Coarse-Grained, Fine-Grained, and Lock-Free Concurrency Approaches for Self-Balancing B-Tree

This dissertation examines the concurrency approaches for a standard, unmodified B-Tree which is one of the more complex data structures. This includes the coarse grained, fine-grained locking, and the lock-free approaches. The basic industry standard coarse-grained approach is used as a base-line for comparison to the more advanced fine-grained and lock-free approaches. The fine-grained approach is explored and algorithms are presented for the fine-grained B-Tree insertion and deletion. The lock-free approach is addressed and an algorithm for a lock-free B- Tree insertion is provided. The issues associated with a lock-free deletion are discussed. Comparison trade-offs are presented and discussed. As a final part of this effort, specific testing processes are discussed and presented

Simulating use cases for the UAH autonomous electric car

2019 IEEE Intelligent Transportation Systems Conference (ITSC), Auckland, New Zealand, 27-30 Oct. 2019This paper presents the simulation use cases for the UAH Autonomous Electric Car, related with typical driving scenarios in urban environments, focusing on the use of hierarchical interpreted binary Petri nets in order to implement the decision making framework of an autonomous electric vehicle. First, we describe our proposal of autonomous system architecture, which is based on the open source Robot Operating System (ROS) framework that allows the fusion of multiple sensors and the real-time processing and communication of multiple processes in different embedded processors. Then, the paper focuses on the study of some of the most interesting driving scenarios such as: stop, pedestrian crossing, Adaptive Cruise Control (ACC) and overtaking, illustrating both the executive module that carries out each behaviour based on Petri nets and the trajectory and linear velocity that allows to quantify the accuracy and robustness of the architecture proposal for environment perception, navigation and planning on a university Campus.Ministerio de Economía y CompetitividadComunidad de Madri

Concurrent Access Algorithms for Different Data Structures: A Research Review

Algorithms for concurrent data structure have gained attention in recent years as multi-core processors have become ubiquitous. Several features of shared-memory multiprocessors make concurrent data structures significantly more difficult to design and to verify as correct than their sequential counterparts. The primary source of this additional difficulty is concurrency. This paper provides an overview of the some concurrent access algorithms for different data structures

Elements of concurrent programming (Third edition)

These lecture notes are intended to introduce the reader to the basic notions of nondeterministic and concurrent programming. We start by giving the operational semantics of a simple deterministic language and the operational semantics of a simple nondeterministic language based on guarded commands. Then we consider concurrent computations based on: (i) vectorization, (ii) shared variables, and (iii) handshaking communications à la CCS (Calculus for Communicating Systems) [16]. We also address the problem of mutual exclusion and for its solution we analyze various techniques such as those based on semaphores, critical regions, conditional critical regions, and monitors. Finally, we study the problem of detecting distributed termination and the problem of the serializability of database transactions. Sections 1, 2, and 6 are based on [16,22]. The material of Sections 3 and 4 is derived from [1,2,4,5,7,8,13,18,20]. Section 5 is based on [10] and is devoted to programming examples written in Java where the reader may see in action some of the basic techniques described in these lecture notes. In Section 7 we closely follow [3]. We would like to thank Dr. Maurizio Proietti for his many suggestions and his encouragement, Prof. Robin Milner and Prof. Matthew Hennessy for introducing me to CCS, Prof. Vijay K. Garg from whose book [10] I learnt concurrent programming in Java, my colleagues at Roma Tor Vergata University for their support and friendship, and my students for their patience and help. Many thanks also to Dr. Gioacchino Onorati and Lorenzo Costantini of the Aracne Publishing Company for their kind and helpful cooperation. Roma, April 2005 In the third edition we have corrected a few mistakes, we have improved Chapter 2, and we have added in the Appendix a Java program for the distributed computation of spanning trees of undirected graphs. Thanks to Dr. Emanuele De Angelis for discovering an error in the presentation of Peterson’s algorithm. Roma, January 200

The key node method: a highly-parallel alpha-beta algorithm

Journal ArticleA new parallel formulation of the alpha-beta algorithm for minimax game tree searching is presented. Its chief characteristic is incremental information sharing among subsearch processes in the form of "provisional" node value communication. Such "eager" communication can offer the double benefit of faster search focusing and enhanced parallelism. This effect is particularly advantageous in the prevalent case when static value correlation exists among adjacent nodes. A message-passing formulation of this idea, termed the "Key Node Method", is outlined. Preliminary experimental results for this method are reported, supporting its validity and potential for increased speedup

Data Fusion Methods and Algorithms in the Context of Autonomous Systems - A path planning algorithms analysis and optimization exploiting fused data

L'abstract è presente nell'allegato / the abstract is in the attachmen