scholarly journals Contacting Stability of Sliding Electrical Contacts

2021 ◽  
Vol 288 ◽  
pp. 01009
Author(s):  
Igor Plokhov ◽  
Igor Savraev ◽  
Alexander Ilyin ◽  
Oksana Kozyreva ◽  
Sergei Loginov
Keyword(s):  
Electrical Contacts ◽  
Sliding Contact ◽  
Experimental Stand ◽  
Mathematical Expressions ◽  
Equivalent Length ◽  
Current Transmission ◽  
Instability Factor ◽  
Load Mode ◽  
Contact Unit

It is stated that the operation of the sliding contact unit is accompanied by vibrations of the brushes that occur as a result of internal and external mechanical influences. The resulting violations of the sliding contact (SC) and the instability of contacting lead to a deterioration in the quality of current transmission, increased sparking, accelerated wear of the SC. The article is devoted to the derivation and verification of universal formulas for calculating the relative instability factor (RIF) of the SC. Derived formulas allow calculating the RIF of any SC compounds. Mathematical expressions are obtained to determine the distributions of instability in the tangential and axial directions of the transition layer of the SC. An experimental stand for studying the instability of various SC compounds at idle and in the rated load mode is described. The contacting cycle, which establishes a correspondence between the instantaneous value of the length of the measuring platform and the movement of the collector is described. Expressions for determining the equivalent length of the measuring area for different cases of placing the measuring brush relative to the zone of the main sliding contact are derived. These formulas allow us to find the RIF of various SC regions on experimental data based.

Nature’s Mathematics

2019 ◽  
pp. 17-36
Author(s):  
Thomas Owens
Keyword(s):  
Material World ◽  
Geometrical Quality ◽  
Mathematical Expressions ◽  
The World ◽  
The Mind ◽  
Theological Vision

Chapter 1 explores the geometrical quality of Wordsworth’s and Coleridge’s imaginative commitments. Focusing principally on The Pedlar, the Guide to the Lakes, and Coleridge’s Notebooks, the chapter locates the origins of Wordsworth’s and Coleridge’s geometric visions in a divinely relational language of shapes which they intuited as children to describe the world about them and which moulded their shared Pedlar consciousness in the 1790s. It proposes that Wordsworth and Coleridge sustained the mathematical expressions of the Pedlar’s ethico-theological vision in their dealings with nature and the mind, perceiving in the material world a language of geometric forms which held it together.

Profiling Rotors for Limaçon-to-Limaçon Compression-Expansion Machines

2005 ◽  
Vol 128 (4) ◽  
pp. 787-793 ◽  
Author(s):  
Ibrahim A. Sultan
Keyword(s):  
Nonlinear Equations ◽  
Volumetric Efficiency ◽  
Radial Clearance ◽  
A Value ◽  
First Case ◽  
Rotor Profile ◽  
Mathematical Expressions ◽  
Second Mode ◽  
Extreme Care

Limaçon-to-limaçon compression-expansion machines have housings and rotors whose profiles are manufactured of limaçon curves. For these machines to perform satisfactorily, extreme care should be given to the geometric particulars of their rotor profile. The main characteristics that govern the quality of the rotor profile are the volumetric efficiency and the prevention of interference. In this work, the interference problem is handled from two different mathematical standpoints: the slope of tangents to both the rotor and housing curves at the apices; and the value of the minimum radial clearance that separates the two limaçon curves. In the first case, mathematical expressions, relating the radii of the limaçon base circles is presented to ensure that interference would not take place during normal operations of the limaçon-to-limaçon machine. The second mode of analysis produces a set of nonlinear equations that can be solved to obtain a value of the radial clearance. This value has to be machined off the rotor profile to prevent interference. A numerical example is given at the end of the paper to prove the validity of the models proposed and graphs are produced to support the claims presented.

scholarly journals Using Genetic Programming with Prior Formula Knowledge to Solve Symbolic Regression Problem

2016 ◽  
Vol 2016 ◽  
pp. 1-17 ◽  
Author(s):  
Qiang Lu ◽  
Jun Ren ◽  
Zhiguang Wang
Keyword(s):  
Experimental Data ◽  
Evolutionary Algorithms ◽  
Genetic Programming ◽  
Search Space ◽  
Research Field ◽  
Benchmark Problems ◽  
Regression Problem ◽  
Mathematical Expressions ◽  
The Right

A researcher can infer mathematical expressions of functions quickly by using his professional knowledge (called Prior Knowledge). But the results he finds may be biased and restricted to his research field due to limitation of his knowledge. In contrast, Genetic Programming method can discover fitted mathematical expressions from the huge search space through running evolutionary algorithms. And its results can be generalized to accommodate different fields of knowledge. However, sinceGPhas to search a huge space, its speed of finding the results is rather slow. Therefore, in this paper, a framework of connection between Prior Formula Knowledge andGP(PFK-GP) is proposed to reduce the space ofGPsearching. The PFK is built based on the Deep Belief Network (DBN) which can identify candidate formulas that are consistent with the features of experimental data. By using these candidate formulas as the seed of a randomly generated population,PFK-GPfinds the right formulas quickly by exploring the search space of data features. We have comparedPFK-GPwith ParetoGPon regression of eight benchmark problems. The experimental results confirm that thePFK-GPcan reduce the search space and obtain the significant improvement in the quality of SR.

scholarly journals EXPERIMENTAL INVESTIGATIONS OF EFFECT OF LC-CIRCUITS ON SPARKING AND THERMAL STATE OF SLIDING ELECTRIC CONTACT UNIT

2017 ◽  
Vol 3 ◽  
pp. 150
Author(s):  
Oksana Kozyreva ◽  
Igor Plokhov ◽  
Nikita Kotkov ◽  
Igor Savraev ◽  
Alexander Ilyin
Keyword(s):  
Service Life ◽  
Thermal State ◽  
Sliding Contact ◽  
Practical Significance ◽  
Experimental Investigations ◽  
Thermal Processes ◽  
Physical Processes ◽  
Sliding Electric Contact ◽  
Contact Unit ◽  
The Impact

Such processes in electric machines having sliding contacts as sparking and overheating can be the reason of the deep electroerosive wear. Searching effective ways to reduce sparking has an obvious practical significance since it extends the service life of the sliding contact in particular and service life of the electro-mechanic units in whole. This article contains information about physical processes in the electrical sliding contact. The method of spark suppression related to LC filters introduced to the electromagnetic brush circuits is considered, the device for spark reducing is suggested. The calculations of the impact of the device for spark reducing on sparking and thermal processes in the contact pairs are described.

scholarly journals Ohmic contacts to n-type and p-type gallium antimonide whiskers

2021 ◽  
Vol 11 (1) ◽  
pp. 1-6
Author(s):  
Anatoliy Druzhynin ◽  
Keyword(s):  
Low Temperatures ◽  
Ohmic Contacts ◽  
Gallium Antimonide ◽  
Electrical Contacts ◽  
Contact Material ◽  
Pulse Shaper ◽  
Current Transmission ◽  
Flux Layer ◽  
P Type ◽  
A Current

The ohmic contacts to the n-type conductivity gallium antimonide whiskers were created due to a current pulse shaper. It was established that I–V characteristics of GaSb whiskers at low temperatures are linear, regardless of the direction of current transmission. That allows using the investigated techniques to create electrical contacts and study their electrophysical characteristics. GaSb samples with a diameter of 12 μm and 20 μm were studied at temperatures 4.2 K and 77 K. A slide table with bath and microfurnace was made for welding ohmic contacts to GaSb whiskers. Gold microwire with a diameter of 30 μm was used as a contact material. The melting was carried out under the flux layer. It was revealed that the fusion is one of the most suitable methods for creating contacts to the whiskers grown by gas transport reactions.

scholarly journals Optimization of Condition Monitoring Decision Making by the Criterion of Minimum Entropy

Entropy ◽  
2019 ◽  
Vol 21 (12) ◽  
pp. 1193
Author(s):  
Ahmed Raza ◽  
Vladimir Ulansky
Keyword(s):  
Condition Monitoring ◽  
Shannon Entropy ◽  
Preventive Maintenance ◽  
Inspection Time ◽  
Minimum Entropy ◽  
Mathematical Expressions ◽  
Scheduled Time ◽  
First Time ◽  
Deteriorating Systems

Condition-based maintenance (CBM) is a promising technique for a wide variety of deteriorating systems. Condition-based maintenance’s effectiveness largely depends on the quality of condition monitoring. The majority of CBM mathematical models consider perfect inspections, in which the system condition is assumed to be determined error-free. This article presents a mathematical model of CBM with imperfect condition monitoring conducted at discrete times. Mathematical expressions were derived for evaluating the probabilities of correct and incorrect decisions when monitoring the system condition at a scheduled time. Further, these probabilities were incorporated into the equation of the Shannon entropy. The problem of determining the optimal preventive maintenance threshold at each inspection time by the criterion of the minimum of Shannon entropy was formulated. For the first time, the article showed that Shannon’s entropy is a convex function of the preventive maintenance threshold for each moment of condition monitoring. It was also shown that the probabilities of correct and incorrect decisions depend on the time and parameters of the degradation model. Numerical calculations show that the proposed approach to determining the optimal preventive maintenance threshold can significantly reduce uncertainty when deciding on the condition of the monitoring object.

scholarly journals NUMERICAL SIMULATIONS OF STATIC STRENGTH OF NOVEL DENTAL IMPLANTS

2018 ◽  
Vol 58 (4) ◽  
pp. 259
Author(s):  
Luboš Řehounek ◽  
František Denk ◽  
Aleš Jíra
Keyword(s):  
Physical Properties ◽  
Dental Implants ◽  
Biological Tissue ◽  
Static Strength ◽  
Biomechanical Stability ◽  
Novel Variants ◽  
Mechanical And Physical Properties ◽  
Load Mode ◽  
Micromechanical Characteristics

It is important to know the mechanical and micromechanical characteristics of conventional dental implants in order to design and develop novel dental implants and surface treatments that ensure a good biomechanical stability and almost fully replace the biological tissue. A successful integration of the implant depends on its chemical, mechanical and physical properties and the quality of the bone tissue. Considering these facts, we developed two novel variants of dental implant stems with an anti-rotational geometrical solution. On these variants, we have then performed numerical analyses of static strength. Outcomes of simulations vary depending on the type of the implant and load mode.

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