Hydraulic Design of a USBR Type II Stilling Basin

The present paper deals with a United States Bureau of Reclamation (USBR) Type II stilling basin, which is characterized by blocks at the end of the chute and a dentated sill at the end of the basin. For this basin, USBR only gives overall design criteria concerning basin length and block dimensions on the basis of the assumption that the hydraulic jump remains confined within the sill. No considerations are provided concerning possible different jump types, pressure regimes, and forces acting on the sill. To comply with such a lack, an experimental campaign was undertaken that focuses on the differences among hydraulic jump types that can occur in a USBR Type II stilling basin. Jump types can range between submerged and spray jump types; accordingly, dimensionless relations are provided to predict jump type and position for assigned boundary conditions, with particular concern about the submerged/nonsubmerged distinction. Considerations about the drag force and drag coefficients are provided, along with estimates of pressure extreme fluctuations. Finally, an evaluation of the dissipation efficiency is presented for both submerged and nonsubmerged jumps, enabling comparisons among different jump types and with classical hydraulic jump. - See more at: http://ascelibrary.org/doi/abs/10.1061/(ASCE)IR.1943-4774.0001150#sthash.ajmk3TuB.dpu

Optimal pump scheduling for urban drainage under variable flow conditions

The paper is focused on the optimal scheduling of a drainage pumping station, complying with variations in the pump rotational speed and a recurrent pattern for the inflow discharge. The paper is structured in several consecutive steps. In the first step, the experimental set-up is described and results of calibration tests on different pumping machines are presented to obtain equations linking significant variables (discharge, head, power, efficiency). Then, those equations are utilized to build a mixed-integer optimization model able to find the scheduling solution that minimizes required pumping energy. The model is solved with respect to a case study referred to a urban drainage system in Naples (Italy) and optimization results are analysed to provide insights on the algorithm computational performance and on the influence of pumping machine characteristics on the overall efficiency savings. With reference to the simulated scenarios, an average value of 32% energy can be saved with an optimized control. Its actual value depends on the hydraulic characteristics of the system

Experimental results on the physical model of an USBR type II stilling basin

The present paper describes the experimental campaign carried on the physical model of the spillway of Lower Diamphwe Dam (Malawi), which is provided with a USBR type II stilling basin. Stilling basins are used in order to reduce the excessive kinetic energy of flowing water downstream of spillways. Specifically, a USBR type II basin is provided with blocks at the end of the chute and with a confining dentated sill; these appurtenances allow to dissipate excess energy with high efficiency. The study focuses on the hydraulic behavior of the stilling basin; tests were carried on for different values of incoming discharge and downstream water depth. Results show the dissipation efficiency of the stilling basin in terms of pressure fluctuation and the variability of the jump type with the hydraulic characteristics of the incoming and the downstream flow depths

Hydropower Potential inWater Distribution Networks: Pressure Control by PATs

Pressure control is one of the main techniques to control leakages in Water Distribution Networks (WDNs) and to prevent pipe damage, improving the delivery standards of a water supply systems. Pressure reducing stations (PRSs) equipped by either pressure reducing valves or motor driven regulating valves are commonly used to dissipate excess hydraulic head in WDNs. An integrated new technical solution with economic and system flexibility benefits is presented which replaces PRSs with pumps used as turbines (PATs). Optimal PAT performance is obtained by a Variable Operating Strategy (VOS), recently developed for the design of small hydropower plants on the basis of valve time operation, and net return determined by both energy production and savings through minimizing leakage. The literature values of both leakages costs and energy tariffs are used to develop a buisness plan model and evaluate the economic benefit of small hydropower plants equipped with PATs. The study shows that the hydropower installation produces interesting economic benefits, even in presence of small available power, that could encourage the leakage reduction even if water savings are not economically relevant, with consequent environmental benefits

A Comparison of Energy Recovery by PATs against Direct Variable Speed Pumping in Water Distribution Networks

Water systems are usually considered low efficiency systems, due to the large amount of energy that is lost by water leakage and dissipated by pressure reducing valves to control the leakage itself. In water distribution networks, water is often pumped from the source to an elevated tank or reservoir and then supplied to the users. A large energy recovery can be realized by the installation of energy production devices (EPDs) to exploit the excess of pressure that would be dissipated by regulation valves. The feasibility of such a sustainable strategy depends on the potential of energy savings and the amount of energy embedded in water streams, assessed by means of efficiency measures. Alternatively, energy savings can be pursued if the water is directly pumped to the network, bypassing the elevated reservoir. This study focuses on the comparison of two solutions to supply a real network, assessed as a case study. The first solution consists of water pumping to a reservoir, located upstream of the network; the excess of energy is saved by the employment of a pump as turbine (PAT). The second scenario is characterized by a smaller pressure head since a direct variable speed pumping is performed, bypassing the reservoir. The comparison has been carried out in terms of required energy, assessed by means of a new energy index and two literature efficiency indices. Furthermore, differing design conditions have been analyzed by varying the pumping head of both the scenarios, corresponding to different distances and elevation of the water source

The spectrum of eye disease in hospitalized adults living with HIV, 1995-2010.

Eye disease is a well-documented complication of HIV infection. Opportunistic infections generally comprised the majority of pre-antiretroviral therapy (ART) eye complications. With the introduction of ART, opportunistic infections diminished. However, early ART regimens were cumbersome regarding side effects and pill burden, making patient compliance difficult. Newer ART regimens are better tolerated and consist of fewer pills, theoretically making compliance easier and therapy more effective. The aim of this chart review study is to examine eye disease epidemiology in HIV patients as ART has evolved. We reviewed 222 admissions at Thomas Jefferson University Hospitals for 188 patients. These cases were divided into two groups. The first group was comprised of patients admitted from 1995 through 2003, while the second group consisted of patients admitted from 2003 to 2010. Eye disease epidemiology was compared between the two groups. Our study did note a significant decrease in eye diseases caused by opportunistic infections in the 2003-2010 patient group. Noninfectious eye disease is a significant complication in this group

Nonsense-mediated decay mechanism is a possible modifying factor of clinical outcome in nonsense cd39 beta thalassemia genotype

Nonsense-mediated mRNA decay (NMD) is a surveillance system to prevent the synthesis of non-functional proteins. In β-thalassemia, NMD may have a role in clinical outcome. An example of premature translation stop codons appearing for the first time is the β-globin cd39 mutation; when homozygous, this results in a severe phenotype. The aim of this study was to determine whether the homozygous nonsense cd39 may have a milder phenotype in comparison with IVS1,nt110/cd39 genotype. Genotypes have been identified from a cohort of 568 patients affected by β-thalassemia. These genotypes were compared with those found in 577 affected fetuses detected among 2292 prenatal diagnoses. The nine most common genotypes, each with an incidence rate of 1.5% or over, and together accounting for 80% of genotype frequencies, underwent statistical analysis. Genotype prevalence was calculated within the overall group. Results are expressed as proportions with 95% confidence intervals; P≤0.05 was considered statistically significant. A binomial distribution was assumed for each group; z-tests were used to compare genotype frequencies observed in the patient group with frequencies in the affected fetus group. In the absence of selecting factors, prevalence of these two genotypes was compared between a cohort of 568 β-thalassemia patients (PTS) and 577 affected fetuses (FOET) detected during the same period. IVS1,nt110/cd39 was significantly more prevalent in FOET than PTS (P<0.0001), while there was no significant difference in prevalence of cd39/cd39 in FOET compared with PTS (P=0.524). These results suggest a cd39 genotype NMD mechanism may be associated with improved clinical outcomes in thalassemia major

Molecular and clinical characterization of albinism in a large cohort of Italian patients.

PURPOSE: The purpose of this study was to identify the molecular basis of albinism in a large cohort of Italian patients showing typical ocular landmarks of the disease and to provide a full characterization of the clinical ophthalmic manifestations. METHODS: DNA samples from 45 patients with ocular manifestations of albinism were analyzed by direct sequencing analysis of five genes responsible for albinism: TYR, P, TYRP1, SLC45A2 (MATP), and OA1. All patients studied showed a variable degree of skin and hair hypopigmentation. Eighteen patients with distinct mutations in each gene associated with OCA were evaluated by detailed ophthalmic analysis, optical coherence tomography (OCT), and fundus autofluorescence. RESULTS: Disease-causing mutations were identified in more than 95% of analyzed patients with OCA (28/45 [62.2%] cases with two or more mutations; 15/45 [33.3%] cases with one mutation). Thirty-five different mutant alleles were identified of which 15 were novel. Mutations in TYR were the most frequent (73.3%), whereas mutations in P occurred more rarely (13.3%) than previously reported. Novel mutations were also identified in rare loci such as TYRP1 and MATP. Mutations in the OA1 gene were not detected. Clinical assessment revealed that patients with iris and macular pigmentation had significantly higher visual acuity than did severe hypopigmented phenotypes. CONCLUSIONS: TYR gene mutations represent a relevant cause of oculocutaneous albinism in Italy, whereas mutations in P present a lower frequency than that found in other populations. Clinical analysis revealed that the severity of the ocular manifestations depends on the degree of retinal pigmentation

Impact dynamics of mud flows against rigid walls

Mud flows represent one of the major causes of natural hazards in mountain regions. Similarly to debris flows, they consist of a hyper-concentrated mixture of water and sediments flowing down a slope and may cause serious damages to people and structures. The present paper investigates the force produced by a dam-break wave of mud impacting against a rigid wall. A power-law shearthinning model is used to describe the rheology of the hyper-concentrated mixture. A onedimensional shallow water model is adopted and a second-order Finite Volume scheme is employed to numerically solve the governing equations. The results indicate that depending on the fluid rheological parameters and on the bottom slope, there exists a minimum value of the wall distance above which the peak force does not exceed the asymptotic value of the hydrostatic final condition. For two different values of the channel slope, the dimensionless value of this lower bound is individuated for several values of the power-law exponent and of a dimensionless Basal Drag coefficient. An estimation of the maximum peak force for wall distance smaller than the minimum value is also provided