scholarly journals FEM Based Study for Estimation of Applanation Force and Influence of Intraocular Pressure on Tonometry

2021 ◽  
Author(s):  
Bharathi Bhat ◽  
Rakshath G. Poojary ◽  
Gopalakrishna Prabhu ◽  
Ramesh S. Ve
Keyword(s):  
Intraocular Pressure ◽  
Internal Structure ◽  
Maximum Stress ◽  
Technology Innovation ◽  
Testing Procedure ◽  
Feedback Mechanism ◽  
Eye Care ◽  
Maximum Deformation ◽  
Biomechanical Simulation ◽  
Additional Feedback

Abstract Purpose: Excess force on cornea during eye care testing procedure such as tonometry may damage the internal structure of eye or may result in erroneous results. The proposed work can be utilized or incorporated as an additional feedback mechanism in the technology innovation of design of eye care instruments. Method: This work is focused on biomechanical simulation of human eye to determine applanation force on cornea and also to find the influence of intraocular pressure (IOP) of eye on Tonometry. Results: The results summarise that force applied by the tonometer will increase linearly for increase in deformation of cornea and the junction of cornea and sclera will undergo maximum deformation and hence will experience maximum stress compared to the centre of cornea where tonometer applanates the cornea. Conclusion: The tonometry will result in deformation of cornea in vertical elongation and the maximum stress is concentrated at the tonometer periphery as well as at the junction of cornea and sclera. The investigation also report that rise in IOP of eye demands higher force of applanation to get the prescribed deformation of cornea.

Bionic design of the tower for wind turbine

2021 ◽  
pp. 095440622110046
Author(s):  
Yuqiao Zheng ◽  
Fugang Dong ◽  
Huquan Guo ◽  
Bingxi Lu ◽  
Zhengwen He
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Maximum Stress ◽  
Natural Frequencies ◽  
Bionic Design ◽  
Analytic Hierarchy ◽  
Element Analysis ◽  
Maximum Deformation ◽  
Overall Stability ◽  
Biological Selection

The study obtains a methodology for the bionic design of the tower for wind turbines. To verify the rationality of the biological selection, the Analytic Hierarchy Procedure (AHP) is applied to calculate the similarity between the bamboo and the tower. Creatively, a bionic bamboo tower (BBT) is presented, which is equipped with four reinforcement ribs and five flanges. Further, finite element analysis is employed to comparatively investigate the performance of the BBT and the original tower (OT) in the static and dynamic. Through the investigation, it is suggested that the maximum deformation and maximum stress can be reduced by 5.93 and 13.75% of the BBT. Moreover, this approach results in 3% and 1.1% increase respectively in the First two natural frequencies and overall stability.

Analysis and Optimization of the Static and Dynamic Characteristics of Head Frame

2011 ◽  
Vol 418-420 ◽  
pp. 2055-2059 ◽  
Author(s):  
Yu Lin Wang ◽  
Na Jin ◽  
Kai Liao ◽  
Rui Jin Guo ◽  
Hu Tian Feng
Keyword(s):  
Machine Tool ◽  
Dynamic Characteristics ◽  
Maximum Stress ◽  
Dynamic Performance ◽  
Mode Shapes ◽  
Cnc Machine ◽  
Static And Dynamic Characteristics ◽  
Maximum Deformation ◽  
Improvement Measures ◽  
Optimal Measure

The head frame is a key component which plays a supportive and accommodative role in the spindle system of CNC machine tool. Improving the static and dynamic characteristics has profound significance to the development of machine tool and product performance. The simplified finite element modal is established with ANSYS to carry out the static and modal analysis. The results showed that the maximum deformation of the head frame was 0.0066mm, the maximum stress was 3.94Mpa, the deformation of most region was no more than 0.0007mm, which all verified that the head frame had a good stiffness and deforming resistance; several improvement measures for dynamic performance were also proposed by analyzing the mode shapes, and the 1st order natural frequency increased 7.33% while the head frame mass only increased 1.58% applying the optimal measure, which improved the dynamic characteristics of the head frame effectively.

Eye care in the intensive care unit: intraocular pressure in prone patients with COVID-19

2020 ◽  
Vol 81 (7) ◽  
pp. 1-1
Author(s):  
Sundeep Deol ◽  
Sameer Hanna-Jumma ◽  
Konstantinos T Tsaousis
Keyword(s):  
Intensive Care Unit ◽  
Intensive Care ◽  
Intraocular Pressure ◽  
Eye Care

Statics Analysis for the Crossbeam of Large Gantry CNC Machine under Six Working Conditions

2012 ◽  
Vol 605-607 ◽  
pp. 1523-1526
Author(s):  
Xiao Lei Deng ◽  
Wei Min Yang ◽  
Jian Chen Wang
Keyword(s):  
Stress Distribution ◽  
Working Conditions ◽  
Maximum Stress ◽  
Analysis Method ◽  
Cnc Machine ◽  
Total Deformation ◽  
Optimization Analysis ◽  
Work Requirements ◽  
Maximum Deformation ◽  
Machining Errors

The crossbeam is one of the main supporting parts of large gantry CNC machines. The deformation of the crossbeam under loads at work has great impact on integrated machining errors of machines. However, the crossbeam assembly’s structure and the corresponding loads are so complex that it’s difficult to get them through experiences and analytic methods. In this paper, the FE statics analysis method is used to simulate and analysis of the crossbeam under six main working conditions, obtaining deformation and stress distribution of the crossbeam under each conditions. The results show that when the slippery saddle is at the middle of the crossbeam and the ram extends to 100% length (the distance between the end of ram and the bottom of slippery saddle is 1.29 m), the total deformation of the crossbeam assembly is 6.4914 × 10-5m, the maximum deformation is up to 3.4872 × 10-5m, and the maximum stress is 1.1882 × 107Pa appearing at the hole of the drive shaft. The design of the crossbeam can meet the work requirements well. And analysis results present a basis for further optimization analysis and structural improvements of the crossbeam.

scholarly journals Prolactin secretory rhythm of mated rats induced by a single injection of oxytocin

2006 ◽  
Vol 290 (3) ◽  
pp. E566-E572 ◽  
Author(s):  
Marcel Egli ◽  
Richard Bertram ◽  
Natalia Toporikova ◽  
Michael T. Sellix ◽  
Wilfredo Blanco ◽  
...  
Keyword(s):  
Single Injection ◽  
Anterior Lobe ◽  
Time Of Day ◽  
Feedback Mechanism ◽  
Network Function ◽  
Ovx Rats ◽  
Inhibitory Feedback ◽  
Additional Feedback ◽  
Secretory Pattern ◽  
Da Release

Mating or vaginocervical stimulation [copulatory stimulus (CS)] induces two daily surges of the hormone prolactin (PRL) in rats. This unique secretory pattern of PRL surges is characteristic for the first half of pregnancy and is also present in ovariectomized (OVX) rats. Studies have shown that CS additionally provokes an acute release of the hormone oxytocin (OT). In this study, we tested whether a single injection of OT (iv) is sufficient to initiate the PRL secretion pattern of OVX/CS rats. Furthermore, we measured the 24-h profile of dopamine (DA) content in the anterior lobe of the pituitary gland, because DA is the major inhibitory factor of PRL secretion. The results indicated that a single injection of OT induces a PRL secretory rhythm and a DA release pattern similar to that initiated by CS. Immunocytochemical investigation showed that particular OTergic neurons in the hypothalamus express receptors for PRL, as well as for vasoactive intestinal polypeptide, which indicates an involvement in generating the PRL rhythm and entraining it to the ambient photoperiod. On the basis of this study, we suggest that the PRL-DA inhibitory feedback loop between lactotrophs and DAergic neurons plays a crucial role in generating the oscillatory PRL secretion pattern in CS rats. A timing signal, likely provided by the hypothalamic suprachiasmatic nucleus, entrains the autonomous PRL oscillation to a particular time of day. Mathematical modeling was used to illustrate the proposed network function. The experimental results further suggest an additional feedback mechanism in which certain hypothalamic OTergic neurons are influenced by PRL.

scholarly journals Epidemiological Properties of Primary Open Angle Glaucoma in Nigeria

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Lawan Abdu
Keyword(s):  
Intraocular Pressure ◽  
Primary Open Angle Glaucoma ◽  
Open Angle Glaucoma ◽  
High Reliability ◽  
Treatment Options ◽  
Late Presentation ◽  
Open Angle ◽  
Long Term Effects ◽  
Eye Care

Background. Primary open angle glaucoma (POAG) is progressive chronic optic neuropathy in adults in which intraocular pressure (IOP) and other currently unknown factors contribute to damage. POAG is the second commonest cause of avoidable blindness in Nigeria.Pattern of Presentation. POAG is characterized by late presentation. Absence of pain which is a driving force for seeking medical help, inadequacy of trained eye care personnel, paucity of facilities, misdistribution of resources, lack of awareness, poor education, and poverty may all contribute to this. Medical and surgical treatment options available are challenging and tasking.Screening for Glaucoma. Screening is the presumptive identification of unrecognized disease (POAG) by applying test(s) which can be applied rapidly. Such test(s) should be of high reliability, validity, yield, acceptable, and cost effective. The test should ideally be sensitive, specific, and efficient. It is difficult to select a suitable test that meets these criteria. Intraocular pressure (IOP) appears to be the easiest option. But, high IOP is not diagnostic nor does normal value exclude the disease. Health education is a possible strategy in early case detection and management.Treatment of POAG. Glaucoma treatment can either be medical or surgical (this includes laser). Considering unavailability, potency, cost, and long-term effects of medication, surgery (trabeculectomy) could be a better option. Laser trabeculoplasty is available in a few centers. Viscocanalostomy is not routinely performed. Patient education is vital to success as management is for life.Conclusion. POAG remains a cause of avoidable blindness in Nigeria. There is need for long-term strategy to identify patients early and institute prompt management. Improvement in training of eye care personnel and provision of up to date equipment is essential in achieving this goal.

Finite Element Analysis on Mechanical Properties of Lathe Spindle

2013 ◽  
Vol 378 ◽  
pp. 97-101 ◽  
Author(s):  
Y.M. Yu
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Maximum Stress ◽  
Practical Significance ◽  
Production Cycle ◽  
Vibration Modes ◽  
Ansys Software ◽  
Element Analysis ◽  
Maximum Deformation

The ANSYS software was used to carry out finite element analysis on the mechanical properties of lathe spindle, taking C7620 lathe as research object. By static analysis, the maximum deformation and maximum stress value of spindle in specific operation were determined. Furthermore, spring-damper element was adopted to simulate elastic supports of bearing in dynamic analysis, and then the natural frequencies of the first five ranks and vibration modes of spindle were obtained. The research results in this paper have theoretical and practical significance in optimizing the design of lathe spindle parts and shortening production cycle.

scholarly journals SIMULASI PENGARUH ORIENTASI SUDUT SERAT TERHADAP TEGANGAN TARIK LAMINATED COMPOSITE

2021 ◽  
Vol 4 (01) ◽  
pp. 07-12
Author(s):  
Hilmi Iman Firmansyah ◽  
Sulistyono Sulistyono ◽  
Hangga Wicaksono
Keyword(s):  
Tensile Strength ◽  
Composite Material ◽  
Carbon Fiber ◽  
Maximum Stress ◽  
Laminated Composite ◽  
Carbon Fiber Composites ◽  
Maximum Deformation ◽  
Fiber Angle ◽  
The Matrix ◽  
Angle Orientation

Composite is a material consisting of a mixture or combination of two or more materials, either micro or macro, where the properties of the material are different in shape and chemical composition from the original substance. In this study, the composite was tested to determine the tensile strength using simulation. Composite material modeling consists of carbon fiber as reinforcement and epoxy resin as the matrix. Then the composite material was given a uniaxial loading with a loading value of 50 N. By using variations in the orientation of the fiber angle 45ᵒ/90ᵒ/-45ᵒ, 45ᵒ/90ᵒ/-45ᵒ and 60ᵒ/45ᵒ/-60ᵒ. This study aimed to determine the effect of fiber angle orientation on tensile strength, maximum deformation and location of maximum stress on carbon fiber composites. The best composite design is the composite with fiber angle orientation of 45ᵒ/90ᵒ/-45ᵒ with a tensile stress value of 3.6 MPa and the smallest deformation of 0.0644 mm.

scholarly journals Finite element analysis of occlusal splint therapy in patients with bruxism

2019 ◽  
Author(s):  
Seifollah Gholampour ◽  
Hanie Gholampour ◽  
Hamed Khanmohammadi
Keyword(s):  
Maximum Stress ◽  
Initial Conditions ◽  
Three Dimensional ◽  
Occlusal Splint ◽  
Element Analysis ◽  
Jaw Bone ◽  
Maximum Deformation ◽  
Splint Therapy ◽  
Control Subjects

Abstract Background: Bruxism is among the habits considered generally as contributory factors for temporomandibular joint (TMJ) disorders and its etiology is still controversial.Methods: Three-dimensional models of maxilla and mandible and teeth of 37 patients and 36 control subjects were created using in-vivo image data. The maximum values of stress and deformation were calculated in 21 patients six months after using a splint and compared with those in the initial conditions. Results: The maximum stresses in the jaw bone and head of mandible were respectively 4.4 and 4.1 times higher in patients than in control subjects. Similar values for deformation were 5.8 and 4.9, respectively. The maximum stress in the jaw bone and head of mandible decreased six months after splint application by up to 71.0% and 72.8%, respectively. Similar values for the maximum deformation were 80.7% and 78.7%, respectively. Following the occlusal splint therapy, the approximation of maximum deformation to the relevant values in control subjects was about 2.6 times the approximation of maximum stress to the relevant values in control subjects. The maximum stress and maximum deformation occurred in all cases in the head of the mandible and the splint had the highest effectiveness in jaw bone adjacent to the molar teeth. Conclusions: Splint acts as a stress relaxer and dissipates the extra stresses generated as well as the TMJ deformation and deviations due to bruxism. The splint also makes the bilateral and simultaneous loading possible and helps with the treatment of this disorder through regulation of bruxism by creating a biomechanical equilibrium between the physiological loading and the generated stress.

Seismic analysis of the rail-counterweight system in elevators considering the stiffness of rail brackets

2020 ◽  
pp. 136943322097477
Author(s):  
Xiaoyan Wang ◽  
Selim Günay ◽  
Wensheng Lu
Keyword(s):  
Maximum Stress ◽  
Seismic Analysis ◽  
Stiffness Ratio ◽  
Continuous Beam ◽  
Seismic Responses ◽  
Maximum Displacement ◽  
Maximum Deformation ◽  
Simply Supported ◽  
System A ◽  
Earthquake Characteristics

The rail in the rail-counterweight system in elevators is vertically supported along the building height by the rail brackets. In the numerical model of the rail-counterweight system, the rail-bracket assembly is modelled as a continuous beam supported by linear springs representing the rail brackets and the stiffness of the bracket is contributed to the overall stiffness of the rail-bracket assembly. To investigate the effect of the rail brackets on the seismic responses of the rail-counterweight system, a parameter named “stiffness ratio” is proposed in a rail-bracket assembly, defined as the ratio of the stiffness of the bracket to that of the simply supported continuous beam representing the rail at mid-span of an intermediate span. The stiffness of the brackets is varied by changing the stiffness ratio of the rail-bracket assembly, and the corresponding seismic responses of the rail-counterweight system are analyzed, including the maximum stress in the rail, the maximum deformation of the brackets, and the maximum displacement of the roller guide off the rail. A comprehensive analysis is conducted by considering four rail spans and three earthquake motions. The variations of the responses with the increasing stiffness ratio are dependent on the earthquake characteristics and the rail spans. The less the rail span is, the less important the effects of the stiffness ratio are. Nevertheless, the seismic responses of the rail-counterweight system generally have little change when the stiffness ratio is up to 4 and more. It is indicated that increasing of the stiffness ratio are not necessarily capable of improving the seismic performance of the counterweight system, especially when the stiffness ratio or the stiffness coefficient of the brackets is large, varying the stiffness ratio is unhelpful to change the rail-counterweight responses.

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