@conference {
	title = {Per-se Privacy Preserving Solution Methods Based on Optimization},
	author = {Weeraddana, P. C., Athanasiou, G., Fischione, Carlo., Baras, John S.},
	year = {2013},
	month = {12/2013},
	abstract = {Ensuring privacy is an essential requirement in various contexts, such as social networks, healthcare data, ecommerce, banks, and government services. Here, different entities coordinate to address specific problems where the sensitive problem data are distributed among the involved entities and no entity wants to publish its data during the solution procedure. Existing privacy preserving solution methods are mostly based on cryptographic procedures and thus have the drawback of substantial computational complexity. Surprisingly, little attention has been devoted thus far to exploit mathematical optimization techniques and their inherent properties for preserving privacy. Yet, optimization based approaches to privacy require much less computational effort compared to cryptographic variants, which is certainly desirable in practice. In this paper, a unified framework for transformation based optimization methods that ensure privacy is developed. A general definition for the privacy in the context of transformation methods is proposed. A number of examples are provided to illustrate the ideas. It is concluded that the theory is still in its infancy and that huge benefits can be achieved by a substantial development.},
	address = {Florence, Italy},
	booktitle = {52nd IEEE Conference on Decision and Control},
	pages = {pp. 206-211}
}
@conference {
	title = {Asymptotic Consensus Solutions in Non-Linear Delayed Distributed Algorithms Under Deterministic \& Stochastic Perturbations},
	author = {Somarakis, Christoforos., Baras, John S.},
	year = {2013},
	month = {12/2013},
	abstract = {We consider a multi-agent non-linear delayed model which sustains consensus type of solutions. We use fixed point theory arguments to establish sufficient conditions for existence and uniqueness of solutions that converge exponentially fast to a common value with prescribed rate. The conditions depend on the communication topology, the nonlinearity of the model as well as the delay in the propagation of information. Furthermore we test the robustness of our results in the presence of independent time varying perturbations both deterministic and stochastic.},
	address = {Florence, Italy},
	booktitle = {52nd IEEE Conference on Decision and Control},
	pages = {pp. 7821-7826}
}
@conference {
	title = {Distributed Algorithms for Optimization Problems with Equality Constraints},
	author = {Matei, Ion., Baras, John S.},
	year = {2013},
	month = {12/2013},
	abstract = {In this paper we introduce two discrete-time, distributed optimization algorithms executed by a set of agents whose interactions are subject to a communication graph. The algorithms can be applied to optimization problems where the cost function is expressed as a sum of functions, and where each function is associated to an agent. In addition, the agents can have equality constraints as well. The algorithms are not consensus-based and can be applied to non-convex optimization problems with equality constraints. We demonstrate that the first distributed algorithm results naturally from applying a first order method to solve the first order necessary conditions for a lifted optimization problem with equality constraints; the solution of our original problem is embedded in the solution of this lifted optimization problem. Using an augmented Lagrangian idea, we derive a second distributed algorithm that requires weaker conditions for local convergence compared to the first algorithm. For both algorithms we address the local convergence properties.},
	address = {Florence, Italy},
	booktitle = {52nd IEEE Conference on Decision and Control},
	pages = {pp. 2352-2357}
}
@conference {
	title = {A Distributed Learning Algorithm with Bit-valued Communications for Multi-agent Welfare Optimization},
	author = {Menon, Anup., Baras, John S.},
	year = {2013},
	month = {12/2013},
	abstract = {A multi-agent system comprising N agents, each picking actions from a finite set and receiving a payoff that depends on the action of the whole, is considered. The exact form of the payoffs are unknown and only their values can be measured by the respective agents. A decentralized algorithm was proposed by Marden et al. and in the authors{\textquoteright} earlier work that, in this setting, leads to the agents picking welfare optimizing actions under some restrictive assumptions on the payoff structure. This algorithm is modified in this paper to incorporate exchange of certain bit-valued information between the agents over a directed communication graph. The notion of an interaction graph is then introduced to encode known interaction in the system. Restrictions on the payoff structure are eliminated and conditions that guarantee convergence to welfare minimizing actions w.p. 1 are derived under the assumption that the union of the interaction graph and communication graph is strongly connected.},
	address = {Florence, Italy},
	booktitle = {Proceedings of the 52nd IEEE Conference on Decision and Control,},
	pages = {pp. 2406-2411}
}
@conference {
	title = {Coordinated Scheduling and Power Control for Downlink Cross-tier Interference Mitigation in Heterogeneous Cellular Networks},
	author = {Sung, Doo-hyun., Baras, John S., Zhu, Chenxi.},
	year = {2013},
	month = {12/2013},
	abstract = {In heterogeneous cellular networks, the deployment~of low-powered picocells provides user offloading and capacity~enhancement. The expansion of a picocell{\textquoteright}s coverage by adding~a positive bias for cell association can maximize these effects.~Under this circumstance, downlink cross-tier interference from~a macro base station to pico mobile stations in the expanded~picocell range deteriorates those pico mobile stations{\textquoteright} performance~significantly. In this paper, a coordinated scheduling~and power control algorithm is proposed, whereby the macro~base station reduces its transmission power for those victim~pico mobile stations in the expanded picocell range only on a~set of resource blocks to minimize performance degradation at~the macro base station. First, the transmission power level is~calculated based on the mobile stations{\textquoteright} channel condition and
QoS requirements. Then, a set of resource blocks is determined~by solving a binary integer programming to minimize the sum~of transmission power reduction subject to victim pico mobile~stations{\textquoteright} QoS constraints. To reduce computational complexity,~we utilize a heuristic algorithm, i.e., max-min greedy method,~to solve the problem. Through system level simulations, we~show that average and 5\%-ile throughputs of victim pico mobile~stations are significantly improved.},
	address = {Atlanta, Georgia},
	booktitle = {IEEE Globecom 2013},
	pages = {pp. 3914-3918}
}
@conference {
	title = {Distributed Trust Based Routing in Mobile Ad-Hoc Networks},
	author = {Jain, Shalabh., Baras, John S.},
	year = {2013},
	month = {11/2013},
	abstract = {Establishing trust and security in ad-hoc networkshas been a long studied problem. Several methods have beenproposed for evaluation and dissemination of trust in suchnetworks, with the goal of providing secure data paths. Wepropose a mechanism to utilize trust metrics derived from variousmethods for secure routing. Our scheme can be used in withexiting on-demand routing protocols with minimal modification.We highlight scenarios that establish the need for associating trustwith a link, rather than just a node. Our scheme incorporatesboth link and node trust to avoid adversarial paths in adistributed manner. We validate via simulation, the securityproperties of our scheme in an ad-hoc network.},
	address = {San Diego, California},
	booktitle = {2013 Military Communications Conference (MILCOM 2013)},
	pages = {pp. 1801-1807}
}
@conference {
	title = {Cerebral vasculature, Alzheimer{\textquoteright}s disease and cerebral amyloid angiopathy: What is the Connection:  A Mathematical Model},
	author = {Kyrtsos, C Rose., Baras, John S.},
	year = {2013},
	month = {11/2013},
	address = {San Diego, CA},
	booktitle = {6th International IEEE EMBS Conference on Neural Engineering}
}
@conference {
	title = {HybridSim: A Modeling and Co-simulation Toolchain for Cyber-Physical Systems},
	author = {Wang, Baobing., Baras, John S.},
	year = {2013},
	month = {10/2013},
	abstract = {Cyber-physical systems (CPS) involve communication networks, computation algorithms, control systems and physical systems. Many CPS, such as Smart Buildings, are subject to very expensive deployment costs and complex network interactions. Thus comprehensive modeling and simulation of such systems are crucial to ensure that they function as intended before deployment. Given the multi-domain nature of CPS, it is more appropriate to use a heterogeneous simulation environment to study system dynamics. In this paper, we design and implement an integrated modeling and co-simulation toolchain, called HybridSim, for the design and simulation of CPS. Firstly, HybridSim can transform and import existing system components from multi-domains into SysML, which enables systems engineers to design CPS with only these imported SysML blocks. Secondly, HybridSim can generate Functional Mock-up Units (FMUs) and configuration scripts directly from SysML designs. Finally, HybridSim can co-simulate these FMUs according to the Functional Mock-up Interface standard to synchronize their corresponding simulators and exchange information between them. We demonstrate the convenience and efficiency of HybridSim using a comprehensive hydronic heating system model for Smart Buildings as the case study to investigate the impact of packet loss and sampling rate introduced by the communication network.},
	address = {Delft, Netherlands},
	booktitle = {Proceedings of 17th IEEE/ACM International Symposium on Distributed Simulation and Real Time Applications},
	pages = {pp. 33-40}
}
@conference {
	title = {Distributed Consensus with Byzantine Adversaries},
	author = {Liu, Xiangyang., Gao, Peixin., Baras, John S.},
	year = {2013},
	month = {10/2013},
	abstract = {The problem of distributed consensus algorithms in the presence of Byzantine adversaries has been increasingly important in both distributed computing scenaria and cyber-physical systems. Yet a satisfactory solution to the problem is still being sought due to the fact that Byzantine adversaries can output arbitrary wrong states and even collude to cause worse damages. We aim to solve the problem via detecting adversaries. Related works in multi-party computation in computer science are addressing this type of problem relying on the assumption that adversaries cannot lie about their input values. Works in the control theoretic literature rely on strict and hardly verifiable network robustness conditions. Both lines of research just consider guaranteeing the consensus in the face of adversaries yet neither of them considers detecting adversaries. In this paper a method is proposed to investigate this problem based on the detection of adversaries in the execution of the consensus algorithm. We integrate a trust evaluation mechanism into the consensus algorithm, where trust can be established with the help of a special subset of nodes, namely headers. We propose a two-layer hierarchical framework, where the top layer is a super-step dealing with a vectorized consensus algorithm, and the bottom layer is a sub-step, executing our proposed parallel vectorized voting scheme. The parallel vectorized voting scheme uses the information received by the top layer as an initial trust opinion and then evolves to equilibrium trust opinions. The vectorized consensus algorithm in the top layer utilizes the trust evaluation results provided by the bottom layer to update confidence levels and states. We also derive an upper bound of the number of adversaries that our algorithm can resist in each super-step.},
	address = {Montecello, Illinois},
	booktitle = {Proceedings of 51st Annual Allerton Conference on Communication, Control and Computing}
}
@conference {
	title = {Hyperbolic Embedding to the Rescue in Communication and Social Networks},
	author = {Baras, John S.},
	year = {2013},
	month = {10/2013},
	address = {Murray Hill, NJ},
	booktitle = {2013 Bell Labs {\textendash} NIST Workshop on Large Scale Networks}
}
@conference {
	title = {The Role of Universities and Research Centers in Economic Development: Some Recommendations for Greece},
	author = {Baras, John S.},
	year = {2013},
	month = {10/2013},
	address = {Athens, Greece},
	booktitle = {1st Conference of the Hellenic Innovation Forum, Eugenides Foundation}
}
@conference {
	title = {A Rigorous Framework for Model-Based Systems Engineering and Applications},
	author = {Baras, John S.},
	year = {2013},
	month = {09/2013},
	address = {Niskayuna, NY},
	booktitle = {General Electric Global Controls Symposium}
}
@conference {
	title = {A Coalitional Game Based Approach for Multi-Metric Optimal Routing in Wireless Networks},
	author = {Stai, Eleni., Papavassiliou, Symeon., Baras, John S.},
	year = {2013},
	month = {09/2013},
	abstract = {Future communications consist of an increasing number of wireless parts, while simultaneously need to support the widespread multimedia applications imposed by social networks. These human-machine systems, driven by both real time social interactions and the challenges of the wireless networks{\textquoteright} design, call for efficient and easy to implement, distributed cross-layer algorithms for their operation. Performance metrics such as throughput, delay, trust, energy consumption, need to be improved and optimized aiming at high quality communications. We investigate the coveted throughput-delay trade-off in static wireless multihop networks based on a {\textquotedblleft}computer-aided{\textquotedblright} design of the backpressure scheduling/routing algorithm for networks embedded in hyperbolic space. Both routing and scheduling exploit the hyperbolic distances to orient the packets to the destination and prioritize the transmissions correspondingly. The proposed design provides us with the freedom of controlling its theoretical throughput optimality and of counterbalancing its practical performance through simulations, leading to significant improvements of the throughput-delay trade-off.},
	address = {London, UK},
	booktitle = {Proceedings of IEEE 22nd International Symposium on Personal, Indoor and Mobile Radio Communications: Mobile and Wireless Networks},
	pages = {pp. 1935-1939}
}
@conference {
	title = {On The Convergence Rate of Non-Linear Consensus Networks with Delays},
	author = {Somarakis, Christoforos., Baras, John S.},
	year = {2013},
	month = {09/2013},
	abstract = {We consider a generic non-linear consensus model and prove convergence results to a common value together with prescribed rate of convergence. Instead of a Lyapunov approach we consider a functional metric space and make a fixed point theory argument using contraction mappings. We are restricted to the case of static networks.},
	address = {Toulouse, France},
	booktitle = {9th IFAC Symposium on Nonlinear Control Systems,},
	pages = {pp. 705-710}
}
@conference {
	title = {On the connectivity assumption of non-liner flocking models},
	author = {Somarakis, Christoforos., Baras, John S.},
	year = {2013},
	month = {08/2013},
	abstract = {The problem of collective behavior of autonomous agents is discussed. Based on state dependent communication graphs we analyze a family of nonlinear flocking models by establishing sufficient initial conditions so as connectivity and thus asymptotic flocking is ensured. We discuss models with non-linear uniformly bounded connection rates with and without delays.},
	address = {Mi{\k e}dzyzdroje, Poland},
	booktitle = {Proceedings of 8th International Conference on Methods and Models is Automation and Robotics (MMAR 2013)},
	pages = {pp. 800-805}
}
@conference {
	title = {On the connectivity of non-liner flocking models},
	author = {Somarakis, Christoforos., Baras, John S.},
	year = {2013},
	month = {08/2013},
	abstract = {The problem of collective behavior of autonomous agents is discussed. Based on state dependent communication graphs we analyze a family of nonlinear flocking models by establishing sufficient initial conditions so as connectivity and thus asymptotic flocking is ensured. We discuss models with non-linear uniformly bounded connection rates with and without delays.},
	address = {Mi{\k e}dzyzdroje, Poland},
	booktitle = {18th International Conference on Methods and Models is Automation and Robotics (MMAR 2013)},
	pages = {pp. 800-805}
}
@conference {
	title = {The Promise and Challenges of {\textquotedblleft}Smart{\textquotedblright} Health Information Technology},
	author = {Baras, John S.},
	year = {2013},
	month = {08/2013},
	address = {Beijing, China},
	booktitle = {2nd International Workshop on Artificial Intelligence and Netmedicine (NetMed{\textquoteright}13), part of 23rd International Joint Conference on Artificial intelligence (IJCAI)}
}
@conference {
	title = {Fixed Point Theory Approach to Exponential Convergence in LTV Continuous Time Consensus Dynamics with Delays},
	author = {Somarakis, Christoforos., Baras, John S.},
	year = {2013},
	month = {07/2013},
	abstract = {The problem of continuous linear time varying consensus dynamics is addressed in the presence of constant communication delays. We make a Fixed Point Theory argument with the use of contraction mappings and we state sufficient conditions for exponential convergence to a consensus value with prescribed convergence rate.},
	address = {San Diego, CA},
	booktitle = {SIAM conference on Control and its Application 2013},
	pages = {pp. 129-136}
}
@conference {
	title = {Universities and Research Centers as Agents for Economic Development},
	author = {Baras, John S.},
	year = {2013},
	month = {07/2013},
	address = {Athens, Greece},
	booktitle = {1st Hellenic Forum for Science, Technology and Innovation},
	organization = {NCSR Demokritos}
}
@conference {
	title = {LTI Continuous Time Consensus Dynamics with Multiple and Distributed Delays},
	author = {Somarakis, Christoforos., Baras, John S.},
	year = {2013},
	month = {06/2013},
	abstract = {We study linear time invariant (LTI) continuous time consensus dynamics in the presence of bounded communication delays. Contrary to traditional Lyapunov based methods, we approach the problem using Fixed Point Theory. This method, allows us to create an appropriate complete functional metric space and through contraction mappings to establish the existence and uniqueness of a solution of this model. We explore the case of constant as well as distributed delays.},
	address = {Platanias-Chania, Crete - GREECE},
	booktitle = {21st Mediterranean Conference on Control and Automation},
	pages = {pp. 1495-1501}
}
@conference {
	title = {Impact of Protocols on Traffic Burstiness At Large Timescales in Wireless Multi-Hop Networks},
	author = {Jain, Kaustubh., Baras, John S.},
	year = {2013},
	month = {06/2013},
	abstract = {We investigate the impact of the protocol stack on traffic burstiness at large time-scales in wireless multi-hop network traffic. Origins of traffic burstiness at large scales (like its LRD nature) have been mostly attributed to the heavy-tails in traffic sources. In wired networks, protocol dynamics have little impact on large time-scale dynamics. However, given the nature wireless networks, the MAC and routing layers together can lead to route flapping or oscillations even in a static network.Hence, we explore whether these dynamics can lead to trafficburstiness and LRD. Using network simulations, we analyze traffic for two MANET routing protocols - OLSR and AODV. By varying the routing protocol parameters, we analyze their role in inducing or preventing route oscillations, and study their impact on traffic LRD. We find that, losses in OLSR control packets, due to congestion at the MAC, can lead to route oscillations and trafficburstiness at large timescales. By tuning the parameters, route oscillations and traffic LRD can be avoided. AODV dynamics show little evidence for traffic LRD, even though we cannot rule out this possibility. We also show that the route oscillations can have heavier body and tail than exponential distribution, and that the Markovian framework for route oscillations is inadequate to explain the observed traffic scaling. Lastly, we give a model that captures the MAC and OLSR routing protocol interactions and depending upon chosen protocol parameters and input load,correctly predicts the presence of traffic LRD. Thus, we use this model to design appropriate choice of protocol parameters to mitigate traffic burstiness at large-timescales.},
	address = {Corsica, France},
	booktitle = {IEEE 2013 The 12th Annual Mediterranean Ad Hoc Networking Workshop (Med-Hoc-Net)},
	pages = {pp. 61-68},
	organization = {Ajaccio}
}
@conference {
	title = {Convergence Guarantees for a Decentralized Algorithm Achieving Pareto Optimality},
	author = {Menon, Anup., Baras, John S.},
	year = {2013},
	month = {06/2013},
	abstract = {We consider N agents, each picking actions froma finite set and receiving a payoff according to its individualutility function that may depend on the actions picked byothers. An agent has no knowledge about the functional formof its utility and can only measure its instantaneous value.It is assumed that all agents pick actions and receive payoffssynchronously. For this setting, a fully decentralized iterativealgorithm for achieving Pareto optimality i.e. picking actionsthat maximize the sum of all utilities was proposed by Mardenet. al. in [1] that lacks convergence guarantees. By schedulinga certain noise parameter to go to zero along iterations of thisalgorithm, conditions that guarantee convergence in probabilityare derived in this paper.},
	address = {Washington DC},
	booktitle = {2013 American Control Conference},
	pages = {pp. 1935-1940}
}
@conference {
	title = {Correlating Photovoltaic Clear-Sky and Actual Output to Sky Cover Measurements},
	author = {Daily, David R., Holmberg, David G., Baras, John S.},
	year = {2013},
	month = {06/2013},
	abstract = {As distributed energy resources are added to building systems, and variable priced electricity tariffs are introduced, facility owners may profit from understanding the expected performance of their building systems. Hourly, forecast energy generation data from photovoltaic sources allows owners to manage energy storage and consumption for their optimal benefit. This paper documents an empirical method which uses publicly{\textendash}available sky cover observations to estimate the output of a photovoltaic (PV) array. Two functions are developed which together relate PV array output to sky cover observations reported by the National Oceanic and Atmospheric Administration{\textquoteright}s National Weather Service (NWS) for a nearby airport. Results are evaluated by comparison of estimated PV array output with actual output. Results show this approach can produce useful estimates of hourly and daily PV system output which may be applied to forecast weather data in order to manage PV array outputs. Although some large deviations are observed between forecast and actual PV output, the method presented uses data that would be available to a building owner with insufficient on-site instrumentation beyond a meter.},
	address = {Tampa, Florida},
	booktitle = {To appear in the proceedings of 39th IEEE Photovoltaic Specialists Conference}
}
@conference {
	title = {A Fresh Look at Network Science: Coevolving Multigraphs, Multiple Semirings and Coalitional Games},
	author = {Baras, John S.},
	year = {2013},
	month = {06/2013},
	address = {Budapest, Hungary},
	booktitle = {Networking Across Disciplines: Communication Networks,  Complex Systems and Statistical Physics (NETSTAT)  workshop}
}
@conference {
	title = {{\textquotedblleft}Hardware{\textquotedblright} {\textendash} Software Security},
	author = {Baras, John S.},
	year = {2013},
	month = {06/2013},
	address = {San Francisco, CA},
	booktitle = {2013 INTEL University Collaboration Symposium}
}
@conference {
	title = {Fundamental Challenges in Modeling and Design Space Exploration for CPS},
	author = {Baras, John S.},
	year = {2013},
	month = {05/2013},
	address = {Austin, Texas},
	booktitle = {2nd International Workshop on Analytics for Cyber-Physical Systems (ACS-2013)}
}
@conference {
	title = {An Approach to Model-Based Systems Engineering with Applications to Army Ground and Air Vehicles, Single or Collaborating},
	author = {Baras, John S.},
	year = {2013},
	month = {04/2013},
	address = {Aberdeen Proving Grounds, Maryland},
	booktitle = {RDECOM}
}
@conference {
	title = {Security and Trust in a Networked Immersed World: From Components to Systems and Beyond},
	author = {Baras, John S.},
	year = {2013},
	month = {04/2013},
	abstract = {The tremendous explosion of wireless devices and services have created unprecedented advances and are impacting every aspect of life and work. However, many of these advances and resulting expanding markets are critically endangered by weaknesses in security, integrity, and trust. We first describe several of these emerging systems and markets in areas ranging from aerospace and automotive to healthcare and e-commerce to social networks over the Web. We then describe various physical layer (e.g. hardware and signal processing) techniques that can be successfully utilized to significantly strengthen the security of wireless devices and networked systems. We argue for the need of a {\textquotedblleft}trusted core{\textquotedblright} in wireless networks and for the allocation of part of the security functionality to the physical layer. We next turn to the subject of trust in large networks and describe a new framework using multiple partially ordered semirings for analyzing reputation and trust dynamics and composite trust. Next, we describe our work based on constrained coalitional games towards understanding the role of trust in collaboration and social networks. We describe several specific applications of these methods in securing distributed inference systems, SCADA sensor networks for power grids, wireless network routing protocols, LTE paging systems, wireless handheld devices for healthcare and e-payment systems. We close by describing the need for rigorous frameworks and theories for composable security and outline how these physical layer techniques can provide the foundation for such developments.},
	address = {College Park, MD},
	booktitle = {Laboratory for Telecommunication Sciences (LTS)}
}
@conference {
	title = {Model-Based Systems Enginnering Approach to Energy Efficient Building Design},
	author = {Daily, David R., Baras, John S.},
	year = {2013},
	month = {04/2013},
	abstract = {PROJECT

During my senior year at the University of Maryland, I was challenged to develop and investigate a research question utilizing Systems Engineering methodologies and tools for my capstone project. My project uses Model-Based Systems Engineering to model and simulate a residential building{\textquoteright}s HVAC operational effect and perform trade-off analysis on the building parameters. I have since continued this research for my Masters of Science in Systems Engineering thesis.

PURPOSE

According to the U.S. Energy Information Administration{\textquoteright}s (EIA) {\textquotedblleft}Annual Energy Outlook 2012{\textquotedblright}, the residential and commercial sectors use a combined 28 percent of total U.S. energy consumption. With energy efficiency technology improvements and policy change, the EIA estimates that building energy consumption could be reduced by 10\%-18.5\% within these sectors by 2035. Reducing building energy demand is a necessary step in curbing the greenhouse gas issue and creates new requirements to meet these goals. Model-Based System Engineering allows for easy requirements verification and validation while creating a truly optimized system.

METHODOLOGY

I used Systems Modeling Language (SysML) to develop a model of the building, its components, and other inputs into the system (i.e. weather). I am able to create a robust model in the SysML program MagicDraw, including detailed parametric, activity, and sequence diagrams, along with significant requirements definitions. I made a basic thermodynamics simulation in MATLAB and linked the two programs. With this link established, I automated the parametric analysis of the building parameters. The resulting 846 iterations gave me performance data to perform trade-off analysis to optimize cost and energy efficiency.

RESULTS

When the setpoint temperature of the building is outside the allowable range, the HVAC system uses energy to condition the space, while thermal losses and gains vary the indoor temperature. The efficiency metric is defined as the period length between the activation of the HVAC system. A longer period indicates a more energy efficient system. Through trade-off analysis, I conclude that the parameter of insulation R-Value had the greatest cost-to-efficiency benefit while window U-Value had the second most impact.},
	address = {La Crosse, WI},
	booktitle = {National Conference on Undergradute Research (NCUR) 2013}
}
@conference {
	title = {Storage-centric Sensor Networks for Smart Buildings},
	author = {Wang, Baobing., Baras, John S.},
	year = {2013},
	month = {04/2013},
	abstract = {In my thesis, I propose a model-based systems design framework, called WSNDesign, to facilitate the design and implementation of wireless sensor networks (WSNs). WSNDesign provides a hierarchy of model libraries to model various behaviors and structures of WSNs in the context of Smart Buildings, and introduces a system design flow to compose both continuous-time and event-triggered modules to develop applications with support for performance evaluation. In order to handle various sensor data efficiently, WSNDesign provides a distributed database system, called HybridDB, for data collection and retrieval. HybridDB enables sensors to store large-scale datasets in situ on local NAND ash using a novel resource-aware data storage system, and can process typical queries inWSNs extremely efficiently. In addition, HybridDB supports incremental -approximate querying that enables clients to retrieve a just-sufficient set of sensor data by issuing refinement and zoom-in sub-queries to search events and analyze sensor data efficiently. HybridDB can always return an approximate dataset with guaranteed L1-norm error bound.},
	address = {Philadelphia, PA},
	booktitle = {12th ACM/IEEE Conference on Information Processing in Sensor Networks IPSN 2013}
}
@conference {
	title = {Extending Design Capabilities of SysML with Trade-off Analysis: Electrical Microgrid Case Study},
	author = {Spyropoulos, Dimitrios., Baras, John S.},
	year = {2013},
	month = {03/2013},
	abstract = {Changes in technology, economy and society create challenges that force us to rethink the way we develop systems. Model- Based Systems Engineering is an approach that can prove catalytic in this new era of systems development. In this paper we introduce the idea of the {\textquotedblleft}modeling hub{\textquotedblright} in order to realize the vision of Model-Based Systems Engineering and especially we focus on the trade-off path of this hub. For that purpose the design capabilities of SysML are extended by integrating it with Consol-Optcad, a powerful multi-criteria optimization tool for trade-off analysis. The integration and its implementation is applied to analyze a multi-criteria optimization problem concerning power allocation and scheduling in a microgrid.},
	address = {Atlanta, GA},
	booktitle = {Conference on Systems Engineering Research (CSER{\textquoteright}13),},
	pages = {pp. 108-117}
}
@conference {
	title = {Compositional Analysis of Dynamic Bayesian Networks and Applications to Complex Dynamic System Decomposition},
	author = {Yang, Shahan., Zhou, Yuchen., Baras, John S.},
	year = {2013},
	month = {03/2013},
	abstract = {Dynamic Bayesian networks (DBNs) can be effectively used to model various problems in complex dynamic systems. We perform an empirical investigation on compositional analysis of DBNs using abstraction. In static systems and hidden Markov models, computation of a metric called treewidth induces a tree decomposition that can be used to perform logical or probabilistic inference and max + optimizations in time exponential in treewidth and linear in overall system size. Intuitively, the linear scaling means that very large systems can be analyzed as long as they are sufficiently sparse and well structured. In these simple cases, summary propagation, which uses two operations, summation (projection) and product (composition), suffices to perform the inference or optimization. Here, we begin an extension of this to structured networks of communicating dynamic systems. We define generalizations of projection and composition operators that treat labeled Markov chains as primitive objects. The projection operation, corresponding to summation, is implemented as label deletion followed by exact state reduction for Markov chains, similar to Hopcroft{\textquoteright}s DFA minimization algorithm, with O(n log m) complexity. The composition operation is the product of state machines. We use canonical MDDs, similar to BDDs, to capture logical dependencies symbolically. Combining symbolic representations with Markov chain lumping algorithms is a novel contribution. Using this approach, we have created a tool leveraging model based systems engineering technologies. The communicating Markov chains are specified using UML Statecharts via Papyrus extended using an ANTLR parsed domain specific language (DSL). The tool reduces the number of states in networks of Markov chains by several orders of magnitude. In one example, a network having a product state space of more than 600 million states is reduced to about 500 states. A feature of this technique is that the state space is examined incrementally, meaning that the full state space is never explicitly represented, even as an input to the reduction algorithm. The primary reduction appears to come from symmetry which is surprising because the technique includes no explicit symmetry handling. We note that composition is efficient at least for systems with high symmetry. We describe applications to a hospital intensive care unit (ICU) from a systems engineering perspective.},
	address = {Atlanta, GA},
	booktitle = {Conference on Systems Engineering Research (CSER{\textquoteright}13),},
	pages = {pp. 167-176}
}
@conference {
	title = {Interactive Tree Decomposition Tool for Reducing System Analysis Complexity},
	author = {Yang, Shahan., Wang, Baobing., Baras, John S.},
	year = {2013},
	month = {03/2013},
	abstract = {We present a graphical tool for the calculation of treewidth, a metric on the parametric structure of a system that is intimately tied to the complexity of system analysis. For many graphically describable systems, such as systems of parametric equations, as in a SysML Parametric diagram, or Bayesian networks or even mind maps and writing term papers, analysis of the system is exponential in treewidth and linear in system size. A tool facilitating comprehensive analysis can serve to bring competitive advantage to a systems engineering workflow by reducing costly unanticipated behaviors. Furthermore, a byproduct of computing treewidth is a framework for enumerating computationally compatible distributed algorithms. In this paper, we pose this NP-complete problem from the perspective of finding satisficing solutions, exposing choices that can influence the complexity of the resulting system to the designer. A designer can contribute two important things to the structure of the system: a visual intuition about the relationships between the underlying objects and the ability to change the relationships themselves at design time to reduce analysis complexity. Having a visual tool that provides instant feedback will help designers achieve an intuitive grasp of the relationship between design decisions and system complexity. As complexity is the root of almost every systems engineering problem, and also something not easily understood, incorporating complexity analysis into a design process should improve resulting system designs. The tool uses a randomized, anytime algorithm for interactive optimization of treewidth. It presents a sequence of choices to a designer and incrementally lowers an upper bound on system treewidth over time. This algorithm is novel, as few algorithms are targeted at interactivity with a human user. We present a number of simple examples for using the tool. We show how our tool helps to decompose some example systems, including a quadrotor optimization, a sensor network optimization, a Bayesian network, and a mind map.},
	address = {Atlanta, GA},
	booktitle = {Conference on Systems Engineering Research (CSER{\textquoteright}13),},
	pages = {pp. 138-147}
}
@conference {
	title = {Studying the role of Apoe in Alzheimer{\textquoteright}s disease pathogenesis using a systems biology model},
	author = {Kyrtsos, C Rose., Baras, John S.},
	year = {2013},
	month = {03/2013},
	abstract = {Alzheimer{\textquoteright}s disease (AD) is the most common form of dementia. Even with its well-known symptoms of memory loss and well-characterized pathology of beta amyloid (A) plaques and neurofibrillary tangles, the disease pathogenesis and initiating factors are still not well understood. To tackle this problem, a systems biology model has been developed and used to study the varying effects of variations in the ApoE allele present, as well as the effects of short term and periodic inflammation at low to moderate levels. Simulations showed a late onset peak of A in the ApoE4 case that lead to localized neuron loss which could be ameliorated in part by application of short-term pro-inflammatory mediators. The model that has been developed herein represents one of the first attempts to model AD from a systems approach to study physiologically relevant parameters that may prove useful to physicians in the future.},
	address = {Honolulu, Hawaii},
	booktitle = {5th International Conference on Bioinformatics and Computational Biology (BICoB)},
	pages = {pp. 1342003-1 -1342003-21}
}
@conference {
	title = {HybridStore: An Efficient DataManagement System for Hybrid Flash-based Sensor Devices},
	author = {Wang, Baobing., Baras, John S.},
	year = {2013},
	month = {02/2013},
	abstract = {In this paper, we propose HybridStore, a novel efficient resourceaware data management system for flash-based sensor devices to store and query sensor data streams. HybridStore has three key features. Firstly, it takes advantage of the on-board random-accessible NOR flash in current sensor platforms to guarantee that all NAND pages used by it are fully occupied and written in a purely sequential fashion, and expensive in-place updates and out-of-place writes to an existing NAND page are completely avoided. Thus, both raw NAND flash chips and FTL-equipped (Flash Translation Layer) flash packages can be supported efficiently. Secondly, HybridStore can process typical joint queries involving both time windows and key value ranges as selection predicate extremely efficiently, even on large-scale datasets. It organizes a data stream into segments and exploits a novel index structure that consists of the inter-segment skip list, and the in-segment β-Tree and Bloom filter of each segment. Finally, HybridStore can trivially support time-based data aging without any extra overhead because no garbage collection mechanism is needed. Our implementation and evaluation with a large-scale real-world dataset in TinyOS reveals that HybridStore can achieve remarkable performance at a small cost of constructing the index.},
	address = {Ghent, Belgium},
	booktitle = {10th European Conference on Wireless Sensor Networks},
	pages = {pp. 50-66}
}
@conference {
	title = {Security and Trust in a Networked Immersed World: from Components to Systems and Beyond},
	author = {Baras, John S.},
	year = {2013},
	month = {01/2013},
	address = {Stockholm, Sweden},
	booktitle = {3rd ACCESS Industry Workshop},
	organization = {KTH, Royal Institute of Technology}
}
@conference {
	title = {Hyperbolic Embedding to the Rescue in Communication Networks Control},
	author = {Baras, John S.},
	year = {2013},
	month = {01/2013},
	address = {Lund, Sweden},
	organization = {Lund University}
}
