IPAC2021 - List of Authors (Ries, M.)

Paper	Title	Page
MOXB01	Progress Towards Realisation of Steady-State Microbunching at the Metrology Light Source
	J. Feikes, A. Kruschinski, J. Li, A.N. Matveenko, Y. Petenev, M. Ries HZB, Berlin, Germany A. Chao SLAC, Menlo Park, California, USA X.J. Deng, W.-H. Huang, C.-X. Tang, L.X. Yan TUB, Beijing, People’s Republic of China A. Hoehl, R. Klein PTB, Berlin, Germany
	Coherent radiation is a powerful scheme for storage-ring-based synchrotron radiation sources as its intensity increases with the square of the number of radiating electrons. Formation of bunches or sub-bunches shorter than the radiation wavelength, i.e., microbunching, is necessary for the radiation from different electrons to add in phase and therefore cohere. Recently at the MLS it has been shown that in dedicated isochronous optics an electron beam energy modulation induced by an externally applied 1064-nm-wavelength laser in an undulator leads to the formation of sub-um microbunches one turn later, providing the basis for the implementation of steady-state microbunching in electron storage rings to generate high-repetition, high-power coherent radiation. Here we report on the recent progress and continuing development of this experiment. Deng, X., Chao, A., Feikes, J. et al. Experimental demonstration of the mechanism of steady-state microbunching. Nature 590, 576-579 (2021). https://doi.org/10.1038/s41586-021-03203-0*
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MOPAB126	BESSY III & MLS II - Status of the Development of the New Photon Science Facility in Berlin	451
	P. Goslawski, M. Abo-Bakr, F. Andreas, M. Arlandoo, J. Bengtsson, V. Dürr, K. Holldack, J.-G. Hwang, A. Jankowiak, B.C. Kuske, J. Li, A.N. Matveenko, T. Mertens, A. Meseck, E.C.M. Rial, M. Ries, M.K. Sauerborn, A. Schälicke, M. Scheer, P. Schnizer, L. Shi, J. Viefhaus HZB, Berlin, Germany J. Lüning UPMC, Paris, France
	HZB operates and develops two synchrotron radiation sources at Berlin Adlershof. The larger one, BESSY II with an energy of 1.7 GeV and 240 m circumference is optimized for soft-X rays and in operation since 1999. The smaller one is the MLS (Metrology Light Source), owned by the Physikalische Technische Bundesanstalt (PTB) - Germany’s National Metrology Institute. It is designed to fulfill the special metrology needs of the PTB with an energy of 0.6 GeV and 48 m circumference, covering the spectral range from THz and IR to EUV/VUV. In 2020 a discussion process has been started to define the requirements for successors of BESSY II and MLS and to study the possibilities integrate them into a new photon science facility in Berlin Adlershof. Here, we give a status report and present a first envisaged parameter space to both machines (see also MOPAB262, MOPAB220, MOPAB048, MOPAB242).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB126
About •	paper received ※ 18 May 2021 paper accepted ※ 24 June 2021 issue date ※ 18 August 2021
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MOPAB296	Statistical Analysis of 2D Single-Shot PPRE Bunch Measurements	939
	M. Koopmans, J.-G. Hwang, A. Jankowiak, M. Ries, A. Schälicke, G. Schiwietz HZB, Berlin, Germany
	The pulse picking by resonant excitation (PPRE) method* is used to realize pseudo single-bunch radiation from a complex filling pattern at the BESSY II storage ring. The PPRE bunch is excited in the horizontal plane by a quasi-resonant incoherent perturbation to increase the emittance of this bunch. Therefore, the synchrotron light of the PPRE bunch can be separated by collimation from the radiation of the main bunch train at dedicated beamlines for timing users. The properties of the PPRE bunch depend on the storage ring settings and on the excitation parameters. It is not trivial to distinguish between the wanted intrinsic bunch broadening and an additional position fluctuation of the PPRE bunch. Using the potential of the new diagnostics beamline with the possibility to observe an additional spatial dimension with a fast streak camera, we introduce a new method to study the properties of the PPRE bunch. Applying a statistical analysis to a series of single-turn images enables distinguishing between horizontal orbit motion and the broadening of the bunch due to the excitation. Measurements are presented and the results are compared with data from the BPM system. K. Holldack et al., Nature Commun. 5 (2014) 4010. J.-G. Hwang et al., Nucl. Instrum. Methods A940 (2019) 387. * G. Schiwietz et al., Nucl. Instrum. Methods A990 (2021) 164992.
	Poster MOPAB296 [2.074 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB296
About •	paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 23 August 2021
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TUPAB213	Important Drift Space Contributions to Non-Linear Beam Dynamics	1914
	J. Frank, M. Arlandoo, P. Goslawski, J. Li, T. Mertens, M. Ries HZB, Berlin, Germany
	This paper presents an in-depth analysis of the non-linear contributions of drift spaces in beam dynamics for the creation of Transverse Resonance Island Buckets (TRIBs). TRIBs have been successfully generated in BESSY II and MLS at the Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB). They offer the possibility of generating a second stable orbit and, by populating the orbit with a different electron bunch pattern, allow to effectively have two distinct radiation sources in the same machine individually tailored to different user needs. We demonstrate the generation of TRIBs by order of non-linearity on simple lattice configurations by only treating the drift space as the non-linear element. Moreover, we also insert other non-linear magnets to show how they modify the already generated TRIBs from the drift spaces. We conclude by giving a qualitative analysis of the occurring effects, which provides a guideline as to when the linear approximation is insufficient and the non-linear contribution has to be taken into account.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB213
About •	paper received ※ 12 May 2021 paper accepted ※ 31 August 2021 issue date ※ 29 August 2021
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TUPAB214	Alpha Buckets in Longitudinal Phase Space: A Bifurcation Analysis	1917
	J. Frank, M. Arlandoo, P. Goslawski, T. Mertens, M. Ries HZB, Berlin, Germany
	At HZB’s BESSY II and MLS facilities we have the ability to tune the momentum compaction factor α up to second non-linear order. The non-linear dependence α(δ) brings qualitative changes to the longitudinal phase space and introduces new fix points α(δ)=0 which produce the so-called α-buckets. We present with this paper an analysis of this phenomena from the standpoint of bifurcation theory. With this approach we were able to characterize the nature of the fix points and their position in direct dependence on the tunable parameters. Furthermore, we are able to place stringent conditions onto the tunable parameters to either create or destroy α-buckets.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB214
About •	paper received ※ 12 May 2021 paper accepted ※ 17 June 2021 issue date ※ 26 August 2021
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TUPAB215	Novel Non-Linear Particle Tracking Approach Employing Lie Algebraic Theory in the TensorFlow Environment	1920
	J. Frank, M. Arlandoo, P. Goslawski, J. Li, T. Mertens, M. Ries, L. Vera Ramirez HZB, Berlin, Germany
	With this paper we present first results for encoding Lie transformations as computational graphs in Tensorflow that are used as layers in a neural network. By implementing a recursive differentiation scheme and employing Lie algebraic arguments we were able to reproduce the diagrams for well known lattice configurations. We track through simple optical lattices that are encountered as the main constituents of accelerators and demonstrate the flexibility and modularity our approach offers. The neural network can represent the optical lattice with predefined coefficients allowing for particle tracking for beam dynamics or can learn from experimental data to fine-tune beam optics.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB215
About •	paper received ※ 12 May 2021 paper accepted ※ 31 August 2021 issue date ※ 21 August 2021
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TUPAB217	Effect of Undulators on Transverse Resonant Island Orbits	1927
	E.C.M. Rial, J. Bahrdt, P. Goslawski, A. Meseck, M. Ries, M. Scheer HZB, Berlin, Germany
	For one week in October 2020, BESSY II offered a Two Orbit mode to users for the first time. In this Two Orbit mode, the existence of transverse resonant island buckets* are exploited to store a second beam in the storage ring as an ’island orbit’, away from the primary beam axis. This mode was offered with free range of motion of the 12 out of vacuum undulators installed at the BESSY II ring. Diagnostics of the island orbit were limited to a single camera monitoring bending magnet radiation from a single dipole. A significant motion of the island orbit was observed on this diagnostic and correlated with undulator motion. This observation is reported, and simulations presented to demonstrate how this motion could arise. Correction schemes are suggested and discussed. Two Orbit - a report on the first scheduled week of TRIBs user operation at BESSY II, M. Ries et al, these proceedings *Proc. IPAC 2016, Busan, S Korea, paper THPMR017, p. 3427
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB217
About •	paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 22 August 2021
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WEPAB134	Experimental Studies of the In-Vacuum-Cryogenic Undulator Effect on Beam Instabilities at BESSY II	2929
	M. Huck, J. Bahrdt, A. Meseck, G. Rehm, M. Ries, A. Schälicke HZB, Berlin, Germany
	A new in-vacuum cryogenic permanent magnet undulator (CPMU17) has been installed in summer 2018 in the BESSY II storage ring at HZB. Such a small gap in-vacuum undulator device increases the impedance of the storage ring and can contribute to the instabilities that adversely affect the beam quality and the device itself. To identify and explore the effects of CPMU17 on the instabilities at BESSY II, grow-damp and drive-damp experiments have been conducted using the installed bunch-by-bunch feedback system. In this paper, the first results of the mode and gap analysis of these studies with a brief overview of other impedance studies will be presented.
	Poster WEPAB134 [1.079 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB134
About •	paper received ※ 17 May 2021 paper accepted ※ 02 July 2021 issue date ※ 23 August 2021
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WEPAB317	Online Model Developments for BESSY II and MLS	3413
	P. Schnizer, J. Bengtsson, T. Birke, J. Li, T. Mertens, M. Ries, A. Schälicke, L. Vera Ramirez HZB, Berlin, Germany
	Digital models have been developed over a long time for preparing accelerator commissioning next to benchmarking theory predictions to machine measurements. These digital models are nowadays being realized as digital shadows or digital twins. Accelerator commissioning requires periodic setup and review of the machine status. Furthermore, different measurements are only practical by comparison to the machine model (e.g. beam based alignment). In this paper we describe the architecture chosen for our models, describe the framework Bluesky for measurement orchestration and report on our experience exemplifying on dynamic aperture scans. Furthermore we describe our plans to extend the models applied to BESSY~II and MLS to the currently planned machines BESSY~III and MLS~II.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB317
About •	paper received ※ 19 May 2021 paper accepted ※ 28 July 2021 issue date ※ 21 August 2021
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Paper

Title

Page

MOXB01

Progress Towards Realisation of Steady-State Microbunching at the Metrology Light Source

J. Feikes, A. Kruschinski, J. Li, A.N. Matveenko, Y. Petenev, M. Ries
HZB, Berlin, Germany
A. Chao
SLAC, Menlo Park, California, USA
X.J. Deng, W.-H. Huang, C.-X. Tang, L.X. Yan
TUB, Beijing, People’s Republic of China
A. Hoehl, R. Klein
PTB, Berlin, Germany

Coherent radiation is a powerful scheme for storage-ring-based synchrotron radiation sources as its intensity increases with the square of the number of radiating electrons. Formation of bunches or sub-bunches shorter than the radiation wavelength, i.e., microbunching, is necessary for the radiation from different electrons to add in phase and therefore cohere. Recently at the MLS it has been shown that in dedicated isochronous optics an electron beam energy modulation induced by an externally applied 1064-nm-wavelength laser in an undulator leads to the formation of sub-um microbunches one turn later*, providing the basis for the implementation of steady-state microbunching in electron storage rings to generate high-repetition, high-power coherent radiation. Here we report on the recent progress and continuing development of this experiment.
Deng, X., Chao, A., Feikes, J. et al. Experimental demonstration of the mechanism of steady-state microbunching. Nature 590, 576-579 (2021). https://doi.org/10.1038/s41586-021-03203-0

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MOPAB126

BESSY III & MLS II - Status of the Development of the New Photon Science Facility in Berlin

451

P. Goslawski, M. Abo-Bakr, F. Andreas, M. Arlandoo, J. Bengtsson, V. Dürr, K. Holldack, J.-G. Hwang, A. Jankowiak, B.C. Kuske, J. Li, A.N. Matveenko, T. Mertens, A. Meseck, E.C.M. Rial, M. Ries, M.K. Sauerborn, A. Schälicke, M. Scheer, P. Schnizer, L. Shi, J. Viefhaus
HZB, Berlin, Germany
J. Lüning
UPMC, Paris, France

HZB operates and develops two synchrotron radiation sources at Berlin Adlershof. The larger one, BESSY II with an energy of 1.7 GeV and 240 m circumference is optimized for soft-X rays and in operation since 1999. The smaller one is the MLS (Metrology Light Source), owned by the Physikalische Technische Bundesanstalt (PTB) - Germany’s National Metrology Institute. It is designed to fulfill the special metrology needs of the PTB with an energy of 0.6 GeV and 48 m circumference, covering the spectral range from THz and IR to EUV/VUV. In 2020 a discussion process has been started to define the requirements for successors of BESSY II and MLS and to study the possibilities integrate them into a new photon science facility in Berlin Adlershof. Here, we give a status report and present a first envisaged parameter space to both machines (see also MOPAB262, MOPAB220, MOPAB048, MOPAB242).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB126

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paper received ※ 18 May 2021 paper accepted ※ 24 June 2021 issue date ※ 18 August 2021

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MOPAB296

Statistical Analysis of 2D Single-Shot PPRE Bunch Measurements

939

M. Koopmans, J.-G. Hwang, A. Jankowiak, M. Ries, A. Schälicke, G. Schiwietz
HZB, Berlin, Germany

The pulse picking by resonant excitation (PPRE) method* is used to realize pseudo single-bunch radiation from a complex filling pattern at the BESSY II storage ring. The PPRE bunch is excited in the horizontal plane by a quasi-resonant incoherent perturbation to increase the emittance of this bunch**. Therefore, the synchrotron light of the PPRE bunch can be separated by collimation from the radiation of the main bunch train at dedicated beamlines for timing users. The properties of the PPRE bunch depend on the storage ring settings and on the excitation parameters. It is not trivial to distinguish between the wanted intrinsic bunch broadening and an additional position fluctuation of the PPRE bunch. Using the potential of the new diagnostics beamline with the possibility to observe an additional spatial dimension with a fast streak camera, we introduce a new method to study the properties of the PPRE bunch***. Applying a statistical analysis to a series of single-turn images enables distinguishing between horizontal orbit motion and the broadening of the bunch due to the excitation. Measurements are presented and the results are compared with data from the BPM system.
* K. Holldack et al., Nature Commun. 5 (2014) 4010.
** J.-G. Hwang et al., Nucl. Instrum. Methods A940 (2019) 387.
*** G. Schiwietz et al., Nucl. Instrum. Methods A990 (2021) 164992.

Poster MOPAB296 [2.074 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB296

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paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 23 August 2021

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TUPAB213

Important Drift Space Contributions to Non-Linear Beam Dynamics

1914

J. Frank, M. Arlandoo, P. Goslawski, J. Li, T. Mertens, M. Ries
HZB, Berlin, Germany

This paper presents an in-depth analysis of the non-linear contributions of drift spaces in beam dynamics for the creation of Transverse Resonance Island Buckets (TRIBs). TRIBs have been successfully generated in BESSY II and MLS at the Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB). They offer the possibility of generating a second stable orbit and, by populating the orbit with a different electron bunch pattern, allow to effectively have two distinct radiation sources in the same machine individually tailored to different user needs. We demonstrate the generation of TRIBs by order of non-linearity on simple lattice configurations by only treating the drift space as the non-linear element. Moreover, we also insert other non-linear magnets to show how they modify the already generated TRIBs from the drift spaces. We conclude by giving a qualitative analysis of the occurring effects, which provides a guideline as to when the linear approximation is insufficient and the non-linear contribution has to be taken into account.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB213

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paper received ※ 12 May 2021 paper accepted ※ 31 August 2021 issue date ※ 29 August 2021

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TUPAB214

Alpha Buckets in Longitudinal Phase Space: A Bifurcation Analysis

1917

J. Frank, M. Arlandoo, P. Goslawski, T. Mertens, M. Ries
HZB, Berlin, Germany

At HZB’s BESSY II and MLS facilities we have the ability to tune the momentum compaction factor α up to second non-linear order. The non-linear dependence α(δ) brings qualitative changes to the longitudinal phase space and introduces new fix points α(δ)=0 which produce the so-called α-buckets. We present with this paper an analysis of this phenomena from the standpoint of bifurcation theory. With this approach we were able to characterize the nature of the fix points and their position in direct dependence on the tunable parameters. Furthermore, we are able to place stringent conditions onto the tunable parameters to either create or destroy α-buckets.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB214

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paper received ※ 12 May 2021 paper accepted ※ 17 June 2021 issue date ※ 26 August 2021

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TUPAB215

Novel Non-Linear Particle Tracking Approach Employing Lie Algebraic Theory in the TensorFlow Environment

1920

J. Frank, M. Arlandoo, P. Goslawski, J. Li, T. Mertens, M. Ries, L. Vera Ramirez
HZB, Berlin, Germany

With this paper we present first results for encoding Lie transformations as computational graphs in Tensorflow that are used as layers in a neural network. By implementing a recursive differentiation scheme and employing Lie algebraic arguments we were able to reproduce the diagrams for well known lattice configurations. We track through simple optical lattices that are encountered as the main constituents of accelerators and demonstrate the flexibility and modularity our approach offers. The neural network can represent the optical lattice with predefined coefficients allowing for particle tracking for beam dynamics or can learn from experimental data to fine-tune beam optics.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB215

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paper received ※ 12 May 2021 paper accepted ※ 31 August 2021 issue date ※ 21 August 2021

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TUPAB217

Effect of Undulators on Transverse Resonant Island Orbits

1927

E.C.M. Rial, J. Bahrdt, P. Goslawski, A. Meseck, M. Ries, M. Scheer
HZB, Berlin, Germany

For one week in October 2020, BESSY II offered a Two Orbit mode to users for the first time*. In this Two Orbit mode, the existence of transverse resonant island buckets** are exploited to store a second beam in the storage ring as an ’island orbit’, away from the primary beam axis. This mode was offered with free range of motion of the 12 out of vacuum undulators installed at the BESSY II ring. Diagnostics of the island orbit were limited to a single camera monitoring bending magnet radiation from a single dipole. A significant motion of the island orbit was observed on this diagnostic and correlated with undulator motion. This observation is reported, and simulations presented to demonstrate how this motion could arise. Correction schemes are suggested and discussed.
*Two Orbit - a report on the first scheduled week of TRIBs user operation at BESSY II, M. Ries et al, these proceedings
**Proc. IPAC 2016, Busan, S Korea, paper THPMR017, p. 3427

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB217

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paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 22 August 2021

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WEPAB134

Experimental Studies of the In-Vacuum-Cryogenic Undulator Effect on Beam Instabilities at BESSY II

2929

M. Huck, J. Bahrdt, A. Meseck, G. Rehm, M. Ries, A. Schälicke
HZB, Berlin, Germany

A new in-vacuum cryogenic permanent magnet undulator (CPMU17) has been installed in summer 2018 in the BESSY II storage ring at HZB. Such a small gap in-vacuum undulator device increases the impedance of the storage ring and can contribute to the instabilities that adversely affect the beam quality and the device itself. To identify and explore the effects of CPMU17 on the instabilities at BESSY II, grow-damp and drive-damp experiments have been conducted using the installed bunch-by-bunch feedback system. In this paper, the first results of the mode and gap analysis of these studies with a brief overview of other impedance studies will be presented.

Poster WEPAB134 [1.079 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB134

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paper received ※ 17 May 2021 paper accepted ※ 02 July 2021 issue date ※ 23 August 2021

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WEPAB317

Online Model Developments for BESSY II and MLS

3413

P. Schnizer, J. Bengtsson, T. Birke, J. Li, T. Mertens, M. Ries, A. Schälicke, L. Vera Ramirez
HZB, Berlin, Germany

Digital models have been developed over a long time for preparing accelerator commissioning next to benchmarking theory predictions to machine measurements. These digital models are nowadays being realized as digital shadows or digital twins. Accelerator commissioning requires periodic setup and review of the machine status. Furthermore, different measurements are only practical by comparison to the machine model (e.g. beam based alignment). In this paper we describe the architecture chosen for our models, describe the framework Bluesky for measurement orchestration and report on our experience exemplifying on dynamic aperture scans. Furthermore we describe our plans to extend the models applied to BESSY~II and MLS to the currently planned machines BESSY~III and MLS~II.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB317

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paper received ※ 19 May 2021 paper accepted ※ 28 July 2021 issue date ※ 21 August 2021

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