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Uncovering Hidden Structure through Parallel Problem Decomposition for the Set Basis Problem
Xue, Yexiang (Cornell University) | Ermon, Stefano (Stanford University) | Gomes, Carla (Cornell University) | Selman, Bart (Cornell University)
Exploiting parallelism is a key strategy for speeding up computation. However, on hard combinatorial problems, such a strategy has been surprisingly challenging due to the intricate variable interactions. In this paper we introduce a novel way in which parallelism can be used to exploit hidden structure of hard combinatorial problems, orthogonal to divide-and-conquer and portfolio approaches. We demonstrate the success of this approach on the minimal set basis problem, which has a wide range of applications e.g., in optimization, machine learning, and system security. We also show the effectiveness of our approach on a related application problem from materials discovery. In our approach, a large number of smaller sub-problems are identified and solved concurrently. We then aggregate the information from those solutions, and use this information to initialize the search of a global, complete solver. We show that this strategy leads to a significant speed-up over a sequential approach since the aggregated sub-problem solution information often provides key structural insights to the complete solver. Our approach also greatly outperforms state-of-the-art incomplete solvers in terms of solution quality. Our work opens up a novel angle for using parallelism to solve hard combinatorial problems.
Agents Vote for the Environment: Designing Energy-Efficient Architecture
Marcolino, Leandro Soriano (University of Southern California) | Gerber, David (University of Southern California) | Kolev, Boian (California State University, Dominguez Hills) | Price, Samori (California State University, Dominguez Hills) | Pantazis, Evangelos (University of Southern California) | Tian, Ye (University of Southern California) | Tambe, Milind (University of Southern California)
Saving energy is a major concern. Hence, it is fundamental to design and construct buildings that are energy-efficient. It is known that the early stage of architectural design has a significant impact on this matter. However, it is complex to create designs that are optimally energy efficient, and at the same time balance other essential criterias such as economics, space, and safety. One state-of-the art approach is to create parametric designs, and use a genetic algorithm to optimize across different objectives. We further improve this method, by aggregating the solutions of multiple agents. We evaluate diverse teams, composed by different agents; and uniform teams, composed by multiple copies of a single agent. We test our approach across three design cases of increasing complexity, and show that the diverse team provides a significantly larger percentage of optimal solutions than single agents.
NOTES2: Networks-of-Traces for Epidemic Spread Simulations
Liu, Sicong (Arizona State University) | Garg, Yash (Arizona State University) | Candan, K. Selcuk (Arizona State University) | Sapino, Maria Luisa (University of Torino) | Chowell-Puente, Gerardo (Arizona State University)
Decision making and intervention against infectious diseases require analysis of large volumes of data, including demographic data, contact networks, age-specific contact rates, mobility networks, and healthcare and control intervention data and models. In this paper, we present our Networks-Of-Traces for Epidemic Spread Simulations (NOTES2) model and system which aim at assisting experts and helping them explore existing simulation trace data sets. NOTES2 supports analysis and indexing of simulation data sets as well as parameter and feature analysis, including identification of unknown dependencies across the input parameters and output variables spanning the different layers of the observation and simulation data.
Game Theoretic Considerations for Optimizing Efficiency of Taxi Systems
Gan, Jiarui (Institute of Computing Technology Chinese Academy of Science) | An, Bo (Nanyang Technological University)
Taxi service is an indispensable part of public transport in modern cities. The taxi system is operated by a large number of self-controlled drivers lacking of centralized scheduling and control, which makes it inefficient, difficult to analyze and optimize. It is thus important to take into account taxi drivers' strategic behavior in order to optimize taxi systems' efficiency. This paper reviews existing taxi system researches for modeling taxi system dynamics, introduces the taxi system efficiency optimization problem, and presents a game theoretic approach for optimizing the efficiency of taxi systems. Challenges and open issues in the taxi system efficiency optimization problem are also discussed.
Privacy-Utility Trade-Off for Time-Series with Application to Smart-Meter Data
Erdogdu, Murat A. (Stanford University) | Fawaz, Nadia (Technicolor) | Montanari, Andrea (Stanford University)
We consider the online setting where a user would like to continuously release a time-series of data that is correlated with his private data, to a service provider in the hope of deriving some utility. Due to correlations, the continual observation of the released time-series puts the user at risk of inference of his private data by an adversary. To protect the user from inference attacks on his private data, the time-series is randomized prior to its release according to a probabilistic privacy mapping. The privacy mapping should be designed in a way that balances privacy and utility requirements over time.Our contributions are threefold. First, we formalize the framework for the design of utility-aware privacy mappings for time-series data, under both online and batch models. We provide a sequential scheme that allows to design online privacy mappings at scale, that account for privacy risk from the history of released data and future releases to come. Second, we prove the equivalence of the optimal mappings under the batch and the online models, in the case where the time-series samples are independent across time. We further show that there exists a gap between optimal batch and online privacy mappings when certain conditions are not satisfied.Finally, we evaluate the performance of the framework over synthetic and real-world time-series data. In particular, we show that smart-meter data can be randomized for privacy purposes to prevent disaggregation of per-device energy consumption, while preserving the utility.
Interactive Multi-Consumer Power Cooperatives with Learning and Axiomatic Cost and Risk Disaggregation
Ehsanfar, Abbas (Stevens Institute of Technology) | Heydari, Babak (Stevens Institute of Technology)
This paper introduces a novel autonomous interactive learning cooperative (ILCP) who receives expected value and variance of load from consumers and participates in the electricity market on their behalf. Using an axiomatic approach, the share of each consumer's payment as well as its weight in calculating the modification of total day-ahead load are formulated. This scheme applies double-seasonal smoothing exponential, a recent load forecasting technique, and a classifier for real-time to day-ahead price direction forecasting (Gaussian Naïve Bayes). In addition to this, the ILCP employs interactive cooperative algorithms for both trading cooperative and consumer side. The ILCP scheme is investigated and its performance is compared to those of non-cooperative real-time pricing (RTP), LCP (non-interactive learning cooperative) and CP (non-interactive non-learning cooperative). The developed system was implemented using PJM(world's largest wholesale electricity market) real-time and day-ahead data for 2013 and half of 2014; real load profiles were selected from a set of 579 residential and commercial consumers, and weather data were applied to forecasting electricity price direction. We demonstrate the advantages of ILCP to lower the average electricity cost and to reduce unit price variations.
Modeling Ecological Integrity with Bayesian Belief Networks
Barrios, Juan M. (National Commission for Knowledge and Use of Biodiversity) | Sierra-Alcocer, Raúl (National Commission for Knowledge and Use of Biodiversity) | González-Salazar, Constantino (National Commission for Knowledge and Use of Biodiversity) | Mora, Franz E. (National Commission for Knowledge and Use of Biodiversity) | Munguía, Mariana (National Commission for Knowledge and Use of Biodiversity) | Pérez-Maqueo, Octavio M. (National Commission for Knowledge and Use of Biodiversity) | Trejo, Isabel (National Commission for Knowledge and Use of Biodiversity)
Although the concept of ecological integrity is referred in many country legislations there is no consensus on how to formalize and implement it. One possible definition is as the capacity of an ecosystem to support and maintain a balanced, integrated, and adaptive community of organisms having a species composition, diversity, and functional organization comparable to that of a natural habitat of the region. Our objective is to model this interpretation of ecological integrity from a set of ecological measures that can be estimated from ecological inventory data.
Concept of a Data Thread Based Parking Space Occupancy Prediction in a Berlin Pilot Region
Tiedemann, Tim (German Research Center for Artificial Intelligence (DFKI)) | Voegele, Thomas (German Research Center for Artificial Intelligence (DFKI)) | Krell, Mario Michael (University of Bremen) | Metzen, Jan Hendrik (University of Bremen) | Kirchner, Frank (German Research Center for Artificial Intelligence (DFKI) and University of Bremen)
In the presented research project, a software and hardware infrastructure for parking space focussed inter-modal route planning in a public pilot region in Berlin is developed. One central topic is the development of a prediction system which gives an estimated occupancy for the parking spaces in the pilot region for a given date and time in the future. Occupancy data will be collected online by roadside parking sensors developed within the project. The occupancy prediction will be implemented using “Neural Gas” machine learning in combination with a proposed method which uses data threads to improve the prediction quality. In this paper, a short overview of the whole research project is given. Furthermore, the concept of the software framework and the learning methods are presented and first collected data is shown. The prediction method using data threads is explained in more detail.
Optimizing Rotorcraft Approach Trajectories with Acoustic and Land Use Models
Morris, Robert (NASA Ames Research Center) | Venable, K. Brent (Tulane University / IHMC) | Johnson, Matthew (IHMC)
Recent increase in interest in using rotorcraft (helicopters and tilt-rotor craft) for public transportation has spurred research in making rotorcraft less noisy, particularly as they land. The ground noise associated with landing trajectories followed by rotorcraft depends in part on the changes in altitude and velocity of the rotorcraft during flight. Acoustic models of ground noise taking altitude and velocity effects into account can be used in an optimization process to determine a set of potentially quieter pilot operations. However, optimizing solely for acoustic properties produces patterns that abstract away from the environment in which the trajectory is flown. A quiet procedure flown over a residential area can create considerable annoyance. To overcome this limitation of acoustic-based optimization we propose a hybrid cost model for optimization that combines acoustic criteria with a land use model that views noise-sensitive areas around landing facilities as weighted obstacles. The result is a 3D route planning problem with obstacles. We introduce a system, called NORA (Noise Optimization for Rotorcraft Approach) that allows for the computation of trajectories that simultaneously solve for acoustically quiet patterns that also avoid land sensitive areas.
Living Campus: Towards a Context-Aware Energy Efficient Campus Using Weighted Case Based Reasoning
Madkour, Mohcine (University of Houston) | Benhaddou, Driss (University of Houston) | Khalil, Nacer (University of Houston) | Burriello, Michael (University of Houston) | Raymond E. Cline, Jr. (University of Houston)
Buildings make a city’s landscape and are home to its people. The demand for smart buildings and housing is growing by the need for cities to make their buildings more efficient, green and livable. This emergent intelligence is underpinned by the use of Information and Communications Technology (ICT) linked by Pervasive Sensing and real-time data analytics. In a typical growth of smart buildings, Smart Campuses are going to be amazing community hubs which will be more sustainable, efficient and supportive of its inhabitants. In this regard, huge amount of useful and real-time generated data are being analyzed to help people and machines infer instant decisions in relation to energy efficiency. However, because of different terminologies used by different players, structural, representational and semantic heterogeneity constrain the interoperability between applications and misleads to adaptive and context-aware control behavior. In this paper, the focus is to alleviate the current problem by designing a semantic framework that represents the smart campus data and activities in an ontological model. Also, the framework is deepened by an Artificial Intelligent (AI) method using Weighted Case Based Reasoning (WCBR) for enabling context awareness. An illustration will be the elaboration of an adaptive and autonomous control of HVAC (Heating Ventilation and Air Conditioning) system, in this example the WCBR is discussed and case representation, case adaptation, and similarity computation are sketched in detail.