Miguel Vargas Martin

Strategies for Hotlink Assignments

Consider a DAG (directed acyclic graph) G = (V, E) representing a collection V of web pages connected via links E. All web pages can be reached from a designated source page, represented by a source node s of G. Each web page carries a weight representative of the frequency with which it is visited. By adding hotlinks, at most one per page, we are interested in minimizing the expected number of steps needed to visit a selected set of web pages from the source page. For arbitrary DAGs we show that the problem is NP-complete. We also give algorithms for assigning hotlinks, as well as upper and lower bounds on the expected number of steps to reach the leaves from the source page s located at the root of a complete binary tree. Depending on the probability distribution (arbitrary, uniform, Zipf) the expected number of steps is at most c ċ n, where c is a constant less than 1. For the geometric distribution we show how to obtain a constant average number of steps.

Security Issues in VOIP Applications

Recent voice over Internet protocol (VoIP) technology is attracting more and more attention and interest in the industry. VoIP applications such as IP telephony systems involve sending voice transmissions as data packets over private or public IP networks as well as reassembled and decoded on the receiving side. Security concerns are always the major barrier that prevents many businesses from employing VoIP technologies. In this paper, we discuss various VoIP security threats and possible approaches to tackle the threats in VoIP applications

A monitoring system for detecting repeated packets with applications to computer worms

We present a monitoring system which detects repeated packets in network traffic, and has applications including detecting computer worms. It uses Bloom filters with counters. The system analyzes traffic in routers of a network. Our preliminary evaluation of the system involved traffic from our internal lab and a well known historical data set. After appropriate configuration, no false alarms are obtained under these data sets and we expect low false alarm rates are possible in many network environments. We also conduct simulations using real Internet Service Provider topologies with realistic link delays and simulated traffic. These simulations confirm that this approach can detect worms at early stages of propagation. We believe our approach, with minor adaptations, is of independent interest for use in a number of network applications which benefit from detecting repeated packets, beyond detecting worm propagation. These include detecting network anomalies such as dangerous traffic fluctuations, abusive use of certain services, and some distributed denial-of-service attacks.

3D-RadVis: Visualization of Pareto front in many-objective optimization

In many-objective optimization, visualization of true Pareto front or obtained non-dominated solutions is difficult. A proper visualization tool must be able to show the location, range, shape, and distribution of obtained non-dominated solutions. However, existing commonly used visualization tools in many-objective optimization (e.g., parallel coordinates) fail to show the shape of the Pareto front. In this paper, we propose a simple yet powerful visualization method, called 3-dimensional radial coordinate visualization (3D-RadVis). This method is capable of mapping M-dimensional objective space to a 3-dimensional radial coordinate plot while preserving the relative location of solutions, shape of the Pareto front, distribution of solutions, and convergence trend of an optimization process. Furthermore, 3D-RadVis can be used by decision-makers to visually navigate large many-objective solution sets, observe the evolution process, visualize the relative location of a solution, evaluate trade-off among objectives, and select preferred solutions. The visual effectiveness of the proposed method is demonstrated on widely used many-objective benchmark problems containing variety of Pareto fronts (linear, concave, convex, mixed, and disconnected). In addition, we demonstrated the capability of 3D-RadVis for visual progress tracking of the NSGA-III algorithm through generations. It is worthwhile to mention that a suitable visualization is a crucial prerequisite for an effective interactive optimization.

Use processes — modeling requirements based on elements of BPMN and UML Use Case Diagrams

This paper presents a new approach to gather requirements called Use Processes. The approach includes a Use Process Diagram which is based on notation elements of the OMG Business Process Modeling Notation and Use Case Diagrams of UML v1.5. We also propose a set of templates to describe the elements of the Use Process Diagram. We believe that a business process-oriented approach to gather requirements will lead in the customer and user satisfaction because it allows their participation in the requirements definition. This is very important because the main customers of the software applications are business people who are usually very comfortable in working with visualization of business processes. To prove the validity of our approach, we implemented it to develop three small object-oriented software projects in two organizations, one in a department of a bureau of the Mexican Government and two in a private enterprise that develops software.

Toward New Paradigms to Combating Internet Child Pornography

Child pornography is an increasingly visible problem in society today. Methods currently employed to combat it may be considered primitive and inefficient, and legal and technical issues can exacerbate the problem significantly. We explore the area from social and technical perspectives, and call for viable solutions based upon distributed network infrastructure mechanisms. We also outline the use of classification systems, which, using statistical analysis are appropriate in this context. Such methods for identifying offensive material are potentially attractive to law enforcement and can be accomplished with acceptable overhead in the routers of a network infrastructure. These classification systems may be of independent interests in other contexts such as homeland security

EliteNSGA-III: An improved evolutionary many-objective optimization algorithm

Evolutionary algorithms are the most studied and successful population-based algorithms for solving single- and multi-objective optimization problems. However, many studies have shown that these algorithms fail to perform well when handling many-objective (more than three objectives) problems due to the loss of selection pressure to pull the population towards the Pareto front. As a result, there has been a number of efforts towards developing evolutionary algorithms that can successfully handle many-objective optimization problems without deteriorating the effect of evolutionary operators. A reference-point based NSGA-II (NSGA-III) is one such algorithm designed to deal with many-objective problems, where the diversity of the solution is guided by a number of well-spread reference points. However, NSGA-III still has difficulty preserving elite population as new solutions are generated. In this paper, we propose an improved NSGA-III algorithm, called EliteNSGA-III to improve the diversity and accuracy of the NSGA-III algorithm. EliteNSGA-III algorithm maintains an elite population archive to preserve previously generated elite solutions that would probably be eliminated by NSGA-IIIs selection procedure. The proposed EliteNSGA-III algorithm is applied to II many-objective test problems with three to I5 objectives. Experimental results show that the proposed EliteNSGA-III algorithm outperforms the NSGA-III algorithm in terms of diversity and accuracy of the obtained solutions, especially for test problems with higher objectives.

Technology for Facilitating Humanity and Combating Social Deviations: Interdisciplinary Perspectives

This book presents socio-technical approaches to support the prevention, mitigation, and elimination of social deviations with the help of computer science and technology, providing historical backgrounds, experimental studies, and future perspectives on the use of computing tools to prevent and deal with physical, psychological and social problems that impact society as a whole--Provided by publisher.

ROAD-MAP for educational simulations and serious games

An international research team from Canada, United States, and Hong Kong developed a novel solution for creating interoperable, scalable learning objects along a gradient from single interactive objects for one learning activity to articulations of thousands of learning objects that become simulations capable of automatically assessing complex conceptual and performance competencies. We call this solution Research Oriented Adaptive Decision Modeling Architecture Platforms for Simulations - ROAD-MAP. Our acronym, ROAD-MAP, acknowledges the many pathways that can lead to developing educational simulations and serious games. Such pathways are not well-mapped at this time, especially in the context of how such simulations and games actually improve higher-order reasoning and pattern recognition. ROAD-MAP provides a generalized solution for building simulations and serious games within an evidence-based approach to design, development, and evaluation of new types of coupled research and teaching-learning-assessment environments for different discipline domains.

A frame handler module for a side-channel in mobile ad hoc networks

In this paper, we establish a hidden 802.11 wireless channel, with the masking of the channel achieved by inserting intentional errors in the Frame Check Sequence (FCS). We design a frame handler module to provide a proof-of-concept model of the side-channel using MATLAB and Simulink with Communication Toolbox. We justify using MATLAB over the other simulation tools because of its existing functions: physical layer IEEE 802.11 wireless local area networking (WLAN) standard, existing modular channel fading models, the MAC layer cyclic redundancy checksum (CRC) generator, the CRC Syndrome detector, and the capability of modifying fields in a frame. These existing functions allow for the creation of a frame handler which generates frames, according to our design, to be inserted as erroneous frames and recovers frames from normal 802.11 traffic. Herein we provide the design and details of the implementation of the channel. Our design offers the ability to introduce error detection and correction capabilities, and protection against passive monitoring defences. This simulation framework is a step towards the development of more sophisticated environments including multi-node simulations that maintain robust and reliable side-channel communication.