Effects of the center distance setting error on the helix error of a planar enveloping hourglass worm

2016 ◽  
pp. 1049-1054
Author(s):  
Fayang He ◽  
Zhaoyao Shi ◽  
Bo Yu
Keyword(s):  
Setting Error ◽  
Center Distance ◽  
Distance Setting

Effect of Contact Ratio on Spur Gear Dynamic Load With No Tooth Profile Modifications

1996 ◽  
Vol 118 (3) ◽  
pp. 439-443 ◽  
Author(s):  
Chuen-Huei Liou ◽  
Hsiang Hsi Lin ◽  
F. B. Oswald ◽  
D. P. Townsend
Keyword(s):  
Dynamic Load ◽  
Spur Gear ◽  
Tooth Size ◽  
Contact Ratio ◽  
Gear Dynamics ◽  
Wide Range ◽  
Gear Contact ◽  
Center Distance ◽  
Selection Of ◽  
Better Than

This paper presents a computer simulation showing how the gear contact ratio affects the dynamic load on a spur gear transmission. The contact ratio can be affected by the tooth addendum, the pressure angle, the tooth size (diametral pitch), and the center distance. The analysis presented in this paper was performed by using the NASA gear dynamics code DANST. In the analysis, the contact ratio was varied over the range 1.20 to 2.40 by changing the length of the tooth addendum. In order to simplify the analysis, other parameters related to contact ratio were held constant. The contact ratio was found to have a significant influence on gear dynamics. Over a wide range of operating speeds, a contact ratio close to 2.0 minimized dynamic load. For low-contact-ratio gears (contact ratio less than two), increasing the contact ratio reduced gear dynamic load. For high-contact-ratio gears (contact ratio equal to or greater than 2.0), the selection of contact ratio should take into consideration the intended operating speeds. In general, high-contact-ratio gears minimized dynamic load better than low-contact-ratio gears.

scholarly journals A multivariate intersection over union of SiamRPN network for visual tracking

2021 ◽  
Author(s):  
Zhihui Huang ◽  
Huimin Zhao ◽  
Jin Zhan ◽  
Huakang Li
Keyword(s):  
Aspect Ratio ◽  
Visual Tracking ◽  
Target Location ◽  
Coincidence Degree ◽  
Distance Ratio ◽  
Geometric Factors ◽  
Fast Motion ◽  
Definition Of ◽  
Overlap Area ◽  
Center Distance

AbstractSiamPRN algorithm performs well in visual tracking, but it is easy to drift under occlusion and fast motion scenes because it uses $$\ell _1$$ ℓ 1 -smooth loss function to measure the regression location of bounding box. In this paper, we propose a multivariate intersection over union (MIOU) loss in SiamRPN tracking framework. Firstly, MIOU loss includes three geometric factors in regression: the overlap area ratio, the center distance ratio, and the aspect ratio, which can better reflect the coincidence degree of target box and prediction box. Secondly, we improve the definition of aspect ratio loss to avoid gradient explosion, improve the optimization performance of prediction box. Finally, based on SiamPRN tracker, we compared the tracking performance of $$\ell _1$$ ℓ 1 -smooth loss, IOU loss, GIOU loss, DIOU loss, and MIOU loss. Experimental results show that the MIOU loss has better target location regression than other loss functions on the OTB2015 and VOT2016 benchmark, especially for the challenges of occlusion, illumination change and fast motion.

scholarly journals Myopia Control with Combination Low-Dose Atropine and Peripheral Defocus Soft Contact Lenses: A Case Series

2021 ◽  
pp. 548-554
Author(s):  
Nir Erdinest ◽  
Naomi London ◽  
Nadav Levinger ◽  
Yair Morad
Keyword(s):  
Low Dose ◽  
Contact Lenses ◽  
Case Series ◽  
Concentric Circle ◽  
Retrospective Case ◽  
Soft Contact ◽  
Myopia Progression ◽  
Soft Contact Lenses ◽  
Center Distance ◽  
Myopia Control

The goal of this retrospective case series is to demonstrate the effectivity of combination low-dose atropine therapy with peripheral defocus, double concentric circle design with a center distance soft contact lenses at controlling myopia progression over 1 year of treatment. Included in this series are 3 female children aged 8–10 years with progressing myopia averaging −4.37 ± 0.88 D at the beginning of treatment. Their average annual myopic progression during the 3 years prior to therapy was 1.12 ± 0.75 D. They had not attempted any myopia control treatments prior to this therapy. The children were treated with a combination of 0.01% atropine therapy with spherical peripheral defocus daily replacement soft lenses MiSight<sup>®</sup> 1 day (Cooper Vision, Phoenix, AZ, USA). They underwent cycloplegic refraction, and a slit-lamp evaluation every 6 months which confirmed no adverse reactions or staining was present. Each of the 3 children exhibited an average of 0.25 ± 0.25 D of myopia progression at the end of 1 year of treatment. To the best of the authors’ knowledge, this is the first published study exhibiting that combining low-dose atropine and peripheral defocus soft contact lenses is effective at controlling children’s moderate to severe myopia progression during 1 year of therapy.

Artifact Design and Measurement Error Analysis in the Evaluation of Lead Measurement Accuracy of Helical Gear Using Wedge Artifact

2010 ◽  
Vol 132 (7) ◽  
Author(s):  
Masaharu Komori ◽  
Fumi Takeoka ◽  
Aizoh Kubo ◽  
Kazuhiko Okamoto ◽  
Sonko Osawa ◽  
...  
Keyword(s):  
Evaluation Method ◽  
Plane Surface ◽  
Design Method ◽  
Measuring Instrument ◽  
Setting Error ◽  
Geometrical Form ◽  
Measurement Experiment ◽  
Mechanical Devices ◽  
Tooth Flank ◽  
Artifact Design

The reduction in the vibration and noise of gears is an important issue in mechanical devices such as vehicles and wind turbines. The characteristics of the vibration and noise of gears are markedly affected by deviations of the tooth flank form of micrometer order; therefore, strict quality control of the tooth flank form is required. The accuracy of the lead measurement for a gear-measuring instrument is usually evaluated using a helicoid artifact. However, it is difficult to manufacture it with high accuracy because the helix is a complicated geometrical form. To solve this problem, a method of evaluating a gear-measuring instrument using a wedge artifact, which includes a highly precise plane surface, has been proposed. In this research, to put the wedge artifact into practice, a design method of the wedge artifact is developed. In addition, the effects of the measuring condition and the setting error of the wedge artifact on the measurement result are investigated. The uncertainty for the evaluation method using a wedge artifact is assessed by a measurement experiment and simulation.

A Hard C-Means Clustering Algorithm Incorporating Membership KL Divergence and Local Data Information for Noisy Image Segmentation

2017 ◽  
Vol 32 (04) ◽  
pp. 1850012 ◽  
Author(s):  
R. R. Gharieb ◽  
G. Gendy ◽  
H. Selim
Keyword(s):  
Image Segmentation ◽  
Membership Function ◽  
Clustering Algorithm ◽  
Clustering Algorithms ◽  
Cluster Center ◽  
Local Data ◽  
Cluster Membership ◽  
Kl Divergence ◽  
Clustering Approach ◽  
Center Distance

In this paper, the standard hard C-means (HCM) clustering approach to image segmentation is modified by incorporating weighted membership Kullback–Leibler (KL) divergence and local data information into the HCM objective function. The membership KL divergence, used for fuzzification, measures the proximity between each cluster membership function of a pixel and the locally-smoothed value of the membership in the pixel vicinity. The fuzzification weight is a function of the pixel to cluster-centers distances. The used pixel to a cluster-center distance is composed of the original pixel data distance plus a fraction of the distance generated from the locally-smoothed pixel data. It is shown that the obtained membership function of a pixel is proportional to the locally-smoothed membership function of this pixel multiplied by an exponentially distributed function of the minus pixel distance relative to the minimum distance provided by the nearest cluster-center to the pixel. Therefore, since incorporating the locally-smoothed membership and data information in addition to the relative distance, which is more tolerant to additive noise than the absolute distance, the proposed algorithm has a threefold noise-handling process. The presented algorithm, named local data and membership KL divergence based fuzzy C-means (LDMKLFCM), is tested by synthetic and real-world noisy images and its results are compared with those of several FCM-based clustering algorithms.

Research on the Friction Performance of Bionic Surface Based on the Clamber Animal Foot Pad

2013 ◽  
Vol 427-429 ◽  
pp. 298-301
Author(s):  
Chun Jian Su ◽  
Zhou Yu Fu ◽  
Hui Sun ◽  
Xiao Shen
Keyword(s):  
Sliding Friction ◽  
External Surface ◽  
Surface Friction ◽  
Friction Mechanism ◽  
Micro Particles ◽  
Bionic Surface ◽  
Friction Performance ◽  
Foot Pad ◽  
The Mathematical Model ◽  
Center Distance

The clamber animal foot pads were researched by the Super Depth of Field3D Microscopic System marked VHX-600 and the flexible non-smooth surface friction mechanism of clamber animal foot pad was analysed through bionic tribology. The total friction includes two aspects: a) The sliding friction caused by the adsorbability between clamber animal foot pad and external surface. b) The embedding resistance caused by the external surface micro particles embedded into clamber animal foot pad. The mathematical model of single convex hull was built and the different center distance bionic surfaces were designed, the friction contact simulation of bionic surface was done by ANSYS and the friction performance of bionic surface was verified through the plane friction testbed.

The Detection Method of Lane Line Based on the Improved Otsu Threshold Segmentation

2015 ◽  
Vol 741 ◽  
pp. 354-358 ◽  
Author(s):  
Yang Shan Tang ◽  
Dao Hua Xia ◽  
Gui Yang Zhang ◽  
Li Na Ge ◽  
Xin Yang Yan
Keyword(s):  
Image Segmentation ◽  
Processing Time ◽  
Detection Method ◽  
Segmentation Algorithm ◽  
Test Results ◽  
Threshold Segmentation ◽  
Otsu Method ◽  
Time Requirements ◽  
Lane Line ◽  
Center Distance

For overcoming the shortage of Otsu method, proposed an improved Otsu threshold segmentation algorithm. On the basis of Otsu threshold segmentation algorithm, the gray level was divided into two classes according to the image segmentation, to determine the best threshold by comparing their center distance, so as to achieve peak line recognition under the condition of multiple gray levels. Then did experiments on image segmentation of the lane line with MATLAB by traditional Otsu threshold segmentation algorithm and the improved algorithm, the threshold of traditional Otsu threshold segmentation algorithm is 144 and the threshold of the improved Otsu threshold segmentation algorithm is 131, the processing time is within 0.453 s. Test results show that the white part markings appear more, the intersection place of white lines and the background is more clear, so this method can identify lane markings well and meet the real-time requirements.

Experimental Study on Flexible Bare Pipe Arrays Undergoing Vortex-Induced Vibrations

2018 ◽  
Author(s):  
Y. Liu ◽  
C. Shi ◽  
Z. Liu ◽  
J. Wang ◽  
X. Bao
Keyword(s):  
Fatigue Damage ◽  
Dynamic Responses ◽  
Array Configuration ◽  
Damage Rate ◽  
Flexible Pipes ◽  
Vortex Induced Vibrations ◽  
Helical Strakes ◽  
Preliminary Study ◽  
Single Pipe ◽  
Center Distance

Vortex-induced vibration (VIV) excited by current is a major contributor to the fatigue accumulation of marine risers. For deepwater operations, several risers are often arranged together in an array configuration. In this study, a set of four identical flexible pipes of a rectangular arrangement were tested in a water tunnel. By comparing the dynamic responses of a pipe in an array with that of a single isolated pipe, the effects of the current speed and the center-to-center distance between the up-stream and downstream pipes on their dynamic responses were investigated. Fatigue damages accumulated on each pipe in an array was calculated and a factor, termed “fatigue damage amplification factor”, was defined as a ratio between the fatigue damage rate of pipe in an array and the fatigue damage rate of a single pipe at a same current condition. The results showed that for bare pipes (i.e., without helical strakes), the downstream pipes in an array configuration may have larger dynamic responses and fatigue damage rates than those of a single pipe; and, it is not always conservative to assume that the fatigue damage rate estimated for a single pipe can be used to represent the fatigue damage rates of pipes in an array. This preliminary study provided some meaningful results for the design, analysis and operation of marine riser arrays.

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