Development of expert system for operation at substation

An expert system that offers support information in substation fault occurrence is described, focusing on a method for fault section estimation. This system edits fault information and estimates the fault section. With respect to the fault section. With respect to fault section estimation, a method that makes maximum use of sequential information on protective relay and circuit breaker operation even for complicated fault conditions involving multiple faults and incorrect operation or incorrect nonoperation of protective relays and circuit breakers. This system is undergoing field test in a commercial EHV substation, and so far normal operation is reported     

Thermoelectric properties of Mn-doped iron disilicide ceramics fabricated from radio-frequency plasma-treated fine powders

Fine particles of Fe0.92Mn0.08Si2.00, 200 nm in size, were produced using a high-frequency plasma. The powders were sintered at temperatures between 1323 and 1423 K in vacuum and then heat treated at 1073 K to transform them into thermoelectric semiconducting iron disilicide. The relative density of the samples was as low as 70–77%, and the microstructure was composed of several tens of micrometre grains and continuous pores. The sample sintered at 1423 K, in particular, showed a figure of merit, Z, of 2.0×10-4K-1 at 870 K which was 20% larger than those previously reported. The increase in Z was found to be attributable to the increase in Seebeck coefficient and the decrease in thermal conductivity. This revised version was published online in November 2006 with corrections to the Cover Date.     

A forced gas-cooled single-disk window using silicon nitride composite for high power CW millimeter waves

Silicon nitride composite as a candidate of a window material for high power CW (Continuous Wave) millimeter-waves was high power tested especially with a surface cooling by impinging gas nitrogen jets on the single-disk surface. Gas-cooling dramatically suppressed the temperature of the window disk even with gas flow rate of around 100 l/min. With gas cooling of 465l/min., 130kW CW power of HE₁₁ mode could be transmitted through the silicon nitride window with a diameter of 88.9mm. The peak window temperature was completely saturated on 123.6 °C. Without gas-cooling it did not saturate and reached 323 °C during 30 seconds pulse. A possibility of 1MW CW single disk Brewster windows with a forced gas-cooling is discussed, resulting in convinced prospects of the windows with realistic size and thickness.     

Standardization of VSAT communication systems in the CCIR

This paper presents an overview of the CCIR Recommendations on VSAT systems. The first part presents the activities of the CCIR Task Group 4/2 which was created in 1990 and issued five Recommendations for VSAT earth-stations. These Recommendations specify the RF characteristics of the VSAT earth-stations and their maintenance functions. The TG 4/2 finished its task in 1991. The second part of this paper presents the activities of the CCIR Task Group 4/3 which was created in 1991 for the preparation of Recommendations on the connection of VSAT networks with the public switched networks. The activities of the TG 4/3 are still going on, and the Draft Recommendations will be formalized in two more meetings. The subjects of dicussion and the expected outcomes will be briefly presented.     

Radiotherapy for carcinoma of the buccal mucosa: analysis of prognostic factors]

The radiotherapeutic results of 55 patients with carcinoma of the buccal mucosa were analyzed to determine the prognostic factors and appropriate treatment modality. They were classified into 5 groups according to treatment modality: group A (preoperative radiotherapy followed by surgery), group B (interstitial implant), group C (electron therapy), group D (mainly external radiotherapy) and group E (external radiotherapy followed by mold therapy with remote afterloading system). The overall 5-year survival rates for groups A, B, C, D, E and the entire group were 50%, 61%, 67%, 29%, 25% and 48%, respectively. The cumulative 5-year local control rates for groups A through E were 81%, 94%, 75%, 33% and 25%, respectively. In univariate analysis, T stage (T1-2 vs. T3-4), N stage (N0 vs. N1-3), clinical stage (II vs. III-IV), histologic grade (well differentiated vs. moderately and poorly differentiated) and treatment modality (A-C vs. D-E) were significantly related to overall survival (p < 0.05). Multivariate analysis revealed that treatment modality (groups A-C) and N0 stage were significantly associated with favorable prognosis (p < 0.05). These results suggest that interstitial implants are comparable with surgery for T1 to early T3 lesions, with or without slight invasion to the bucco-alveolar sulci or retromolar areas, that can be treated with a single-plane implant.     

Analysis of terminal voltage waveform of AC exciting synchronous generators

Recently, adjustable speed hydroelectric power systems have been developed. In those power systems, ac exciting synchronous generators are used instead of the ordinary salient-pole-type synchronous machines. However, some higher harmonic sequences are included in the distribution of air-gap magnetic flux density and in the terminal voltage waveform of the ac exciting synchronous machines because these machines have open winding slots. To develop better machines without terminal voltage waveform distortions, an evaluation method of the terminal voltage harmonics has been needed. This paper describes the mechanism of higher harmonics generation qualitatively and proposes an analytical method of no-load terminal voltage waveforms on the basis of two-dimensional magnetic field analysis considering movement of the rotor for quantitative higher harmonics analysis. The analytical results of higher harmonics show good agreement with the experimental ones.     

B70 antigen is a second ligand for CTLA-4 and CD28

The membrane antigen B7/BB1 (refs 1, 2) is expressed on activated B cells, macrophages and dendritic cells, and binds to a counter-receptor, CD28, expressed on T lymphocytes and thymocytes. Interaction between CD28 and B7 results in potent costimulation of T-cell activation initiated through the CD3/T-cell receptor complex. Discrepancies between results with anti-CD28 and anti-B7 antibodies have suggested the existence of a second ligand for CD28 and CTLA-4 (refs 3, 6-8). We have generated a monoclonal antibody, IT2, that reacts with a 70K glycoprotein (B70). B70 complementary DNA was cloned from a B-lymphoblastoid cell line library and encodes a new protein of the immunoglobulin superfamily with limited homology to B7. B70 is expressed on resting monocytes and dendritic cells and on activated, but not resting, T, NK and B lymphocytes. IT2 substantially inhibited the binding of a CTLA4-immunoglobulin fusion protein to human B-lymphoblastoid cell lines and, together with anti-B7 antibody, completely blocked CTLA-4 binding. Further IT2 efficiently inhibited primary allogeneic mixed lymphocyte responses. These findings indicate that B70 is a second ligand for CD28 and CTLA-4 and may play an important role for costimulation of T cells in a primary immune response.     

Endothelin-1 is an autocrine/paracrine factor in the mechanism of angiotensin II-induced hypertrophy in cultured rat cardiomyocytes

To elucidate the cellular mechanism by which angiotensin II (ANG II) induces cardiac hypertrophy, we investigated the possible autocrine/paracrine role of endogenous endothelin-1 (ET-1) in ANG II-induced hypertrophy of neonatal rat cardiomyocytes by use of synthetic ET-1 receptor antagonist and antisense oligonucleotides to preproET-1 (ppET-1) mRNA. Northern blot analysis and in situ hybridization revealed that ppET-1 mRNA was expressed in cardiomyocytes, but, to a lesser extent, in nonmyocytes as well. ANG II upregulated ppET-1 mRNA level by threefold over control level as early as 30 min, and it stimulated release of immunoreactive ET-1 from cardiomyocytes in a dose- and time-dependent manner. ET-1 stimulated ppET-1 mRNA levels after 30 min in a similar fashion as ANG II. Tetradecanoylphorbol-acetate (10(-7) M) mimicked the effects of ANG II and ET-1 on induction of ppET-1 mRNA. ANG II-induced ppET-1 gene expression was completely blocked by protein kinase C inhibitor H-7 or by down-regulation of endogenous protein kinase C by pretreatment with phorbol ester. ET-1 and ANG II stimulated twofold increase [3H]leucine incorporation into cardiomyocytes, whose effects were similarly and dose dependently inhibited by endothelin A receptor antagonist (BQ123). Introduction of antisense sequence against coding region of ppET-1 mRNA into cardiomyocytes resulted in complete blockade with ppET-1 mRNA levels and [3H]leucine incorporation stimulated by ANG II. These results suggest that endogenous ET-1 locally generated and secreted by cardiomyocytes may contribute to ANG II-induced cardiac hypertrophy via an autocrine/paracrine fashion.     

Global warming and developing countries: The possibility of a solution by accelerating development

There are concerns that the rapid development of the developing countries will hasten global warming and exacerbate resource problems. That is to say, it is quite possible that we cannot solve the North-South problem while at the same time containing global warming and conserving fossil fuels. But this paper attempts to show that, on the contrary, the fast development of these countries might very well bring about a long-term solution of the global warming problem. A model incorporating development stage theory is built and used to calculate by region the world's economic growth, population growth, energy supply and demand, CO₂ emissions and other items up to the end of the 21st century. Results indicated that if in 2100 world population is about 10 billion (it was 5.1 billion in 1990), world GDP is US$200 trillion (1987 prices; it was US$20 trillion in 1990) and CO₂ emissions are 10 billion tonnes (carbon equivalent; they were 5.8 billion tonnes in 1990), there will be fairly good prospects for solving the North-South, fossil fuel exhaustion and global warming problems. Making this scenario happen will require accelerating development of the developing countries so they quickly join the ranks of the developed countries, expediting the shift to renewable energy in the developed countries by imposing carbon taxes, transferring energy saving technologies from the developed to the developing countries, and other efforts.