scholarly journals Finite element solution of the three-dimensional system of equations of heat dynamics of friction and wear during single braking

2018 ◽  
Vol 10 (11) ◽  
pp. 168781401880864 ◽  
Author(s):  
Piotr Grzes
Keyword(s):  
Friction And Wear ◽  
Mutual Influence ◽  
Three Dimensional ◽  
Maximum Temperature ◽  
Dimensional System ◽  
System Of Equations ◽  
Sliding Velocity ◽  
Flash Temperature ◽  
Disk Brake ◽  
Discrete Contact

A three-dimensional numerical model of a disk brake to study temperature on a discrete contact of rough surfaces has been developed. It includes the system of equations formulated based on thermotribological postulates of heat dynamics of friction and wear with mutual influence of contact pressure, velocity, properties of materials, and temperature. Two approaches of calculation of the flash temperature and its influence on the maximum temperature during a single braking application were studied. Changes in the contact temperature, sliding velocity, and the thermomechanical wear during braking were shown and discussed. It was found that two of the examined variants of calculation of the flash temperature agree well for the three considered materials of the brake pads combined with the cast iron disk, at each initial sliding velocity in the range from 5 to 20 m s−1.

scholarly journals Maximum temperature of the disc during repeated braking applications

2019 ◽  
Vol 11 (3) ◽  
pp. 168781401983782 ◽  
Author(s):  
Piotr Grzes
Keyword(s):  
Friction And Wear ◽  
Element Model ◽  
Maximum Temperature ◽  
Bulk Temperature ◽  
Brake Disc ◽  
Subsequent Stage ◽  
System Of Equations ◽  
Brake Pads ◽  
Brake Application ◽  
The Mean

A computational finite element model of a brake disc for determining transient axisymmetric (two-dimensional) temperature field during repeated brake application has been proposed. The presented research is a subsequent stage of a previous study on the coupling of velocity and maximum temperature for a single braking in accordance with the system of equations of heat dynamics of friction and wear. In the analysed case, changes in the mean, flash, maximum and bulk temperature of the disc were determined and discussed. The calculations were carried out at the temperature-dependent coefficient of friction, the thermophysical properties of cast-iron disc combined with cermet brake pads and the time-varying contact pressure. The obtained results were compared with the reference values from the braking simulation at constant operating parameters and independent of temperature properties of materials. It was shown that the maximum values of the mean temperature for both cases differed slightly during the entire process. The flash temperature determined from the heat dynamics of friction and wear system of equations was the highest at the beginning and gradually decreased with the number of brake applications.

Numerical Modeling of the Thermal Performance of 3D SiP with TSV

2011 ◽  
Vol 189-193 ◽  
pp. 1610-1613
Author(s):  
Kai Lin Pan ◽  
Jing Huang ◽  
Jing Liu ◽  
Wei Tao Zhu ◽  
Guo Tao Ren
Keyword(s):  
Thermal Performance ◽  
Heat Dissipation ◽  
Three Dimensional ◽  
Electrical Performance ◽  
Maximum Temperature ◽  
Dimensional System ◽  
Continuous Increase ◽  
Key Technology ◽  
Three Dimensional System

Electronic package development is driven by the continuous increase in demands for miniaturization of products with enhanced performances. Three Dimensional System in Package (3D SiP) has become a key technology to satisfy the request. The 3D SiP with Through Silicon Via (TSV) technology is developed for chip to chip stacking in a package with superior electrical performance than conventional structures. In this study, we evaluate the thermal performance of 3D SiP with TSV technology using Finite Element Method (FEM). The evaluation topics covered impacts of various materials of mold, 3D SiP models with and without TSV, and various convention conditions. The results indicated that the role of TSVs in heat dissipation is not obvious in this study, and the maximum temperature merged in the center of the chip1 under different conditions which are considered.

scholarly journals POSSIBILITY OF FORMING A LARGE DCC IN ULTRA-RELATIVISTIC HEAVY-ION COLLISIONS

2000 ◽  
Vol 15 (15) ◽  
pp. 2269-2288
Author(s):  
SANATAN DIGAL ◽  
RAJARSHI RAY ◽  
SUPRATIM SENGUPTA ◽  
AJIT M. SRIVASTAVA
Keyword(s):  
Three Dimensional ◽  
Thermal Fluctuations ◽  
Heavy Ion ◽  
High Energy ◽  
Chiral Condensate ◽  
Relativistic Heavy Ion Collisions ◽  
Maximum Temperature ◽  
Chiral Field ◽  
Heavy Nuclei ◽  
True Vacuum

We demonstrate the possibility of forming a single, large domain of disoriented chiral condensate (DCC) in a heavy-ion collision. In our scenario, rapid initial heating of the parton system provides a driving force for the chiral field, moving it away from the true vacuum and forcing it to go to the opposite point on the vacuum manifold. This converts the entire hot region into a single DCC domain. Subsequent rolling down of the chiral field to its true vacuum will then lead to emission of a large number of (approximately) coherent pions. The requirement of suppression of thermal fluctuations to maintain the (approximate) coherence of such a large DCC domain, favors three-dimensional expansion of the plasma over the longitudinal expansion even at very early stages of evolution. This also constrains the maximum temperature of the system to lie within a window. We roughly estimate this window to be about 200–400 MeV. These results lead us to predict that extremely high energy collisions of very small nuclei (possibly hadrons) are better suited for observing signatures of a large DCC. Another possibility is to focus on peripheral collisions of heavy nuclei.

scholarly journals Topological correlators and surface defects from equivariant cohomology

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Rodolfo Panerai ◽  
Antonio Pittelli ◽  
Konstantina Polydorou
Keyword(s):  
Quantum Mechanics ◽  
Equivariant Cohomology ◽  
Surface Defects ◽  
Star Product ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Dimensional System ◽  
The Novel ◽  
One Dimensional ◽  
Dual Quantum

Abstract We find a one-dimensional protected subsector of $$ \mathcal{N} $$ N = 4 matter theories on a general class of three-dimensional manifolds. By means of equivariant localization we identify a dual quantum mechanics computing BPS correlators of the original model in three dimensions. Specifically, applying the Atiyah-Bott-Berline-Vergne formula to the original action demonstrates that this localizes on a one-dimensional action with support on the fixed-point submanifold of suitable isometries. We first show that our approach reproduces previous results obtained on S3. Then, we apply it to the novel case of S2× S1 and show that the theory localizes on two noninteracting quantum mechanics with disjoint support. We prove that the BPS operators of such models are naturally associated with a noncom- mutative star product, while their correlation functions are essentially topological. Finally, we couple the three-dimensional theory to general $$ \mathcal{N} $$ N = (2, 2) surface defects and extend the localization computation to capture the full partition function and BPS correlators of the mixed-dimensional system.

scholarly journals Effects of Natural Antioxidants on Phospholipid and Ceramide Profiles of 3D-Cultured Skin Fibroblasts Exposed to UVA or UVB Radiation

Antioxidants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 578
Author(s):  
Agnieszka Gęgotek ◽  
Wojciech Łuczaj ◽  
Elżbieta Skrzydlewska
Keyword(s):  
Ascorbic Acid ◽  
High Performance ◽  
Three Dimensional ◽  
Natural Antioxidants ◽  
Phospholipid Metabolism ◽  
Culture Conditions ◽  
Membrane Properties ◽  
Dimensional System ◽  
Uvb Radiation ◽  
Liquid Chromatograph

Ultraviolet (UV) radiation is one of the primary factors responsible for disturbances in human skin cells phospholipid metabolism. Natural compounds that are commonly used to protect skin, due to their lipophilic or hydrophilic nature, show only a narrow range of cytoprotective activity, which prompts research on their combined application. Therefore, the aim of this study was to examine the effect of ascorbic acid and rutin on the phospholipid and ceramide profiles in UV-irradiated fibroblasts cultured in a three-dimensional system that approximates the culture conditions to the dermis. An ultra-high-performance liquid chromatograph coupled with a quadrupole time-of-flight mass spectrometer was used for phospholipid and ceramide profiling. As a result of UVA and UVB cells irradiation, upregulation of phosphatidylcholines, ceramides, and downregulation of sphingomyelins were observed, while treatment with ascorbic acid and rutin of UVA/UVB-irradiated fibroblast promoted these changes to provide cells a stronger response to stress. Moreover, an upregulation of phosphatidylserines in cells exposed to UVB and treated with both antioxidants suggests the stimulation of UV-damaged cells apoptosis. Our findings provide new insight into action of rutin and ascorbic acid on regulation of phospholipid metabolism, which improves dermis fibroblast membrane properties.

scholarly journals Adjustment of an Integrated Geodetic Network Composed of GNSS Vectors and Classical Terrestrial Linear Pseudo-Observations

2021 ◽  
Vol 11 (10) ◽  
pp. 4352
Author(s):  
Tadeusz Gargula
Keyword(s):  
Three Dimensional ◽  
Geodetic Network ◽  
Global Navigation Satellite Systems ◽  
Adjustment Process ◽  
Dimensional System ◽  
Integrated Network ◽  
Satellite Systems ◽  
Linear Distance ◽  
Easy Integration ◽  
Global Navigation Satellite

The paper proposes a new method for adjusting classical terrestrial observations (total station) together with satellite (GNSS-Global Navigation Satellite Systems) vectors. All the observations are adjusted in a single common three-dimensional system of reference. The proposed method does not require the observations to be projected onto an ellipsoid or converted between reference systems. The adjustment process follows the transformation of a classical geodetic network (distances and horizontal and vertical angles) into a spatial linear (distance) network. This step facilitates easy integration with GNSS vectors when results are numerically processed. The paper offers detailed formulas for calculating pseudo-observations (spatial distances) from input terrestrial observations (horizontal and vertical angles, horizontal distances, height of instrument and height of target). The next stage was to set observation equations and transform them into a linear form (functional adjustment model of geodetic observations). A method was provided as well for determining the mean errors of the pseudo-observations, necessary to assess the accuracy of the values following the adjustment (point coordinates). The proposed algorithm was verified in practice whereby an integrated network made up of a GNSS vector network and a classical linear-angular network was adjusted.

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