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ABSTRACT: Distribution automation (DA) application for fault management in the electricity distribution networks is one of the main potential remedial actions to reduce customers' outage times and hence improve service reliability. As a result, various automation schemes have been developed and introduced in different countries and by different venders. The impacts of implementing a specific automation scheme on reliability indices of a given distribution system can be different from other available automation schemes. For this reason, when comparing the available automation schemes with each other or with the other reliability improvement measures, it is necessary to perform a course of reliability worth assessment activities in the related decision making process. This paper aims to quantitatively assess the reliability worth of employing an Automatic Loop Restoration Scheme (ALRS) for urban distribution networks. Distributed intelligence and peer-to-peer communication are the main features of this feeder automation scheme. An urban distribution reliability test system is utilized in this paper to perform the reliability worth assessment analyses.
Innovative Smart Grid Technologies Conference Europe (ISGT Europe), 2010 IEEE PES; 11/2010
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ABSTRACT: Loop restoration scheme (LRS) is a special feeder automation (FA) scheme, which is used by utilities to improve distribution system reliability. The LRS is controlled and managed by its automatic control system (ACS). The impacts on distribution system reliability indices of implementing LRS mainly depend on the type of its ACS. Two common types of ACS of LRS are presented and used in this study. Successful operation of ACS is dependent on the protection and automatic control functions of switching devices of LRS. Different failure modes of these switching devices can therefore affect the procedure of ACS in fault detecting, isolating and service restoration. The impacts of failure of protection and automatic control functions of switching devices and fuse of lateral distributors on reliability indices are illustrated. The worth of implementing LRS and its ACS type is represented by the reduction in expected customer interruption cost. A distribution test system is utilised to examine the impacts of two common types of ACS of LRS on the distribution system reliability. Selecting the type of ACS of LRS by utilities relies on the desired level of load-point and system reliability improvement. This study aims to quantitatively assess the impacts of two common types of ACS of LRS on the distribution system reliability.
IET Generation Transmission & Distribution 11/2009; · 1.20 Impact Factor
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ABSTRACT: Implementation of distribution automation (DA) in electric power distribution systems can result in customer satisfaction with improved reliability, consistent quality and high-tech services. Loop restoration strategy (LRS) is a special DA method in the feeder level which is used by electric utilities to improve distribution system reliability. The effects of the implemented LRS on the reliability indices of a given distribution system mainly depend on its automatic control system (ACS). Selecting the type of ACS of LRS by electric utilities relies on the level of improvement required at load points and system oriented reliability indices. A step by step evaluation procedure is proposed in this paper to quantitatively assess the impacts of two common types of ACS of LRS on reliability indices of a distribution reliability test system.
PowerTech, 2009 IEEE Bucharest; 08/2009
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ABSTRACT: Feeder Automation (FA) has been recognized by researchers and utilities as one of the attractive remedial measures to enhance service reliability in the electric power distribution systems. Until now, several kinds of FA schemes have been developed for automating of distribution feeders. They can be categorized into three main approaches: semiautomatic, distributed and centralized schemes. The challenge for the utilities, especially in todaypsilas competitive electricity market, is to identify and evaluate potential FA schemes and determine that appropriate for implementation. In this context, reliability cost/worth assessment plays an important role. This paper aims to propose a step by step evaluation procedure to quantitatively assess the impacts of an advanced centralized FA scheme, designated as the ldquoLow Interruption Systemrdquo(LIS), on reliability worth indices of a typically distribution reliability test system.
Electric Power Conference, 2008. EPEC 2008. IEEE Canada; 11/2008
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ABSTRACT: Automation can greatly enhance distribution-network reliability by speeding up service restoration and thus significantly reduce customer-outage time. The paper presents an approach to assess quantitatively the adequacy of a particular automated distribution scheme designated as the `low interruption system' (LIS). Owing to the use of a high-speed communication system and line sensors, this automated scheme can reduce drastically the number of interruptions, the service interruption time and also the area affected by the fault. This scheme provides a simple and cost-effective way to automate distribution systems in which the remotely controlled switches speed up isolation of faulted sections and the restoration of healthy sections through alternative routes. The step-by-step calculation procedure is presented using a typical small automated distribution system. The proposed technique is then applied to a larger distribution system to examine the effectiveness of the technique and also to examine the level of reliability improvement achieved by automation
IET Generation Transmission & Distribution 04/2007; · 1.20 Impact Factor
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ABSTRACT: We compared three methods: arteriovenous anastomosis, doxorubicin administration, and combination of anastomosis and doxorubicin, with the intention of designing a simple, stable model of chronic heart failure. Twelve dogs were divided into three groups of four. One group received carotid-jugular anastomosis (Ana series), another group received anastomosis and doxorubicin injection (A/D series), and the last group received only doxorubicin (Dox series). Animals were followed for eight weeks. Fifteen different haemodynamic parameters were tracked and compared to baseline values. After eight weeks, diastolic pressure in the right atrium increased from 3.8+/-2.0 mmHg at baseline to 5.3+/-5.9 mmHg in the Ana series, to 6.3+/-3.3 mmHg in the Dox series and to 8.0+/-2.0 mmHg in the A/D series (P<0.05 A/D vs. baseline). Systolic pulmonary wedge pressure increased from 11.6+/-2.0 mmHg at baseline to 15.5+/-3.4 mmHg in the Ana series, 14.0+/-3.7 mmHg in the Dox series and 17.3+/-4.2 mmHg in the A/D series (P = NS vs. baseline). Left ventricular ejection fraction decreased from 53.9+/-10% at baseline to 36.1+/-5.6% in the Ana series (P<0.05 vs. baseline), 31.5+/-5.4% in the Dox series (P<0.05 vs. baseline) and 25.8+/-5.8% in the A/D series (P<0.001 vs. baseline, P<0.05 vs. Ana series and Dox series). In conclusion, eight weeks are not enough to produce stable heart failure using arteriovenous anastomosis alone. Doxorubicin administration alone produces a left ventricular failure. However, a combination of both of these interventions provides a more stable model of right-and left-sided heart failure.
Laboratory Animals 02/2007; 41(1):63-70. · 1.21 Impact Factor
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ABSTRACT: Sperm premature chromatin condensation (PCC) has been considered as the second cause of failed fertilization post-intracytoplasmic sperm injection (post-ICSI). Cytoplasmic factors, including oocyte cytoplasmic immaturity have been suggested to induce PCC sperm. However, recent studies suggest that sperm chromatin anomaly might also lead to PCC sperm. During this study, human sperm from infertile patients with protamine deficiency or with adequate amount of protamine assessed by chromomycin A3 were injected into metaphase II mouse oocyte, treated with colcemid. Chromatin analysis was carried out on the injected oocyte. The results of this study show that contrary to the percentage of intact sperm, percentage of PCC sperm was significantly higher in oocytes injected with protamine deficient sperm (36.43 +/- 4.46) compared to oocytes injected with sperm with an adequate amount of protamine (11.99 +/- 3.54, P < 0.001). A significant correlation was also observed between percentage of PCC sperm and protamine deficiency (r = 0.46, P = 0.004). Therefore, it can be suggested that oocytes injected with protamine deficient sperm have a higher chance of forming PCC sperm and may result in failed fertilization post-ICSI.
Andrologia 06/2006; 38(3):92-8. · 1.55 Impact Factor
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ABSTRACT: To review our experience with combined pars plana lensectomy-vitrectomy and open-loop flexible anterior chamber intraocular lens (AC IOL) implantation for managing subluxated crystalline lenses.
Retrospective review of 36 consecutive eyes (28 patients), all of which had subluxated crystalline lenses, managed by pars plana lensectomy-vitrectomy with insertion of an open-loop flexible AC IOL. The study was performed at the Medical College of Wisconsin, Milwaukee, over an 8-year period.
An average preoperative visual acuity of 20/163 (range, 20/25 to hand motions) improved to 20/36 (range, 20/20 to 4/200) with surgery after a mean follow-up of 14 months (range, 1 to 59 months) (P < .001, Student's paired t test). Final visual acuity of 20/40 or better was achieved in 75% of eyes (27/36). Complications included cystoid macular edema (8% [3/36]), pupillary block (6% [2/36]), retinal detachment (3% [1/36]), hyphema (3% [1/36]), wound leak (3% [1/36]), and transient vitreous hemorrhage (3% [1/36]). No persistent ocular hypertension was seen, nor did angle abnormalities or corneal decompensation develop.
Pars plana lensectomy-vitrectomy with AC IOL implantation appears to be an excellent technique for managing subluxated crystalline lenses. It is associated with a significant improvement in visual acuity (P < .001) and avoids many of the complications seen with extraction of a subluxated lens through a limbal wound. Additionally, use of an AC IOL offers a simplified alternative to placement of a ciliary sulcus sutured posterior chamber intraocular lens (PC IOL).
Transactions of the American Ophthalmological Society 01/2000; 98:247-51; discussion 251-3.
