scholarly journals Influence of Electro-Erosive Modification Modes for Worn Working Surface of Dental Cutters on Restoration of its Cutting Ability

2020 ◽  
Vol 19 (4) ◽  
pp. 288-296
Author(s):  
M. G. Kiselev ◽  
S. G. Monich ◽  
P. S. Bogdan ◽  
D. L. Korchigin ◽  
V. V. Efimenko
Keyword(s):  
Experimental Data ◽  
Electric Discharge ◽  
Storage Capacitor ◽  
Initial Contour ◽  
Basic Information ◽  
Experimental Assessment ◽  
Working Surface ◽  
Modified Surface ◽  
Worn Surface

An experimental assessment has been made of the influence of electro-erosive modification modes for worn working surface of an cutter on the restoration of its cutting ability. The paper provides basic information on dental cutters. The provisions of  the experimental  research  methodology are described, including a description  of  a  device  for  modifying the worn surface of a dental cutter and a device for determining its cutting ability. Experimental data are presented and analyzed that reflect an effect on  restoration of a cutting ability of a worn surface of a dental cutter, voltage of a storage capacitor and  number of holes applied to it during its modification. Rational modes of modifying a worn-out surface of a dental mill that provide the greatest recovery of its cutting ability have been determined in the paper. It has been shown that with increasing voltage, the energy of the electric discharge acting on the treated surface increases, which leads to the formation of a single hole of a larger size on it, including metal flows along its edge that extend beyond the initial contour of the worn cutter teeth. These metal flows on the modified surface of the cutter play the role of peculiar cutting and deforming elements. It has been revealed that in the process of modifying the worn surface of the cutter, it is necessary to ensure that there is no overlap of the holes formed on it, i.e. the distance between the centers of adjacent holes should be greater than or equal to the size of metal deposits at their edges. In this case, the metal flows retain their original shape and have the highest height at these pulse parameters, which ensures a higher cutting ability of the modified cutter surface than when the holes are overlapped.

scholarly journals INFLUENCE OF EDM WORN SURFACE OF THE WORKING PART OF STEEL BORON TOOTH TO RESTORE ITS CUTTING ABILITY

2017 ◽  
Vol 16 (3) ◽  
pp. 189-195
Author(s):  
M. G. KiselevG. ◽  
P. S. Bohdan ◽  
M. M. Kryshnev ◽  
V. P. Semenkovich
Keyword(s):  
Surface Modification ◽  
Electrical Discharge Machining ◽  
Computing Time ◽  
Experimental Studies ◽  
Storage Capacitor ◽  
Basic Information ◽  
Working Surface ◽  
Cylindrical Working ◽  
Modified Surface ◽  
Worn Surface

The article is devoted to the experimental evaluation of the efficacy of electrical discharge machining (modification) worn cylindrical working surface of the steel of boron in order to restore its cutting ability. It provides basic informationabout steel dental forests, including their structure and the main stages of production. It is noted that for such resource hog maximum computing time is about 9 minutes and then further worn drills are used and recycled. Based on an analysis of previous studies on the use of EDM surface modification of the wire, tape and disk recovery tools grounded prospect worn cutting ability of the working surface of the steel by its boron EDM with a view to its use in dental practice as well as in the production of dental products. Provides basic information about how to conduct experimental studies, including a description of the device for modifying the EDM worn working surface boron, as well as the device to determine its cutting ability on the intensity of cutting them a sample of the PCB. It was established experimentally that the resulting EDM modifying worn working surface boron therein forming wells having on the edges of the metal beading beyond the original contour of the surface, the height of which increases as the process of modifying U voltages on the storage capacitor, which leads to an increase in surface finish diameter boron. It has been shown that these spatter justified regarded as a kind of cutting elements (teeth) on the modified surface of the boron, giving it a worn surface of the cutting ability. It was established experimentally that the spark erosion boron worn surface modification can restore its cutting performance with respect to the original when U = 75 to 33.3%, and when U = 120 V - 43%, indicating a relatively high recovery efficiency of the proposed method of cutting the ability of the worn surface of steel dental burs.

РОЛЬ ФИЗИЧЕСКОЙ РАЗМИНКИ В ПОДГОТОВКЕ К ТРЕНИРОВОЧНЫМ ЗАНЯТИЯМ И СОРЕВНОВАНИЯМ ШАХМАТИСТОВ БГУ

2019 ◽  
pp. 63-65
Author(s):  
Судоргин Е.П. ◽  
Карсакова И.Н.
Keyword(s):  
Experimental Data ◽  
Sport Performance ◽  
Warm Up ◽  
Physical Exercises ◽  
Methods Of Evaluation ◽  
Mental Fitness ◽  
Physical Preparation ◽  
Tools And Methods

Аннотация: О роли разминки перед тренировкой и соревнованиями написано много научных статьей и диссертаций. Ещё больше о значимости физической подготовки спортсменов, в том числе и шахматистов. В то же время авторы считают, что вопросу физической подготовки шахматистов и в частности разминке в научной и научно-методической литературе уделяется недостаточно внимания. В своей статье авторы приводят собственные экспериментальные данные о влиянии физических упражнений (разминки) на умственную работоспособность студентов-шахматистов БГУ и как следствие на спортивные результаты команды. Ключевые слова: Шахматы, разминка, умственная работоспособность, средства и методы разминки, методы оценки результатов. Аннотация: Машыгуунун жана мелдештердин алдында даярдоонун ролу жөнүндө көптөгөн илимий макала жана диссертация жазылган. Ошондой эле илимий жана илимий-методикалык адабияттарда шахматка даярдоого көп көңүл бурулбай жатат. Макаланын авторлору шахмат ойногон студенттерге физикалык көнүгүүлөрдүн тийгизген таасири жөнүндө өздөрүнүн эксперименталдык маалыматтарын көргөзүштү. Түйүндүү сөздөр: Шахмат, акыл-дарамет, курулуштар жана ыкмалар, баа берүү жыйынтыгы боюнча кабыл алынат. Abstract: on the role of warm-up before training and competitions written many scientific articles and theses. More about the significance of the physical preparation of athletes, including players. At the same time, the authors believe that the issue of fit- ness players and in particular workout in scientific and scientific-methodical literature neglected. In his article the authors cite their own experimental data on the influence of physical exercises (warm-up) on the mental fitness of students-BSU players and as a result the sport performance team. Keywords: chess, warm-up, mental fitness, workout tools and methods, methods of evaluation results.

scholarly journals Oxidation of Terpenoids to Achieve High-Value Flavor and Fragrances—Questioning Microalgae Oxidative Capabilities in the Biotransformation of the Sesquiterpene Valencene and of Selected Natural Apocarotenoids

Chemistry ◽  
2021 ◽  
Vol 3 (3) ◽  
pp. 821-830
Author(s):  
Davide De Simeis ◽  
Stefano Serra ◽  
Alessandro Di Fonzo ◽  
Francesco Secundo
Keyword(s):  
Experimental Data ◽  
Natural Products ◽  
Aqueous Medium ◽  
Photochemical Reaction ◽  
Substrate Oxidation ◽  
Market Size ◽  
Chlorella Sp ◽  
General Opinion ◽  
Natural Way

Natural flavor and fragrance market size is expected to grow steadily due to the rising consumer demand of natural ingredients. This market request is guided by the general opinion that the production of natural compounds leads to a reduction of pollution, with inherent advantages for the environment and people’s health. The biotransformation reactions have gained high relevance in the production of natural products. In this context, few pieces of research have described the role of microalgae in the oxidation of terpenoids. In this present study, we questioned the role of microalgal based oxidation in the synthesis of high-value flavors and fragrances. This study investigated the role of three different microalgae strains, Chlorella sp. (211.8b and 211.8p) and Chlorococcum sp. (JB3), in the oxidation of different terpenoid substrates: α-ionone, β-ionone, theaspirane and valencene. Unfortunately, the experimental data showed that the microalgal strains used are not responsible for the substrate oxidation. In fact, our experiments demonstrate that the transformation of the four starting compounds is a photochemical reaction that involves the oxygen as oxidant. Even though these findings cast a shadow on the use of these microorganisms for an industrial purpose, they open a new possible strategy to easily obtain nootkatone in a natural way by just using an aqueous medium, oxygen and light.

scholarly journals Elucidating the Complex Interactions between Stress and Epileptogenic Pathways

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Aaron R. Friedman ◽  
Luisa P. Cacheaux ◽  
Sebastian Ivens ◽  
Daniela Kaufer
Keyword(s):  
Experimental Data ◽  
Blood Brain Barrier ◽  
Inflammatory Cytokine ◽  
Stress Hormones ◽  
Brain Barrier ◽  
Barrier Dysfunction ◽  
Complex Interactions ◽  
Narrow Focus ◽  
Analytical Tools

Clinical and experimental data suggest that stress contributes to the pathology of epilepsy. We review mechanisms by which stress, primarily via stress hormones, may exacerbate epilepsy, focusing on the intersection between stress-induced pathways and the progression of pathological events that occur before, during, and after the onset of epileptogenesis. In addition to this temporal nuance, we discuss other complexities in stress-epilepsy interactions, including the role of blood-brain barrier dysfunction, neuron-glia interactions, and inflammatory/cytokine pathways that may be protective or damaging depending on context. We advocate the use of global analytical tools, such as microarray, in support of a shift away from a narrow focus on seizures and towards profiling the complex, early process of epileptogenesis, in which multiple pathways may interact to dictate the ultimate onset of chronic, recurring seizures.

EFFECTS OF ASPHYXIATION OF THE FETUS AND THE NEWBORN INFANT

PEDIATRICS ◽  
1960 ◽  
Vol 26 (4) ◽  
pp. 565-569
Author(s):  
William F. Windle
Keyword(s):  
Cerebral Palsy ◽  
Mental Retardation ◽  
Newborn Infant ◽  
Clinical Evaluation ◽  
Neurological Disorders ◽  
Basic Information ◽  
Clinical Experiences ◽  
Asphyxia Neonatorum

There is pressing need of well controlled clinical evaluation of the role of adverse factors in the prenatal, natal and early postnatal periods in the etiology of neurological disorders. This is particularly true of asphyxia neonatorum. Many articles have been written on relationships between apnea, anoxia or asphyxia and manifestations of mental retardation, cerebral palsy, epilepsy and othe neurological, psychological and behavioral defects. The majority of the writers express opinions, but give no evidence that data were collected. Controls are commonly lacking. Often no attempt to measure the variables appears to have been made. A review1 of more than 500 reports, commentaries and testimonials of clinical experiences reveals deficiency in basic information of physiology of the fetus and newborn that is nothing short of appalling.

scholarly journals Permeability of Sand-Clay Mixtures

2010 ◽  
Vol 56 (4) ◽  
pp. 299-320 ◽  
Author(s):  
G. Kacprzak ◽  
C. Boutin ◽  
T. Doanh
Keyword(s):  
Experimental Data ◽  
Actual State ◽  
Load Step ◽  
Qualitative And Quantitative ◽  
Experimental Data Point ◽  
Saturated Clay ◽  
Simplifying Assumptions ◽  
Data Point ◽  
Homogenization Methods

Abstract This study deals with the behavior of composite blends constituted of rigid and impervious grains included in saturated clay paste of kaolin, considered as permeable and deformable. Permeability tests performed during standard oedometr tests (before each load step) highlight the key role of the original and actual state of the clay paste, and show the existence of a threshold of sand grain concentration above which a structuring effect influences its permeability. In the light of these experiments some usual homogenization methods (with simplifying assumptions to make the problem manageable) are considered in order to model the mixture permeability. Qualitative and quantitative comparisons with experimental data point out their respective domain of interest and limitations of such approaches

Tribological Performance of a Non Asbestos Organic Brake Pad Using Various Organic and Mineral Fibers

2012 ◽  
Vol 585 ◽  
pp. 559-563
Author(s):  
M.A. Sai Balaji ◽  
K. Kalaichelvan
Keyword(s):  
Wear Behavior ◽  
Testing Machine ◽  
Brake Disc ◽  
Brake Pads ◽  
Degradation Temperature ◽  
Industrial Standards ◽  
Worn Surface ◽  
Acrylic Fibers ◽  
Automotive Brake

Non-Asbestos organic composite friction materials are increasingly used in automotive brake disc pad applications. The present paper deals with the role of various organic fibers Kevlar, Acrylic fibers and the Rock fiber namely the Lapinus fiber on the fade and recovery behavior of friction composites. Three different friction composites were developed with same formulation varying only the percentage of Kevlar, Acrylic and lapinus fibers within the formulation. The formulations containing 13.5% of these fibers were developed as brake pads and designated as NA01, NA02 and NA03 respectively. The chemical and Mechanical properties are tested as per Indian Industrial standards.. The composites are then tested for the tribo-performance using Chase Testing Machine following SAE J661a standards. The fade µ, recovery µ and wear are significantly influenced by the amount and type of fiber combinations. Also the TGA reveals the degradation temperature of these fibers. Composite NA 03 containing Kevlar and lapinus combination is found to have good tribo performance. Worn surface analysis by SEM has proved to be useful in understanding the wear behavior of the composites.

scholarly journals What Determines the Parameters of a Propagating Streamer: A Comparison of Outputs of the Streamer Parameter Model and of Hydrodynamic Simulations

Atmosphere ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1664
Author(s):  
Nikolai G. Lehtinen ◽  
Robert Marskar
Keyword(s):  
Experimental Data ◽  
Electric Field ◽  
Electric Discharge ◽  
Propagation Velocity ◽  
The Novel ◽  
Hydrodynamic Simulation ◽  
Hydrodynamic Simulations ◽  
Important Stage ◽  
Streamer Discharges

Electric streamer discharges (streamers) in the air are a very important stage of lightning, taking place before formation of the leader discharge, and with which an electric discharge starts from conducting objects which enhance the background electric field, such as airplanes. Despite years of research, it is still not well understood what mechanism determines the values of a streamer’s parameters, such as its radius and propagation velocity. The novel Streamer Parameter Model (SPM) was made to explain this mechanism, and to provide a way to efficiently calculate streamer parameters. Previously, we demonstrated that SPM results compared well with a limited set of experimental data. In this article, we compare SPM predictions to the published hydrodynamic simulation (HDS) results.

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