Category Archives: conference

Thoughts on ENERGY 2013 conference


I just finished attending the ENERGY 2013 conference in Lisbon. The conference was a part of InfoSys 2013, which consists of several smaller conference all bundled together. Each day had one keynote and on panel discussion drawn from all the different conferences/tracks,  making for an interesting, and eclectic experience. There were perhaps 30 attendees for the ENERGY subconference, so I got to know several of the presenters.

I was presenting our paper on lessons learned from designing energy feedback visualizations for the Kukui Cup. Our three lessons about feedback visualizations is that they should be actionable, that domain knowledge must go hand in hand with energy feedback systems, and that this feedback must be “sticky” to lead to changes in behaviors and attitudes. While I was probably the only attendee focused on feedback visualizations and behavior, I got some interesting feedback from other energy attendees, such as finding additional ways to connect to undergraduates (e.g., beer :))

Below are my notes on some of the presentations I found noteworthy. So nice to be at a conference with open access to the proceedings so I can link to them directly!

Energy Aware Scheduling

Kanad Ghose presented on Dynamic Classification of Repetitive Jobs In Linux For Energy-Aware Scheduling: A Feasibility Study. 2.8% of electricity in the US is used by datacenters, and their research is on trying to find ways to reduce energy use in the datacenter environment. The basic idea is that some jobs are CPU-bound and others are I/O bound, so on a server with multiple CPUs, some CPUs can downshifted in voltage and frequency for I/O bound tasks (which spend most of their time waiting for I/O requests) with a consequent savings in energy. The other CPUs are kept at the highest performance level for the CPU-bound jobs. Each type of job (identified by the executable image) is classified, and jobs are scheduled by the kernel on the properly tuned CPU. Interesting work, and they are seeing about 5-10% reductions in energy use with small increases in latency. In the future they foresee servers in the data center communicating data about their loads (and predicted loads) to the HVAC system to further reduce energy use by preventing overcooling.

Voltage Sensors for Smart Grids

Chris Yakymyshyn from FieldMetrics presented on his work on Sensors for Smart Grids, which focused on the complexities of designing voltage and current sensors for the medium-voltage environment that are highly accurate. Utilities are typically required to provide electrical power within certain bounds of voltage and frequency. In the past, utilities had usually just targeted the center of the range for safety, but they have now realized that by reducing the provided voltage to the bottom of the regulated range they can save huge amounts of energy, avoiding the need to construct additional power plants! However, to skirt the edge of the regulated range, utilities need to actually measure the voltage they are providing so they can avoid fines for being outside the range.

One neat thing is that the sensors they have designed work optically,  taking advantage of the Pockels effect whereby an electric field changes the index of refraction of certain crystals. Their sensor produces polarized light, which is guided through multiple crystals, and a sensor at the other end measures the angle by which the polarization light has been rotated.

The results from their field trials with BC Hydro are equally interesting. One major application by BC Hydro is detecting energy theft. To detect theft, a power sensor is installed on the medium-voltage transmission line before a group of customers, and then after the group. Combined with smart meter data from the customers, the utility can determine how much power should have been drawn off the medium-voltage line compared to what the smart meters reported. In one neighborhood, approximately 27% of the delivered electricity was being stolen, and the majority of that was coming from (illegal) marijuana grow operations! This leads me to ponder how much energy we could save if growing marijuana was legal, which would allow for more outdoor growing, or at least energy audits of facilities. 🙂

Energy Storage & Vehicle-to-Grid (V2G)

Mark Apperley from the University of Waikato, New Zealand brought a wonderful discussion on energy storage and specifically vehicle-to-grid (V2G) storage. One of the conference panel discussions focused on energy storage. The discussion was quite wide-ranging, and I found the following points interesting

  • Mark pointed out that we all have a storage system in our homes for a different resource: toilets. Toilets store water, dispensing it at 140 l/m, but refill at 30 l/m. The water storage provides two benefits to water-providing utility: it smooths out the load generated when people flush, and it also provides an “infrastructure improvement” since the water pipe coming to homes is not sized to provide water at the rate needed to flush. Electricity storage would also provide these same two qualities. For example, as electric vehicles become more widely used, the distribution lines to neighborhoods may become overburdened as adding an electric vehicle roughly doubles the electricity use of a home. In a neighborhood with many EVs, some vehicles may discharge to provide their neighbors with power which the utility is not able to provide with the existing distribution lines.
  • In talking about the growth of renewable energy, Chris Yakymyshyn pointed out that fossil fuel power plants need to run a certain percentage of the time in order to make a profit. If they are only being used a small percentage of the time to support intermittent renewable energy sources, they will shut down and go bankrupt.
  • I shared point made by Mark Duda, a founder of residential-solar installing company RevoluSun in Hawaii. He pointed out that since electricity prices are very high in Hawaii, PV is quite cost-effective for many homeowners, some of whom also install a battery storage system so they can go completely off the grid. Hawaiian Electric (like all utilities) has large fixed costs (power plants are expensive!) that it has to pay regardless of how much electricity they actually generate. Thus as more people are able to switch to solar, Hawaiian Electric will have to spread the fixed costs over fewer customers, leading to higher rates. This makes solar cost effective for even more homeowners, who then disconnect from the grid, which could lead to a spiral when the utility can no longer afford to pay its fixed costs.

Mark also gave a keynote talk on his research into V2G in New Zealand. The concept of using electric vehicles as a storage system for the grid is not new, as it was first suggested by Kempton and Letendre in 1997. Two important issues for V2G are that the electric vehicles need to be plugged in to be a resource for the grid, and that the decision on whether to charge from the grid or discharge to the grid requires knowledge of the planned usage of the vehicle (e.g., when will the owner be driving home?).

The promise of V2G is that vehicles are only used a small portion of the time. In NZ, vehicles are estimated to be used only 4% of the time, providing a lot of potential time for grid backup. Mark has created a fine-grained simulation of electric vehicle use for grid storage in NZ, with a 1 minute time scale, individual vehicle simulation, and real utility load data (we can only dream of this level of data in Hawaii!). The simulation also takes into account the gradual adoption of electric vehicles.

Based on the simulation results, with 400,000 EVs, V2G reduced peak energy generation requirements, and flattens out the demand curve. Unfortunately, it did not actually reduce the height of the peak load: while EVs can be helpful for storage, they also increase demand for electricity for their use as transportation. As an amusing aside, Mark said that one of his student’s had computed that if all the laptops in NZ could be linked to the grid, they would be able to handle the national load for a few minutes 🙂

It would be great to see a simulation of how V2G would work (or not) for Hawaii, but it would require a lot of data that is not available outside of Hawaiian Electric.

Mahalo to all the participants and organizers of ENERGY 2013!

Meaningful Play 2012

For the past 4 days I have been attending the Meaningful Play 2012 conference. MP is an interesting mix of game design and game analysis, with a heavy focus on serious games, games for learning, games for impact, or whatever you want to call them. The 2012 proceedings are available online, but surprisingly not linked off the main page. I was there presenting our paper Beyond kWh: Myths and fixes for energy competition game design, which explains the counter-intuitive energy use from the 2011 UH Kukui Cup, and our investigation into the methodology of energy competitions in general. I also demoed the Kukui Cup at the MP game demo session, and there were a lot of good games there.

The following are some quick thoughts on the conference from my perspective, with special emphasis on things relevant to our work on the Kukui Cup and serious games for sustainability.

Donald Brinkman from from Microsoft Research gave the opening keynote. He’s one of the leaders of the Just Press Play project, which is a game experience for game design students at RIT intended to reduce student attrition and increase interaction between students. There are many parallels between Just Press Play and the Kukui Cup: players can earn achievements for certain actions, there are real world events that players can get credit for attending. They originally handed out 25 digit attendance codes on cards, but players were (understandably) not pleased about typing in long codes to get their achievements. Their latest iteration of the system gives a QR code to each player, and admins scan the codes using a smartphone app in order to award achievements. This is a nice solution to the problem, though I wonder how many students will forget or lose their QR code. I have a feeling that would be a problem at UHM, where many students seem to wander the area around the residence halls with just their ID card and keycard. I’m also curious to see how the heavy emphasis on badges, with no points or leaderboard will play out. Once you have many badges, I worry it will make badges somewhat meaningless (see Achievement Unlocked 2).

One aspect of the Kukui Cup that we have sometimes bemoaned is the fact that it is optional, and so only a portion of the 1000+ residents in Hale Aloha participate. However, something that came up many times during the conference is the idea that being optional is good. In fact, some presenters believe that mandatory play is not really play at all.

There was a presentation by Steven Dodds, Carrie Heeter, and Andy Simon about civic gaming in San Jose that really piqued my interest. The team presenting have run “budget games” where small groups sit at a table and have to make decisions about what city projects to fund, which to cut, and how to raise revenue. The results of the games have then been largely incorporated into the mayor’s budget request! The most fun workshop I attended was titled “Pervasive and Environmental Game Design” by Jeff Watson from USC. The topic was really about games for action: instead of simulating the world or telling players how to change it, make the game actually be about taking action. The audience was broken up into small teams, and given the objective of creating a working game prototype that addressed some issue regarding the MP conference itself. Our team designed a game intended to increase the networking at the conference, which we called Network Bingo, where each player has to collect business cards from other attendees, and try to fill up a bingo card with organizational roles across the top (student, professor, designer, etc) and application area going down (health, sustainability, etc). We didn’t quite get to the point where we had a playable prototype (only one team did), but the experience was awesome and opened me up to new possibilities in this space. I’d really like to create a analog game that lets the players explore Hawaii’s energy and sustainability issues using these techniques.

One thing that struck me after seeing all the awesome games and research going on at the conference is how much we could improve the learning potential of the Kukui Cup by making it more “procedural rhetoric” (Ian Bogost’s term). While we do have some activities like the Energy Scavenger Hunt where we teach players things implicitly as part of the game play, still too much content relies on watching a video and answering a question, which is only a game by from a very charitable viewpoint. This orientation was necessary to meet our requirements, since sustainability is a enormous topic and given our available resources making a game for each subtopic would have been completely infeasible. But as the Kukui Cup matures, we need to start making more and more of the experience gamelike and less like traditional teaching.

Meaningful Play was a blast (even if it rained a lot!) and I look forward to the next one in 2014!

Thoughts on HICSS 44 (2011)

I just got back from the Hawaii International Conference on System Sciences, aka HICSS. This conference has been running for 44 years. General information about this year’s HICSS can be found here, and the proceedings will eventually be here.

This was my first HICSS, which is kinda strange seeing how long I have been in Hawai`i. It was held this year at the Grand Hyatt Kauai, which is pretty luxurious. I guess the idea is to hold it at resort that will be a draw for participants, and provide enough amenities that attendees don’t feel the need to wander off.

The first thing that struck me about HICSS is the incredible diversity of sessions going on. The conference is organized in as a bunch of tracks (high-level topics), which are then broken into about 60 minitracks. The minitracks can last a whole day (4 sessions) or be as short as a single session.

The result is a huge smorgasbord of papers. Each day, there are 15 parallel tracks, ranging all over the place: education, social networks, cyber security, location-based marketing, power systems, and many more. This can be good if you want to check out a diverse set of presentations, but to me it makes HICSS feel more like a conference of mini-conferences than a unified whole. This is quite different from a conference like Ubicomp, which is vociferously single-track so that every attendee can attend every session if they want to. Naturally, Ubicomp accepts far fewer papers than HICSS.

The minitrack I was attending (Information Systems and Decision Technologies for Sustainable Development) didn’t start until the second day, so on the first day I just went to sessions that looked interesting. Just deciding which sessions to attend is quite a task: 15 rooms * 4 sessions a day = 60 paper titles to look at!

I started with the Future Electric Power Systems (smart grid, more or less) minitrack. This minitrack was located in a standalone building at the Hyatt that is used as a nightclub. So the attendee chairs were set up in a sunken dance floor, and the presentation slides were shown on one large TV embedded in the wall, as well as 16 smaller TVs distributed around the ceiling (like one might find in a sports bar). This was kinda bizarre, but amusing.

The power systems minitrack has been running for 15 years, so the attendees seemed quite familiar with each other, and had their conference process down pat. The papers I saw were interesting, though more traditionally smart-grid-oriented compared to our Kukui Cup work. Unfortunately, the proceedings (which will be freely available) are not yet online, so I cannot link directly to papers.

  • A case study on the expected impact of PHEV vehicles on electricity consumption, using a new community in South Korea (A Case Study on the Grid Impact of PHEVs to Sample Distribution Power System by Dong Joo Kang and Sunju Park)
  • An algorithm for detecting “load pockets”, which are areas on the grid that are constrained by transmission such that generation facilities could raise their prices and electricity users would have no option but to pay the higher prices (Clustering of Power System Data and its use in Load Pocket Identification by Katherine Rogers and Thomas Overbye).
  • An analysis of locational marginal carbon intensity of generation (how much additional carbon will be emitted by increasing demand by 1 kWh in a particular location at a particular time) on the eastern part of the US. The results are somewhat surprising, in that areas that are heavy coal users might actually have lower marginal carbon intensity because if they had additional demand they would import power from generation facilities with lower carbon intensity. The presenter related the marginal intensity to Renewable Portfolio Standards, which provide subsidies for production of renewable energy. Currently subsidies are independent of carbon intensity, but the authors argue that they should be higher (pay more for renewable energy) in places where the marginal carbon intensity is high, and lower where marginal intensity is low. This would encourage the buildout of renewable generation in places where it would reduce carbon emissions the most (Locational Carbon Footprint and Renewable Portfolio Policies: A Theory and its Implications for the Eastern Interconnection of the US by Aleksandr Rudkevich, Pablo A. Ruiz and Rebecca C. Carroll).
  • An investigation into what is really happening in loads, starting with hot water heaters. The presenter argued that there has been a lot of research into the dynamics of generation, but very little in the dynamics of loads, which will be critical for any type of demand response program. In the ensuing discussion, I learned a new term: demand subscription. This is the idea that rather than being metered for use, customers subscribe to a certain amount of electricity (not sure if it is measured as power, energy, or both) and then it is up to the customer to figure out how to live within that subscription. So the utility would only communicate with a smart meter, not reaching beyond the meter to smart appliances.

I also had time to attend some talks in the social networking track by members of LILT (my former research group): Dan Suthers, Kar-Hai Chu, and Devan Rosen. I was familiar with some of the outlines of the Traces work, but it was good to see it discussed in a public forum.

The minitrack I presented in was called Information Systems for Sustainable Development. I presented our paper describing the design of the Kukui Cup. It seemed well received, with most of the questions revolving around how to get students involved and how to keep them aware after the competition in order to sustain behavior changes. Eric Paulos suggested we should provide Kill-A-Watt meters to some residents in May 2012 before they move out of the first-year dorms, and then follow up with them on whether and how they used them in their next living situation.

Two other presentations in our track that I found interesting:

  • Hendrik Hilpert, a PhD student from Göttingen University presented work on computing products’ carbon footprints automatically using vehicle mass airflow data (obtained via OBD2) fused with GPS data. This combination allows one to compute how much carbon is being emitted, while the GPS data allows the carbon to be allocated to different products that might be on the same delivery vehicle as it makes a series of stops. They even cited my older literature review in their paper, würd! (Real-Time Data Collection for Product Carbon Footprints in Transportation Processes Based on OBD2 and Smartphones, by Hendrik Hilpert, Lars Thoroe and Matthias Schumann).
  • Eric Paulos, assistant professor at CMU presented work on Citizen Energy. Citizen Energy is the idea of changing people from just being energy consumers into more active participants in the generation and use of energy. They have made a bunch of cool devices, like a Seasonal Energy Lamp. The lamp is connected both to grid power and to solar and wind turbines, and it changes the color of the emitted light depending on the source (orange for solar, blue for wind, etc), making people more aware of where their energy is coming from. These design experiments seem really complementary to the Kukui Cup, possibly providing additional ways for participants to become more energy literate. (Citizen Energy: Towards Populist Interactive Micro-Energy Production by Eric Paulos and James Pierce).

Unfortunately, our minitrack had fairly low attendance (perhaps 8 attendees at peak, of whom half were presenting in the minitrack), so I don’t know how it will fare next year. All in all, it was a worthwhile experience, but was a bit of a comedown after BECC 2010.

Notes from SmartGridComm 2010

Last week I attended the first Smart Grid Communications conference. I was presenting our paper on WattDepot. The presentation went well and there were several questions afterward. One point that I got several questions about was our requirement to support rapid data collection (sub-minute), since that is much faster than most commercial meters support. In retrospect, I should have emphasized our application domain (the Kukui Cup) more in the presentation, which might have helped to explain that requirement.

The following are some of my notes from the conference:

  • There were 102 papers accepted at the conference (40% acceptance rate), and 441 registrations. The mix was roughly 44% academic, 31% industry, 20% R&D, and 5% government.
  • The conference was held at NIST, and throughout the building were NIST clocks that presumably were very accurate. 🙂
  • There is a Smart Grid Consumer Collective, which sounds like an organization we should keep an eye on.
  • There are apparently standard power network topologies that can be used for analysis and research, such as the IEEE 300 bus power flow test case.
  • Some power industry slang I was not aware of: “big wire” relating to electricity distribution, “little wire” relating to communication networks. As in “the Smart Grid is all about the little wire people working with the big wire people.”
  • Georgios Kalogridis presented work on “Privacy for Smart Meters: Towards Undetectable Appliance Load Signatures”. The basic idea being that if the utility has fine-grained data about energy usage, they can determine a lot about what the consumers are doing. Kalogridis et. al. propose a system where a rechargeable battery is located in the home, and can be used to mask the signatures of energy use by charging and discharging at appropriate times. They cite this interesting paper by Elias Quinn that lays out all the potential privacy issues related to fine-grained energy usage data.
  • Came across a reference to Stanford’s PowerNet project, which aims to measure the “energy consumption of enterprise-style computing infrastructures”. Looks cool, paper here.
  • Hironori Nakanishi from the Japanese government reported on the Japanese perspective on the smart grid. Apparently Japanese utilities were not that eager to pursue smart grid upgrades because on average a Japanese consumer has 16 min/year of power outage, compared to the US average of 162 min/year. However, the Japanese government set the target of 25% CO2 reduction by 2020, which will require 28 GW of new solar power.
  • I also had not heard about the Hawaii-Okinawa partnership on clean energy.
  • One of the reasons that demand-side management is being pursued is for “peak shaving” by shifting some appliance loads to off-peak periods. Unfortunately, if all the smart appliances decide to shift their loads to the start of the off-peak pricing period, then you get a rebound peak. This seems like a challenging problem, barring real-time pricing that takes the rebound peak into account.
  • Jay Taneja presented work from UCB on shifting appliance loads to make maximal use of fluctuating renewable energy.The idea is that certain thermostatically-controlled loads like a refrigerator store electrical energy as thermal energy, so they can be scheduled based on the availability of renewable energy (in their study, wind energy). So if there is excess wind energy available, the fridge compressor could run more frequently, and vice versa. Bringing data about grid renewable energy production is something we have been thinking about from the consumer human interface perspective (the carbon “traffic light” concept), but they are working on making actual appliances sensitive to renewable production. Very cool.
  • In total, I gave out 11 business cards, and 2 REIS brochures.

Next year the conference is in Brussels. Paper deadline is April 4, 2011.

Future publication venues

Update March 5, 2010: now maintained as a wiki page rather than a blog post

Updated Feb 2, 2010: added IEEE upcoming journals and IEEE Sensors conference.

So I’ve been thinking lately about where I might publish my research on WattDepot, and later on the UH dorm energy challenge. Here’s what I have come up with so far.


  • IEEE Smart Grid Conference. The deadline for papers is May 1, with the conference happening Oct 4-6 in Maryland. Philip has suggested this might be a good place for a paper on WattDepot, and I agree. The maximum page length is 6 pages.
  • Behavior, Energy, Climate Change 2010. Philip attended BECC 2009 and it seems like an ideal conference for the dorm energy competition results. The call for abstracts (presentations & posters) goes out in March, with a mid-May deadline to submit abstracts. The conference is November 14-17 in Sacramento. There is no paper required for the presentation, just slides, so we could potentially present some actual results in the presentation (which wouldn’t be available in May when the abstract is submitted).
  • Hawaii International Conference on System Sciences 44. This is happening on Kauai January 4-7 2011. The deadline for papers is June 15. The Jennifer Mankoff’s group has had a series of papers about StepGreen and related work at HICSS so this seems like a good venue, and the travel will be much easier. 🙂
  • CHI 2011. Apparently this is happening May 7-12 in Vancouver (BC I assume?). There have been a variety of papers on supporting green/sustainable behavior in CHI before, and the CHI community is a large and vibrant one.
  • Ubicomp 2010. There was plenty of sustainability work at Ubicomp 2008 (including a workshop I attended), so this is a possible venue. However, the submission deadlines are rather soon (March for papers) so it’s probably more realistic for 2011.
  • Pervasive 2011. This is similar to Ubicomp, but happens in May in Europe. Submission deadline is mid-October.
  • IEEE Sensors 2010. May 4 is the abstract submission deadline, with the conferencing happening November 1-4 at the Hilton Waikaloa. Maximum paper length is 4 pages. This is perhaps less relevant than the IEEE Smart Grid conference, but still worthy of consideration.


  • International Journal of Sustainability in Higher Education. This is where the Oberlin dorm energy contest paper was published, so it seems an obvious choice. Not the broadest appeal though.
  • Environment & Behavior.
  • IEEE Transactions on Smart Grid. Journal to be launched soon.
  • IEEE Transactions on Sustainable Energy. Another journal to be launched soon. The smart grid one looks more relevant, this looks to be focused on energy generation from renewables.

I’m sure more will come up as I read more, but this is a good starter list.

Building WattDepot REST API

After getting the simple ping server working with Restlet, last week I turned my attention to the WattDepot REST API, since the API drives the functionality that I will be implementing. Staring at the blank wiki page, I turned to the O’Reilly book RESTful Web Services (link to book content via Safari Books Online for UHM folks). The book is an excellent introduction into why REST makese sense for web services, and goes step by step through the process of designing web services using their Resource Oriented Architecture. So I spent a lot of time reading the book to see examples of how to turn requirements into a ROA API.

There is now a REST API wiki page for WattDepot, but it’s mostly requirements at this point. This week I plan to crank out a first draft of the API, so I can start implementing it ASAP.

There are now 4 weeks left before the semester starts. I’d like to have data persistence, a client that can retrieve Obvius meter data and send to WattDepot, and Google gadget visualization working by then, so my work is cut out for me.

Plans from last week:

  • Read through sensorbase REST API
    • done
  • Start work on WattDepot REST API
    • done
  • Read up on Google Visualization data source library
    • not done
  • Write down initial thoughts on research questions
    • not done

Other accomplishments from last week:

  • Read through first 6 chapters of RESTful Web Services
  • Attended the TechHui conference. There was a lot of good info about renewable energy development, and other tech goodness.
  • Found one more small bug in Hackystat build files, now they should really really be stable 🙂
  • Attended UH SecondLife gettogether, complete with live DJ and dancefloor. It was fun, but I still don’t see myself spending any significant time in SL.

Pointers to work products:

Plans for this week:

  • Finish first draft of WattDepot REST API
  • Follow up on some contacts from Tech Hui conference
  • Read up on Google Visualization data source library

Cool links:

  • Damon Hart-Davis (creator of the site I mentioned last week) has pointed out that Ecotricity (a UK utility) has similar carbon intensity data on their web page. This is precident for utilities sharing this kind of data.
  • Blue Mars is a new massively multi-player online virtual environment like Second Life, being developed in Honolulu. The graphics are far superior to SL, and the business model is interesting in that they are specifically designing it around making it easy for content developers to make a living creating content for Blue Mars. They are also hoping to attract indie game developers to rent out a city block of space where they can create their games with autonomy and make money from it. They are taking beta applications for the client now, but if you are a developer you can get the dev kit right now at their developer website.

Lessons learned from Ubicomp

These are meta-issues I learned from attending the conference, to remember for the next conference I attend.

  • Don’t leave the night the conference ends if possible. I didn’t know the daily schedule for Ubicomp until long after I had made my travel reservations. Turns out the conference schedule went past 6 PM, so I had to leave before the end of the conference to catch my flight. In future I’ll just plan to stay that extra night so I can be sure to attend the conference until the end, and not have to deal with my luggage the last day of the conference.
  • I think it’s time to update the canonical CSDL presentation template. I think the style and font choice seem somewhat dated now. While I don’t believe in presentations with fancy backgrounds and other fripperies, I think it could be updated. In a conference environment, it was quite helpful to see information in the header & footer of presentations: slide N of M, presenter name & organization.
  • If I had more time in South Korea, I would have visited the DMZ. However, while giving blood last week I learned that there are three different strains of malaria in the DMZ area, and if I had visited I would not have been allowed to give blood for 2 years!

Action items from Ubicomp

This is a list of specific things to follow up on from Ubicomp:

Ubicomp 2008 blogging, day 3: location aware applications

The most interesting part of day 3 for me was the session on location-aware applications. The first paper was The potential for location-aware power management from Robert Harle and Andy Hopper of the University of Cambridge. They analyze a set of highly-accurate location data from a commercial office to see what energy savings could be enabled by knowing where the user is located in the building. They found the potential for savings for devices that can be switched on and off quickly (like lights or waking a computer from sleep), but the problem is much harder for slower systems like HVAC. For the slow systems, only outside office hours and lunchtime could be predicted with the accuracy required to have rooms ready when the user returned.

The other big paper for me was Understanding mobility based on GPS data, which covered using GPS data to determine what transportation method was being used (sound familiar? 🙂 ) They found that just using velocity data from GPS doesn’t work well (< 50% accuracy). They follow the standard machine learning process: segmentation of the data, extracting features that are representative of those segments, and feeding that into a generative model. They had 70 people using their system for a year, which is a huge amount of GPS data. This is definitely a paper I need to fully understand.

I had to leave to catch my flight before the closing panel session finished, but what I heard was interesting. There was spirited debate on where ubiquitous computing was going, where the conference was going, complaints about the many related conferences (Pervasive, MobileCHI). Too bad I had to leave early.

Ubicomp 2009 is in Orlando FL. Not sure at this point if I’ll be going or not.

Ubicomp 2008 blogging, day 2: location sensing and more

[Getting back to blogging Ubicomp from my notes. Unfortunately ran out of time while the conference was going on]

Location sensing was the first session of the day, and this is one of the most developed areas in ubiquitous computing. The first talk was on using signals injected into the power wiring of a building to sense location. The idea being that you attach a transmitter to normal home power wiring to inject some signals (earlier work used 2 frequencies, this paper was using wideband) that can be sensed throughout the house. Then you can map out the received values for those signals throughout the house, and then later use that mapping to sense where a receiver is located. The second talk was on using CDMA signals (from carriers like Sprint in the US) to locate users based on the signal delay. Using GSM and WiFi signals are already well established, apparently, but all three require mapping the signal strength/delay in the space to be used for location.

The best paper award for the conference went to Pedestrian localisation for indoor environments. The goal of this system is to be able to track pedestrians indoors using no infrastructure, unlike ultrasonic systems that can be extremely accurate, but require expensive transducers every couple meters. The system uses a combination of pedestrian dead reckoning and robot localization techniques. A shoe-mounted inertial sensor can detect the users steps, but accelerometers have drift that eventually creates too much error. That drift is compensated for using the robot localization technique. A model of the building’s floor plan is created or derived from blueprints, and given the motion information from the inertial sensor, guesses can be made on where the user is located in the building. Since the user cannot walk through walls, as they walk further the system uses a particle filter to winnow down the set of possible locations. It’s neat work, though it does require an accurate map of the indoor environment.

Another interesting paper in a completely different area is Towards the automated social analysis of situated speech data. The authors use automated voice recorders that record everything the subjects say, but then throw away the raw audio data and keep only information about which subjects talk to each other, and some variables about their speech (pitch, number of conversational turns, etc). Using this data they can create an automated sociogram based on who spoke to who.

In the security and privacy track there was a talk about the privacy problems associated with the fine-grained sensors used for activity sensing in the home. The authors point out that one can snoop on the wireless data transmissions, and even through they are encrypted, one can infer which sensors are being activated based on time of day and standard usage patterns.

The conference day ended with a Town Hall session. This was a discussion about the administrative aspects of an ongoing conference: location of next year’s conference, whether to be sponsored by ACM, straw polls on whether to go all digital for the proceedings, etc. It was quite cool to see the internal aspects of the conference discussed in an open and somewhat democratic forum.