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Vol.28, June 2021

The University of Electro-Communications 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585© 2021 The University of Electro-Communications.

Vol.28, June 2021

Research Highlights
 Efficient & reliable data processing for scalable Internet of Things: Innovative amplify-andforward-based AirComp
 Innovative building blocks for the quantum internet: All fiber platform for quantum photonic
processing on tapered optical fibers
 Bacteria in the spotlight: Bacterial community exhibits only counterclockwise movement

Researcher Video Profiles
 How and why do bacteria move?

Topics Insights into modern reliability engineering

News and Events
 Joint demonstration experiment on visualizing carbon dioxide concentration inside Chofu City
Hall with eight IoT sensors

The University of Electro-Communications 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585© 2021 The University of Electro-Communications.

Vol.28, June 2021

Efficient & reliable data processing for scalable Internet of Things: Innovative amplify-andforward-based AirComp

One of the critical issues for the proliferation of Internet of Things (IoT) is the collection andcomputational analysis of wireless data from huge networks of smart sensors being implemented inapplications that include smart transportation and cities. Recently, the technique of over-the-air
computation (AirComp) has been proposed as an integrated approach for collection and processingof data from sensor networks transmitting Big-data simultaneously. Notably, although this method isefficient, it requires that all signals from nodes arrive simultaneously at the sink, aligned in signal
magnitude so as to enable an unbiased estimation. However, for nodes far away from the sink withlow channel gains, it is not possible to avoid misalignment in signal magnitude.
Now, Suhua Tang and colleagues at University of Electro-Communications, Tokyo, University of
Science and Technology, China, and Xi’an Jiaotong University, China, describe their solution to themisalignment problem using the amplify-and-forward (AF) based relay mechanism.
In their paper, Tang and colleagues first present the general relay model for AirComp, andinvestigated the possibility of using a simple relay (SimRelay) approach in which a node either
directly transmits its signal to a sink or via a relay node, but not both. They emphasize that, “relaytransmission power increases with the number of nodes that use the relay node.”
The researchers also proposed a coherent relay (CohRelay) approach, in which a node can divide its
power to transmit its signal to both the relay and the sink, and the replicas of its signal are coherently
combined together at the sink. They also discuss the tradeoff between computation error andtransmission power.
The CohRelay approach greatly reduced the computation error, as well as reducing the relaytransmission power and the overall transmission power, which is a major step forward towards thepractical applications of AirComp.

Reference:・ Authors: (4) Suhua Tang, Huarui Yin, Chao Zhang, and Sadao Obana.
・ Title of original paper: Reliable over-the-air computation by amplify-and-forward based relay.
・ Journal, volume, pages and year: IEEE Access, vol. 9, pp. 53333-53342, Apr. 2021.
・ Digital Object Identifier (DOI): 10.1109/ACCESS.2021.3070901
・ Affiliations: Department of Computer and Network Engineering, Graduate School of Informatics
and Engineering, The University of Electro-Communications.
・ Department website: http://www.tang.cs.uec.ac.jp/index-e.html

The University of Electro-Communications 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585© 2021 The University of Electro-Communications.

Vol.28, June 2021

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Figure caption: Relay for AirComp, an analogy to a conventional relay network.

The University of Electro-Communications 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585© 2021 The University of Electro-Communications.

Vol.28, June 2021

Innovative building blocks for the quantum internet: All fiber platform for quantum photonic
processing on tapered optical fibers

Research on quantum photonics is focused on the coherent control of individual quanta of light
known as photons. Such control of light is an important step towards the realization of opticalquantum networks and ultimately the so-called quantum internet.
Notably, single photons can be efficient carriers of quantum information, and they travel at the speedof light incurring the minimal of interaction with the medium through which they move. However,these same physical characteristics lead to difficulties in isolating (generation) and controlling(storage/retrieval/switching) single photons.
A solution to this problem is the development of means to control photons using atomic media. In
this approach, one key requirement is to be able to confine atoms and photons to subwavelength
dimensions, that is, within a single atom absorption cross-section to realize efficient light-matterinteraction at the single quanta level. Therefore, there has been increasing interest in the strong
confinement of photonic modes in nanophotonic waveguides and resonators that exhibit quantum
electrodynamics (QED) effects.
Now, Kali Prasanna Nayak and colleagues at the University of Electro-Communications, Tokyo, aredeveloping a unique all-fiber platform for quantum photonics applications using tapered
subwavelength diameter waist optical nanofibers.
The key feature of the UEC optical nanofiber technology is that the optical field is tightly confined in
the transverse direction while propagating over long distances as a guided mode and enabling strong
interaction with the surrounding medium in the evanescent region. This characteristic has led tounique possibilities for manipulating single atoms (solid-state quantum emitters) and fiber-guided
photons. Furthermore, implementing even moderate longitudinal confinement in nanofiber cavities
has enabled the strong coupling regime of cavity QED where coherent light-matter interaction can berealized at the single quanta level.
Based on their achievements to-date, Nayak and colleagues are developing both quantum interfaces
between trapped (laser-cooled) single atoms and fiber-guided photons using photonic crystal
nanofiber cavities, and fiber-coupled quantum light sources using hybrid systems of single quantum
dots deposited on nanofibers. These fiber-coupled quantum photonics platforms show promise asbuilding blocks for optical quantum processors and can be easily integrated into optical quantum
networks.
The University of Electro-Communications 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585© 2021 The University of Electro-Communications.

Vol.28, June 2021

Figure caption: Schematic diagram of a nanofiber-based quantum interface. The nanofiber is locatedat the waist of a tapered single mode optical fiber. The nanofiber cavity (ONF Cavity) is formed byfabricating two photonic crystal (1-D PhC) Bragg mirrors on the nanofiber using femtosecond laser
ablation. Single atoms are trapped and interfaced to the nanofiber cavity using a tightly focused
optical dipole trap (single atom tweezer).
Reference:・ Authors: Kali P. Nayak, Mark Sadgrove, Ramachandrarao Yalla,
Fam Le Kien and Kohzo Hakuta
・ Title of original paper: Nanofiber quantum photonics
・ Journal, volume, pages and year: J. Opt. 20, 073001 (2018).
・ Digital Object Identifier (DOI): 10.1088/2040-8986/aac35e
・ Affiliations: Department of Engineering Science, University ofElectro-Communications.
Department website: http://kjk.office.uec.ac.jp/Profiles/56/0005533/prof_e.html

The University of Electro-Communications 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585© 2021 The University of Electro-Communications.

Vol.28, June 2021

Bacteria in the spotlight: Bacterial community exhibits only counterclockwise movement

The collective motion of self-driven particles is a fascinating area of research in physics andbiology. In the case of bacteria, macroscopic behavior emerges through the movement of millions ofbacterial cells self-propelled by flagellar rotation.
Here, Daisuke Nakane and colleagues report on the observation of a new mode of collective motion
in non-flagellated soil bacterium known as Flavobacterium Johnsonian.
The researchers discovered that when bacterial cells were spotted on an agar plate with a low level ofnutrients, the bacterial community exhibited vortex patterns that spontaneously appeared as lattices
and integrated into a large-scale circular plate.
Notably, the large-scale circular plate exhibited unidirectional rotation in a counterclockwise mannerwithout exception.
Nakane and his colleagues postulate that “this behavior might be an efficient strategy for cells of thisspecies to find nutrients.”
Reference:・ Authors: Daisuke Nakane1, Shoko Odaka2, Kana Suzuki2, and Takayuki Nishizaka2.
・ Title of original paper: Large-scale vortices with dynamic rotation emerged from monolayercollective motion of gliding Flavobacteria
・ Journal, volume, pages and year: Journal of Bacteriology 203, e00073-21. (2021).
・ Digital Object Identifier (DOI): 10.1128/JB.00073-21
・ Affiliations: 1Department of Engineering Science, The University of Electro-Communications,2
Department of Physics, Gakushuin University
・ Department website: https://nakane-lab.amebaownd.com/

Figure caption: Vortex patterns of bacteria
https://www.youtube.com/watch?v=auhm-uGOPDAThe University of Electro-Communications 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585© 2021 The University of Electro-Communications.

Vol.28, June 2021

How and why do bacteria move?

Daisuke Nakane, Assistant Professor, Department ofEngineering Science, UEC Tokyo.
Here, Daisuke Nakane describes his research interests
and recent results on how and why bacteria move.
It is well known that bacteria are one of the simplest
forms of life on Earth. They live everywhere, and have a great impact on our lives, including health,agriculture, and environment.
“Bacteria are too small to be seen directly,” says Nakane. “My research is focused on visualizing
bacterial cells and their biological motion using optical microscopy to understand their behavior on amolecular level.”
The molecular systems of bacterial cell motility are completely different from that of humans because
they are based on eukaryotic motor proteins such as myosin, kinesin, and dynein.
Some examples in the video show swimming motility driven by rotating flagellar filaments aspropellers. This is one of the most famous and well-studied forms of molecular machinery. The
flagellar filament is only 20 nm in diameter and rotates at 50 Hz in this species.
Nakane has visualized its rotation with high spatiotemporal resolution with optical microscopes. This
had led to new scientific discoveries, such as the observation that some bacteria exhibit a new
swimming style of flagella wrapping. When the flagellar filaments switch their rotation towards theother side, the cell wraps the filaments around their bodies and moves like a drilling tank.
More examples include a bacterial Spider-Man, caterpillars, helices and kinks, and walking bacteriawith legs.
“Research on bacteria motility over the last 20 years has shown that they exhibit a surprisingly diverse
range of movements,” explains Nakane. “This dynamic behavior was observed mainly underlaboratory conditions. We do not actually know to what degree these movements contribute to theirsurvival in real environments. I think that the next challenge is to answer the question as to whybacteria move.”

The University of Electro-Communications 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585© 2021 The University of Electro-Communications.

Vol.28, June 2021

Nakane’s recent work includes observations of the collective motion of bacteria. Experiments ofbacterial surface movement in Petri dishes showed bacteria to move in striking patterns of vortices
that rotate only in the counterclockwise direction. Given that this is triggered by starvation, the vortex
pattern might be a new strategy by bacteria to find nutrients for their survival. Details about thisresearch are given in the Journal of Bacteriology [1].
“You can even see microbes even in a Zoom meeting by using with a smart phone,” demonstrates
Nakane in the video using a small chamber containing thousands of microbes. “When I put a drop ofwater on the camera, it turns into a microscope, and enables us to visualize the individual cell
behavior directly. My lab has is new being established in October 2020. I look forward to collaboratingwith researchers in many other fields. Let’s enjoy science together.”
Keywords of Daisuke Nakane’s research are biophysics, microbiology, and optical microscopy.

Reference[1] Daisuke Nakane, Shoko Odaka, Kana Suzuki, and Takayuki Nishizaka
Large-scale vortices with dynamic rotation emerged from monolayer collective motion of gliding
Flavobacteria, J. Bacteriol. 203: e00073-21. (2021)
DOI: 10.1128/JB.00073-21
URL: https://journals.asm.org/doi/abs/10.1128/JB.00073-21

The University of Electro-Communications 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585© 2021 The University of Electro-Communications.

Vol.28, June 2021

Insights into modern reliability engineering

Lu Jin, Associate Professor at the Department of Informatics, UEC Tokyo“My research is based on reliability engineering,” says Lu Jin, an associate professor at the Department of Informatics,
UEC Tokyo. “I am working on maintenance planning to study a wide range of systems for ensuring the safety andsecurity of our society. The interest of my research is developing decision-making models for realizing more flexible
and efficient maintenance plan while maintaining high reliability and safety.”
Jin is developing decision-making models for systems focused on optimizing problems for maintenance plans suchas periodic maintenance and condition monitoring maintenance.
Specifically, Jin wants to reduce maintenance costs while maintaining reliability levels by dynamically adjusting andcontrolling maintenance plans based on monitoring information on operating systems. A maintenance plan thatuses the Markov decision process as the core model, takes into consideration the effects of direct and indirect
measurement of system deterioration, measurement accuracy, changes in the operating environment, and so on,
and yields a trade-off between maintenance costs and failure losses.
Recent research results on maintenance decisions that take into account the uncertainty and changes in information
being monitored.
・ Effective utilization of maintenance opportunities with incomplete information(Awarded prizes at the Japan Quality Control Society and ANQ2019 international conference. Scheduled to be
published in TQS Journal)
・ Economically optimal maintenance plan based on continuous deterioration process (maintenance planning)・ Periodic inspection plan with variable cycles“I'm also working on joint research with colleagues at Mälardalens University in Sweden, on using existing
maintenance optimization methods in other fields such as pricing options and examining investment strategies. Thisis an exciting area of research.”
References

Optimizing Opportunistic Maintenance by Using a Semi-Markov Decision Process, Odajima, Y. and Jin, L. Total
Quality Science 2021 (In press)



Optimal Policy for Periodic Inspections with Flexible Imperfect Inspection Frequencies, Jin, L., Koyama, N. andYamamoto, W. Total Quality Science 4/ 3, 128-137, 2018.

Approximate Log-Linear Cumulative Exposure Time Scale Model by Joint Moment Generating Function of
Covariates, Yamamoto, W. and Jin, L. Frontiers in Statistical Quality Control 12, 327-339, 2018.
The University of Electro-Communications 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585© 2021 The University of Electro-Communications.

Vol.28, June 2021



Optimal Inspection Policy for Scheduled Maintenance of Aging Systems, Jin, L. and Yamamoto, W. International
Journal of Industrial Engineering: Theory, Applications and Practice 24/ 4, 99-111, 2017.



Optimal Control Limit Policy for Age-Dependent Deteriorating Systems, Jin, L., Bayarsaikhan, U. and Suzuki, K.
Journal of Risk and Reliability 230/ 1, 34-43, 2016. DOI:10.1177/1748006X15589208



Optimal Maintenance Policy for Aging Systems Under Non-stationary Markov Deterioration, Jin, L. Journal of
the Japanese Society for Quality Control 45/ 4, 65-73, 2015.

The University of Electro-Communications 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585© 2021 The University of Electro-Communications.

Vol.28, June 2021

The University of Electro-Communications 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585© 2021 The University of Electro-Communications.

Vol.28, June 2021

Joint demonstration experiment on visualizing carbon dioxide concentration inside Chofu City
Hall with eight IoT sensors

1 June 2021
From 1 June 2021, the University of Electro-Communications (UEC Tokyo) and Chofu City plan to
jointly carry out a demonstration experiment to visualize the carbon dioxide concentration in Chofu
City Hall and maintain good ventilation as part of an industry-academia-government collaboration.
The demonstration will utilize high-precision compact carbon dioxide sensor developed by the
Tanaka-Ishigaki Laboratory (Department of Informatics) and Yokogawa Laboratory (Info-Powered
Energy System Research Center) at UEC Tokyo.
The sensors will be installed on the 1st to 3rd floors of Chofu City Hall, where many residents visit.
The sensors will measure the surrounding carbon dioxide concentration and "visualize" the recorded
values by displaying the color and numerical value of the sensors. If the measured value exceeds thestandard value of 1,000 ppm, Chofu City staff will carry out ventilation in each of the surrounding
places.
Furthermore, if the measured value exceeds the standard value, an e-mail alert will be automaticallysent from UEC that is collecting data via the wireless networks to the section in charge of Chofu City,and the person in charge will implement procedures for proper ventilation.

Visualized image of carbon dioxide concentration (composite photo)

The University of Electro-Communications 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585© 2021 The University of Electro-Communications.

Vol.28, June 2021

The University of Electro-Communications (UEC) in Tokyo
is a small, luminous university at the forefront of pure and applied sciences, engineering, andtechnology research. Its roots go back to the Technical Institute for Wireless Commutations,which was established in 1918 by the Wireless Association to train so-called wireless engineers
in maritime communications in response to the Titanic disaster in 1912. In 1949, the UEC wasestablished as a national university by the Japanese Ministry of Education, and moved in 1957
from Meguro to its current Chofu campus Tokyo.
With approximately 4,000 students and 350 faculty, UEC is regarded as a small university, butwith particular expertise in wireless communications, laser science, robotics, informatics, andmaterial science, to name just a few areas of research.
The UEC was selected for the Ministry of Education, Culture, Sports, Science and Technology (MEXT)
Program for Promoting the Enhancement of Research Universities as a result of its strengths inthree main areas: optics and photonics research, where we are number one for the numberof joint publications with foreign researchers; wireless communications, which reflects ourroots; and materials-based research, particularly on fuel cells.
International Public Relations
The University of Electro-Communications
1-5-1 Chofugaoka, Chofu, Tokyo 182-8585
E- mail : kokusai-k@office.uec.ac.jp
Website: http://www.uec.ac.jp/eng/

The University of Electro-Communications 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585© 2021 The University of Electro-Communications.