22135026
A Security Based Model for Mobile Agent Software Systems
Security modeling for agents has been one of the most challenging issues in developing practical mobile agent software systems. In the past, researchers have developed mobile agent systems with emphasis either on protecting mobile agents from malicious hosts or protecting hosts from malicious agents. In this paper, we propose a security based mobile agent system architecture that provides a general solution to protecting both mobile agents and agent hosts in terms of agent communication and agent migration. We present a facilitator agent model that serves as a middleware for secure agent communication and agent migration. The facilitator agent model, as well as the mobile agent model, is based on agent-oriented G-nets — a high level Petri net formalism. To illustrate our formal modeling technique for mobile agent systems, we provide an example of agent migration to show how a design error can be detected.
15831559
An agent-based Petri net model with application to seller/buyer design in electronic commerce
Agents are becoming one of the most important topics in distributed and autonomous decentralized systems (ADS), and there are increasing attempts to use agent technologies to develop software systems in electronic commerce. Such systems are complex and there is a pressing need for system modeling techniques to support reliable, maintainable and extensible design. G-Nets are a type of Petri net defined to support modeling of a system as a set of independent and loosely-coupled modules. The authors first introduce an extension of G-Net, agent based G-Net, as a generic model for agent design. Then new communication mechanisms are introduced to support asynchronous message passing among agents. To illustrate that our formal modeling technique is effective for agent modeling in electronic commerce, a price-negotiation protocol example between buyers and sellers is provided. Finally, by analyzing an ordinary Petri net reduced from our agent based G-Net models, we conclude that our agent based G-Net models are L3-live, concurrent and effective for agent communications.
5913002
Formal modeling of synchronization methods for concurrent objects in Ada 95
One important role for Ada programming is to aid engineering of concurrent and distributed software. In a concurrent and distributed environment, objects may execute concurrently and need to be synchronized to serve a common goal. Three basic methods by which objects in a concurrent environment can be constructed and synchronized have been identified [1]. To formalize the semantics of these methods and to provide a formal model of their core behavior, we provide some graphic models based on the Petri net formalism. The purpose of this formal modeling is to illustrate the possibility of automatic program analysis for object-oriented features in Ada-95. Models for the three distributed- object synchronization methods are discussed, and a potential deadlock situation for one of the methods/models is illustrated. We conclude with some comparison of the three methods in terms of the model abstractions.
955272
A Formal Approach to Detecting Shilling Behaviors in Concurrent Online Auctions
Shilling behaviors are one of the most serious fraud problems in online auctions, which make winning bidders have to pay more than what they should pay for auctioned items. In concurrent online auctions, where multiple auctions for the same type of items are running simultaneously, shilling behaviors can be even more severe because detecting, predicting and preventing such fraudulent behaviors become very difficult. In this paper, we propose a formal approach to detecting shilling behaviors in concurrent online auctions using model checking techniques. We first develop a model template that represents two concurrent online auctions in Promela. Based on the model template, we derive an auction model that simulates the bidding processes of two concurrent auctions. Then we use the SPIN model checker to formally verify if the auction model satisfies any questionable behavioral properties that are written in LTL (Linear Temporal Logic) formulas. Thus, our approach simplifies the problem of searching for shilling behaviors in concurrent online auctions into a model checking problem. Finally, we provide a case study to illustrate how our approach can effectively detect possible shill bidders.
14915210
A Framework for Model-Based Design of Agent-Oriented Software
Agents are becoming one of the most important topics in distributed and autonomous decentralized systems, and there are increasing attempts to use agent technologies to develop large-scale commercial and industrial software systems. The complexity of such systems suggests a pressing need for system modeling techniques to support reliable, maintainable, and extensible design. G-nets are a type of Petri net defined to support system modeling in terms of a set of independent and loosely-coupled modules. In this paper, we customize the basic G-net model to define a so-called "agent-based G-net" that can serve as a generic model for agent design. Then, to progress from an agent-based design model to an agent-oriented model, new mechanisms to support inheritance modeling are introduced. To illustrate our formal modeling technique for multiagent systems, an example of an agent family in electronic commerce is provided. Finally, we demonstrate how we can use model checking to verify some key behavioral properties of our agent model. This is facilitated by the use of an existing Petri net tool.
9774737
A framework for modeling agent-oriented software
With the increasing importance of complex software systems in the software industry, the need for using agent technologies to develop large-scale commercial and industrial software systems is growing rapidly. Such systems are complex, and there is a pressing need for system modeling techniques to support reliable, maintainable and extensible design. G-nets are a type of Petri net defined to support the modeling of a system as a set of independent and loosely-coupled modules. In this paper, we first introduce an extension of G-nets - the agent-based G-net - as a generic model for agent design. Then, to progress from an agent-based design model to an agent-oriented model, new mechanisms to support inheritance modeling are introduced. To illustrate our formal modeling technique for multi-agent systems, an example of an agent family in electronic commerce is provided.
16644843
Alleviating Consumers' Privacy Concerns in Location-Based Services: A Psychological Control Perspective
Location-based services (LBS), enabled by advances in mobile and positioning technologies, have afforded users with a pervasive flexibility to be uniquely addressable and to access network and services on-the-move. However, because LBS could also associate the lifestyle habits, behaviors, and movements with a consumer’s personal identity, privacy concerns are particularly salient for LBS. Drawing on psychological control and privacy literature, we designed an experiment study to test the basic proposition that the assurance of consumers’ perceived control over their personal information has a considerable influence on alleviating their privacy concerns. Three different mechanisms of assurance of control—technology, industry self-regulation, and legislation—were manipulated in the experiment, and their effects on consumers’ privacy concerns were examined. The results indicated that the technological assurance mechanism (i.e., mobile device in this study) played the most important role in assuring consumers’ perceived control over personal information. The marriage of the privacy and psychological control literature streams provides a rich understanding of consumers’ privacy reaction to LBS usage and, therefore, benefits the privacy and human-computer interaction (HCI) research in the Information Systems discipline.
34350964
Efficient Representation of Spectral BRDFs
4864247
Data processing and compact representation of measured isotropic spectral BRDF
This paper presents the methods for both data processing and compact representation of measured isotropic spectral BRDF. For the data processing, we develop a numerical method for filtering the noises, re-sampling the data from non-uniform sampling to uniform sampling, and interpolation. For the compact representation, we propose a method to represent the spectral BRDF in both the spectral and spatial domains. In spectral domain, for each pair of the incident and outgoing directions, we represent the spectral BRDF with Fourier coefficients. In spatial domain, for all the outgoing directions of a given incident direction, we represent the same-order Fourier coefficients either directly using a linear combination of spherical harmonics or a linear combination of spherical harmonics and a Gaussian, depending on their angular dependencies. Three Gaussian expressions are presented. Numerical studies are given for a measured isotropic spectral BRDF.
10910603
Hybrid Forward Resampling and Volume Rendering
The transforming and rendering of discrete objects, such as traditional images (with or without depths) and volumes, can be considered as resampling problem – objects are reconstructed, transformed, filtered, and finally sampled on the screen grids. In resampling practices, discrete samples (pixels, voxels) can be considered either as infinitesimal sample points (simply called points) or samples of a certain size (splats). Resampling can also be done either forwards or backwards in either the source domain or the target domain. In this paper, we present a framework that features hybrid forward resampling for discrete rendering. Specifically, we apply this framework to enhance volumetric splatting. In this approach, minified voxels are taken simply as points filtered in screen space; while magnified voxels are taken as spherical splats. In addition, we develop two techniques for performing accurate and efficient perspective splatting. The first one is to efficiently compute the 2D elliptical geometry of perspectively projected splats; the second one is to achieve accurate perspective reconstruction filter. The results of our experiments demonstrate both the effectiveness of antialiasing and the efficiency of rendering using this
7143460
A system of high-dimensional, efficient, long-cycle and portable uniform random number generators
We propose a system of multiple recursive generators of modulus <i>p</i> and order <i>k</i> where all nonzero coefficients of the recurrence are equal. The advantage of this property is that a single multiplication is needed to compute the recurrence, so the generator would run faster than the general case. For <i>p</i> = 2<sup>31</sup> − 1, the most popular modulus used, we provide tables of specific parameter values yielding maximum period for recurrence of order <i>k</i> = 102 and 120. For <i>p</i> = 2<sup>31</sup> − 55719 and <i>k</i> = 1511, we have found generators with a period length approximately 10<sup>14100.5</sup>.