Robot swarms are often considered suitable for tasks that are large-scale and long-term. Large-scale missions force the robots to spread spatially. In these type of tasks, actively maintaining connectivity allows the swarm to coordinate. Similarly, long-term nature of the task requires robots to work for a long time. This is affected by the limited energy level of the robot. However current studies normally focus only on connectivity or energy awareness. Therefore, in this work, we propose an approach to tackle the problem of maintaining global connectivity (swarm-level property) considering finite battery life (individual property). We are specifically focusing on growing the communication network and keeping it alive for a long period. We construct a logical tree over the connectivity graph. The logical tree is constructed by using a subset of robots from the swarm. The tree is grown by adding robots as necessary. The tree is also periodically reconfigured to cope with dynamic robot motion. This enables the swarm to grow the tree efficiently. In addition, robots exchange their roles based on their available energy levels. This allows robots with low energy levels to navigate to dedicated charging stations for recharging thus allowing the swarm to maintain the communication network. We evaluate our approach in a wide set of experiments with a realistic robot simulator named ARGoS.

This thesis presents a collection of experimental designs that approach the problem of growing electricity consumption in homes. From the perspective of design, the intention has been to critically explore the design space of energy awareness artefacts to reinstate awareness of energy use in everyday practice. The design experiments were used as vehicles for thinking about the relationship between physical form, interaction, and social practice. The rationale behind the concepts was based on a small-scale ethnography, situated interviews, and design experience. Moreover, the thesis compares designer intention and actual user experiences of a prototype that was installed in nine homes in a residential area in Stockholm for three months. This was done in order to elicit tacit knowledge about how the concept was used in real-world domestic settings, to challenge everyday routines, and to enable both users and designers to critically reflect on artefacts and practices. From a design perspective, contributions include design approaches to communicating energy use: visualizations for showing relationships between behaviour and electricity consumption, shapes and forms to direct action, means for turning restrictions caused by energy conservation into central parts of the product experience, and ways to promote sustainable behaviour with positive driving forces based on user lifestyles. The general results indicate that inclusion is of great importance when designing energy awareness artefacts; all members of the household should be able to access, interact with, and reflect on their energy use. Therefore, design-related aspects such as placement and visibility, as well as how the artefact might affect the social interactions in the home,  become central. Additionally, the thesis argues that these types of artefacts can potentially create awareness accompanied by negative results such as stress. A challenge for the designer is to create artefacts that communicate and direct energy use in ways that are attractive and can be accepted by all household members as a possible way of life. / <p>In the electronic version of the thesis the references in some of the chapters has been corrected.</p>

Successful tracking of a mobile target with a sensor network requires effective answers to the challenges of uncertainty in the measured data, small latency in acquiring and reporting the tracking information, and compliance with the stringent constraints imposed by the scarce resources available on each sensor node: limited available power, restricted availability of the inter-node communication links, relatively moderate computational power. This thesis introduces the architecture of a hierarchical, self-organizing, two-tier, mission-specific sensor network, composed of sensors and routers, to track the trajectory and velocity of a single mobile target in a two-dimensional convex sensor field. A query-driven approach is proposed to input configuration parameters to the network, which allow sensors to self-configure into regions, and routers into tree-like structures, with the common goal of sensing and tracking the target in an energy-aware manner, and communicating this tracking data to a base station node incurring low-overhead responses, respectively. The proposed algorithms to define and organize the sensor regions, establish the data routing scheme, and create the data stream representing the real-time location/velocity of a target, are heuristic, distributed, and represent localized node collaborations. Node behaviours have been modeled using state diagrams and inter-node collaborations have been designed using straightforward messaging schemes. This work has attempted to establish that by using a query-driven approach to track a target, high-level knowledge can be injected to the sensor network self-organization processes and its following operation, which allows the implementation of an energy-efficient, low-overhead tracking scheme. The resulting system, although built upon simple components and interactions, is complex in extension, and not directly available for exact evaluation. However, it provides intuitively advantageous behaviours. / Thesis (Master, Computing) -- Queen's University, 2009-03-04 11:18:14.392

The evolution of communication networks has led us to an era where you cannot only perform surgery halfway across the world, but do so while being in the comfort of your own home. By eliminating the need for wires, wireless networks revolutionised communication networks by enabling nodes to communicate while being in a mobile state. The concept opened many doors to new applications and possibilities. Network Coding is a technique that optimises the throughput of a network by coding packets. Geo-Routing is a routing method that operates by using the geographical distances between nodes as the routing metric. Opportunistic Routing is a routing method that exploits the broadcast characteristics of wireless networks. In this thesis, we developed a routing scheme that incorporates Network Coding, Geo- Routing and energy aware conditions. It accomplishes this task by using one of the key phases constituting Opportunistic Routing. The developed routing scheme was implemented in OMNeT++. Various simulation experiments were conducted in OMNeT++ pertaining to the implemented scheme. The results indicate significant increase in performance metrics such as throughput and survivability. / Thesis (MIng (Computer and Electronic Engineering))--North-West University, Potchefstroom Campus, 2013

The evolution of communication networks has led us to an era where you cannot only perform surgery halfway across the world, but do so while being in the comfort of your own home. By eliminating the need for wires, wireless networks revolutionised communication networks by enabling nodes to communicate while being in a mobile state. The concept opened many doors to new applications and possibilities. Network Coding is a technique that optimises the throughput of a network by coding packets. Geo-Routing is a routing method that operates by using the geographical distances between nodes as the routing metric. Opportunistic Routing is a routing method that exploits the broadcast characteristics of wireless networks. In this thesis, we developed a routing scheme that incorporates Network Coding, Geo- Routing and energy aware conditions. It accomplishes this task by using one of the key phases constituting Opportunistic Routing. The developed routing scheme was implemented in OMNeT++. Various simulation experiments were conducted in OMNeT++ pertaining to the implemented scheme. The results indicate significant increase in performance metrics such as throughput and survivability. / Thesis (MIng (Computer and Electronic Engineering))--North-West University, Potchefstroom Campus, 2013

This thesis presents a comparison between a basic shortest path routing policy of the Destination-Sequence Distance Vector (DSDV) protocol and two power-aware policy variations of it. In the two modified versions, the routes are selected based on the energy available on the nodes and not only the shortest path distance to the destination. Simulations are conducted for a given situation of nodes and the energy efficiency of the three aforementioned policies are evaluated for example scenarios. First, a brief overview of the theory behind the study is presented. It consists of an description of ad hoc networking, DSDV, and our energy-aware modifications to DSDV. After the fundamental theory, the method is presented. It consists of a description of how the simulated scenarios relates to a real-world scenario and the simplifications made in the model. We present an overview of the model used for simulation and the operation of the program. This section ends with an explanation of the three simulated policies: shortest path, simple weighted and doubled weighted. When the theory behind the thesis are completed, the simulations are conducted. The results are examined and a summary of their meaning is discussed. It is explained how the assumptions effect the reliability of the study and an estimation of the accuracy of the results are presented. We find that the power-aware policy variations (simple weighted and double weighted) both achieve better network lifetime than the basic shortest path policy, at the cost of slightly longer per-packet paths. These results are encouraging and show that very simple modifications to DSDV can achieve significant gains in the network lifetime, helping users get the most out of their networks. Future investigation could try to optimize these gains.

Commercial buildings are one of the main contributors to energy consumption while both energy management and occupants’ consumption behaviour play crucial roles in how energy is consumed. This study explored the energy awareness of occupants in a commercial building with the goal to investigate how increased awareness could support behaviour change. For this purpose, a cooperative gamified visualization of energy consumption data, “EnerSpace”, is designed, implemented and evaluated. 8 occupants participated in this study who experienced a one-week baseline period and a one-week “EnerSpace” game period. In EnerSpace, the participants were divided into two teams and powered a spaceship with their energy saving respectively on a resource exploitation trip to Mars. Each participant had an avatar in the spaceship who introduced the participant’s personal consumption data. The energy conservation of the participants affects the moving speed of the spaceship and the living condition of their avatars. Participants were rewarded by a postcard sent by the avatars when reaching a destination. The results showed that the participants 1) decreased their energy consumption, 2) reported a fun and engaging experience with EnerSpace, and 3) felt motivated for energy conservation by different motives. This study indicated a potential for energy saving in a commercial building using a cooperative game. / Kommersiella byggnader är en av de främsta bidragsgivarna till energiförbrukningen, medan både energihantering och passagerarnas konsumtionsbeteende spelar en viktig roll i hur energi förbrukas. Denna studie undersökte medvetenheten om passagerare i en kommersiell byggnad med målet att undersöka hur ökad medvetenhet kunde stödja beteendets förändring. I detta syfte utformas, implementeras och utvärderas en kooperativ gammal visualisering av energiförbrukningsdata, "EnerSpace". 8 personer deltog i den här studien som upplevde en veckors baslinjeperiod och en veckas "EnerSpace" spelperiod. I EnerSpace delades deltagarna i två lag och drev ett rymdskepp med respektive energibesparing på en resursutnyttjandesresa till Mars. Varje deltagare hade en avatar i rymdskeppet som introducerade deltagarens personliga konsumtionsdata. Deltagarnas energibesparande påverkar rymdskeppens rörelsehastighet och deras avatars levnadsförhållande. Deltagarna belönades med ett vykort skickat av avatarer när de kom till en destination. Resultaten visade att deltagarna 1) minskade sin energiförbrukning, 2) rapporterade en rolig och engagerande erfarenhet av EnerSpace, och 3) kände sig motiverade för energibesparing med olika motiv. Denna studie indikerade en potential för energibesparing i en kommersiell byggnad med hjälp av en kooperativ gammal visualisering.

Data visualization has the power to portray an informative message when designed with the end user in mind. Energy data visualizations must be tailored to the resident's energy, graphical, and data literacy level. A resident's energy, graphical, and data literacy level depicts their understanding and life experience with energy. Current utility companies standardize data visualization formats for all customers, regardless of their literacy level. My aim for this dissertation is to evaluate how data visualization mediums (2D chart types and virtual reality visual aids) aid residents when reading, working with, analyzing, and arguing energy consumption data of household appliance pairs. The data visualization chart types explored include the area, bar, and circular column charts. The visual aids displayed in the virtual environment explored include color coding, electricity flow, and the power meter. The energy data of the household appliances is embedded within the visual aids without displaying energy metrics. The household appliances include lighting (LED vs incandescent bulb), cooking (air fryer and stove), and heating appliances (heat pump and space heater). The participants included 32 graduate students from Virginia Tech engineering programs. Results from the study showed that some participants had a hard time interpreting axis unit metrics energy such as watts, watt*minutes, and kWhs in all three 2D chart types. If participants could not read and work with the units on charts, their ability to analyze and argue about the energy data was diminished quickly. In addition, when participants were interacting with the visual aids, researchers discovered that the power meter was the easiest to convey because it provided participants with a way to qualitatively and quantitatively answer the questions presented by the questionnaire. This dissertation provides insights for researchers, utility companies, and policymakers to move away from standardized data visualizations and utilize alternative visuals for reading, working with, analyzing, and arguing residential energy consumption data. Researchers can utilize the dissertation insights to explore other data visualization mediums that have the potential to convey energy insights. Utility companies can begin implementing these alternative data visualizations in pilot programs to test their effectiveness with the public. And lastly, policymakers can enforce utility companies to prioritize customer literacy levels when administering utility bills. / Doctor of Philosophy / Data visualization has the power to tell a wonderful, meaningful, and thoughtful story when created with the end user in mind. The same thing can be said about visualizations on utility bills when tailored to a resident's energy, graphical, and data literacy level. A residents' literacy level results from their life experiences and circumstances dealing with energy data. Currently, data visualizations are standardized by utilizing companies, meaning that all individuals receive the same energy data visualization no matter their literacy level. My aim for this dissertation is to evaluate which data visualization chart types and VR visual aids enable reading, working with, analyzing, and arguing energy consumption data of household appliance pairs for residents. The data visualization chart types explored include the area, bar, and circular column charts. The visual aids explored include color coding, electricity flow, and the power meter. The household appliances include lighting (LED vs incandescent bulb), cooking (air fryer and stove), and heating appliances (heat pump and space heater). The participants included 32 graduate students from Virginia Tech engineering programs. Results from the study showed that some participants had difficulty reading and working with energy metrics on all three 2D chart types. If participants did not understand the units when reading and working with the charts their ability to analyze and argue the energy data was insufficient. In addition, when participants were interacting with the visual aids, researchers discovered that the power meter was the easiest to convey because it provided participants with a way to qualitatively and quantitatively answer the questions presented by the questionnaire. This dissertation provides insights for researchers, utility companies, and policymakers to move away from standardized data visualizations and utilize alternatives that enable reading, working with, analyzing, and arguing residential energy consumption data.

The stupendous growth in wireless and mobile devices in the recent years has prompted researchers to look at innovative approaches that enable effective use of the available resources. In this thesis, we propose a medium access control (MAC) protocol, referred to as EM-MAC, that enables wireless devices with multi-channel access capabilities while minimizing energy consumption. EM-MAC relies on iMAC's efficient channel selection mechanism to resolve the medium contention on the common control channel, and to select the best available data channel for data communication. Our protocol saves energy by allowing devices that have not gained access to the medium to switch to doze mode until the channel becomes idle again. The pair of devices that gains access to the data channel reserves and uses the channel until the end of the reservation period. At the end of each reservation period, devices belonging to a given data channel contend again for the medium, and only the pair of devices that wins access to the medium is allowed to communicate on the channel while all other devices switch to doze mode. Using simulations, we show that EM-MAC yields substantial energy savings when compared with iMAC. / Graduation date: 2012

In this exploration of the human battery interface, the way in which battery information and notifications effect interaction are analyzed through two small scale studies and a design proposal which is then user tested. With the first study, an attempt is made to gauge user’s feelings toward the current battery information display on their smartphones through a brief online questionnaire. Participants who were selected for further study installed battery monitoring software on their devices and shared the resulting data. This data was then analyzed and some usage patterns were extrapolated. After surveying current market solutions and research in the field, design opportunities were explored and a final design proposal was created and tested with possibilities for further applications being discussed.