More Like this

1. Wake-up radio-based data forwarding for green wireless networks

   https://doi.org/10.1016/j.comcom.2020.05.046  

   Koutsandria, G. ; DiValerio, V. ; Spenza, D. ; Basagni, S. ; Petrioli, C. ( April 2020 , Computer communications)

   Green wireless networks Wake-up radio Energy harvesting Routing Markov decision process Reinforcement learning 1. Introduction With 14.2 billions of connected things in 2019, over 41.6 billions expected by 2025, and a total spending on endpoints and services that will reach well over $1.1 trillion by the end of 2026, the Internet of Things (IoT) is poised to have a transformative impact on the way we live and on the way we work [1–3]. The vision of this ‘‘connected continuum’’ of objects and people, however, comes with a wide variety of challenges, especially for those IoT networks whose devices rely on some forms of depletable energy support. This has prompted research on hardware and software solutions aimed at decreasing the depen- dence of devices from ‘‘pre-packaged’’ energy provision (e.g., batteries), leading to devices capable of harvesting energy from the environment, and to networks – often called green wireless networks – whose lifetime is virtually infinite. Despite the promising advances of energy harvesting technologies, IoT devices are still doomed to run out of energy due to their inherent constraints on resources such as storage, processing and communica- tion, whose energy requirements often exceed what harvesting can provide. The communication circuitry of prevailing radio technology, especially, consumes relevant amount of energy even when in idle state, i.e., even when no transmissions or receptions occur. Even duty cycling, namely, operating with the radio in low energy consumption ∗ Corresponding author. E-mail address: koutsandria@di.uniroma1.it (G. Koutsandria). https://doi.org/10.1016/j.comcom.2020.05.046 (sleep) mode for pre-set amounts of time, has been shown to only mildly alleviate the problem of making IoT devices durable [4]. An effective answer to eliminate all possible forms of energy consumption that are not directly related to communication (e.g., idle listening) is provided by ultra low power radio triggering techniques, also known as wake-up radios [5,6]. Wake-up radio-based networks allow devices to remain in sleep mode by turning off their main radio when no communication is taking place. Devices continuously listen for a trigger on their wake-up radio, namely, for a wake-up sequence, to activate their main radio and participate to communication tasks. Therefore, devices wake up and turn their main radio on only when data communication is requested by a neighboring device. Further energy savings can be obtained by restricting the number of neighboring devices that wake up when triggered. This is obtained by allowing devices to wake up only when they receive specific wake-up sequences, which correspond to particular protocol requirements, including distance from the destina- tion, current energy status, residual energy, etc. This form of selective awakenings is called semantic addressing [7]. Use of low-power wake-up radio with semantic addressing has been shown to remarkably reduce the dominating energy costs of communication and idle listening of traditional radio networking [7–12]. This paper contributes to the research on enabling green wireless networks for long lasting IoT applications. Specifically, we introduce a ABSTRACT This paper presents G-WHARP, for Green Wake-up and HARvesting-based energy-Predictive forwarding, a wake-up radio-based forwarding strategy for wireless networks equipped with energy harvesting capabilities (green wireless networks). Following a learning-based approach, G-WHARP blends energy harvesting and wake-up radio technology to maximize energy efficiency and obtain superior network performance. Nodes autonomously decide on their forwarding availability based on a Markov Decision Process (MDP) that takes into account a variety of energy-related aspects, including the currently available energy and that harvestable in the foreseeable future. Solution of the MDP is provided by a computationally light heuristic based on a simple threshold policy, thus obtaining further computational energy savings. The performance of G-WHARP is evaluated via GreenCastalia simulations, where we accurately model wake-up radios, harvestable energy, and the computational power needed to solve the MDP. Key network and system parameters are varied, including the source of harvestable energy, the network density, wake-up radio data rate and data traffic. We also compare the performance of G-WHARP to that of two state-of-the-art data forwarding strategies, namely GreenRoutes and CTP-WUR. Results show that G-WHARP limits energy expenditures while achieving low end-to-end latency and high packet delivery ratio. Particularly, it consumes up to 34% and 59% less energy than CTP-WUR and GreenRoutes, respectively. 

   more » « less
2. What drives our behaviors in buildings? A review on occupant interactions with building systems from the lens of behavioral theories

   https://doi.org/10.1016/j.buildenv.2020.106928  

   Arsalan Heydarian, Claire McIlvennie ( July 2020 , Building and environment)

   Occupant behavior has a significant impact on building systems’ operations and efficiency. As a result, several innovative approaches have been introduced to quantify the dynamics of occupants within indoor environments, such as interactions with different building systems and the impact of various feedback and interventions to reduce the building energy consumption. To achieve this, researchers have highlighted the importance of reducing energy consumption without impacting occupant comfort. As a result, there is an increasing body of research evaluating how different theories of behavior across a variety of disciplines can explain occupant interactions with building systems. Future progress in this area calls for an in-depth understanding of behavioral theories in explaining occupant interactions with different building systems. In this paper, we have used a structured literature review approach to investigate how different psychological, sociological, and economic theories have been applied to explain occupant interactions with heating and cooling (HVAC systems), opening windows and ventilation, lighting and shading, electronic appliances, domestic hot water, as well as energy conservation behaviors. Throughout the paper, we identify the most common theories and methodologies applied within the existing research, general findings related to how occupants interact with different building systems, as well as a number of identified gaps within the literature. Finally, we provide a discussion on directions for future research studies in this area under each building system. 

   more » « less
3. 2021 ASEE Virtual Annual Conference Content Access

   Bhattarai, B. ( July 2021 , Poster: Use of Augmented Reality (AR) and Virtual Reality(VR) to tackle 4 amongst the ”14 Grand Challenges for Engineering in the 21st Century” identified by National Academy of Engineering)

   This poster presents the use of Augmented Reality (AR) and Virtual Reality (VR) to tackle 4 amongst the “14 Grand Challenges for Engineering in the 21st Century” identified by National Academy of Engineering. AR and VR are the technologies of the present and the future. AR creates a composite view by adding digital content to a real world view, often by using the camera of a smartphone and VR creates an immersive view where the user’s view is often cut off from the real world. The 14 challenges identify areas of science and technology that are achievable and sustainable to assist people and the planet to prosper. The 4 challenges tackled using AR/VR application in this poster are: Enhance virtual reality, Advance personalized learning, Provide access to clean water, and Make solar energy affordable. The solar system VR application is aimed at tackling two of the engineering challenges: (1) Enhance virtual reality and (2) Advance personalized learning. The VR application assists the user in visualizing and understanding our solar system by using a VR headset. It includes an immersive 360 degree view of our solar system where the user can use controllers to interact with celestial bodies-related information and to teleport to different points in the space to have a closer look at the planets and the Sun. The user has six degrees of freedom. The AR application for water tackles the engineering challenge: “Provide access to clean water”. The AR water application shows information on drinking water accessibility and the eco-friendly usage of bottles over plastic cups within the department buildings inside Auburn University. The user of the application has an augmented view of drinking water information on a smartphone. Every time the user points the smartphone camera towards a building, the application will render a composite view with drinking water information associated to the building. The Sun path visualization AR application tackles the engineering challenge: “Make solar energy affordable”. The application helps the user visualize sun path at a selected time and location. The sun path is augmented in the camera view of the device when the user points the camera towards the sky. The application provides information on sun altitude and azimuth. Also, it provides the user with sunrise and sunset data for a selected day. The information provided by the application can aid the user with effective solar panel placement. Using AR and VR technology to tackle these challenges enhances the user experience. The information from these applications are better curated and easily visualized, thus readily understandable by the end user. Therefore, usage of AR and VR technology to tackle these type of engineering challenges looks promising. 

   more » « less
4. Frameworks for Student Research Engagement on Interdisciplinary Civic-Engaged Projects

   Kweon, Byoung-Suk ; Belle, Lauren ; Fisher, Kim ; Burke, Tara ; Haghtalab, Joy ; Roy, Nirupam ; Bonsignore, Elizabeth ; Sachs, Naomi ; Roberts, Jennifer. ( January 2023 , The International Network for the Science of Team Science (INSciTS))

   Broadband infrastructure in urban parks may serve crucial functions including an amenity to boost overall park use and a bridge to propagate WiFi access into contiguous neighborhoods. This project: SCC:PG Park WiFi as a BRIDGE to Community Resilience has developed a new model —Build Resilience through the Internet and Digital Greenspace Exposure, leveraging off-the-shelf WiFi technology, novel algorithms, community assets, and local partnerships to lower greenspace WiFi costs. This interdisciplinary work leverages: computer science, information studies, landscape architecture, and public health. Collaboration methodologies and relational definitions across disciplines are still nascent —especially when paired with civic-engaged, applied research. Student researchers (UG/Grad) are excellent partners in bridging disciplinary barriers and constraints. Their capacity to assimilate multiple frameworks has produced refinements to the project’s theoretical lenses and suggested novel socio-technical methodology improvements. Further, they are excellent ambassadors to community partners and stakeholders. In BRIDGE, we tested two mechanisms to augment student research participation. In both, we leveraged a classic, curriculum-based model named the Partnership for Action Learning in Sustainability program (PALS). This campus-wide, community-engaged initiative pairs faculty and students with community partners. PALS curates economic, environmental, and social sustainability challenges and scopes projects to customize appropriate coursework that addresses identified challenges. Outcomes include: literature searches, wireframes, and design plans that target solutions to civic problems. Constraints include the short semester timeframe and curriculum-learning-outcome constraints. (1) On BRIDGE, Dr. Kweon executed a semester-based Landscape Architecture PALS 400-level-studio. 18 undergraduates conducted in-class and in-field work to assess community needs and proposed design solutions for future park-wide WiFi. Research topics included: community-park history, neighborhood demographics, case-study analysis, and land-cover characteristics. The students conducted an in-Park, community engagement session —via interactive posterboard surveys, to gain input on what park amenities might be redesigned or added to promote WiFi use. The students then produced seven re-design plans; one included a café/garden, with an eco-corridor that integrated technology with nature. (2) From the classic, curriculum-based PALS model we created a summer-intensive for our five research assistants, to stimulate interdisciplinary collaboration in their research tasks and co-analysis of project data products: experimental technical WiFi-setup, community survey results, and stakeholder needs-assessments. Students met weekly with each other and team leadership, exchanged journal articles, and attended joint research events. This model shows promise for integrating students more formally into an interdisciplinary research project. An end-of-intensive focus group highlighted, from the students’ perspective, the pro/cons of this model. Results: In contrasting the two mechanisms, our results include: Model 1 is tried-and-trued and produces standardized, reliable products. However, as work is group based, student independence is limited —to explore topics/themes of interest. Civic groups are typically thrilled with the diversity of action plans produced. Model 2 provides greater independence in student-learning outcomes, fosters interdisciplinary, “dictionary-building” that can be used by the full team, deepens methodological approaches, and allows for student stipend payments. Lessons learned: intensive time frame needed more research team support and ideally should be extended, when possible, over the full project-span. UMD-IRB#1785365-4; NSF-award: 2125526. 

   more » « less
5. Energy Co-simulation of the Hybrid Cooling Control with Synthetic Thermal Preference Distributions

   Lu, S. ; Zhiang, Z. ; Hameen, E. C. ; Lartigue, B. ; Karaguzel, O. ( January 2020 , Symposium on Simulation in Architecture and Urban Design (SIMAUD 2020))

   Thermal comfort and energy efficiency are always the two most significant objectives in HVAC operations. However, for conventional HVAC systems, the pursuit of high energy efficiency may be at the expense of satisfactory thermal comfort. Therefore, even if centralized HVAC systems nowadays have higher energy efficiency than before in office buildings, most of them cannot adapt the dynamic occupant behaviors or individual thermal comfort. In order to realize high energy efficiency while still maintain satisfactory thermal environment for occupants indoors, the integrated hybrid HVAC system has been developed for years such as task-ambient conditioning system. Moreover, the occupant-based HVAC control system such as human- in-the-loop has also been investigated so that the system can be adaptive based on occupant behaviors. However, most of research related to personalized air-conditioning system only focuses on field-study with limited scale (i.e. only one office room), this paper has proposed a co- simulation model in energyplus to simulate the hybrid cooling system with synthetic thermal comfort distributions based on global comfort database I&II. An optimization framework on cooling set-point is proposed with the objective of energy performance and the constraints of thermal comfort distribution developed by unsupervised Gaussian mixture model (GMM) clustering and kernel density estimation (KDE). The co-simulation results have illustrated that with the proposed optimization algorithm and the hybrid cooling system, HVAC demand power has decreased 5.3% on average with at least 90% of occupants feeling satisfied. 

   more » « less