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There is an increasing interest in steady-state analysis of electric power systems with convertors. Harmonic analysis can be performed in the frequency domain with iterative methods that are comprehensive and efficient but may present convergence problems; this drawback can be overcome by employing appropriate models of convertors. The authors present steady-state mathematical models of line commutated convertors to be included in an iterative harmonic analysis of a power system. To avoid convergence problems and to save the accuracy of the results as well as the computational efficiency, the models are developed including AC and DC frequency dependent impedances and by solving AC and DC side equations as a whole, thus keeping a closed form solution. All nonideal conditions are taken into account.

A new tool for planning reactive power compensation is presented. It is based on the capability chart of the power system, which describes the domain of allowable operation of the system in the plane of total and reactive load demand. Reliability concepts are used to describe the ability of the power system to face the load; the stochastic approach is adopted because load demand is fundamentally uncertain. Results for the AEP 14 bus test system are presented.

The synthesis and some properties of new linear polyimides obtained via hydrogen-transfer polymerization between divinyl sulfone and diimides of tetracarboxylic acids are described.

High molecular weight polyamides were prepared from fumaric acid dichloride and unsubstituted aliphatic diamines, by the interfacial polycondensation method. The influence exerted by the molar ratio of the reagents, by their concentration, by the acceptor of the acid and by the nature of the organic solvent on both yield and inherent viscosity of the polyfumaramide obtained from trimethylenediamine was studied. The polymers obtained are partially crystalline and infusible; on heating under vacuum they degrade at about 290°C. They are soluble exclusively in strong acids, such as sulphuric and trifluoroacetic acids. Hochmolekulare Polyamide wurden durch Grenzflachen-Polykondensation aus Fumarsauredichlorid und unsubstituierten aliphatischen Diaminen hergestellt. Der Einflus des Molverhaltnisses der Reaktionspartner, ihrer Konzentration, des Saure-Akzeptors und der Natur des organischen Losungsmittels auf die Ausbeute und die Viskositat der aus Trimethylendiamin erhaltenen Polyfumaramide wurde untersucht. Die erhaltenen Polymeren sind teilweise kristallin und unschmelzbar. Durch Erhitzen im Vakuum werden sie bei etwa 290°C abgebaut. Sie sind nur in starken Sauren wie Schwefelsaure oder Trifluoressigsaure loslich.

Unsaturated polyamides from methyl-fumaric (2-methyl-fumaric and 2.3-dimethyl-fumaric) acid dichlorides and diamines, i.e. 1.6-hexamethylenediamine, 1.10-decamethylenediamine, m-xylylenediamine, piperazine and trans-2.5-dimethylpiperazine were synthesized by low-temperature polycondensation. The polymer structures and properties were investigated by IR, X-ray, NMR, DSC, and TGA analyses. All polyamides were found to be soluble in several volatile organic solvents: furthermore – unlike polyamides derived from unsubstituted fumaric acid – polyamides from substituted fumaric acid derived from primary diamines showed melting or softening points. Ungesattigte Polyamide aus 2-Methyl- und 2.3-Dimethylfumarsaure-dichloriden und Diaminen, z.B. Hexamethylendiamin, 1.10-Decamethylendiamin, m-Xylylendiamin, Piperazin und trans-2.5-Dimethylpiperazin, wurden durch Tieftemperatur-Polykondensation synthetisiert. Die Struktur und die Eigenschaften der Polymeren wurden mittels IR-, Rontgenstrahlen, NMR-, DSC- und TGA-Analyse untersucht. Alle Polyamide sind in verschiedenen fluchtigen Losungsmitteln loslich. Auserdem zeigen alle Polyamide aus substituierten Fumarsauren und primaren Diaminen, im Gegensatz zu denen aus unsubstituierter Fumarsaure, Schmelz- und Erweichungspunkte.

High molecular weight unsaturated polyamides were obtained from fumaric acid dichloride and several piperazines both by interfacial and solution polycondensation. All polymers are partially crystalline and are infusible; on heating under vacuum their degradation temperatures are ranged within 350–370°C, while in air they degrade at rather lower temperatures (265–275°C). The polypiperazinefumaramides are soluble in strong acids and also in organic solvents such as formic acid, CHCI3/CH3OH and CH2Cl2/CH3OH mixtures: from these solutions tough and transparent films can be easily cast. Mittels Grenzphasen- und Losungspolykondensation wurden hochmolekulare ungesattigte Polyamide aus Fumarsaure und verschiedenen Piperazinen erhalten. Alle Polymeren sind teilweise kristallin und unschmelzbar. Beim Erhitzen im Vakuum beobachtet man Zersetzungstemperaturen zwischen 350–370°C, wahrend in Luft wesentlich niedrigere Temperaturen (265–275°C) festgestellt werden. Die Polymeren losen sich in starken Sauren und auch in organischen Losungsmitteln, wie Ameisensaure und CHCl3/CH3OH- oder CH2Cl2/CH3OH-Mischungen. Aus diesen Losungen kann man leicht zahe und transparente Filme erhalten.

Background Thrombocytosis can follow surgery and has occasionally been observed after major orthopaedic surgery. The aim of the present study was to ascertain the platelet count (PLTC) change in patients admitted to a rehabilitation unit after major joint surgery and whether deep venous thrombosis (DVT) and poor outcomes occurred in those who had thrombocytosis. Method PLTC, red blood cells (RBC), haemoglobin (Hb), fibrinogen, and D-dimers were assessed in patients on admission and at discharge after major joint surgery. Functional outcomes were ascertained using the Barthel Scale (BS), the Functional Independence Measure (FIM) and gait evaluation. Thrombocytosis was considered to have occurred when PLTC was greater than or equal to 500 × 1009/L. All subjects with thrombocytosis had ultrasonography to assess DVT occurrence. The patients were divided into “young” and “old” groups according to an age cut-off of 75 years to investigate potential age-related differences. Results Two hundred and seventy-five patients were identified and 142 (36 M and 106 F, mean age 77.2 ± 10.7) were enrolled. Seventy-six (53.5%) underwent total hip arthroplasty (THA), 40 (51.1%) underwent hip internal fixation and 26 (18.3%) subjects underwent total knee arthroplasty (TKA). The young and old groups included 60 and 82 patients, respectively. Fifty-nine (42.4%) patients had PLTC above 400 × 1009/L. Of these, 28 (20.1%) had thrombocytosis with PLTC above 500 × 1009/L, and 15 of them (10.7%) had very high values above 600 × 1009/L. Increased levels of fibrinogen and D-dimers were also detected. No subject with thrombocytosis had DVT. Outcome was not affected by PLTC. At discharge, significant improvement in all functional assessments was observed in young compared to old people; gait: 2.9 ± 0.2 vs. 2.2 ± 0.8; BS: 97 ± 6.9 vs. 70.5 ± 25.6; and FIM: 116.4 ± 10.9 vs. 83.6 ± 31.2 (p

Thanks to the increasing capability of computing systems, the development of distribution management systems for electrical distribution systems can be approached from the perspective of flexibility, expansibility and maintainability. For this purpose, new methods have been recently proposed, in which the modeling of the distribution systems as well as algorithms and computational methods have been developed with an object-oriented (OO) approach. In this paper, an extensible software environment for the development and the implementation of OO methods, aimed at distribution network applications, is presented. It is an open platform, based on timed Petri nets and on a discrete event scheduler, useful to simulate custom applications with specifically developed libraries and code. A significant example on distribution system state estimation is presented, which highlights the features of the environment

The planning for reactive power sources can be set in the same logical framework as the planning for other components of the system by describing the ability of the system to face the load demand by means of the capability chart of the system. A reliability index is defined based on the capability chart, thus giving evidence to the role played by reactive powers in determining the aforementioned ability. The plots of this index and of an economical indicator against the total amount of reactive compensation allow evaluation of the technical and economical effectiveness of the installation of reactive power sources. Various plots can be drawn, depending on the choice of the nodes at which to install the compensating devices and of their share of the total amount of compensation. In the paper, the capability chart, the definition of the reliability index, and some criteria for choosing the installation nodes and their share of total compensation are recalled; a simplified economical indicator is then adopted, and the results on a study case are presented in terms of plots of the reliability index against this indicator.

The peculiar characteristics of distribution systems require the development of specific load flow models and solving techniques. The aim of the studies presented in literature is usually to enhance computational efficiency and convergence characteristics of the algorithms. Yet, thanks to the increase of the capacity of modern computing environments, new approaches can be adopted that give preference to flexibility, extensibility and maintainability of the software rather than to computational efficiency. In the paper, the object-oriented paradigm is applied to distribution load flow. The electrical system modeling is structured in a hierarchy of classes; for each class, data and methods are defined to implement local processing of a Newton-Raphson distribution load flow algorithm decomposed into modules; information hiding guarantees modularity and flexibility. The features of a software tool implemented in an open software CAD environment are presented. Numerical applications to a test system evidence the convergence characteristics of the algorithm.

In MV distribution systems it is very important to account for the impact of Distributed Generation (DG) on the nodal voltage profile. A key issue is to guarantee adequate performance of the voltage control system acting on the On-Load Tap Changer (OLTC) of the HV/MV transformer. Referring to the case of a distribution system with the DG connected at a single node, a simple but effective OLTC control scheme is proposed to account for both load and DG variations. It keeps the classical structure of the OLTC control system, using only local measurements of voltage and current at transformer MV terminals, and avoiding data exchange with DG. To this aim, the effects of the changes of loads and of DG power injection must be distinguished and separately evaluated. The present paper focuses on the problem of estimating distributed generation and loads and proposes a specific procedure. Numerical simulations of a basic case study are presented to give evidence of the performance of the estimating procedure.

This paper presents the nonlinear design of excitation controller and power system stabilizer (PSS) aimed at ensuring transient stability and satisfactory post-fault voltage regulation following a large disturbance. The proposed design offers the possibility to select the PSS gains so as to achieve both swings damping in an assigned time interval and desired attenuation of disturbances arising from the excitation control loop. As concerns the excitation controller design it is based on the nonlinear compensation technique and ensures a quick sustainment of the regulated voltage after that the fault is cleared. Simulation results carried-out on a four-nodes power system model show the goodness of the proposed design methodology with a reference to a severe large disturbance represented by a three-phase short-circuit near the generator terminals.

The paper deals with the application of different parameter tracking techniques to the online identification of harmonic equivalent circuits in power systems. A description of the methods and a complete discussion of the implementation issues are included. Particular attention is paid to assure good parameter tracking as well as to avoid the estimator wind-up. Numerical applications referred to a simulated case study are presented to compare the different features of the tracking algorithms in response to parameter variations.

Dispersed Generation (DG) affects the operation of distribution systems; the related modeling and analyzing techniques are affected too. A novel approach to the distribution load flow problem has been recently proposed, based on the Object Oriented (OO) paradigm and including DG. In this paper, the OO modeling and algorithm are extended to account for the inclusion of ULTC transformer's voltage regulation. To validate the proposed steady-state model and to verify its assumption of stability, a detailed dynamic model is developed in Matlab/Simulink environment for a simple case study. The numerical results give evidence of the effectiveness of the proposed steady-state model which accounts for the interaction between DG and ULTC voltage regulation.

In a previous paper a DG reactive power control scheme aimed at improving the voltage profile in a smart grid has been proposed. In this paper the control scheme is recalled and validated by detailed numerical simulations. In particular, the performance is tested in presence of uncertainties of the load variations, interactions of the proposed control scheme with the control system in the primary substation and large random variability of the DG primary source. The analysis of the results and a comparison with classical DG reactive power regulation give evidence of the obtained improvements of the voltage profile.

ADDRESS (“Active Distribution networks with full integration of Demand and distributed energy RESourceS”) is a 5-year large-scale R&D project [1] launched in June 2008 and ended in May 2013, receiving funding from the European Community's Seventh Framework Program (FP7/2007-2013) under grant agreement n° 207643. This project aims to develop a comprehensive commercial and technical framework for the development of “Active Demand” and the market-based exploitation of its benefits. In ADDRESS, “Active Demand” (AD) means the active participation of domestic and small commercial consumers in the electricity markets and in the provision of services to the other electricity system participants. The paper deals with the architecture and the algorithms developed as well as the validation field test and the AD perspectives being, at least from the technical point of view, a reality for the smart grid of the (next) future.

The management of an electric industrial plant requires a control system able to guarantee a safe operation in all situations that may arise, limiting possible outage conditions. A key issue is the validation of the control structure which requires a real-time simulation of the electric power system that is fairly accurate and computationally-efficient, together with tools for data exchange that allow a reliable communication with all the control devices. In this paper, the components and the architecture of a laboratory test facility for the validation of control systems is presented, which is based on a real time digital simulator of the electric industrial plants. Specific details are given concerning the communication structure needed for data exchange between the real-time simulator and the control system. The results of validation tests are presented to show the behavior of the industrial plant in different operating conditions and to prove the validation of the control structure by means of the proposed test facility.

The inherent structure theory of networks, already applied in the literature at the fundamental frequency to a variety of planning problems, is extended to the field of power system harmonics. In the context of this theory, the harmonic admittance matrices are reformulated in terms of their eigenvalues and eigenvectors, showing that these expansions can be useful to create a framework in which the power system response to harmonic disturbances can be better understood. After the presentation of the theoretical background, some power system harmonic problems are tackled to show possible applications of this theory. Numerical experiments on a 17-busbar distribution system give evidence of the significance of application to the field of power system harmonics.

The design of a indirect self-tuning power system nodal voltage regulator using the pole-shifting technique is presented. A recursive least-squares (RLS) algorithm with variable forgetting factor and dead-zone estimates at each sampling step the parameters of an approximated discrete-time linear model describing the system dynamics from the regulation node. Based on the estimated parameters, the regulator polynomials are obtained as the solution of the Diophantine equation which imposes, according to the pole-shifting approach, closed-loop pole locations ensuring the minimization of the normalized quadratic control input. The presence of limits imposed on the control input is also taken into account. Simulations results are finally report to verify the regulator performance.

Indolent Non-follicular non-Hodgkin Lymphoma (NFo-NHL) is a group of relatively frequent lymphoproliferative diseases, nevertheless extended clinical and prognostic studies are still lacking. In 2002 the Gruppo Italiano Studio Linfomi (GISL) initiated a LL02 prospective multicenter phase II trial, with the aim to evaluate the efficacy and safety of FC combination in the first-line therapy of NFo-NHL patients younger than 70 years. Between July 2002 and September 2006, 58 adult patients (35 males and 23 females, median age 64 yrs, range 40–75) affected by NFo-NHL in active disease phase, were consecutively enrolled in 12 GISL Hematological Centres. Patients were treated with a dose of 25 mg/mq Fludarabine plus 250 mg/mq Cyclophosphamide administred intravenously daily for 3 days; each cycle was repeated every 28 days for 6 courses. During the treatment patients received oral thrimethoprim-sulphametoxazole prophylaxis. After the intermediate evaluation, 48/58 patients (82.8%) had an objective response (ORR) with a 20.7% of complete remission (CR) plus 62.1% of partial remission (PR); at the final evaluation the ORR percentage was 84.5% with a 41.4% of CR (24 pts) and 43.1% of PR (25 pts); three patients were in progressive disease (5.2%) and one in stable disease (1.7%). The median overall survival (OS) was not reached with an 88% and 84% at 12 and 24 months; the progression free survival (PFS) was 89% and 77% and the event free survival (EFS) was 81% and 66% at 12 and 24 months respectively.About the toxicity profile, the major toxicity was hematological with a 18% cases of WHO grade III or IV anemia, 40% leucopenia, 33% neutropenia and 10% piastrinopenia. The 12% of patients had an infective episode wich a 7.7% of WHO grade III–IV.In conclusion the FC chemotherapy is a useful chance for advanced untreated non follicular low-grade NHL, with an optimal ORR, CR and PFS. The crucial point of FC remains OS, that not seems to be significantly improved in comparison with fludarabine alone or with standard therapy, even though the better quality of responses; Rituximab plus FC association is growing in literature as the probably key to find a real improvement also in this aspect.

The preparation of the title compounds and preliminary results of their X-ray analysis are reported.

The reaction between bischloromethyl ether and sodium sulphide gives linear formaldehyde–thioformaldehyde copolymers, with CH2S/CH2O ratios ranging from 1 to 4, and the two new cyclic co-oligomers, 1,3,5,7,9-oxatetrathiacyclodecane and 1,3,5,7,9,11-oxapentathiacyclododecane.

Adoption of zero-tillage practices with residue retention in field crops has been introduced as an alternative soil-management technique to counteract the resource degradation and high production costs derived from intensive tillage. In this sense, the biophysical models are valuable tools to evaluate and design the most suitable soil-management technique in view of future climate variability. The aim of this study was to use the ARMOSA process-based crop model to perform an assessment of tillage (T) and no-tillage (No-T) practices of durum-wheat-cropping systems in the Campania region (South of Italy) under current and future climate scenarios. First, the model was calibrated using measurements of soil water content at different depths, leaf area index, and aboveground biomass in the T and No-T treatments during the 2013–2014 season. Then, the model was further applied in the T and No-T treatments to future climate data for 2020–2100 that was generated by the COSMO-CLM model using the RCP4.5 and 8.5 paths. Results of the calibration depicted that the model can accurately simulate the soil-crop-related variables of both soil-management treatments, and thus can be applied to identify the most appropriate conservation agricultural practices in the durum-wheat system. The simulation of soil water content at different depths resulted in small relative root mean square errors (RRMSE < 15%) and an acceptable Pearson’s correlation coefficient (r > 0.51); and the goodness-of-fit indicators for simulated LAI and AGB resulted in acceptable RRMSE (RRMSE < 28%), and high r (r > 0.84) in both soil-management treatments. Future climate simulations showed that No-T management will deliver 10% more wheat yield than the T, with an annual average 0.31% year−1increase of soil organic carbon, and an increase of 3.80% year−1for N uptake, which can diminish the N leaching. These results suggest that No-T could be implemented as a more resilient management for farming system in view of climate uncertainty and scarcity of resources. Therefore, these findings support the potential of the ARMOSA model to evaluate the soil-crop response of the durum-wheat system under different management conditions and to design appropriate soil-management practices for current and future climate predictions.

International audience

International audience