12 research outputs found
Computations of high‐speed compressible flows with adaptive cell‐centered finite element method
No full textADAPTIVE FINITE ELEMENT METHOD TO DETERMINE K<sub>I</sub> AND K<sub>II</sub> OF CRACK PLATE WITH DIFFERENT E<sub>INCLUSION</sub>/E<sub>PLATE</sub> RATIO
No full text An adaptive finite element method is presented to determine the KI and KII stress intensity factors of crack plate with different inclusions. The paper starts from describing two-dimensional fracture mechanics theory, an adaptive finite element formulation and the reflection photoelastic technique. An adaptive finite element method is evaluated by analyzing two examples. A single edge cracked plate made from polycarbonate. The second example is the slant edge 45° cracked plate subjected to a uniform uniaxial tensile stress. The KI and KII results are found to be function of the crack length per width and the inverse function of E ratio. These examples demonstrate the efficiency of the adaptive finite element method to provide accurate solutions as compared to those from the reflection photoelastic technique. </jats:p
J-5 TEMPERATURE DISTRIBUTION IN ANTERIOR EYE DURING PHACOEMULSIFICATION BY FINITE ELEMENT METHOD(Session: Interface/FEM/CAE)
No full textKI stress intensity factor of cracks with a hard inclusion by finite element method and reflection photoelasticity technique
No full textTransient temperature distribution on the corneal endothelium during ophthalmic phacoemulsification: a numerical simulation using the nodeless variable element
No full textAbstract
Background: During cataract operation (phacoemulsification), a phaco needle-tip is inserted into the anterior chamber of eye. Then, heat is generated by the oscillation of the phaco needle, which may injury the corneal endothelial cells. There are no data available for temperature responses at the corneal endothelium to heat from the phaco needle during phacoemulsification. Objective: Investigate temperature distribution on the corneal endothelium during ophthalmic phacoemulsification using numerical simulation, and compare the transient temperature response to heat between balanced salt solution (BSS) and ophthalmic viscoelastic device (OVD), Viscoat®. Methods: Heat flux from a phaco needle was measured with thermal properties of BSS and AVS in an experimental setting. Then, nodeless variable finite element method was applied to predict temperature changes in the eye by the phaco needle inserted into the anterior chamber. The transient temperature distribution on the corneal endothelium was calculated at 10, 20, and 30 seconds after heat generation by the needle. Results: The heat generation of phaco needle without sleeve cover was 1.6 kW/m2. The numerical simulation showed that the maximum temperature occurs on the wound location at all times after heat generation by the phaco needle. Especially, at time 30 seconds, it was 49.2 and 41.7°C in BSS and OVD, respectively. The temperature elevation by the phaco needle was lower in OVD than BSS. Conclusion: Phacoemulsification is a heat-generating procedure performed between the anterior chamber structures of eye. During this procedure, OVD may protect the corneal endothelium against heat better than BSS.</jats:p
การประมาณค่าขนาดอิทธิพลของลองฟอร์ดและการประยุกต์
No full textวารสารวิชาการและวิจัย มทร.พระนคร, 10 (1) : 193-199Quantitative research synthesis employed statistical methods to synthesize several research papers which were identical in terms of research problems, Meta-Analysis, in order to discover a standard index that was able to synthesize the aforementioned research papers and to measure the quantifiable effects of manipulated variable on the dependent variable. Regarding this article, the author presented and explained Longford’s estimation of effect size, which is one of the most efficient and recent estimations. The study proved the background and functional model of the estimator of effect size. In addition, the calculation examples following the estimator of Longford’s effect size were demonstrated by meta-analysis.Rajamangala University of Technology Phra Nakho
Whole blood viscosity modeling using power law, Casson, and Carreau Yasuda models integrated with image scanning U-tube viscometer technique
No full textThis study presented the image scanning U-tube viscometer technique to measure the whole blood viscosity. Two
different constitutive models, power law and Casson, were selected to calculate blood viscosity. Results were compared with
rotating viscometer. They had a good agreement at higher shear rates. Three constitutive models power law, Casson and
Carreau Yasuda models were applied to blood viscosity data and used to simulate transient blood height in the U-tube.
Comparison of the U-tube simulation and the actual experiment showed that Carreau Yasuda model is the most accurate
model for whole blood viscosity measurement
Process Development for Fabricating 3D-Printed Polycaprolactone-Infiltrated Hydroxyapatite Bone Graft Granules: Effects of Infiltrated Solution Concentration and Agitating Liquid
No full textBone grafts are commonly used in orthopedic and dental surgeries to facilitate bone repair and regeneration. A new type of bone graft, polycaprolactone-infiltrated three dimensionally printed hydroxyapatite (3DP HA/PCL), was previously developed by infiltrating polycaprolactone (PCL) into preformed three-dimensional-printed hydroxyapatite (3DP HA) that was fabricated using binder jetting technology combined with a low-temperature phase transformation process. However, when producing small granules, which are often used for bone grafting, issues of granule agglomeration emerged, complicating the application of this method. This study aimed to develop a fabrication process for 3DP HA/PCL bone graft granules using solution infiltration and liquid agitation. The effects of varying PCL solution concentrations (40% and 50% w/w) and different agitating liquids (deionized water or DI, N-Methyl-2-Pyrrolidone or NMP, and an NMP-DI mixture) on the properties of the resulting composites were investigated. XRD and FTIR analysis confirmed the coexistence of HA and PCL within the composites. The final PCL content was comparable across all conditions. The contact angles of 3DP HA/PCL were 26.3 and 69.8 degree for 40% and 50% PCL solution, respectively, when using DI, but were zero when using NMP and NMP-DI. The highest compression load resistance and diametral tensile strength were achieved using the 50% PCL solution with DI or the NMP-DI mixture. DI resulted in a dense PCL coating, while NMP and the NMP-DI mixture produced a porous and irregular surface morphology. All samples exhibited a porous internal microstructure due to PCL infiltration into the initial pores of the 3D-printed HA. Biocompatibility tests showed that all samples supported the proliferation of MC3T3-E1 cells, with the greatest OD values observed for the 50% PCL solution with DI or the NMP-DI mixture at each cultured period. Considering the microstructural, mechanical, and biological properties, the 50% PCL solution with the NMP-DI mixture demonstrated overall desirable properties
Effects of forest and agricultural land use on flood unit hydrographs
Get PDFJuly 1977.Bibliography: pages 20-21
Biomechanical Simulation and Comparison of Scepter Plate and PHILOS Systems for Greater Tuberosity Humerus Fracture Fixation
Get PDFThis paper presents a biomechanical study of a proximal humerus locking plate (PHILOS) and a new locking plate for the humerous fracture treatment of greater tuberosity. A new locking plate is designed in a scepter shape. Fiber wire is applied to reduce the number of screws. The finite element model was conducted to evaluate the biomechanical behavior of the scepter locking plate-screw-wire fixation under natural loading conditions, i.e., contraction force 200 N and 100 N on supraspinatus and infraspinatus tendons, respectively, and compared to the PHILOS plate-screw-wire fixation. The model consists of cortical bones of the humerus, supraspinatus and infraspinatus tendons, both locking plates, screws, and fiber wires. The maximum von Mises stress and factor of safety on the PHILOS plate and scepter locking plate are 334.1 N/mm2, 2.07, and 590.9 N/mm2, 1.17, respectively. The maximum strain of two crack surfaces and maximum displacement of fracture gap of the PHILOS system model and scepter locking plate system model were 0.3937%, 0.54 mm, and 0.492%, 0.49 mm, respectively. The proper strain and maximum displacement of fracture gap that can promote primary healing are less than 2% and 1 mm, respectively. The results indicate that the scepter locking plate-screw-wire fixation exhibits comparable or non-inferior biomechanical behavior and no effect on the healing process, including stiffness and stress concentration, but 21% smaller, 45% shorter, and 74% lower volume and weight than the PHILOS plate-screw-wire fixation. The scepter locking plate also obtains smaller incisions and reduces soft tissue trauma. These findings suggest that the scepter locking plate design, including screw-wire fixation, is more specifically tailored to the humerus fracture treatment of greater tuberosity than PHILOS plate-screw-wire fixation and may offer advantages in surgical technique and outcome. This scepter locking plate system could be a viable alternative for the fracture treatment of greater tuberosity
