Optimal design of water distribution networks with reliability considerations

The overall aim of this research has been to develop new algorithms and computer software that may be used to assess the reliability of water distribution systems. Such a tool can be used by design engineers to create systems which are both economical in total cost commensurate with meeting targets for a specified level of reliability.The introduction describes how water supply and distribution systems are normally designed, what they comprise and problems associated with failure or lack of availability of an adequate supply to the end user. This is followed by a resume of current methods and algorithms for the analysis of networks and a detailed examination of the previous work on network optimisation and reliability. Three main algorithms exist for the analysis of water networks. These are the Hardy-Cross methods, the Newton-Raphson methods and the Linear method. A computer program based on the Linear method, which is known to be the most reliable, is proposed for the hydraulic analysis part of the present work. With respect to reliability, a full discussion of the topic, including all the various factors which influence it such as the stochastic nature of customer demands, the apparently random occurrence of pipe breakages and the concept of repair time, is presented. A reliability analysis model, that incorporates simultaneously the three reliability factors mentioned, for the assessment of nodal and system availabilities, is proposed, from which an efficient computer program has been developed and tested. Two models for the design of optimal water distribution systems, based on reliability criteria, have been developed, programmed and tested. The first model makes use of the entropy principle for producing 'reliable' distributions of flow and the Linear Programming technique is used for computation of the least cost design. In the second model, however, a Genetic Algorithm procedure, that incorporates the new reliability analysis model and which is superior to other models has been formulated. The thesis concludes with a comparison between the two methods formulated as a result of this research and applied to realistic practical systems, plus suggestions for further work to improve the optimisation of water distribution networks

Endometriotic Mass After Hysterectomy in a 61 Year Old Post-menopausal Woman: A Case Report and Update.

Endometriosis is a common, hormone-dependent gynecologic disease. Undiagnosed in large proportion of women, managing therapies depend on the impact of quality of life and includes hormonal treatment and pelvic surgery. Less likely endometriosis can occur in post-menopausal women. Malignant transformation of endometriosis is a rare but well-described process, most of time occurring in the ovary, and justifies the practitioner not to underestimate this pathology. We present a case of a 61 year old woman with a symptomatic endometriotic pelvic mass, status post hysterectomy, with no history of endometriosis diagnosed beforehand

Reliability and tolerance comparison in water supply networks

The final publication is available at Springer via http://dx.doi.org/10.1007/s11269-010-9753-2Urban water supply is a high priority service and so looped networks are extensively used in order to considerably reduce the number of consumers affected by a failure. Looped networks may be redundant in connectivity and capacity. The concept of reliability has been introduced in an attempt to quantitatively measure the possibility of maintaining an adequate service for a given period. Numerous researchers have considered reliability as a measure of redundancy. This concept is usually implicit, but some researchers have even stated it explicitly. This paper shows why reliability cannot be considered a measure of redundancy given that branched networks can achieve high values of reliability and this would deny the fact that a looped network is more reliable than a branched network with a similar layout and size. To this end the paper discusses two quantitative indices for measuring expected network behavior: reliability and tolerance. These indices are calculated and a comparison is made between looped, branched, and mixed networks. © 2011 Springer Science+Business Media B.V.The authors wish to acknowledge the support received from project IDAWAS, DPI2009-11591, of the Directorate-General of Research at the Spanish Ministry of Education, the grant PAID-02-09 for a stay at the Universidad Politecnica de Valencia by the first author, and a grant MAEC-AECI 0000202066 awarded to the second author by the Ministerio de Asuntos Exteriores y Cooperacion of Spain. The use of English in this paper was revised by John Rawlins; and the revision was funded by the Universidad Politecnica de Valencia, Spain.Martínez-Rodríguez, JB.; Montalvo Arango, I.; Izquierdo Sebastián, J.; Pérez García, R. (2011). Reliability and tolerance comparison in water supply networks. Water Resources Management. 25(5):1437-1448. https://doi.org/10.1007/s11269-010-9753-2S14371448255Bao Y, Mays LW (1990) Model for water distribution system reliability. J Hydraul Eng ASCE 116(9):1119–1137Bouchart F, Goulter I (1991) Reliability improvements in design of water distribution networks recognizing valve location. Water Resour Res 27(12):3029–3040Carrión A, Solano H, Gamiz ML, Debón A (2010) Evaluation of the reliability of a water supply network from right-censored and left-truncated break data. Water Resour Manag, Springer Sci 24:2917–2935. Published online: 28 January 2010Chiong C (1985) Optimización de redes cerradas, Doctoral Thesis, CIH-CUJAE, Havana (in Spanish)Christodoulou SE (2010) Water network assessment and reliability analysis by use of survival analysis. Water Resour Manag, Springer Sci, Published online: 19 June 2010Cullinane MJ, Lansey KE, Mays LW (1992) Optimization-availability-based design of water distribution networks. J Hydraul Eng ASCE 118(3):420–441Duan N, Mays LW, Lansey KE (1990) Optimal reliability-based design of pumping and distribution systems. J Hydraul Eng ASCE 116(2):249–268Goulter I (1992) Systems analysis in water distribution network design: from theory to practice. J Water Resour Plan Manage ASCE 118(3):238–248Goulter I (1993) Modern concepts of a water distribution system. Policies for improvement of networks with shortcomings. In: Cabrera E, Martínez F (eds) Water supply systems: state of the art and future trends, Valencia (Spain). Comput Mech Publ, Southampton, pp 121–138Goulter I, Bouchart F (1990) Reliability-constrained pipe network model. J Hydraul Eng ASCE 116(2):211–229Gupta R, Bhave R (1994) Reliability analysis of water distribution systems. J Environ Eng ASCE 120(2):447–460Jacobs P, Goulter I (1991) Estimation of maximum cut-set size for water network failure. J Water Resour Plan Manage ASCE 117(5):588–605Jowitt P, Xu C (1993) Predicting pipe failure effects in water distribution networks. J Water Resour Plan Manage ASCE 119(l):18–31Kalungi P, Tanyimboh TT (2003) Redundancy model for water distribution systems. Rel Eng Syst Safety 82(3):275–286Khomsi D, Walters GA, Thorley ARD, Ouazar D (1996) Reliability tester for water-distribution networks. J Comput Civ Eng ASCE 10(l):10–9Lansey K, Duan N, Mays LW, Tung YK (1989) Water distribution system design under uncertainty. J Water Resour Plan Manage ASCE 115(5):630–645Loganathan GV, Shah MP, Sherali HP (1990) A two-phase network design heuristic for minimum cost water distribution systems under a reliability constraint. Eng Optim 15(4):311–336Martínez JB (2007) Quantifying the economy of water supply looped networks. J Hydraul Eng ASCE 133(1):88–97Martínez JB (2010) Cost and reliability comparison between branched and looped water supply networks. J Hydroinform IWA 12(2):150–160Morgan DR, Goulter IC (1985) Optimal urban water distribution design. Water Resour Res 21(5):642–652Park H, Leibman J (1993) Redundancy-constrained minimum-cost design of water distribution networks. J Water Resour Plan Manage ASCE 119(l):83–98Pinto J, Varum H, Bentes I, Agarwal J (2010) A theory of vulnerability of water pipe network. Water Resour Manag 24:4237–4254. Springer Science, Published online: 6 May 2010Quimpo R, Shamsi U (1991) Reliability-based distribution system maintenance. J Water Resour Plan Manage ASCE 117(3):321–339Su Y, Mays LW, Duan N, Lansey K (1987) Reliability based optimization model for water distribution systems. J Hydraul Eng ASCE 113(12):1539–1556Tanyimboh TT, Tabesh M, Burrows R (2001) Appraisal of source head methods for calculating reliability of water distribution networks. J Water Resour Plan Manage ASCE 127(4):206–213Walski TM, Weiler JS, Culver T (2006) Using criticality analysis to identify impact of valve location. In: Proc 8th annual water distrib systems analysis symposium, August 27–30, Cincinnati, Ohio, USA,Walters GA, Knezevic J (1989) Discussion of ‘Reliability based optimization model for water distribution systems’ by Su, Y., Mays, L. W. , Duan, N., and Lansey, K. J Hydraul Eng ASCE 115(8):1157–1158Xu C, Goulter I (1997) Simulation-based optimal design of reliable water distribution networks. In: Zayegh A (ed) Proc 3rd int conf on modeling and simulation. Victoria University of Technology, Melbourne, pp 107–112Xu C, Goulter I (1998) Probabilistic model for water distribution reliability. J Water Resour Plan Manage ASCE 124(4):218–228Xu C, Goulter I (1999) Reliability based optimal design of water distribution networks. J Water Resour Plan Manage ASCE 125(6):352–362Xu C, Goulter I (2000) A model for optimal design of reliable water distribution networks. In: Blain WR, Brebbia CA (eds) Hydraulic engineering software VIII. WIT, Southampton, pp 71–8

Optimal design of water distribution networks with reliability considerations

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The Impact of Dual-Tasking on Sentence Comprehension in Children with Specific Language Impairment

Purpose: This study assesses the hypothesis of a limitation in attentional allocation capacity as underlying poor sentence comprehension in children with SLI. Method: Fifteen children with SLI, 15 age-matched controls, and 15 grammar-matched controls. Sixty sentences were presented in isolation, and 60 sentences were presented with a concurrent non-linguistic target-detection task. If poor attentional allocation capacity is a core deficit in SLI, they should be impaired to a greater extent in the dual task condition relative to the grammatical-age controls. On the contrary, a comparable performance decrement under the dual-task condition in children with SLI and younger language controls would attest of a limitation in attentional allocation capacity in children with SLI that is not disproportionate to their language level. Results: Sentence comprehension was affected by the dual-task condition to a greater extent in children with SLI relative to age-controls, but not relative to grammatical-controls. Conclusions: Our study does not support limitations in attentional allocation capacity as representing a core deficit in SLI. Rather, our data show that these children show attentional allocation capacity comparable to that of younger children having similar language level, suggesting that SLI is characterized by a slowed development of both attentional and language domains