Synthesis of the Base Curves For N-Lobed Elliptical Gears

2004 ◽  
Vol 127 (5) ◽  
pp. 997-1005 ◽  
Author(s):  
Giorgio Figliolini ◽  
Jorge Angeles
Keyword(s):  
Differential Geometry ◽  
Tooth Profile ◽  
Spur Gears ◽  
Profile Angle ◽  
Pressure Angle ◽  
Base Circle ◽  
Noncircular Gears ◽  
The Right ◽  
First Time ◽  
Envelope Theory

Motivated by the need to synthesize the tooth profiles of noncircular gears, we approach the synthesis of the tooth profile of circular spur gears using their pitch circle, rather than their base circle. We do this by means of envelope theory. The proposed formulation gives the involute tooth profile and its well-known base circle for any pitch radius and profile angle of the rack cutter, which coincides with the pressure angle for circular gears. Then, the foregoing approach applies to the synthesis of the base curves of noncircular gears with involute tooth profiles and of their rack. We do this by resorting to basic differential geometry using the Euler–Savary Theorem, rather than to envelope theory. In particular, the formulation of both base curves for the right and left involute tooth profiles is obtained, for the first time, for N-lobed elliptical gears and their rack through the formulation of the pitch curves and their evolutes. The proposed formulation is illustrated with numerical results.

Effects of Drive Side Pressure Angle on Gear Fatigue Crack Propagation Life for Spur Gears With Symmetric and Asymmetric Teeth

2019 ◽  
Author(s):  
Fatih Karpat ◽  
Oguz Dogan ◽  
Tufan Yilmaz ◽  
Celalettin Yuce ◽  
Onur Can Kalay ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Tooth Profile ◽  
Spur Gears ◽  
Pressure Angle ◽  
Side Pressure ◽  
Machine Elements ◽  
Fatigue Crack Propagation Life ◽  
Initial Starting

Abstract Today gears are one of the most crucial machine elements in the industry. They are used in every area of the industry. Due to the high performances of the gears, they are also used in aerospace and wind applications. In these areas due to the high torques, unstable conditions, high impact forces, etc. cracks can be seen on the gear surface. During the service life, these cracks can be propagated and gear damages can be seen due to the initial cracks. The aim of this study is to increase the fatigue crack propagation life of the spur gears by using asymmetric tooth profile. Nowadays asymmetric gears have a very important and huge usage area in the industry. In this study, the effects of drive side pressure angle on the fatigue crack propagation life are studied by using the finite element method. The initial starting points of the cracks are defined by static stress analysis. The starting angles of the cracks are defined constant at 45°. The crack propagation analyses are performed in ANSYS SMART Crack-Growth module by using Paris Law. Four different drive side pressure angles (20°-20°, 20°-25°, 20°-30° and 20°-35°) are investigated in this study. As a result of the study the fatigue crack propagation life of the gears is increased dramatically when the drive side pressure angle increase. This results show that the asymmetric tooth profile not only decrease the bending stress but also increase the fatigue crack propagation life strongly.

A transient contact position prediction method for worn tooth profile under dry running conditions

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Shengnan Zhang ◽  
Z.l. Sun ◽  
Zhenliang Yu ◽  
Fanyi Guo
Keyword(s):  
Surface Profile ◽  
Prediction Method ◽  
Tooth Profile ◽  
Contact Model ◽  
Content Type ◽  
Pressure Angle ◽  
Base Circle ◽  
Position Prediction ◽  
Transient Contact ◽  
Contact Position

Purpose The purpose of this paper is to establish a transient contact position prediction method of gears at the meshing point based on the equivalent contact model. Design/methodology/approach In this method, the contacting surface profiles are constantly updated by changing the pressure angle and the chord tooth thickness, which has a direct connection with the equivalent base circle radius. According to the equivalent base circle radius, the equivalent pressure angle at the pitch circle and equivalent pitch point can be calculated. The equivalent contacting surface profile is determined by the equivalent pressure angle at the pitch circle; for each meshing point, there is one equivalent pressure angle at the pitch circle. Therefore, each meshing point can be regarded as a point on the equivalent contacting surface profile. Findings The model is applicable to find out the contact position after a series of meshing cycles through the law of pressure angle change and intentionally kept as simple as possible with the aim to be used in further study of gear flanks at the point of the actual contact. Practical implications The results of the experiment are applied to the equivalent contact model to describe the transient contact position and assess the model accuracy. Originality/value The determination of the contact position of the worn tooth profile provides the action points of the force for the study of the contact fatigue.

Study of the Base Curve and Formation of Singular Points on the Tooth Profile of Noncircular Gears

2006 ◽  
Vol 129 (5) ◽  
pp. 538-545 ◽  
Author(s):  
Héctor Fabio Quintero Riaza ◽  
Salvador Cardona i Foix ◽  
Lluïsa Jordi Nebot
Keyword(s):  
A Priori ◽  
Tooth Profile ◽  
Singular Points ◽  
Curvature Radius ◽  
Base Curve ◽  
Minimum Number ◽  
Base Circle ◽  
Noncircular Gears ◽  
Gear Wheels ◽  
Pitch Curve

The base circle of a circular gear is concentric with the pitch circle and tangent to the action line. However, in a noncircular gear the base curve is not known a priori and not easy to determine. In this study, the base curves of noncircular gear wheels are obtained as the geometrical locus of the singular points on the involute tooth profile. Singular points—points from which a second involute branch begins to form on the tooth profile—restrict the allowable tooth height and allow the minimum number of teeth required to be estimated. We discuss the influence of the curvature radius of the pitch curve on the allowable tooth height and present an example to illustrate the proposed method.

Feasibility and Evaluation of Automated Methods for Radiolabeling of Radiopharmaceutical Kits with Gallium-68

2019 ◽  
Vol 12 (3) ◽  
pp. 229-237 ◽  
Author(s):  
Alban Revy ◽  
François Hallouard ◽  
Sandrine Joyeux-Klamber ◽  
Andrea Skanjeti ◽  
Catherine Rioufol ◽  
...  
Keyword(s):  
The European Union ◽  
Preparation Time ◽  
Limit Of Quantification ◽  
Manual Method ◽  
Personnel Costs ◽  
Automated Method ◽  
Gallium 68 ◽  
The Right ◽  
First Time ◽  
Automated Methods

Objective: Recent gallium-68 labeled peptides are of increasing interest in PET imaging in nuclear medicine. Somakit TOC® is a radiopharmaceutical kit registered in the European Union for the preparation of [68Ga]Ga-DOTA-TOC used for the diagnosis of neuroendocrine tumors. Development of a labeling process using a synthesizer is particularly interesting for the quality and reproducibility of the final product although only manual processes are described in the Summary of Product (SmPC) of the registered product. The aim of the present study was therefore to evaluate the feasibility and value of using an automated synthesizer for the preparation of [68Ga]Ga-DOTA-TOC according to the SmPC of the Somakit TOC®. Methods: Three methods of preparation were compared; each followed the SmPC of the Somakit TOC®. Over time, overheads, and overexposure were evaluated for each method. Results: Mean±SD preparation time was 26.2±0.3 minutes for the manual method, 28±0.5 minutes for the semi-automated, and 40.3±0.2 minutes for the automated method. Overcost of the semi-automated method is 0.25€ per preparation for consumables and from 0.58€ to 0.92€ for personnel costs according to the operator (respectively, technician or pharmacist). For the automated method, overcost is 70€ for consumables and from 4.06€ to 6.44€ for personnel. For the manual method, extremity exposure was 0.425mSv for the right finger, and 0.350mSv for the left finger; for both the semi-automated and automated method extremity exposure were below the limit of quantification. Conclusion: The present study reports for the first time both the feasibility of using a [68Ga]- radiopharmaceutical kit with a synthesizer and the limits for the development of a fully automated process.

Self-Regulation and Human Progress

2018 ◽  
Author(s):  
Evan Osborne
Keyword(s):  
Scientific Method ◽  
Mutual Influence ◽  
Free Market ◽  
Self Regulation ◽  
Free Expression ◽  
Trial And Error ◽  
Human History ◽  
Economic Context ◽  
The Right ◽  
First Time

Does humanity progress primarily through leaders organizing and directing followers, or through trial and error by individuals free to chart their own path? For most of human history ruling classes had the capacity and the desire to tightly regiment society, to the general detriment of progress. But beginning in the 1500s, Europeans developed a series of arguments for simply leaving well enough alone. First in the form of the scientific method, then in the form of free expression, and finally in the form of the continuously, spontaneously reordered free market, people began to accept that progress is hard, and requires that an immense number of mistakes be tolerated so that we may learn from them. This book tells the story of the development of these three ideas, and for the first time tells of the mutual influence among them. It outlines the rise, and dramatic triumph, of each of these self-regulating systems, followed by a surprising rise in skepticism, especially in the economic context. Such skepticism in the 20th century was frequently costly and sometimes catastrophic. Under the right conditions, which are more frequent than generally believed, self-regulating systems in which participants organize themselves are superior. We should accept their turbulence in exchange for the immense progress they generate.

In the Labyrinth

2017 ◽  
Author(s):  
Andrew McNeillie
Keyword(s):  
The Right ◽  
First Time ◽  
Do So

It is now widely acknowledged, and far beyond Ireland, that Tim Robinson’s two volumes jointly known as Stones of Aran (‘Pilgrimage’ and ‘Labyrinth’) are modern classics, exemplary in every way of how to write about place and to do so with a formal, literary accomplishment that more than earns the right to nod at Ruskin’s own classic. In 2012, Robinson went back to Árainn, the largest of the three islands, for the first time in nearly ten years. He did so at the urging of Andrew McNeillie, with whom he spent two and a half days revisiting old haunts. This chapter makes account of the occasion and uses, in the process, a unique document provided by Robinson as an experiment in annotating his work. This prompts McNeillie to investigate some of his own annotations and footnotes to Aran.

scholarly journals Laparoscopic Resection of Renal Capsular Endometriosis in a Woman with Menstrual-Related Flank Pain: Case Report

2021 ◽  
Vol 27 (1) ◽  
Author(s):  
Abbas Basiri ◽  
Iman Ghanaat ◽  
Hamidreza Akbari Gilani
Keyword(s):  
Flank Pain ◽  
Pathological Examination ◽  
Histologic Evaluation ◽  
Normal Renal Parenchyma ◽  
Perinephric Space ◽  
Superior Portion ◽  
The Right ◽  
First Time ◽  
Laparoscopic Removal

Abstract Background Although involvement of the urinary system is not uncommon, endometriosis in the kidneys is rare. To date, laparoscopic partial nephrectomy has been the preferred approach for managing renal endometriosis. Here, we report for the first time the results of laparoscopic removal of a renal capsular endometriosis in a malrotated kidney in an attempt to save the whole kidney parenchyma, in terms of feasibility and safety. Case presentation A 37-year-old female presented with periodic right flank pain associated with her menstrual cycle. On imaging, a malrotated right kidney and a hypodense irregular-shaped lesion measuring 30 * 20 * 15 mm were seen in the superior portion of the right perinephric space. Histologic evaluation of the ultrasound-guided biopsy was consistent with renal capsular endometriosis. The patient underwent laparoscopic surgery to remove the capsular mass while preserving the normal renal parenchyma. Pathological examination of the biopsy obtained during surgery was in favor of renal endometriosis. At 6-month follow-up, the patient’s pain had completely disappeared and no complications had occurred. In addition, imaging did not show any remarkable recurrence. Conclusion Renal endometriosis should be strongly considered as a differential diagnosis in female patients with a renal capsular mass and exacerbation of flank pain during menstruation. Based on our experience, with preoperative needle biopsy and clearing the pathology, laparoscopic removal of the mass in spite of renal anatomic abnormality is feasible and safe and thus could be considered as a possible treatment option.

Ankle Arthritis Networking: Getting the right treatment to the right patient first time

2021 ◽  
Author(s):  
Stephen Bendall ◽  
Paul Halliwell ◽  
Andrew Goldberg ◽  
Andrew Robinson
Keyword(s):  
Ankle Arthritis ◽  
The Right ◽  
First Time
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