scholarly journals Microstructural and mechanical studies of feedstock material in continuous extrusion process

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Tariku Desta ◽  
Devendra Kumar Sinha ◽  
Perumalla Janaki Ramulu ◽  
Habtamu Beri Tufa
Keyword(s):  
Yield Strength ◽  
Statistical Significance ◽  
Extrusion Process ◽  
Wheel Speed ◽  
Forming Process ◽  
Percentage Elongation ◽  
Continuous Forming ◽  
Before And After ◽  
Continuous Extrusion ◽  
Feedstock Material

AbstractThe challenge encountered in continuous forming process is the variation in mechanical strength of product formed with respect to process variables like extrusion wheel speed and diameter of product. In this research article, the micro-structural investigation of the aluminum (AA1100) feedstock material of 9.5-mm diameter has been carried out at various extrusion wheel speeds and diameter of product before and after deformation on commercial continuous extrusion setup TBJ350. The mechanical properties like yield strength as well as percentage elongation have been estimated and optimized using two variables with 3 levels through central composite rotatable design (CCRD) method. The mathematical modeling has been carried out to predict the optimum combination of process parameters for obtaining maximum value of yield strength and percentage elongation. The statistical significance of mathematical model is verified through analysis of variance (ANOVA). The optimum value of yield strength is found to be 70.939 MPa at wheel velocity of 8.63 rpm and product diameter of 9 mm respectively, whereas the maximum percentage elongation recorded is 46.457 at wheel velocity of 7.06 rpm and product diameter of 7.18 mm. The outcome may be useful in obtaining the best parametric combination of wheel speed and extrusion ratio for best strength of the product.

Numerical Simulation of the Effect of Feedstock Shape on Continuous Extrusion Process

2012 ◽  
Vol 472-475 ◽  
pp. 2004-2008 ◽  
Author(s):  
Li Chen ◽  
Bao Yun Song ◽  
Xin Bing Yun
Keyword(s):  
Metal Flow ◽  
Flow Characteristics ◽  
Extrusion Process ◽  
Forming Process ◽  
Section Shape ◽  
Wheel Torque ◽  
Metal Deformation ◽  
Continuous Extrusion ◽  
Extrusion Forming ◽  
3D Software

Since the appearance of the continuous extrusion process, the section shape of the feedstock is round. The shape of the feedstock directly affects metal deformation and metal flow characteristics during the continuous extrusion process. Based on finite element method (FEM), using the Deform-3D software, this paper simulates continuous extrusion forming process for copper bus bar, and analyzes the effect of different feedstock shape on metal flowing temperature, velocity, rotating torque. The results show that: the size of the rectangular feedstock must be within a reasonable range, otherwise the continuous extrusion process can not be established; the rectangular feedstock is benefit to the flow uniformity comparing with the round feedstock; the temperature of the billet and tooling with rectangular feedstock is lower than that with round feedstock, as the feedstock width increases, the temperature decreases and the area of high temperature becomes smaller; the change of the feedstock shape and size has no effect on the extrusion wheel torque value.

Theoretical and Experimental Study of the Conform Metal Forming Process

1979 ◽  
Vol 101 (2) ◽  
pp. 116-120 ◽  
Author(s):  
J. Tirosh ◽  
G. Grossman ◽  
G. Gordon
Keyword(s):  
Experimental Study ◽  
Experimental Investigation ◽  
Satisfactory Agreement ◽  
Metal Forming ◽  
Extrusion Process ◽  
Optimal Conditions ◽  
Forming Process ◽  
Metal Forming Process ◽  
Continuous Extrusion ◽  
Conform Process

An analytical and experimental investigation of a new continuous extrusion process (the “Conform Process”) is presented. The extruding force in this process is provided by frictional shear generated by a rotating wheel against which the workpiece is pressed. Expressions are derived for predicting the pressing force and driving power required to extrude continuously a workpiece of unlimited length under optimal conditions. The analysis is substantiated by experiments with satisfactory agreement.

STUDY CLINICAL FEATURE AND RESULT OF TREATMENT PHACOMORPHIC GLAUCOMA

2015 ◽  
pp. 71-75
Author(s):  
Van Nam Phan ◽  
Ba Ken Tran
Keyword(s):  
Visual Acuity ◽  
Intraocular Pressure ◽  
Statistical Significance ◽  
Corneal Edema ◽  
Clinical Feature ◽  
Anterior Chamber Angle ◽  
Male Population ◽  
Significant Difference ◽  
Operative Complications ◽  
Before And After

Purpose: Study clinical feature of phacomorphic glaucoma. To evaluate the result of treatment phacomorphic glaucoma. Method: The retrospective, interventional study on 36 cases with phacomorphic glaucoma who underwent treated at Hue Central Hospital from 6/2010 to 6/2011. Standard of research: visual, IOP, before and after surgery, accompanying lesions and post-operative complications. The surgery is considered successful when postoperative IOP less than 21 mmHg. Results: Age 50-59 presented 30.5 percent, ≥ 60 presented 91.7 percent. There was a slight female preponderance (66.7%) compared to the male population (33.3%) which implies a statistically marginally significant difference. However there was no statistical significance difference when compared by the two subgroups. Patient in country presented 61,1% and city presented 38,9%. The duration between the onset of pain and surgery from 0 to < 5 days (77.8%), from 6 to 10 (16.7%) and >10 days presented 5.5%. The preoperative intraocular pressure 35 to 45mmHg (47.2%), 46-55 (30.6%), 56-65 (13.9%) and more than 65 presented 8.3%. The visual acuity preoperation less than 1metre count finger (94.5%), less than 3 metre count finger presented 5.5%. Close anterior chamber angle presented 80.6% and shallow was presented 19.4%. Corneal edema presented 100%, iritis presented 94.4%, dilated pupil larger 5mm presented 83.3%, Synchynea iris and cataract presented 72.2%. ECCE, implantation IOL combined trabeculectomy presented 11.1%, Phaco, implantation IOL combined trabeculectomy presented 69,5%, ECCE implantation IOL presented 5.6%, Phaco, implantation IOL presented 13.8%. Postoperative visual acuity from 1/10 to 5/10 presented 72.2%, no case have VA larger than 5/10. Postoperative 3 months VA 1/10 to 5/10 presented 72.2%, larger VA 5/10 presented 8.3%. Postoperative 3 months intraocular pressure ≤ 21mmHg presented 91.7%, 22 to 24mmHg presented 8.3%, no case have IOP ≥25mmHg. Postoperative edema presented 58.3%, iritis presented 58.3%. Key words: phacomorphic Glaucoma

scholarly journals Treatment of HIV-associated facial lipoatrophy: impact on infection progression assessed by viral load and CD4 count

2013 ◽  
Vol 88 (4) ◽  
pp. 570-577 ◽  
Author(s):  
Flávia Machado Gonçalves Soares ◽  
Izelda Maria Carvalho Costa
Keyword(s):  
Viral Load ◽  
Disease Progression ◽  
Statistical Significance ◽  
Undetectable Viral Load ◽  
Fat Distribution ◽  
Cd4 Count ◽  
Before And After ◽  
Facial Lipoatrophy ◽  
A Prospective Study ◽  
The Impact

BACKGROUND: HIV/AIDS-Associated Lipodystrophy Syndrome includes changes in body fat distribution, with or without metabolic changes. The loss of fat from the face, called facial lipoatrophy, is one of the most stigmatizing signs of the syndrome.OBJECTIVES:To evaluate the effect of FL treatment using polymethylmethacrylate (PMMA) implants on disease progression, assessed by viral load and CD4 cell count.METHODS: This was a prospective study of 44 patients treated from July 2009 to December 2010. Male and female patients, aged over 18 years, with clinically detectable FL and who had never been treated were included in the study. PMMA implantation was done to fill atrophic areas. Laboratory tests were conducted to measure viral load and CD4 count before and after treatment.RESULTS: Of the 44 patients, 72.72% were male and 27.27% female, mean age of 44.38 years. Before treatment, 82% of patients had undetectable viral load, which increased to 88.6% after treatment, but without statistical significance (p = 0.67). CD4 count before treatment ranged from 209 to 1293, averaging 493.97. After treatment, the average increased to 548.61. The increase in CD4 count after treatment was statistically significant with p = 0.02.CONCLUSION: The treatment of FL with PMMA implants showed a statistically significant increase in CD4 count after treatment, revealing the impact of FL treatment on disease progression. Viral load before and after treatment did not vary significantly.

scholarly journals Process chain for the manufacture of hybrid bearing bushings

2021 ◽  
Vol 15 (2) ◽  
pp. 137-150
Author(s):  
Susanne Elisabeth Thürer ◽  
Anna Chugreeva ◽  
Norman Heimes ◽  
Johanna Uhe ◽  
Bernd-Arno Behrens ◽  
...  
Keyword(s):  
Extrusion Process ◽  
Steel Tube ◽  
Case Hardening ◽  
Process Chain ◽  
Forming Process ◽  
Die Forging ◽  
Material Contact ◽  
Hybrid Bearing ◽  
Case Hardening Steel ◽  
Tailored Forming

AbstractThe current study presents a novel Tailored Forming process chain developed for the production of hybrid bearing bushings. In a first step, semi-finished products in the form of locally reinforced hollow profiles were produced using a new co-extrusion process. For this purpose, a modular tool concept was developed in which a steel tube made of a case-hardening steel, either C15 (AISI 1015) or 20MnCr5 (AISI 5120), is fed laterally into the tool. Inside the welding chamber, the steel tube is joined with the extruded aluminum alloy EN AW-6082. In the second step, sections from the compound profiles were formed into hybrid bearing bushings by die forging. In order to set the required forming temperatures for each material—aluminum and steel—simultaneously, a tailored heating strategy was developed, which enabled successful die forging of the hybrid workpiece to the desired bearing bushing geometry. Using either of the case-hardening steels in combination with aluminum, this novel process chain made it possible to produce intact hybrid bearing bushings, which showed both macroscopically and microscopically intimate material contact inside the compound zone.

The effect of mask use on maternal oxygen saturation in term pregnancies during the COVID-19 process

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Erzat Toprak ◽  
Ayça Nazlı Bulut
Keyword(s):  
Oxygen Saturation ◽  
Pregnant Women ◽  
Stress Test ◽  
Statistical Significance ◽  
Categorical Variables ◽  
Fisher Exact Test ◽  
Coin Toss ◽  
Arterial Blood ◽  
Surgical Masks ◽  
Before And After

AbstractObjectivesOur aim was to evaluate the effect of standard surgical and N-95 respiratory mask use on maternal oxygen saturation, vital signs and result on non-stress tests in term pregnancies.MethodsIt is a prospective observational study. The study included healthy, not in labor, singleton pregnant women of 370/7–410/7 weeks who were applied to our hospital for routine obstetric control examination between March 1, 2020, and August 31, 2020. Patients were randomised by coin toss method. Oxygen saturation, systolic, and diastolic arterial blood pressure, pulse, respiratory rate, and temperature of pregnant women using surgical masks and respiratory masks were measured before and after the non-stress test. The tolerance of the masks was also evaluated. Student’s t-test was used for variables showing parametric distribution and the Mann Whitney U-test was used for non-parametric tests. The categorical variables between the groups was analyzed by using the Chi square test or Fisher Exact test. The statistical significance level was taken as p<0.05 in all tests.ResultsA total of 297 pregnant women using masks were included in the study. The effect of mask type on oxygen saturation before and after the non-stress test was found to be significant (97.1±1.8 corresponds to 95.3±2.6 for the surgical mask, p=0.0001; 97.8±1.7 corresponds to 93.7±2.0 for the respiratory mask, p=0.0001). Mask tolerance of patients using respiratory masks was significantly higher than those using surgical masks (mean 8, 1–10, p=0.0001).ConclusionsSurgical mask and respiratory mask usage decreased significantly in oxygen saturation in term pregnancies.

scholarly journals Gamma entrainment frequency affects mood, memory and cognition: an exploratory pilot study

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Ryan L. S. Sharpe ◽  
Mufti Mahmud ◽  
M. Shamim Kaiser ◽  
Jianhui Chen
Keyword(s):  
Pilot Study ◽  
Correlation Analysis ◽  
Negative Correlation ◽  
Cognitive Abilities ◽  
Statistical Significance ◽  
Assessment Scores ◽  
Frequency Group ◽  
Before And After ◽  
Mood Score ◽  
40 Hz

AbstractHere we provide evidence with an exploratory pilot study that through the use of a Gamma 40 Hz entrainment frequency, mood, memory and cognition can be improved with respect to a 9-participant cohort. Participants constituted towards three binaural entrainment frequency groups: the 40 Hz, 25 Hz and 100 Hz. Participants attended a total of eight entrainment frequency sessions twice over the duration of a 4-week period. Additionally, participants were assessed based on their cognitive abilities, mood as well as memory, where the cognitive and memory assessments occurred before and after a 5-min binaural beat stimulation. The mood assessment scores were collected from sessions 1, 4 and 8, respectively. With respect to the Gamma 40 Hz entrainment frequency population, we observed a mean improvement in cognitive scores, elevating from 75% average to 85% average upon conclusion of the experimentation at weak statistical significance ($$\alpha$$ α = 0.10, p = 0.076). Similarly, memory score improvements at a greater significance ($$\alpha$$ α = 0.05, p = 0.0027) were noted, elevating from an average of 87% to 95%. In pertinence to the mood scores, a negative correlation across all populations were noted, inferring an overall increase in mood due to lower scores correlating with elevated mood. Finally, correlation analysis revealed a stronger R$$^2$$ 2 value (0.9838) within the 40 Hz group between sessions as well as mood score when compared across the entire frequency group cohort.

Interfaces in Multiphase Polymers and Nanomedicines

2012 ◽  
Vol 714 ◽  
pp. 211-215 ◽  
Author(s):  
Gergo Patyi ◽  
Zsombor Nagy ◽  
Balazs Vajna ◽  
Peter Anna ◽  
Gyorgy Marosi
Keyword(s):  
Extrusion Process ◽  
Structural Features ◽  
Continuous Extrusion ◽  
Multiphase Composite

Crystalline and amorphous interfaces were formed and modified in multiphase composite and pharmaceutical systems. Nanosize drug of antacid effect was prepared in continuous extrusion process. The structural features were analyzed using (micro-) thermal analytical and (micro-) Raman spectrometric methods combined with chemometric evaluation.

scholarly journals Bone Cement Solidifiliation Influence the Limb Alignment and Gap Balance during TKA

2015 ◽  
Vol 2015 ◽  
pp. 1-3 ◽  
Author(s):  
Dongquan Shi ◽  
Xingquan Xu ◽  
Anyun Guo ◽  
Jin Dai ◽  
Zhihong Xu ◽  
...  
Keyword(s):  
Total Knee Arthroplasty ◽  
Bone Cement ◽  
Knee Arthroplasty ◽  
Mechanical Axis ◽  
Statistical Significance ◽  
Mechanical Alignment ◽  
Early Loosening ◽  
Flexion Extension ◽  
Before And After ◽  
Total Knee

Introduction. Mechanical alignment deviation after total knee arthroplasty is a major reason for early loosening of the prosthesis. Achieving optimum cement penetration during fixation of the femoral and tibial component is an essential step in performing a successful total knee arthroplasty. Bone cement is used to solidify the bone and prosthesis. Thickness imbalance of bone cement leads to the deviation of mechanical alignment. To estimate the influence of bone cement, a retrospective study was conducted.Materials and Methods. A total of 36 subjects were studied. All the TKA were performed following the standard surgical protocol for navigated surgery by medial approach with general anaesthesia. Prostheses were fixed by bone cement.Results. We compared the mechanical axis, flexion/extension, and gap balance before and after cementation. All the factors were different compared with those before and after cementation. Internal rotation was reached with statistical significance (P=0.03).Conclusion. Bone cement can influence the mechanical axis, flexion/extension, and gap balance. It also can prompt us to make a change when poor knee kinematics were detected before cementation.

Sign in / Sign up

Export Citation Format

Share Document