scholarly journals The Effects of Shear Stress on the Lubrication Performances of Oil Film of Large-Scale Mill Bearing

2009 ◽  
Vol 76-78 ◽  
pp. 713-718
Author(s):  
Jian Mei Wang ◽  
Qing Xue Huang ◽  
Zheng Yi Jiang ◽  
Kiet Tieu
Keyword(s):  
Shear Stress ◽  
Large Scale ◽  
Film Flow ◽  
Lubricating Oil ◽  
Oil Film ◽  
Lubrication Performance ◽  
Shear Performance ◽  
Contact Surfaces ◽  
The Relationship ◽  
Bearing System

A new coupling numerical algorithm has been developed to integrate Finite Difference Method (FDM) with Boundary Element Method (BEM) to analyze shear performance of oil film by iteratively solving a series of equations such as the film flow velocity and shear stress equations for contact bodies in bearing system. With consideration of the variations of viscosity and density with pressure and temperature, the effects of shear stress of oil film layers on lubrication performance of contact surfaces under different loadcases were discussed. Moreover, Germany-made Anton Paar MRD (Magnetic Rheologic Device) was used to determine the relationship between the viscosity and shear stress of lubricating oil. The conclusions were verified to be beneficial to the further study on lubricating performance of heavy contact components and to prolong their service lives.

Stability Influence of Different Eccentric Phases in a Rotor-Bearing System

2017 ◽  
Author(s):  
Wenchao Mo ◽  
Yinghou Jiao ◽  
Zhaobo Chen ◽  
Enjie Zhang
Keyword(s):  
Integration Method ◽  
Stable Region ◽  
The Finite Element Method ◽  
Sliding Bearings ◽  
Film Stability ◽  
Oil Film ◽  
Nonlinear Responses ◽  
Rotor Bearing ◽  
The Relationship ◽  
Bearing System

A dynamic model of a rotor–bearing system with two discs is proposed in this study. The effect of eccentric phases of two discs on the oil-film stability is investigated. Considering the gyroscopic effect, the nonlinear dynamic behavior of the rotor-bearing system with two discs is analyzed based on the Finite Element Method. Two sliding bearings are simulated by the unsteady nonlinear oil-film force based on the assumption of short bearing model. The Newmark integration method is adopted to solve the equation. The research focuses on the stable region considering the eccentric phases of two discs and nonlinear responses of the rotor–bearing system by using the Poincaré maps, bifurcation diagrams and spectrum cascades. The results indicate the influence of different eccentric phases of two discs on dynamic response. The relationship between the stable region of the rotor-bearing system and eccentric phases of two discs is obtained, which is very important for the design of the rotor-bearing system.

Research on transmission efficiency of high power hydro-viscous clutch

2019 ◽  
Vol 71 (7) ◽  
pp. 942-948
Author(s):  
Qi Sun ◽  
Fangwei Xie ◽  
Kuaidi Wan ◽  
Xinjian Guo ◽  
Jie Zhu ◽  
...  
Keyword(s):  
Rotational Speed ◽  
Power Transmission ◽  
Transmission Efficiency ◽  
Inlet Pressure ◽  
Lubricating Oil ◽  
Transmission Ratio ◽  
Content Type ◽  
Oil Film ◽  
Pressure Changes ◽  
The Relationship

Purpose The purpose of this paper is to study the influences of the oil film thickness between the friction pairs, the rotational speed of the active and passive friction disks and the inlet pressure of the lubricant on the transmission efficiency. Design/methodology/approach A mathematical model of transmission efficiency was established, and the efficiency of transmission was studied by means of numerical analysis. Findings The results demonstrate that the transmission efficiency decreases with the thickness of the oil film increases. When the thickness of oil film d = 0.1 mm, the relationship between transmission efficiency and transmission ratio is linear, that is, with the transmission ratio increases, the transmission efficiency also increases which does not change with the inlet pressure changes. However, when d = 0.1 mm, their relationship is non-linear; the efficiency increases first and then decreases as the transmission ratio increases, but decreases as the inlet pressure increases. Originality/value The authors obtained a rule is that increasing the rotational speed and reducing the inlet pressure of the lubricating oil can improve the transmission efficiency. This study can provide a theoretical basis for power transmission designing of hydro-viscous clutch.

Study on Particle Breakage and Strength Characteristic of Different Coarse-Grain Contents

2012 ◽  
Vol 246-247 ◽  
pp. 1037-1041
Author(s):  
Guang Jin Wang ◽  
Yue Tong Si ◽  
Xiang Yun Kong
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Large Scale ◽  
Particle Breakage ◽  
Coarse Grained ◽  
Stress Strain ◽  
Breakage Rate ◽  
Deep Soils ◽  
The Relationship ◽  
Coarse Grained Soil

The significant particle size grading and the particle breakage of deep soils are two major characteristics of super-high dumping-site. Based on the refitted large-scale direct shear experiments, this paper studied the particle breakage and shear strength of different coarse-grained soil. The experimental results indicates a conclusion: particle breakage index is very small when upright stress is less than 400kPa .The breakage rate increases obviously with the increase of upright stress. The particle breakage index is very little when coarse-grained contents are less than 46.0% .It increases significantly when coarse-grained contents are larger than 46.0%. Hyperbolic curves can express the relationship between particle breakage index and upright stress. The experiments studied on shear strength shows that the shear stress-strain curves are micro-softening model or micro-hardening model under low upright stress. The curves are slight-softening model at higher upright stress when the coarse-grained contents are equal to 24.0%. At coarse-grained contents equal 78.0%, the shear stress-strain curves are softening model under low upright stress. The shear strength envelope expressed nonlinear under higher upright stress.

The Research of Lubricating and Colling System of the Low-Speed and Heavy-Load Sliding Bearing

2013 ◽  
Vol 744 ◽  
pp. 95-99
Author(s):  
Pei Ming Sun ◽  
Xie Ben Wei ◽  
Shu Qin Chen
Keyword(s):  
Cooling System ◽  
Water Channel ◽  
System Structure ◽  
Lubricating Oil ◽  
Heavy Load ◽  
Monitoring Method ◽  
Sliding Bearing ◽  
Oil Film ◽  
Low Speed ◽  
Lubrication Performance

This paper analyzes the influence of lubricating oil film of the low-speed and heavy-load sliding bearing on a variety of factors. It introduces the operation of Bearing for lubricating oil film in monitoring method, common fault causes and treatment measures. Finally, the bearing cooling system structure is discussed, providing reference for practical engineering application. There are many reasons to cause the failure of the bearing lubrication such as bearing assembly defects, the error of size and cooling system problems. By detecting and contrast parameters, this study analyze the determine data and correct the fault. Through the use of reasonable structure of the oil tank and cooling water channel, we can improve the lubrication performance, and extend the bearing life. This paper analyzes the factors restricting the low speed and high load sliding bearing lubricant film, and solves the actual bearing lubrication problem.

Relationship between total plasma homocysteine and the risk of aneurysms – a meta-analysis

VASA ◽  
2020 ◽  
pp. 1-6
Author(s):  
Hanji Zhang ◽  
Dexin Yin ◽  
Yue Zhao ◽  
Yezhou Li ◽  
Dejiang Yao ◽  
...  
Keyword(s):  
Large Scale ◽  
Meta Analysis ◽  
Single Species ◽  
Total Plasma ◽  
Control Groups ◽  
Randomized Controlled ◽  
Randomized Controlled Studies ◽  
The Difference ◽  
The Relationship ◽  
Healthy Participants

Summary: Our meta-analysis focused on the relationship between homocysteine (Hcy) level and the incidence of aneurysms and looked at the relationship between smoking, hypertension and aneurysms. A systematic literature search of Pubmed, Web of Science, and Embase databases (up to March 31, 2020) resulted in the identification of 19 studies, including 2,629 aneurysm patients and 6,497 healthy participants. Combined analysis of the included studies showed that number of smoking, hypertension and hyperhomocysteinemia (HHcy) in aneurysm patients was higher than that in the control groups, and the total plasma Hcy level in aneurysm patients was also higher. These findings suggest that smoking, hypertension and HHcy may be risk factors for the development and progression of aneurysms. Although the heterogeneity of meta-analysis was significant, it was found that the heterogeneity might come from the difference between race and disease species through subgroup analysis. Large-scale randomized controlled studies of single species and single disease species are needed in the future to supplement the accuracy of the results.

New ''Cold War''

2020 ◽  
pp. 27-34
Author(s):  
Vladimir Batiuk
Keyword(s):  
Cold War ◽  
Nuclear Weapons ◽  
Armed Conflict ◽  
Large Scale ◽  
Arms Race ◽  
Ideological Struggle ◽  
Nuclear Arms Race ◽  
The Cold War ◽  
The Relationship ◽  
Nuclear Arms

In this article, the ''Cold War'' is understood as a situation where the relationship between the leading States is determined by ideological confrontation and, at the same time, the presence of nuclear weapons precludes the development of this confrontation into a large-scale armed conflict. Such a situation has developed in the years 1945–1989, during the first Cold War. We see that something similar is repeated in our time-with all the new nuances in the ideological struggle and in the nuclear arms race.

Investigating Diseases and Chemicals in COVID-19 Literature with Text Mining (Preprint)

2020 ◽  
Author(s):  
Amir Karami ◽  
Brandon Bookstaver ◽  
Melissa Nolan
Keyword(s):  
Text Mining ◽  
Literature Review ◽  
Topic Modeling ◽  
Large Scale ◽  
Clinical Manifestations ◽  
International Health ◽  
Research Papers ◽  
Strategic Plans ◽  
Funding Agencies ◽  
The Relationship

BACKGROUND The COVID-19 pandemic has impacted nearly all aspects of life and has posed significant threats to international health and the economy. Given the rapidly unfolding nature of the current pandemic, there is an urgent need to streamline literature synthesis of the growing scientific research to elucidate targeted solutions. While traditional systematic literature review studies provide valuable insights, these studies have restrictions, including analyzing a limited number of papers, having various biases, being time-consuming and labor-intensive, focusing on a few topics, incapable of trend analysis, and lack of data-driven tools. OBJECTIVE This study fills the mentioned restrictions in the literature and practice by analyzing two biomedical concepts, clinical manifestations of disease and therapeutic chemical compounds, with text mining methods in a corpus containing COVID-19 research papers and find associations between the two biomedical concepts. METHODS This research has collected papers representing COVID-19 pre-prints and peer-reviewed research published in 2020. We used frequency analysis to find highly frequent manifestations and therapeutic chemicals, representing the importance of the two biomedical concepts. This study also applied topic modeling to find the relationship between the two biomedical concepts. RESULTS We analyzed 9,298 research papers published through May 5, 2020 and found 3,645 disease-related and 2,434 chemical-related articles. The most frequent clinical manifestations of disease terminology included COVID-19, SARS, cancer, pneumonia, fever, and cough. The most frequent chemical-related terminology included Lopinavir, Ritonavir, Oxygen, Chloroquine, Remdesivir, and water. Topic modeling provided 25 categories showing relationships between our two overarching categories. These categories represent statistically significant associations between multiple aspects of each category, some connections of which were novel and not previously identified by the scientific community. CONCLUSIONS Appreciation of this context is vital due to the lack of a systematic large-scale literature review survey and the importance of fast literature review during the current COVID-19 pandemic for developing treatments. This study is beneficial to researchers for obtaining a macro-level picture of literature, to educators for knowing the scope of literature, to journals for exploring most discussed disease symptoms and pharmaceutical targets, and to policymakers and funding agencies for creating scientific strategic plans regarding COVID-19.

scholarly journals Strategic resources and smallholder performance at the bottom of the pyramid

2019 ◽  
Vol 22 (3) ◽  
pp. 365-380 ◽  
Author(s):  
Matthias Olthaar ◽  
Wilfred Dolfsma ◽  
Clemens Lutz ◽  
Florian Noseleit
Keyword(s):  
Large Scale ◽  
Business Environment ◽  
Agricultural Economics ◽  
Local Market ◽  
Bottom Of The Pyramid ◽  
Fine Grained ◽  
Strategic Resources ◽  
Relative Contribution ◽  
The Relationship ◽  
Resource Based Theory

In a competitive business environment at the Bottom of the Pyramid smallholders supplying global value chains may be thought to be at the whims of downstream large-scale players and local market forces, leaving no room for strategic entrepreneurial behavior. In such a context we test the relationship between the use of strategic resources and firm performance. We adopt the Resource Based Theory and show that seemingly homogenous smallholders deploy resources differently and, consequently, some do outperform others. We argue that the ‘resource-based theory’ results in a more fine-grained understanding of smallholder performance than approaches generally applied in agricultural economics. We develop a mixed-method approach that allows one to pinpoint relevant, industry-specific resources, and allows for empirical identification of the relative contribution of each resource to competitive advantage. The results show that proper use of quality labor, storage facilities, time of selling, and availability of animals are key capabilities.

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