Dariusz Pałka

Adaptation of Social Force Model for simulation of downhill skiing

Abstract This paper describes an agent-based model of downhill skiing traffic. Our main purpose is research into skiers’ physics and behavior modeled with the use of a modified social force approach. The proposed model includes the following social forces: way-point forces – directing a skier towards consecutive way-points on the slope, skiers’ repulsion forces – keeping distance between skiers using a concept of skiers social ellipses, obstacle repulsion forces – keeping skiers away from obstacles, and slope edge repulsion – keeping a skier along the slope route using repulsion force inspired by Biot–Savart law. The proposed model also includes additional behaviors: slowing down when exceeding the skiers safe speed and braking before the end of the slope as well as a possibility of using accelerating force from ski poles. The study takes into account the whole system including ski routes and ski lifts.

Comparison of Text-Similarity Metrics for the Purpose of Identifying Identical Web Pages During Automated Web Application Testing

The paper focuses on the evaluation of effectiveness of a number of algorithms used to assess text similarity. The purpose of such evaluation is to determine the best methods for comparing and identifying near-identical web pages. Such comparison of web pages is in turn a prerequisite for building new automated testing tools and security scanners. The goal is to build scanners that will be able to automatically test the web application behavior for a large range of supplied parameters (known as fuzzing). Such testing requires massive generation and processing of requests, which in turn require fast page comparison methods. The similarity comparison is performed on a shortened, tokenized version of web pages, using a test set of pages downloaded from popular websites. A methodology for the evaluation of similarity metrics is proposed, together with a quality metric for the intended task. Several tokenization strategies are also tested and their impact on the final result is assessed.

Evolutionary Scanner of Web Application Vulnerabilities

With every passing year, there are more and more websites, which often process sensitive and/or valuable information. Due to models like Continuous Development, manual testing and code review are reduced to minimum, with new features implemented and deployed even on the same day. This calls for development of new automated testing methods, especially the ones that will allow for identification of potential security issues. In this article such a new method, which is based on automated web pages comparisons, clustering and grammatical evolution is proposed. This method allows for automated testing of a website and can identify outstanding (unusual) web pages. Such pages can then be further investigated by checking if they are legitimate, contain some unused modules or potential threats to application security. The proposed method can identify such anomalous pages within the set of interlinked web pages, but can also find web pages that are not linked to any other web page on the server by utilizing genetic-based generation of URLs.

Automatic Grammar Induction for Grammar Based Genetic Programming

This paper discusses selected aspects of evolutionary search algorithms guided by grammars, such as Grammar Guided Genetic Programming or Grammatical Evolution. The aim of the paper is to demonstrate that, when the efficiency of the search process in such environment is considered, it is not only the language defined by a grammar that is important, but also the form of the grammar plays a key role. In the most common current approach, the person who sets up the search environment provides the grammar as well. However, as demonstrated in the paper, this may lead to a sub-optimal efficiency of the search process. Because an infinite number of grammars of different forms can exist for a given language, manual construction of the grammar which makes the search process most effective is generally not possible. It seems that a desirable solution would be to have the optimal grammar generated automatically for the provided constrains. This paper presents possible solutions allowing for automatic grammar induction, which makes the search process more effective.

Active Protocol Discoverer Based on Grammatical Evolution

The paper presents a proposition of a system of protocol discovering (Protocol Discoverer) developed on the basis of Grammatical Evolution techniques. Unlike numerous other solutions based solely on observing messages between participants of a conversation, our Protocol Discoverer is an active participant which generates messages and sends them to the system for which the protocol is to be identified. This solution allows not only for identifying typical behaviors of participants within a protocol, but also for finding anomalous behaviors (the ones which normally do not occur between participants using a defined protocol).

Modeling Skiers’ Dynamics and Behaviors

The paper presents a proposal of an adaptation of our model of the skier’s dynamics and behaviors for different groups of downhill skiers: beginner, intermediate and advanced. First, we propose parametrization of our model for different groups, and next we test certain characteristics of motion for different populations of skiers. We have found that by introducing diverse populations with different behavioral patterns, we obtain a much more realistic simulation results, for instance, a more accurate distribution of skiers on ski-slopes and more realistic interactions between them.

Stereoscopic 3D Graph Visualization for Assisted Data Exploration and Discovery

Data structures and relations are becoming increasingly complex and difficult to assess and manage. Although automated rules and algorithms can be used for many data-mining tasks, there are still situations where human attention and insight is required to identify unexpected circumstances or unanticipated patterns. Presentation of large quantities of data has always been a challenging task. In this paper a method for representing large graph-based data sets is proposed to help users navigate through large clusters of data. The proposed method is based on a stereoscopic 3D visualization with special enhancements for a large multi node graph visualization. The stereoscopic projection allows for utilization of techniques that can draw users’ attention to particular regions of the graph. The method uses specially established node-node relations to calculate attention drawing factor values for each graph node.

Light-Reflection Analysis Method for 3D Surface Damage Identification

The article introduces a new high resolution 3D mesh comparison method that can be used for 3D object surface analysis. A need of 3D mesh analysis is evident in many procedures in engineering, medical or strictly graphical applications. A typical 3D object scanning process produces a high resolution 3D triangle mesh describing the surface of the object. Surface analysis based on this kind of material is usually complex or inaccurate, because each 3D mesh vertex must be identified, positioned and analyzed. A solution proposed in the paper is focused on using native 3D mesh rendering processes for mesh analysis, especially in the surface damage identification field. 3D graphical acceleration hardware and Pixel/Vertex Shaders technology will be used to prepare sets of 2D images—generated with natively 3D accelerated but specially modified light reflection rendering technique. Images then will be analyzed by comparing their 2D reflections with correct object patterns to find any damage-caused differences. The method has proven very quick to calculate and easy to apply; the test applications were programmed over a standard PC 3D accelerated graphical modules. It can also be flexibly applied, which allows for analyzing only a part of the 3D object surface if needed. Additionally, it can produce very accurate results without any precision lowering mathematical-model assumptions, commonly met and usually necessary to apply in typical 3D triangle mesh analysis.

Generating Source Code Templates on the Basis of Unit Tests

This paper describes the solution for supporting Test-driven development (TDD) methodology with the help of code analysis and generation. By automation of the creation of stub implementation, it helps to accelerate the process of passing a red phase of Red/Green/Refactor (RDR) cycle. The tool described in the paper performs a semantic analysis of the test methods defined in a subjected Java class. It uses the information gathered during a process for further generation of unit stubs. The proposed solution describes the way in which the Abstract Syntax Tree (AST) is analyzed by the statements tree decomposition. The paper also presents possible ways of preventing and resolving unit types conflicts. The tool used for stub generation of units was defined in one of the test methods implemented in a Log4J Java framework. The results obtained are compared to a real class definition, and possible ways for further extensions of the solution are suggested.

The Scrum Pricing Model for Developing a Common Software Framework in a Multi-project Environment

The article presents a new pricing model applied in Scrum contracting. The model will introduce an innovative approach to the promotion of software products with reference to their pricing—bounding non-profit features with the classical cost estimation. It will assume a principle of single charge for all components reused in products created for different customers. The model will be applicable mainly in multi-project Scrum environments, but will also support scaled multi-team Scrum development environments (where software development work is allocated to different Scrum teams). It will introduce a complete mechanism for cost estimation, with component pricing procedures (compatible with Scrum estimation methodologies), component reuse tracking and so on. The price offered for software to be developed will depend on its popularity among customers. So, the introduction of a new feature triggered by one customer can be beneficial for all parties taking part in the framework development, with justified share of the price. In such situations a common base for software development pricing techniques must be established. It will depend on different factors, such as: team effort, team velocities, resources and technologies used. To express these values a reference currency will be defined. The model, along with pricing mechanisms presented in the article, can be effectively used in many software products in which software evolution is a core. The pricing efficiency, commonly recognized as a feature of the model, will encourage potential customers to choose a software company that uses it.