scholarly journals Mathematical Model for Tapping Simulation to Predict Radial Pitch Diameter Difference of threads

2021 ◽  
Author(s):  
Jie Ren ◽  
Xianguo Yan
Keyword(s):  
State Transition ◽  
Great Influence ◽  
Spindle Speed ◽  
Quality Inspection ◽  
Eigenvalues And Eigenvectors ◽  
Current Position ◽  
Damping Force ◽  
Discrete State ◽  
Main Thread

Abstract As the most important component of parts, thread has a great influence on the mechanical properties and service performance of parts. In order to ensure the quality of the thread, the thread quality inspection standard involves 11 main thread characteristics, of which the surface roughness of the thread is the most studied, and the research on Radial Pitch Diameter Difference (RPDD) is still blank. In this paper, a quasi-static model of the tapping process is developed based on the roundness error mechanism of the hole, which includes cutting force and cutting damping force. Due to the regenerative nature of cutting, the force on each cutting edge depends on both the tool’s current position and previous position. According to the eigenvalues and eigenvectors of the discrete state-transition matrix, RPDD is finally determined, and the influence of the chamfer length and the spindle speed on RPDD is simulated by this model. The results demonstrate that the chamfer length and spindle speed will affect RPDD, and the RPDD is the smallest when the chamfer length is 2 threads and the spindle speed is 1400 rev/min. The development of this model not only provides a cheap and effective method for the study of RPDD, but also lays a foundation for further experimental research.

Low-Frequency Regenerative Vibration and the Formation of Lobed Holes in Drilling

2002 ◽  
Vol 124 (2) ◽  
pp. 275-285 ◽  
Author(s):  
Philip V. Bayly ◽  
Michael T. Lamar ◽  
Sean G. Calvert
Keyword(s):  
Transition Matrix ◽  
State Transition ◽  
Low Frequency ◽  
Rotation Frequency ◽  
Static Model ◽  
Eigenvalues And Eigenvectors ◽  
Current Position ◽  
Discrete State ◽  
Large Amplitude Vibrations ◽  
Regenerative Vibration

Large-amplitude vibrations in drilling often occur at frequencies near multiples of the rotation frequency, even when these are much lower than the system’s first natural frequency. These vibrations are responsible for out-of-round, “lobed” holes. A simplified model of the mechanics of this phenomenon is presented in this paper. The model includes cutting and “rubbing” forces on the drill, but inertia and damping of the tool are neglected at low speeds. This quasi-static model remains dynamic because of the regenerative nature of cutting; the force on each cutting element depends on both the tool’s current position and its position at the time of the previous tooth passage. Characteristic solutions, including unstable retrograde “whirling” modes, are found in terms of eigenvalues and eigenvectors of a discrete state-transition matrix. These unstable modes correspond closely to behavior observed in drilling tests.

Mechanics of Regenerative Vibration in Drilling: Analytical and Experimental Study of the Formation of Lobed Holes

2001 ◽  
Author(s):  
Philip V. Bayly ◽  
Michael T. Lamar ◽  
Sean G. Calvert
Keyword(s):  
Transition Matrix ◽  
State Transition ◽  
Rotation Frequency ◽  
Static Model ◽  
Simplified Model ◽  
Eigenvalues And Eigenvectors ◽  
Current Position ◽  
Discrete State ◽  
Large Amplitude Vibrations ◽  
Regenerative Vibration

Abstract Large-amplitude vibrations in drilling often occur near multiples of the rotation frequency, even when these frequencies are much lower than the system’s first natural frequency. These vibrations are responsible for out-of-round, “lobed” holes. A simplified model of the mechanics of this phenomenon is presented in this paper. The model includes cutting and “rubbing” forces on the drill, but inertia and damping of the tool are neglected at low speeds. This quasi-static model remains dynamic because of the regenerative nature of cutting; the force on each cutting element depends on both the tool’s current position and its position at the time of the previous tooth passage. Characteristic solutions, including unstable retrograde “whirling” modes, are found in terms of eigenvalues and eigenvectors of a discrete state-transition matrix. These unstable modes correspond closely to behavior observed in drilling tests.

INFLUENCE OF BIOSTIMULANTS ON THE IMMUNE PROTECTION OF CHICKENS

2019 ◽  
Keyword(s):  
Growth And Development ◽  
Digestive System ◽  
Great Influence ◽  
Egg Laying ◽  
Growth Spurt ◽  
Immune Protection ◽  
Internal Organs ◽  
State Growth ◽  
Active Peak

Among the animals of different species chickens react in greater numbers and more noticeable to a va-riety of growth biostimulators. There are great improvements on their general state, growth spurts and development of internal organs is quicker when they are injected with small portions. Such stimulation has a great influence not only on growth and development of chickens in their first period of life but also on health and productivity later on. The most active peak of reaction is when chicken is two months old. Their internal organs, especially the digestive system, develop earlier, their genitals appear earlier and they begin egg-laying much earlier too, when chickens are being fed those biostimulants. Slaughter meat yield becomes more and quality of meat improves with the influence of stimulators. A major disease pre-vention and healing effect can be reached, since most of the biostimulants raise immune system and re-sistance of the organism. It can be the only thing to justify their usage on animals. Tests show that the most typical growth spurt of birds is from fifteen to twenty percent in normal conditions. Growth spurts are also accompanied with the rise of resistance to different infections and activation of different physio-logical processes. Growth spurts can be twice or more than written here, but those spurts are usually short-timed and often accompanied with the dysfunction of different organs

scholarly journals Face Grinding Surface Quality of High Volume Fraction SiCp/Al Composite Materials

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Xu Zhao ◽  
Yadong Gong ◽  
Guiqiang Liang ◽  
Ming Cai ◽  
Bing Han
Keyword(s):  
Friction Coefficient ◽  
Surface Morphology ◽  
Surface Quality ◽  
Volume Fraction ◽  
High Volume ◽  
Spindle Speed ◽  
High Volume Fraction ◽  
Machining Parameters ◽  
Al Composite

AbstractThe existing research on SiCp/Al composite machining mainly focuses on the machining parameters or surface morphology. However, the surface quality of SiCp/Al composites with a high volume fraction has not been extensively studied. In this study, 32 SiCp/Al specimens with a high volume fraction were prepared and their machining parameters measured. The surface quality of the specimens was then tested and the effect of the grinding parameters on the surface quality was analyzed. The grinding quality of the composite specimens was comprehensively analyzed taking the grinding force, friction coefficient, and roughness parameters as the evaluation standards. The best grinding parameters were obtained by analyzing the surface morphology. The results show that, a higher spindle speed should be chosen to obtain a better surface quality. The final surface quality is related to the friction coefficient, surface roughness, and fragmentation degree as well as the quantity and distribution of the defects. Lower feeding amount, lower grinding depth and appropriately higher spindle speed should be chosen to obtain better surface quality. Lower feeding amount, higher grinding depth and spindle speed should be chosen to balance grind efficiently and surface quality. This study proposes a systematic evaluation method, which can be used to guide the machining of SiCp/Al composites with a high volume fraction.

Analysis of Electromagnetic Inverse Model of Resistance Spot Welding

2010 ◽  
Vol 160-162 ◽  
pp. 974-979
Author(s):  
Nai Feng Fan ◽  
Zhen Luo ◽  
Yang Li ◽  
Wen Bo Xuan
Keyword(s):  
Resistance Spot Welding ◽  
Regularization Method ◽  
Spot Welding ◽  
Influence Factors ◽  
Great Influence ◽  
Welding Process ◽  
Inverse Model ◽  
Resistance Spot ◽  
Inversion Theory

Resistance spot welding (RSW) is an important welding process in modern industrial production, and the quality of welding nugget determines the strength of products to a large extent. Limited by the level of RSW quality monitor, however, RSW has rarely been applied to the fields with high welding quality requirements. Associated with the inversion theory, in this paper, an electromagnetic inverse model of RSW was established, and the analysis of influence factors, such as the layout of the probes, the discrete program and the regularization method, was implemented as well. The result shows that the layout of the probe and the regularization method has great influence on the model. When the probe is located at the y direction of x-axis or the x direction of y-axis and Conjugate Gradient method is selected, a much better outcome can be achieved.

scholarly journals A MODEL BASED ON FUZZY LINGUISTIC INFORMATION TO EVALUATE THE QUALITY OF DIGITAL LIBRARIES

2010 ◽  
Vol 09 (03) ◽  
pp. 455-472 ◽  
Author(s):  
F. J. CABRERIZO ◽  
J. LÓPEZ-GIJÓN ◽  
A. A. RUÍZ ◽  
E. HERRERA-VIEDMA
Keyword(s):  
Digital Libraries ◽  
User Satisfaction ◽  
Information Access ◽  
Great Influence ◽  
Linguistic Information ◽  
Model Based ◽  
Global Quality ◽  
Fuzzy Linguistic ◽  
The Web

The Web is changing the information access processes and it is one of the most important information media. Thus, the developments on the Web are having a great influence over the developments on others information access instruments as digital libraries. As the development of digital libraries is to satisfy user need, user satisfaction is essential for the success of a digital library. The aim of this paper is to present a model based on fuzzy linguistic information to evaluate the quality of digital libraries. The quality evaluation of digital libraries is defined using users' perceptions on the quality of digital services provided through their Websites. We assume a fuzzy linguistic modeling to represent the users' perception and apply automatic tools of fuzzy computing with words based on the LOWA and LWA operators to compute global quality evaluations of digital libraries. Additionally, we show an example of application of this model where three Spanish academic digital libraries are evaluated by fifty users.

scholarly journals Research on the Influencing Factors of "Scale Veins" of Single Point Incremental Forming Workpieces Surface

2015 ◽  
Vol 9 (1) ◽  
pp. 1025-1032
Author(s):  
Shi Pengtao ◽  
Li Yan ◽  
Yang Mingshun ◽  
Yao Zimeng
Keyword(s):  
Surface Quality ◽  
Incremental Forming ◽  
Single Point ◽  
Spindle Speed ◽  
Experimental Results ◽  
Feed Speed ◽  
Single Point Incremental Forming ◽  
Machining Parameters ◽  
The Mathematical Model

To furthermore optimize the machining parameters and improve the surface quality of the workpieces manufactured by single point incremental forming method, the formation mechanism of the sacle veins on the metal incremental froming workpieces was studied through experiment method. The influence principle of the spindle speed, the feed speed and the material of tip of tools on the length of scale veins was obtained through analyzing the experimental results and building the mathematical model among the length of scale veins were feed speed and spindle speed through measuring the roughness of surfaces and observing the appearance of the forming workpieces. The experimental results showed that, the spindle speed, the feed speed and the material of tool tips have a significant effect on the scale veins formation on the surface of forming workpieces. Therefore, an appropriate group of spindle speed and feed speed can reduce the effect of scale veins on the roughness of single point incremental forming workpieces and furthermore improve the surface quality of forming workpieces.

scholarly journals Evaluation of women’s quality of life after breast reconstruction surgery

2020 ◽  
Vol 66 (2) ◽  
Author(s):  
Marta Stanisz ◽  
Ewelina Kolak ◽  
Dorota Branecka-Woźniak ◽  
Renata Robaszkiewicz-Boukaz ◽  
Przemysław Ciepiela ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Quality Of Life ◽  
Breast Reconstruction ◽  
Great Influence ◽  
Well Being ◽  
World Health ◽  
World Health Organization Quality ◽  
Reconstruction Surgery ◽  
The Impact

Introduction: Breast cancer is the most common malignancy among women, and is usually treated surgically. Mastectomy has a great influence on the mental and physical condition of women. Breast reconstruction offers them a chance to improve their quality of life (QOL) and self-image.The main aim of the study was to gain knowledge about the impact of breast reconstruction on the QOL of women following mastectomy, and an analysis of the QOL after breast reconstruction, in the context of prosthesis effect assessment.Materials and methods: The study comprised 100 women following breast reconstructive surgery involved in 1 of the 7 “Amazon Clubs” (post-mastectomy women’s associations) in the West Pomeranian Voivodeship, northwest Poland. The study was based on the author’s questionnaire, and a shortened standardized version of the World Health Organization Quality of Life-BREF (WHOQOL-BREF) questionnaire. Statistical calculations were performed with StatSoft Statistica v10 software, adopting a significance level of p < 0.05.Results: The women who decided to have breast reconstruction surgery, noticed improved well-being (67%) and experiencedan increase in self-confidence (61%). The vast majority ofthe patients surveyed (93%) were satisfied with the effectof the prosthesis. Statistically significant differences in QOL were observed in the following spheres: rest and sleep, work capacity, negative feelings, and financial resources (p < 0.05) in relation to the evaluation of the prosthesis effect.Conclusions: 1. Breast reconstruction has a positive influence on improvements in well-being, increasing self-esteem, and the assessment of a more attractive appearance in women of all ages. 2. Breast reconstruction surgery has a positive impact on QOL and health in the physical, psychological, and environmental domains, especially in the women who are satisfied with the effects of the surgery. 3. A negative assessment of the breast reconstruction effect has an adverse influence on QOL. Identifying the factors affecting dissatisfaction with the post-operative outcome is crucial for a complete understanding of the subject, and for implementing measures aimed at improving the QOL of these women.Keywords: quality of life; mastectomy; breast cancer; breast reconstruction; breast surgery.

scholarly journals Improved Model of Scheduling Algorithm

2018 ◽  
pp. 104-106
Author(s):  
Artur Vardanyan
Keyword(s):  
High Performance ◽  
Cluster Computing ◽  
Scheduling Algorithm ◽  
Great Influence ◽  
Cluster Management ◽  
Task Scheduling Algorithm ◽  
Long Time ◽  
Improved Model ◽  
First In First Out

Cluster computing is becoming increasingly practical for high performance computing research and development. A computer cluster is a set of connected computers that work together so that, they can be viewed as a single system. Clusters offer a scalable means of linking computers together to provide an expansive environment for hosting enterprise applications. As the number of nodes in cluster configurations grows, the cluster administration becomes more challenging. We need to study the challenges of cluster management and to provide a solution. To have an effective cluster management we need to have an effective task scheduling algorithm. With the explosive growth of information, the demand on computing is sharply increasing. Due to a large number of computing tasks, the scheduling algorithm is an important part of cluster computing and has a great influence on the quality of claster service. In cluster computing, some large tasks may occupy too many resources and some small tasks may wait for a long time based on First-In-First-Out (FIFO) scheduling algorithm. This paper provides an overview of an improved scheduling algorithm that shortens the execution time of tasks and increases the resource utilization.

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