Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 25
items per page: 25 50 75
Sort by:
Download PDF Download RIS Download Bibtex

Abstract

It is well known that the magnitudes of the coefficients of the discrete Fourier transform (DFT) are invariant under certain operations on the input data. In this paper, the effects of rearranging the elements of an input data on its DFT are studied. In the one-dimensional case, the effects of permuting the elements of a finite sequence of length N on its discrete Fourier transform (DFT) coefficients are investigated. The permutations that leave the unordered collection of Fourier coefficients and their magnitudes invariant are completely characterized. Conditions under which two different permutations give the same DFT coefficient magnitudes are given. The characterizations are based on the automorphism group of the additive group ZN of integers modulo N and the group of translations of ZN. As an application of the results presented, a generalization of the theorem characterizing all permutations that commute with the discrete Fourier transform is given. Numerical examples illustrate the obtained results. Possible generalizations and open problems are discussed. In higher dimensions, results on the effects of certain geometric transformations of an input data array on its DFT are given and illustrated with an example.

Go to article

Authors and Affiliations

S. Hui
S.H. Żak
Download PDF Download RIS Download Bibtex

Abstract

The discrete Fourier transform (DFT) is the main method of electrical harmonic analysis since it’s easily realized in an embedded system. But there were some difficulties in performing synchronized sampling. The spectral leakage caused by asynchronous sampling affects the accuracy of harmonics analysis. Using window functions and interpolation algorithms can improve the accuracy of harmonics analysis. An approach for electrical harmonic analysis based on the interpolation DFT was proposed. A window function reduces DFT leakage and the interpolation algorithm modifies the calculation results of frequency, amplitude and the initial phase angle. The simulation results indicate that, by using the interpolation DFT electrical harmonic analysis method based on the Hanning window or the Blackman window, the error of calculating amplitudes and frequencies is not greater than 0.5%.
Go to article

Authors and Affiliations

Lina Jiao
1
ORCID: ORCID
Yang Du
1

  1. Shandong Polytechnic, China
Download PDF Download RIS Download Bibtex

Abstract

This paper presents a universal approximation of the unit circle by a polygon that can be used in signal processing algorithms. Optimal choice of the values of three parameters of this approximation allows one to obtain a high accuracy of approximation. The approximation described in the paper has a universal character and can be used in many signal processing algorithms, such as DFT, that use the mathematical form of the unit circle. One of the applications of the described approximation is the DFT linear interpolation method (LIDFT). Applying the results of the presented paper to improve the LIDFT method allows one to significantly decrease the errors in estimating the amplitudes and frequencies of multifrequency signal components. The paper presents the derived formulas, an analysis of the approximation accuracy and the region of best values for the approximation parameters.

Go to article

Authors and Affiliations

Józef Borkowski
Download PDF Download RIS Download Bibtex

Abstract

To improve the estimation of active power, the possibility of estimating the amplitude square of a signal component using the interpolation of the squared amplitude discrete Fourier transform (DFT) coefficients is presented. As with an energy-based approach, the amplitude square can be estimated with the squared amplitude DFT coefficients around the component peak and a suitable interpolation algorithm. The use of the Hann window, for which the frequency spectrum is well known, and the three largest local amplitude DFT coefficients gives lower systematic errors in squared interpolated approach or in better interpolated squared approach than the energy-based approach, although the frequency has to be estimated in the first step. All investigated algorithms have almost the same noise propagation and the standard deviations are about two times larger than the Cramér-Rao lower bound.

Go to article

Authors and Affiliations

Tomaž Lušin
Dušan Agrež
Download PDF Download RIS Download Bibtex

Abstract

In this work, a highly effective catalyst (MoO3) is synthesized and applied for catalytic wet air oxidation (CWAO) treatment of pharmaceutical wastewater. The catalyst is systematically characterized to investigate the morphology, crystal structure and chemical composition, and the findings demostrated that MoO3 catalyst is successfully synthesized. The degradation mechanism is also illustrated by the density functional theory (DFT) calculation. The degradation experiments confirm that MoO3 catalyst exhibits excellent catalytic performance in CWAO, and the removal rate of TOC (Total Organic Carbon) and COD (Chemical Oxygen Demand) is achieved to more than 93%. The catalyst doses, reaction temperature and reaction time have a significant impact on the removal of pollutants. The degradation process of pollutants in CWAO could be satisfactorily fitted by the second-order kinetics. Besides, MoO3 displays a favorable stability as CWAO catalyst. DFT calculation illustrates that MoO3 catalyst is a typical indirect band gap semiconductor. Moreover, the high temperature environment provides the thermal excitation energy, which favors to the free electrons nearing Fermi level to escape the material surface, and excites them to the conduction band, then directly reduces the pollutants in CWAO. These findings demonstrate that MoO3 can be used as an efficient and excellent catalyst for CWAO of pharmaceutical wastewater.
Go to article

Bibliography

  1. Ahsani, M., Hazrati, H., Javadi, M., Ulbricht, M., & Yegani, R. (2020). Preparation of antibiofouling nanocomposite PVDF/Ag-SiO2 membrane and long-term performance evaluation in the MBR system fed by real pharmaceutical wastewater. Separation and Purification Technology, 249,116938. DOI: 10.1016/j.seppur.2020.116938
  2. Aniszewski, A. (2020). Impact of ground adsorption capacity on he change on the chemical composition of groundwater. Archives of Environmental Protection, 46,2, pp. 35-41. DOI: 10.24425/aep.2020.133472
  3. Chen, C., Cheng, T., Shi, Y., & Tian, Y. (2014a). Adsorption of Cu(II) from Aqueous Solution on Fly Ash Based Linde F (K) Zeolite. Iranian Journal of Chemistry & Chemical Engineering-International English Edition, 33,3, pp. 29-35. DOI: 10.30492/IJCCE.2014.11328
  4. Chen, C., Cheng, T., Wang, Z. L., & Han, C. H. (2014b). Removal of Zn2+ in aqueous solution by Linde F (K) zeolite prepared from recycled fly ash. Journal of the Indian Chemical Society 91,2, pp. 285-291 https://www.researchgate.net/publication/295591718_Removal_of_Zn2_in_aqueous_solution_by_Linde_F_K_zeolite_prepared_from_recycled_fly_ash
  5. Chen, C., Cheng, T., Zhang, X., Wu, R., & Wang, Q. (2019a). Synthesis of an Efficient Pb Adsorption Nano-Crystal under Strong Alkali Hydrothermal Environment Using a Gemini Surfactant as Directing Agent. Journal of the Chemical Society of Pakistan, 41,6, pp. 1034-1038.
  6. Chen, C., Chenhao, Y., Ting, C., Xiao, Z., & Jiandong, Z. (2019b). Preparation of Mo-Na composite catalyst and its application in pharmaceutical wastewater treatment. Industrial Water Treatment 39,8, pp. 77-81.(in Chinese)
  7. Chen, C., Jiandong, Z., Ting, C., & Xiao, Z. (2018). Preparation of Nano-manganese Cerium/γ-Al2O3 Composite Catalyst and Its Catalytic Wet Air Oxidation Treatment of Antibiotic Production Wastewater. Journal of Synthetic Crystals 47,11, pp. 2288-2294. (in Chinese)
  8. Chen, C., Li, Q., Shen, L., & Zhai, J. (2012). Feasibility of manufacturing geopolymer bricks using circulating fluidized bed combustion bottom ash. Environ Technol 33,10-12, pp. 1313-1321. DOI: 10.1080/09593330.2011.626797
  9. Chen, M., Ren, L., Qi, K., Li, Q., Lai, M., Li, Y., Li, X., & Wang, Z. (2020). Enhanced removal of pharmaceuticals and personal care products from real municipal wastewater using an electrochemical membrane bioreactor. Bioresource Technology, 311,123579. DOI: 10.1016/j.biortech.2020.123579
  10. Cheng, T., Chen, C., Tang, R., Han, C.-H., & Tian, Y. (2018). Competitive Adsorption of Cu, Ni, Pb, and Cd from Aqueous Solution Onto Fly Ash-Based Linde F(K) Zeolite. Iranian Journal of Chemistry & Chemical Engineering-International English Edition, 37,1, pp. 61-72. DOI: 10.30492/IJCCE.2018.31971
  11. Cheng, T., Chen, C., Wang, L., Zhang, X., Ye, C., Deng, Q., & Chen, G. (2021). Synthesis of Fly Ash Magnetic Glass Microsphere@BiVO4 and Its Hybrid Action of Visible-Light Photocatalysis and Adsorption Process. Polish Journal of Environmental Studies, 30,3, pp. 1-14. DOI: 10.15244/pjoes/127918
  12. Coimbra, R. N., Calisto, V., Ferreira, C. I. A., Esteves, V. I., & Otero, M. (2019). Removal of pharmaceuticals from municipal wastewater by adsorption onto pyrolyzed pulp mill sludge. Arabian Journal of Chemistry, 12,8, pp. 3611-3620. DOI: 10.1016/j.arabjc.2015.12.001
  13. Dong, S., Cui, L., Zhang, W., Xia, L., & Sun, J. J. C. E. J. (2020). Double-shelled ZnSnO3 hollow cubes for efficient photocatalytic degradation of antibiotic wastewater. Chemical engineering journal 384,123279. DOI: 10.1016/j.cej.2019.123279
  14. Ferrer-Polonio, E., Fernandez-Navarro, J., Iborra-Clar, M.-I., Alcaina-Miranda, M.-I., & Antonio Mendoza-Roca, J. (2020). Removal of pharmaceutical compounds commonly-found in wastewater through a hybrid biological and adsorption process. Journal of Environmental Management 33,3, pp. 29-35. DOI: 10.1016/j.jenvman.2020.110368
  15. Guo, J., Fortunato, L., Deka, B. J., Jeong, S., & An, A. K. (2020). Elucidating the fouling mechanism in pharmaceutical wastewater treatment by membrane distillation. Desalination, 475,114148. DOI: 10.1016/j.desal.2019.114148
  16. He, Y., Chen, Y.-g., Zhang, K.-n., Ye, W.-m., & Wu, D.-y. (2019). Removal of chromium and strontium from aqueous solutions by adsorption on laterite. Archives of Environmental Protection, 45,3, pp. 11-20. DOI 10.24425/aep.2019.128636
  17. Hofman-Caris, C. H. M., Siegers, W. G., van de Merlen, K., de Man, A. W. A., & Hofman, J. A. M. H. (2017). Removal of pharmaceuticals from WWTP effluent: Removal of EfOM followed by advanced oxidation. Chemical Engineering Journal, 327,1, pp. 514-521. DOI: 10.1016/j.cej.2017.06.154
  18. Hohenberg, P. & Kohn, W. (1964). InhomogeIIeous Electron Gas. Physical Review, 136,3B, pp. 864-871
  19. Huang, J., Wang, X., Li, S. & Wang, Y. (2010). ZnO/MoO3 mixed oxide nanotube: A highly efficient and stable catalyst for degradation of dye by air under room conditions. Applied Surface Science, 257,1, pp. 116-121. DOI: 10.1016/j.apsusc.2010.06.046
  20. Huang, P. R., He, Y., Cao, C. & Lu, Z. H. (2014). Impact of lattice distortion and electron doping on alpha-MoO3 electronic structure. Sci Rep. 4,7131, pp. 1-7. DOI: 10.1038/srep07131
  21. Kang, J., Zhan, W., Li, D., Wang, X., Song, J. & Liu, D. (2011). Integrated catalytic wet air oxidation and biological treatment of wastewater from Vitamin B-6 production. Physics and Chemistry of the Earth, 36,9-11, pp. 455-458. DOI: 10.1016/j.pce.2010.03.043
  22. Khan, A. H., Khan, N. A., Ahmed, S., Dhingra, A., Singh, C. P., Khan, S. U., Mohammadi, A. A., Changani, F., Yousefi, M., Alam, S., Vambol, S., Vambol, V., Khursheed, A. & Ali, I. (2020). Application of advanced oxidation processes followed by different treatment technologies for hospital wastewater treatment. Journal of Cleaner Production, 269,122411. DOI: 10.1016/j.jclepro.2020.122411
  23. Klancar, A., Trontelj, J., Kristl, A., Meglic, A., Rozina, T., Justin, M. Z. & Roskar, R. (2016). An advanced oxidation process for wastewater treatment to reduce the ecological burden from pharmacotherapy and the agricultural use of pesticides. Ecological Engineering, 97,186-195. DOI: 10.1016/j.ecoleng.2016.09.010
  24. Kohn, W. & Sham, L. J. (1965). Self-Consistent Equations Including Exchange and Correlation Effects. Physical Review, 140, A1133.
  25. Kresse, & Furthmuller (1996). Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Physical review. B, Condensed matter 54,16, pp. 11169-11186
  26. Li, W., Zhao, S., Qi, B., Du, Y., Wang, X. & Huo, M. (2009). Fast catalytic degradation of organic dye with air and MoO3:Ce nanofibers under room condition. Applied Catalysis B-Environmental, 92,3-4, pp. 333-340. DOI: 10.1016/j.apcatb.2009.08.012
  27. Li, Y., Shen, J., Quan, W., Diao, Y., Wu, M., Zhang, B., Wang, Y., & Yang, D. (2020). 2D/2D p-n Heterojunctions of CaSb2O6/g-C(3)N(4)for Visible Light-Driven Photocatalytic Degradation of Tetracycline. European Journal of Inorganic Chemistry, 2020,40, pp. 3852-3858. DOI: 10.1002/ejic.202000635
  28. Tan, l., Yu, C., Wang, M., Zhang, S. & Sun, J., Dang, S. & Sun, J. (2019). Synergistic effect of adsorption and photocatalysis of 3D g-C3N4-agar hybrid aerogels. Applaied Surface Science, 467-468, pp. 286-292. DOI: 10.1016/j.apsusc.2018.10.067
  29. Lunagomez Rocha, M. A., Del Angel, G., Torres-Torres, G., Cervantes, A., Vazquez, A., Arrieta, A. & Beltramini, J. N. (2015). Effect of the Pt oxidation state and Ce3+/Ce4+ ratio on the Pt/TiO2-CeO2 catalysts in the phenol degradation by catalytic wet air oxidation (CWAO). Catalysis Today 250,145-154. DOI: 10.1016/j.cattod.2014.09.016
  30. Ma, Y., Jia, Y., Jiao, Z., Wang, L., Yang, M., Bi, Y. & Qi, Y. (2015). Facile synthesize α-MoO3 nanobelts with high adsorption property. Materials Letters, 157,53-56. DPOI: 10.1016/j.matlet.2015.05.095
  31. Mucha, Z. & Kułakowski, P. (2016). Turbidity measurements as a tool of monitoring and control of the SBR effluent at the small wastewater treatment plant – preliminary study. Archives of Environmental Protection, 42,3, pp. 33-36. DOI 10.1515/aep-2016-0030
  32. Mukimin, A., Vistanty, H. & Zen, N. (2020). Hybrid advanced oxidation process (HAOP) as highly efficient and powerful treatment for complete demineralization of antibiotics. Separation and Purification Technology, 241,116728. DOI: 10.1016/j.seppur.2020.116728
  33. Parvas, M., Haghighi, M. & Allahyari, S. (2019). Catalytic wet air oxidation of phenol over ultrasound-assisted synthesized Ni/CeO2-ZrO2 nanocatalyst used in wastewater treatment. Arabian Journal of Chemistry, 12,7, pp. 1298-1307. DOI: 10.1016/j.arabjc.2014.10.043
  34. Perdew, J., Burke, K. & Ernzerhof, M. (1996). Generalized Gradient Approximation Made Simple. Physical review letters, 77,3865-3868. DOI: 10.1103/PhysRevLett.77.3865
  35. Perdew, J., Chevary, J. A., H, V., Jackson, K., Pederson, M., Singh, D. & Fiolhais, C. (1992). Atoms, Molecules, Solids, and Surfaces: Applications of the Generalized Gradient Approximation for Exchange and Correlation. Physical review. B, Condensed matter, 46,6671-6687.
  36. Phoon, B. L., Ong, C. C., Saheed, M. S. M., Show, P.-L., Chang, J.-S., Ling, T. C., Lam, S. S. & Juan, J. C. (2020). Conventional and emerging technologies for removal of antibiotics from wastewater. Journal of Hazardous Materials, 400,122961. DOI: 10.1016/j.jhazmat.2020.122961
  37. Schrank, S. G., Jose, H. J., Moreira, R. F. P. M. & Schroder, H. F. (2004). Elucidation of the behavior of tannery wastewater under advanced oxidation conditions. Chemosphere, 56,5, pp. 411-23. DOI: 10.1016/j.chemosphere.2004.04.012
  38. Sushma, Kumari, M. & Saroha, A. K. (2018). Treatment of toxic industrial effluent containing nitrogenous organic compounds by integration of catalytic wet air oxidation at atmospheric pressure and biological processes. Journal of Environmental Chemical Engineering, 6,5, pp. 6256-6262. DOI:10.1016/j.jece.2018.09.057
  39. Urbanowska, A. & Kabsch-Korbutowicz, M. (2019). Nanofiltration as an effective method of NaOH recovery from regenerative solutions. Archives of Environmental Protection, 45,2, pp. 31-36. DOI: 10.24425/aep.2019.127978
  40. Verma, A., Kaur, H. & Dixit, D. (2013). Photocatalytic, Sonolytic and Sonophotocatalytic Degradation of 4-Chloro-2-Nitro Phenol. Archives of Environmental Protection, 39,2, pp. 17-28. DOI: 10.2478/aep-2013-0015
  41. Wang, G., Wang, D., Xu, Y., Li, Z. & Huang, L. (2020a). Study on optimization and performance of biological enhanced activated sludge process for pharmaceutical wastewater treatment. Science of the Total Environment, 739,140166. DOI:10.1016/j.scitotenv.2020.140166
  42. Wang, J., Dong, S., Yu, C., Han, X., Guo, J. & Sun, J. (2017). An efficient MoO3 catalyst for in-practical degradation of dye wastewater under room conditions. Catalysis Communications, 92,100-104. DOI: 10.1016/j.catcom.2017.01.013
  43. Wang, P., Liang, Y. N., Zhong, Z. & Hu, X. (2020b). Nano-hybrid bimetallic Au-Pd catalysts for ambient condition-catalytic wet air oxidation (AC-CWAO) of organic dyes. Separation and Purification Technology, 233,15, pp. 11590. DOI: 10.1016/j.seppur.2019.115960
  44. Xu, K., Liao, N., Zheng, B. & Zhou, H. (2020). Adsorption and diffusion behaviors of H2, H2S, NH3, CO and H2O gases molecules on MoO3 monolayer: A DFT study. Physics Letters A, 384,21, pp. 1-5. DOI: 10.1016/j.physleta.2020.126533
  45. Yadav, A., Teja, A. K. & Verma, N. (2016). Removal of phenol from water by catalytic wet air oxidation using carbon bead – supported iron nanoparticle – containing carbon nanofibers in an especially configured reactor. Journal of Environmental Chemical Engineering, 4,2, pp. 1504-1513. DOI: 10.1016/j.jece.2016.02.021
  46. Zhang, X., Cheng, T., Chen, C., Wang, L., Deng, Q., Chen, G. & Ye, C. (2020). Synthesis of a novel magnetic nano-zeolite and its application as an efficient heavy metal adsorbent. Materials Research Express, 7,8, pp. 085007. DOI: 10.1088/2053-1591/abab43
  47. Zhang, Y., Zhang, Z., Yan, Q. & Wang, Q. (2016). Synthesis, characterization, and catalytic activity of alkali metal molybdate/α-MoO3 hybrids as highly efficient catalytic wet air oxidation catalysts. Applied Catalysis A: General, 511,47-58. DOI: 10.1016/j.apcata.2015.11.035
  48. Zou, H., Ma, W. & Wang, Y. (2015). A novel process of dye wastewater treatment by linking advanced chemical oxidation with biological oxidation. Archives of Environmental Protection, 41,4, pp. 33-39. DOI: 10.1515/aep-2015-0037
Go to article

Authors and Affiliations

Chen Chen
1
Ting Cheng
2
Lei Wang
1
ORCID: ORCID
Yuan Tian
1
Qin Deng
1
Yisu Shi
1

  1. School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, China
  2. School of Environmental Ecology, Jiangsu City Vocational College, China
Download PDF Download RIS Download Bibtex

Abstract

The discrete Fourier transform (DFT) is a principal method for power system harmonic analysis. The fundamental frequency of the power system increases or decreases following load changes during normal operation. It is difficult to achieve synchronous sampling and integer period truncation in power harmonic analysis. The resulting spectrum leakage affects the accuracy of the measurement results. For this reason, a windowed interpolation DFT method for power system harmonic analysis to reduce errors was presented in this paper. First, the frequency domain expression of the windowed signal Fourier transform is analyzed. Then, the magnitude of the three discrete spectrum lines near the harmonic frequency point is used to determine the accurate position of the harmonic spectrum. Then, the calculation of the amplitude, frequency, and phase of harmonics is presented. The tripleline interpolation DFT can improve the accuracy of electrical harmonic analysis. Based on the algorithm, the practical rectification formulas were obtained by using the polynomial approximation method. The simulation results show that the fast attenuation of window function sidelobe is the key to reduce the error. The triple-line interpolation DFT based on Hanning, Blackman, Nuttall 3-Term windows has higher calculation accuracy, which can meet the requirements of electrical harmonic analysis.
Go to article

Bibliography

[1] Schlabbach J., Blume D., Stephanblome T., Voltage quality in electrical power systems, The Institution of Engineering and Technology (2001).
[2] Yudaev I.V., Rud E.V., Yundin M.A., Ponomarenko T.Z., Isupova A.M., Analysis of the harmonic composition of current in the zero-working wire at the input of the load node with the prevailing non-linear power consumers, Archives of Electrical Engineering, vol. 70, no. 2, pp. 463–473 (2021), DOI: 10.24425/aee.2021.136996.
[3] Short T., Electric Power Distribution Handbook, Second Edition, CRC Press (2014).
[4] IEC 61000-4-30, Testing and measurement techniques-Power quality measurement methods (2008).
[5] IEC 61000-4-7, Testing and measurement techniques-General guide on harmonics and interharmonics measurements and instrumentation, for power supply systems and equipment connected thereto (2009).
[6] Jos Arrillaga, Neville R. Watson, Power system Harmonics, Second Edition, John Wiley & Sons, Chichester, England (2004).
[7] Lyons R.G., Understanding Digital Signal Processing, Second Edition, Prentice Hall PTR (2004).
[8] Pang Hao, Li Dongxia, Zu Yunxiao et al., An improved algorithm for harmonic analysis of power system using FFT Technique, Proceedings of the CSEE, vol. 23, no. 6, pp. 50–54 (2003).
[9] Xu Y., Liu Y., Li Z., An accurate approach for harmonic detection based on 6-term cosine window and quadruple-spectrum-line interpolation FFT, Power System Protection and Control, vol. 44, no. 22, pp. 56–63 (2016), DOI: 10.7667/PSPC151933.
[10] Zhang C., Wang W., Qiu Y., Detection Method of Subsynchronous Harmonic in Regions with Large ScaleWind Power Paralleled in Grid, High Voltage Engineering, vol. 45, no. 7, pp. 2194–2202 (2019), DOI: 10.13336/j.1003-6520.hve.20181207008.
[11] Pham V.L., Wong K.P., Wavelet-transform-based algorithm for harmonic analysis of power system waveforms, IEE Proceedings on Generation, Transmission and Distribution, vol. 146, no. 3, pp. 249–254 (1999), DOI: 10.1049/ip-gtd:19990316.
[12] Liu Jun, Dai Benqi, Wang Zhiyue, Power harmonic analysis based on wavelet and FFT transform, J. Relay, vol. 35, no. 23, pp. 55–59 (2007).
[13] Cichocki A., Lobos T., Artificial neural networks for real-time estimation of basic waveforms of voltages and currents, IEEE Transactions on Power Systems, vol. 9, no. 2, pp. 612–618 (1994), DOI: 10.1109/59.317683.
[14] Xiang Dongyang, Wang Gongbao, Ma Weiming et al., A new method for non-integer harmonics measurement based on FFT algorithm and neutral network, Proceedings of the CSEE, vol. 25, no. 9, pp. 35–39 (2005), DOI: 10.3321/j.issn:0258-8013.2005.09.007.
[15] Jiao L., Du Y., An Approach for Electrical Harmonic Analysis Based on Interpolation DFT, Archives of Electrical Engineering, vol. 71, no. 2, pp. 445–454 (2022), DOI: 10.24425/aee.2022.140721.
[16] Nuttall A.H., Some Windows with Very Good Sidelobe Behavior, IEEE Transactions on Acoustics Speech and Signal Processing, vol. 29, no. 1, pp. 84–91 (1981), DOI: 10.1109/TASSP.1981.1163506.
Go to article

Authors and Affiliations

Ling Liu
1
ORCID: ORCID
Jinsong Zhang
1

  1. Shandong Polytechnic, China
Download PDF Download RIS Download Bibtex

Abstract

The half-metallic, mechanical, and transport properties of the quaternary Heusler compound of PdZrTiAl is discussed under hydrostatic pressures in the range of –11.4 GPa to 18.4 GPa in the framework of the density functional theory (DFT) and Boltzmann quasi-classical theory using the generalization gradient approximation (GGA). By applying the stress, the band gap in the minor spin increases so that the lowest band is obtained 0.25 eV at the pressure of –11.4 GPa while the maximum gap is calculated 0.9 eV at the pressure of 18.4 GPa. In all positive and negative pressures, the PdZrTiAl composition exhibits a half-metallic behavior 100% spin polarization at the Fermi level. It is also found that applying stress increases the Seebeck coefficient in both spin directions. In the minority spin, the n-type PdZrTiAl, the power factor (PF) for all the cases is greater in the equilibrium state than the strain and stress conditions whereas in the majority spin, the PF value of the stress state is greater than the other two. The non-dimensional figure of merit (ZT) is significant and is about one in spin down in the room temperature for the all pressure states that it remains on this value by applying pressure. The obtained elastic constants indicate that the PdZrTiAl crystalline structure has a mechanical stability. Based on the Yong (E), Bulk (B) and shear (G) modulus and Poisson (n) ratio, the brittle-ductile behavior of this compound has been investigated under pressure. The results indicate that PdZrTiAl has a ductile nature and it is a stiffness compound in which elastic and mechanical instability increases by applying strain.

Go to article

Authors and Affiliations

S. Parsamehr
A. Boochani
E. Sartipi
M. Amiri
S. Solaymani
S. Naderi
A. Aminian
Download PDF Download RIS Download Bibtex

Abstract

The electronic, magnetic, and optical properties of PtCoBi half-Heusler compound [001] surfaces and its bulk state have been investigated in the framework of density functional theory using GGA approximation. The half-metallic behaviors of CoBi-term, CoPt-term and PtBi-term decrease with respect to its bulk state. The spin polarization at the Fermi level is 73.2% for the bulk state, and it is –64.4% and –64.1% for the CoBi-term and PtBi-term, respectively while less polarization has been observed for the ­CoPt-term. All terminations have given almost similar optical responses to light. Plasmon oscillations for the terminations occur in the range of 12.5 to 14.5 eV (21 to 22 eV) along xx (zz), and it occurs at 23 eV for the bulk state. The refractive index for the bulk and all three terminations is very high in the infrared and visible areas, meaning a very strong metallic trend in these compounds. The phenomenon of super-luminance occurs for the incident light with energy exceeding 5.5 eV for all three terminations, and it occurs in the range of 10 eV for the bulk mode. These terminations show transparent behavior after the energy of 10 eV.
Go to article

Authors and Affiliations

Hamed Rezazadeh
1
ORCID: ORCID
Mohamadreza Hantehzadeh
1
ORCID: ORCID
Arash Boochani
2
ORCID: ORCID

  1. Islamic Azad University, Department of Physics, Science and Research Branch, Tehran, Iran
  2. Islamic Azad University, Department of Physics, Kermanshah Branch, Kermanshah, Iran
Download PDF Download RIS Download Bibtex

Abstract

Mechanical, electronic, thermodynamic phase diagram and optical properties of the FeVSb half-Heusler have been studied based on the density functional theory (DFT) framework. Studies have shown that this structure in the MgAgAs-type phase has static and dynamic mechanical stability with high thermodynamic phase consistency. Electronic calculations showed that this compound is a p-type semiconductor with an indirect energy gap of 0.39 eV. This compound’s optical response occurs in the infrared, visible regions, and at higher energies its dielectric sign is negative. The Plasmon oscillations have occurred in 20 eV, and its refraction index shifts to zero in 18 eV.
Go to article

Authors and Affiliations

A. Bagheri
1
A. Boochani
2
S.R. Masharian
1
F.H. Jafarpour
3

  1. Department of Physics, Hamedan Branch, Islamic Azad University, Hamedan, Iran
  2. Department of Physics, Kermanshah Branch, Islamic Azad University, Kermanshah, Iran
  3. Physics Department, Bu-Ali Sina University, 65174-4161 Hamedan, Iran
Download PDF Download RIS Download Bibtex

Abstract

A new solution to the problem of frequency estimation of a single sinusoid embedded in the white Gaussian noise is presented. It exploits, approximately, only one signal cycle, and is based on the well-known 2nd order autoregressive difference equation into which a downsampling is introduced. The proposed method is a generalization of the linear prediction based Prony method for the case of a single undamped sinusoid. It is shown that, thanks to the proposed downsampling in the linear prediction signal model, the overall variance of the least squares solution of frequency estimation is decreased, when compared to the Prony method, and locally it is even close to the Cramér–Rao Lower Bound, which is a significant improvement. The frequency estimation variance of the proposed solution is comparable with, computationally more complex, the Matrix Pencil and the Steiglitz–McBride methods. It is shown that application of the proposed downsampling to the popular smart DFT frequency estimation method also significantly reduces the method variance and makes it even better than the least squares smart DFT. The noise immunity of the proposed solution is achieved simultaneously with the reduction of computational complexity at the cost of narrowing the range of measured frequencies, i.e. a sinusoidal signal must be sufficiently oversampled to apply the proposed downsampling in the autoregressive model. The case of 64 samples per period with downsampling up to 16, i.e. 1/4th of the cycle, is presented in detail, but other sampling scenarios, from 16 to 512 samples per period, are considered as well.
Go to article

Bibliography

[1] Kay, S. M. (1993). Fundamentals of Statistical Signal Processing: Estimation Theory. Prentice-Hall
[2] Kay, S. M., & Marple, S. L. (1981). Spectrum analysis – A modern perspective. Proc. IEEE, 69, 1380–1419. https://doi.org/10.1109/PROC.1981.12184
[3] Kay, S. M. (1987). Modern Spectrum Analysis. Prentice-Hall.
[4] Zielinski, T. P., & Duda, K. (2011). Frequency and damping estimation methods - an overview. Metrology and Measurement Systems, 18(3), 505–528. https://doi.org/10.2478/v10178-011-0051-y
[5] Duda, K., & Zielinski, T. P. (2013). Efficacy of the frequency and damping estimation of a real-value sinusoid. IEEE Instrumentation & Measurement Magazine, 16(1), 48–58. https://doi.org/10.1109/ MIM.2013.6495682
[6] Borkowski, J., Kania, D., & Mroczka, J. (2018). Comparison of sine-wave frequency estimation methods in respect of speed and accuracy for a few observed cycles distorted by noise and harmonics. Metrology and Measurement Systems, 25(1), 283–302. https://doi.org/10.24425/119567
[7] Harris, F. J. (1978). On the use of windows for harmonic analysis with the discrete Fourier transform. Proceedings of the IEEE, 66(1), 51–83. https://doi.org/10.1109/PROC.1978.10837
[8] Zygarlicki, J., Zygarlicka, M., Mroczka, J., & Latawiec, K. J. (2010). A reduced Prony’s method in power-quality analysis – parameters selection. IEEE Transactions on Power Delivery, 25(1), 979–986. https://doi.org/10.1109/TPWRD.2009.2034745
[9] Zygarlicki, J., & Mroczka, J. (2014). Prony’s method with reduced sampling – numerical aspects. Metrology and Measurement Systems, 21(2), 521–534. https://doi.org/10.2478/mms-2014-0044
[10] Zygarlicki, J. (2017). Fast second order original Prony’s method for embedded measuring systems. Metrology and Measurement Systems, 24(3), 721–728. https://doi.org/10.1515/mms-2017-0058
[11] Hua, Y., & Sarkar, T. K., (1990). Matrix pencil method for estimating parameters of exponentially damped/undamped sinusoid in noise. IEEE Transactions on Acoustics, Speech, and Signal Processing, 38(4), 814–824. https://doi.org/10.1109/29.56027
[12] Steiglitz, K.,&McBride, L. (1965). A technique for identification of linear systems. IEEE Transactions on Automatic Control, 10(3), 461–464. https://doi.org/10.1109/TAC.1965.1098181
[13] McClellan, J. H., & Lee, D. (1991). Exact equivalence of the Steiglitz–McBride iteration and IQML. IEEE Transactions on Signal Processing, 39(1), 509–512. https://doi.org/10.1109/78.80841
[14] Wu, R. C., & Chiang, C. T. (2010). Analysis of the exponential signal by the interpolated DFT algorithm. IEEE Transactions on Instrumentation and Measurement, 59(12), 3306–3317. https://doi.org/10.1109/TIM.2010.2047301
[15] Derviškadic, A., Romano, & P., Paolone, M. (2018). Iterative-Interpolated DFT for Synchrophasor Estimation: A Single Algorithm for P- and M-Class Compliant PMUs. IEEE Transactions on Instrumentation and Measurement, 67(2), 547–558. https://doi.org/10.1109/TIM.2017.2779378
[16] Jacobsen, E., & Kootsookos, P. (2007). Fast, accurate frequency estimators. IEEE Signal Processing Magazine, 24(2), 123–125. https://doi.org/10.1109/MSP.2007.361611
[17] Duda, K., & Barczentewicz, S. (2014). Interpolated DFT for sin α (x) windows. IEEE Transactions on Instrumentation and Measurement, 63(3), 754–760. https://doi.org/10.1109/TIM.2013.2285795
[18] Yang, J. Z., & Liu, C. W. (2000). A precise calculation of power system frequency and phasor. IEEE Transactions on Power Delivery, 15(1), 494–499. https://doi.org/10.1109/61.852974
[19] Yang, J. Z., & Liu, C. W. (2001). A precise calculation of power system frequency. IEEE Transactions on Power Delivery, 16(2), 361–366. https://doi.org/10.1109/61.924811
[20] Xia, Y., He, Y., Wang, K., Pei, W., Blazic, Z., & Mandic, D. P. (2017). A complex least squares enhanced smart DFT technique for power system frequency estimation. IEEE Transactions on Power Delivery, 32(2), 1270–1278. https://doi.org/10.1109/TPWRD.2015.2418778
[21] Li, Z. (2021). A total least squares enhanced smart DFT technique for frequency estimation of unbalanced three-phase power systems. International Journal of Electrical Power & Energy Systems, 128, 106722. https://doi.org/10.1016/j.ijepes.2020.106722
[22] Xu, S., Liu, H., & Bi, T. (2020). A novel frequency estimation method based on complex Bandpass filters for P-class PMUs with short reporting latency. IEEE Transactions on Power Delivery. https://doi.org/10.1109/TPWRD.2020.3038703
[23] Duda, K., & Zielinski, T. P. (2021). P Class and M Class Compliant PMU Based on Discrete- Time Frequency-Gain Transducer. IEEE Transactions on Power Delivery. https://doi.org/10.1109/TPWRD.2021.3076831
[24] IEC, IEEE. (2018). Measuring relays and protection equipment – Part 118–1: Synchrophasor for power systems – Measurements (IEC/IEEE Standard No. 60255-118-1).
[25] Moon, T. K., & Stirling W. C. (1999). Mathematical Methods and Algorithms for Signal Processing. Prentice Hall.

Go to article

Authors and Affiliations

Krzysztof Duda
1
Tomasz P. Zieliński
2

  1. AGH University of Science and Technology, Faculty of Electrical Engineering, Automatics, Computer Science and Biomedical Engineering, Department of Measurement and Electronics, al. Mickiewicza 30, 30-059 Kraków, Poland
  2. AGH University of Science and Technology, Faculty of Computer Science, Electronics and Telecommunications, Institute of Telecommunications, al. Mickiewicza 30, 30-059 Kraków, Poland
Download PDF Download RIS Download Bibtex

Abstract

The effects of hydrogen absorption and manganese substitution on structural, electronic, optical, and thermoelectric properties of silicon-carbon nanotubes (SiCNT) are studied using the density functional theory and the GGA approximation. An examination of the PDOS curves and the electronic band structure showed that the Mn substitution leads to an increase in magnetic anisotropy and the occurrence of semi-metallic behavior and that the hydrogen absorption shifts the band gap toward the lower energies. A study of these nanostructures’ thermoelectric behavior reveals that the H absorption leads to a significant escalation in the figure of merit of the SiCNT to about 1.6 in the room temperature range. The effects of the H absorption on this nanotube’s optical properties, including the dielectric functions and its absorption spectra, are also investigated.
Go to article

Authors and Affiliations

Amir Toofani Shahraki
1
Heydar Ali Shafiei Gol
1
Salimeh Kimiagar
2
Naser Zare Dehnavi
1

  1. Department of Physics, Central Tehran Branch, Islamic Azad University, Tehran, Iran
  2. Nano Research Lab (NRL), Department of Physics, Central Tehran Branch, Islamic Azad University, Tehran, Iran
Download PDF Download RIS Download Bibtex

Abstract

Power systems that are highly loaded, especially by a stochastic supply of renewables and the presence of storages, require dynamic measurements for their optimal control. Phasor measurement units (PMUs) can be used to capture electrical parameters of a power system. Standards on the PMU dynamic performance have been modified to incorporate their new dynamic mode of operation. This paper examines the PMU dynamic performance and proposes essential algorithms for measurement accuracy verification. Measurements of dynamic input signals, which vary in amplitude or frequency, were taken during automated tests of two PMUs. The test results are presented and expounded with further recommendation for the performance requirements. This paper also presents and examines applied testing procedures with relevance to the specifications of the IEEE Standard for Synchrophasor C37.118.1™-2011 and its amendment C37.118.1a™-2014.

Go to article

Authors and Affiliations

Bartłomiej Arendarski
Steffen Rabe
Wolfram Heineken
Przemysław Komarnicki
Download PDF Download RIS Download Bibtex

Abstract

This paper presents the general solution of the least-squares approximation of the frequency characteristic of the data window by linear functions combined with zero padding technique. The approximation characteristic can be discontinuous or continuous, what depends on the value of one approximation parameter. The approximation solution has an analytical form and therefore the results have universal character. The paper presents derived formulas, analysis of approximation accuracy, the exemplary characteristics and conclusions, which confirm high accuracy of the approximation. The presented solution is applicable to estimating methods, like the LIDFT method, visualizations, etc.

Go to article

Authors and Affiliations

Józef Borkowski
Download PDF Download RIS Download Bibtex

Abstract

This overview paper presents and compares different methods traditionally used for estimating damped sinusoid parameters. Firstly, direct nonlinear least squares fitting the signal model in the time and frequency domains are described. Next, possible applications of the Hilbert transform for signal demodulation are presented. Then, a wide range of autoregressive modelling methods, valid for damped sinusoids, are discussed, in which frequency and damping are estimated from calculated signal linear self-prediction coefficients. These methods aim at solving, directly or using least squares, a matrix linear equation in which signal or its autocorrelation function samples are used. The Prony, Steiglitz-McBride, Kumaresan-Tufts, Total Least Squares, Matrix Pencil, Yule-Walker and Pisarenko methods are taken into account. Finally, the interpolated discrete Fourier transform is presented with examples of Bertocco, Yoshida, and Agrež algorithms. The Matlab codes of all the discussed methods are given. The second part of the paper presents simulation results, compared with the Cramér-Rao lower bound and commented. All tested methods are compared with respect to their accuracy (systematic errors), noise robustness, required signal length, and computational complexity.

Go to article

Authors and Affiliations

Tomasz Zieliński
Krzysztof Duda
Download PDF Download RIS Download Bibtex

Abstract

This paper derives analytical formulas for the systematic errors of the linear interpolated DFT (LIDFT) method when used to estimating multifrequency signal parameters and verifies this analysis using Monte-Carlo simulations. The analysis is performed on the version of the LIDFT method based on optimal approximation of the unit circle by a polygon using a pair of windows. The analytical formulas derived here take the systematic errors in the estimation of amplitude and frequency of component oscillations in the multifrequency signal as the sum of basic errors and the errors caused by each of the component oscillations. Additional formulas are also included to analyze particular quantities such as a signal consisting of two complex oscillations, and the analyses are verified using Monte-Carlo simulations.

Go to article

Authors and Affiliations

Józef Borkowski
Download PDF Download RIS Download Bibtex

Abstract

The paper deals with frequency estimation methods of sine-wave signals for a few signal cycles and consists of two parts. The first part contains a short overview where analytical error formulae for a signal distorted by noise and harmonics are presented. These formulae are compared with other accurate equations presented previously by the authors which are even more accurate below one cycle in the measurement window. The second part contains a comparison of eight estimation methods (ESPRIT, TLS, Prony LS, a newly developed IpDFT method and four other 3-point IpDFT methods) in respect of calculation time and accuracy for an ideal sine-wave signal, signal distorted by AWGN noise and a signal distorted by harmonics. The number of signal cycles is limited from 0.1 to 3 or 5. The results enable to select the most accurate/ fastest estimation method in various measurement conditions. Parametric methods are more accurate but also much slower than IpDFT methods (up to 3000 times for the number of samples equal to 5000). The presented method is more accurate than other IpDFT methods and much faster than parametric methods, which makes it possible to use it as an alternative, especially in real-time applications.
Go to article

Authors and Affiliations

Józef Borkowski
Dariusz Kania
Janusz Mroczka
Download PDF Download RIS Download Bibtex

Abstract

This paper deals with the amplitude estimation in the frequency domain of low-level sine waves, i.e. sine waves spanning a small number of quantization steps of an analog-to-digital converter. This is a quite common condition for high-speed low-resolution converters. A digitized sine wave is transformed into the frequency domain through the discrete Fourier transform. The error in the amplitude estimate is treated as a random variable since the offset and the phase of the sine wave are usually unknown. Therefore, the estimate is characterized by its standard deviation. The proposed model evaluates properly such a standard deviation by treating the quantization with a Fourier series approach. On the other hand, it is shown that the conventional noise model of quantization would lead to a large underestimation of the error standard deviation. The effects of measurement parameters, such as the number of samples and a kind of the time window, are also investigated. Finally, a threshold for the additive noise is provided as the boundary for validity of the two quantization models
Go to article

Authors and Affiliations

Diego Bellan
Download PDF Download RIS Download Bibtex

Abstract

In this study, the copper doping effect on the NiAl structural stability, strength, and electronic structure was investigated. The samples were prepared using induction melting at 2073 K. This material presents good mechanical and physical properties such as high-temperature strength, fatigue or impact, and corrosion resistance which meet technical requirements of many applications. The microstructure of the Cu-doped nickel aluminide was studied using a metallurgical microscope and its lattice parameter was also studied and characterized using an X-ray diffractometer for different concentrations of Cu. The lattice constant of the existing phases was calculated, and it was found that the lattice distortion and gamma prime phase energy have high values allowing the increase of the entropy term of the alloy and subsequently increasing its hardness. From the ab-initio calculation, it was determined that the Cu atoms have the Al sites as a preferred site and prefer to bond with Ni atoms which leads to the improvement of the material hardness. Ab-initio density functional theory was applied to study the formation energy that revealed increasing with Cu amount.
Go to article

Bibliography

  1. Bochenek, K. & Basista, M. Advances in processing of NiAl intermetallic alloys and composites for high temperature aerospace applications. Aerosp. Sci. 79, 136–146 (2015). https://doi.org/10.1016/j.paerosci.2015.09.003
  2. Chandler, K. A., Marine and Offshore Corrosion. (Elsevier, 1985). https://doi.org/10.1016/C2013-0-06267-6
  3. Busso, E. P. & McClintock, F. A. Mechanisms of cyclic defor-mation of NiAl single crystals at high temperatures. Acta Metall. Mater. 42, 3263–3275 (1994). https://doi.org/10.1016/0956-7151(94)90459-6
  4. Ren, W. L., Guo, J. T., Li, G. S. & Wu, J. S. The critical temperature for brittle-to-ductile transition of intermetallic compound based on NiAl. Lett. 58, 1272–1276 (2004). https://doi.org/10.1016/j.matlet.2003.09.020
  5. Porcayo-Calderon, J. et al. Effect of Cu addition on the electro-chemical corrosion performance of Ni3Al in 1.0 M H2SO4. Mater. Sci. Eng. 2015, 209286 (2015). https://doi.org/10.1155/2015/209286
  6. Huai, K., Guo, J., Gao, Q. & Yang, R. The microstructure of Au-doped NiAl–Cr(Mo) eutectic and its mechanical properties. Lett. 59, 3291–3294 (2005). https://doi.org/10.1016/j.matlet.2005.05.061
  7. Chiba, A., Hanada, S. & Watanabe, S. Improvement in ductility of Ni3Al by γ former doping. Sci. Eng. A 152, 108–113 (1992). https://doi.org/10.1016/0921-5093(92)90054-5
  8. Bhosale, A. G. & Chougule, B. K. Electrical conduction in Ni–Al ferrites. Lett. 60, 3912–3915 (2006). https://doi.org/10.1016/j.matlet.2006.03.139
  9. Darolia, R., Lahrman, D. & Field, R. The effect of iron, gallium and molybdenum on the room temperature tensile ductility of NiAl. Metall. Mater. 26, 1007–1012 (1992). https://doi.org/10.1016/0956-716X(92)90221-Y
  10. Pan, Y., Li, Y. & Zheng, Q. Influence of Ir concentration on the structure, elastic modulus and elastic anisotropy of NbIr based compounds from first-principles calculations. Alloys Compd. 789, 860–866 (2019). https://doi.org/10.1016/j.jallcom.2019.03.083
  11. Pan, Y., Wang, P. & Zhang, C.-M. Structure, mechanical, electronic and thermodynamic properties of Mo5Si3 from first-principles calculations. Int. 44, 12357–12362 (2018). https://doi.org/10.1016/j.ceramint.2018.04.023
  12. Pan, Y. First-principles investigation of the new phases and electro-chemical properties of MoSi2 as the electrode materials of lithium ion battery. Alloys Compd. 779, 813–820 (2019). https://doi.org/10.1016/j.jallcom.2018.11.352
  13. Pan, Y., Wang, S., Zhang, X. & Jia, L. First-principles investigation of new structure, mechanical and electronic properties of Mo-based silicides. Int. 44, 1744–1750 (2018). https://doi.org/10.1016/j.ceramint.2017.10.106
  14. Huang, J., Xing, H., Wen, Y. & Sun, J. Effect of Fe ternary addition on ductility of NiAl intermetallic alloy. Rare Met. 30, 316–319 (2011). https://doi.org/10.1007/s12598-011-0292-7
  15. Sugilal, G. et al. Indigenous development of induction skull melting technology for electromagnetic processing of refractory and reactive metals and alloys. Today Proc. 3, 2942–2950 (2016). https://doi.org/10.1016/j.matpr.2016.09.007
  16. Akai, H. Fast Korringa-Kohn-Rostoker coherent potential approx­imation and its application to FCC Ni-Fe systems. Phys. Condens. Matter 1, 8045–8064 (1989). https://doi.org/10.1088/0953-8984/1/43/006
  17. Nagy, Á. Density functional. Theory and application to atoms and molecules. Rep. 298, 1–79 (1998). https://doi.org/10.1016/S0370-1573(97)00083-5
  18. Zarhri, Z., Ziat, Y., El Rhazouani, O., Benyoussef, A. & Elkenz, A. Titanium atoms dimerization phenomenon and magnetic properties of titanium-antisite (TiO) and chromium doped rutile TiO2, ab-initio calculation. Phys. Chem. Solids 94, 12–16 (2016). https://doi.org/10.1016/j.jpcs.2016.03.002
  19. Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple. Rev. Lett. 77, 3865–3868 (1996). https://doi.org/10.1103/PhysRevLett.77.3865
  20. Zarhri, Z. et al. Ab-initio study of magnetism behavior in TiO2 semiconductor with structural defects. Magn. Magn. Mater. 406, 212–216 (2016). https://doi.org/10.1016/j.jmmm.2016.01.029
  21. Pan, Y. & Wen, M. Noble metals enhanced catalytic activity of anatase TiO2 for hydrogen evolution reaction. J. Hydrogen Energy 43, 22055–22063 (2018). https://doi.org/10.1016/j.ijhydene.2018.10.093
  22. Pan, Y., Li, Y. Q., Zheng, Q. H. & Xu, Y. Point defect of titanium sesquioxide Ti2O3 as the application of next generation Li-ion batteries. Alloys Compd. 786, 621–626 (2019). https://doi.org/10.1016/j.jallcom.2019.02.054
  23. Pan, Y. Theoretical discovery of high capacity hydrogen storage metal tetrahydrides. J. Hydrogen Energy 44, 18153–18158 (2019). https://doi.org/10.1016/j.jallcom.2019.02.054
  24. Pan, Y. Vacancy-enhanced cycle life and electrochemical perfor-mance of lithium-rich layered oxide Li2RuO3. Int. 45, 18315–18319 (2019). https://doi.org/10.1016/j.ceramint.2019.06.044
  25. Ziat, Y., Hammi, M., Zarhri, Z., Laghlimi, C. & El Rhazouani, O. Ferrimagnetism and ferromagnetism behavior in (C, Mn) co-doped SnO2 for microwave and spintronic: Ab initio investigation. Magn. Magn. Mater. 483, 219–223 (2019). https://doi.org/10.1016/j.jmmm.2019.03.084
  26. Liu, J., Cao, J., Lin, X., Song, X. & Feng, J. Microstructure and mechanical properties of diffusion bonded single crystal to polycrystalline Ni-based superalloys joint. Des. 49, 622–626 (2013). https://doi.org/10.1016/j.matdes.2013.02.022
  27. Zheng, L., Sheng, L. Y., Qiao, Y. X., Yang, Y. & Lai, C. Influence of Ho and Hf on the microstructure and mechanical properties of NiAl and NiAl-Cr(Mo) eutectic alloy. Res. Express 6, 046502 (2019). https://doi.org/10.1088/2053-1591/aaf8ea
  28. Sheng, L. Y. et al. Microstructure characteristics and compressive properties of NiAl-based multiphase alloy during heat treatments. Sci. Eng. A 528, 8324–8331 (2011). https://doi.org/10.1088/2053-1591/aaf8ea
  29. Sheng, L. et al. Effect of Au addition on the microstructure and mechanical properties of NiAl intermetallic compound. Intermetallics 18, 740–744 (2010). https://doi.org/10.1016/j.intermet.2009.10.015
  30. Wittmann, F. H. Crack formation and fracture energy of normal and high strength concrete. Sadhana 27, 413–423 (2002). https://doi.org/10.1007/BF02706991
  31. Ziat, Y. et al. First-principles study of magnetic and electronic properties of fluorine-doped Sn98Mn0.02O2 system. J. Supercond. Novel Magn. 29, 2979–2985 (2016). https://doi.org/10.1007/s10948-016-3609-9
  32. Han, Y.-J. & Park, S.-J. Influence of nickel nanoparticles on hydro-gen storage behaviors of MWCNTs. Surf. Sci. 415, 85–89 (2017). https://doi.org/10.1016/j.apsusc.2016.12.108
  33. Tsao, T.-K. & Yeh, A.-C. The thermal stability and strength of highly alloyed Ni3 Mater. Trans. 56, 1905–1910 (2015). https://doi.org/10.2320/matertrans.M2015298
Go to article

Authors and Affiliations

Zakaryaa Zarhri
1
ORCID: ORCID

  1. CONACYT-Tecnológico Nacional de México/I.T. Chetumal; Insurgentes 330, C.P. 77013, Chetumal, Quintana Roo, Mexico
Download PDF Download RIS Download Bibtex

Abstract

In this article, synthesis, electronic and optical properties of an N-cyclohexyl-acrylamide (NCA) molecule are described based on different solvent environments and supported by theoretical calculations. Theoretical calculations have been carried out using a density function theory (DFT). Temperature dependence of the sample electrical resistance has been obtained by a four-point probe technique. Experimental and semi-theoretical parameters such as optical density, transmittance, optical band gap, refractive index of the NCA for different solvents were obtained. Both optical values and electrical resistance values have shown that NCA is a semiconductor material. The values of HOMO and LUMO energy levels of the headline molecule indicate that it can be used as the electron transfer material in OLEDs. All results obtained confirm that the NCA is a candidate molecule for OLED and optoelectronic applications.

Go to article

Authors and Affiliations

E. Tanış
N. Çankaya
Download PDF Download RIS Download Bibtex

Abstract

Tris(8-hydroxyquinoline)aluminium with poly(N-vinylcarbazole) (Alq 3:PVK) or polystyrene sulfonate (Alq 3:PSS) were deposited by spin-coating on glass and silicon substrates. SEM measurements show that relatively smooth thin films were obtained. Fourier transform infrared measurements were performed to confirm the composition of the samples. The optical properties of thin films containing Alq 3:PVK and Alq 3:PSS were characterised using absorption spectroscopy and spectroscopic ellipsometry. It was found that the absorption spectrum of Alq 3:PVK is characterised by four bands, while for Alq 3:PSS only three bands are visible. The photoluminescence of the studied thin layers shows a peak with a maximum at about 500 nm. Additionally, cyclic voltammetry of Alq 3 is also presented. Theoretical density functional theory calculations provide the insight into the interaction and nature of Alq 3:PVK and Alq 3:PSS excited states. Finally, the organic light-emitting diode (OLED) structure based on Alq 3:PVK was fabricated and showed strong electro-luminescence with a green emission at 520 nm. The results of the device show that the ITO/PEDOT:PSS/Alq 3:PVK/Ca/Al system can be useful for the production of low-cost OLEDs with Alq 3:PVK as an active layer for future lighting applications.
Go to article

Authors and Affiliations

Małgorzata Sypniewska
1
ORCID: ORCID
Monika Pokladko-Kowar
2
ORCID: ORCID
Anna Kaczmarek-Kedziera
3
ORCID: ORCID
Iulia E. Brumboiu
1
ORCID: ORCID
Viviana Figà
4
ORCID: ORCID
Aleksandra Apostoluk
5
ORCID: ORCID
Peng Song
6 7
Junyan Liu
6 8
ORCID: ORCID
Robert Szczesny
9
ORCID: ORCID
Ewa Gondek
2
ORCID: ORCID
Beata Derkowska-Zielinska
1
ORCID: ORCID

  1. Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziądzka 5, Torun 87-100, Poland
  2. Department of Physics, Cracow University of Technology, Podchorążych 1, 30-084 Krakow, Poland
  3.  Faculty of Chemistry, Nicolaus Copernicus University in Torun, Gagarina 7, Torun 87-100, Poland
  4. Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche, Università di Palermo, Viale delle Scienze, Parco d’Orleans II, 90128 Palermo, Italy
  5. Université de Lyon, INSA Lyon, ECL, CNRS, UCBL, CPE Lyon, INL, UMR5270, 69621 Villeurbanne, France
  6. State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin, 150001, China
  7. School of Instrumentation Science and Engineering, Harbin Institute of Technology, Harbin, 150001, China
  8. School of Mechatronics Engineering, Harbin Institute of Technology, Harbin, 150001, China
  9. Faculty of Chemistry, Nicolaus Copernicus University in Torun, Gagarina 7, Torun 87-100, Poland
Download PDF Download RIS Download Bibtex

Abstract

The electronic, optical and thermoelectric properties of zirconia-based MgZrO3 oxide have been studied theoretically at a variant pressure up to 25 GPa. Calculations for the formation energy and tolerance factor reveal the thermodynamic and structural stability of MgZrO3. To tune the indirect band gap from to a direct band gap, the optimized structure of MgZrO3 has been subjected to external pressure up to 25 GPa. The optical properties have been discussed in the form of dielectric constant and refraction that brief us about the dispersion, polarization, absorption, and transparency of the MgZrO3. In the end, the thermoelectric parameters have been analyzed at variant pressure against the chemical potential and temperature. The narrow band gap and high absorption in the ultraviolet region increase the demand of the studied oxide for energy harvesting device applications.

Go to article

Authors and Affiliations

N.A. Noor
M. Rashid
Q. Mahmood
B. Ul Haq
M.A. Naeem
A. Laref
Download PDF Download RIS Download Bibtex

Abstract

The electronic, optical and thermoelectric properties of MoS2 nano-sheet in presence of the Ru impurity have been calculated by density functional theory framework with Generalized Gradient approximation. The MoRuS2 nano-sheet electronic structure was changed to the n-type semiconductor by 1.3 eV energy gap. The optical coefficients were shown that the loosing optical energy occurred in the higher ultraviolet region, so this compound is a promising candidate for optical sensing in the infrared and visible range. The thermoelectric behaviors were implied to the good merit parameter in the 100K range and room temperatures and also has high amount of power factor in 600K which made it for power generators applications.
Go to article

Authors and Affiliations

Firouzeh Motamad Dezfuli
1
ORCID: ORCID
Arash Boochani
2
ORCID: ORCID
Sara Sadat Parhizgar
1
ORCID: ORCID
Elham Darabi
1
ORCID: ORCID

  1. Department of Physics, Faculty of Sciences, Science and Research Branch, Islamic Azad University, Tehran, Iran
  2. Department of Physics, Kermanshah Branch, Islamic Azad University, Kermanshah, Iran
Download PDF Download RIS Download Bibtex

Abstract

Quality of energy produced in renewable energy systems has to be at the high level specified by respective standards and directives. One of the most important factors affecting quality is the estimation accuracy of grid signal parameters. This paper presents a method of a very fast and accurate amplitude and phase grid signal estimation using the Fast Fourier Transform procedure and maximum decay side-lobes windows. The most important features of the method are elimination of the impact associated with the conjugate’s component on the results and its straightforward implementation. Moreover, the measurement time is very short ‒ even far less than one period of the grid signal. The influence of harmonics on the results is reduced by using a bandpass pre-filter. Even using a 40 dB FIR pre-filter for the grid signal with THD ≈ 38%, SNR ≈ 53 dB and a 20‒30% slow decay exponential drift the maximum estimation errors in a real-time DSP system for 512 samples are approximately 1% for the amplitude and approximately 8.5・10‒2 rad for the phase, respectively. The errors are smaller by several orders of magnitude with using more accurate pre-filters.

Go to article

Authors and Affiliations

Józef Borkowski
Dariusz Kania
Download PDF Download RIS Download Bibtex

Abstract

This study is based on the investigation of AlSb layer thickness effect on heavy−hole light−hole (HH−LH) splitting and band gap energies in a recently developed N−structure based on InAs/AlSb/GaSb type II superlattice (T2SL) p−i−n photodetector.eFirst principle calculations were carried out tailoring the band gap and HH−LH splitting energies for two possible interface transition alloys of InSb and AlAs between InAs and AlSb interfaces in the superlattice. Results show that AlSb and InAs−GaSb layer thicknesses enable to control HH−LH splitting energies to desired values for Auger recombination process where AlSb/GaSb total layer thickness is equal to InAs layers for the structures with InSb and AlAs interfaces

Go to article

Authors and Affiliations

M.M. Alyoruk
Y. Ergun
M. Hostut

This page uses 'cookies'. Learn more