bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evolutionary programming‐based economic dispatch for units with multiple fuel options
Authors: Jayabarathi T. , Sadasivam G. 
Published: July 2010

AbstractThis paper presents the application of evolutionary programming (EP) to economic dispatch of generators having piecewise quadratic cost functions. The proposed EP algorithm always determines the global or near global optimum without any restrictions on the shape of the cost functions. The method is applied to an example system with piecewise cost functions and the results are compared with those of the recent adaptive Hopfield neural network method. The test results prove that the EP method is simpler and more efficient for solving economic dispatch (ED) problems with multiple cost curves than many existing techniques.
Monitoring the quality of SF6 in gas insulated S witchgear using ion mobility spectrometry
Authors: Soppart O. , Baumbach J. I. , Trindade E. , Alberti S. M. , e Silva J. M. Moraes , Klockow D. , Peier D. 
Published: July 2010

AbstractDespite of the high reliability of modern gas insulated switchgear and substations, failures still occur in their long term operation. Partial discharge measurements are useful to test the reliability of the insulating system. A refined technique, however, for rapid on‐site quality control of the insulating gas inside the equipment is still missing. For this purpose, ion mobility spectrometry is proposed, that combines relatively low cost equipment and operation with high sensitivity and rapid data acquisition. A portable ion mobility spectrometer specially designed for measurements in SF6 is presented. First results obtained from on‐site measurements in a gas insulated substation are presented and compared with supporting investigations carried out in the laboratory using SF6 artificially aged in a discharge chamber. The employment of an ion mobility spectrometer for continuous on‐line control ofSF6 is proposed in order to help to reduce the costs for service and maintenance and lead to an even higher reliability of electrical power distribution.
Analysing subsynchronous resonance phenomena in the time‐ and frequency domain
Authors: Lei X. , Buchholz B. , Povh D. 
Published: July 2010

AbstractSubsynchronous resonance (SSR) is a condition that can exist in a power system, especially for long‐distance transmission systems with series compensated line. It can cause shaft fatigue and possible damage or failure of the generator involved. The analysis of the SSR phenomenon can be performed usually by using three individual analytical methods ‐frequency scanning, eigenvalue analysis in the frequency domain and transient torque analysis in the time domain. In this paper the comprehensive simulation program NETOMAC with a complete solution for analysing SSR is presented. Based on a common data set of the system concerned, both frequency and transient torque analysis can be performed, taking interactions among the spring‐mass system of the turbine‐generator units and the electrical network into consideration. Two case studies are demonstrated in the paper. The results achieved validate the functionality of the program for SSR analysis.
Electromagnetic torque of a synchronous machine during a single out‐of‐phase reclosing
Authors: Ammari A. C. , Pierrat L. 
Published: July 2010

AbstractThe adoption of single‐pole switching for a radial transmission line which connects large synchronous machines to the power system would submit these machines to repetitive mechanical stress. To evaluate the total mechanical stress, it is first necessary to determine the electromagnetic torque and to evaluate its transient maximum values at reclosing. In this paper, maximum values of the electromagnetic transient torque at single‐pole reclosing are first computed using a simplified analytical approach. The analytical results are then validated by numerical simulations and by an experimental test on a laboratory synchronous machine. It will be shown that single‐pole reclosing would be, in the worst case, as restricting as three out‐of‐phase synchronisation.
Application of clarke's transformation to the modal analysis of asymmetrical single‐circuit three‐phase line configurations
Authors: Faria J. A. Brandāo 
Published: July 2010

AbstractThis paper addresses three interrelated topics concerning the modal analysis of asymmetrical single‐circuit three‐phase transmission lines. The subject of the study is a three‐phase overhead line whose set of conductors lie on a plane arbitrarily tilted with respect to the ground surface. Varying the angle of tilt from zero to ninety degrees transforms a flat line into a vertical line configuration. The first topic discussed is the dependence of the exact modal parameters (attenuation, phase velocity, eigenvectors) on the tilt angle measuring the line asymmetry degree. The second topic deals with the well‐known Clarke transformation which can be used to successfully diagonalize ZY matrices other than those describing balanced lines. The third topic refers to the computation of approximate modal parameters for the asymmetrical tilted line, using a very simple perturbation theory approach based on the Clarke transformation. Illustrative computation results reveal that the exact and the approximate modal parameters match well, although errors tend to increase with increasing line asymmetry.
About the role of the park imaginary power on the three‐phase line voltage drop
Authors: Ferrero A. , Leva S. , Morando A. P. 
Published: July 2010

AbstractIn this paper the line voltage drop concept is investigated and extended to non‐sinusoidal conditions. The results are applied to the three‐phase configuration. In this approach the presence of harmonic and sequence components is taken into account. The formal invariance of the obtained results with respect to the original single‐phase relationships is ensured by means of the three‐phase rms concept. The Park transformation is used as well, so that the three‐phase relationships are reduced to a simpler formal single‐phase approach: the simultaneous contributions of harmonic and sequence components are unified in a single formulation. Therefore the Park imaginary power role results as a natural extension of the usual single‐phase reactive power concept.
Position‐sensorless direct‐torque‐controlled synchronous motor drive for ship propulsion
Authors: Niemelä M. , Luukko J. , Pyrhönen J. , Pyrhönen O. , Kaukonen J. 
Published: July 2010

AbstractA new concept is proposedfor position‐sensorless Direct‐Torque‐Controlled (DTC) synchronous motor drives for ship propulsion. The principles of determination of the initial rotor position at standstill or the position of a rotating rotor, the operation at zero speed and at low rotational speeds in general are described. The study introduces also a flux linkage estimate correction method for the DTC. Some of the results of the numerous experiments performed with a laboratory prototype drive are given.
Fully biodegradable polymeric micelles based on hydrophobic‐ and hydrophilic‐functionalized poly(lactide) block copolymers
Authors: Nottelet Benjamin , Di Tommaso Claudia , Mondon Karine , Gurny Robert , Möller Michael 
Published: July 2010

AbstractNovel amphiphilic diblock copolymers from a combination of hydrophobic‐functional poly(lactides) (PLAs) with hydrophilic‐functional PLAs or poly(malic acid), respectively, toward fully biodegradable materials for medical applications, such as micellar drug delivery systems, are reported for the first time. The presented PLA‐based polymeric micelles are characterized by their small size below 100 nm, low critical micellar concentrations, good in vitro stabilities at room and body temperature, and efficient incorporation capability of hydrophobic compounds, particularly with regard to potential drug substances. Moreover, the advantage of being totally degradable with different rates at different pH values, as investigated in medical cancer treatment, is demonstrated. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3244–3254, 2010
Facile syntheses, morphologies, and optical absorptions of P3HT coil‐rod‐coil triblock copolymers
Authors: Lim Herman , Huang Kuo‐Tung , Su Wei‐Fang , Chao Chi‐Yang 
Published: July 2010

AbstractHere we report syntheses, photophysical properties, and morphologies of a series of coil‐rod‐coil ABA triblock copolymers containing highly regioregular poly(3‐hexylthiophene) (P3HT) as the central rod block. A new methodology, based on the coupling reaction between living polymeric anions [polystyrene, polyisoprene, and poly(methyl methacrylate)] and aldehyde terminated P3HT, was successfully developed to synthesize the triblock copolymers with low polydispersities. This coupling reaction was effective for building blocks with a variety of molecular weights; therefore, a good variation in compositions of the triblock copolymers could be feasibly achieved. The non‐P3HT coil segments and the solvents were found to exhibit noticeable effects on morphologies of the spin‐coated thin films. Attachment of the coil segments to P3HT did not change the optical absorption of the P3HT segment as the block copolymers were dissolved in solution regardless the chemical structure and the molecular weight of the coil segment. Interestingly, different UV–vis absorption behaviors were observed for the spin‐coated thin films of the block copolymers, which closely related to their morphologies. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3311–3322, 2010
Miktoarm star copolymers via combination of RAFT arm‐first technique and aldehyde–aminooxy click reaction
Authors: Wu Zhao‐Mian , Liang Hui , Lu Jiang , Deng Wen‐Li 
Published: July 2010

AbstractA facile synthetic pathway to miktoarm star copolymers with multiple arms has been developed by combining reversible addition–fragmentation chain transfer (RAFT) arm‐first technique and aldehyde–aminooxy “click” coupling reaction. Star polystyrene (PS) with aldehyde functionalized core was initially prepared by RAFT arm‐first technique via crosslinking of the preformed linear macro‐RAFT agents using a newly designed aldehyde‐containing divinyl compound 6,6′‐(ethane‐1,2‐diylbis(oxy))bis(3‐vinylbenzaldehyde) (EVBA). It was then used as a multifunctional coupling agent for the subsequent formation of the second generation poly(ethylene glycol) (PEG) arms via the click coupling reaction between its aldehyde groups and aminooxy‐terminated PEGs. The possible formation of PS‐PEG miktoarm star copolymer with Janus‐like segregated structure in cyclohexanone was also investigated. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3323–3330, 2010
Stereoisomeric effects in thermo‐remendable polymer networks based on Diels–Alder crosslink reactions
Authors: Canadell Judit , Fischer Hartmut , De With Gijsbertus , van Benthem Rolf A. T. M. 
Published: July 2010

AbstractThis study describes the synthesis, the spectroscopic, and the thermal characterization of linear and crosslinked polymers as well as a number of corresponding model compounds, containing Diels–Alder adducts derived from furan and maleimide groups. The thermal reversibility (rDA, DA) of structurally varied model compounds, polymeric and network structures were studied by differential scanning calorimetry, where possible in combination with 1H NMR spectroscopy. It was established that the endo and exo DA stereoisomers show significantly different thermal responses: the rDA of the endo DA‐adducts typically takes place at 20–40 K lower temperatures than that of the corresponding exo DA‐adducts in all cases, with the exception of some aromatic maleimides. Although in situ isomerization was observed to a limited extent and only in some cases, this effect is not expected to influence the thermoremendability of DA‐crosslinked networks being dependent on two separate stereoisomeric rDA steps. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3456–3467, 2010
Multistimuli responsive micelles based on well‐defined amphiphilic comb poly(ether amine) (acPEA)
Authors: Di Chunfeng , Jiang Xuesong , Lui Rui , Yin Jie 
Published: July 2010

AbstractA series of well‐defined amphiphilic comb poly (ether amine)s (acPEAs) were successfully synthesized through nucleophilic addition/ring‐opening reaction of commercial available poly(propylene glycol) (PPO) diglycidyl ether and Jeffamine L100, followed by esterification of hydroxyl groups in backbone by alkyl carboxylic acid with different chain length. acPEAs are comprised of hydrophilic short PEO chains and hydrophobic alkyl chains as comb chains, which are grafted on PPO backbone alternately to form well‐defined structure. With the very low critical micelle concentration (CMC) of around 3.0 × 10−3 g/L, the obtained acPEAs can self‐assemble into stable nanomicelles, whose aggregation is responsive to temperature, pH, and ionic strength with tunable cloud point (CP). The CP of acPEAs' aqueous solution increases with the decrease of the length of graft alkyl chains, the decrease of pH value, and the decrease of ionic strength. A transition behavior in the responsive aggregation of micelles formed by acPEA8 and acPEA10 in aqueous solution, especially at low pH value (<7.0), was observed, which was also revealed by DLS results. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3468–3475, 2010
Synthesis, characterization, and aqueous self‐assembly of amphiphilic poly(ethylene oxide)‐functionalized hyperbranched fluoropolymers
Authors: Du Wenjun , Li Yali , Nyström Andreas M. , Cheng Chong , Wooley Karen L. 
Published: July 2010

AbstractComplex amphiphilic polymers were synthesized via core‐first polymerization followed by alkylation‐based grafting of poly(ethylene oxide) (PEO). Inimer 1‐(4′‐(bromomethyl)benzyloxy)‐2,3,5,6‐tetrafluoro‐4‐vinylbenzene was synthesized and subjected to atom transfer radical self‐condensing vinyl polymerization to afford hyperbranched fluoropolymer (HBFP) as the hydrophobic core component with a number‐averaged molecular weight of 29 kDa and polydispersity index of 2.1. The alkyl halide chain ends on the HBFP were allowed to undergo reaction with monomethoxy‐terminated poly(ethylene oxide) amine (PEOx‐NH2) at different grafting numbers and PEO chain lengths to afford PEO‐functionalized HBFPs [(PEOx)y‐HBFPs], with x = 15 while y = 16, 22, or 29, x = 44 while y = 16, and x = 112 while y = 16. The amphiphilic, grafted block copolymers were found to aggregate in aqueous solution to give micelles with number‐averaged diameters (Dav) of 12–28 nm, as measured by transmission electron microscopy (TEM). An increase of the PEO:HBFP ratio, by increase in either the grafting densities (y values) or the chain lengths (x values), led to decreased TEM‐measured diameters. These complex, amphiphilic (PEOx)y‐HBFPs, with tunable sizes, might find potential applications as nanoscopic biomedical devices, such as drug delivery vehicles and 19F magnetic resonance imaging agents. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3487–3496, 2010
Diffusiosmessungen an polymeren in lösung mittels tracer‐technik
Authors: Meyerhoff G. , Meier W. 
Published: July 2010

AbstractA cell for measuring coefficients of diffusion and self‐diffusion by tracer techniques is described. The cell consists of two Teflon disks and is of the rotational shearing type. The amount of polymer is minimal (about 0.1 ml. for both components). Labeled and unlabeled fractionated polymethacrylate of identical molecular weight distribution was used to determine diffusion coefficients in benzene and toluene. The classical optical measurement is impossible, for these solvents exhibit a refraction index very close to that of polymethacrylate. In acetone, where optical as well as tracer techniques are applicable, the measured diffusion coefficients of the two methods are in good agreement. Also, measurements of the self‐diffusion of polymethacrylate in toluene are reported.
Effets des Rayons Gamma sur les Poly‐2‐ et −4‐Vinylpyridmes
Authors: David C. , Verhasselt A. , Geuskens Et G. 
Published: July 2010

Abstractγ‐Irradiated poly‐2‐vinylpyridine (2‐PVP) and poly‐4‐vinylpyridine (4‐PVP) become crosslinked and partially insoluble. The G value for crosslinking has been determined for atactic (0.27) and isotactic (0.65) 2‐PVP and for atactic 4‐PVP (0.33). The results are compared with published data on polystyrene. ESR spectra of irradiated 2‐PVP and 4‐PVP suggest that a cyclohexadienyl type radical is formed, as in polystyrene. A chain reaction involving direct intramolecular hydrogen transfer is proposed to explain the experimental results.
Kinetic aspects of the copolymerization of tetrahydrofuran with propylene oxide. Part II
Authors: Baijal M. D. , Blanchard L. P. 
Published: July 2010

AbstractThe cationic copolymerization of tetrahydrofuran with propylene oxide was carried out in the presence of boron fluoride etherate, 1,2‐propanediol, and ethylene chloride, used as catalyst–cocatalyst–solvent system. Reactions were carried out in the −40 to +20°C. temperature range, at atmospheric pressure. The influence of various other parameters on the composition and structure of the copolyetherdiols obtained has been studied. Kinetic data, including energies of activation (E) and frequency factors (A) for the comonomer (THF and PO) consumptions and data on the molecular weights and the per cent yields of the copolyetherdiols obtained are reported.
Ideas on the ultrastructural organization of the cell wall components
Authors: Fengel D. 
Published: July 2010

AbstractThe wood cell wall is composed of chemically and structurally different components. The cellulose molecules are smooth long chains, able to aggregate in longitudinal direction to compact fibrils. The polyoses consist of shorter chains with side groups and branching points so that they are not able to aggregate in such a strict order as cellulose. The orientation system of the cell wall and the behavior of isolated polyoses give reason to suppose that the polyoses are not coiled forming globular particles within the cell wall. From the ontho‐genetic point of view, lignin is the last component which is incorporated into the cell wall. The different possibilities of branching resulting from the chemical characteristics of the phenylpropanone monomer enables the formation of large molecules embedding the polysaccharide elements and filling up the remaining cavities. The results of chemical and electron microscopic studies are projected into a model representing a possible ultra‐structural organization of the components within the wood cell wall.
Clinical and biochemical study of 29 Brazilian patients with metachromatic leukodystrophy
Authors: Artigalás Osvaldo , Lagranha Valeska Lizzi , Saraiva‐Pereira Maria Luiza , Burin Maira Graeff , Lourenço Charles Marques , van der Linden Hélio , Santos Mara Lúcia Ferreira , Rosemberg Sergio , Steiner Carlos Eduardo , Kok Fernando , de Souza Carolina F. Moura , Jardim Laura B. , Giugliani Roberto , Schwartz Ida Vanessa 
Published: July 2010

AbstractMetachromatic leukodystrophy (MLD) is a lysosomal disorder caused by arylsulfatase A (ARSA) deficiency. It is classified into three forms according to the age of onset of symptoms (late infantile, juvenile, and adult). We carried out a cross‐sectional and retrospective study, which aimed to determine the epidemiological, clinical, and biochemical profile of MLD patients from a national reference center for Inborn Errors of Metabolism in Brazil. Twenty‐nine patients (male, 17) agreed to participate in the study (late infantile form: 22; juvenile form: 4; adult form: 1; asymptomatic: 2). Mean ages at onset of symptoms and at biochemical diagnosis were, respectively, 19 and 39 months for late infantile form and 84.7 and 161.2 months for juvenile form. The most frequently reported first clinical symptom/sign of the disease was gait disturbance and other motor abnormalities (72.7%) for late infantile form and behavioral and cognitive alterations (50%) for juvenile form. Leukocyte ARSA activity level did not present significant correlation with the age of onset of symptoms (r = −0.09, p = 0.67). Occipital white matter and basal nuclei abnormalities were not found in patients with the late infantile MLD. Our results suggest that there is a considerable delay between the age of onset of signs and symptoms and the diagnosis of MLD in Brazil. Correlation between ARSA activity and MLD clinical form was not found. Further studies on the epidemiology and natural history of this disease with larger samples are needed, especially now when specific treatments should be available in the near future.
The role of plant–soil feedbacks and land‐use legacies in restoration of a temperate steppe in northern China
Authors: Jiang Lili , Han Xingguo , Zhang Guangming , Kardol Paul 
Published: July 2010

AbstractPlant–soil feedbacks affect plant performance and plant community dynamics; however, little is known about their role in ecological restoration. Here, we studied plant–soil feedbacks in restoration of steppe vegetation after agricultural disturbance in northern China. First, we analyzed abiotic and biotic soil properties under mono‐dominant plant patches in an old‐field restoration site and in a ‘target’ steppe site. Second, we tested plant–soil feedbacks by growing plant species from these two sites on soils from con‐ and heterospecific origin. Soil properties generally did not differ between the old‐field site and steppe site, but there were significant differences among mono‐dominant plant patches within the sites. While soil species origin (i.e., the plant species beneath which the soil was collected) affected biomass of individual plant species in the feedback experiment, species‐level plant–soil feedbacks were ‘neutral’. Soil site origin (old‐field, steppe) significantly affected biomass of old‐field and steppe species. For example, old‐field species had higher biomass in old‐field soils than in steppe soils, indicating a positive land‐use legacy. However, soil site origin effects depended on the plant species beneath which the soils were collected. The predictive value of abiotic and biotic soil properties in explaining plant biomass differed between and within groups of old‐field and steppe species. We conclude that the occurrence of positive land‐use legacies for old‐field species may retard successional replacement of old‐field species by steppe species. However, high levels of idiosyncrasy in responses of old‐field and steppe plant species to con‐ and heterospecific soils indicate interspecific variation in the extent to which soil legacies and plant–soil feedbacks control successional species replacements in Chinese steppe ecosystems.