Search
Author
- Amir, Ebrahimi (2)
- Aydin, Azizi (2)
- George, Haller (2)
- James, M. Fiore (2)
- next >
Subject
- robotics (9)
- Engineering (8)
- engineering (8)
- công nghệ (3)
- next >
Date issued
- 2020 - 2023 (215)
- 2010 - 2019 (28)
- 2001 - 2009 (6)
Has File(s)
- true (249)
Search Results
In order to improve the starved lubrication condition of rolling bearings, three kinds of textures, namely dimple, groove texture, and gradient groove texture, were developed on the guiding surface of thrust ball bearings in this study. The results show that gradient groove texture has the one-way self-driving function of liquid droplets. The root mean square (RMS) value of vibration acceleration of gradient groove textured bearing (GGB) decreased by 49.1% and the kurtosis decreased by 24.6% compared with non-textured bearing (NB) due to the directional spreading effect of gradient groove textures on oil. |
This book is meant to be a second course in fluid mechanics that stresses applications dealing with external potential flows and intermediate viscous flows. Students are expected to have some background in some of the fundamental concepts of the definition of a fluid, hydrostatics, use of control volume conservation principles, initial exposure to the Navier-Stokes equations, and some elements of flow kinematics, such as streamlines and vorticity. It is not meant to be an in-depth study of potential flow or viscous flow, but is meant to expose students to additional analysis techniques for both of these categories of flows. We will see applications to aerodynamics, with analysis methods able to determine forces on arbitrary bodies. We will also examine some of the exact solutions of... |
The overarching aim of this open access book is to present self-contained theory and algorithms for investigation and prediction of electric demand peaks. A cross-section of popular demand forecasting algorithms from statistics, machine learning and mathematics is presented, followed by extreme value theory techniques with examples. In order to achieve carbon targets, good forecasts of peaks are essential. For instance, shifting demand or charging battery depends on correct demand predictions in time. Majority of forecasting algorithms historically were focused on average load prediction. In order to model the peaks, methods from extreme value theory are applied. This allows us to study extremes without making any assumption on the central parts of demand distribution and to predict... |
The issues regarding energy dissipation and component damage caused by the interface friction between a friction pair attract enormous attention to friction reduction. The key-enabling technique to realize friction reduction is the use of lubricants. The lubricants smooth the contact interfaces, achieving an ultralow friction contact, which is called superslippery or superlubricity. At present, superslippery and superlubricity are two isolated research topics. There is a lack of unified definition on superslippery and superlubricity from the viewpoint of tribology. Herein, this review aims at exploring the differences and relations between superslippery and superlubricity from their origin and application scenarios. Meanwhile, the challenges for developing superslippery surface and ... |
Today, switched reluctance machines (SRMs) play an increasingly important role in various sectors due to advantages such as robustness, simplicity of construction, low cost, insensitivity to high temperatures, and high fault tolerance. They are frequently used in fields such as aeronautics, electric and hybrid vehicles, and wind power generation. This book is a comprehensive resource on the design, modeling, and control of SRMs with methods that demonstrate their good performance as motors and generators. |
In many applications, free surface flow through rigid porous media has to be modeled. Examples refer to coastal engineering applications as well as geotechnical or biomedical applications. Albeit the frequent applications, slight inconsistencies in the formulation of the governing equations can be found in the literature. The main goal of this paper is to identify these differences and provide a quantitative assessment of different approaches. Following a review of the different formulations, simulation results obtained from three alternative formulations are compared with experimental and numerical data. Results obtained by 2D and 3D test cases indicate that the predictive differences returned by the different formulations remain small for most applications, in particular for small... |
Abrasive wear mechanisms—including two-body and three-body abrasion—dominate the performance and lifespan of tribological systems in many engineering fields, even of those operating in lubricated conditions. Bearing steel (100Cr6) pins and discs in a flat-on-flat contact were utilized in experiments together with 5 and 13 µm Al2O3-based slurries as interfacial media to shed light on the acting mechanisms. The results indicate that a speed-induced hydrodynamic effect occurred and significantly altered the systems’ frictional behavior in tests that were performed using the 5 µm slurry. Further experiments revealed that a speed-dependent hydrodynamic effect can lead to a 14% increase in film thickness and a decrease in friction of around 2/3, accompanied by a transition from two-body a... |
Overview: This textbook emphasizes connections between theory and application, making physics concepts interesting and accessible to students while maintaining the mathematical rigour inherent in the subject. Frequent, strong examples focus on how to approach a problem, how to work with the equations, and how to check and generalize the result. |
Shallow Hilbert curve patterns with easily programmable texture density were selected for laser texturing of stainless steel substrates. Two different texture path segment lengths (12 and 24 µm) and four different laser power percentages (5%, 10%, 15%, and 20%) were investigated. The textured and smooth substrates were coated with thin polydopamine/polytetrafluoroethylene (PDA/PTFE) coatings for tribological property assessment. The effects of texture density (texture area coverage) and laser power on the durability and friction of the coated surfaces were studied. |
Nine organic compounds were utilized as model lubricants to investigate the impact of functional groups on tribological performances. Nonanoic Acid with carboxyl showed the best lubrication properties, and fluid film and tribofilm were coexistent in its friction test, bringing a low friction coefficient and wear rate. In addition, the lubricant with low friction coefficient corresponded to high adsorption energy in density functional theory (DFT) calculations. And the lubricant forming adsorption film with large surface energy displayed small wear rate in friction test. |
