IEEE Consumer Electronics Magazine - March 2018 - 27

the peak load, space utilization, and hardware resource use.
Moreover, it allows the data stream coming from the IoT nodes
to be inspected. The backup service periodically burns the virtual machine snapshots to restore an existing configuration of
the services. Finally, the restful application programming interface service allows third-party applications (e.g., the numerical
analysis described in the "Numerical Analysis" section) to
retrieve raw and/or aggregated sensing information stored on
the databases to produce other analyses and statistics.

NUMERICAL ANALYSIS
Through OMA techniques, the modal proprieties of a structure are extracted by measuring the vibration response only,
assuming that the operational loads (e.g., wind and traffic) are
not disturbances but rather replace artificial excitation. In the
developed system, the enhanced frequency domain decomposition technique is used, and this OMA method estimates the
modal parameters by a singular value decomposition of the
spectral density matrix of the output data recorded [19].
The finite-element model of the structure is made by
NOSA-ITACA code [20], a freeware/open-source software for
computational mechanics with the aim of disseminating the
use of mathematical models and numerical tools in the field of
cultural heritage. In particular, it can model the mechanical
behavior of masonry constructions by the constitutive equation in which masonry is described as a nonlinear elastic
material with zero tensile strength and finite compressive or
bounded resistance.

SYSTEM VALIDATION
To validate the system described in the "SMS: Long-Term
Structural Monitoring System" section, we first verified the
proper operation of data acquisition and signal processing
and then confirmed the system operation performance. For
this purpose, we built a wooden-framed structure in the laboratory. The prototype, shown in Figure 3(c) and schematized
in Figure 3(a), consists of two columns with a rectangular
cross section rigidly connected to an upper rectangular crosssection wooden beam.
All connections are ensured through steel angle brackets and
bolts, which approximates a perfect joint; this setup prevents any
relative rotation between the elements of the wooden structure,
and the structure can oscillate at a given frequency simply by
varying the mass of the structure by adding or removing sandbags on the top of the structure. As shown in Figure 3(b), we
built the finite-element model of the structure through NOSAITACA software (see the "Numerical Analysis" section). The
tests were performed for different values of the mass and compared with the results of the numerical simulations. We then
conducted eight tests with masses ranging from 1 to 4.5 kg.
To evaluate the stability of the system and the deviation
from simulations, we also performed four experiments for
each test. The results of one test, T2.0 at given mass of 2 kg,
are shown in Figure 3. In particular, Figure 3(d) illustrates the
comparison between the measured acceleration by the system
and the numerical NOSA-ITACA simulations for each exper-

iment. We analyzed the measured accelerations in the frequency domain to calculate the natural mode of the structure.
The natural frequencies were then obtained as the maximum
of the Fourier transform amplitudes, and all comparisons
show good agreement between the experimental data and the
numerical simulations. For example, we observed a measured
natural frequency of 3.32 Hz for T2.0 [Figure 3(e)], which compares with 3.31 Hz, when evaluated with the NOSA-ITACA
code. The relative error amounts to roughly 0.3% for T2.0,
and, while considering the entirety of the performed tests, the
error committed is less than 1.3%.
To consider the system operation performance, we evaluated the reliability of the SMS system. Reliability has been
determined as the ability of the system to operate without
causing malfunction. To evaluate the health status of a structure, the elaboration of time series collected over several
months or even years is needed. A continuous acquisition for
SHM applications is unsuitable, since this leads to high energy consumption without adding much more information
about potential structural damages.
In our case, we deployed the IoT nodes on San Frediano's bell
tower (as shown in the "Evaluation of the Structural Behavior
of the Bell Tower" section) and monitored it for six months, performing data gathering for 30 min per week. While monitoring, there were no system failures, and each of the six WS nodes
correctly reported the acceleration on the three axes, jointly with
temperature and humidity values, for 5 million samples.
Furthermore, we compared the energy consumption of our
system with the solutions proposed in [10] and [13]. The
results have shown that our NTP-based synchronization method saves up to 15% of the energy, compared to the ad hoc
protocols proposed in [10]. Moreover, comparing the energy
consumed to transmit the compressed data, as proposed in
[13], with that energy consumed to transmit uncompressed
data, we have observed a 40% rate of energy preservation.
In addition, these data refer to our case study, i.e., a short-range,
single-hop communication scenario with an available Internet connection.

EXPERIMENTAL CAMPAIGN AND DISCUSSION
The bell tower of San Frediano church in Lucca, Italy, as
shown in Figure 4(b), is a masonry tower 52 m high that was
built in the 11th century. The thickness of its walls ranges
from 2.1 to 1.6 m from the base to the top, respectively, and
inside the tower there are no structural elements apart from
the staircase that runs along the perimeter, which is 38-m
high. The staircase allows access to the bell floor, as indicated
by section 2 in Figure 4(a), from which it is possible to reach
a wooden floor (section 1) that supports the bell infrastructure.
In June 2015, a preliminary experimental campaign was
performed by sophisticated and high-precision instrumentation that is usually employed in seismic monitoring networks
that were made available by the Osservatorio Sismologico of
Arezzo. The recorded data processing by an OMA technique
allowed us to collect a large amount of information about the
modal properties of the tower reported in Figure 4(c), and a
march 2018

^

IEEE Consumer Electronics Magazine

27



Table of Contents for the Digital Edition of IEEE Consumer Electronics Magazine - March 2018

Contents
IEEE Consumer Electronics Magazine - March 2018 - Cover1
IEEE Consumer Electronics Magazine - March 2018 - Cover2
IEEE Consumer Electronics Magazine - March 2018 - Contents
IEEE Consumer Electronics Magazine - March 2018 - 2
IEEE Consumer Electronics Magazine - March 2018 - 3
IEEE Consumer Electronics Magazine - March 2018 - 4
IEEE Consumer Electronics Magazine - March 2018 - 5
IEEE Consumer Electronics Magazine - March 2018 - 6
IEEE Consumer Electronics Magazine - March 2018 - 7
IEEE Consumer Electronics Magazine - March 2018 - 8
IEEE Consumer Electronics Magazine - March 2018 - 9
IEEE Consumer Electronics Magazine - March 2018 - 10
IEEE Consumer Electronics Magazine - March 2018 - 11
IEEE Consumer Electronics Magazine - March 2018 - 12
IEEE Consumer Electronics Magazine - March 2018 - 13
IEEE Consumer Electronics Magazine - March 2018 - 14
IEEE Consumer Electronics Magazine - March 2018 - 15
IEEE Consumer Electronics Magazine - March 2018 - 16
IEEE Consumer Electronics Magazine - March 2018 - 17
IEEE Consumer Electronics Magazine - March 2018 - 18
IEEE Consumer Electronics Magazine - March 2018 - 19
IEEE Consumer Electronics Magazine - March 2018 - 20
IEEE Consumer Electronics Magazine - March 2018 - 21
IEEE Consumer Electronics Magazine - March 2018 - 22
IEEE Consumer Electronics Magazine - March 2018 - 23
IEEE Consumer Electronics Magazine - March 2018 - 24
IEEE Consumer Electronics Magazine - March 2018 - 25
IEEE Consumer Electronics Magazine - March 2018 - 26
IEEE Consumer Electronics Magazine - March 2018 - 27
IEEE Consumer Electronics Magazine - March 2018 - 28
IEEE Consumer Electronics Magazine - March 2018 - 29
IEEE Consumer Electronics Magazine - March 2018 - 30
IEEE Consumer Electronics Magazine - March 2018 - 31
IEEE Consumer Electronics Magazine - March 2018 - 32
IEEE Consumer Electronics Magazine - March 2018 - 33
IEEE Consumer Electronics Magazine - March 2018 - 34
IEEE Consumer Electronics Magazine - March 2018 - 35
IEEE Consumer Electronics Magazine - March 2018 - 36
IEEE Consumer Electronics Magazine - March 2018 - 37
IEEE Consumer Electronics Magazine - March 2018 - 38
IEEE Consumer Electronics Magazine - March 2018 - 39
IEEE Consumer Electronics Magazine - March 2018 - 40
IEEE Consumer Electronics Magazine - March 2018 - 41
IEEE Consumer Electronics Magazine - March 2018 - 42
IEEE Consumer Electronics Magazine - March 2018 - 43
IEEE Consumer Electronics Magazine - March 2018 - 44
IEEE Consumer Electronics Magazine - March 2018 - 45
IEEE Consumer Electronics Magazine - March 2018 - 46
IEEE Consumer Electronics Magazine - March 2018 - 47
IEEE Consumer Electronics Magazine - March 2018 - 48
IEEE Consumer Electronics Magazine - March 2018 - 49
IEEE Consumer Electronics Magazine - March 2018 - 50
IEEE Consumer Electronics Magazine - March 2018 - 51
IEEE Consumer Electronics Magazine - March 2018 - 52
IEEE Consumer Electronics Magazine - March 2018 - 53
IEEE Consumer Electronics Magazine - March 2018 - 54
IEEE Consumer Electronics Magazine - March 2018 - 55
IEEE Consumer Electronics Magazine - March 2018 - 56
IEEE Consumer Electronics Magazine - March 2018 - 57
IEEE Consumer Electronics Magazine - March 2018 - 58
IEEE Consumer Electronics Magazine - March 2018 - 59
IEEE Consumer Electronics Magazine - March 2018 - 60
IEEE Consumer Electronics Magazine - March 2018 - 61
IEEE Consumer Electronics Magazine - March 2018 - 62
IEEE Consumer Electronics Magazine - March 2018 - 63
IEEE Consumer Electronics Magazine - March 2018 - 64
IEEE Consumer Electronics Magazine - March 2018 - 65
IEEE Consumer Electronics Magazine - March 2018 - 66
IEEE Consumer Electronics Magazine - March 2018 - 67
IEEE Consumer Electronics Magazine - March 2018 - 68
IEEE Consumer Electronics Magazine - March 2018 - 69
IEEE Consumer Electronics Magazine - March 2018 - 70
IEEE Consumer Electronics Magazine - March 2018 - 71
IEEE Consumer Electronics Magazine - March 2018 - 72
IEEE Consumer Electronics Magazine - March 2018 - 73
IEEE Consumer Electronics Magazine - March 2018 - 74
IEEE Consumer Electronics Magazine - March 2018 - 75
IEEE Consumer Electronics Magazine - March 2018 - 76
IEEE Consumer Electronics Magazine - March 2018 - 77
IEEE Consumer Electronics Magazine - March 2018 - 78
IEEE Consumer Electronics Magazine - March 2018 - 79
IEEE Consumer Electronics Magazine - March 2018 - 80
IEEE Consumer Electronics Magazine - March 2018 - 81
IEEE Consumer Electronics Magazine - March 2018 - 82
IEEE Consumer Electronics Magazine - March 2018 - 83
IEEE Consumer Electronics Magazine - March 2018 - 84
IEEE Consumer Electronics Magazine - March 2018 - 85
IEEE Consumer Electronics Magazine - March 2018 - 86
IEEE Consumer Electronics Magazine - March 2018 - 87
IEEE Consumer Electronics Magazine - March 2018 - 88
IEEE Consumer Electronics Magazine - March 2018 - 89
IEEE Consumer Electronics Magazine - March 2018 - 90
IEEE Consumer Electronics Magazine - March 2018 - 91
IEEE Consumer Electronics Magazine - March 2018 - 92
IEEE Consumer Electronics Magazine - March 2018 - 93
IEEE Consumer Electronics Magazine - March 2018 - 94
IEEE Consumer Electronics Magazine - March 2018 - 95
IEEE Consumer Electronics Magazine - March 2018 - 96
IEEE Consumer Electronics Magazine - March 2018 - 97
IEEE Consumer Electronics Magazine - March 2018 - 98
IEEE Consumer Electronics Magazine - March 2018 - 99
IEEE Consumer Electronics Magazine - March 2018 - 100
IEEE Consumer Electronics Magazine - March 2018 - 101
IEEE Consumer Electronics Magazine - March 2018 - 102
IEEE Consumer Electronics Magazine - March 2018 - 103
IEEE Consumer Electronics Magazine - March 2018 - 104
IEEE Consumer Electronics Magazine - March 2018 - 105
IEEE Consumer Electronics Magazine - March 2018 - 106
IEEE Consumer Electronics Magazine - March 2018 - 107
IEEE Consumer Electronics Magazine - March 2018 - 108
IEEE Consumer Electronics Magazine - March 2018 - 109
IEEE Consumer Electronics Magazine - March 2018 - 110
IEEE Consumer Electronics Magazine - March 2018 - 111
IEEE Consumer Electronics Magazine - March 2018 - 112
IEEE Consumer Electronics Magazine - March 2018 - 113
IEEE Consumer Electronics Magazine - March 2018 - 114
IEEE Consumer Electronics Magazine - March 2018 - 115
IEEE Consumer Electronics Magazine - March 2018 - 116
IEEE Consumer Electronics Magazine - March 2018 - 117
IEEE Consumer Electronics Magazine - March 2018 - 118
IEEE Consumer Electronics Magazine - March 2018 - 119
IEEE Consumer Electronics Magazine - March 2018 - 120
IEEE Consumer Electronics Magazine - March 2018 - Cover3
IEEE Consumer Electronics Magazine - March 2018 - Cover4
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_20240102
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_20231112
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_20230910
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_20230708
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_20230506
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_20230304
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_20230102
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_20221112
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_20220910
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_20220708
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_20220506
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_20220304
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_20220102
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_20211112
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_20210910
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_20210708
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_20210506
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_20210304
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_202010
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_202009
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_202007
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_202004
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_202003
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_202001
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_201910
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_201909
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_201907
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_201905
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_201903
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_201901
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_201811
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_201809
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_201807
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_201805
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_201803
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_july2017
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_april2017
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_january2017
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_october2016
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_july2016
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_april2016
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_january2016
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_october2015
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_july2015
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_april2015
https://www.nxtbook.com/nxtbooks/ieee/consumerelectronics_january2015
https://www.nxtbookmedia.com