A Method of Local Synthesis of Gears Grounded on the Connections Between the Principal and Geodetic Curvatures of Surfaces

1981 ◽  
Vol 103 (1) ◽  
pp. 114-122 ◽  
Author(s):  
F. L. Litvin ◽  
Y. Gutman
Keyword(s):  
Contact Point ◽  
Optimal Conditions ◽  
Principal Curvatures ◽  
Local Synthesis ◽  
Double Curvature ◽  
Tooth Surfaces ◽  
Gear Mechanism ◽  
The Relationship

A spatial gear-mechanism with double curvature tooth surfaces is discussed. The following results are obtained: a) the relationship between the principal curvatures of the surfaces, b) the conditions under which the path of the contact point on the surface is a geodetic line in the local sense. A method of synthesis of mismatched gearing proposed here permits determination of optimal conditions of meshing in the vicinity of the main contact point.

Determination of Principal Curvatures and Contact Ellipse for Profile Crowned Helical Gears

1999 ◽  
Vol 121 (1) ◽  
pp. 107-111 ◽  
Author(s):  
P.-H. Feng ◽  
F. L Litvin ◽  
D. P. Townsend ◽  
R. F. Handschuh
Keyword(s):  
Gear Tooth ◽  
Principal Curvatures ◽  
Helical Gears ◽  
Bearing Contact ◽  
Pinion Gear ◽  
Straight Line ◽  
Tooth Surfaces ◽  
Simplified Solution ◽  
Contact Ellipse

Helical gears with localized bearing contact of tooth surfaces achieved by profile crowning of tooth surfaces are considered. Profile crowning is provided by application of two imaginary rack-cutters with mismatched surfaces. The goal is to determine the dimensions and orientation of the instantaneous contact ellipse that requires the determination of principle curvatures of pinion-gear tooth surfaces. A simplified solution to this problem is proposed based on the approach developed in [1, 2] for correlation of principal curvatures and directions of generating and generated tooth surfaces. The obtained equations are applied for profile crowning where the normal profiles of the rack-cutters are either a circular arc or a straight line.

Application of Finite Element Analysis for Determination of Load Share, Real Contact Ratio, Precision of Motion, and Stress Analysis

1996 ◽  
Vol 118 (4) ◽  
pp. 561-567 ◽  
Author(s):  
F. L. Litvin ◽  
J.-S. Chen ◽  
J. Lu ◽  
R. F. Handschuh
Keyword(s):  
Finite Element ◽  
Stress Analysis ◽  
Point Contact ◽  
Principal Curvatures ◽  
Contact Ratio ◽  
Element Analysis ◽  
Transmission Errors ◽  
Real Contact ◽  
Tooth Surfaces

A loaded gear drive with point contact between tooth surfaces is considered. The principal curvatures and directions at a current point of tangency, the contact paths on tooth surfaces, and the transmission errors caused by misalignment we consider as known. In this paper the following topics are covered: (1) Determination of the contact force and its distribution over the contact ellipse; (2) Determination of the tooth deflection, the load share, and the real contact ratio; and (3) Stress analysis by application of the finite element method. The discussed approach is illustrated with a numerical example.

Determination of Formaldehyde Based on the Fading Reaction of Bordeaux R by Flow Injection Spectrophotometry

2012 ◽  
Vol 610-613 ◽  
pp. 436-439
Author(s):  
Ling Su ◽  
Wei Wei ◽  
Jia Liang Guo ◽  
Zhen Liu ◽  
Lu Sheng Liu
Keyword(s):  
Flow Injection ◽  
Optimal Conditions ◽  
Affecting Factors ◽  
Sulfuric Acid Medium ◽  
Relative Standard ◽  
Relationship Of ◽  
The Relationship ◽  
Catalytic Effects ◽  
Coexisting Ions

A method for determination of formaldehyde by flow injection spectrophotometry based on the catalytic effects of formaldehyde on the oxidation reaction of Bordeaux R by potassium chlorate in sulfuric acid medium was established. The relationship of the reduced absorbency to the concentration of formaldehyde was good linearity and the maximum absorption peak located at 520nm. The affecting factors on the strength of absorption including acidity, dosage, temperature, coexisting ions and so on, and the optimal conditions of the reaction in the system were investigated. Calibration graphs were linear for ranges of 0 to 3.0 mg l−1 and a detection limit of 2×10-8 g ml−1 formaldehyde was achieved. The proposed method was successfully applied to the analyses of environmental samples, with relative standard deviation of less than 1.6% and the recoveries are 93.6 % to 94.5% for the determination of formaldehyde.

Differential Geometrical Conditions of Hypoid Gears with Conjugate Tooth Surfaces

1998 ◽  
Vol 122 (3) ◽  
pp. 323-330 ◽  
Author(s):  
Norio Ito ◽  
Koichi Takahashi
Keyword(s):  
Contact Line ◽  
Necessary Conditions ◽  
Contact Point ◽  
Theoretical Solution ◽  
Curved Surfaces ◽  
Principal Curvatures ◽  
Hypoid Gears ◽  
Tooth Surfaces ◽  
Principal Directions

Hypoid gears are one of the most general form of gearing, and a theoretical solution for them has been studied by many researchers. Many hypotheses and theorems about these gears have been proposed—some of them correct and many of them wrong. The tooth surfaces are parts of general curved surfaces and they must have principal directions and principal curvatures on every contact point. However, there has been no detailed research on the fundamental elements of the surface. This study develops necessary conditions for determining these curvatures and principal directions for conjugate gearing with a contact line by introducing the concept of geodesic torsions. [S1050-0472(00)00503-1]

Thromboplastin Related Differences in the Determination of International Normalised Ratio: A Cause for Concern?

1994 ◽  
Vol 72 (03) ◽  
pp. 426-429 ◽  
Author(s):  
S Kitchen ◽  
I D Walker ◽  
T A L Woods ◽  
F E Preston
Keyword(s):  
Patient Management ◽  
External Quality Assessment ◽  
Oral Anticoagulant Therapy ◽  
Warfarin Dosage ◽  
External Quality ◽  
External Quality Assessment Scheme ◽  
International Normalised Ratio ◽  
The Uk ◽  
The Relationship

SummaryWhen the International Normalised Ratio (INR) is used for control of oral anticoagulant therapy the same result should be obtained irrespective of the laboratory reagent used. However, in the UK National External Quality Assessment Scheme (NEQAS) for Blood Coagulation INRs determined using different reagents have been significantly different.For 18 NEQAS samples Manchester Reagent (MR) was associated with significantly lower INRs than those obtained using Diagen Activated (DA, p = 0.0004) or Instrumentation Laboratory PT-Fib HS (IL, p = 0.0001). Mean INRs for this group were 3.15, 3.61, and 3.65 for MR, DA, and IL respectively. For 61 fresh samples from warfarin-ised patients with INRs of greater than 3.0 the relationship between thromboplastins in respect of INR was similar to that observed for NEQAS data. Thus INRs obtained with MR were significantly lower than with DA or IL (p <0.0001). Mean INRs for this group were 4.01, 4.40, and 4.59 for MR, DA, and IL respectively.We conclude that the differences between INRs measured with the thromboplastins studied here are sufficiently great to influence patient management through warfarin dosage schedules, particularly in the upper therapeutic range of INR. There is clearly a need to address the issues responsible for the observed discrepancies.

Modern determinants of endometrium hyperplastic processes pathogenesis

2016 ◽  
pp. 137-142
Author(s):  
V.O. Benyuk ◽  
◽  
V.M. Goncharenko ◽  
T.R. Nykoniuk ◽  
◽  
...  
Keyword(s):  
Conservative Therapy ◽  
Solid Phase ◽  
Research Direction ◽  
Immunohistochemical Method ◽  
Results Of Treatment ◽  
Treatment And Prevention ◽  
Receptor Phenotype ◽  
The Relationship ◽  
Endometrial Proliferation

The objective: to еxplore the relationship between the activity of endometrial proliferation and the state of the local immune response in the uterus in the conditions berprestasi process. Patients and methods. Examined 228 women of reproductive and perimenopausal age with endometrial pathology using ultrasound and then performing hysteroresectoscopy. Determination of the concentrations of the cytokines IL-1, IL-2, IL-6 and TNF was performed by solid phase ELISA. Results. Found a trend that confirms the loss of sensitivity to hormones at the stage of malignancy of the endometrium and can be used as diagnostic determinants in determining the nature of intrauterine pathology and criterion of the effectiveness of conservative therapy. Conclusion. Improving etiopatogenetice approach to the therapy of hyperplastic proce.sses of endometrium with determination of receptor phenotype of the endometrium is a research direction in modern gynecology, which will help to improve the results of treatment and prevention of intrauterine pathology. Key words: endometrial hyperplasia,the receptors for progesterone and estrogen, immunohistochemical method.

Calculating the aerodynamics of vertical axis wind turbines

2012 ◽  
Vol 34 (3) ◽  
pp. 169-184 ◽  
Author(s):  
Hoang Thi Bich Ngoc
Keyword(s):  
Wind Turbine ◽  
Incidence Angle ◽  
Vertical Axis ◽  
Rotor Blades ◽  
Vertical Axis Wind Turbine ◽  
Horizontal Axis Wind Turbine ◽  
Velocity Triangle ◽  
Relationship Of ◽  
The Relationship

Vertical axis wind turbine technology has been applied last years, very long after horizontal axis wind turbine technology. Aerodynamic problems of vertical axis wind machines are discussible. An important problem is the determination of the incidence law in the interaction between wind and rotor blades. The focus of the work is to establish equations of the incidence depending on the blade azimuth, and to solve them. From these results, aerodynamic torques and power can be calculated. The incidence angle is a parameter of velocity triangle, and both the factors depend not only on the blade azimuth but also on the ratio of rotational speed and horizontal speed. The built computational program allows theoretically selecting the relationship of geometric parameters of wind turbine in accordance with requirements on power, wind speed and installation conditions.

Tire Treadwear — A Comprehensive Evaluation of the Factors: Generic Type, Aspect Ratio, Tread Pattern, and Tread Composition Part I: Introduction and Details on the Organization of the Program

1986 ◽  
Vol 14 (4) ◽  
pp. 201-218 ◽  
Author(s):  
A. G. Veith
Keyword(s):  
Aspect Ratio ◽  
Comprehensive Evaluation ◽  
Test Method ◽  
Interactive Effects ◽  
Data Analyses ◽  
Main Effect ◽  
Systematic Determination ◽  
Relationship Of ◽  
The Relationship

Abstract This four-part series of papers addresses the problem of systematic determination of the influence of several tire factors on tire treadwear. Both the main effect of each factor and some of their interactive effects are included. The program was also structured to evaluate the influence of some external-to-tire conditions on the relationship of tire factors to treadwear. Part I describes the experimental design used to evaluate the effects on treadwear of generic tire type, aspect ratio, tread pattern (groove or void level), type of pattern (straight rib or block), and tread compound. Construction procedures and precautions used to obtain a valid and functional test method are included. Two guiding principles to be used in the data analyses of Parts II and III are discussed. These are the fractional groove and void concept, to characterize tread pattern geometry, and a demonstration of the equivalence of wear rate for identical compounds on whole tread or multi-section tread tires.

The Awareness Level of the Safety and Health of the Operational Level

2017 ◽  
Vol 3 (1) ◽  
pp. 42
Author(s):  
Roshanira Che Mohd Noor ◽  
Nur Atiqah Rochin Demong
Keyword(s):  
Health And Safety ◽  
Health Conditions ◽  
Effective Strategies ◽  
Operational Level ◽  
Safety And Health ◽  
Health Factors ◽  
The Cost ◽  
The Relationship ◽  
Awareness Level

Providing a safe and healthy workplace is one of the most effective strategies in for holding down the cost of doing construction business. It was a part of the overall management system to facilitate themanagement of the occupational health and safety risk that are associated with the business of the organization. Factors affected the awareness level inclusive of safety and health conditions, dangerous working area, long wait care and services and lack of emergency communication werethe contributed factors to the awareness level for the operational level. Total of 122 incidents happened at Telekom Malaysia Berhad as compared to year 2015 only 86 cases. Thus, the main objective of this study was to determine the relationship between safety and health factors and the awareness level among operational workers.The determination of this research was to increase the awareness level among the operational level workerswho committing to safety and health environment.

DETERMINATION OF P53 GENE CODON 72 POLYMORPHISMS IN PATIENTS WITH GASTRIC CANCER

2013 ◽  
pp. 11-17
Author(s):  
Thi Tuy Ha Nguyen ◽  
Thi Minh Thi Ha
Keyword(s):  
Gastric Cancer ◽  
Cancer Patients ◽  
P53 Gene ◽  
Diffuse Gastric Cancer ◽  
Codon 72 ◽  
Cancer Group ◽  
Pcr Rflp ◽  
Gastric Cancer Patients ◽  
The Relationship

Background: The role of p53 gene in the gastric cancer is still controversial. This study is aimed at determining the rate of the p53 gene codon 72 polymorphisms in gastric cancer patients and evaluating the relationship between these polymorphisms and endoscopic and histopathological features of gastric cancer. Patients and methods: Sixty eight patients with gastric cancer (cases) and one hundred and thirty six patients without gastric cancer (controls) were enrolled. p53 gene codon 72 polymorphisms were determined by PCR-RFLP technique with DNA extracted from samples of gastric tissue. Results: In the group of gastric cancer, Arginine/Argnine, Arginine/Proline and Proline/Proline genotypes were found in 29.4%, 42.7% and 27.9%, respectively. The differences of rates were not statistically significant between cases and controls (p > 0,05). In males, the Proline/Proline genotype was found in 38.1% in patients with gastric cancer and more frequent in patients without gastric cancer (15.7%, p = 0,01). An analysis of ROC curve showed that the cut-off was the age of 52 in the Proline/Proline genotype, but it was 65 years old in the Arginine/Proline genotype. The Proline/Proline genotype was found in 41.9% in Borrmann III/IV gastric cancer, this rate was higher than Borrmann I/II gastric cancer (16.2%, p = 0.037) and also higher than controls (18.4%, p = 0,01). The rate of Proline/Proline genotype was 41.7% in the diffuse gastric cancer, it was higher than in controls (p = 0,023). Conclusion: No significative difference of rate was found in genotypes between gastric cancer group and controls. However, there was the relationship between Proline/Proline genotype and gastric cancer in males, Borrmann types of gastric cancer, the diffuse gastric cancer. Key words: polymorphism, codon 72, p53 gene, PCR - RFLP, gastric cancer.

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