Approach and structure of stabilizing control system preventing an extension of synchronism loss

Recently, large-capacity power stations have been built far from load centers with long-distance transmission lines. Therefore, if a fault occurs at the line, generators in the large-capacity power station may lose synchronism from the remaining generators [1, 3]. To prevent an extension of loss of synchronism to other generators, fast shedding of some generators is an effective measure. The following methods have been proposed so far: A method [3] based on energy function approach; and a method [2] which estimates and predicts the relative swing among generators using data measured on-line at each generator and proposes shedding some generators for stabilization. This method requires a large communication network for an exchange of data between power stations. This paper presents a new stabilizing method and a newly developed stabilizing control system which does not require a large communication network because it utilizes generator output, voltage and current measured on-line in the vicinity of the large-capacity power station. Using these measured data, the system estimates and predicts the relative swing between generators in the large-capacity power station and the remaining generators. Finally, the number of generators to be shed for stabilization is decided and shedding is performed. Configuration and characteristics of the developed stabilizing control system are shown. The validity of this method is confirmed by simulation and testing using an artificial power system.     

Development of Concrete Bridge Rating Prototype Expert System with Machine Learning

Efforts to develop practical expert systems have mostly concentrated on how to implement experience-based machine learning successfully. Recently several active research projects on machine learning have been undertaken from the viewpoint of knowledge-based management. The aim of this study is to develop the Concrete Bridge Rating (Diagnosis) Prototype Expert System with machine learning, employing the combination of a neural network and bidirectional associative memories (BAM). The introduction of machine learning into this system facilitates knowledge-based refinement. By applying the system to an actual in-service bridge, it has been verified that the machine learning method employed that uses the results of questionnaire surveys involving bridge experts is effective for the system.     

High-efficiency electroabsorption in quaternary AlGaInAsquantum-well optical modulators

Quaternary AlGaInAs quantum-well optical modulators operating at 1.55 μm are introduced and demonstrated for the first time. An electron-to-heavy-hole exciton absorption peak shift of over 600 Å is observed for a bias voltage of 6 V. An extinction ratio of 19 dB and high-speed operation over 4 GHz is obtained for this optical modulator     

A dry phantom material composed of ceramic and graphite powder

Details of an artificially synthesized dry phantom material developed for experimental studies of microwave exposure to the human body are shown. The material is solid and can simulate electrical characteristics of high water content biological tissues such as muscles and the brain. The material is composed of high-ϵ_r ceramic powder, graphite powder, and bonding resin. Any shape of phantom models can be constructed to simulate different parts of the body, as well as the head. The paper reports the synthesis technique to obtain the desired complex permittivity and the fabrication technique of the phantom models for usage of specific absorption rate (SAR) estimation at 900 MHz     

Measurement of Rising R-Curve Behavior in Toughened Silicon Nitride by Stable Crack Propagation in Bending

A simple procedure for measuring the R -curve properties of ceramics by a stable fracture test in three-point bending is described. As a typical case, data are displayed for a Si₃N₄ material toughened by the presence of acicular grains in situ grown during the sintering process. The fracture mechanics specimen was a single-edge double-notched beam (SEDNB), whose notch was sharpened to a radius of <10 μm in order to reduce the amount of elastic energy stored at its root prior to crack extension. Furthermore, a stabilizer, specially designed for the bending geometry, was used to control crack stability. During stable extension, the crack could be easily arrested at selected locations of the load-displacement curve, the load quickly released, and the stable crack extension directly measured by the die-penetration technique. The crack resistance, K _R, of the material was calculated from the measured crack extent and the onset load value before unloading. This method enabled us to precisely monitor the critical load value at which the load-displacement curve deviated from linear behavior, as well as crack extensions from a few tens of micrometers to about 1 mm. As an application of this method, the fracture resistance of a Si₃N₄ material with rising R -curve behavior was measured and found to increase from about 5.5 to 9.0 MPaμm^1/2 within a 0.8-mm extension.     

Endothelium-dependent potentiation of prostaglandin F2alpha-induced contractions by (+/-)-[6]-gingerol is inhibited by cyclooxygenase- but not lipoxygenase-inhibitors in mouse mesenteric veins

The mechanism of potentiation of prostaglandin (PG) F2alpha-induced contraction of mouse mesenteric veins by (+/-)-[6-gingerol was investigated in vitro. (+/-)-[6]-Gingerol (0.3mM) potentiated the maximal contraction response elicited by PGF2alpha (0.28 mm) in the presence of intact vascular endothelium, but not in its absence (de-endothelialized preparations). The potentiating effect was completely inhibited by cyclooxygenase inhibitors (0.2 mm aspirin and 0.2 mm indomethacin) and partly by calcium antagonists (2 microM verapamil, 8 nM nitrendipine and 1 microM ryanodine), but not inhibited by nordihydroguaiaretic acid (NDGA), a lipoxygenase inhibitor and ONO-3708, a thromboxane (TX) A2 antagonist. The potentiation by (+/-)-[6]-gingerol is also observed in mesenteric veins of streptozotocin-diabetic mice where the enhancement of PGF2alpha-induced contraction is caused mainly by activation of lipoxygenase. The potentiation of PGF2alpha-induced contraction by (+/-)-[6]-gingerol may be caused by a cyclooxygenase-dependent release of vasoconstrictors, other than PGF2alpha and TXA2, or by inhibiting vasorelaxants released from endothelial cells of mouse mesenteric veins.     

Isolation of flat revertants from human papillomavirus type 18 E6E7 transformed 3Y1 cells by transfection with a rat embryo fibroblast cDNA expression library

A rat embryo fibroblast (REF) cDNA expression library was transfected into 3Y1 cells transformed by human papillomavirus type 18 E6 and E7 genes and 10 flat revertants were isolated. These revertants expressed the same levels of E6 and E7 mRNA as the parent cells, but had greatly reduced ability to form colonies in soft agar. Suppression of transformation was dominant in cell hybrids generated by fusing each revertant with the parental transformed cells. Furthermore, loss of transfected cDNA was observed in re-transformed cell hybrids derived from one flat revertant. Overexpression of the cDNA suppresses the colony-forming efficiency of the cells transformed by E6 and E7 genes.     

Properties of liposomal membranes containing lysolecithin

The diffusion of glucose from phospholipid membranes has been measured in the presence of serum albumin or methylated serum albumin. At neutral pH, serum albumin enhanced the rate at which glucose diffused from liposomes containing more than a certain amount of lysolecithin. Net charge of the membrane is not important for the reaction, since positively charged membranes containing stearylamine showed almost the same reactivity as negatively charged liposomes containing dicetyl phosphate. Carboxylmethylated albumin showed enhancement of the diffusion rate of glucose from negatively but not from positively charged liposomes. The amount of methylated albumin required to affect liposomes was much smaller than the amount of albumin required to damage liposomes containing lysolecithin. Cholesterol incorporation suppressed the sensitivity of liposomes to both proteins, albumin and methylated albumin. The effect of temperature and fatty acid composition of phospholipids on the sensitivity of liposomes to proteins suggests the importance of the fluidity of the membrane, especially in the case of methylated albumin.     

Formation of acrylamide in a processed food model system, and examination of inhibitory conditions

Acrylamide (AAm) is formed from asparagine (Asn) and reducing sugar during cooking of foods at high temperature. We examined the formation of AAm in a model system using a glass fiber filter paper, and looked for suitable conditions for inhibiting AAm formation. In frying, the formation rate was about 10 times that in a moistureless oven. Increase of frying temperature and frying time increased AAm formation when the residual moisture was 5% or less. AAm increased with increasing amount of glucose (Glc) addition up to 1:1 with respect to Asn, but then decreased. On the other hand, in the case of fructose, as the amount added was increased, AAm increased accordingly. The AAm formation rate with respect to Asn increased when valine (Val) was co-present in a Glc and Asn reaction system. Cysteine and lysine inhibited the AAm formation rate. Pathways for the formation of AAm are proposed.