaf spring L between a slider and the Background Plate and denoted by s = K/L. The s is not a significant factor in generating the nucleation phase. The masses of the two sliders are m1 and m2, respectively. The frictional and viscous effects are specified by the static friction force, fo, the characteristic displacement, Uc, and viscosity coefficient, h, respectively. Numerical simulations show that friction and viscosity can both lengthen the natural period of the system and viscosity increases the duration time of motion of the slider. Higher viscosity causes lower particle velocities than lower viscosity. The ratios γ = h2/h1, φ = fo2/fo1, ψ = Uc2/Ucl, and μ = m2/m1 are four important factors in influencing the generation of a nucleation phase. When s > 0.17, γ > 1, 1.15 > φ > 1, ψ
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Multistable Slip of a One-degree-of-freedom Spring-slider Model in the Presence of Thermal-pressurized Slip-weakening Friction and Viscosity
Nonlinear Processes in Geophysics, 2017Co-Authors: Jeen-hwa WangAbstract:Abstract. This study is focused on multistable slip of earthquakes based on a one-degree-of-freedom spring-slider model in the presence of thermal-pressurized slip-weakening friction and viscosity by using the normalized equation of motion of the model. The major model parameters are the normalized characteristic displacement, Uc, of the friction law and the normalized viscosity coefficient, η, between the slider and Background Plate. Analytic results at small slip suggest that there is a solution regime for η and γ ( = 1∕Uc) to make the slider slip steadily. Numerical simulations exhibit that the time variation in normalized velocity, V∕Vmax (Vmax is the maximum velocity), obviously depends on Uc and η. The effect on the amplitude is stronger due to η than due to Uc. In the phase portrait of V∕Vmax versus the normalized displacement, U∕Umax (Umax is the maximum displacement), there are two fixed points. The one at large V∕Vmax and large U∕Umax is not an attractor, while that at small V∕Vmax and small U∕Umax can be an attractor for some values of η and Uc. When Uc 1, the related Fourier spectra show only one peak, thus suggesting linear behavior of the system.
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Multistable Slip of a One-degree-of-freedom Spring-slider Model in the Presence of Thermal-pressurized Slip-weakening Friction and Viscosity
2017Co-Authors: Jeen-hwa WangAbstract:Abstract. This study is focused on multistable slip of earthquakes based on a one-degree-of-freedom slider-slider model in the presence of thermal-pressurized slip-weakening friction and viscosity by using the normalized equation of motion of the model. The major model parameters are the normalized characteristic displacement, Uc, of the friction law and the normalized viscosity coefficient, η, between the slider and Background Plate. Analytic results at small slip suggest that there is a solution regime for η and γ (= 1 / Uc) to make the slider slip steadily. Numerical simulations exhibit that the time variation in normalized velocity, V / Vmax (Vmax is the maximum velocity), obviously depends on Uc and η. The effect on the amplitude is stronger due to η than due to Uc. In the phase portrait of V / Vmax versus the normalized displacement, U / Umax (Umax is the maximum displacement), there are two fixed points. The one at large V / Vmax and large U / Umax is not an attractor; while that at small V / Vmax and small U / Umax can be an attractor for some values of η and Uc. When Uc
Peter Kloen - One of the best experts on this subject based on the ideXlab platform.
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what is the hardware removal rate after anteroinferior plating of the clavicle a retrospective cohort study
Journal of Shoulder and Elbow Surgery, 2017Co-Authors: Thomas P A Baltes, Johanna C E Donders, Peter KloenAbstract:Background Plate position in the operative treatment of displaced midshaft clavicle fractures or nonunions is most often on the superior side. However, superior clavicular plating often results in complaints of Plate prominence and local soft tissue irritation, necessitating hardware removal. We have used anteroinferior placement of the Plate in the hope of increasing biomechanical stability and fixation and also of lowering complaints of Plate prominence and soft tissue irritation. In this report, we set out to study the percentage of hardware removal in our group of patients treated with anteroinferior plating of the clavicle after long-term follow-up. Methods In this retrospective review, we evaluated all patients who were surgically treated with anteroinferior plating for midshaft clavicle fracture, delayed union, or nonunion by the senior author between February 2003 and July 2015. Patients required a minimum age of 16 years at time of surgery and a follow-up of >12 months. Patients with malunion, plating on the superior aspect, or double plating were excluded. Results The medical records of 53 patients (54 fractures) were reviewed after a mean follow-up duration of 6.4 years (range, 1.1-13.1). The mean age at follow-up was 47.8 years (range, 20.4-80.7). All fractures and nonunions healed. In only 3 cases (5.6%), hardware removal was requested by the patient because of Plate prominence. Conclusions Anteroinferior plating of midshaft clavicle fractures, delayed unions, and nonunions resulted in low hardware removal rates in our cohort.
Thomas P A Baltes - One of the best experts on this subject based on the ideXlab platform.
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what is the hardware removal rate after anteroinferior plating of the clavicle a retrospective cohort study
Journal of Shoulder and Elbow Surgery, 2017Co-Authors: Thomas P A Baltes, Johanna C E Donders, Peter KloenAbstract:Background Plate position in the operative treatment of displaced midshaft clavicle fractures or nonunions is most often on the superior side. However, superior clavicular plating often results in complaints of Plate prominence and local soft tissue irritation, necessitating hardware removal. We have used anteroinferior placement of the Plate in the hope of increasing biomechanical stability and fixation and also of lowering complaints of Plate prominence and soft tissue irritation. In this report, we set out to study the percentage of hardware removal in our group of patients treated with anteroinferior plating of the clavicle after long-term follow-up. Methods In this retrospective review, we evaluated all patients who were surgically treated with anteroinferior plating for midshaft clavicle fracture, delayed union, or nonunion by the senior author between February 2003 and July 2015. Patients required a minimum age of 16 years at time of surgery and a follow-up of >12 months. Patients with malunion, plating on the superior aspect, or double plating were excluded. Results The medical records of 53 patients (54 fractures) were reviewed after a mean follow-up duration of 6.4 years (range, 1.1-13.1). The mean age at follow-up was 47.8 years (range, 20.4-80.7). All fractures and nonunions healed. In only 3 cases (5.6%), hardware removal was requested by the patient because of Plate prominence. Conclusions Anteroinferior plating of midshaft clavicle fractures, delayed unions, and nonunions resulted in low hardware removal rates in our cohort.
Hiroshi Arino - One of the best experts on this subject based on the ideXlab platform.
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Treatment of Distal Clavicle Fractures using a Scorpion Plate and Influence of Timing on Surgical Outcomes: A Retrospective Cohort Study of 105 Cases
2020Co-Authors: Ryogo Furuhata, Masaaki Takahashi, Teppei Hayashi, Miyu Inagawa, Aki Kono, Noboru Matsumura, Yusaku Kamata, Hiroshi Arino, Hideo MoriokaAbstract:Abstract Background Plate fixation is an established method for treating unstable distal clavicle fractures. However, the appropriate timing of surgery for acute distal clavicle fractures remains unclear. The present study aimed to evaluate the clinical outcomes of osteosynthesis using a Scorpion Plate and to assess the influence of surgery timing on the surgical outcomes for acute unstable distal clavicle fractures. Methods We retrospectively reviewed 105 patients who underwent fixation for acute unstable distal clavicle fractures (Neer type II and V) using the Scorpion Plate between 2008 and 2018. Patients were divided into early (45 patients) and delayed (60 patients) treatment groups based on the timing of the surgical intervention (within or after seven days). The outcomes were postoperative complications (nonunion, peri-implant fracture, Plate loosening, Plate-related pain, and stiffness). We evaluated the outcomes from X-ray radiographs and clinical notes. Results Among the 105 patients, nonunion, Plate loosening, Plate-related pain, and stiffness were observed in six patients (5.7%), four patients (3.8%), seven patients (6.7%), and one patient (1.0%), respectively. The nonunion rate was significantly higher in the delayed treatment group than that in the early treatment group (P=0.036). Although the difference was not significant, Plate loosening and stiffness were only observed in the delayed treatment group. Conclusion Our results demonstrated that osteosynthesis using Scorpion Plates achieved satisfactory surgical outcomes for unstable distal clavicle fractures . In addition, this study suggested that performing surgery within six days after injury is recommended to reduce postoperative complications .
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Treatment of Distal Clavicle Fractures using a Scorpion Plate and Influence of Timing on Surgical Outcomes: A Retrospective Cohort Study of 105 Cases
2019Co-Authors: Ryogo Furuhata, Masaaki Takahashi, Teppei Hayashi, Miyu Inagawa, Aki Kono, Noboru Matsumura, Yusaku Kamata, Yasuhiro Kiyota, Akira Yoshiyama, Hiroshi ArinoAbstract:Abstract Background Plate fixation is the established method of treating unstable distal clavicle fractures. However, the appropriate timing of surgery for acute distal clavicle fractures remains unclear. The present study aimed to evaluate the clinical outcomes of osteosynthesis using a Scorpion Plate and to assess the influence of surgery timing on the surgical outcomes for acute unstable distal clavicle fractures. Methods We retrospectively reviewed 105 patients who underwent fixation for acute unstable distal clavicle fractures (Neer type II and V) using the Scorpion Plate between 2008 and 2018. Patients were divided into early (45 patients) and delayed (60 patients) treatment groups based on the timing of the surgical intervention (within or after seven days). The outcomes were postoperative complications (delayed union, peri-implant fracture, Plate loosening, Plate-related pain, and stiffness). We evaluated the outcomes from X-ray radiographs and clinical notes.Results Among the 105 patients, delayed union, Plate loosening, Plate-related pain, and stiffness were observed in six patients (5.7%), four patients (3.8%), seven patients (6.7%), and one (1.0%) patient, respectively. The delayed union rate was significantly higher in the delayed treatment group than that in the early treatment group (P=0.036). Although the difference was not significant, Plate loosening and stiffness were only observed in the delayed treatment group. Conclusion Our results demonstrated that osteosynthesis using Scorpion Plates achieved satisfactory surgical outcomes for unstable distal clavicle fractures . In addition, this study suggested that performing surgery within six days after injury is recommended to reduce postoperative complications .
Ai Hong Chen - One of the best experts on this subject based on the ideXlab platform.
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Comparison of visibility threshold on different chromatic contrast objects / Saiful Azlan Rosli … [et al.]
2020Co-Authors: Saiful Azlan Rosli, Anis Zahirah Aladin, Nurulain Muhamad, Ai Hong ChenAbstract:The aim of this study was to compare the visibility threshold of eight Plates with different chromatic contrast. The staircasepsychophysics method based on the resolution of gaps in Landolt C was used to determine the average visibility threshold. Thirty young adults with best-corrected visual acuity of 6/6, normal colour perception and no history of ocular diseases were recruited. The results showed a combination of white on blue Background Plate gave a highest visibility level (mean=44.48±6.37m), while red on a blue Background was the least visible combination (mean=33.30±4.68m). In conclusion, the chromatic contrast of an object can affect the visibility threshold.
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Comparison of Visibility Threshold on Different Chromatic Contrast Objects
Social and Management Research Journal, 2016Co-Authors: Saiful Azlan Rosli, Anis Zahirah Aladin, Nurulain Muhamad, Ai Hong ChenAbstract:The aim of this study was to compare the visibility threshold of eight Plates with different chromatic contrast. The staircase psychophysics method based on the resolution of gaps in Landolt C was used to determine the average visibility threshold. Thirty young adults with best-corrected visual acuity of 6/6, normal colour perception and no history of ocular diseases were recruited. The results showed a combination of white on blue Background Plate gave a highest visibility level (mean=44.48±6.37m), while red on a blue Background was the least visible combination (mean=33.30±4.68m). In conclusion, the chromatic contrast of an object can affect the visibility threshold. Keywords: chromatic contrast, visibility threshold
