scholarly journals Influence of the Lubrication Oil Temperature on the Disengaging Dynamic Characteristics of a Cu-Based Wet Multi-Disc Clutch

2021 ◽  
Vol 11 (23) ◽  
pp. 11299
Author(s):  
Liangjie Zheng ◽  
Biao Ma ◽  
Man Chen ◽  
Liang Yu ◽  
Qian Wang
Keyword(s):  
Dynamic Characteristics ◽  
Hydrodynamic Lubrication ◽  
Friction Pair ◽  
Automatic Transmission ◽  
Friction Torque ◽  
Asperity Contact ◽  
Uniformity Coefficient ◽  
Lubrication Oil ◽  
The Impact ◽  
First Time

Clutch disengaging dynamic characteristics, including the disengaging duration and the variations of friction pair gaps and friction torque, are crucial to the shifting control of an automatic transmission. In the present paper, the influence of lubrication oil (ATF) temperature on disengaging dynamic characteristics is investigated through a comprehensive numerical model for the clutch disengaging process, which considers the hydrodynamic lubrication, the asperity contact, the heat transfer, the spline resistance, and the impact between the piston and clutch hub. Moreover, the non-uniformity coefficient (NUC) is proposed to characterize the disengaging uniformity of friction pairs. As the ATF temperature increases from 60 °C to 140 °C, the clutch disengaging duration shortens remarkably (shortened by 55.1%); besides, the NUC sees a decreasing trend before a slight increase. When the ATF temperature is 80 °C, the distribution of friction pair gaps is most uniform. During the disengaging process, the increase of ATF temperature not only accelerates the change of the lubrication status between friction pairs but also contributes to the decrease of contact torque and hydrodynamic torque. This research demonstrates for the first time, evidence for clutch disengaging dynamic characteristics with the consideration of ATF temperature.

Research on the Wet Clutch Engagement Torque

2014 ◽  
Author(s):  
Yingying Zhang ◽  
Changle Xiang
Keyword(s):  
Rough Surface ◽  
Automatic Transmission ◽  
Squeeze Film ◽  
Real Contact Area ◽  
Asperity Contact ◽  
Time Flow ◽  
Clutch Engagement ◽  
Wet Clutch ◽  
Lubrication Oil ◽  
Engagement Process

The driving performance of the vehicle with automatic transmission is influenced by the performance of the wet clutch directly. But at present it is still a challenge to build a reliable predictable model for the torque of the engagement process of the wet clutch. Focusing on the wet clutch of vehicle, this paper starts from mechanism analysis, and a modified Reynolds equation with the consideration of the centrifugal force of the squeeze-film is established. In the model, we can consider the speeds of the friction and separator plates independently. At the same time, flow factors have been used to research the impacts of rough surface on the flow of the lubrication oil. In the three-dimensional solution domain, the circumferential pressure gradient of lubrication oil is considered. The model is solved with the finite volume method. The simulation of the torque of the asperity contact calculates the real contact area changed with the engagement process, and the microscopic texture direction of rough surface is considered. Subsequently, the squeeze-film flow model is combined with the asperity contact model to create an integrated clutch engagement model. Finally, the influence of applied force, viscosity of lubrication oil, friction material, the depth of grooves and the width of the grooves are investigated. Based on the comparison with the experimental data, the performance of the proposed model is found satisfactory. Because in this model more detail properties of material and geometric features of the friction plate are include, the wet clutch model developed in this research can become a baseline model for the prediction of the engagement behavior of a real wet clutch. The present model may become an efficient alternative to laboratory testing and lead to designs that can not be envisioned by other approaches.

Research on the Dynamic Characteristics of NC Boring Machine Spindle System Based on Finite Element Analysis

2013 ◽  
Vol 819 ◽  
pp. 71-75
Author(s):  
Feng Jiao ◽  
Guang Ming Sun ◽  
Jian Hui Liu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Dynamic Characteristics ◽  
Hydrodynamic Lubrication ◽  
Dynamic Stiffness ◽  
Element Analysis ◽  
Spindle System ◽  
Machine Performance ◽  
Machine Spindle ◽  
The Impact

In this paper, elastic hydrodynamic lubrication theory was introduced into bearing dynamic stiffness calculation process to take into account the impact of the oil film on the rolling stiffness. Dynamic characteristics of NC boring machine spindle system dedicated to the manufacturing of bearing retainer were studied based on finite element analysis software. The rationality of the structural design of spindle was verified in the paper. The research provided a theoretical basis for the improvement of machine performance and dynamic design of NC boring machine spindle.

scholarly journals Analysis and Experimental Validation of the Tribological and Dynamic Characteristics of Journal Bearings

2021 ◽  
Vol 313 ◽  
pp. 02001
Author(s):  
Xin Yang ◽  
Genxiang Gu ◽  
Sicong Sun ◽  
Saili Li ◽  
Jianming Zhou
Keyword(s):  
Dynamic Characteristics ◽  
Power Loss ◽  
Hydrodynamic Lubrication ◽  
Excitation Frequency ◽  
Asperity Contact ◽  
Oil Viscosity ◽  
Oil Supply ◽  
Friction Power ◽  
Bearing Clearance ◽  
Excitation Force

Sliding bearings are the main kinematic pair of a Stirling engine, and one of the main sources of friction power loss and excitation force. There is a coupling effect between the lubrication state and the excitation force. In this paper, the dynamic model of a Sapphire bearing fatigue test bed, which includes thermo-elasto-hydrodynamic (EHD) property, is established and the accuracy of the model is verified by the experimental data. Based on the model, the effects of the load, the oil supply temperature, the oil supply pressure, the bearing clearance on the tribological and dynamic characteristics are studied. With an increase in the load, the orbital path of the journal moves downward, the lubrication state changes from the full hydrodynamic lubrication to the boundary lubrication, the friction power loss increases, and the bearing excitation frequency increases. Due to the decrease of the oil viscosity, the hydraulic friction power loss decreases, but the friction power loss derived from the asperity contact increase, so does the total friction power loss. With the increase of the radial clearance, the shape of the orbital path and the minimum oil film thickness remain unchanged. The increase of the bearing clearance results in the collisions between the journal and bearing bush, thus the amplitude of the frequency multiplication component in the bearing load increases, and the asperity and the total friction power loss increase.

Static and Dynamic Characteristics of Oil Lubricated Beveled-Step Herringbone-Grooved Journal Bearings

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
M. M. Nemat-Alla ◽  
A. M. Gad ◽  
A. A. Khalil ◽  
A. M. Nasr
Keyword(s):  
Dynamic Characteristics ◽  
High Speed ◽  
Hydrodynamic Lubrication ◽  
Journal Bearings ◽  
Friction Torque ◽  
Experimental Results ◽  
Static And Dynamic Characteristics ◽  
Thrust Bearings ◽  
Rectangular Profile ◽  
The Stability

Recently, herringbone-grooved journal bearings (HGJBs) have important applications in high-speed rotating machinery. The groove action in pumping the lubricating fluid inward generates supporting stiffness and improves the stability of the bearing when operating concentrically. Several researchers have investigated the static and dynamic characteristics of HGJBs and grooved thrust bearings. Most of these investigations were theoretical and concentrated on HGJBs with rectangular-profile grooves. In the present work, the static and dynamic characteristics of the beveled-step HGJBs are experimentally investigated. The bearing attitude angle, pressure distribution, and bearing friction torque were measured on a hydrodynamic lubrication unit, and then the static and dynamic characteristics were determined. The obtained experimental results are compared to the obtained experimental results for plain journal bearing. The merits as well as the demerits of the groove profile were discussed through comparisons with plain journal bearings.

Relationship between big five personality model and abusive supervision

2019 ◽  
Vol 12 (2) ◽  
Author(s):  
Bibi Tahira ◽  
Naveed Saif ◽  
Muhammad Haroon ◽  
Sadaqat Ali
Keyword(s):  
Big Five ◽  
Abusive Supervision ◽  
State Universities ◽  
Big Five Personality ◽  
Big Five Model ◽  
The Impact ◽  
First Time ◽  
Supervisor Behavior ◽  
Moderating Role

The current study tries to understand the diverse nature of relationship between personality Big Five Model (PBFM) and student's perception of abusive supervision in higher education institutions of Khyber Pakhtoonkhwa Pakistan. Data was collected in dyads i.e. (supervisors were asked to rate their personality attributes while student were asked to rate the supervisor behavior) through adopted construct. For this purpose, data was collected from three government state universities and one Private Sector University. The focus was on MS/M.Phill and PhD student and their supervisors of the mentioned universities. After measuring normality and validity regression analysis was conducted to assess the impact of supervisor personality characteristics that leads to abusive supervision. Findings indicate interestingly that except agreeableness other four attributes of (PBFM) are play their role for abusive supervision. The results are novel in the nature as for the first time Neuroticism, openness to experience, extraversion and conscientiousness are held responsible for the abusive supervision. The study did not explore the demographic characteristics, and moderating role of organizational culture, justice and interpersonal deviances to understand the strength of relationship in more detail way. Keywords: Personality big five model, abusive supervision, HEIs

The Influence of TRIPS Compliant Patent Laws on Indian Pharmaceutical Industry

2014 ◽  
Vol 4 (1) ◽  
Author(s):  
Rupesh Rastogi ◽  
Virendra Kumar
Keyword(s):  
Pharmaceutical Industry ◽  
Patent Protection ◽  
Uruguay Round ◽  
Pharmaceutical Products ◽  
Trips Agreement ◽  
Patent Law ◽  
Patent Laws ◽  
The Impact ◽  
First Time ◽  
Indian Pharmaceutical Industry

The first legislation in India relating to patents was the Act VI of 1856. The Indian Patents and Design Act, 1911 (Act II of 1911) replaced all the previous Acts. The Act brought patent administration under the management of Controller of Patents for the first time. After Independence, it was felt that the Indian Patents & Designs Act, 1911 was not fulfilling its objective. Various comities were constituted to recommend, framing a patent law which can fulfill the requirement of Indian Industry and people. The Indian Patent Act of 1970 was enacted to achieve the above objectives. The major provisions of the act, provided for process, not the product patents in food, medicines, chemicals with a term of 14 years and 5-7 for chemicals and drugs. The Act enabled Indian citizens to access cheapest medicines in the world and paved a way for exponential growth of Indian Pharmaceutical Industry. TRIPS agreement, which is one of the important results of the Uruguay Round, mandated strong patent protection, especially for pharmaceutical products, thereby allowing the patenting of NCEs, compounds and processes. India is thereby required to meet the minimum standards under the TRIPS Agreement in relation to patents and the pharmaceutical industry. India’s patent legislation must now include provisions for availability of patents for both pharmaceutical products and processes inventions. The present paper examines the impact of change in Indian Patent law on Pharmaceutical Industry.

The impact of traditional plants and their secondary metabolites in the discovery of COVID-19 treatment

2020 ◽  
Vol 26 ◽  
Author(s):  
Shabana Bibi ◽  
Ayesha Sarfraz ◽  
Ghazala Mustafa ◽  
Zeeshan Ahmed ◽  
Muhammad Aurang Zeb ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Test System ◽  
Chemical Information ◽  
System Type ◽  
The Family ◽  
Comprehensive Search ◽  
Coronavirus Infection ◽  
The Impact ◽  
First Time ◽  
Plant Sources

Background: Coronavirus Disease-2019 belongs to the family of viruses which cause a serious pneumonia along with fever, breathing issues and infection of lungs for the first time in China and later spread worldwide. Objective: Several studies and clinical trials have been conducted to identify potential drugs and vaccines for Coronavirus Disease-2019. The present study listed natural secondary metabolites identified from plant sources with antiviral properties and could be safer and tolerable treatment for Coronavirus Disease-2019. Methods: A comprehensive search on the reported studies was conducted using different search engine such as Google scholar, SciFinder, Sciencedirect, Medline PubMed, and Scopus for the collection of research articles based on plantderived secondary metabolites, herbal extracts, and traditional medicine for coronavirus infections. Results: Status of COVID-19 worldwide and information of important molecular targets involved in COVID-19 is described and through literature search, is highlighted that numerous plant species and their extracts possess antiviral properties and studied with respect to Coronavirus treatments. Chemical information, plant source, test system type with mechanism of action for each secondary metabolite is also mentioned in this review paper. Conclusion: The present review has listed plants that have presented antiviral potential in the previous coronavirus pandemics and their secondary metabolites which could be significant for the development of novel and a safer drug which could prevent and cure coronavirus infection worldwide.

Individual and Combined Assessment of Ser680Asn FSH Receptor and FSHβ -211 G>T Gene Polymorphisms in Ovarian Response in IVF/ICSI Program

2020 ◽  
Vol 21 ◽  
Author(s):  
Elli Anagnostou ◽  
Alexia Kafkoutsou ◽  
Despina Mavrogianni ◽  
Ekaterini Domali ◽  
Evangelia Dimitroulia ◽  
...  
Keyword(s):  
Gene Polymorphism ◽  
Gene Polymorphisms ◽  
Ovarian Response ◽  
Greek Population ◽  
Control Group ◽  
Genotype Distribution ◽  
Β Subunit ◽  
Molecular Genetic Study ◽  
The Impact ◽  
First Time

Background: Molecular biology tools, such as the detection of single nucleotide polymorphisms (SNPs), have been considered to assist to the management of the ovarian stimulation protocols. Purpose: The aim of this study was to evaluate the impact of two polymorphisms, the Asn680Ser polymorphism of the FSHR gene, and the FSH β subunit (FSHβ) gene polymorphism -211 G>T, in a Greek population of women undergoing IVF/ICSI program in our center. In addition, a control group of fertile women was studied, to verify whether there are differences in the genotype distribution between fertile and infertile population for both polymorphisms, as the FSHβ gene polymorphism -211 G>T is studied for the first time in the Greek population. Results : The FSH β-211 G>T polymorphism, studied for the first time in the Greek infertile population, appears to be quite rare. When studying the two polymorphisms separately, statistically significant differences were obtained that concerned the LH levels. Discussion: According to the combination analysis of the two polymorphisms by the number of alleles, women with 2-3 polymorphic alleles needed more days of stimulation, but there were no differences in pregnancy rates. Conclusion: This molecular genetic study helps to elucidate whether the polygenic combination of the Asn680Ser and FSH β subunit -211 G>T gene polymorphisms is of additive value in the prediction of ovarian response to exogenous gonadotropins.

Reconstituting the International, 1918–1923

2017 ◽  
Author(s):  
Talbot C. Imlay
Keyword(s):  
Seismic Events ◽  
Great War ◽  
Bolshevik Revolution ◽  
Meaning And Purpose ◽  
Post War ◽  
The Impact ◽  
First Time ◽  
The Great War ◽  
Do So ◽  
Lengthy Process

This chapter examines the post-war efforts of European socialists to reconstitute the Socialist International. Initial efforts to cooperate culminated in an international socialist conference in Berne in February 1919 at which socialists from the two wartime camps met for the first time. In the end, however, it would take four years to reconstitute the International with the creation of the Labour and Socialist International (LSI) in 1923. That it took so long to do so is a testimony to the impact of the Great War and to the Bolshevik revolution. Together, these two seismic events compelled socialists to reconsider the meaning and purpose of socialism. The search for answers sparked prolonged debates between and within the major parties, profoundly reconfiguring the pre-war world of European socialism. One prominent stake in this lengthy process, moreover, was the nature of socialist internationalism—both its content and its functioning.

scholarly journals Autism Tsunami: the Impact of Rising Prevalence on the Societal Cost of Autism in the United States

2021 ◽  
Author(s):  
Mark Blaxill ◽  
Toby Rogers ◽  
Cynthia Nevison
Keyword(s):  
Forecast Model ◽  
The United States ◽  
Population Projections ◽  
Base Case ◽  
Prevention Strategies ◽  
Total Base ◽  
Cost Categories ◽  
The Cost ◽  
The Impact ◽  
First Time

AbstractThe cost of ASD in the U.S. is estimated using a forecast model that for the first time accounts for the true historical increase in ASD. Model inputs include ASD prevalence, census population projections, six cost categories, ten age brackets, inflation projections, and three future prevalence scenarios. Future ASD costs increase dramatically: total base-case costs of $223 (175–271) billion/year are estimated in 2020; $589 billion/year in 2030, $1.36 trillion/year in 2040, and $5.54 (4.29–6.78) trillion/year by 2060, with substantial potential savings through ASD prevention. Rising prevalence, the shift from child to adult-dominated costs, the transfer of costs from parents onto government, and the soaring total costs raise pressing policy questions and demand an urgent focus on prevention strategies.

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