2,658 research outputs found
A Deployment of Fine-Grained Sensor Network and Empirical Analysis of Urban Temperature
Temperature in an urban area exhibits a complicated pattern due to complexity of infrastructure. Despite geographical proximity, structures of a group of buildings and streets affect changes in temperature. To investigate the pattern of fine-grained distribution of temperature, we installed a densely distributed sensor network called UScan. In this paper, we describe the system architecture of UScan as well as experience learned from installing 200 sensors in downtown Tokyo. The field experiment of UScan system operated for two months to collect long-term urban temperature data. To analyze the collected data in an efficient manner, we propose a lightweight clustering methodology to study the correlation between the pattern of temperature and various environmental factors including the amount of sunshine, the width of streets, and the existence of trees. The analysis reveals meaningful results and asserts the necessity of fine-grained deployment of sensors in an urban area
UrbanFM: Inferring Fine-Grained Urban Flows
Urban flow monitoring systems play important roles in smart city efforts
around the world. However, the ubiquitous deployment of monitoring devices,
such as CCTVs, induces a long-lasting and enormous cost for maintenance and
operation. This suggests the need for a technology that can reduce the number
of deployed devices, while preventing the degeneration of data accuracy and
granularity. In this paper, we aim to infer the real-time and fine-grained
crowd flows throughout a city based on coarse-grained observations. This task
is challenging due to two reasons: the spatial correlations between coarse- and
fine-grained urban flows, and the complexities of external impacts. To tackle
these issues, we develop a method entitled UrbanFM based on deep neural
networks. Our model consists of two major parts: 1) an inference network to
generate fine-grained flow distributions from coarse-grained inputs by using a
feature extraction module and a novel distributional upsampling module; 2) a
general fusion subnet to further boost the performance by considering the
influences of different external factors. Extensive experiments on two
real-world datasets, namely TaxiBJ and HappyValley, validate the effectiveness
and efficiency of our method compared to seven baselines, demonstrating the
state-of-the-art performance of our approach on the fine-grained urban flow
inference problem
Development and Analysis of Low-Cost IoT Sensors for Urban Environmental Monitoring
The accelerated pace of urbanization is having a major impact over the world’s environment. Although urban dwellers have higher living standards and can access better public services as compared to their rural counterparts, they are usually exposed to poor environmental conditions such as air pollution and noise. In order for municipalities and citizens to mitigate the negative effects of pollution, the monitoring of certain parameters, such as air quality and ambient sound levels, both in indoor and outdoor locations, has to be performed. The current paper presents a complete solution that allows the monitoring of ambient parameters such as Volatile Organic Compounds, temperature, relative humidity, pressure, and sound intensity levels both in indoor and outdoor spaces. The presented solution comprises of low-cost, easy to deploy, wireless sensors and a cloud application for their management and for storing and visualizing the recorded data
Not All Wireless Sensor Networks Are Created Equal: A Comparative Study On Tunnels
Wireless sensor networks (WSNs) are envisioned for a number of application scenarios. Nevertheless, the few in-the-field experiences typically focus on the features of a specific system, and rarely report about the characteristics of the target environment, especially w.r.t. the behavior and performance of low-power wireless communication. The TRITon project, funded by our local administration, aims to improve safety and reduce maintenance costs of road tunnels, using a WSN-based control infrastructure. The access to real tunnels within TRITon gives us the opportunity to experimentally assess the peculiarities of this environment, hitherto not investigated in the WSN field. We report about three deployments: i) an operational road tunnel, enabling us to assess the impact of vehicular traffic; ii) a non-operational tunnel, providing insights into analogous scenarios (e.g., underground mines) without vehicles; iii) a vineyard, serving as a baseline representative of the existing literature. Our setup, replicated in each deployment, uses mainstream WSN hardware, and popular MAC and routing protocols. We analyze and compare the deployments w.r.t. reliability, stability, and asymmetry of links, the accuracy of link quality estimators, and the impact of these aspects on MAC and routing layers. Our analysis shows that a number of criteria commonly used in the design of WSN protocols do not hold in tunnels. Therefore, our results are useful for designing networking solutions operating efficiently in similar environments
A survey of urban drive-by sensing: An optimization perspective
Pervasive and mobile sensing is an integral part of smart transport and smart
city applications. Vehicle-based mobile sensing, or drive-by sensing (DS), is
gaining popularity in both academic research and field practice. The DS
paradigm has an inherent transport component, as the spatial-temporal
distribution of the sensors are closely related to the mobility patterns of
their hosts, which may include third-party (e.g. taxis, buses) or for-hire
(e.g. unmanned aerial vehicles and dedicated vehicles) vehicles. It is
therefore essential to understand, assess and optimize the sensing power of
vehicle fleets under a wide range of urban sensing scenarios. To this end, this
paper offers an optimization-oriented summary of recent literature by
presenting a four-step discussion, namely (1) quantifying the sensing quality
(objective); (2) assessing the sensing power of various fleets (strategic); (3)
sensor deployment (strategic/tactical); and (4) vehicle maneuvers
(tactical/operational). By compiling research findings and practical insights
in this way, this review article not only highlights the optimization aspect of
drive-by sensing, but also serves as a practical guide for configuring and
deploying vehicle-based urban sensing systems.Comment: 24 pages, 3 figures, 4 table
Performance Evaluation of Energy-Autonomous Sensors Using Power-Harvesting Beacons for Environmental Monitoring in Internet of Things (IoT)
Environmental conditions and air quality monitoring have become crucial today due to the undeniable changes of the climate and accelerated urbanization. To efficiently monitor environmental parameters such as temperature, humidity, and the levels of pollutants, such as fine particulate matter (PM2.5) and volatile organic compounds (VOCs) in the air, and to collect data covering vast geographical areas, the development of cheap energy-autonomous sensors for large scale deployment and fine-grained data acquisition is required. Rapid advances in electronics and communication technologies along with the emergence of paradigms such as Cyber-Physical Systems (CPSs) and the Internet of Things (IoT) have led to the development of low-cost sensor devices that can operate unattended for long periods of time and communicate using wired or wireless connections through the Internet. We investigate the energy efficiency of an environmental monitoring system based on Bluetooth Low Energy (BLE) beacons that operate in the IoT environment. The beacons developed measure the temperature, the relative humidity, the light intensity, and the CO2 and VOC levels in the air. Based on our analysis we have developed efficient sleep scheduling algorithms that allow the sensor nodes developed to operate autonomously without requiring the replacement of the power supply. The experimental results show that low-power sensors communicating using BLE technology can operate autonomously (from the energy perspective) in applications that monitor the environment or the air quality in indoor or outdoor settings
Spatial modelling of air pollution for open smart cities
A thesis submitted in partial fulfillment of the requirements for the degree of Doctor in Information Management, specialization in Geographic Information SystemsHalf of the world’s population already lives in cities, and by 2050 two-thirds of the
world’s population are expected to further move into urban areas. This urban growth
leads to various environmental, social and economic challenges in cities, hampering
the Quality of Life (QoL). Although recent trends in technologies equip us with
various tools and techniques that can help in improving quality of life, air pollution
remains the ‘biggest environmental health risk’ for decades, impacting individuals’
quality of life and well-being according to World Health Organisation (WHO). Many
efforts have been made to measure air quality, but the sparse arrangement of
monitoring stations and the lack of data currently make it challenging to develop
systems that can capture within-city air pollution variations. To solve this, flexible
methods that allow air quality monitoring using easily accessible data sources at the
city level are desirable. The present thesis seeks to widen the current knowledge
concerning detailed air quality monitoring by developing approaches that can help
in tackling existing gaps in the literature. The thesis presents five contributions
which address the issues mentioned above. The first contribution is the choice of
a statistical method which can help in utilising existing open data and overcoming
challenges imposed by the bigness of data for detailed air pollution monitoring.
The second contribution concerns the development of optimisation method which
helps in identifying optimal locations for robust air pollution modelling in cities.
The third contribution of the thesis is also an optimisation method which helps
in initiating systematic volunteered geographic information (VGI) campaigns for
detailed air pollution monitoring by addressing sparsity and scarcity challenges
of air pollution data in cities. The fourth contribution is a study proposing the
involvement of housing companies as a stakeholder in the participatory framework
for air pollution data collection, which helps in overcoming certain gaps existing in
VGI-based approaches. Finally, the fifth contribution is an open-hardware system that
aids in collecting vehicular traffic data using WiFi signal strength. The developed
hardware can help in overcoming traffic data scarcity in cities, which limits detailed
air pollution monitoring. All the contributions are illustrated through case studies
in Muenster and Stuttgart. Overall, the thesis demonstrates the applicability of the developed approaches for enabling air pollution monitoring at the city-scale under
the broader framework of the open smart city and for urban health research
Acoustical Ranging Techniques in Embedded Wireless Sensor Networked Devices
Location sensing provides endless opportunities for a wide range of applications in GPS-obstructed environments;
where, typically, there is a need for higher degree of accuracy. In this article, we focus on robust range
estimation, an important prerequisite for fine-grained localization. Motivated by the promise of acoustic in
delivering high ranging accuracy, we present the design, implementation and evaluation of acoustic (both
ultrasound and audible) ranging systems.We distill the limitations of acoustic ranging; and present efficient
signal designs and detection algorithms to overcome the challenges of coverage, range, accuracy/resolution,
tolerance to Doppler’s effect, and audible intensity. We evaluate our proposed techniques experimentally on
TWEET, a low-power platform purpose-built for acoustic ranging applications. Our experiments demonstrate
an operational range of 20 m (outdoor) and an average accuracy 2 cm in the ultrasound domain. Finally,
we present the design of an audible-range acoustic tracking service that encompasses the benefits of a near-inaudible
acoustic broadband chirp and approximately two times increase in Doppler tolerance to achieve better performance
Air Quality Prediction in Smart Cities Using Machine Learning Technologies Based on Sensor Data: A Review
The influence of machine learning technologies is rapidly increasing and penetrating almost in every field, and air pollution prediction is not being excluded from those fields. This paper covers the revision of the studies related to air pollution prediction using machine learning algorithms based on sensor data in the context of smart cities. Using the most popular databases and executing the corresponding filtration, the most relevant papers were selected. After thorough reviewing those papers, the main features were extracted, which served as a base to link and compare them to each other. As a result, we can conclude that: (1) instead of using simple machine learning techniques, currently, the authors apply advanced and sophisticated techniques, (2) China was the leading country in terms of a case study, (3) Particulate matter with diameter equal to 2.5 micrometers was the main prediction target, (4) in 41% of the publications the authors carried out the prediction for the next day, (5) 66% of the studies used data had an hourly rate, (6) 49% of the papers used open data and since 2016 it had a tendency to increase, and (7) for efficient air quality prediction it is important to consider the external factors such as weather conditions, spatial characteristics, and temporal features
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