Contributions of generators for power flow and loads in a power system

Because of the introduction of deregulation and competition in the electricity supply industry, large numbers of IPPs (Independent Power Producers) will get into the market. It has become much more important to be able to determine which generators are supplying a particular load, which generator is responsible for transmission line congestion, and what is each generator's contribution to the system losses. In this paper, we propose a way to calculate these contributions automatically. The applicability of the proposed technique is demonstrated using the EAST 10 47‐bus power system. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 144(3): 28–35, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10181     

Interaction among fractions in mesophase pitches derived from AlCl3-modified ethylene tar

The anisotropic development is studied of mesophase pitches prepared from modified ethylene tar (ETP) using AlCl₃, of fractions separated by benzene, tetrahydrofuran (THF) and pyridine, and of mixed fractions, to find structural factors affecting fusibility and optical anisotropy of mesophase pitch. Annealing was carried out at 360° C for 10 min. Each fraction developed a unique optical anisotropy quite different from that of the parent mesophase pitch. The lightest fraction (soluble in benzene) was highly fusible with small numbers of small anisotropic spheres. The heaviest fraction (insoluble in pyridine) was infusible and exhibited a total mosaic anisotropy. In contrast, mixed fractions behaved like the parent mesophase pitch in terms of liquid crystal behaviour. The extent of anisotropy and fusibility after annealing were strongly dependent on the preparatory conditions of the parent mesophase pitch. The fusibility of mixed fractions is ascribed to the dissolving ability of the fusible fraction and the solubility of the infusible fraction at the annealing temperature. Small molecules in the lighter fractions also contribute to anisotropy when they are located in interlayer positions between the larger aromatic molecules which constitute liquid crystals. Such co-operative properties of constituent molecules of the mesophase pitch can be described in terms of a practical compatibility.     

A new programming environment with a multi-display terminal and early experiences with it

The authors have developed an extended intelligent terminal system MDPS with four CRT displays controlled by microprocessors and with useful programming tools in order to achieve a high-level programming environment. The system is based on the fact that reference to, comparison among, and utilization of various kinds of information are the basic but essential actions in the programming environment. Users can arrange various kinds of information spatially using simple concepts “text” and “page” of MDPS. MDPS has several advantages over conventional terminal systems.     

Economical preventive control of power flow after disturbances in the decentralized power system

This paper discusses the preventive controls of the generator outputs to improve security in the decentralized power system. Preventive controls of the power system can improve security level. However, the preventive control requires too much computation time because of too many considerable faults in the power system. Multiarea decentralization can be considered to reduce computation time of the power flow calculation. It is assumed that the effects of disturbances in the external systems are relatively smaller than the effects of disturbances in the study area. Linearized sensitivity analysis is used to evaluate the effects of the external systems to reduce computation time. Linear programming is used to determine the control signals of generators considering the incremental cost of generators. The New England 38 buses system is used as an example system to check the validity of the algorithm in this paper. The calculations of the example system show satisfactory results.     

Algorithms for Extracting Correct Critical Points and Constructing Topological Graphs from Discrete Geographical Elevation Data

Researchers in the fields of computer graphics and geographical information systems (GISs) have extensively studied the methods of extracting terrain features such as peaks, pits, passes, ridges, and ravines from discrete elevation data. The existing techniques, however, do not guarantee the topological integrity of the extracted features because of their heuristic operations, which results in spurious features. Furthermore, there have been no algorithms for constructing topological graphs such as the surface network and the Reeb graph from the extracted peaks, pits, and passes. This paper presents new algorithms for extracting features and constructing the topological graphs using the features. Our algorithms enable us to extract correct terrain features; i.e., our method extracts the critical points that satisfy the Euler formula, which represents the topological invariant of smooth surfaces. This paper also provides an algorithm that converts the surface network to the Reeb graph for representing contour changes with respect to the height. The discrete elevation data used in this paper is a set of sample points on a terrain surface. Examples are presented to show that the algorithms also appeal to our visual cognition.     

Influence of residual stresses and loading frequencies on corrosion fatigue crack growth behavior of weldments

The effect of residual stresses and loading frequencies on corrosion fatigue crack growth behavior under synthetic seawater with a free corrosion potential was examined using center-cracked tension (CCT) and single edge-cracked tension (SECT) specimens machined from mild steel butt-welded joints and the parent material. A series of fatigue crack growth tests were carried out with a sinusoidal loading wave form at a stress ratio of 0.05 with a loading frequency of 0.017 to 6.7 Hz. The results show that the crack growth resistance of a weld metal in the SECT specimen is higher than that in the CCT specimen regardless of testing conditions. The discrepancy is attributed to the differences in residual stress distribution at the crack tip in the two specimen geometries. The crack growth rate of the weld metal in the CCT specimen in seawater increased with decreasing loading frequency. The acceleration of the crack growth rate may be related to the occurrence of brittle striation or cleavage due to hydrogen embrittlement. It was found that the corrosion fatigue crack growth rate of a welded joint with tensile residual stress can be predicted using the effective stress intensity factor range, which takes into account both the residual stress and the loading frequency effects.     

NMR study on sulfonation of internal olefins

Terminal olefins can be converted into the corresponding sulfonates by sulfonation with SO₃ followed by hydrolysis, the products are used as detergent ingredients. Although internal olefins were also expected to be good feed stocks, it was difficult to convert them into the corresponding sulfonates with as good of a yield as that of terminal olefins under the same synthesis conditions. Our studies have been carried out in order to clarify the reason for poorer conversion of the internal olefins. It was found by a nuclear magnetic resonance spectroscopic study that the major components of the sulfonated intermediate of internal olefins wereβ-sultones, the amounts of which were usually very small in sulfonated terminal olefins. A portion of theseβ-sultones was desulfonated, depending on temperature, to the original olefins and the corresponding sulfate salts during alkaline hydrolysis. The prevention of desulfonation of theβ-sultones in the hydrolysis process was one of the most important aspects for the production of internal olefin sulfonates. Finally, by keeping the hydrolysis temperature below 35°C, the conversion of internal olefins into sulfonates was achieved with the same yield as that of conventional terminal olefins.     

High-performance genetic analysis on microfabricated capillary array electrophoresis plastic chips fabricated by injection molding

We have developed a novel technique for mass production of microfabricated capillary array electrophoresis (mu-CAE) plastic chips for high-speed, high-throughput genetic analysis. The mu-CAE chips, containing 10 individual separation channels of 50-microm width, 50-microm depth, and a 100-microm lane-to-lane spacing at the detection region and a sacrificial channel network, were fabricated on a poly(methyl methacrylate) substrate by injection molding and then bonded manually using a pressure-sensitive sealing tape within several seconds at room temperature. The conditions for injection molding and bonding were carefully characterized to yield mu-CAE chips with well-defined channel and injection structures. A CCD camera equipped with an image intensifier was used to monitor simultaneously the separation in a 10-channel array with laser-induced fluorescence detection. High-performance electrophoretic separations of phiX174 HaeIII DNA restriction fragments and PCR products related to the human beta-globin gene and SP-B gene (the surfactant protein B) have been demonstrated on mu-CAE plastic chips using a methylcellulose sieving matrix in individual channels. The current work demonstrated greatly simplified the fabrication process as well as a detection scheme for mu-CAE chips and will bring the low-cost mass production and application of mu-CAE plastic chips for genetic analysis.     

Photocatalytic Synthesis of p-Anisaldehyde in a Mini Slurry-Bubble Reactor under Solar Light Irradiation

Dense photocatalyst slurry was employed for the synthesis of p-anisaldehyde under solar light irradiation. An Fe-modified rutile TiO ₂ (Fe-TiO _2, 34.5 m ²/g) photocatalyst was used as a visible-light-responsive photocatalyst. A conventional TiO ₂ (P25, 35 m ²/g) photocatalyst was also examined as a reference catalyst. XRD patterns and diffuse reflectance spectra showed that Fe-TiO ₂ consists of 100 % rutile phase and absorbs more visible light compared to P25, respectively. The catalyst powder was suspended in an ethyl acetate solution of p-methoxytoluene in the mini-reactor, with oxygen bubbling, under a solar simulator, visible light, and UV LEDs. p-anisaldehyde, as a reaction product, was analyzed by sampling using gas-chromatograph. Regardless of the light source, Fe-TiO ₂ always outperformed P25 in terms of both generation rates (GR) of p-anisaldehyde and energy requirements (ER). It was demonstrated that the highly dense Fe-TiO ₂ slurry was efficient for the synthesis under solar light owing to the small size of the reactor. The small amount of Pt and ZrO ₂ cocatalysts significantly enhanced the GR under solar light. By adopting a visible light responsive Fe-TiO ₂ photocatalyst, the mini slurry-bubble reactor under solar light achieved a high GR per catalyst mass (CM), which is one to two orders higher than that reported by most previous studies with high-power lamps.