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     

An alternative procedure to intra-arterial aortoinfundibuloplasty

Intra-arterial aortoinfundibuloplasty is a newly developed aortic annular enlargement procedure in which, originally, the annulus was split anteriorly via the main pulmonary arteriotomy. An alternative method of aortoinfundibuloplasty was studied experimentally which creates spiral incisions on the free walls of both great arteries descending together into the aortopulmonary and infundibular septum via both commissures of right and left facing cusps of pulmonary and aortic valves. The valve prosthesis is implanted through this three-dimensional incision, followed by patch reconstruction. The ratio of annular augmentation was three sizes in two animals and four sizes in three animals. Immediate postoperative haemodynamics were satisfactory and there was no significant postoperative increase in systolic pressure gradient at the right ventricular outflow tract and in the right ventricular end-diastolic pressure. This alternative procedure could be applied to cases requiring radical annular enlargement and would give a wider view of both ventricular outflow tracts.     

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.     

Three-dimensional analysis of the vascular system in the rat spinal cord with scanning electron microscopy of vascular corrosion casts. Part 1: Normal spinal cord

Vascular corrosion casts of polyester resin in the normal spinal cord at C4-C6 and C7-T1 were inspected three-dimensionally by scanning electron microscopy in 13 rats. Arteries and veins were easily differentiated by the impression pattern of endothelial nuclei on the casts. The centrifugal arterial system from the sulcal arteries supplied most of the gray and white matter in the ventral and lateral spinal cord. Each sulcal artery supplied only one side of the cord. The average number of sulcal arteries was 2.6 per mm. The centripetal arterial system from the posterior spinal arteries fed the posterior gray and white matter. In contrast with classical concepts, there was no pial arterial plexus on the ventral and ventrolateral surface except for infrequent transverse branches from the anterior spinal artery. In the posterior columns, two types of large veins were identified: the posterior medial septal veins and the posterior oblique veins that drained the posterior columns, medial posterior gray matter, and posterior gray commissure. The remainder of the gray and white matter was drained by the sulcal veins and the radial veins. This method clearly demonstrates the three-dimensional structure of both the arterial and venous system in the rat spinal cord.     

Angina pectoris caused by coronary microvascular spasm

BACKGROUND: Microvascular angina can occur during exercise and at rest. Reduced vasodilator capacity of the coronary microvessels is implicated as a cause of angina during exercise, but the mechanism of angina at rest is not known. Our aim was to test the hypothesis that primary hyperconstriction (spasm) of coronary microvessels causes myocardial ischaemia at rest. METHODS: Acetylcholine induces coronary artery spasm in patients with variant angina. We tested the effects of intracoronary acetylcholine at graded doses in 117 consecutive patients with chest pain (at rest, during exertion, or both) and no flow-limiting (>50%) organic stenosis in the large epicardial coronary arteries. We also assessed the metabolism of myocardial lactate during acetylcholine administration in 36 of the patients by measurement of lactate in paired blood samples from the coronary artery and coronary sinus vein. FINDINGS: Of the 117 patients, 63 (54%) had large-artery spasm, 29 (25%) had microvascular spasm, and 25 (21%) had atypical chest pain. The 29 patients with microvascular spasm developed angina-like chest pain, ischaemic electrocardiogram (ECG) changes, or both spontaneously (two patients) or after administration of acetylcholine (27 patients) without spasm of the large epicardial coronary arteries. Testing of paired samples of arterial and coronary sinus venous blood showed that lactate was produced during angina attack in nine of 11 patients with microvascular spasm. There was more women (p<0.01) and fewer coronary risk factors (p<0.01) in patients with microvascular spasm than in those with large-artery spasm. INTERPRETATION: Coronary microvascular spasm and resultant myocardial ischaemia may be the cause of chest pain in a subgroup of patients with microvascular angina.     

Inhibitory effect of Multiglycosidorum tripterygii on coronary arteriosclerosis after heart transplantation

BACKGROUND: Graft coronary arteriosclerosis (GCA) is the major limiting factor for long-term survival after heart transplantation. In this study, we investigated the effect of Multiglycosidorum tripterygii (MT) on GCA and platelet-derived growth factor A (PDGF-A) mRNA expression of transplanted hearts. METHODS: Two groups of Lewis rats (n=7/group) underwent heterotopic heart transplantation from Wistar-King donors and were treated with either cyclosporine (CsA;10 mg/kg/day) or MT (30 mg/kg/ day). Histological evaluations of rejection and coronary arteriosclerosis, as well as Northern blot analysis on graft PDGF-A mRNA expression were made 60 days after transplantation. RESULTS: Morphometric results indicated no significant difference in rejection between the CsA- and MT-treated groups. However, the extent of GCA in the MT-treated group was significantly less than that seen in the CsA-treated group (P<0.01). The expression of PDGF-A mRNA of cardiac allograft was also significantly suppressed in the MT-treated group when compared with the CsA-treated group (P<0.01). CONCLUSION: MT is superior to CsA in preventing graft coronary arteriosclerosis, and this efficacy is probably associated with the depressed expression of graft PDGF-A mRNA in the MT-treated group.     

Less blood damage in the impeller centrifugal pump: a comparative study with the roller pump in open heart surgery

A centrifugal pump with an impeller (Nikkiso Centrifugal Pump, Model HPM15; Nikkiso Co. Ltd.) was applied to cardiopulmonary bypass (CPB) in 14 patients who underwent elective coronary artery bypass grafting. Serum hemoglobin level, platelet count, and serum beta-thromboglobulin (beta TG) level were measured during CPB. The results were compared with those obtained in a comparative roller pump (RP) group (n = 10). There was no difference in the time on CPB between the NP (109 min) and RP (121 min) groups. The serum beta TG level (ng/ml) was lower in the NP group than in the RP group (obtained 90 min after the initiation of CPB). The plasma-free hemoglobin level also was lower in the NP group than in the RP group (obtained 90 min after the initiation of CPB, 120 min after the initiation of CPB, immediately after the termination of CPB, 3 h after termination of CPB; p < 0.01). There was no significant difference in platelet depletion. The HPM15 pump showed excellent hemodynamic performance with less blood trauma compared with the roller pump in its clinical application to open heart surgery.     

Effects of ubiquitin C-terminal hydrolase L1 deficiency on mouse ova

Maternal proteins are rapidly degraded by the ubiquitin-proteasome system during oocyte maturation in mice. Ubiquitin C-terminal hydrolase L1 (UCHL1) is highly and specifically expressed in mouse ova and is involved in the polyspermy block. However, the role of UCHL1 in the underlying mechanism of polyspermy block is poorly understood. To address this issue, we performed a comprehensive proteomic analysis to identify maternal proteins that were relevant to the role of UCHL1 in mouse ova using UCHL1-deficient gad. Furthermore, we assessed morphological features in gad mouse ova using transmission electron microscopy. NACHT, LRR, and PYD domain-containing (NALP) family proteins and endoplasmic reticulum (ER) chaperones were identified by proteomic analysis. We also found that the 'maternal antigen that embryos require' (NLRP5 (MATER)) protein level increased significantly in gad mouse ova compared with that in wild-type mice. In an ultrastructural study, gad mouse ova contained less ER in the cortex than in wild-type mice. These results provide new insights into the role of UCHL1 in the mechanism of polyspermy block in mouse ova.     

Local out-of-plane deformation of CFRP ablator subjected to rapid heating

This study investigates local out-of-plane deformation of a carbon fiber reinforced phenolic polymer ablator subjected to very rapid heating. Local out-of-plane deformation was measured using a three-dimensional digital image correlation technique at high temperatures. This was achieved by attaching high temperature resistant random patterns on the specimen surface using a ceramic bond. Additionally, blue filters intended for cutting strong infrared radiation from the specimen were also used. This study then discusses the mechanisms of the local out-of-plane deformation under rapid heating conditions in terms of carbonization, pyrolysis gas occurrence, gas pressure storage, and interlaminar debonding due to gas pressure.