bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel Real-Time Stability Assessment Algorithm Based on Synchro-Phasors Measurement and Parallel Algorithms for Multi-Machine Networks.
Authors: Ali Mohamed Abdelwahhab , Mansour Wagdy Mohamed , Anis Wael Refaat , Bendary Fahmy Metwally 
Published: September 2012

Abstract
The introduction of wide area measurements has brought a need for real time assessment methods of power systems, which are accurate and fast. The time varying coefficients in synchronous machine equations make it difficult to find solutions to obtain machine voltages, currents and flux linkages when expressed in phase quantities under transient conditions. The paper presents an approach to design power system transient stability assessment using direct methods for a multi-machine network based on multiple synchronized phasors, measured from Phasor Measurement Units (PMUs) and generator parameters. The generator rotor angle was derived from phasor measurements of voltage and current, and generator parameters using direct algorithm . The method assumes that a temporary fault is applied to the system therefore the pre-fault and post-fault conditions are similar. The multi-machine system was reduced to groups denoted Single Machine to Equivalent Bus (SMEB) models and another groups denoted Load Equivalent Bus (LEB) using Parallel Algorithms (PAs) [1]. The use of these PAs eliminates the SPMUs at each bus in the system, and it is required number of SPMUs only equals the number of generator buses. So that, the Equal Area Criterion in both rotor angle domain and time domain can be applicable for the SMEBs groups to assess the system stability in real-time through the Synchro-Phasors Measurements Units (SPMUs). A temporary three phase fault was simulated at test system comprises 2-machine, 8-bus network for validating the novel algorithm.
Integrated Kalman-Independent Component Analysis Method for Harmonic Current Estimation on an Interconnected Four Bus Simulated and Laboratory Model
Authors: Supriya P. , Nambiar P. 
Published: September 2012

Abstract
Wide use of non-linear loads results in harmonic propagation throughout the entire power system. The harmonics generated in the power system by the harmonic injection buses need to be properly measured and quantified using minimal information about the power system network. Independent Component Analysis (ICA) provides several algorithms for harmonic state estimation, some of which are more accurate at specific harmonic frequencies. In this paper, the best ICA algorithm for steady state performance (i.e. the algorithm with the least error) is chosen and the resulting mixing matrix is processed by a Kalman Filter which functions as an optimal estimator. The harmonic state estimation is implemented on a simulated four bus system and a laboratory four bus model is also wired and the results of the work are presented.
Identification of Fault Location in Distribution Networks Using Multi Class Support Vector Machines
Authors: Agrawal Rimjhim , Dhadbanjan Thukaram 
Published: September 2012

Abstract
This paper presents a multi-class support vector machine (SVMs) approach for locating and diagnosing faults in electric power distribution feeders. Different from the traditional Fault Section Estimation methods, the proposed approach uses measurements available at the substation and remote terminal units (RTUs). To show the effectiveness of the proposed methodology, a practical 52 nodes, 3 feeder distribution systems (DS) with loads is considered. Practical situations in distribution systems, such as protective devices (circuit breakers/isolators) placed at different locations and all types of faults with a wide range of varying source short circuit (SSC) levels and fault impedances are considered for studies. The proposed fault location scheme is capable of accurately identify the fault type, location of faulted feeder section and the fault impedance. The results demonstrate the feasibility of applying the proposed method in practical distribution automation (DA) system for fault diagnosis.
Optimization of Microwave Assisted Extraction Conditions for Total Flavonoids in Toona Sinensis Leaves Using Response Surface Methodology
Authors: Wang Changlu , Li Zhenjing , Li Fengjuan , Chen Mianhua , Wang Yurong , Li Yadi , He Dong 
Published: September 2012

Abstract
In this study Microwave assisted extraction (MAE) was employed to extract total flavonoids (TF) from the Toona sinensis leaves (TSL). Single factor experiments to evaluate the effects of the process parameters (extraction duration, solvent-solid ratio, ethanol volume fraction, and extraction times) on TF yield of TSL was performed, and response surface methodology (RSM) were used to optimize the extraction parameters. The analysis of variance indicated that the linear coefficients extraction duration, the quadratic terms of extraction duration and solvent-solid ratio, had highly significant effects on the TF yield (P<0.01). And, the quadratic terms of ethanol volume fraction had significant effects on the TF yield (P<0.05). The optimal conditions to obtain the maximum TF yield from TSL were extraction duration 85s, solvent-solid ratio (v/w, mL/g) 20, ethanol volume fraction 50%, microwave power 700 W, and repeated extraction two times. Under these optimal conditions, the TF yield was up to 2.39%. The analysis of variance (ANOVA) and validation test indicated that the method is useful and reliable.
Thermal Properties of Polyurethane Films Prepared from Mixed Cellulose, Hemicelluloses and Lignin
Authors: Shao Meng , Liu Zhu-qing , Li Dong , Zhao Yang , Özkan Necati , Chen Xiao Dong 
Published: September 2012

Abstract
Polyurethane (PU) films were prepared from liquefied cellulose, hemicelluloses and lignin in different proportions. The simplex-lattice design method was employed to investigate the effects of each component and their associated interactive effects on the properties of the liquefied products and the PU films. Thermal properties were studied by means of Dynamic Mechanical Analyzer (DMA) and Thermal Gravimetry Analyzer (TGA). Results showed that the contents of cellulose, hemicelluloses and lignin significantly affected the thermal properties of PU films. The results of DMA suggested that the addition of the liquefied materials increased the glass transition temperature (Tg) of polyurethane (PU) films but decreased both storage modulus (E') and loss modulus (E''). TGA results indicated that the addition of the liquefied materials decreased the thermal stabilities of the PU films.
A characterization of multiple (n – k)-blocking sets in projective spaces of square order
Authors: Ferret S. , Storme L. , Sziklai P. , Weiner Zs. 
Published: September 2012

Abstract
In [10], it was shown that small t-fold (n - k)-blocking sets in PG(n; q), q = ph, p prime, h ≥ 1, intersect every k-dimensional space in t (mod p) points. We characterize in this article all t-fold (n - k)-blocking sets in PG(n,q), q square, q ≥ 661, t<cp q1/6 /2 |B|<tqn-k +2tqn-k-1 √q intersecting every k-dimensional space in t (mod √q ) points.
Metal-dielectric composite optical coatings: underlying physics, main models, characterization, design and application aspects
Authors: Stenzel Olaf , Macleod Angus 
Published: September 2012

Abstract
Metal island films are a matter of research in different branches of applied physics and technology. One possible future application field is their use as a substantial part of optical interference coatings, forming metal-dielectric composite multilayer coatings. This tutorial provides background on optical specifics of metal island films and ideas how these specifics could be exploited in coating technology. Consideration is given to effective optical constants of copper and silver island films, characterization methods and design strategies pursuing neutral density filters, asymmetric beamsplitters and decorative coating specifications.
Review of computational lithography modeling: focusing on extending optical lithography and design-technology co-optimization
Authors: Lai Kafai 
Published: September 2012

Abstract
Advances in computational lithography over the last 10 years have been instrumental to the continued scaling of semiconductor devices. Competitive scaling requires two types of complementary models: fast predictive empirical models that can be used for pattern correction and verification; rigorous physical models that can be used to identify key physical effects that must be considered to ensure pattern fidelity, but are too resource intensive to use for full chip applications. Today, all computational lithography efforts such as the optical proximity correction (OPC) and the optical rules check (ORC) depend on the ability to predictively model the lithography and metrology processes. We discuss some of the current modeling practices in optics, mask, resist and etching, leading to the “Holy Grail” of predictively modeling entire patterning process which we call “virtual fab”. Extreme ultraviolet (EUV) modeling is discussed due to its potential to extend optical lithography scaling for future nodes. Modeling of novel technologies such as Diblock Copolymer patterning is also discussed to demonstrate new opportunities for continued scaling. Complexity of the “virtual fab” approach is extremely high as there are multiple dimensions in this approach. The need to overcome this complexity, by reducing the number of dimensions of the problem, is evident. Lastly, the ability to leverage lithography modeling in design co-optimization is an important element of semiconductor device scaling.
From transcription to translation: new insights in the structure and function of Argonaute protein
Authors: Giorgi Corinna , Cogoni Carlo , Catalanotto Caterina 
Published: September 2012

AbstractArgonaute proteins play a central role in gene silencing pathways mediated by small RNA molecules. The ancestral function of small RNA-dependent silencing is related to genome protection against parasitic nucleic acids, such as transposons and viruses. However, new classes of small RNAs are continuously being uncovered in all higher eukaryotes in which they play important functions in processes ranging from embryonic development to differentiation to cell proliferation and metabolism. Small RNAs have variegated biogenesis pathways and accomplish distinct functions. Nevertheless, it appears that all small RNAs work merely as guides in recognizing the target RNAs invariably relying on the interaction with Argonaute proteins and associated factors for their biological function. Here, we discuss recent findings on the structure and regulation of mammalian Argonaute proteins and overview the various roles that these versatile proteins play in regulating gene expression.
Hormone-autonomous cell culture from cotydelonary tissue of the marine plant Cymodocea nodosa
Authors: Elso Maite Zarranz , González-Henríquez Nieves , García-Jiménez Pilar , Robaina Rafael R. 
Published: September 2012

Abstract

In vitro germinated seedlings of ­Cymodocea nodosa were used as a source of young embryonic tissue for cell culture. Histological study of the cotyledon revealed the presence of meristematic tissue that gave rise to the first leaf of the plantlet, which released large numbers of cells after enzymatic digestion and thus indicated great growth potential. An effective enzymatic digestion protocol for C. nodosa meristem tissue was developed; this consisted of a 24-h digestion period at 28°C using a 0.6-m enzymatic solution (plasmolysis medium containing 1% (w:v) cellulase and hemicellulase). It was necessary to add citric acid (0.02 m) as an antioxidant to the enzymatic solution to obtain the highest cell yield and viability (mean±SE: 371.6±30.1×105 cells g-1 fw and 97.8±0.6%, respectively). NaCl and other salt components of the seawater were key factors in the establishment of axenic cell cultures and their further progress; their absence in the medium inhibited contaminant overgrowth. Nevertheless, cells maintained growth for 90 days, even without hormones and deprived of salts, although these salts might be necessary to allow the development of morphogenetic programmes desired for plant production. In this manner, we generated a basic tool for the future of C. nodosa in vitro culture that will allow the establishment and maintenance of hormone-autonomous cell cultures with strong potential in future biotechnology for marine higher plants.
An efficient synthesis of 2-substituted benzoxazoles using cerium(III) chloride/sodium iodide as catalyst
Authors: Zhu Xun , Wei Yunyang 
Published: September 2012

Abstract
An efficient and environmentally benign method for the synthesis of 2-substituted benzoxazoles is reported. The condensation of 2-aminophenol with an aldehyde gave an imine intermediate, which was cyclized and dehydrogenated to 2-substituted benzoxazole with good yield in the presence of CeCl3/NaI as catalyst. The one-pot synthesis was carried out in toluene at 100°C using O2 as the oxidant.
Synthesis of perhydro-N-(2,2-disubstituted-3-aminopropyl) heterocycles as potentially bioactive compounds and fragments for combinatorial chemistry
Authors: Hayotsyan Sargis S. , Mkryan Gevorg G. , Aghekyan Asya A. , Melikyan Gagik S. 
Published: September 2012

Abstract
A new method for the preparation of perhydro-­N-(2,2-disubstituted-3-aminopropyl) heterocycles that allows to obtain a large variety of corresponding derivatives with high to moderate yields using simple procedures is described.
Enzymatic bleaching of eucalyptus kraft pulp: effects on the prebleaching filtrate, pulp quality and paper properties
Authors: Borges Maria Tereza , Silva Claudio Mudado , Colodette Jorge Luiz , de Oliveira Rubens Chaves , Tesser Flavio 
Published: September 2012

Abstract
Enzymatic bleaching appears to be a promising approach for clean bleaching processes and the reduction of bleaching chemical consumption. In this work, the quality of the filtrates and the pulps has been characterized after enzymatic prebleaching stages of eucalyptus kraft pulp. Four different conditions with xylanase were investigated. Following each prebleaching stage, the properties of the pulp [kappa number, brightness, content of hexenuronic acid (HexA), xylan removal, and pulp yield lost], and of the resulting effluents (chemical oxygen demand (COD), biochemical oxygen demand (BOD), color, and conductivity) were determined. In addition, a complete bleaching sequence was performed to characterize the pulp quality at the end of the sequence. Finally, the pulp was refined in a PFI mill, and the mechanical and physical properties of the resulting paper were determined. The best pulp quality was achieved at pH 7, at which a lower kappa number, higher pulp brightness, and smaller amount of HexA were observed. Under this condition, however, a larger yield loss and a higher effluent COD load had to be accepted. After the complete bleaching sequence, the enzymatic treatments yielded pulps with higher brightness and viscosity as well as with a lower kappa number. The enzymatic treatments resulted in small changes in the mechanical and physical properties of the paper handsheets produced.
Climate response of cell characteristics in tree rings of Picea crassifolia
Authors: Xu Jinmei , Lu Jianxiong , Bao Fucheng , Evans Robert , Downes Geoffrey M. 
Published: September 2012

Abstract
Dimensions of dated tree rings are an important tool of dendroclimatology. However, the relationships between climatic variables and cell diameter and cell wall thickness are not yet clearly elaborated. In the present article, year-to-year cell characteristics, ring width, and wood density of Picea crassifolia trees growing in northwestern China have been measured with high resolution by means of the instrument SilviScan-3. The response function analysis showed that climate explained 51% of the variation of cell radial diameter chronology, 48% of wood density, 40% of cell wall thickness, and 37% of ring width. Cell wall thickness and wood density responded significantly and positively to temperature, and the response to precipitation was negative, while the opposite was true for cell radial diameter and ring width. Cell wall thickness and wood density were pronounced (statistically significant) to temperature in September and precipitation in May and August. Cell radial diameter responded significantly to temperature in June and July, and precipitation, in August. For ring width, the temperature in July was important. Accordingly, cell characteristics are sensitive to climate, and the findings could be useful in the field of dendroclimatology.
Compressive-torsion DMA of yellow-poplar wood in organic media
Authors: Chowdhury Sudip , Frazier Charles E. 
Published: September 2012

Abstract
This work continues the introduction of the dynamic mechanical analysis (DMA) of wood in a novel stress mode, compressive-torsion. The glass/rubber transition in yellow-poplar (Liriodendron tulipifera) wood was measured under saturation in four organic solvents: N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), ethylene glycol, and glycerol. Systematic measurement of the linear viscoelastic response (LVR) revealed a complex relationship of LVR with grain orientation, temperature and solvent. This indicates that special care is required when analysis within the LVR is critical. Glass transition temperatures (Tgs) of swollen wood showed an inverse relationship with solvent induced volumetric swelling. DMF and NMP both caused volumetric swelling of ≥25%, and the corresponding Tgs were near 50°C. Ethylene glycol and glycerol caused volumetric swelling <25% and the corresponding Tgs were ≥100°C. Glycerol showed significantly higher solvolytic power than ethylene glycol. Glycerol plasticized wood underwent irreversible swelling when heated beyond the Tg, causing a reduction in the effective crosslink density and in the Tg. Consistent with the literature, the observed Tg grain dependency was highly varied. The weakest plasticizer, glycerol, produced a prominent Tg grain dependency, whereas grain dependency was variable in the stronger swelling agents. This study demonstrates the importance of researching lignocellulose rheology in a greater variety of organic liquids, to achieve new perspectives into the structure/property relationships of lignocellulose, and aspects of processing in organic media.
Measurement of intra-ring wood density by means of imaging VIS/NIR spectroscopy (hyperspectral imaging)
Authors: Fernandes Armando , Lousada José , Morais José , Xavier José , Pereira João , Melo-Pinto Pedro 
Published: September 2012

Abstract
This paper reports a novel application of hyperspectral imaging (a spectroscopic technique) for measuring wood density profiles at the growth ring scale. The measurements were performed with a spatial resolution of 79 µm. In the present case, hyperspectral imaging was used to measure wood sample reflectance for light in the wavelength range between 380 and 1028 nm, with a resolution of approximately 0.6 nm. The work was performed with 34 samples collected from 34 trees of Pinus pinea. A total of 34,093 density points were used to create and validate a partial least-squares (PLS) regression that converts spectroscopic reflectance data into density values. The coefficient of determination value between the present method and X-ray microdensitometry is 0.810 with a root mean squared error of 6.54×10-2 g.cm-3.
Convenient preparation of a β-O-4-type lignin model trimer via KOH-catalyzed hydroxymethylation and a new protection method
Authors: Lahtinen Maarit , Haikarainen Anssi , Sipilä Jussi 
Published: September 2012

Abstract
Lignin, as the second most abundant biopolymer on earth, is one of the targets for plant biorefinery studies. Its complex chemical behavior is frequently studied by dimeric, trimeric, etc. model compounds, preferably with a β-O-4-type structure. In the present study, a convenient synthesis of a β-O-4-type trimeric model compound possessing a free syringylic hydroxyl has been investigated. Two key modifications were in focus: (1) Protection of the aliphatic hydroxyl groups of the starting phenolic dimer prior to the SN2 displacement reaction before introducing the syringylic moiety with 2,2-dimethoxypropane. (2) The hydroxymethylation step to introduce the full side chain moiety. When this reaction was performed in dioxane/water in the presence of a catalytic amount of KOH instead of K2CO3, the formation of a side product via dehydration was markedly reduced. In addition, a convenient method for introducing an α,β-epoxide structure in acetophenone is recommended.
Topochemistry of heat-treated and N-methylol melamine-modified wood of koto (Pterygota macrocarpa K. Schum.) and limba (Terminalia superba Engl. et. Diels)
Authors: Mahnert Karl-Christian , Adamopoulos Stergios , Koch Gerald , Militz Holger 
Published: September 2012

Abstract
To broaden the knowledge about the chemical changes at the cell wall level of differently modified tropical hardwoods, heat-treated and N-methylol melamine (NMM)-treated samples of koto (Pterygota macrocarpa) and limba (Terminalia superba) were prepared. UV microspectrophotometry (UMSP) was applied at 278 and 240 nm as specific wavelengths to analyze chemical alterations of the samples caused by heat and NMM treatment, respectively. The absorbance of koto exceeded that of limba before and after treatment, potentially due to the higher extractive content of the former. Regardless of the wood species, the absorbance of the samples increased with increasing intensity of the NMM treatment. Additionally, the absorbance of lignin within the spectrum of 230–350 nm was altered due to the NMM treatment. The functionality of applying specific wavelengths for the analysis of different modification methods of wood was proven. However, the comparison with literature did not show differences in the absorbance, which could be assigned to the characteristics of tropical hardwoods.
Behavior of xylans from Eucalyptus species. Part 1. The influence of structural features of eucalyptus xylans on their retention in kraft pulp
Authors: Magaton Andréia S. , Silva Teresa Cristina F. , Colodette Jorge Luiz , Piló-Veloso Dorila , Milagres Flaviana Reis 
Published: September 2012

Abstract
4-O-methylglucuronoxylans were isolated from the wood and pulp of different Eucalyptus species (E. dunni, E. grandis, E. nitens, E. urograndis and E. urophylla) and characterized by 1H NMR spectroscopy and size-exclusion chromatography (SEC). The content of 4-O-methylglucuronic acid (MeGlcA) varied between the eucalyptus species from 1.90 to 2.80 expressed as MeGlcA/10 xyloses, whereas in the pulp, the total uronic acid content was approximately 1.02, from which the half was hexenuronic acid (HexA). From the MeGlcA linked to the xylan chain 9–26% are substituted in position O-2 by hexose units. The Mw of the xylans extracted from wood ranged between 26.1 and 28.4 kDa. The retention of 4-O-methylglucuronoxylans (51.3–58.7%) during kraft pulping was high, and the retention is related to the content of MeGlcA group, the content of MeGlcA group substituted at O-2, and the average molecular weight of the xylans. The parameters observed affect the overall pulp yield and pulp properties.
Fractal dimension analysis of void size in wood-strand composites based on X-ray computer tomography images
Authors: Li Peng , Wu Qinglin , Tao Yubo 
Published: September 2012

Abstract
Oriented strandboards were constructed from various combinations of mixed hardwood flakes. Fractal dimension of void size (FDVS) in the manufactured samples was studied by means of X-ray computer tomography images and a computer image processing technique. The FDVS value was high in the panel surface layers and decreased toward the panel center, and the FDVS decrement was linear to increased porosity. At the same overall porosity level, the FDVS varied as function of void distribution. FDVS could be a useful additional parameter for characterizing the internal void structure of strand-based wood composites.