scholarly journals Modeling of thermal processes in the contact zones of fuel elements

2021 ◽  
pp. 83-92
Author(s):  
Vladimir Kondratenko ◽  
Victor Kadomkin ◽  
Olga Tretiyakova
Keyword(s):  
Contact Zone ◽  
Operating Conditions ◽  
Thermal Processes ◽  
Thermal Interface ◽  
Contact Zones ◽  
Processed Material ◽  
Processing Modes ◽  
Technological Processing ◽  
Diamond Grain ◽  
Fuel Elements

In this work, using two specific examples, a general approach to the mathematical modeling of thermal processes in the contact zones of fuel elements in the development and optimization of various technological processes, systems and devices is considered. In the first example, a mathematical model of heat transfer in the contact zone (metal-hybrid thermal interface) between the heat-generating element and the heat-dissipating radiator is considered. In the second case, the thermal process in the processing of materials with a bonded diamond tool in the contact zone "diamond grain – binder – processed material" is considered and analyzed. The general approach to modeling thermal processes in the contact zones of various fuel elements makes it possible to optimize the parameters of technological processing modes and the correct operating conditions for products and systems

scholarly journals Modeling Process of Forming Flat Surface Tool for Processing Conical Parts

2020 ◽  
Vol 19 (6) ◽  
pp. 492-498
Author(s):  
A. S. Kozeruk ◽  
R. O. Dias Gonzalez ◽  
M. I. Filonova
Keyword(s):  
Contact Zone ◽  
Flat Surface ◽  
The Body ◽  
Work Piece ◽  
Second Stage ◽  
Modeling Process ◽  
Working Surface ◽  
Processed Material ◽  
Processing Modes ◽  
External Conditions

The relative actuation of the tool is considered, which makes it possible not to take into account the hard-to-determine technological coefficients depending on external conditions, as well as the physical, mechanical and technological properties of the processed material. This response is determined by the distribution of the relative sliding speeds and pressure in the contact zone of the tool and the work-piece, as well as the processing time, which are characterized by the geometric and kinematic parameters of the machine operating mechanism and processing modes. A phased simulation of the actuation process of the tool working surface is proposed: without oscillation of  the upper link and with its return-rotational  movement. According to this approach, at the first stage, the distribution of the relative sliding speeds and pressure in the contact zone of the grinding surfaces is calculated, and at the second stage, when determining the relative response at the points of the lower link (tool), the movement of these points from the areas of the contact zone with same values of the indicated quantities in the area with others is monitored. A mathematical model of the process of shaping a flat surface under conditions of free grinding of the body and counter-body is obtained, which establishes quantitative relationships between the machining modes and the shape of the treated surface and is a simulation numerical model, since it allows to obtain the distribution of relative triggering over the working surface of the tool for pre-selected time points.

scholarly journals Landscape resistance constrains hybridization across contact zones in a reproductively and morphologically polymorphic salamander

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Guillermo Velo-Antón ◽  
André Lourenço ◽  
Pedro Galán ◽  
Alfredo Nicieza ◽  
Pedro Tarroso
Keyword(s):  
Contact Zone ◽  
Environmental Heterogeneity ◽  
Evolutionary Dynamics ◽  
Morphological Differentiation ◽  
Phenotypic Traits ◽  
Hybrid Zones ◽  
Landscape Resistance ◽  
Phenotypic Differentiation ◽  
Contact Zones

AbstractExplicitly accounting for phenotypic differentiation together with environmental heterogeneity is crucial to understand the evolutionary dynamics in hybrid zones. Species showing intra-specific variation in phenotypic traits that meet across environmentally heterogeneous regions constitute excellent natural settings to study the role of phenotypic differentiation and environmental factors in shaping the spatial extent and patterns of admixture in hybrid zones. We studied three environmentally distinct contact zones where morphologically and reproductively divergent subspecies of Salamandra salamandra co-occur: the pueriparous S. s. bernardezi that is mostly parapatric to its three larviparous subspecies neighbours. We used a landscape genetics framework to: (i) characterise the spatial location and extent of each contact zone; (ii) assess patterns of introgression and hybridization between subspecies pairs; and (iii) examine the role of environmental heterogeneity in the evolutionary dynamics of hybrid zones. We found high levels of introgression between parity modes, and between distinct phenotypes, thus demonstrating the evolution to pueriparity alone or morphological differentiation do not lead to reproductive isolation between these highly divergent S. salamandra morphotypes. However, we detected substantial variation in patterns of hybridization across contact zones, being lower in the contact zone located on a topographically complex area. We highlight the importance of accounting for spatial environmental heterogeneity when studying evolutionary dynamics of hybrid zones.

ANALYSIS AND RESEARCH OF ADJUSTABILITY OF EQUIPMENT FOR INTERNAL SMALL-SIZED THREADING

2021 ◽  
Vol 2 ◽  
pp. 93-99
Author(s):  
A.O. KHARCHENKO ◽  
A.A. KHARCHENKO
Keyword(s):  
Flexible Manufacturing ◽  
Computer Aided Design ◽  
Transition Probabilities ◽  
Objective Assessment ◽  
Complete Information ◽  
Operating Conditions ◽  
Theoretical Research ◽  
Automated Production ◽  
Processing Modes ◽  
Aided Design

The article presents the results of analysis and theoretical research in the direction of improving equipment for internal threading of parts in a flexible automated production. Methods for assessing the flexibility and readjustability of equipment are considered, which can be used as the basis for the developed methodology for the synthesis of technological elements of modules in conditions of computer-aided design. It is proposed to consider the technological system of the flexible manufacturing module (FMM) of threading, as a system in which transitions from state to state occur under the action of the simplest flows with the parameters of the transition probabilities of a continuous Markov chain. The developed mathematical model, which describes the states of a FMM, taking into account the readjustment of its technological elements, makes it possible to reflect the influence on the operation of the module of the parameters of applications for the changeover of processing modes, a tool, a power threading head, basic elements of a machine tool, a device, a loading device. The structure of the model and the labeled graph of the states of the system can be improved as the number of parameters and characteristics is refined. The solution of the resulting system of equations of final probabilities using the normalization condition allows for given (or experimentally obtained) intensities of arrival and service of changeover requests for FMM of threading, to obtain the values of the probability of non-changeover operation, as well as the probabilities of finding the system in an inoperative state due to the corresponding changeovers. For complete information and an objective assessment of the preferred option for use in FMS conditions, it is also necessary to take into account the stochastic processes occurring in the system under real operating conditions.

scholarly journals Spatial and Temporal Dynamics of Contact Zones Between Chromosomal Races of House Mice, Mus musculus domesticus, on Madeira Island

Genes ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 748 ◽  
Author(s):  
Joaquim T. Tapisso ◽  
Sofia I. Gabriel ◽  
Ana Mota Cerveira ◽  
Janice Britton-Davidian ◽  
Guila Ganem ◽  
...  
Keyword(s):  
Contact Zone ◽  
Temporal Dynamics ◽  
Significant Shift ◽  
Mus Musculus Domesticus ◽  
Landscape Resistance ◽  
Sampling Area ◽  
Contact Zones ◽  
Madeira Island ◽  
The North ◽  
Chromosomal Races

Analysis of contact zones between parapatric chromosomal races can help our understanding of chromosomal divergence and its influence on the speciation process. Monitoring the position and any movement of contact zones can allow particular insights. This study investigates the present (2012–2014) and past (1998–2002) distribution of two parapatric house mouse chromosomal races—PEDC (Estreito da Calheta) and PADC (Achadas da Cruz)—on Madeira Island, aiming to identify changes in the location and width of their contact. We also extended the 1998–2002 sampling area into the range of another chromosomal race—PLDB (Lugar de Baixo). Clinal analysis indicates no major geographic alterations in the distribution and chromosomal characteristics of the PEDC and PADC races but exhibited a significant shift in position of the Rb (7.15) fusion, resulting in the narrowing of the contact zone over a 10+ year period. We discuss how this long-lasting contact zone highlights the role of landscape on mouse movements, in turn influencing the chromosomal characteristics of populations. The expansion of the sampling area revealed new chromosomal features in the north and a new contact zone in the southern range involving the PEDC and PLDB races. We discuss how different interacting mechanisms (landscape resistance, behaviour, chromosomal incompatibilities, meiotic drive) may help to explain the pattern of chromosomal variation at these contacts between chromosomal races.

Research on the CFD numerical simulation and process optimization of countercurrent–cocurrent dissolved air flotation

2019 ◽  
Vol 68 (5) ◽  
pp. 325-336
Author(s):  
Yonglei Wang ◽  
Wei Liu ◽  
Liping Tian ◽  
Ruibao Jia ◽  
Zhenqi Du ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Contact Zone ◽  
Process Optimization ◽  
Operating Conditions ◽  
Cocurrent Flow ◽  
Dissolved Gas ◽  
Dissolved Air Flotation ◽  
Simulation Results ◽  
Air Flotation ◽  
Dissolved Air

Abstract The countercurrent–cocurrent dissolved air flotation (CCDAF) process is a new type of air flotation process integrating countercurrent collision and cocurrent flow adhesion processes. The structural form of the CCDAF tank and its process parameters are the required conditions to achieve countercurrent collision and cocurrent adhesion. In this study, eight CCDAF tank process models were established with a flow rate of 0.5 m3/h. Flow field numerical simulation and process optimization of a CCDAF tank was conducted using Fluent software. The simulation results show that the optimal conditions for the CCDAF process are as follows: contact zone ascending velocity 10 mm/s, separation zone separation velocity 1.5 mm/s, dissolved gas pressure 0.45 MPa, and recirculating dissolved-gas distribution ratio R1/R2 1:1. Under these operating conditions, the flow state in the flotation tank is the most stable and the gas in the contact zone is evenly distributed. According to the simulation results, a 5 m3/h pilot plant was built. The structural dimensions were: B × L × H = 1,020 mm × 1,300 mm × 1,350 mm. The test results show that the CCDAF has a significant decontamination effect and is clearly superior to the cocurrent flow DAF process and countercurrent flow DAF process.

Modal Analysis as a Means of Researching the Vibrations in Grinding

2015 ◽  
Vol 756 ◽  
pp. 15-18
Author(s):  
Dmitrii V. Ardashev
Keyword(s):  
Close Correlation ◽  
Operating Conditions ◽  
Grinding Wheel ◽  
Sufficient Information ◽  
Main Role ◽  
Wheel Wear ◽  
Grinding Wheel Wear ◽  
Working Surface ◽  
Processed Material ◽  
General Scale

During the grinding process the main role is played by the vibrating phenomena caused by primary imbalance of a wheel, features of its structure, and also the existence of a component arising in the general scale of vibrations and caused by the change of the structure of a working surface of a grinding wheel, wear of its working abrasive grains during the process. Intensity and amount of wear of the grinding wheel depends on conditions of grinding operation – kind of grinding, processed material, etc. In turn, the existence of close correlation connection between parameters of vibrations and modes of grinding allows to assume, that vibrating processes possess sufficient information and can form the basis for an assessment and forecast the perfection factor of a grinding wheel directly in operating conditions.

scholarly journals Contact zones: Multispecies scholarship throughImperial Eyes

2019 ◽  
Vol 2 (4) ◽  
pp. 712-731 ◽  
Author(s):  
Helen F Wilson
Keyword(s):  
Discourse Analysis ◽  
Contact Zone ◽  
Human Life ◽  
Contact Zones ◽  
Colonial Histories ◽  
The Relationship ◽  
Forms Of Knowledge ◽  
Do So

The contact zone is described as the space of imperial encounter. Against a backdrop of work that has used Mary Louise Pratt's concept of the contact zone to examine culture-making, and destabilize normative understandings of division, distinction, and bordering, the paper interrogates the value of utilizing the concept in multispecies contexts. To do so, the paper considers the relationship between the contact zone and the concept of encounter, noting how they overlap and depart as approaches to questioning embodied difference, colonial histories, and immanent potential. Turning to the BBC documentary series Blue Planet II, the paper uses the concept of the contact zone and discourse analysis to examine its dominant ideas, frontiers of difference, and the means through which alternative geographies are both foreclosed and enabled. It demonstrates how the concept of the contact zone can draw attention to the ocean as the documentary's site of production, where different forms of knowledge, technology, people, elements, and non-human life grapple with each other in conditions of uneven power. In moving between narrative and oceanic contact zones, the paper raises questions about practices of knowledge-making, uneven structures of power, and decipherability, to demonstrate what can be gained from staying with the postcolonial framing of the contact zone as a critical tool of analysis in multispecies scholarship.

Transient Temperature Measurements in the Contact Zone Between Brush Seals of Kevlar and Metallic Type for Bearing Chamber Sealing Using a Pyrometric Technique

2013 ◽  
Vol 135 (8) ◽  
Author(s):  
Michael Flouros ◽  
Martin Stadlbauer ◽  
Francois Cottier ◽  
Stephan Proestler ◽  
Stefan Beichl
Keyword(s):  
Contact Zone ◽  
Operating Conditions ◽  
Temperature Measurements ◽  
Transient Temperature ◽  
Labyrinth Seals ◽  
Brush Seal ◽  
Aero Engine ◽  
Rotating Surface ◽  
Brush Seals ◽  
Engine Bearing

For the past 25 years brush seal technologies have evolved into the aero engine designs and, more generally, into the gas turbine world, not only for sealing gas areas at different pressure levels but also for sealing gas/liquid environments. This is the case in an aero engine where the bearing chambers are sealed. Aero engine bearing chambers enclose oil lubricated components such bearings and gears. In order to avoid contamination of the turbo machinery through oil loss, air blown seals are used to retain the oil into the bearing chamber. Oil loss may cause coking or ignition with the probability of an uncontained destruction of rotating parts such as disks or blades. It may also cause contamination of the air conditioning system with oil fumes thus causing health problems to the passengers and crew from such exposure. The most widely known seals for bearing chamber sealing are the labyrinth seals, however, in recent years brush seals and carbon seals have also been used. The latter are contact seals; that is, they may be installed having zero clearance to the rotating part and lift during operation when their air side is pressurized. During this survey an actual aero engine bearing chamber was modified to run with brush seals in a simulating rig. Two types of brush seals were used: (a) with bristles made of Kevlar, and (b) bristles made of a metallic material. Both types were installed with an overlap to the rotor. The targets set were twofold: (a) to measure the transient temperatures in the rotor and particularly in the contact zone between the bristles and the rotor, and (b) to measure the air leakage through the seals at different operating conditions. In order to obtain the transient temperature measurements with high fidelity, a new pyrometric technique was developed and was applied for the first time in brush seals. This technique has enabled placement of the pyrometer into the bristle's pack of the seal adjacent to the rotating surface and it could record the frictional temperature evolution in the bristles/rotor contact zone during acceleration or deceleration of the rotor. Additionally, the air consumption of the seals was measured and was compared to the air consumption through the labyrinth seals. For the metallic brush seal, up to 80% of the required sealing air can be saved, which can result, in turn, into a reduction in fuel burned by up to 1%. Furthermore, a design simplification of the bearing chamber architecture can be achieved by taking into account the reduced air flow. Even though the rotor was accelerated to high speeds up to 19,500 rpm, the produced temperature overshoots in the seal/rotor contact zone have caused no deterioration in either the materials or the oil.

scholarly journals Tracing Transit (in)Tensions Between Settler Colonized ECE Contact Zones

2019 ◽  
pp. 69-81
Author(s):  
Sherri-Lynn Yazbeck ◽  
Miriam Brown ◽  
Ildikó Danis ◽  
Narda Nelson
Keyword(s):  
British Columbia ◽  
Contact Zone ◽  
Settler Colonialism ◽  
Contact Zones ◽  
Childcare Centre ◽  
The Common

Tracing the curiosity of children, educators, and researchers at a childcare centre in Melbourne, Australia and Victoria, British Columbia, Canada, we wonder how we might connect digitally across continents while thinking with place-specific encounters and tensions. In this article we share stories and unexpected (in)tensions that arise during a FaceTiming inquiry to invite questions that unsettle sedimented notions of who and what belongs inthe colonized places in which our settler educator practices take place. Provoked by Donna Haraway’s SF string figure method and situating our work within a common worlds framework, we seek new ways of connecting and transiting between our respective contact zones. In this article, we follow and pull at unsettling threads with the giving and receiving of two puppets, Bunjil and Waa, as they travel from their home in the Australian settler contact zone to the hands of those in the Canadian settler contact zone. These practices trace how these woven threads presence transit (in)tensions continue to stretch our thinking and modes of participating in our attempts at becoming accountable within the common worlds and our stories. How might this messy work make visible our accountabilities and inheritances in places of ongoing settler colonialism?

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