scholarly journals Whiffletree based supports for self-adjustable hydrostatic bearings

2021 ◽  
Vol 13 (12) ◽  
pp. 168781402110555
Author(s):  
Vincent van Parijs ◽  
Joep Nijssen ◽  
Ron van Ostayen
Keyword(s):  
Support System ◽  
Path Following ◽  
Shear Stiffness ◽  
Static Model ◽  
Hydrostatic Bearing ◽  
Design Considerations ◽  
Hydrostatic Bearings ◽  
Load Carrying ◽  
Bearing Design

Hydrostatic bearings are superior in terms of their friction and load carrying characteristics when compared to contact based bearings, but non-usable in applications with non-constant curvature counter surfaces. A possible solution to this limitation is the introduction of deformable hydrostatic bearings components that cope with these required deformations. To reduce the required deformation of a single bearing pad, multiple pads can be connected through a so-called whiffletree support system. In this work, a symmetric whiffletree based hydrostatic bearing embodiment is introduced. A 2D quasi-static model is introduced that allows for determining the kinetostatic and path following properties of such a type of bearing. Design considerations are given regarding the joint rotational-, normal-, and shear stiffness of each individual joint, as well as basic bearing layout. The potential of a whiffletree suspended bearing is presented through the use of a case study.

Hydrostatic bearings with multiport viscous pumps

2003 ◽  
Vol 217 (4) ◽  
pp. 333-342 ◽  
Author(s):  
H. A. Arafa ◽  
T. A. Osman
Keyword(s):  
Load Carrying Capacity ◽  
Pressure Source ◽  
Hydrostatic Bearing ◽  
Supply Pressure ◽  
Hydrostatic Bearings ◽  
Load Carrying ◽  
Viscous Pump ◽  
Bearing Stiffness ◽  
Flow Pressure ◽  
Good Agreement

An analysis of multirecess hydrostatic bearings with linear flow-pressure supply characteristics is presented. These characteristics can be obtained using either a constant supply pressure source with a laminar flow restrictor before each recess, or, as suggested in this paper, a multiport viscous pump. Analysis of the viscous pump-bearing system is made for odd numbers of recesses, and it is shown that a staggered or skip-one sequence of connection of the pump ports to the bearing recesses gives the least unbalanced reaction between the pump rotor/stator. The flow-pressure characteristics of viscous pumps with peripheral shrouded Rayleigh steps in a cylindrical configuration are derived and used to design a five-port pump to match a hydrostatic bearing. An experimental pump is designed, manufactured and tested, and the results obtained at one port show good agreement with the theoretically calculated values of pressure and flow. If this port is taken as representative of a pump, which is manufactured with higher accuracy, then the principle of having an effective multiport viscous pump is hereby validated. A simple means is suggested for making the bearing stiffness and load-carrying capacity insensitive to temperature/viscosity changes.

Reflection on Learner-Led Study Abroad Events in a SAC from Three Perspectives: A Learner, an Administrative Staff Member, and an Advisor

Relay Journal ◽  
2020 ◽  
pp. 66-79
Author(s):  
Mizuki Shibata ◽  
Chihiro Hayashi ◽  
Yuri Imamura
Keyword(s):  
Study Abroad ◽  
Language Learning ◽  
Support System ◽  
Staff Member ◽  
Administrative Staff ◽  
Multiple Reflections ◽  
Learning Space ◽  
Japanese University ◽  
Staff Members

This paper reports on a case study of learner-led study-abroad events in the language learning space at a Japanese University. We present multiple reflections on the events from different perspectives: the event organizer (student), an administrative staff member, and a learning advisor working at the center. We also introduce the support system that a group of administrative staff members and learning advisors are in charge of helping learners to hold their events. Moreover, throughout our reflections, several factors that made the learner-led study-abroad events sustainable and successful are demonstrated.

Review of Research on Hydrostatic Bearings

2020 ◽  
Vol 13 ◽  
Author(s):  
Xiaodong Yu ◽  
Yu Wang ◽  
Junfeng Wang ◽  
Wenkai Zhou ◽  
Hongwei Bi ◽  
...  
Keyword(s):  
High Speed ◽  
Static Pressure ◽  
Development Trend ◽  
Cnc Machining ◽  
Pressure Effects ◽  
Cnc Machine Tools ◽  
Future Research ◽  
Theoretical Formula ◽  
Hydrostatic Bearing ◽  
Hydrostatic Bearings

Background: Hydrostatic bearings have the advantages of strong bearing capacity, good stability, small friction coefficient and long life. The performance of liquid hydrostatic bearings directly affect the accuracy and efficiency of CNC machining equipment. The performance is conducive to the development of CNC machine tools towards high speed and heavy load, so it is necessary to sort out and summarize the existing research results. Objective: This study summarizes the current development status of hydrostatic bearings and explains the development trend of hydrostatic bearings. Methods: According to the recently published journal articles and patents, the recent experimental research on hydrostatic thrust bearings is summarized. This paper summarizes many factors that affect the performance of hydrostatic bearings, and discusses the causes of various factors on hydrostatic bearings. Finally, future research on hydrostatic bearings is presented. Results: The study discusses experimental methods, simulation processes, and experimental results. Conclusion: This study can produce dynamic and static pressure effects by changing the structure of the oil cavity of the hydrostatic bearing. This effect can make up for the static pressure loss. By improving the theoretical formula and mathematical model and proposing a new simulation method, the accuracy of the hydrostatic bearing simulation is satisfied; the future development trend of the hydrostatic bearing is proposed.

Design considerations for prefabricated composite jackets for structural repair: Parametric investigation and case study

2020 ◽  
pp. 113288
Author(s):  
Ali A. Mohammed ◽  
Allan Manalo ◽  
Wahid Ferdous ◽  
Rajab Abousnina ◽  
Omar AlAjarmeh ◽  
...  
Keyword(s):  
Parametric Investigation ◽  
Structural Repair ◽  
Design Considerations

scholarly journals Impact of artificial intelligence support on accuracy and reading time in breast tomosynthesis image interpretation: a multi-reader multi-case study

2021 ◽  
Author(s):  
Suzanne L. van Winkel ◽  
Alejandro Rodríguez-Ruiz ◽  
Linda Appelman ◽  
Albert Gubern-Mérida ◽  
Nico Karssemeijer ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Artificial Intelligence ◽  
Cancer Detection ◽  
Support System ◽  
Reading Time ◽  
Digital Breast Tomosynthesis ◽  
Breast Tomosynthesis ◽  
Screening Programs ◽  
The Impact

Abstract Objectives Digital breast tomosynthesis (DBT) increases sensitivity of mammography and is increasingly implemented in breast cancer screening. However, the large volume of images increases the risk of reading errors and reading time. This study aims to investigate whether the accuracy of breast radiologists reading wide-angle DBT increases with the aid of an artificial intelligence (AI) support system. Also, the impact on reading time was assessed and the stand-alone performance of the AI system in the detection of malignancies was compared to the average radiologist. Methods A multi-reader multi-case study was performed with 240 bilateral DBT exams (71 breasts with cancer lesions, 70 breasts with benign findings, 339 normal breasts). Exams were interpreted by 18 radiologists, with and without AI support, providing cancer suspicion scores per breast. Using AI support, radiologists were shown examination-based and region-based cancer likelihood scores. Area under the receiver operating characteristic curve (AUC) and reading time per exam were compared between reading conditions using mixed-models analysis of variance. Results On average, the AUC was higher using AI support (0.863 vs 0.833; p = 0.0025). Using AI support, reading time per DBT exam was reduced (p < 0.001) from 41 (95% CI = 39–42 s) to 36 s (95% CI = 35– 37 s). The AUC of the stand-alone AI system was non-inferior to the AUC of the average radiologist (+0.007, p = 0.8115). Conclusions Radiologists improved their cancer detection and reduced reading time when evaluating DBT examinations using an AI reading support system. Key Points • Radiologists improved their cancer detection accuracy in digital breast tomosynthesis (DBT) when using an AI system for support, while simultaneously reducing reading time. • The stand-alone breast cancer detection performance of an AI system is non-inferior to the average performance of radiologists for reading digital breast tomosynthesis exams. • The use of an AI support system could make advanced and more reliable imaging techniques more accessible and could allow for more cost-effective breast screening programs with DBT.

Determination of the Discharge Coefficient of a Thin-Walled Orifice Used in Hydrostatic Bearings

2005 ◽  
Vol 127 (3) ◽  
pp. 679-684 ◽  
Author(s):  
S. Charles ◽  
O. Bonneau ◽  
J. Fre^ne
Keyword(s):  
Discharge Coefficient ◽  
Ad Hoc ◽  
Thrust Bearing ◽  
Accurate Estimation ◽  
Hydrostatic Bearing ◽  
Hydrostatic Bearings ◽  
Flow Through ◽  
Thin Walled ◽  
Experimental Bench

The characteristics of hydrostatic bearings can be influenced by the compensating device they use, for example, a thin-walled orifice (diaphragm). The flow through the orifice is given by a law where an ad hoc discharge coefficient appears, and, in order to guarantee the characteristics of the hydrostatic bearing, this coefficient must be calibrated. The aim of this work is to provide an accurate estimation of the discharge coefficient under specific conditions. Therefore an experimental bench was designed and a numerical model was carried out. The results obtained then by the experimental and theoretical approach were compared with the values given by the literature. Finally, the influence of the discharge coefficient on the behavior of a thrust bearing is examined.

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