Real-time interpolation of streaming data

One of the key elements of real-time $C^1$-continuous cubic spline interpolation of streaming data is an estimator of the first derivative of the interpolated function that is more accurate than the ones based on finite difference schemas.Two such greedy look-ahead heuristic estimators (denoted as MinBE and MinAJ2) based on Calculus of Variations are formally defined (in closed form) together with the corresponding cubic splines they generate, and then comparatively evaluated in a series of numerical experiments involving different types of performance measures. The results presented show that the cubic Hermite splines generated by heuristic MinAJ2 significantly outperformed these based on finite difference schemas in terms of all tested performance measures (including convergence).The proposed approach is quite general. It can be directly applied to streams of univariate functional data like time-series. Multidimensional curves defined parametrically, after splitting, can be handled as well. The streaming character of the algorithm means that it can also be useful in processing data sets that are too large to fit in memory (e.g., edge computing devices, embedded time-series databases)

Simulation-Based Sailboat Trajectory Optimization using On-Board Heterogeneous Computers

A dynamic programming-based algorithm adapted to on-board heterogeneouscomputers for simulation-based trajectory optimization was studied inthe context of high-performance sailing. The algorithm can efficiently utilizeall OpenCL-capable devices, starting the computation (if necessary, in singleprecision)on a GPU and finalizing it (if necessary, in double-precision) withthe use of a CPU. The serial and parallel versions of the algorithm are presentedin detail. Possible extensions of the basic algorithm are also described. Theexperimental results show that contemporary heterogeneous on-board/mobilecomputers can be treated as micro HPC platforms. They offer high performance(the OpenCL-capable GPU was found to accelerate the optimization routine 41fold) while remaining energy and cost efficient. The simulation-based approachhas the potential to give very accurate results, as the mathematical model uponwhich the simulator is based may be as complex as required. The black-box representedperformance measure and the use of OpenCL make the presentedapproach applicable to many trajectory optimization problems

Gradient-Based Algorithms in the Brachistochrone Problem Having a Black-Box Represented Mathematical Model , Journal of Telecommunications and Information Technology, 2014, nr 1

Trajectory optimization problems with black-box represented objective functions are often solved with the use of some meta-heuristic algorithms. The aim of this paper is to show that gradient-based algorithms, when applied correctly, can be effective for such problems as well. One of the key aspects of successful application is choosing, in the search space, a basis appropriate for the problem. In an experiment to demonstrate this, three simple adaptations of gradient-based algorithms were executed in the forty-dimensional search space to solve the brachistochrone problem having a blackbox represented mathematical model. This experiment was repeated for two different bases spanning the search space. The best of the algorithms, despite its very basic implementation, needed only about 100 iterations to find very accurate solutions. 100 iterations means about 2000 objective functional evaluations (simulations). This corresponds to about 20 iterations of a typical evolutionary algorithm, e.g. ES(μ,l )

Classic and Agent-Based Evolutionary Heuristics for Shape Optimization of Rotating Discs

The article presents a metaheuristic solution for the problem of shape optimization of a rotating annular disc. Such discs are important structural components of e.g. jet engines, steam turbines or disc brakes. The design goal is to find the disc shape that would ensure its maximal carrying capacity (corresponding to the speed of rotation), which is a variational problem with the objective functional defined by L-infinity norm. Such a definition makes the problem impossible to solve using analytical methods so utilization of metaheuristics is necessary. We present different algorithms to solve the problem starting with a classic evolutionary one, followed by agent-based and hybrid agent-based memetic algorithms, which are the main focus of this paper. The reason for this is that agent-based computing systems proved to be versatile as an optimization technique being especially efficient for the problems with complex fitness functions. The obtained experimental results encourage further application of such an approach to similar engineering problems

Towards an Agent-Based Augmented Cloud, Journal of Telecommunications and Information Technology, 2012, nr 1

In the paper an agent-based framework deployed in hybrid cluster and volunteer computing environment is presented. It utilizes two concepts proposed by the authors: Augmented Cloud and Agent Platform as a Service (AgPaaS). Both concepts are discussed in the context of Cloud Computing as defined by NIST. The key idea of the presented solution is to span the cloud (i.e., computing infrastructure) beyond the data center borders by utilizing web browsers as computational workers. The feasibility of the approach was demonstrated by two prototypes: the first one was based on Java Applets and Adobe Flash, whereas the second one on Microsoft Silverlight. The prototypes were next used to perform simple experiments, mainly related to scalability issues. Selected results from the experiments are discussed in the final part of the paper

Effectiveness and safety of transvenous extraction of single- versus dual-coil implantable cardioverter-defibrillator leads at single-center experience

The available literature lacks data concerning direct comparison of the effectiveness and safety of single- versus dual-coil implantable cardioverter-defibrillator (ICD) leads transvenous extraction. Certainly, additional shocking coil in superior vena cava adds to the amount of metal in the vascular system. Adhesions developing around the superior vena cava coil add to the difficulty of extraction of ICD lead if lead removal is required. The aim of the study was to assess the effectiveness and safety of single- and dual-coil ICD leads transvenous extraction using mechanical systems. We performed transvenous lead extraction (TLE) of 197 ICD leads in 196 patients. There were 46 (23.3%) dual-coil leads removed from 46 (23.5%) patients. Cardiovascular implantable electronic device-related infection was an indication for TLE in 25.0% of patients. The following extracting techniques were used: manual direct traction, mechanical telescopic sheaths, controlled-rotation mechanical sheaths, and femoral approach. Complete ICD lead removal and complete procedural success in both groups were similar (99.3% in single-coil vs 97.8% in dual-coil, P = .41 and 99.3% in single-coil vs 97.8% in dual-coil, P = 0.41, respectively). We did not find significant difference between major and minor complication rates in both groups (2.0% in single-coil vs 4.3% in dual-coil, and 0.7% in single-coil vs 0.0% in dual-coil, P = .58, respectively). There was 1 death associated with the TLE procedure of single-coil lead

Component-Based Architecture for Systems, Services and Data Integration in Support for Criminal Analysis, Journal of Telecommunications and Information Technology, 2012, nr 1

Criminal analysis processes is based on heterogeneous data processing. To support it, analysts utilize a large set of specialized tools, however they are usually designed to solve a particular problem are often incompatible with other existing tools and systems. Therefore, to fully leverage the existing supporting tools, their technological integration is required. In this paper we present original approach for integrating systems based on the component-driven paradigm. Firstly, a problem of supporting criminal analysis is described with a strong emphasis on the heterogeneity issues. Secondly, some theoretical information about integration is depicted followed by the details of the proposed architecture. Finally, the technological assumptions are discussed and prototype integration based on proposed concept is overviewed. om the experiments are discussed in the final part of the paper

Indications for transvenous lead extraction and its procedural and early outcomes in elderly patients : a single‑center experience

Introduction Due to the prolonged survival of patients with cardiovascular implantable electronic devices, leads often need to be removed in elderly individuals. Objectives We aimed to analyze indications for transvenous lead extraction (TLE), procedure effectiveness and safety, as well as 30‑day follow‑up in younger patients (≤80 years) and octogenarians (>80 years). Patients and methods This prospective study included 667 patients who underwent TLE: 90 octogenarians (13.5%) at a mean age of 83.8 (range, 80.4–93) years and 577 younger patients (86.5%) at a mean age of 64.2 (range, 18.9–79.9) years. Results Octogenarians had a greater number of comorbidities, fewer implantable cardioverter‑defibrillators implanted, and more frequently had infection as an indication for TLE, as compared with younger patients (33.3% vs 17.1%; P <0.001). In octogenarians, 138 leads were extracted, as compared with 894 leads in younger patients. Octogenarians and younger patients had similar rates of complete lead removal (98.6% and 97.1%, respectively; P = 0.48), total procedural success (97.8% and 96%, respectively; P = 0.7), major complications (0% and 1.6%, respectively; P = 0.45), and minor complications (2.2% and 1.6%, respectively; P = 0.45). There was 1 death associated with TLE in younger patients. Non–procedure‑related deaths within 30 days after TLE were more frequent in octogenarians than in younger patients (5.6% vs 1.9%; P = 0.04). Conclusions We showed that TLE in patients older than 80 years seems to be as effective as in younger patients; however, it is associated with significantly higher non–procedure‑related 30‑day mortality

Clinical outcomes in patients after surgical and transcatheter aortic valve replacement

INTRODUCTION Transcatheter aortic valve implantation (TAVI) and minimally invasive aortic valve replacement (minithoracotomy and ministernotomy) have become a valuable alternative to conventional surgical treatment of severe aortic stenosis (AS) in high-risk patients. OBJECTIVES The aim of the study was to evaluate long-term results and complications in patients with symptomatic AS treated with TAVI, surgical aortic valve replacement (SAVR), minithoracotomy, or ministernotomy. PATIENTS AND METHODS A total of 173 patients with symptomatic AS were enrolled to the study between the years 2011 and 2013. Propensity scores were calculated for TAVI and each surgical method separately. Differences in clinical outcomes between patients treated with TAVI and those treated with surgical methods were adjusted for propensity scores using a logistic regression analysis and presented as adjusted odds ratios with 95% confidence intrervals. RESULTS A median follow-up was 583.5 days (interquartile range, 298–736 days). Before aortic valve replacement (AVR), no significant differences in ejection fraction (EF) were observed between the groups. At 1 week after AVR, mean EF values were significantly higher in patients after TAVI in comparison with the other groups (TAVI, 50.2% ±13.1%; minithoracotomy, 44.1% ±13.4%; ministernotomy, 37.8% ±12.8%; SAVR, 40.3% ±12.5%; P = 0.001). There were no differences in the longest available follow-up mortality between the analyzed groups (P = 0.8). To our best knowledge, this is the first study comparing minithoracotomy, ministernotomy, and SAVR with TAVI in terms of long-term outcomes such as the longest available follow-up mortality, left ventricular (LV) function, complications after the procedure, and conduction disturbances and arrhythmias after the procedure. CONCULSIONS Patients undergoing TAVI show more beneficial long-term outcomes in comparison with patients undergoing minithoracotomy, ministernotomy, and SAVR and do not differ in terms of the longest available follow-up mortality. TAVI seems to have a more favorable effect on LV function and an increase in EF in comparison with the surgical methods