Pub Date : 2023-11-06DOI: 10.24425/bpasts.2021.138971
GFA of the alloy [5‒7]. Furthermore, doping with Zr and Nb causes the microstructure refinement of the RE-Fe-B magnets and, thus, can enhance the magnetic properties of the annealed specimens [8‒10]. As was reported in [7], the appropriate setting of the composition for the Fe67Co9.4Nd3.1Dy0.5B20 alloy led to an improvement of the GFA that allowed processing of the fully glassy rods with diameters up to 0.5 mm. A further change of composition and addition of Zr facilitated casting 1-mm diameter amorphous rods and up to 3-mm outer diameter tubes for the Fe61Co13.5Zr1Pr3.5Dy1B20 alloy [11]. However, a small amount of RE elements in the chemical composition caused the formation of a relatively low fraction of the RE2Fe14B phase. For this reason, such magnets reveal rather moderate magnetic parameters [12]. We have shown in our previous studies on rapidly solidified plates of various thicknesses produced for Pr9Fe50 + xCo13Zr1Nb4B23 – x (x = 0, 2, 5, 8) alloys that boron content greatly influences the GFA. In the case of the Pr9Fe50Co13Zr1Nb4B23 alloy, the 0.5-mm thick plates were fully amorphous while 1-mm plates were slightly crystalline and only one very low-intensity diffraction peak was detected [6, 13]. However, for alloys of lower B content, the suction cast plates were all crystalline in as-cast state. Furthermore, the critical cooling rate attainable for specific production equipment depends on the sample geometry [14]. The changes in the microstructure and magnetic properties with the sample shape were shown for the Pr9Fe52Co13Zr1Nb4B21 alloy [15]. The aim of the present work was to study the influence of the Fe to B ratio on the GFA as well as on the phase constitution, microstructure, and magnetic properties of the 1-mm diameter rods of Pr9Fe50 + xCo13Zr1Nb4B23 – x (x = 0, 5, 8) alloys in the as-cast state and those subjected to annealing. Preliminary analysis of magnetic parameters has shown that optimal magnetic
{"title":"Structure and properties of suction-cast Pr-(Fe, Co)-(Zr, Nb)-B rod magnets","authors":"","doi":"10.24425/bpasts.2021.138971","DOIUrl":"https://doi.org/10.24425/bpasts.2021.138971","url":null,"abstract":"GFA of the alloy [5‒7]. Furthermore, doping with Zr and Nb causes the microstructure refinement of the RE-Fe-B magnets and, thus, can enhance the magnetic properties of the annealed specimens [8‒10]. As was reported in [7], the appropriate setting of the composition for the Fe67Co9.4Nd3.1Dy0.5B20 alloy led to an improvement of the GFA that allowed processing of the fully glassy rods with diameters up to 0.5 mm. A further change of composition and addition of Zr facilitated casting 1-mm diameter amorphous rods and up to 3-mm outer diameter tubes for the Fe61Co13.5Zr1Pr3.5Dy1B20 alloy [11]. However, a small amount of RE elements in the chemical composition caused the formation of a relatively low fraction of the RE2Fe14B phase. For this reason, such magnets reveal rather moderate magnetic parameters [12]. We have shown in our previous studies on rapidly solidified plates of various thicknesses produced for Pr9Fe50 + xCo13Zr1Nb4B23 – x (x = 0, 2, 5, 8) alloys that boron content greatly influences the GFA. In the case of the Pr9Fe50Co13Zr1Nb4B23 alloy, the 0.5-mm thick plates were fully amorphous while 1-mm plates were slightly crystalline and only one very low-intensity diffraction peak was detected [6, 13]. However, for alloys of lower B content, the suction cast plates were all crystalline in as-cast state. Furthermore, the critical cooling rate attainable for specific production equipment depends on the sample geometry [14]. The changes in the microstructure and magnetic properties with the sample shape were shown for the Pr9Fe52Co13Zr1Nb4B21 alloy [15]. The aim of the present work was to study the influence of the Fe to B ratio on the GFA as well as on the phase constitution, microstructure, and magnetic properties of the 1-mm diameter rods of Pr9Fe50 + xCo13Zr1Nb4B23 – x (x = 0, 5, 8) alloys in the as-cast state and those subjected to annealing. Preliminary analysis of magnetic parameters has shown that optimal magnetic","PeriodicalId":55299,"journal":{"name":"Bulletin of the Polish Academy of Sciences-Technical Sciences","volume":"218 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135679937","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-06DOI: 10.24425/BPASTS.2019.130891
T. Kaczorek
The Drazin inverse of matrices is applied to analysis of the pointwise completeness and of the pointwise degeneracy of the fractional descriptor linear discrete-time systems. Necessary and sufficient conditions for the pointwise completeness and the pointwise degeneracy of the fractional descriptor linear discrete-time systems are established. It is shown that every fractional descriptor linear discrete-time systems is not pointwise complete and it is pointwise degenerated in one step (for i = 1).
{"title":"The pointwise completeness and the pointwise degeneracy of fractional descriptor discrete-time linear systems","authors":"T. Kaczorek","doi":"10.24425/BPASTS.2019.130891","DOIUrl":"https://doi.org/10.24425/BPASTS.2019.130891","url":null,"abstract":"The Drazin inverse of matrices is applied to analysis of the pointwise completeness and of the pointwise degeneracy of the fractional descriptor linear discrete-time systems. Necessary and sufficient conditions for the pointwise completeness and the pointwise degeneracy of the fractional descriptor linear discrete-time systems are established. It is shown that every fractional descriptor linear discrete-time systems is not pointwise complete and it is pointwise degenerated in one step (for i = 1).","PeriodicalId":55299,"journal":{"name":"Bulletin of the Polish Academy of Sciences-Technical Sciences","volume":"1 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90508115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-06DOI: 10.24425/bpas.2018.125937
Xin Yang, D. Liu, Dake Zhou, S. Fei
Bull. Pol. Ac.: Tech. 66(6) 2018 Abstract. The traditional super-resolution (SR) reconstruction algorithm based on neighborhood embedding preserves the local geometric structure of image block manifold to reconstruct high-resolution (HR) manifold. However, when the magnification is large, the low resolution (LR) image is seriously degraded and most of the information is lost after down-sampling. The neighborhood relation of the LR manifold can not reflect the inherent data structure. In order to solve the problem effectively, we propose a face image SR algorithm based on pre-amplification non-negative restricted neighborhood embedding. In the training phase, the LR image is pre-amplified so that there are more similar manifold structures between the HR and LR resolution images. The constraints of the reconstructed coefficients are loosened and the HR image blocks are iteratively updated to obtain the reconstructed weights. The experimental results show that the proposed method has a better reconstruction effect compared with some traditional learning algorithms.
{"title":"Super-resolution reconstruction of face images based on pre-amplification non-negative restricted neighborhood embedding","authors":"Xin Yang, D. Liu, Dake Zhou, S. Fei","doi":"10.24425/bpas.2018.125937","DOIUrl":"https://doi.org/10.24425/bpas.2018.125937","url":null,"abstract":"Bull. Pol. Ac.: Tech. 66(6) 2018 Abstract. The traditional super-resolution (SR) reconstruction algorithm based on neighborhood embedding preserves the local geometric structure of image block manifold to reconstruct high-resolution (HR) manifold. However, when the magnification is large, the low resolution (LR) image is seriously degraded and most of the information is lost after down-sampling. The neighborhood relation of the LR manifold can not reflect the inherent data structure. In order to solve the problem effectively, we propose a face image SR algorithm based on pre-amplification non-negative restricted neighborhood embedding. In the training phase, the LR image is pre-amplified so that there are more similar manifold structures between the HR and LR resolution images. The constraints of the reconstructed coefficients are loosened and the HR image blocks are iteratively updated to obtain the reconstructed weights. The experimental results show that the proposed method has a better reconstruction effect compared with some traditional learning algorithms.","PeriodicalId":55299,"journal":{"name":"Bulletin of the Polish Academy of Sciences-Technical Sciences","volume":"47 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90616611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-06DOI: 10.24425/BPASTS.2020.134663
M. Siwczyński, M. Jaraczewski
Commonly known DC-AC switching converters are commonly used in compensator branches. One example of this is a static synchronous compensator (STATCOM). It consists of a voltage source converter (VSC) and acts as an inverter with a capacitor as a DC power source. These compensators use the PWM switching scheme or space vector modulation (SVM) method. Both methods require the desired signal to be generated. In some cases, as during the synthesis of self-excited systems or active energy-compensators, it is necessary to perform the desired branch immittance, e.g. negative capacitance, inductance, resistance or irrational impedance. In such cases, it is necessary to control the universal branch on the basis of a formula. This article presents the implementation method for the convolutional type impedance operators.
{"title":"Active-controlled two-terminal network implementing a convolution-type immittance operator","authors":"M. Siwczyński, M. Jaraczewski","doi":"10.24425/BPASTS.2020.134663","DOIUrl":"https://doi.org/10.24425/BPASTS.2020.134663","url":null,"abstract":"Commonly known DC-AC switching converters are commonly used in compensator branches. One example of this is a static synchronous compensator (STATCOM). It consists of a voltage source converter (VSC) and acts as an inverter with a capacitor as a DC power source. These compensators use the PWM switching scheme or space vector modulation (SVM) method. Both methods require the desired signal to be generated. In some cases, as during the synthesis of self-excited systems or active energy-compensators, it is necessary to perform the desired branch immittance, e.g. negative capacitance, inductance, resistance or irrational impedance. In such cases, it is necessary to control the universal branch on the basis of a formula. This article presents the implementation method for the convolutional type impedance operators.","PeriodicalId":55299,"journal":{"name":"Bulletin of the Polish Academy of Sciences-Technical Sciences","volume":"13 6","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72620131","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-06DOI: 10.24425/BPASTS.2020.135377
P. Marchel, J. Paska, K. Pawlak, Krzysztof Zagrajek
Hybrid Power Sources/Systems (HPS) are generally treated as local prosumer supplies. The paper presents a new approach to the strategy of electricity contracting from HPS, considering hybrid systems as a new type of quasi-centrally dispatched power units operating in Polish market conditions. The possibilities of contracting electricity from HPS, consisting of three electricity generation technologies: biogas plant, wind power plant and solar power plant, are presented. The opportunity to obtain additional income from the electricity trading on the balancing market was used. Proposals for a new mathematical description of HPS topology were also presented, including a feasibility function, which can be used for technical and economic analyses. The obtained results can be used as a direction of development in the field of optimization of hybrid source operation in cooperation with the power grid. Based on the conducted analyses, it can be observed that electricity sales contracts concluded for each hour of the day may bring additional profit for the investor. However, the strong dependence of the proposed strategy on the situation on the balancing market or other local electricity markets similar in their operations should be emphasized.
{"title":"A practical approach to optimal strategies of electricity contracting from Hybrid Power Sources","authors":"P. Marchel, J. Paska, K. Pawlak, Krzysztof Zagrajek","doi":"10.24425/BPASTS.2020.135377","DOIUrl":"https://doi.org/10.24425/BPASTS.2020.135377","url":null,"abstract":"Hybrid Power Sources/Systems (HPS) are generally treated as local prosumer supplies. The paper presents a new approach to the strategy of electricity contracting from HPS, considering hybrid systems as a new type of quasi-centrally dispatched power units operating in Polish market conditions. The possibilities of contracting electricity from HPS, consisting of three electricity generation technologies: biogas plant, wind power plant and solar power plant, are presented. The opportunity to obtain additional income from the electricity trading on the balancing market was used. Proposals for a new mathematical description of HPS topology were also presented, including a feasibility function, which can be used for technical and economic analyses. The obtained results can be used as a direction of development in the field of optimization of hybrid source operation in cooperation with the power grid. Based on the conducted analyses, it can be observed that electricity sales contracts concluded for each hour of the day may bring additional profit for the investor. However, the strong dependence of the proposed strategy on the situation on the balancing market or other local electricity markets similar in their operations should be emphasized.","PeriodicalId":55299,"journal":{"name":"Bulletin of the Polish Academy of Sciences-Technical Sciences","volume":"18 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74524972","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-06DOI: 10.24425/BPASTS.2019.131568
Przemysław Trochimiuk, M. Zdanowski, J. Rąbkowski
. This paper discusses selected problems regarding a high-frequency improved current-fed quasi-Z-source inverter (iCFqZSI) designed and built with SiC power devices. At first, new, modified topology of the impedance network is presented. As the structure is derived from the series connection of two networks, the voltage stress across the SiC diodes and the inductors is reduced by a factor of two. Therefore, the SiC MOSFETs may be switched with frequencies above 100 kHz and volume and weight of the passive components is decreased. Furthermore, additional leg with two SiC MOSFETs working as a bidirectional switch is added to limit the current stress during the short-through states. In order to verify the performance of the proposed solution a 6 kVA laboratory model was designed to connect a 400 V DC source (battery) and a 3 £ 400 V grid. According to presented simulations and experimental results high-frequency iCFqZSI is bidirectional – it may act as an inverter, but also as a rectifier. Performed measurements show correct operation at switching frequency of 100 kHz, high quality of the input and output waveforms is observed. The additional leg increases efficiency by up to 0.6% – peak value is 97.8%.
{"title":"Current-fed quasi-Z-source H7 inverter with reduced stress on SiC power devices","authors":"Przemysław Trochimiuk, M. Zdanowski, J. Rąbkowski","doi":"10.24425/BPASTS.2019.131568","DOIUrl":"https://doi.org/10.24425/BPASTS.2019.131568","url":null,"abstract":". This paper discusses selected problems regarding a high-frequency improved current-fed quasi-Z-source inverter (iCFqZSI) designed and built with SiC power devices. At first, new, modified topology of the impedance network is presented. As the structure is derived from the series connection of two networks, the voltage stress across the SiC diodes and the inductors is reduced by a factor of two. Therefore, the SiC MOSFETs may be switched with frequencies above 100 kHz and volume and weight of the passive components is decreased. Furthermore, additional leg with two SiC MOSFETs working as a bidirectional switch is added to limit the current stress during the short-through states. In order to verify the performance of the proposed solution a 6 kVA laboratory model was designed to connect a 400 V DC source (battery) and a 3 £ 400 V grid. According to presented simulations and experimental results high-frequency iCFqZSI is bidirectional – it may act as an inverter, but also as a rectifier. Performed measurements show correct operation at switching frequency of 100 kHz, high quality of the input and output waveforms is observed. The additional leg increases efficiency by up to 0.6% – peak value is 97.8%.","PeriodicalId":55299,"journal":{"name":"Bulletin of the Polish Academy of Sciences-Technical Sciences","volume":"35 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77957114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-06DOI: 10.24425/BPAS.2019.127337
T. Kaczorek
. The global (absolute) stability of nonlinear systems with negative feedbacks and positive descriptor linear parts is addressed. Transfer matrices of positive descriptor linear systems are analyzed. The characteristics u = f ( e ) of the nonlinear parts satisfy the condition k 1 e ∙ f ( e ) ∙ k 2 e for some positive k 1 , k 2 . It is shown that the nonlinear feedback systems are globally asymptotically stable if the Nyquist plots of the positive descriptor linear parts are located in the right-hand side of the circles
． 研究了具有负反馈和正广义线性部分的非线性系统的全局(绝对)稳定性问题。分析了正广义线性系统的转移矩阵。非线性部分的特性u = f (e)满足k 1 e∙f (e)∙k 2 e对某正k 1, k 2的条件。证明了如果正描述子线性部分的Nyquist图位于圆的右侧，则非线性反馈系统是全局渐近稳定的
{"title":"Global stability of nonlinear feedback systemswith positive descriptor linear parts","authors":"T. Kaczorek","doi":"10.24425/BPAS.2019.127337","DOIUrl":"https://doi.org/10.24425/BPAS.2019.127337","url":null,"abstract":". The global (absolute) stability of nonlinear systems with negative feedbacks and positive descriptor linear parts is addressed. Transfer matrices of positive descriptor linear systems are analyzed. The characteristics u = f ( e ) of the nonlinear parts satisfy the condition k 1 e ∙ f ( e ) ∙ k 2 e for some positive k 1 , k 2 . It is shown that the nonlinear feedback systems are globally asymptotically stable if the Nyquist plots of the positive descriptor linear parts are located in the right-hand side of the circles","PeriodicalId":55299,"journal":{"name":"Bulletin of the Polish Academy of Sciences-Technical Sciences","volume":"10 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77972054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-06DOI: 10.24425/BPASTS.2020.133118
A. Tlija, K. Wegrzyn-Wolska, D. Istrate
The objective of this work is to set up a methodology that considers missing data from a connected heartbeat sensor in order to propose a good replacement methodology in the context of heart rate variability (HRV) computation. The framework is a research project, which aims to build a system that can measure stress and other factors influencing the onset and development of heart disease. The research encompasses studying existing methods, and improving them by use of experimental data from case study that describe the participant’s everyday life. We conduct a study to modelize stress from the HRV signal, which is extracted from a heart rate monitor belt connected to a smart watch. This paper describes data recording procedure and data imputation methodology. Missing data is a topic that has been discussed by several authors. The manuscript explains why we choose spline interpolation for data values imputation. We implement a random suppression data procedure and simulate removed data. After that, we implement several algorithms and choose the best one for our case study based on the mean square error.
{"title":"Missing-data imputation using wearable sensors in heart rate variability","authors":"A. Tlija, K. Wegrzyn-Wolska, D. Istrate","doi":"10.24425/BPASTS.2020.133118","DOIUrl":"https://doi.org/10.24425/BPASTS.2020.133118","url":null,"abstract":"The objective of this work is to set up a methodology that considers missing data from a connected heartbeat sensor in order to propose a good replacement methodology in the context of heart rate variability (HRV) computation. The framework is a research project, which aims to build a system that can measure stress and other factors influencing the onset and development of heart disease. The research encompasses studying existing methods, and improving them by use of experimental data from case study that describe the participant’s everyday life. We conduct a study to modelize stress from the HRV signal, which is extracted from a heart rate monitor belt connected to a smart watch. This paper describes data recording procedure and data imputation methodology. Missing data is a topic that has been discussed by several authors. The manuscript explains why we choose spline interpolation for data values imputation. We implement a random suppression data procedure and simulate removed data. After that, we implement several algorithms and choose the best one for our case study based on the mean square error.","PeriodicalId":55299,"journal":{"name":"Bulletin of the Polish Academy of Sciences-Technical Sciences","volume":"46 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79621227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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