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2007

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Articles 1 - 30 of 494

Full-Text Articles in Computer Engineering

Odometry Correction Of A Mobile Robot Using A Range-Finding Laser, Thomas Epton Dec 2007

Odometry Correction Of A Mobile Robot Using A Range-Finding Laser, Thomas Epton

All Theses

Two methods for improving odometry using a pan-tilt range-finding laser is considered. The first method is a one-dimensional model that uses the laser with a sliding platform. The laser is used to determine how far the platform has moved along a rail. The second method is a two-dimensional model that mounts the laser to a mobile robot. In this model, the laser is used to improve the odometry of the robot. Our results show that the one-dimensional model proves our basic geometry is correct, while the two-dimensional model improves the odometry, but does not completely correct it.


Two Factor Authentication And Authorization In Ubiquitous Mobile Computing, Qing Zhu Dec 2007

Two Factor Authentication And Authorization In Ubiquitous Mobile Computing, Qing Zhu

Theses

Handheld devices, such as mobile phones, PDAs and others, have become an integrated part of our lives. They are perfectly suitable to become the first real-life platforms for mobile computing applications. A lightweight holistic authentication and authorization scheme is presented for this typical wireless scenario. It is shown that either SIM or Kerberos authentication has its limitations. A two-factor authentication method SIM-based Kerberos authentication is developed to implement the Secure Single Sign-on function with LDAP protocol realization for authorization and mobile directory services. Performance analysis and power consumption analyses for this protocol are presented as well. Our results show that ...


Kerberos Phone Secure Messenger, Nabeel Al-Saber Dec 2007

Kerberos Phone Secure Messenger, Nabeel Al-Saber

Theses

Security is becoming vital in today's open insecure Internet. While popular Internet enabled mobile devices are spreading widely, the security of such platforms is not maturely addressed. This research extends the popular Kerberos authentication protocol to run on mobile phones and builds a novel Kerberos Secure Phone Messenger (KSPM) on top of the protocol. Moreover, the Kerberos network authentication protocol provides user authentication and message privacy with the convenience of secret key cryptography. Such an advantage in mobile phones helps reduce the computational burden and power consumption if compared with public key cryptography. KSPM achieves high standards in terms ...


Retransmission Strategies For Moving Networks Over Ricean Fading Channels, Alex Ruiz Lee Dec 2007

Retransmission Strategies For Moving Networks Over Ricean Fading Channels, Alex Ruiz Lee

Theses

The problem of designing retransmission protocols based on Hybrid Automatic Repeat reQuest (HARQ) for moving networks over Ricean fading channels has been considered. The scenario of interest consists of one receiver traveling at a given speed while connected to a wireless network based on OFDM (e.g., WiMax) through several base stations located along the path. Five different retransmission protocols that combine HARQ with handover between adjacent base stations are considered. Their performance in terms of number of retransmissions per packet via numerical simulations, considering both frequency selective and nonselective channels are presented. The results obtained show the relevant advantage ...


Proactive Methods For Measurement Of Available Bandwidth And Link Capacity, Khondaker Musfakus Salehin Dec 2007

Proactive Methods For Measurement Of Available Bandwidth And Link Capacity, Khondaker Musfakus Salehin

Theses

With the continuous expansion of network infrastructure and deployment of applications sensitive to Quality-of-Service, network measurement plays a major role in both network planning and management. Accurate measurement of various network parameters, e.g., available bandwidth, link capacity, delay, packet loss and jitter, provides a positive impact for effective traffic engineering, Quality-of-Service (QoS) routing, optimization of end-to-end transport performance, and link capacity planning. For network measurement, there exists several proactive estimation tools based on either probe-gap model or probe-rate model that estimate path related attributes. Most of these tools that have been implemented can measure tight-link capacity (smallest available bandwidth ...


The Penn Discourse Treebank 2.0 Annotation Manual, Rashmi Prasad, Eleni Miltsakaki, Nikhil Dinesh, Alan Lee, Aravind Joshi, Livio Robaldo, Bonnie L. Webber Dec 2007

The Penn Discourse Treebank 2.0 Annotation Manual, Rashmi Prasad, Eleni Miltsakaki, Nikhil Dinesh, Alan Lee, Aravind Joshi, Livio Robaldo, Bonnie L. Webber

IRCS Technical Reports Series

This report contains the guidelines for the annotation of discourse relations in the Penn Discourse Treebank (http://www.seas.upenn.edu/~pdtb), PDTB. Discourse relations in the PDTB are annotated in a bottom up fashion, and capture both lexically realized relations as well as implicit relations. Guidelines in this report are provided for all aspects of the annotation, including annotation explicit discourse connectives, implicit relations, arguments of relations, senses of relations, and the attribution of relations and their arguments. The report also provides descriptions of the annotation format representation.


Operational Strategies For Continuum Manipulators, Matt Csencsits Dec 2007

Operational Strategies For Continuum Manipulators, Matt Csencsits

All Theses

We introduce a novel, intuitive user interface for continuum manipulators through the use of various joystick mappings. This user interface allows for the effective use of continuum manipulators in the lab and in the field. A novel geometric approach is developed to produce a more intuitive understanding of continuum manipulator kinematics. Using this geometric approach we derive the first closed-form solution to the inverse kinematics problem for continuum robots. Using the derived inverse kinematics to convert from workspace coordinates to configuration space coordinates we develop a potential-field path planner for continuum manipulators.


Computational Complexity Of Determining Which Statements About Causality Hold In Different Space-Time Models, Vladik Kreinovich, Olga Kosheleva Dec 2007

Computational Complexity Of Determining Which Statements About Causality Hold In Different Space-Time Models, Vladik Kreinovich, Olga Kosheleva

Departmental Technical Reports (CS)

Causality is one of the most fundamental notions of physics. It is therefore important to be able to decide which statements about causality are correct in different models of space-time. In this paper, we analyze the computational complexity of the corresponding deciding problems. In particular, we show that: for Minkowski space-time, the deciding problem is as difficult as the Tarski's decision problem for elementary geometry, while for a natural model of primordial space-time, the corresponding decision problem is of the lowest possible complexity among all possible spacetime models.


Reasons Why Mobile Telephone Conversations May Be Annoying: Considerations And Pilot Studies, Nigel Ward, Anais G. Rivera, Alejandro Vega Dec 2007

Reasons Why Mobile Telephone Conversations May Be Annoying: Considerations And Pilot Studies, Nigel Ward, Anais G. Rivera, Alejandro Vega

Departmental Technical Reports (CS)

Mobile telephone conversations in public places are often annoying to bystanders. Previous work has focused on the psychological and social causes for this, but has not examined the possible role of properties of the communication channel. In our paper "Do Bystanders and Dialog Participants Differ in Preferences for Telecommunications Channels?" (21st International Symposium on Human Factors in Telecommunication, 2008) we consider the possibility that a reason for the annoyance could be that bystander preferences differ from talker preferences, but conclude that this is in fact unlikely to be a major factor. This technical report provides supplemental information, specifically a broader ...


Sold Downstream: Free Speech, Fair Use, And Anti-Circumvention Law, R. Terry Parker Dec 2007

Sold Downstream: Free Speech, Fair Use, And Anti-Circumvention Law, R. Terry Parker

The University of New Hampshire Law Review

[Excerpt] “Here’s a hypo. Living in Asia, I purchased a shameful amount of music and movies, all legit purchases through reputable stores, HMV and Tower Records, but little of which will get reissued. I wanted to preserve my collection but software in the discs prevented me from ripping backup copies to my computer. Lacking the technological savvy to get around this software myself, I purchased and used a product to help me circumvent these controls. Discuss.

Courts agree that copying the music and movies here is infringement but that fair use may provide a defense. However, courts do not ...


Interval Computations And Interval-Related Statistical Techniques: Tools For Estimating Uncertainty Of The Results Of Data Processing And Indirect Measurements, Vladik Kreinovich Dec 2007

Interval Computations And Interval-Related Statistical Techniques: Tools For Estimating Uncertainty Of The Results Of Data Processing And Indirect Measurements, Vladik Kreinovich

Departmental Technical Reports (CS)

In many practical situations, we only know the upper bound D on the (absolute value of the) measurement error d, i.e., we only know that the measurement error is located on the interval [-D,D]. The traditional engineering approach to such situations is to assume that d is uniformly distributed on [-D,D], and to use the corresponding statistical techniques. In some situations, however, this approach underestimates the error of indirect measurements. It is therefore desirable to directly process this interval uncertainty. Such "interval computations" methods have been developed since the 1950s. In this chapter, we provide a brief ...


Evaluation Of Robocode As A Teaching Tool For Computer Programming, Arnold Hensman Dec 2007

Evaluation Of Robocode As A Teaching Tool For Computer Programming, Arnold Hensman

Conference Papers

Robocode began as an educational tool to aid in learning Java programming. It has since evolved into something of a phenomenon, as the prospect of creating simple to complex virtual tanks appears to pose an attractive challenge to both novice and expert programmers alike. What started out as a teaching tool has grown into a worldwide network of competitors, all keen to prove that their ‘bot’ stands out from the crowd. Competitions are well organised and many Robocode events are a PR dream for the computing companies that sponsor them. Without a doubt, this easy to use application has sparked ...


Computationally Efficient Mixed Pixel Decomposition Using Constrained Optimizations, Lidan Miao Dec 2007

Computationally Efficient Mixed Pixel Decomposition Using Constrained Optimizations, Lidan Miao

Doctoral Dissertations

Sensors with spatial resolution larger than targets yield mixed pixel, i.e., pixel whose measurement is a composite of different sources (endmembers). The analysis of mixed pixels demands subpixel methods to perform source separation and quantification, which is a problem of blind source separation (BSS). Although various algorithms have been proposed, several important issues remain unresolved. First, assuming the endmembers are known, the abundance estimation is commonly performed by employing a least squares criterion, which however makes the estimation sensitive to noise and outliers, and the endmembers with very similar signatures are difficult to differentiate. In addition, the nonnegative con- ...


Optimal Receiver For Space Time Spreading Across A Time Hopping Ppm Over Ultra Wideband Saleh-Valenzuela Mimo Channel, Peter Vial, Beata J. Wysocki, Tadeusz A. Wysocki Dec 2007

Optimal Receiver For Space Time Spreading Across A Time Hopping Ppm Over Ultra Wideband Saleh-Valenzuela Mimo Channel, Peter Vial, Beata J. Wysocki, Tadeusz A. Wysocki

Faculty Publications in Computer & Electronics Engineering (to 2015)

This paper outlines a technique which can use multiple transmit antennas to send more than one binary bit using the same number of transmit antennas over a single transmission. It uses Ultra Wideband orthogonal pulse position modulation to achieve this, with the receiver employing a Rake receiver and a Maximum Ratio Combiner optimal detector. This is done over a Space Time Spreading Time Hopping Ultra Wideband Pulse Position Modulation system assuming a rich multipath Saleh-Valenzuela MIMO channel model. Simulation results indicate that a significant gain can be achieved compared with other proposed schemes utilising multiple transmit antennas for Ultra Wide ...


Scalability Of Manet Routing Protocols For Heterogeneous And Homogenous Networks, Huda Al Amri, Mehran Abolhasan, Tadeusz Wysocki Dec 2007

Scalability Of Manet Routing Protocols For Heterogeneous And Homogenous Networks, Huda Al Amri, Mehran Abolhasan, Tadeusz Wysocki

Faculty Publications in Computer & Electronics Engineering (to 2015)

In Mobile Ad hoc Network (MANET), mobility, traffic and node density are main network conditions that significantly affect the performance of routing protocols. Much of the previous researches in MANET routing have focused on developing strategies, which suit one specific networking scenario. Therefore, there is no existing protocol that can work well in all different networking scenarios. This paper reviews characteristics of each different classes of routing protocols. Moreover, most of current routing protocols assume homogeneous networking conditions where all nodes have the same capabilities and resources. Although homogenous networks are easy to model and analysis, they exhibits poor scalability ...


Closed-Form Derivations Of Isi And Mui For Time-Reversed Ultra Wideband, K. Popovski, Beata J. Wysocki, Tadeusz Wysocki Dec 2007

Closed-Form Derivations Of Isi And Mui For Time-Reversed Ultra Wideband, K. Popovski, Beata J. Wysocki, Tadeusz Wysocki

Faculty Publications in Computer & Electronics Engineering (to 2015)

Through transmitter pre-filtering, a time reversed UWB system is capable if harnessing a multipath channel to achieve temporal and spatial focusing. Unfortunately, large RMS channel delay spread leads to significant intersymbol and multiuser interference. This paper presents closed-form expressions for self and multi-user interference for a UWB system utilizing a time-reversed approach. The influence of user multiplexing codes is taken to account through incorporation of a ‘separation probability’, which characterizes a family of hopping sequences. The standardized IEEE 802.15.3a channel model is applied, and the derived performances are compared with that of a simulated time hopped time-reversed UWB ...


Using Gis To Optimize The Design And Implementation Of The Rtk Reference Network In Abu Dhabi, Mustafa Abdulla Mohammed Almusawa Dec 2007

Using Gis To Optimize The Design And Implementation Of The Rtk Reference Network In Abu Dhabi, Mustafa Abdulla Mohammed Almusawa

Theses

Several challenging applications and construction works demand real-time measurements for positioning at the centimeter-level accuracy. This positioning accuracy can be obtained by using a Global Positioning System (GPS) roving unit and employing a single reference station (base-station) or through utilizing the service of multiple reference stations forming a Real-Time Kinematics (RTK) Reference Network.

The limitation of the single reference approach is that measurement errors are distance dependent and good accuracy can be only obtained when distances are less than 10 kms. In addition, this method requires a nearby Geodetic Control Point (GCP). Recently, RTK reference networks are widely established in ...


Fabric-On-A-Chip: Toward Consolidating Packet Switching Functions On Silicon, William B. Matthews Dec 2007

Fabric-On-A-Chip: Toward Consolidating Packet Switching Functions On Silicon, William B. Matthews

Doctoral Dissertations

The switching capacity of an Internet router is often dictated by the memory bandwidth required to bu¤er arriving packets. With the demand for greater capacity and improved service provisioning, inherent memory bandwidth limitations are encountered rendering input queued (IQ) switches and combined input and output queued (CIOQ) architectures more practical. Output-queued (OQ) switches, on the other hand, offer several highly desirable performance characteristics, including minimal average packet delay, controllable Quality of Service (QoS) provisioning and work-conservation under any admissible traffic conditions. However, the memory bandwidth requirements of such systems is O(NR), where N denotes the number of ports ...


Automated Genome-Wide Protein Domain Exploration, Bhanu Prasad Rekepalli Dec 2007

Automated Genome-Wide Protein Domain Exploration, Bhanu Prasad Rekepalli

Doctoral Dissertations

Exploiting the exponentially growing genomics and proteomics data requires high quality, automated analysis. Protein domain modeling is a key area of molecular biology as it unravels the mysteries of evolution, protein structures, and protein functions. A plethora of sequences exist in protein databases with incomplete domain knowledge. Hence this research explores automated bioinformatics tools for faster protein domain analysis. Automated tool chains described in this dissertation generate new protein domain models thus enabling more effective genome-wide protein domain analysis. To validate the new tool chains, the Shewanella oneidensis and Escherichia coli genomes were processed, resulting in a new peptide domain ...


Self-Certified Public Key Cryptographic Methodologies For Resource-Constrained Wireless Sensor Networks, Ortal Arazi Dec 2007

Self-Certified Public Key Cryptographic Methodologies For Resource-Constrained Wireless Sensor Networks, Ortal Arazi

Doctoral Dissertations

As sensor networks become one of the key technologies to realize ubiquitous computing, security remains a growing concern. Although a wealth of key-generation methods have been developed during the past few decades, they cannot be directly applied to sensor network environments. The resource-constrained characteristics of sensor nodes, the ad-hoc nature of their deployment, and the vulnerability of wireless media pose a need for unique solutions.

A fundamental requisite for achieving security is the ability to provide for data con…dential- ity and node authentication. However, the scarce resources of sensor networks have rendered the direct applicability of existing public key ...


Hardware-Efficient Scalable Reinforcement Learning Systems, Zhenzhen Liu Dec 2007

Hardware-Efficient Scalable Reinforcement Learning Systems, Zhenzhen Liu

Doctoral Dissertations

Reinforcement Learning (RL) is a machine learning discipline in which an agent learns by interacting with its environment. In this paradigm, the agent is required to perceive its state and take actions accordingly. Upon taking each action, a numerical reward is provided by the environment. The goal of the agent is thus to maximize the aggregate rewards it receives over time. Over the past two decades, a large variety of algorithms have been proposed to select actions in order to explore the environment and gradually construct an e¤ective strategy that maximizes the rewards. These RL techniques have been successfully ...


What Is Rcu, Fundamentally?, Paul E. Mckenney, Jonathan Walpole Dec 2007

What Is Rcu, Fundamentally?, Paul E. Mckenney, Jonathan Walpole

Computer Science Faculty Publications and Presentations

Read-copy update (RCU) is a synchronization mechanism that was added to the Linux kernel in October of 2002. RCU achieves scalability improvements by allowing reads to occur concurrently with updates. In contrast with conventional locking primitives that ensure mutual exclusion among concurrent threads regardless of whether they be readers or updaters, or with reader-writer locks that allow concurrent reads but not in the presence of updates, RCU supports concurrency between a single updater and multiple readers. RCU ensures that reads are coherent by maintaining multiple versions of objects and ensuring that they are not freed up until all pre-existing read-side ...


A Theoretical Framework For Quality-Aware Cross-Layer Optimized Wireless Multimedia Communications, Song Chi, Haohong Wang, Dalei Wu Nov 2007

A Theoretical Framework For Quality-Aware Cross-Layer Optimized Wireless Multimedia Communications, Song Chi, Haohong Wang, Dalei Wu

Faculty Publications from the Department of Electrical and Computer Engineering

Although cross-layer has been thought as one of themost effective and efficient ways formultimedia communications over wireless networks and a plethora of research has been done in this area, there is still lacking of a rigorous mathematical model to gain indepth understanding of cross-layer design tradeoffs, spanning from application layer to physical layer. As a result, many existing cross-layer designs enhance the performance of certain layers at the price of either introducing side effects to the overall system performance or violating the syntax and semantics of the layered network architecture. Therefore, lacking of a rigorous theoretical study makes existing cross-layer ...


How To Estimate, Take Into Account, And Improve Travel Time Reliability In Transportation Networks, Ruey L. Cheu, Vladik Kreinovich, Francois Modave, Gang Xiang, Tao Li, Tanja Magoc Nov 2007

How To Estimate, Take Into Account, And Improve Travel Time Reliability In Transportation Networks, Ruey L. Cheu, Vladik Kreinovich, Francois Modave, Gang Xiang, Tao Li, Tanja Magoc

Departmental Technical Reports (CS)

Many urban areas suffer from traffic congestion. Intuitively, it may seem that a road expansion (e.g., the opening of a new road) should always improve the traffic conditions. However, in reality, a new road can actually worsen traffic congestion. It is therefore extremely important that before we start a road expansion project, we first predict the effect of this project on traffic congestion.

Traditional approach to this prediction is based on the assumption that for any time of the day, we know the exact amount of traffic that needs to go from each origin city zone A to ...


Statistical Hypothesis Testing Under Interval Uncertainty: An Overview, Vladik Kreinovich, Hung T. Nguyen, Sa-Aat Niwitpong Nov 2007

Statistical Hypothesis Testing Under Interval Uncertainty: An Overview, Vladik Kreinovich, Hung T. Nguyen, Sa-Aat Niwitpong

Departmental Technical Reports (CS)

An important part of statistical data analysis is hypothesis testing. For example, we know the probability distribution of the characteristics corresponding to a certain disease, we have the values of the characteristics describing a patient, and we must make a conclusion whether this patient has this disease. Traditional hypothesis testing techniques are based on the assumption that we know the exact values of the characteristic(s) x describing a patient. In practice, the value X comes from measurements and is, thus, only known with uncertainty: X =/= x. In many practical situations, we only know the upper bound D on the ...


Propagation And Provenance Of Probabilistic And Interval Uncertainty In Cyberinfrastructure-Related Data Processing And Data Fusion, Paulo Pinheiro Da Silva, Aaron A. Velasco, Martine Ceberio, Christian Servin, Matthew G. Averill, Nicholas Ricky Del Rio, Luc Longpre, Vladik Kreinovich Nov 2007

Propagation And Provenance Of Probabilistic And Interval Uncertainty In Cyberinfrastructure-Related Data Processing And Data Fusion, Paulo Pinheiro Da Silva, Aaron A. Velasco, Martine Ceberio, Christian Servin, Matthew G. Averill, Nicholas Ricky Del Rio, Luc Longpre, Vladik Kreinovich

Departmental Technical Reports (CS)

In the past, communications were much slower than computations. As a result, researchers and practitioners collected different data into huge databases located at a single location such as NASA and US Geological Survey. At present, communications are so much faster that it is possible to keep different databases at different locations, and automatically select, transform, and collect relevant data when necessary. The corresponding cyberinfrastructure is actively used in many applications. It drastically enhances scientists' ability to discover, reuse and combine a large number of resources, e.g., data and services.

Because of this importance, it is desirable to be able ...


A Fitness Function To Find Feasible Sequences Of Method Calls For Evolutionary Testing Of Object-Oriented Programs, Myoung Yee Kim, Yoonsik Cheon Nov 2007

A Fitness Function To Find Feasible Sequences Of Method Calls For Evolutionary Testing Of Object-Oriented Programs, Myoung Yee Kim, Yoonsik Cheon

Departmental Technical Reports (CS)

In evolutionary testing of an object-oriented program, the search objective is to find a sequence of method calls that can successfully produce a test object of an interesting state. This is challenging because not all call sequences are feasible; each call of a sequence has to meet the assumption of the called method. The effectiveness of an evolutionary testing thus depends in part on the quality of the so-called fitness function that determines the degree of the fitness of a candidate solution. In this paper, we propose a new fitness function based on assertions such as method preconditions to find ...


Are There Rearrangement Hotspots In The Human Genome?, Max A. Alekseyev, Pavel A. Pevzner Nov 2007

Are There Rearrangement Hotspots In The Human Genome?, Max A. Alekseyev, Pavel A. Pevzner

Faculty Publications

In a landmark paper, Nadeau and Taylor [18] formulated the random breakage model (RBM) of chromosome evolution that postulates that there are no rearrangement hotspots in the human genome. In the next two decades, numerous studies with progressively increasing levels of resolution made RBM the de facto theory of chromosome evolution. Despite the fact that RBM had prophetic prediction power, it was recently refuted by Pevzner and Tesler [4], who introduced the fragile breakage model (FBM), postulating that the human genome is a mosaic of solid regions (with low propensity for rearrangements) and fragile regions (rearrangement hotspots). However, the rebuttal ...


Computing Population Variance And Entropy Under Interval Uncertainty: Linear-Time Algorithms, Gang Xiang, Martine Ceberio, Vladik Kreinovich Nov 2007

Computing Population Variance And Entropy Under Interval Uncertainty: Linear-Time Algorithms, Gang Xiang, Martine Ceberio, Vladik Kreinovich

Departmental Technical Reports (CS)

In statistical analysis of measurement results, it is often necessary to compute the range [V-,V+] of the population variance V=((x1-E)^2+...+(xn-E)^2)/n (where E=(x1+...+xn)/n) when we only know the intervals [Xi-Di,Xi+Di] of possible values of the xi. While V- can be computed efficiently, the problem of computing V+ is, in general, NP-hard. In our previous paper "Population Variance under Interval Uncertainty: A New Algorithm" (Reliable Computing, 2006, Vol. 12, No. 4, pp. 273-280), we showed that in a practically important case, we can use constraints techniques to compute V+ in time ...


Optical Reading And Playing Of Sound Signals From Vinyl Records, Arnold Hensman, Kevin Casey Oct 2007

Optical Reading And Playing Of Sound Signals From Vinyl Records, Arnold Hensman, Kevin Casey

Conference Papers

While advanced digital music systems such as compact disk players and MP3 have become the standard in sound reproduction technology, critics claim that conversion to digital often results in a loss of sound quality and richness. For this reason, vinyl records remain the medium of choice for many audiophiles involved in specialist areas. The waveform cut into a vinyl record is an exact replica of the analogue version from the original source. However, while some perceive this media as reproducing a more authentic quality then its digital counterpart, there is an absence a safe playback system. Contact with the stylus ...