ROOT is an object-oriented C++ framework conceived in the high-energy physics (HEP) community, designed for storing and analyzing petabytes of data in an efficient way. Any instance of a C++ class can be stored into a ROOT file in a machine-independent compressed binary format. In ROOT the TTree object container is optimized for statistical data analysis over very large data sets by using vertical data storage techniques. These containers can span a large number of files on local disks, the web, or a number of different shared file systems. In order to analyze this data, the user can chose out of a wide set of mathematical and statistical functions, including linear algebra classes, numerical algorithms such as integration and minimization, and various methods for performing regression analysis (fitting). In particular, the RooFit package allows the user to perform complex data modeling and fitting while the RooStats library provides abstractions and implementations for advanced statistical tools. Multivariate classification methods based on machine learning techniques are available via the TMVA package. A central piece in these analysis tools are the histogram classes which provide binning of one-and multi-dimensional data. Results can be saved in high-quality graphical formats like Postscript and PDF or in bitmap formats like JPG or GIF. The result can also be stored into ROOT macros that allow a full recreation and rework of the graphics. Users typically create their analysis macros step by step, making use of the interactive C++ interpreter CINT, while running over small data samples. Once the development is finished, they can run these macros at full compiled speed over large data sets, using onthe-fly compilation, or by creating a stand-alone batch program. Finally, if processing farms are available, the user can reduce the execution time of intrinsically parallel tasks -e.g. data mining in HEP -by using PROOF, which will take care of optimally distributing the work over the available resources in a transparent way. Antcheva et al. / Computer Physics Communications 180 (2009) [2499][2500][2501][2502][2503][2504][2505][2506][2507][2508][2509][2510][2511][2512] Program summary

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Three-phase voltage outages compensator with cascaded multilevel converterThe paper presents a laboratory prototype of the three-phase transformerless voltage outages compensator with an energy storage based on high voltage supercapacitors. The system described is able to protect an isolated grid e.g. in industry against short voltage interruptions, dips and sags. An idea of a control method as well as a digital controller has been presented, too.

The paper proposes a general description system of the five-phase two-level inverter. The two base methods are presented and discussed. The first one is based on the standard space vector transformation, while the other uses state vectors which enable the definition of the basic physical quantities of the inverter: current and voltage. The proposed notation system offers a general simplification of vector identification. It comprises a standardized proposal of notation and vector marking, which may be extremely useful for the specification of inverter states. The described notation system makes it possible to reach correlation between state and space vectors. It presents space and state vectors using the same digits. These properties suggest that the proposed notation system is a useful mathematical tool and may be really suitable in designing control algorithms. This mathematical tool was verified during simulation tests performed with the use of the Simulation Platform for Power Electronics Systems—PLECS.

The paper is related to the problem of generating the high quality AC voltage waveforms using multilevel converters. This technique can be applied especially in the distributed power energy systems with renewable DC voltage sources like photovoltaic farms and fuel cells. A novel approach to the synthesis of AC voltage waveforms, considering minimising of THD by use of analytical methods like Fourier transform is presented. The analysis of the obtained waveforms is presented as well as examples of chosen parameter optimisation. The meaning of the THD factor from the construction point of view is analysed and a new bandwidth factor THD B , containing more information about the frequency range of harmonic components is proposed in the paper.