Conference Papers

Peer influence and homophily in the diffusion of the iphone 3G in a very large social network

Godinho De Matos M., Ferreira P.A., Krackhardt D.

Proceedings - 2012 ASE/IEEE International Conference on Privacy, Security, Risk and Trust and 2012 ASE/IEEE International Conference on Social Computing, SocialCom/PASSAT 2012

2012

Abstract:

This paper studies the effects of peer influence and homophily on the diffusion of the iPhone 3G across a number of communities sampled from a large dataset from a major European Mobile carrier in one country. We use Stochastic Actor Based Models to capture the co-evolution of the social network as well as the dynamics of adoption. This helps to separate the roles of homophily and peer influence in the process of diffusion. We provide evidence that the propensity of a subscriber to adopt, when she is called upon to make a decision about whether she should adopt, increases with the number of friends that have already adopted. A one standard deviation increase above the mean in the number of friends that had already adopted increases the likelihood odds of adoption relative to no adoption by a factor of 2.8. The effect of peer influence is robust across a number of different specifications. The results for the effect of homophily are less clear. While, on average, we find a positive significant effect of adoption on tie formation, in many communities this effect is significant and negative and in others there is no effect at all.

PerCCS: Person-count from carbon dioxide using sparse non-negative matrix factorization

Basu C., Koehler C., Das K., Dey A.K.

UbiComp 2015 - Proceedings of the 2015 ACM International Joint Conference on Pervasive and Ubiquitous Computing

2015

Abstract:

Occupancy count in rooms is valuable for applications such as room utilization, opportunistic meeting support, and efficient heating-cooling operations. Few buildings, however, have the means of knowing occupancy beyond simple binary presence-absence. In this paper we present the PerCCS algorithm that explores the possibility of estimating person count from CO2 sensors already integrated in everyday room air-conditioning infrastructure. PerCSS uses task-driven Sparse Non-negative Matrix Factorization (SNMF) to learn a nonnegative low-dimensional representation of the CO2 data in the preprocessing stage. This denoised CO2 acts as the predictor variable for estimating occupancy count using Ensemble Least Square Regression. We tested the algorithm to estimate 15 minutes average occupancy count from a classroom of capacity 42 and compared its performance against existing methods from the literature. PerCSS estimates occupancy with a normalized mean squared error (NMSE) of 0.075 and outperformed our comparative methods in predicting occupancy count with 91 % and 15 % for exact occupancy estimation, when the room was unoccupied and occupied respectively, whereas the competing methods failed mostly.

Performance of data services in cellular networks sharing spectrum with a single rotating radar

Saruthirathanaworakun R., Peha J.M., Correia L.M.

2012 IEEE International Symposium on a World of Wireless, Mobile and Multimedia Networks, WoWMoM 2012 - Digital Proceedings

2012

Abstract:

This paper considers opportunistic gray-space primary-secondary spectrum sharing when the primary is a rotating radar. We assume that a secondary device is allowed to transmit when its interference does not exceed the radar’s tolerable level, probably because the radar’s directional antenna is pointing elsewhere, in contrast to current approaches that prohibit secondary transmissions if radar signals are detected at any time. The secondary system is a cellular system using the shared spectrum in some but not all of its cells; this may occur when the cellular system needs the shared spectrum to supplement its dedicated spectrum, or for a broadband hotspot service. It is shown that, even fairly close to the radar, extensive secondary transmissions are possible, although subject to interruptions as the radar rotates. For example, with 20% of the cells transmitting in the shared spectrum, on average the cellular system can achieve a data rate close to the one obtained in dedicated spectrum, even at less than 9% of the distance that secondary transmissions will not cause harmful interference in the radar’s main beam. By evaluating quality of service, it is shown that spectrum shared with radar is attractive for applications that generate much of the traffic on the Internet, including video streaming, peer-to-peer file sharing, downloads of large files, and web browsing, but not for an application sensitive to interruptions, like VoIP.

Permission-based programming languages (NIER track)

Aldrich J., Garcia R., Hahnenberg M., Mohr M., Naden K., Saini D., Stork S., Sunshine J., Tanter E., Wolff R.

Proceedings - International Conference on Software Engineering

2011

Abstract:

Linear permissions have been proposed as a lightweight way to specify how an object may be aliased, and whether those aliases allow mutation. Prior work has demonstrated the value of permissions for addressing many software engineering concerns, including information hiding, protocol checking, concurrency, security, and memory management. We propose the concept of a permission-based programming language – a language whose object model, type system, and runtime are all co-designed with permissions in mind. This approach supports an object model in which the structure of an object can change over time, a type system that tracks changing structure in addition to addressing the other concerns above, and a runtime system that can dynamically check permission assertions and leverage permissions to parallelize code. We sketch the design of the permission-based programming language Plaid, and argue that the approach may provide significant software engineering benefits.

Piecewise planar and compact floorplan reconstruction from images

Cabral R., Furukawa Y.

Proceedings of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition

2014

Abstract:

This paper presents a system to reconstruct piecewise planar and compact floorplans from images, which are then converted to high quality texture-mapped models for free- viewpoint visualization. There are two main challenges in image-based floorplan reconstruction. The first is the lack of 3D information that can be extracted from images by Structure from Motion and Multi-View Stereo, as indoor scenes abound with non-diffuse and homogeneous surfaces plus clutter. The second challenge is the need of a sophisticated regularization technique that enforces piecewise planarity, to suppress clutter and yield high quality texture mapped models. Our technical contributions are twofold. First, we propose a novel structure classification technique to classify each pixel to three regions (floor, ceiling, and wall), which provide 3D cues even from a single image. Second, we cast floorplan reconstruction as a shortest path problem on a specially crafted graph, which enables us to enforce piecewise planarity. Besides producing compact piecewise planar models, this formulation allows us to directly control the number of vertices (i.e., density) of the output mesh. We evaluate our system on real indoor scenes, and show that our texture mapped mesh models provide compelling free-viewpoint visualization experiences, when compared against the state-of-the-art and ground truth.

Plaid: A permission-based programming language

Aldrich J., Bocchino R., Garcia R., Hahnenberg M., Mohr M., Naden K., Saini D., Stork S., Sunshine J., Tanter E., Wolff R.

SPLASH'11 Compilation - Proceedings of OOPSLA'11, Onward! 2011, GPCE'11, DLS'11, and SPLASH'11 Companion

2011

Abstract:

Access permissions (permissions for short) are a lightweight way to specify how an object may be aliased and whether aliases allow mutation. Prior work has demonstrated the value of permissions for addressing many software engineering concerns, including information hiding, protocol checking, concurrency, security, and memory management. We propose a permission-based programming language: that is, a language whose object model, type system, and runtime are all co-designed with permissions in mind. The key elements of such a language are (1) an object model in which the structure of an object can change over time; (2) a type system that tracks changing structure in addition to addressing concerns such as those listed above; and (3) a runtime system that dynamically checks permission assertions and leverages permissions to parallelize code. We sketch the design of the permission-based programming language Plaid and argue that the approach promises significant software engineering benefits.

Playdough to Roombots: Towards a Novel Tangible User Interface for Self-reconfigurable Modular Robots

Mutlu M., Hauser S., Bernardino A., Ijspeert A.

2018 IEEE International Conference on Robotics and Automation (ICRA)

2018

Abstract:

One of the main strengths of self-reconfigurable modular robots (SRMR) is their ability to shape-shift and dynamically change their morphology. In the case of our SRMR system “Roombots”, these shapes can be quite arbitrary for a great variety of tasks while the major utility is envisioned to be self-reconfigurable furniture. As such, the ideas and inspirations from users quickly need to be translated into the final Roombots shape. This involves a multitude of separate processes and – most importantly – requires an intuitive user interface. Our current approach led to the development of a tangible user interface (TUI) which involves 3D-scanning of a shape formed by modeling clay and the necessary steps to prepare the digitized model to be formed by Roombots. The system is able to generate a solution in less than two minutes for our target use as demonstrated with various examples.

Playing Games in the Dark: An Approach for Cross-Modality Transfer in Reinforcement Learning

Silva, R.; Vasco, M; Melo, Francisco S.; Paiva, A.; Veloso, M.

AAMAS2020

2020

Abstract:

In this work we explore the use of latent representations obtained from multiple input sensory modalities (such as images or sounds) in allowing an agent to learn and exploit policies over different subsets of input modalities. We propose a three-stage architecture that allows a reinforcement learning agent trained over a given sensory modality, to execute its task on a different sensory modality-for example, learning a visual policy over image inputs, and then execute such policy when only sound inputs are available. We show that the generalized policies achieve better out-of-the-box performance when compared to different baselines. Moreover, we show this holds in different OpenAI gym and video game environments, even when using different multimodal generative models and reinforcement learning algorithms.

PMU placement to ensure observable frequency and voltage dynamics: A structured system approach

Pequito S., Liu Q., Kar S., Ilic M.D.

Proceedings of the Annual Hawaii International Conference on System Sciences

2013

Abstract:

The incorporation of sophisticated sensing technology, notably the phasor measurement units (PMUs), offers tremendous opportunities toward real-time dynamic state monitoring in the smart grid. With a view to effectively exploiting the potentials of these advanced and non-conventional sensing resources, this paper is concerned with the design of PMU placement and sampling methodologies that optimize the state estimation performance in the face of infrastructure and communication limitations. Specifically, on the qualitative front, the paper addresses the minimal placement requirement (measured in terms of the minimal number of sensing units to be deployed) that guarantees dynamic system observability, and explicitly characterizes the desired placement configuration(s) that ensure such observability. Simulation studies performed on the IEEE 5-bus system (with 37 dynamical state components) demonstrate the effectiveness of the proposed approach.