Search

Abstract: Testing algorithms with real cars is a mandatory step in developing new intelligent abilities for future transportation systems. However, this step is sometimes hard to accomplish especially due to several problems. It is also difficult to reproduce the same scenario several times. Besides, some critical and/or real world forbidden scenarios cannot be tested. Thus, the comparison of several algorithms using the same experimental conditions is hard to realize. Considering that, it seems important to use simulation tools to perform scenarios with realistic conditions. The main problem with these tools is their distance from real conditions, since they deeply simplify the reality. This paper presents the architecture of the simulation/prototyping tool named Virtual Intelligent Vehicle Urban Simulator (vivus). The goal of vivus is thus to overcome the general drawbacks of classical solutions by providing the possibility of designing a vehicle virtual prototype with simulated embedded sensors and physical properties. Experiments made on linear platoon algorithms are exposed in this paper in order to illustrate the similarities between simulated results and those obtained with real cars. [Copyright &y& Elsevier]

Ns-3 simulator provides a great platform for experimental studies on different communication technologies and network topologies, and it is already used by many researchers all around the world. Unfortunately, its current TCP implementation is outdated and not ready for being used as reference platform for TCP-centered research, relegating ns-3 to play a background role in favor of its predecessor, ns-2. This paper presents the update process of ns-3 TCP module, that offers to TCP developers and researchers a consistent and RFC-compliant platform to base their works on. The method involves the addition of a new congestion-based state machine, the split of congestion control out from the socket core, and the development of a very detailed and complete testing framework, which can be easily extended. Performance tests follow the description, comparing RAM usage and execution time between ns-3 releases. Also, a case study over high-delay links on the interaction between the Transmission Control Protocol (TCP) and CoDel, an Active Queue Management algorithm born to control queuing delay, is presented. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes INSEE, a simulation framework developed at the University of the Basque Country. INSEE is designed to carry out performance-related studies of interconnection networks. It is composed of two main modules: a Functional Simulator of Interconnection Networks (FSIN) and a TRaffic GENeration module (TrGen), together with several other modules that extend INSEE’s functionality. The router models and topologies implemented in FSIN are included in this description. Likewise, the available methods to generate traffic are described thoroughly. Finally, the resource consumption of INSEE when managing different systems and workloads is also evaluated. INSEE has been used to conduct a variety of studies, including evaluation of novel topologies, diagnosis of causes of network congestion and evaluation of parallel scheduling algorithms. [ABSTRACT FROM AUTHOR]

Abstract: The most crucial aspect of distributed real-time systems is the scheduling algorithm, which must guarantee that every job in the system will meet its deadline. In this paper, we evaluate by simulation the performance of strategies for the dynamic scheduling of composite jobs in a heterogeneous distributed real-time system. Each job that arrives in the system is a directed acyclic graph of component tasks and has an end-to-end deadline. For each scheduling policy, we provide alternative versions which allow the insertion of tasks into idle time slots, using various bin packing techniques. The comparison study, based on different workloads and system heterogeneity levels, shows that the alternative versions of the algorithms outperform their respective counterparts. [ABSTRACT FROM AUTHOR]

Abstract: In this study, a mathematical model is described and developed based on a set of algebraic equations which is capable of artificially generating normal events of the electrocardiogram (ECG) such as P-wave, QRS complex, T-wave or synthetic abnormal phenomena like ST-segment episodes (i.e. depression, elevation, and sloped ascending or descending) and repolarization abnormalities such as T-wave alternans (TWA). In order to demonstrate the flexibility of the presented model for the simulation of various ECG signals, fascicular ventricular tachycardia, rate dependent conduction block, and acute Q-wave infarctions of inferior and anterior-lateral walls are simulated. Then, using the proposed artificial ECG signal, two new developed QRS detection algorithms (Modified Hilbert transform-MHT and discrete wavelet curve length-DWCL algorithms) evolved, respectively based on the implementation of some modifications to the conventional Hilbert and discrete wavelet transforms of the ECG signal, are then evaluated. To meet this end, a mathematically-simulated ECG signal with a weak R-wave is embedded into a Gaussian noise with a wide range for variances (powers) and the MHT and DWCL algorithms are applied to the resulted signal to detect QRS complexes. In the next step, an artificial baseline wander is added to the ECG signal and the performance of the MHT and DWCL algorithms in cases of high baseline wander are studied. After conducting numerous simulations, it was concluded that for the values of signal to noise ratio (SNR) larger than −5dB and amplitudes of baseline wanders approximately less than 5 times of R-wave amplitude, the two detection algorithms will have acceptable performance while it is seen that in low (negative) SNR values, performance endurance of the DWCL based detection algorithm is higher than MHT method. The Matlab m-file script of the synthetic ECG generator will be freely available from the Appendix of this paper. [Copyright &y& Elsevier]

Abstract: In this paper biomechanical interaction between osseointegrated dental implants and bone is numerically investigated through 3D linearly elastic finite-element analyses, when static functional loads occur. Influence of some mechanical and geometrical parameters on bone stress distribution is highlighted and risk indicators relevant to critical overloading of bone are introduced. Insertions both in mandibular and maxillary molar segments are analyzed, taking into account different crestal bone loss configurations. Stress-based performances of five commercially-available dental implants are evaluated, demonstrating as the optimal choice of an endosseous implant is strongly affected by a number of shape parameters as well as by anatomy and mechanical properties of the site of placement. Moreover, effectiveness of some double-implant devices is addressed. The first one is relevant to a partially edentulous arch restoration, whereas other applications regard single-tooth restorations based on non-conventional endosteal mini-implants. Starting from computer tomography images and real devices, numerical models have been generated through a parametric algorithm based on a fully 3D approach. Furthermore, effectiveness and accuracy of finite-element simulations have been validated by means of a detailed convergence analysis. [Copyright &y& Elsevier]