M. Antonov, E. Garcia-Sanchez, M. Hernandez-Rodriguez, J. Ivanisenko, L. Kommel, B. Omranpour, F. Sergejev
{"title":"Tailoring the microstructure and tribological properties in commercially pure aluminium processed by High Pressure Torsion Extrusion","authors":"M. Antonov, E. Garcia-Sanchez, M. Hernandez-Rodriguez, J. Ivanisenko, L. Kommel, B. Omranpour, F. Sergejev","doi":"10.3176/proc.2021.4.23","DOIUrl":"https://doi.org/10.3176/proc.2021.4.23","url":null,"abstract":"","PeriodicalId":54577,"journal":{"name":"Proceedings of the Estonian Academy of Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69932451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Gordeja, E. Kassaliete, G. Krumina, K. Panke, A. Petrova
{"title":"Accommodative response in various design soft contact lens wearers","authors":"A. Gordeja, E. Kassaliete, G. Krumina, K. Panke, A. Petrova","doi":"10.3176/proc.2021.4s.04","DOIUrl":"https://doi.org/10.3176/proc.2021.4s.04","url":null,"abstract":"","PeriodicalId":54577,"journal":{"name":"Proceedings of the Estonian Academy of Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69932566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
With the increasing complexity of the control systems, especially the systems with high safety requirements (such as aircraft, power systems, chemical facilities, nuclear energy facilities, etc.), the faulttolerant control strategies need to be used in order to ensure that the system can still meet a certain stable performance when an abnormality occurs. System integrity means that when one or more components in the system fail, the system can still work steadily by using the remaining components. In the early days, many scholars carried out research on this problem [1–3]. In 1971, Niederlinski proposed the concept of integral control [4], which is the idea of faulttolerant control. If the closedloop system is still stable and has ideal characteristics when the actuator, sensor or component fails, the closedloop control system is called the faulttolerant control system. Around 1980, Šiljak researched the problem of reliable stabilization of the system and published some results, which are the important early literature for the fault tolerant control [5–7]. Faults in the engineering system mainly include the actuator fault, sensor fault, controller fault and controlled object fault [8–11]. The actuator is the most prone to failure because it performs control tasks frequently. The failure of the actuator in the system may cause the system to lose its original performance, or even cause the system to become unstable [12–15]. For example, in spacecraft control systems, the actuators are one of the key components for precise control. If the actuator fails, it will inevitably affect the performance of the spacecraft control system. In serious cases, it may even lead to the failure of the space mission. Therefore, when the actuators fail, how Proceedings of the Estonian Academy of Sciences, 2021, 70, 1, 102–110
{"title":"Robust H∞ fault-tolerant control for stochastic Markov jump time-delay systems with actuator faults and application","authors":"F. Xingjian, P. Xinrui","doi":"10.3176/proc.2021.1.10","DOIUrl":"https://doi.org/10.3176/proc.2021.1.10","url":null,"abstract":"With the increasing complexity of the control systems, especially the systems with high safety requirements (such as aircraft, power systems, chemical facilities, nuclear energy facilities, etc.), the faulttolerant control strategies need to be used in order to ensure that the system can still meet a certain stable performance when an abnormality occurs. System integrity means that when one or more components in the system fail, the system can still work steadily by using the remaining components. In the early days, many scholars carried out research on this problem [1–3]. In 1971, Niederlinski proposed the concept of integral control [4], which is the idea of faulttolerant control. If the closedloop system is still stable and has ideal characteristics when the actuator, sensor or component fails, the closedloop control system is called the faulttolerant control system. Around 1980, Šiljak researched the problem of reliable stabilization of the system and published some results, which are the important early literature for the fault tolerant control [5–7]. Faults in the engineering system mainly include the actuator fault, sensor fault, controller fault and controlled object fault [8–11]. The actuator is the most prone to failure because it performs control tasks frequently. The failure of the actuator in the system may cause the system to lose its original performance, or even cause the system to become unstable [12–15]. For example, in spacecraft control systems, the actuators are one of the key components for precise control. If the actuator fails, it will inevitably affect the performance of the spacecraft control system. In serious cases, it may even lead to the failure of the space mission. Therefore, when the actuators fail, how Proceedings of the Estonian Academy of Sciences, 2021, 70, 1, 102–110","PeriodicalId":54577,"journal":{"name":"Proceedings of the Estonian Academy of Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69946671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Modern robot-integrated manufacturing cell according to the needs of Industry 4.0; pp. 407–412","authors":"T. Kangru, M. Moor, T. Otto, J. Riives, K. Vaher","doi":"10.3176/proc.2021.4.06","DOIUrl":"https://doi.org/10.3176/proc.2021.4.06","url":null,"abstract":"","PeriodicalId":54577,"journal":{"name":"Proceedings of the Estonian Academy of Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69932193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On (m, n)-semiprime submodules","authors":"A. Pekin, Suat Koç, Emel A. Ugurlu","doi":"10.3176/proc.2021.3.05","DOIUrl":"https://doi.org/10.3176/proc.2021.3.05","url":null,"abstract":"","PeriodicalId":54577,"journal":{"name":"Proceedings of the Estonian Academy of Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69932317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Juhani, M. Kolnes, J. Kübarsepp, M. Tarraste, M. Viljus
{"title":"In-situ alloying of TiC-FeCr cermets in manganese vapour","authors":"K. Juhani, M. Kolnes, J. Kübarsepp, M. Tarraste, M. Viljus","doi":"10.3176/proc.2021.4.22","DOIUrl":"https://doi.org/10.3176/proc.2021.4.22","url":null,"abstract":"","PeriodicalId":54577,"journal":{"name":"Proceedings of the Estonian Academy of Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69932397","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
. The Elements by a System of Transfer (EST) method offers exact solutions for various vibration problems of trusses, beams and frames. The method can be regarded as an improved or modified transfer matrix method where the roundoff errors generated by multiplying transfer arrays are avoided. It is assumed that in a steady state a bar/beam will vibrate with the circular frequency of a harmonic excitation force. The universal equation of elastic displacement (2nd/4th order differential equation) is described as a system of first order differential equations in matrix form. For the differential equations the compatibility conditions of a bar/beam element displacements at joint serve as essential boundary conditions. As the natural boundary conditions at joints, the equilibrium equations of elastic forces of bar/beam elements are considered. At the supports, restrictions to displacements (support conditions) have been applied. For steady-state forced vibration the phenomena of dynamic vibration absorption near the saddle points are observed and the response curves for displacement amplitude and elastic energy are calculated. The magnification factor at the excitation frequency is determined.
{"title":"Modified transfer matrix method for steady-state forced vibration: a system of bar elements","authors":"A. Lahe, Andres Braunbr¨uck, A. Klauson","doi":"10.3176/proc.2020.2.06","DOIUrl":"https://doi.org/10.3176/proc.2020.2.06","url":null,"abstract":". The Elements by a System of Transfer (EST) method offers exact solutions for various vibration problems of trusses, beams and frames. The method can be regarded as an improved or modified transfer matrix method where the roundoff errors generated by multiplying transfer arrays are avoided. It is assumed that in a steady state a bar/beam will vibrate with the circular frequency of a harmonic excitation force. The universal equation of elastic displacement (2nd/4th order differential equation) is described as a system of first order differential equations in matrix form. For the differential equations the compatibility conditions of a bar/beam element displacements at joint serve as essential boundary conditions. As the natural boundary conditions at joints, the equilibrium equations of elastic forces of bar/beam elements are considered. At the supports, restrictions to displacements (support conditions) have been applied. For steady-state forced vibration the phenomena of dynamic vibration absorption near the saddle points are observed and the response curves for displacement amplitude and elastic energy are calculated. The magnification factor at the excitation frequency is determined.","PeriodicalId":54577,"journal":{"name":"Proceedings of the Estonian Academy of Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69931197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Among different approaches to control the COVID-19 disease, there is clear interest to develop inhibitors which block the virus interaction with the host cells and through this simple mechanism could facilitate developing medication In this report, interaction of the virus SARS- CoV-2 spike protein S1 binding site with potential antiviral peptide ligands is analysed computationally The peptides are derived from the binding domain of the angiotensinconverting enzyme 2, which is the receptor site for this virus These calculations reveal that although shortening of these peptides from the N terminus and C terminus reduces their docking energy on the S1 binding site, there is still a number of peptides which effectively bind to the binding site on the SARS CoV2 spike protein S1, and thus can be used as leads for further optimization of the inhibitory effect Finally, this may open new perspectives for working out treatments against the virus infection (English) [ABSTRACT FROM AUTHOR] Arendusfaasis olevate erinevate COVID-19 ravivoimaluste hulgas eristub selge huvi inhibiitorite valjatootamise vastu, mis blokeerivad viiruse tungimist peremeesrakku ja holbustavad selle lihtsa mehhanismi kaudu haiguse ravi Sellest ideest lahtudes on kaesolevas toos uuritud SARS-CoV-2 teravikvalgul S1 asuva sidumistsentri omadusi, sest selle kaudu seostub see viirus raku pinnal asuva retseptorvalguga ACE2, millele jargneb viiruse RNA tungimine peremeesrakku Uuringuks vajalikud peptiidid (200 uhendit) konstrueeriti ACE2 struktuurist lahtudes ja nende jaoks arvutati dokkimise energia, mis kirjeldab nende seostumist viiruse teravikvalguga S1 Need arvutused naitavad, et juba uuritud peptiidide hulgas esineb mitmeid uhendeid, mis efektiivselt seonduvad teravikvalguga ja seega takistavad viiruse seondumist rakuga Saadud andmetest lahtudes on voimalik jatkata uurimistood peptiidide sidumise efektiivsuse edasiseks suurendamiseks, pidades silmas viirusinfektsioonivastaste ravimite loomise perspektiivi (Estonian) [ABSTRACT FROM AUTHOR] Copyright of Proceedings of the Estonian Academy of Sciences is the property of Teaduste Akadeemia Kirjastus and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission However, users may print, download, or email articles for individual use This abstract may be abridged No warranty is given about the accuracy of the copy Users should refer to the original published version of the material for the full abstract (Copyright applies to all Abstracts )
{"title":"Mapping of ACE2 binding site on SARS-CoV-2 spike protein S1: docking study with peptides","authors":"A. Kuznetsov, J. Järv","doi":"10.3176/proc.2020.3.06","DOIUrl":"https://doi.org/10.3176/proc.2020.3.06","url":null,"abstract":"Among different approaches to control the COVID-19 disease, there is clear interest to develop inhibitors which block the virus interaction with the host cells and through this simple mechanism could facilitate developing medication In this report, interaction of the virus SARS- CoV-2 spike protein S1 binding site with potential antiviral peptide ligands is analysed computationally The peptides are derived from the binding domain of the angiotensinconverting enzyme 2, which is the receptor site for this virus These calculations reveal that although shortening of these peptides from the N terminus and C terminus reduces their docking energy on the S1 binding site, there is still a number of peptides which effectively bind to the binding site on the SARS CoV2 spike protein S1, and thus can be used as leads for further optimization of the inhibitory effect Finally, this may open new perspectives for working out treatments against the virus infection (English) [ABSTRACT FROM AUTHOR] Arendusfaasis olevate erinevate COVID-19 ravivoimaluste hulgas eristub selge huvi inhibiitorite valjatootamise vastu, mis blokeerivad viiruse tungimist peremeesrakku ja holbustavad selle lihtsa mehhanismi kaudu haiguse ravi Sellest ideest lahtudes on kaesolevas toos uuritud SARS-CoV-2 teravikvalgul S1 asuva sidumistsentri omadusi, sest selle kaudu seostub see viirus raku pinnal asuva retseptorvalguga ACE2, millele jargneb viiruse RNA tungimine peremeesrakku Uuringuks vajalikud peptiidid (200 uhendit) konstrueeriti ACE2 struktuurist lahtudes ja nende jaoks arvutati dokkimise energia, mis kirjeldab nende seostumist viiruse teravikvalguga S1 Need arvutused naitavad, et juba uuritud peptiidide hulgas esineb mitmeid uhendeid, mis efektiivselt seonduvad teravikvalguga ja seega takistavad viiruse seondumist rakuga Saadud andmetest lahtudes on voimalik jatkata uurimistood peptiidide sidumise efektiivsuse edasiseks suurendamiseks, pidades silmas viirusinfektsioonivastaste ravimite loomise perspektiivi (Estonian) [ABSTRACT FROM AUTHOR] Copyright of Proceedings of the Estonian Academy of Sciences is the property of Teaduste Akadeemia Kirjastus and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission However, users may print, download, or email articles for individual use This abstract may be abridged No warranty is given about the accuracy of the copy Users should refer to the original published version of the material for the full abstract (Copyright applies to all Abstracts )","PeriodicalId":54577,"journal":{"name":"Proceedings of the Estonian Academy of Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69931805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Synthesis of molecular bromine in solventfree reaction was studied using two different reaction mixtures. The first mixture consisted of solid KNO3 and gaseous HBr, while the second setup used solid NaBr, KNO3 and gaseous HCl. Bromine formation was determined through bromination reaction of acetanilide, added into the reaction mixture, and monitored by the gas chromatography– mass spectrometry (GC–MS). It was found that this solventfree oxidative bromination technique could also be used for bromination of several other activated aromatic compounds but bromination of deactivated aromatics under the same condition was not successful, pointing to the need for a catalyst. The developed solventfree bromination method for aromatics has several benefits as there is no need for heating, the oxidizing agent is mild, and product purification procedure is simple. All mentioned features make this process quite perspective for synthetic applications.
{"title":"Solvent-free synthesis of molecular bromine and its application for in situ bromination of aromatic compounds","authors":"J. Järv, I. Rahu","doi":"10.3176/proc.2020.3.04","DOIUrl":"https://doi.org/10.3176/proc.2020.3.04","url":null,"abstract":"Synthesis of molecular bromine in solventfree reaction was studied using two different reaction mixtures. The first mixture consisted of solid KNO3 and gaseous HBr, while the second setup used solid NaBr, KNO3 and gaseous HCl. Bromine formation was determined through bromination reaction of acetanilide, added into the reaction mixture, and monitored by the gas chromatography– mass spectrometry (GC–MS). It was found that this solventfree oxidative bromination technique could also be used for bromination of several other activated aromatic compounds but bromination of deactivated aromatics under the same condition was not successful, pointing to the need for a catalyst. The developed solventfree bromination method for aromatics has several benefits as there is no need for heating, the oxidizing agent is mild, and product purification procedure is simple. All mentioned features make this process quite perspective for synthetic applications.","PeriodicalId":54577,"journal":{"name":"Proceedings of the Estonian Academy of Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69930926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Nordtest method evaluates the moisture buffer value (MBV) of materials that are being exposed to indoor air. The test simulates daily variations (high RH of 75% for 8 hours, low RH of 33% for 16 hours) in MBV, which in this context refers to the moisture uptake/release in the material when it is exposed to relative humidity (RH) in a square wave. We are looking for ways to increase clay plaster’s ability to buffer moisture. Which material has simultaneously a higher ability to buffer moisture and can be added to the clay plaster mixture? The recipe for the specimen included the following: waste paper (newspaper paper), glue (methylcellulose), clay and water. Our research showed that adding paper plaster mixture to the clay plaster mixture increases the moisture buffering ability of the plaster. The bigger the amount of added paper plaster, the better the plaster’s ability to buffer moisture.
{"title":"Adding waste paper to clay plaster to raise its ability to buffer moisture","authors":"A. Kubjas, L. Nei, N. Nutt","doi":"10.3176/proc.2020.3.01","DOIUrl":"https://doi.org/10.3176/proc.2020.3.01","url":null,"abstract":"The Nordtest method evaluates the moisture buffer value (MBV) of materials that are being exposed to indoor air. The test simulates daily variations (high RH of 75% for 8 hours, low RH of 33% for 16 hours) in MBV, which in this context refers to the moisture uptake/release in the material when it is exposed to relative humidity (RH) in a square wave. We are looking for ways to increase clay plaster’s ability to buffer moisture. Which material has simultaneously a higher ability to buffer moisture and can be added to the clay plaster mixture? The recipe for the specimen included the following: waste paper (newspaper paper), glue (methylcellulose), clay and water. Our research showed that adding paper plaster mixture to the clay plaster mixture increases the moisture buffering ability of the plaster. The bigger the amount of added paper plaster, the better the plaster’s ability to buffer moisture.","PeriodicalId":54577,"journal":{"name":"Proceedings of the Estonian Academy of Sciences","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69930910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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