scholarly journals Influence of Work and Tool Materials on Parameters of Electrical Discharge Machining (Edm)

1970 ◽  
Vol 3 (1) ◽  
Author(s):  
A.K.M.N. Amin A.K.M.N. Amin ◽  
A.K. Sarder
Keyword(s):  
Electrical Conductivity ◽  
Melting Point ◽  
Recast Layer ◽  
Point Of View ◽  
Machined Surface ◽  
Tool Materials ◽  
Copper Electrodes ◽  
Wear Ratio ◽  
Tool Wear Ratio ◽  
The Given

Influence of the properties of work and tool materials on material removal rate (MRR), tool wear ratio (TWR), thickness of the recast layer, surface roughness and accuracy of machining in EDM process has been investigated. Copper brass, stainless steel, mild steel and grey cast irou have been used in various combinations as work and tool materials. From the experimental results it is found that MRR slows down with machining time. Apart from that it has been found that MRR and TWR are inversely proportional to the melting points of the work and tool materials respectively. Electrical conductivity of the tool material also has appreciable influence on tool wear ratio. Wear ratio was found to be minimum in the case of the copper electrode having maximum electrical conductivity.  It has been also observed that for all combinations of work and tool materials, a recast layer is formed on the machined surface. It has been observed that the micro cavities formed in the cases of lower melting point electrode materials like copper and brass having higher electrical conductivity are comparatively smaller in size (2-3 ?m) as compared to the sizes of the micro cavities (8-20 ?m) formed in the cases of high melting pointer electrodes having also lower electrical conductivity. Consequenty the machined surface roughness produced in the latter cases is higher.  It has been also observed that the debris concentration increases due to side sparking of the electrode. The tendency of debris concentration is the maximum at the middle of the tool-job interface resulting in high bottom surface inaccuracy, specially when high melting point work materials are machined with electrodes like brass having low melting point and relatively lower electrical conductivity. From the point of view of MRR, brass electrodes have been found to be the most suitable tool, but from the point of view of machining accuracy and surface finish copper electrodes were found to yield the best result for the given set of job materials. So it was concluded that brass electrodes should be recommended for rough machining and copper electrodes for finish machining of the given work materials.

THE ISSUE OF MINORS’S GUARDIANSHIP SENTENCED TO IMPRISONMENT

2020 ◽  
pp. 33-37
Author(s):  
Ирина Викторовна Евстафьева
Keyword(s):  
Juvenile Offenders ◽  
Legal Status ◽  
Careful Consideration ◽  
Point Of View ◽  
Sufficient Detail ◽  
Domestic Legislation ◽  
The Status ◽  
Correct Understanding ◽  
The Given

В статье исследуются вопросы попечительства в отношении несовершеннолетних, отбывающих наказание в виде лишения свободы. Проблема, поднимаемая автором настоящей статьи, многогранна, касается различных аспектов отбывания наказания несовершеннолетними в воспитательных колониях и требует комплексного исследования, способного ответить на определенно значимый вопрос: является ли колония законным представителем находящихся в ней несовершеннолетних со всеми вытекающими из статуса законных представителей последствиями. При этом необходимо обращать внимание на специфику правового статуса лиц, отбывающих наказание в воспитательных колониях, которые, во-первых, являются несовершеннолетними, то есть не обладают дееспособностью в полном объеме и нуждаются в особой заботе, защите и представительстве, а во-вторых, осуждены за совершение тяжкого или особо тяжкого преступления, влекущего изоляцию от общества и определенные ограничения и лишения. Отечественное законодательство достаточно детально регламентирует особенности режима отбывания наказания в виде лишения свободы несовершеннолетними, не определяя при этом статуса воспитательных колоний, кем они являются: воспитателями, попечителями или исключительно учреждениями исполнения наказаний. Между тем правильное понимание значения и роли воспитательной колонии в жизни находящихся в ней несовершеннолетних преступников, по мнению автора, поможет избежать ряда проблем, объективно складывающихся в учреждениях подобного рода. С этой точки зрения предлагаемая тема представляет интерес не только для ученых-теоретиков, но и для практиков - сотрудников соответствующих учреждений. Особо следует подчеркнуть, что исследований по данной тематике в специальной литературе нет. Отдельные исследования, встречающиеся в современной литературе, касаются исключительно общего гражданско-правового статуса несовершеннолетних осужденных. Однако это обстоятельство может свидетельствовать только о новизне данной темы, но никак не об отсутствии самой проблемы. The article analyzes the issues of the status of educational colonies as guardians of minors serving a sentence of imprisonment. In fact, the problem raised by the author of this article is multifaceted, concerns various aspects of the serving of punishment by minors in educational colonies and requires a comprehensive study that can answer, it seems, a definitely significant question: whether the colony is the legal representative of the minors in it with all the consequences arising from the status of legal representatives in the form of duties and responsibilities. At the same time, it seems, it is necessary to pay attention to the specifics of the legal status of citizens serving sentences in educational colonies, who, firstly, are minors, i.e. do not have full legal capacity and need special care, protection and representation, and, secondly, are convicted of committing a serious or particularly serious crime, entailing isolation from society and certain restrictions and deprivation. Domestic legislation regulates in sufficient detail the peculiarities of the regime of serving sentences in the form of deprivation of liberty by minors, without determining the status of educational colonies. Who are they: educators, Trustees or only institutions of execution of punishments. Meanwhile, the correct understanding of the importance and role of the educational colony in the life of juvenile offenders in it, according to the author, will help to avoid a number of problems that objectively develop in institutions of this kind. From this point of view, the proposed topic is of interest not only for theoretical scientists, but for practitioners-employees of relevant institutions. It should be emphasized that there are no studies on this subject in the special literature. However, this circumstance can testify only about novelty of the given subject, but in any way about absence of the problem. It seems that the relevance and importance of a problem is not always measured by the number of studies devoted to it. Sometimes these its traits are manifest only under particularly careful consideration.

scholarly journals Laws of the iterated logarithm on covering graphs with groups of polynomial volume growth

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Ryuya Namba
Keyword(s):  
Random Walks ◽  
Quadratic Forms ◽  
Volume Growth ◽  
Moderate Deviation ◽  
Point Of View ◽  
Iterated Logarithm ◽  
Large Numbers ◽  
Geometric Point ◽  
Rate Functions ◽  
The Given

AbstractModerate deviation principles (MDPs) for random walks on covering graphs with groups of polynomial volume growth are discussed in a geometric point of view. They deal with any intermediate spatial scalings between those of laws of large numbers and those of central limit theorems. The corresponding rate functions are given by quadratic forms determined by the Albanese metric associated with the given random walks. We apply MDPs to establish laws of the iterated logarithm on the covering graphs by characterizing the set of all limit points of the normalized random walks.

Modelling the nano indentation behaviour of recast layer and heat affected zone on reverse micro EDMed hemispherical feature

2021 ◽  
pp. 1-15
Author(s):  
Tribeni Roy ◽  
Anuj Sharma ◽  
Prabhat Ranjan ◽  
R. Balasubramaniam
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Heat Affected Zone ◽  
Parent Material ◽  
Recast Layer ◽  
Machined Surface ◽  
Nano Indentation ◽  
Fea Simulation ◽  
Load Displacement ◽  
Good Agreement

Abstract Electrical discharge machined surfaces inherently possess recast layer on the surface with heat affected zone (HAZ) beneath it and these have a detrimental effect on the mechanical properties viz. hardness, elastic modulus, etc. It is very difficult to experimentally characterise each machined surface. Therefore, an attempt is made in this study to numerically calculate the mechanical properties of the parent material, HAZ and the recast layer on a hemispherical protruded micro feature fabricated by reverse micro EDM (RMEDM). In the 1st stage, nano indentation was performed to experimentally determine the load-displacement plots, elastic modulus and hardness of the parent material, HAZ and the recast layer. In the 2nd stage, FEA simulation was carried out to mimic the nano indentation process and determine the load-displacement plots for all the three cases viz. parent material, recast layer and HAZ. Results demonstrated that the load'displacement plots obtained from numerical model in each case was in good agreement with that of the experimental curves. Based on simulated load-displacement plots, hardness was also calculated for parent material, HAZ and the recast layer. A maximum of 11% error was observed between simulated values of hardness and experimentally determined values.

scholarly journals Development of Antibacterial and Antifungal Triazole Chromium(III) and Cobalt(II) Complexes: Synthesis and Biological Activity Evaluations

Molecules ◽  
2018 ◽  
Vol 23 (8) ◽  
pp. 2013 ◽  
Author(s):  
Ricardo Murcia ◽  
Sandra Leal ◽  
Martha Roa ◽  
Edgar Nagles ◽  
Alvaro Muñoz-Castro ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Biological Activity ◽  
Melting Point ◽  
Inhibitory Concentration ◽  
Vero Cells ◽  
Visible Spectroscopy ◽  
Antifungal Activities ◽  
Antibacterial And Antifungal Activities ◽  
Antibacterial And Antifungal ◽  
New Compounds

In this work, six complexes (2–7) of Cr(III) and Co(II) transition metals with triazole ligands were synthesized and characterized. In addition, a new ligand, 3,5-bis(1,2,4-triazol-1-ylmethyl)toluene (1), was synthesized and full characterized. The complexes were obtained as air-stable solids and characterized by melting point, electrical conductivity, thermogravimetric analysis, and Raman, infrared and ultraviolet/visible spectroscopy. The analyses and spectral data showed that complexes 3–7 had 1:1 (M:L) stoichiometries and octahedral geometries, while 2 had a 1:2 (M:L) ratio, which was supported by DFT calculations. The complexes and their respective ligands were evaluated against bacterial and fungal strains with clinical relevance. All the complexes showed higher antibacterial and antifungal activities than the free ligands. The complexes were more active against fungi than against bacteria. The activities of the chromium complexes against Candida tropicalis are of great interest, as they showed minimum inhibitory concentration 50 (MIC50) values between 7.8 and 15.6 μg mL−1. Complexes 5 and 6 showed little effect on Vero cells, indicating that they are not cytotoxic. These results can provide an important platform for the design of new compounds with antibacterial and antifungal activities.

Polarization Characteristics to Wear Ratio of Anti-Fouling Paint

2015 ◽  
Vol 1110 ◽  
pp. 179-184
Author(s):  
Kyung Man Moon ◽  
Dong Hyun Park ◽  
Yun Hae Kim ◽  
Tae Sil Baek
Keyword(s):  
Current Density ◽  
Corrosion Potential ◽  
Wear Test ◽  
Life Time ◽  
Point Of View ◽  
Limiting Current ◽  
Limiting Current Density ◽  
Wear Ratio ◽  
Polarization Characteristics ◽  
Lower Variation

Recently, anti-fouling paints which does not include the poison components such as tin (Sn) free, copper (Cu) free have been increasingly developed in order to decrease the contamination of marine environment. Moreover, the wear ratios of these anti-fouling paints are very important problem to prolong their life time in economical and environmental point of view. In this study, four types of anti-fouling paints as self-polishing type were investigated on the relationship between their polarization characteristics and wear ratios. Relationship between wear ratio and variation ratio of polarization resistance measured in corrosion potential was not well matched with each other. However, there was a good agreement between the wear ratio and variation ratio of diffusion limiting current density, for example, the higher or the lower variation ratio of diffusion limiting current density, wear ratio also increased or decreased respectively. Consequently, it is suggested that we can qualitatively expect the life time and wear degree of anti-fouling paint by only measuring the polarization characteristics before the wear test is practically performed in the field.Keywords: Anti-fouling paint, Self-polishing type, Polarization characteristics, Wear ratio, Diffusion limiting current density, Corrosion Potential

scholarly journals Obtaining hollow semi-finished products from copper alloys for electrical applications by screw rolling method

2020 ◽  
pp. 27-38 ◽  
Author(s):  
Yu. V. Gamin ◽  
B. A. Romantsev ◽  
A. N. Pashkov ◽  
P. V. Patrin ◽  
I. A. Bystrov ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Copper Alloys ◽  
Reduction Process ◽  
Point Of View ◽  
Wall Thickening ◽  
Relative Reduction ◽  
Outer Diameter ◽  
Screw Rolling ◽  
Front End ◽  
Rolling Method

The article proposes a process for obtaining semi-finished products in the form of pipes made of copper alloys for electrical applications using the screw rolling method. The paper presents the results of experimental piercing and rolling of pipe samples made of Cu–0.75Cr copper alloy billets with a diameter of 45 mm. The 43.5×10.0 mm samples obtained after piercing using a two-roll screw rolling mill had exact geometrical dimensions: outer diameter deviation at the front end was up to 1 %, at the back end – up to 2.4 %; relative variation in wall thickness at the front end was 0.3÷0.5 %, at the rear end – 0.5÷1.0 %. Then pierced pipe samples were rolled using a three-roll radial-shear rolling (RSR) mini mill with a different total degree of reduction – samples were obtained with an outer diameter of 30, 25 and 18 mm. The reduction process was analyzed from the point of view of internal hole stability and deformation. In case of 30 % relative reduction of the outer diameter, rolling without a mandrel is accompanied by wall thickening. In this case, inner diameter deviations are within acceptable limits. The experiments on obtaining samples from the Cu–0.75Cr alloy by screw piercing and reduction in the RSR mill show that this scheme can be implemented in principle in industry. At the same time it is necessary to define more exactly deformation parameters (degree of deformation, choice of reduction scheme) to obtain a quality product. Various options for heat treatment (HT) of the obtained pipe samples and the effect of the HT method on electrical conductivity and hardness are considered. Samples after piercing had a conductivity of 59.3 % IACS. The maximum electrical conductivity of 76.7 % IACS was obtained on samples after quenching from a temperature of 1020 °C and aging at 450 °C for 3 h. The results of the work show the fundamental possibility of obtaining semi-finished products from copper alloys for electrical purposes using the screw rolling method.

scholarly journals Lak proverbs with the religious code of culture

2020 ◽  
Vol 11 (4) ◽  
Author(s):  
Mariana Abakarova
Keyword(s):  
Morphological Analysis ◽  
Semantic Analysis ◽  
Native Speakers ◽  
Point Of View ◽  
The Social ◽  
Present Participle ◽  
Cultural Code ◽  
Positive Traits ◽  
The Given ◽  
Syntactical Analysis

The article analyzes Lak proverbs with the religious cultural code. The research was based on the descriptive method, syntactical analysis, morphological analysis and cognitive analysis. The proverbs collected from 3 books of Lak proverbs were analyzed from the point of view of semantics, axiological connotations, syntax and morphology. Semantic analysis revealed 6 groups of lexemes: (1) denominations of people; (2) words related to religious pillars and rituals; (3) words related to holy scriptures, religious attributes and terms; (4) words denoting death and afterlife; (5) words denoting commendable religious acts and notions; (6) words denoting sin and punishment. In the course of the axiological analysis there have been defined proverbs with positive evaluation of a person and proverbs with negative characteristics of a person. Positive traits include honesty, piety, decency, erudition and diligence, while negative ones include insulation, indecency, hypocrisy and negligence in the religious worship. Syntactical analysis of the Lak proverbs has revealed the presence of adverbs of asyndetic structure within which there have been established adversative, concessive and comparative relations, as well as of proverbs with copulative and disjunctive conjunctions. Some of the proverbs are based on the principle of alogism. Morphological analysis of the proverbs has revealed the most frequent grammatical tense, the Present Affirmative Tense, which is formed by means of adding the affix -r to the present participle. The Present Affirmative Tense in the Lak language denotes an action as an attribute of the subject which explains the fact of usage of this tense in proverbs that summarize the social experience of the native speakers. Lak proverbs with the given code have not been researched earlier that makes this study relevant.

scholarly journals Economical assessment of an investment related to the establishment of a new farrowing place and pig-rearing building

2019 ◽  
Vol 7 (1-2) ◽  
pp. 115-120
Author(s):  
Brigitta Zsótér ◽  
Ágnes Milojev
Keyword(s):  
Net Present Value ◽  
Research Work ◽  
The State ◽  
Point Of View ◽  
Bank Credit ◽  
Internal Rate Of Return ◽  
Present Value ◽  
Payback Time ◽  
Pig Farm ◽  
The Given

In our research work we aimed at carrying out an economical assessment of an investment and development of substantial volume. The examined project was completed at a pig-farm during which a new farrowing place and pig rearing building were built, as well as the renovation of the existing pig-farm. All of them were financed partly from the firm’s own source, partly from a non-repayable aid granted by the state, and finally from a credit granted by a commercial bank. The term of the credit is 10 years and the return of the investment expected by the investors is 8%, so we carried out our calculations according to these data. We examined the three possible ways of financing the investment from the economical point of view, as a result we proposed three hypotheses. Our hypotheses are: Hypothesis 1 (Case „A”): The investment will be financially recovered within the examined period of 10 years if it is financed from the firm’s own source, the state grant and the bank credit. Hypothesis 2 (Case „B”): The investment can be economically completed within the given period of time if the project meets the costs from the firm’s own source and the credit. Hypothesis 3 (Case „C”): The investment will be economically accomplished within the examined 10 years provided the firm finances the project from their own source and the state grant. In our calculations we used the net present value (NPV), the internal rate of return (IRR), the payback time (PB), the discounted payback time (DPB) and the profitability index (PI) as economy indicators. We carried out our calculations regarding 10 years to be able to compare the results since the term of the granted credit is 10 years, too.  

The physical properties of anomalous water

1971 ◽  
Vol 24 (4) ◽  
pp. 675 ◽  
Author(s):  
WW Mansfield
Keyword(s):  
Electrical Conductivity ◽  
Surface Tension ◽  
Melting Point ◽  
Aqueous Solutions ◽  
Physical Properties ◽  
Vapour Pressure ◽  
Column Length ◽  
Anomalous Water

The properties of anomalous aqueous condensates, prepared in the manner described by Deryagin,1 vary with aqueous vapour pressure. The changes of column length and of melting point are similar to those of ordinary aqueous solutions. There is no sound evidence that the condensate exhibits abnormal viscosity, density, electrical conductivity, or surface tension.

scholarly journals Scientific methods of public administration in migration research

2020 ◽  
Vol 68 (2) ◽  
pp. 109-122
Author(s):  
András László Szabó
Keyword(s):  
Public Administration ◽  
Research Methods ◽  
Methodological Approach ◽  
Point Of View ◽  
Scientific Methods ◽  
Migration Research ◽  
Independent Field ◽  
The Subject ◽  
The Given ◽  
Insight Into

In my study, I list the directions of migration research, all from the point of view of public administration science. The emergence of migration research as an independent field is necessitated by the growth of migration. Researchers are researching the phenomenon of migration from their own field. Public administration uses a multidisciplinary, i.e. methodological approach of several disciplines, all of which is determined by the knowledge and nature of the subject of the given research. In the following, I review and evaluate the methodological directions of the research, which can provide an answer to a segment of the phenomenon of migration. The study gives an insight into research methods for migration research. It is not intended to present specific examples and procedures. At the end of the study, in possible directions, beyond the science of public administration, I list the organizations and faculties that are able to use the methodology of migration research.

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