Jarosław Rudy

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• Ph.D.
• Assistant professor at Wrocław University of Science and Technology

The problem of performing software tests using Testing-as-a-Service cloud environment is considered and formulated as an~ online cluster scheduling on parallel machines with total flowtime criterion. A mathematical model is proposed. Several properties of the problem, including solution feasibility and connection to the classic scheduling on parall...

We consider an extension of Lagrangian relaxation methods for solving the total weighted tardiness scheduling problem on a single machine. First, we investigate a straightforward relaxation method and decompose it into upper and lower subproblems. For the upper subproblem we propose an alternative solving method in the form of a local search metahe...

In this paper, a Lagrangian relaxation approach to the problem of minimization of the total weighted tardiness is presented. The approach can be used both to solve the original problem as well as to obtain a high-quality lower bound for the branch-and-bound method. The problem was further decomposed into upper and lower problems. For the upper prob...

In this paper we consider a system of multiple mobile robots (MMRS) and the process of their concurrent motion in a shared two-dimensional workspace. The goal is to plan the robot movement along given fixed paths so as to minimize the completion time of all the robots while ensuring that they never collide. Thus, the considered problem combines the...

In this paper, a manufacturing process for a single-server permutation Flow Shop Scheduling Problem with sequence dependant, disjoint setups and makespan minimization is considered. The full problem is divided into two levels, and the lower level, aimed at finding an optimal order of setups for a given fixed order of jobs, is tackled. The mathemati...

In this paper, a flow shop scheduling problem with minimal and maximal machine idle time with the goal of minimizing makespan is considered. The mathematical model of the problem is presented. A generalization of the prefix sum, called the job shift scan, for computing required shifts for overlapping jobs is proposed. A work-efficient algorithm for...

In this paper, a non-permutation variant of the Flow Shop Scheduling Problem with Time Couplings and makespan minimization is considered. Time couplings are defined as machine minimum and maximum idle time allowed. The problem is inspired by the concreting process encountered in industry. The mathematical model of the problem and solution graph rep...

In this chapter a variant of the classic Non-permutation Flow Shop Scheduling Problem is considered. Time couplings for operations are introduced, determining the minimal and maximal allowed machine idle time between processing of subsequent jobs. The mathematical model of the problem and a graph representation of its solution are presented. Next,...

In this chapter we consider the classic flow shop problem of task scheduling, which is a representative problem for a larger group of problems in which the solution is represented by permutation, such as Traveling Salesman Problem, Quadratic Assignment Problem, etc. We consider the most expensive (time-consuming) part of the local search algorithms...

Due to the current challenges in computer forensics and password cracking, a single GPU is no longer sufficient. Thus, distributed password cracking platforms with dozens of GPUs become a necessity in the race against criminals. In this paper, we show a multi-GPU cracking platform build on Hashcat-based open-source distributed tool Hashtopolis for...

In this paper a modification of the parallel machines scheduling problem with machines capacity for the purpose of running software tests in a cloud environment is considered. The goal function to minimise is the sum of the makespan and the time needed to obtain the schedule. The processing times of tests are unknown, but can be estimated with the...

In this work a problem of scheduling execution of software tests in a Testing-as-a-Service (TaaS) cloud computing platform is considered. The problem is modeled as a specific case of the multi-objective online scheduling problem. The processing time of each software test is unknown during its first execution, but can be derived from its past execut...

In this paper, a prototype lifelogging system for monitoring people with cognitive disabilities and elderly people as well as a method for the automatic detection of dangerous activities are presented. The system allows for the remote monitoring of observed people via an Internet website and respects the privacy of the people by displaying their si...

In this paper a Testing-as-a-Service cloud system is considered. The problem of distributing software tests over cloud is modeled as a variation of the online scheduling problem with the goal of minimizing the average flowtime of jobs. History of over 20 million tests is used to develop statistical and empirical models of system activity. Developed...

This paper presents the results of research aimed at constructing a linear mathematical model that determines the influence of selected factors characterising construction production on the accident rate in the construction industry. A number of linear multi-factor mathematical models were developed, which were then compared with each other, and th...

The paper presents a certain version of Amdahl’s law intended for use with heterogeneous systems of parallel computation, which can be used to compare different technologies and configurations of parallel systems in a better way than a simple comparison of achieved speedups. A mathematical formulation of the law, derived from the known Amdahl’s law...

Introduction The construction industry is a very diverse area of human activity. Due to the large variety of buildings, and construction works related to their execution, and also the ever-changing conditions of construction, there are a number of factors that may affect the accident rate in the construction industry. These include factors directly...

The majority of construction works are carried out at height; these are works that carry a high risk of accident. This paper presents an analysis of dangerous events associated with scaffolding. Information about these events was obtained from online resources. The collected data not only allowed analysis of occupational accidents but also accident...

In this paper, we consider a software testing platform employing cloud computing services with homogeneous-treated machines based on real-life system. We describe the system and its characteristics. We treat the testing process as a job scheduling problem and develop a mathematical model for this problem. Then we assess the quality of the model by...

In this paper, a dynamic model of computation based on the Universal Turing Machine is proposed. This model is capable of applying runtime code modifications for 3-symbol deterministic Turing Machines at runtime and requires a decomposition of the simulated machine into parts called subtasks. The algorithm for performing runtime changes is consider...

In this paper, a cyclic permutation flow shop problem for a certain production line with uncertain data is considered. The goal is to minimize the cycle time. The uncertain elements in the system are identified and modeled as fuzzy numbers. A metaheuristic fuzzy-aware algorithm is developed and tested against 3 deterministic algorithms. The fuzzy a...

In this paper we propose a new approach, recommended for solving certain class of multi-criteria scheduling problems, with the use of cloud exploration of the solution space supported by fine-grained parallel computing. The approach allow us to approximate Pareto front more accurately than other known algorithms in competitive time. To show and che...

In this paper a multi-criteria fuel distribution problem similar to the common CVRP is considered with the real-life coordinates of gas stations obtained from a certain petrol company. The optimized criteria are the total distance of all tours and the number of tours. A certain method of solution representation, which ensures a feasible solution wa...

In this paper a multi-objective vehicle routing problem (MOVRP) with the criteria being the total distance and the utilization of the vehicle space is considered. Two methods were developed to decrease the execution time of the main part of the algorithm – the neighborhood search procedure. First method, an accelerator, is defined in order to reduc...

This paper is concerned with the study of possibility of performing changes to existing running programs with the use of the RAM and RASP models of computation. A new model of computation is defined with the capability of performing runtime changes. Theoretical properties, including time and space complexities, of the defined models are presented a...

In this paper the job shop scheduling problem with two criteria of minimizing makespan and the sum of tardiness of jobs is considered. This multi-objective problem is strongly NP-hard, as single criterion version is strongly NP-hard as well. A permutation-based representation for the job shop problem is used and a new hybrid parallel multi-agent me...

In this paper the job shop scheduling problem (JSP) with minimizing two criteria simultaneously is considered. JSP is frequently used model in real world applications of combinatorial optimization. Multi-objective job shop problems (MOJSP) were rarely studied. We implement and compare two multi-agent nature-based methods, namely ant colony optimiza...

In this paper, the problem of applying changes to software at runtime is considered. The computability theory is used in order to develop a more general and programming-language-independent model of computation with support for runtime changes. Various types of runtime changes were defined in terms of computable functions and Turing machines. The p...

New and very ecient parallel algorithm for the Fast Non-dominated Sorting of Pareto fronts is proposed. By decreasing its computational complexity, the application of the proposed method allows us to increase the speedup of the best up to now Fast and Elitist Multi-objective Genetic Algorithm (NSGA-II) more than two orders of magnitudes. Formal pro...

In era of Internet-based services and cloud computing the nature of a Web services is evolving. Instead of resource-retrieval that takes few miliseconds, the clients' requests may contain considerable amount of data and require minutes or even hours to perform all necessary computations and produce a proper response. This is also true in case of se...