Computer Engineering Commons^™

Idpal – A Partially-Adiabatic Energy-Efficient Logic Family: Theory And Applications To Secure Computing, Mihail T. Cutitaru

Electrical & Computer Engineering Theses & Dissertations

Low-power circuits and issues associated with them have gained a significant amount of attention in recent years due to the boom in portable electronic devices. Historically, low-power operation relied heavily on technology scaling and reduced operating voltage, however this trend has been slowing down recently due to the increased power density on chips. This dissertation introduces a new very-low power partially-adiabatic logic family called Input-Decoupled Partially-Adiabatic Logic (IDPAL) with applications in low-power circuits. Experimental results show that IDPAL reduces energy usage by 79% compared to equivalent CMOS implementations and by 25% when compared to the best adiabatic implementation. Experiments ranging …

Creating Autonomous Adaptive Agents In A Real-Time First-Person Shooter Computer Game, Di Wang, Ah-Hwee Tan

Research Collection School Of Computing and Information Systems

Games are good test-beds to evaluate AI methodologies. In recent years, there has been a vast amount of research dealing with real-time computer games other than the traditional board games or card games. This paper illustrates how we create agents by employing FALCON, a self-organizing neural network that performs reinforcement learning, to play a well-known first-person shooter computer game called Unreal Tournament. Rewards used for learning are either obtained from the game environment or estimated using the temporal difference learning scheme. In this way, the agents are able to acquire proper strategies and discover the effectiveness of different weapons without …

Lifetime Lexical Variation In Social Media, Lizi Liao, Jing Jiang, Ying Ding, Heyan Huang, Ee-Peng Lim

Research Collection School Of Computing and Information Systems

As the rapid growth of online social media attracts a large number of Internet users, the large volume of content generated by these users also provides us with an opportunity to study the lexical variation of people of different ages. In this paper, we present a latent variable model that jointly models the lexical content of tweets and Twitter users' ages. Our model inherently assumes that a topic has not only a word distribution but also an age distribution. We propose a Gibbs-EM algorithm to perform inference on our model. Empirical evaluation shows that our model can learn meaningful age-specific …

Click-Through-Based Cross-View Learning For Image Search, Yingwei Pan, Ting Yao, Tao Mei, Houqiang Li, Chong-Wah Ngo, Yong Rui

Research Collection School Of Computing and Information Systems

One of the fundamental problems in image search is to rank image documents according to a given textual query. Existing search engines highly depend on surrounding texts for ranking images, or leverage the query-image pairs annotated by human labelers to train a series of ranking functions. However, there are two major limitations: 1) the surrounding texts are often noisy or too few to accurately describe the image content, and 2) the human annotations are resourcefully expensive and thus cannot be scaled up. We demonstrate in this paper that the above two fundamental challenges can be mitigated by jointly exploring the …

High Dimensional Data Set Analysis Using A Large-Scale Manifold Learning Approach, Loc Tran

Electrical & Computer Engineering Theses & Dissertations

Because of technological advances, a trend occurs for data sets increasing in size and dimensionality. Processing these large scale data sets is challenging for conventional computers due to computational limitations. A framework for nonlinear dimensionality reduction on large databases is presented that alleviates the issue of large data sets through sampling, graph construction, manifold learning, and embedding. Neighborhood selection is a key step in this framework and a potential area of improvement. The standard approach to neighborhood selection is setting a fixed neighborhood. This could be a fixed number of neighbors or a fixed neighborhood size. Each of these has …

Stochastic Analysis Of Cascading-Failure Dynamics In Power Grids, Mahshid Rahnamay-Naeini, Zhuoyao Wang, Nasir Ghani, Andrea Mammoli, Majeed M. Hayat

Electrical and Computer Engineering Faculty Research and Publications

A scalable and analytically tractable probabilistic model for the cascading failure dynamics in power grids is constructed while retaining key physical attributes and operating characteristics of the power grid. The approach is based upon extracting a reduced abstraction of large-scale power grids using a small number of aggregate state variables while modeling the system dynamics using a continuous-time Markov chain. The aggregate state variables represent critical power-grid attributes, which have been shown, from prior simulation-based and historical-data-based analysis, to strongly influence the cascading behavior. The transition rates among states are formulated in terms of certain parameters that capture grid's operating …

Anisotropy Modulations Of Femtosecond Laser Pulse Induced Periodic Surface Structures On Silicon By Adjusting Double Pulse Delay, Weina Han, Lan Jiang, Xiaowei Li, Qingsong Wang, Hao Li, Yongfeng Lu

Department of Electrical and Computer Engineering: Faculty Publications

We demonstrate that the polarization-dependent anisotropy of the laser-induced periodic surface structure (LIPSS) on silicon can be adjusted by designing a femtosecond laser pulse train (800 nm, 50 fs, 1 kHz). By varying the pulse delay from 100 to 1600 fs within a double pulse train to reduce the deposited pulse energy, which weakens the directional surface plasmon polarition (SPP)-laser energy coupling based on the initial formed ripple structure, the polarization-dependent geometrical morphology of the LIPSS evolves from a nearly isotropic circular shape to a somewhat elongated elliptical shape. Meanwhile, the controllable anisotropy of the two-dimensional scanned-line widths with different …

From The Editor-In-Chief, Ibrahim A. Baggili

Journal of Digital Forensics, Security and Law

We are proud to share with you this special edition issue of the JDFSL. This year, JDFSL partnered with both the 6th International Conference on Digital Forensics and Cyber Crime (ICDF2C) and Systematic Approaches to Digital Forensic Engineering (SADFE)–two prominent conferences in our field that were co-hosted. Fifty-three papers were submitted, and the Technical Program Committee accepted only 17 after a rigorous review process.

The Impact Of Fuzzy Requirements On Medical Device Software Development, Martin Mchugh, Abder-Rahman Ali, Fergal Mccaffery

Conference papers

Any software development project can experience difficulties with unclear or vague requirements. Unfortunately, this problem can be experience two fold in regulated environments such as the medical device software development industry. In the medical device software development industry, development organisations must contend with vague or “fuzzy” both the customer and regulatory bodies. As new requirements are introduced they can have a knock on effect on other requirements. These requirements should be analysed to determine if they are conflicting, cooperative, mutually exclusive and irrelevant. Only when the requirement is classified can a clear method be established as how to integrate that …

Story Guided Virtual Cultural Heritage Applications, Selma Rizvic

Journal of Interactive Humanities

Virtual cultural heritage applications, particularly virtual museums, nowadays include various forms of storytelling. Every object, site or artifact is better perceived and understood through the adjoining story. Interactive applications naturally request the storytelling to become interactive as well. This paper describes the concepts of interactive digital storytelling in our virtual museums and cultural heritage presentations and discusses their advantages and drawbacks recognized through user evaluation. We used digital stories not only to introduce visitors with the context and information on the objects, but also to enhance their navigation through virtual environments with purpose of learning and perceiving maximum amount of …

Terahertz Photoacoustic Spectroscopy Using An Mems Cantilever Sensor, Nathan E. Giauvitz, Ronald A. Coutu Jr., Ivan R. Medvedev, Douglas T. Petkie

Electrical and Computer Engineering Faculty Research and Publications

In this paper, a microelectromechanical systems cantilever sensor was designed, modeled, and fabricated to measure the photoacoustic (PA) response of gases under very low vacuum conditions. The micromachined devices were fabricated using silicon-on-insulator wafers and then tested in a custom-built, miniature, vacuum chamber during this first-ever demonstration. Terahertz radiation was amplitude modulated to excite the gas under test and perform PA molecular spectroscopy. Experimental data show a predominantly linear response that directly correlates measured cantilever deflection to PA signals. Excellent low pressure (i.e., 2-40 mTorr) methyl cyanide PA spectral data were collected resulting in a system sensitivity of 1.97 × …

Deterministic Versus Randomized Kaczmarz Iterative Projection, Tim Wallace, Ali Sekmen

Computer Science Faculty Research

The Kaczmarz’s alternating projection method has been widely used for solving a consistent (mostly over-determined) linear system of equations Ax = b. Because of its simple iterative nature with light computation, this method was successfully applied in computerized tomography. Since tomography generates a matrix A with highly coherent rows, randomized Kaczmarz algorithm is expected to provide faster convergence as it picks a row for each iteration at random, based on a certain probability distribution. It was recently shown that picking a row at random, proportional with its norm, makes the iteration converge exponentially in expectation with a decay constant that …

Integration Of Models For Low Carbon Economy, Getachew F. Belete, Alexey Voinov

International Congress on Environmental Modelling and Software

Designing the transition to low carbon economy is a very complex task that touches upon a wide variety of climate-energy-economic systems. We need to explore the various possible climate mitigation scenarios at different temporal and spatial scales. However, due to the diversity of the involved disciplines it is difficult to find one complete and unified modeling approach that works equally well in all those different domains. As a result we have to select 'appropriate' models, which represent only specific aspects of the scenarios and assemble them 'coherently'. In this research we have identified some challenges in integrating multidisciplinary models; and …

A Decision Support System Approach For Identifying Poliutant Source For Optimization Of Beneficial Management Practices Scenario Modelling In Lake Winnipeg Watersheds, Isaac Wong, Luis Leon, Jason Vanrobaeys, Craig Mccrimmon, Phil Fong

International Congress on Environmental Modelling and Software

The Soil and Water Assessment Tool (SWAT) results can be used to source trace loading "hotspots• for optimally locating beneficial management practices (BMP). It is possible to trace upstream and compute the relative contribution of each sub-basin to a point of interest, accounting for in-stream processes, reservoirs and point sources. A decision support system (DSS) framework was developed to run SWAT, perform the otherwise tedious process of source tracing "hotspots" and to optimize BMP locations. The "Crop to Hay- land use change BMP scenario was applied in an attempt to reduce annual loadings of total phosphorus (TP) for three Lake …

Agroecosystem-Watershed (Ages-W) Model Delineation And Scaling, Timothy R. Green, Robert H. Erskine, James C. Ascough Ii, Bruce Vandenberg, Björn Pfennig, Holm Kipka, Olaf David, Micheal L. Coleman

International Congress on Environmental Modelling and Software

Water movement and storage within an agricultural watershed can be simulated at different spatial resolutions of land areas or hydrological response units (HRUs). Interactions between HRUs in space and time vary with the HRU sizes, such that natural scaling relationships are confounded with the simulation scales. Scaling concepts can be tested using the AgroEcoSystem­ Watershed (AgES-W) model with different resolutions of HRUs. Here, we delineated a 56-ha agricultural watershed in northern Colorado, USA farmed primarily under a wheat-fallow rotation. Factors used to distinguish HRUs included topography (surface flow paths), land use (crop strips and native grass), and mapped soil units …

Global Sensitivity Analysis Of Key Parameters In A Process-Based Sugarcane Growth Model - A Bayesian Approach, Justin Sexton, Yvette Everingham

International Congress on Environmental Modelling and Software

While several statistical methods are available to analyse model sensitivity, their application to complex process-based models is often impractical due to the large number of simulation runs required. A Bayesian approach to global sensitivity analysis can greatly reduce the number of simulation runs required by building an emulator of the model which is less computationally demanding. A Gaussian Emulation Machine (GEM) was used to efficiently assess the sensitivity of key agronomic outputs from the APSIM-Sugar crop model to influential input parameters. The sensitivity of simulated biomass and sucrose at harvest was assessed on 14 parameters representing varietal differences and growth …

Dynamic Feedback Between Land Use And Hydrology For Ecosystem Services Assessment, Seleshi Getahun Yalew, Tobias Pilz, Christian Schweitzer, Stefan Liersch, Johannes Van Der Kwast, Marloes L. Mul, Ann Van Griensven, Pieter Van Der Zaag

International Congress on Environmental Modelling and Software

Ecosystem services assessment requires an integrated approach, as it is influenced by elements such as climate, hydrology and socio-economics, which in turn influence each other. However, there are few studies that integrate these elements in order to assess ecosystem services. Absence of integrated approach to modelling hydrological and land-use changes, for instance, often oversights the dynamic feedback between the two processes. Dynamic changes in land-use should be fed into hydrological models and vice-versa at each time-step for a more realistic representation. In this study, this approach is demonstrated with a case study of the uThukela catchment, South Africa. There is …

Ontology Mapping In Semantic Time Series Processing In Climate Change Prediction, Bojan Božić, Jan Peters-Anders, Gerald Schimak

International Congress on Environmental Modelling and Software

In today's time series processing there is more and more a need for addressing diverse user groups interested in a specific domain with appropriate user tailored time series data. The complexity of time series (e.g. involved data from different data sources and/or domains, visualization and representation, etc.) is growing rapidly. As a consequence, it means that users need to find a path through the jungle of time series data. After we have presented our concepts for semantic time series filtering and enrichment of time series with meta-information and annotations (Božić et al., 2012), we are now going to present a …

Metadata Extraction Using Semantic And Natural Language Processing Techniques, Rob Knapen, Thomas Hüsing, Klaus Jacob, Yke Van Randen, Stefan Reis, Onno Roosenschoon, Sander Janssen

International Congress on Environmental Modelling and Software

The World Wide Web and related technologies are playing an increasing role in the field of Integrated Environmental Modelling (IEM). Model integration software frameworks are more and more becoming web-enabled. The technologies and standards of the Web are used to access and run simulation models remotely (known as the Web of models) and are considered for enabling interoperability across model integration frameworks. Furthermore there is a growing number of local and global initiatives to provide open access to environmental data (Web of data) that can potentially be used as input for the scientific models. The availability of descriptive information of …

Improved Implicit Stochastic Optimization Technique For Multireservoir Water Systems Under Drought Conditions, Andrea Sulis

International Congress on Environmental Modelling and Software

Drought is a creeping phenomenon, making its onset and end difficult to determine. Damages from droughts can exceed those resulting from any other natural hazard, although it is difficult to assign a monetary value to them. In the Mediterranean area a severe drought period occurred over the years 2000-2002 and economic losses from that drought exceeded 250 million euros in Sardinia (Italy) (source: ENAS Regional Water Authority). Currently, technological developments and environmental modelling tools are improving our ability to more effectively manage water supply systems. Models can provide decision makers with better and more timely data and information. In this …

Challenges/Advances In Distributed Watershed Modeling: A Review And Application Of The Agroecosystem-Watershed (Ages-W) Model, James C. Ascough Ii, Timothy R. Green, Olaf David, Holm Kipka, Gregory S. Mcmaster, Manfred Fink, Peter Krause, Sven Kralisch

International Congress on Environmental Modelling and Software

Progress in the understanding of physical, chemical, and biological processes influencing water quality, coupled with advances in the collection and analysis of hydrologic data, provide opportunities for significant innovations in the manner and level with which watershed-scale processes may be quantified and modeled. This paper first provides a brief review of current challenges and advances in distributed watershed modeling including quantifying and coping with the uncertainty, data availability, influence of data resolution and scaling issues, and the use of environmental modeling frameworks that help maintain model modularity, reusability, and interoperability (or compatibility). Important findings and observed trends from this work …

Linking A Modified Epic-Based Plant Growth Model (Upgm) With A Component-Based Watershed Model (Ages-W), Gregory S. Mcmaster, James C. Ascough Ii, Debora A. Edmunds, Olaf David, Larry E. Wagner, Fred A. Fox, Robert H. Erskine, Holm Kipka, Timothy R. Green

International Congress on Environmental Modelling and Software

Agricultural models and decision support systems (DSS) for assessing water use and management are increasingly being applied to diverse geographic regions at different scales. This requires models that can simulate different crops, however, very few plant growth models are available that "easily" can simulate the growth of many common and alternative crops. One option available is a suite of plant growth models based on the original plant growth model used in EPIC (Erosion Productivity Index Calculator). Various versions of the original EPIC plant growth model have been used in other agroecosystem models such as the Wind Erosion Prediction System (WEPS), …

Assessing The Transition To A Low-Carbon Economy Using Actor-Based System-Dynamic Models, Dmitry V. Kovalevsky, Klaus Hasselmann

International Congress on Environmental Modelling and Software

For a comprehensive analysis of climate mitigation policies, Integrated Assessment models (IAMs) of the coupled climate-socioeconomic system are needed. However, while there is general agreement on the physics of the climate system, the dynamics of the socioeconomic system is still the subject of considerable controversy. This has become particularly apparent since the recent global financial crisis. To explore the dynamics of the socio-economic system, a family of socio-economic models is proposed that incorporates the various alternative assumptions regarding the behaviour of the different economic actors that govern the evolution of the socio-economic system. The model family needs to be developed …

Enhancing The Policy Relevance Of Scenarios Through A Dynamic Analytical Approach, Céline Guivarch, Vanessa Schweizer, Julia Rozenberg

International Congress on Environmental Modelling and Software

We present a new dynamic analytical approach for studying scenarios produced by an integrated assessment {IA) model. Our approach involves the analysis of a large number of scenarios, which can better address three principal shortcomings of how uncertainty is traditionally handled in IA scenario studies. The shortcomings are all a result of the prevailing practice of investigating a small number of scenarios and include (1) the ad hoc nature of exploring vast socioeconomic uncertainties with only a small number of scenarios; (2) the conventional representation of alternative scenario typologies as "parallel universes• or "diverging universes•, which provide little insight on …

Development Of A Decision Support Tool To Allocate Irrigation Water On Competitive Basis: Application To Kathiraveli Village, Sri Lanka, Tom Le Cerf, Muhammed A. Bhuiyan

International Congress on Environmental Modelling and Software

This paper focuses specifically on the irrigation field and water supply tanks for ways to improve efficiency of water use and increase the resilience to climatic variability. The purpose of this paper is to develop an excel-based water balance model that will allow the maximum cropping area be planted in the upcoming agricultural season. The model consists of three modules: a crop water requirement calculator that allows the water requirements of specific crops to be compared, a water tank balance model, and a model which simulates the storage in the permanent wetland attached to the irrigation tank. The hydrological computation …

Modelling Biofilm Based Technologies With Activated Sludge Unit Processes: A Short Cut To Performance Simulation?, Noella Jones, Maebh Grace, Eoghan Clifford

International Congress on Environmental Modelling and Software

Biofilm-based passive aeration systems (PAS) have attracted recent attention as alternative, energy efficient and low maintenance technologies in the wastewater sector. However the modelling of biofilm-based PAS offers unique challenges for modellers, particularly where new technologies are not easily simulated using existing commercial modelling software. However, if the modeller is concerned only with simulating "macro" plant performance (e.g. key effluent concentrations and cycle analysis) it may be possible to efficiently model these technologies using "surrogate" unit process systems (e.g. using an activated sludge process to model a biofilm process). The pumped flow biofilm reactor (PFBR); a batch biofilm technology, is …

A Best-Worst Scaling Model Of Climate Change Abatement By Australian Farmers, Marit E. Kragt, Nikki Dumbrell, Fiona Gibson

International Congress on Environmental Modelling and Software

Storing carbon from the atmosphere in terrestrial sinks has been proposed as an important way to mitigate climate change and is a major focus in Australia's climate change policies. Mitigation by changing agricultural practices is seen as a promising way to achieve significant reductions in C02 concentrations. Several policies therefore aim to stimulate farmers to adopt so-called 'carbon farming' practices. However, there is little information about farmers' ability and willingness to adopt carbon farming. We present a best-worst scaling model to analyse farmers' decisions about adopting climate change mitigating practices. Best-worst scaling data was collected through a survey amongst mixed …

Hypothesis Testing For Management: Evolving And Answering Closed Questions Using Multiobjective Visualization, Joseph Kasprzyk, Joseph Guillaume, Joshua Kollat, Chris Danilo

International Congress on Environmental Modelling and Software

In order to use models to understand deeply uncertain future conditions, managers must be able to pose and test hypotheses about their management problems. In Iterative Closed Question Methodology (ICQM), a series of closed questions are used to structure thinking about hypotheses while looking beyond a problem's existing modeling representation. Our research is exploring how ICQM can contribute to a framework called Many Objective Robust Decision Making (MORDM), which uses multiobjective optimization and ensembles of uncertain future states of the world to create and evaluate robust solutions for environmental management. A visualization software tool; AeroVis, has greatly aided implementation of …

The Virtual Learning Commons (Vlc): Enabling Sharing And Innovation For Flexible, Responsive Solutions, Deana D. Pennington, Alida Gándara, Nick Del Rio, Omar Ochoa

International Congress on Environmental Modelling and Software

A key challenge in modeling of complex natural systems is identifying and integrating models and tools that are relevant, but were not developed for the targeted purpose. Modeling resources are proliferating, along with emerging technologies designed to enable discovery and integration of data and models. The goal of the Virtual Learning Commons (VLC) is to improve awareness and understanding of emerging methodologies and technologies, facilitate individual and group evaluation of these for innovative uses, and trace the impact of innovations across research communities. The VLC is funded by the U.S. National Science Foundation, and will be released in 2014. The …

Designing Innovative Linked Open Data And Semantic Technologies In Agro-Environmental Modelling, Rob Lokers, Stasinos Konstantopoulos, Armando Stellato, Rob Knapen, Sander Janssen

International Congress on Environmental Modelling and Software

In recent years, innovative applications exploiting Linked Open Data (LOD) and the Semantic Web have opened up, combined and cross referenced high volumes of high-quality data and created tremendous new opportunities for data users as well as data providers. However, in order to serve the broadest community of users, technologies need to be developed that can manage large, constantly updated datasets and streams that are published in formats that were not designed with cross source linking in mind.

The EU-FP7 project SemaGrow aims to tackle this challenge by developing novel algorithms and methods for querying distributed triple stores, scalable and …