The use of computational contact mechanics approaches to assess the performance of parts bearing stress concentrators

2020 ◽  
Vol 1 (103) ◽  
pp. 25-32
Author(s):  
B.A. Lyashenko ◽  
Z.A. Stotsko ◽  
O.A. Kuzin ◽  
M.O. Kuzin
Keyword(s):  
Surface Stress ◽  
Stress Concentrator ◽  
Contact Strength ◽  
Stress Concentrators ◽  
Computational Contact Mechanics ◽  
Local Properties ◽  
Non Local ◽  
Bearing Stress ◽  
The Cost ◽  
Inhomogeneous Properties

Purpose: The purpose of this work is to build new computational schemes for assessing the strength parameters of parts with inhomogeneous properties of surface layers in the presence of stress concentrators. Design/methodology/approach: Using the developed approaches of mathematical modeling and open software for calculating the structures of the FEM - FEniCS, the required thickness of the hardened zones of parts has been established, which ensures their minimum softening during operation, depending on the characteristics of the stress concentrator. Findings: It is shown that for each size of the surface stress concentrator there is a critical value of the hardening thickness, the excess of which does not affect the operational strength of the parts, but increases the cost of technological operations. Research limitations/implications: In this article proposes a method for calculating the influence of the dimensional characteristics of hardening zones on the contact strength of parts with stress concentrators under conditions of prevailing power loads. Practical implications: The results obtained in this work were used to determine the technological modes of plasma hardening, which ensure an increase in the contact strength of parts with stress concentrators, depending on their dimensional characteristics. Originality/value: Using the approaches of computational mechanics and mathematical and computer modeling, methods for controlling the contact strength of parts with inhomogeneous non-local properties in the presence of a surface stress concentrator are proposed for the first time.

Estimation of strength properties of functionally graded structures with elliptical stress concentrators

2022 ◽  
Vol 113 (1) ◽  
pp. 35-41
Author(s):  
Z.A. Stotsko ◽  
O.A. Kuzin ◽  
M.O. Kuzin ◽  
V.А. Mechnik
Keyword(s):  
Stress Concentrator ◽  
Computer Modelling ◽  
Orientation Angle ◽  
Strength Properties ◽  
Functionally Graded ◽  
Rolling Stock ◽  
Contact Strength ◽  
Stress Concentrators ◽  
The Impact ◽  
Graded Structures

Purpose: The purpose of this paper is to elaborate new calculation schemes for evaluating the strength parameters of railway rolling stock parts with non-local properties of surface layers in the presence of elliptical stress concentrators. Design/methodology/approach: Using the proposed approaches of developed mathematical modelling and open software for calculating FEniCS, it were established the most dangerous angles of stress concentrator orientation and the required thickness of the hardened zones of parts, which ensures their minimum softening during operation. Findings: It is shown that for an elliptical stress concentrator with any orientation angle, there is a certain key size of surface hardening thickness, the exceeding the value of which does not have influence on the operational strength of the parts, but rise the price of technological operations. Research limitations/implications: In this paper proposes a method for computation the impact of the orientation of the surface elliptical stress concentrators on the contact strength of parts under conditions of dominate friction power loads. Practical implications: The obtained results were used to set the modes of plasma hardening, which increase the contact strength of railway parts with elliptical stress concentrators. Originality/value: Using the approaches of contact mechanics, mathematical and computer modelling, methods of controlling the contact strength of the parts with the surface elliptical stress concentrators were proposed for the first time.

Criticism of D.B Volkov’s Teleofunctional Solution to the Problem of Mental Causation

2020 ◽  
Vol 63 (1) ◽  
pp. 116-135
Author(s):  
Anton V. Kuznetsov
Keyword(s):  
Free Will ◽  
Mental Causation ◽  
Physical Factors ◽  
Multiple Realizability ◽  
Causal Relevance ◽  
Relational Properties ◽  
Local Properties ◽  
Non Local ◽  
Mental Properties ◽  
First Editions

The articles examines the teleofunctional solution to the problem of mental causation, presented by Dmitry Volkov in his recently published book Free Will. An Illusion or an Opportunity. D.B. Volkov proposes solutions to three big metaphysical problems – mental causation, personal identity, and free will. Solving the first problem, Volkov creatively combines the advantages of Dennett’s teleofunctional model and Vasilyev’s local interactionism. Volkov’s teleofunctional model of mental causation seeks to prove the causal relevance of mental properties as non-local higher order properties. In my view, its substantiation is based on three points: (a) critics of the exclusion problem and Kim’s model of mental causation, (b) “Library of first editions” argument, (c) reduction of the causal trajectories argument (CTA 1) by Vasilyev to the counterpart argument (CTA 2) by Volkov. Each of these points faces objections. Kim’s criticism is based on an implicit confusion of two types of reduction – reduction from supervenience and from multiple realizability. The latter type does not threaten Kim’s ideas, but Volkov uses this very type in his criticism. The “Library of first editions” argument does not achieve its goal due to compositional features and because non-local relational properties are a type of external properties that cannot be causally relevant. The reduction of CTA 1 to CTA 2 is unsuccessful since, in the case of this reduction, important features of CTA 1 are lost – these are local mental properties, due to which the influence of non-local physical factors occurs. My main objection is that the concept of causally relevant non-local properties is incompatible with the very concept of cause. The set of causally relevant properties of cause can only be local.

scholarly journals Beyond the lognormal approximation: a general simulation scheme

2020 ◽  
Vol 498 (2) ◽  
pp. 2663-2675
Author(s):  
Federico Tosone ◽  
Mark C Neyrinck ◽  
Benjamin R Granett ◽  
Luigi Guzzo ◽  
Nicola Vittorio
Keyword(s):  
Correlation Function ◽  
Random Fields ◽  
Three Dimensional ◽  
Analytical Techniques ◽  
Proof Of Concept ◽  
Matter Distribution ◽  
Modest Improvement ◽  
Local Properties ◽  
Non Local ◽  
Simulation Scheme

ABSTRACT We present a public code to generate random fields with an arbitrary probability distribution function (PDF) and an arbitrary correlation function. The algorithm is cosmology independent and applicable to any stationary stochastic process over a three-dimensional grid. We implement it in the case of the matter density field, showing its benefits over the lognormal approximation, which is often used in cosmology for the generation of mock catalogues. We find that the covariance of the power spectrum from the new fast realizations is more accurate than that from a lognormal model. As a proof of concept, we also apply the new simulation scheme to the divergence of the Lagrangian displacement field. We find that information from the correlation function and the PDF of the displacement–divergence provides modest improvement over other standard analytical techniques to describe the particle field in the simulation. This suggests that further progress in this direction should come from multiscale or non-local properties of the initial matter distribution.

scholarly journals Overhead for simulating a non-local channel with local channels by quasiprobability sampling

Quantum ◽  
2021 ◽  
Vol 5 ◽  
pp. 388
Author(s):  
Kosuke Mitarai ◽  
Keisuke Fujii
Keyword(s):  
Quantum Computing ◽  
Linear Combination ◽  
Upper Bound ◽  
First Generation ◽  
Quantum Devices ◽  
Non Local ◽  
The Cost ◽  
Non Locality

As the hardware technology for quantum computing advances, its possible applications are actively searched and developed. However, such applications still suffer from the noise on quantum devices, in particular when using two-qubit gates whose fidelity is relatively low. One way to overcome this difficulty is to substitute such non-local operations by local ones. Such substitution can be performed by decomposing a non-local channel into a linear combination of local channels and simulating the original channel with a quasiprobability-based method. In this work, we first define a quantity that we call channel robustness of non-locality, which quantifies the cost for the decomposition. While this quantity is challenging to calculate for a general non-local channel, we give an upper bound for a general two-qubit unitary channel by providing an explicit decomposition. The decomposition is obtained by generalizing our previous work whose application has been restricted to a certain form of two-qubit unitary. This work develops a framework for a resource reduction suitable for first-generation quantum devices.

Stress Effects on Activity of Primary Cracks Initiating at Stress Concentrator

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1567-1572
Author(s):  
Sam Hong Song ◽  
Jin Bong Kim
Keyword(s):  
Finite Element Method ◽  
Stress Intensity Factor ◽  
Stress Distribution ◽  
Stress Concentrator ◽  
Mechanical Analysis ◽  
Mean Stress ◽  
Stress Concentrators ◽  
Stress Effects ◽  
The Mean ◽  
As Stress

This study has been performed to investigate the stress distribution around defects that behave as stress concentrators and fracture mechanical analysis for cracks initiating at stress concentrators. The stress distribution was analyzed using Finite Element Method and non-dimensional stress intensity factor was determined by the mean stress method. This method could be applied to determine the activity of primary crack initiated at the stress concentrator in experiment. In addition, stress interaction effects around defects and cracks were compared.

scholarly journals ONBOARD/ON-GROUND IMAGE PROCESSING CHAIN FOR HIGH-RESOLUTION EARTH OBSERVATION SATELLITES

2021 ◽  
Vol XLIII-B3-2021 ◽  
pp. 755-762
Author(s):  
E. Cucchetti ◽  
C. Latry ◽  
G. Blanchet ◽  
J.-M. Delvit ◽  
M. Bruno
Keyword(s):  
Image Processing ◽  
High Resolution ◽  
Mean Squared Error ◽  
Low Cost ◽  
Image Size ◽  
Processing Chain ◽  
Space Agency ◽  
Non Local ◽  
Earth Observation Satellites ◽  
The Cost

Abstract. Over the last decade, the French space agency (CNES) has designed and successfully operated high-resolution satellites such as Pléiades. High-resolution satellites typically acquire panchromatic images with fine spatial resolutions and multispectral images with coarser samplings for downlink constraints. The multispectral image is reconstructed on the ground, using pan-sharpening techniques. Onboard compression and ground processing affect however the quality of the final product. In this paper, we describe our next-generation onboard/on-ground image processing chain for high-resolution satellites. This paper focuses on onboard compression, compression artefacts correction, denoising, deconvolution and pan-sharpening. In the first part, we detail our fixed-quality compression approach, which limits compression effects to a fraction of the noise, thus preserving the useful information in an image. This approach optimises the bitrate at the cost of image size, which depends on the scene complexity. This technique requires however pre- and post-processing steps. The noisy HR images obtained after decompression are suited for non-local denoising algorithms. We show in the second part of this paper that non-local denoising outperforms previous techniques by 15% in terms of root mean-squared error when tested on simulated noiseless references. Deconvolution is also detailed. In the final part of this paper, we put forward an adaptation of this chain to low-cost CMOS Bayer colour matrices. We demonstrate that the concept of our image chain remains valid, provided slight modifications (in particular dedicated transformations of the colour planes and demosaicing). A similar chain is under investigation for future missions.

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