Proposal of a Conceptual Model as Tool for the Hydraulic Design of Vegetated Roof

2014 ◽  
Vol 641-642 ◽  
pp. 326-331 ◽  
Author(s):  
Marco Carbone ◽  
Francesca Principato ◽  
Gennaro Nigro ◽  
Patrizia Piro
Keyword(s):  
Conceptual Model ◽  
Quantitative Information ◽  
Full Scale ◽  
Urban Drainage ◽  
Hydraulic Behavior ◽  
Good Ability ◽  
Vegetated Roofs ◽  
Vegetated Roof ◽  
In Series ◽  
Physical Phenomena

Vegetated roof technique is becoming increasingly popular, particularly in highly urbanized areas, among the Sustainable Urban Drainage Systems (SUDS) for urban stormwater management. Several studies [1,2] have shown that vegetated roofs may significantly reducing the runoff volume and hydrograph peaks, as well as slowing the contribution to the urban drainage network.This study proposes a conceptual model to predict the hydraulic behavior of a full-scale physical model of a vegetated roof. The model idealizes the vegetated roof as a system consisting of three individual components in series. A mass balance equation is applied to each block, taking into account the specific physical phenomena occurring in each module [3]. The model is validated using dataset observed from the monitoring campaign carried out on the prototype of a full-scale vegetated roof.This study aims to provide quantitative information about the hydraulic performance of vegetated roofs, and identify the most sensitive parameters for describing the hydraulic behavior. The results show a good ability of the model to fit the measured data.

Wastewater Lagoons in a Cold Climate

1987 ◽  
Vol 19 (12) ◽  
pp. 47-53 ◽  
Author(s):  
J. A. Oleszkiewicz ◽  
A. B. Sparling
Keyword(s):  
Control Mechanism ◽  
Maximum Load ◽  
Domestic Sewage ◽  
Full Scale ◽  
Cold Climate ◽  
Odor Control ◽  
Intermittent Rivers ◽  
In Series ◽  
Break Up ◽  
Lagoon Systems

Severe climate, intermittent rivers and availability of land make facultative lagoon systems the method of choice in treating primarily domestic sewage from smaller municipalities. The lagoons are designed on a recommended maximum load of 55 kgBOD5/ha d to first cell, while the second cell provides storage. The discharge is twice annually and the occurrence of the spring ice break-up odor period is one of the primary criteria limiting this load. Based on full scale performance data, it is demonstrated that, from the standpoint of odor nuisance, the load to the first cell should be kept equal to or less than 35 kg/ha d. Full scale studies of an overloaded lagoon system show the futility of under-ice aeration for odor control. Mechanism of natural odor control during ice break up is elucidated. Upgrading of the overloaded systems or lagoons receiving significant industrial contribution is best achieved by construction of a 3–5 m deep aerated lagoon preceding the two or more facultative cells in series.

The REPAS Study: Reliability Evaluation of Passive Safety Systems

2002 ◽  
Author(s):  
M. E. Ricotti ◽  
F. Bianchi ◽  
L. Burgazzi ◽  
F. D’Auria ◽  
G. Galassi
Keyword(s):  
Initial Conditions ◽  
Natural Circulation ◽  
Quantitative Information ◽  
External Input ◽  
Passive System ◽  
Two Phase ◽  
Passive Safety Systems ◽  
Safety Systems ◽  
Physical Laws ◽  
Physical Phenomena

The strategy of approach to the problem moves from the consideration that a passive system should be theoretically more reliable than an active one. In fact it does not need any external input or energy to operate and it relies only upon natural physical laws (e.g. gravity, natural circulation, internally stored energy, etc.) and/or “intelligent” use of the energy inherently available in the system (e.g. chemical reaction, decay heat, etc.). Nevertheless the passive system may fail its mission not only as a consequence of classical mechanical failure of components, but also for deviation from the expected behaviour, due to physical phenomena mainly related to thermalhydraulics or due to different boundary and initial conditions. The main sources of physical failure are identified and a probability of occurrence is assigned. The reliability analysis is performed on a passive system which operates in two-phase, natural circulation. The selected system is a loop including a heat source and a heat sink where the condensation occurs. The system behavior under different configurations has been simulated via best-estimate code (Relap5 mod3.2). The results are shown and can be treated in such a way to give qualitative and quantitative information on the system reliability. Main routes of development of the methodology are also depicted.

scholarly journals Velocity Distribution Characteristics Of Sea Water In Conductiv Magnetohydrodynamic (MHD) Homopolar Ducts

2015 ◽  
Vol 21 (3) ◽  
pp. 679-687
Author(s):  
Vasile Dobref ◽  
Petrică Popov ◽  
Silvestru Grozeanu
Keyword(s):  
Sea Water ◽  
Flow Characteristics ◽  
Modern Technology ◽  
Optimum Shape ◽  
Channel Axis ◽  
Electrically Conductive ◽  
Marine Propulsion ◽  
In Series ◽  
Physical Phenomena ◽  
Experimental And Theoretical Studies

Abstract Shortcomings of conventional propeller propulsion can theoretically be removed by using a modern technology - unconventional hydroelectromagnetic propeller or magnetohydrodynamic (MHD thruster), that highlights an application of great interest about physical phenomena that occur in the interaction between electromagnetic fields and electrically conductive fluids. In application to marine propulsion, investigations of a variety of physical phenomena was carried out, including the flow characteristics in a MHD duct, thrust efficiency and optimum shape of the duct. This paper presents related interaction phenomena between a magnetic induction, created by a d.c. electromagnet and d.c. current, perpendicular to the field, imposed by a voltage difference between two electrodes in the conductive sea water. The fluid is forced to the direction perpendicular to the plane where magnetic and electric fluxes are intersecting, this force is called the Lorentz force. Experimental and theoretical studies were carried out on small magnetohydrodynamic model (DC homopolar model) having two channels arranged in series or parallel. Each time the speed distribution was followed over the channel axis and perpendicular to channel axis.

Liquid Ejection Through Orifices by Sparging Gas: The PERCOLA Program

2002 ◽  
Author(s):  
B. Tourniaire ◽  
J. M. Seiler ◽  
J. M. Bonnet ◽  
M. Amblard
Keyword(s):  
Quantitative Information ◽  
Experimental Program ◽  
General Description ◽  
Water Pool ◽  
Qualitative And Quantitative ◽  
Main Target ◽  
Calculation Results ◽  
Core Meltdown ◽  
Cooling Mechanism ◽  
Physical Phenomena

Corium coolability after a severe PWR accident involving core meltdown and RPV failure is one of the main items in nuclear safety. The case considered here is a situation in which the corium is supposed to spread over a concrete floor and is flooded by water. In this frame, many researches are performed to study the physical phenomena which may enhance the heat transfer between the corium and the water pool. Among them, the melt entrainment above the corium crust by the sparging gas released by the concrete ablation appears as a potentially efficient cooling mechanism. The main target of the experimental program PERCOLA is to provide qualitative and quantitative information on this entrainment phenomenon. The first part of this paper is devoted to a general description of the experimental program and to the presentation of the main results. In a second part, the attention is focused on the modelling of the liquid entrainment phenomenon and to the comparison between the experimental data and the calculation results of two different entrainment models.

BTEX degradation in a cold-climate wetland system

2005 ◽  
Vol 51 (9) ◽  
pp. 165-171 ◽  
Author(s):  
S. Wallace ◽  
R. Kadlec
Keyword(s):  
Pilot Scale ◽  
Full Scale ◽  
Cold Climate ◽  
System A ◽  
Degradation Rates ◽  
Mass Load ◽  
Hydraulic Load ◽  
In Series ◽  
Benzene Toluene ◽  
Wetland System

A pilot-scale subsurface vertical-flow wetland system was constructed at the former BP Refinery in Casper, Wyoming in order to determine benzene, toluene, ethylbenzene and xylene (BTEX) degradation rates in a cold-climate application. The pilot system, consisting of 4 cells, each dosed at a nominal flow rate of 5.4 cubic metres per day, was operated between August and December 2002. The pilot tested the effects of wetland mulch and aeration on system performance. Areal rate constants (kA values) were calculated based on an assumed three tanks in series (3TIS). The presence of wetland sod and aeration both improved treatment performance. Mean kA values were 244 m/yr for cells without sod or aeration, and improved to 356 m/yr for cells with sod and aeration. Based on the results of the pilot system, a full-scale wetland system (capable of operating at 6,000 m3/day) was started up in May 2003. The full-scale system achieved permit compliance within one week of startup, but is currently being loaded at only 45% of the design hydraulic load, and 15% of the design BTEX mass load, resulting in a mean kA value of ∼350 m/yr.

Understanding the Hazards of Grouped Electrical Cables

2010 ◽  
Author(s):  
K. McGrattan ◽  
A. Lock ◽  
N. Marsh ◽  
M. Nyden ◽  
J. Dreisbach ◽  
...  
Keyword(s):  
Heat Release ◽  
Nuclear Regulatory Commission ◽  
Fire Spread ◽  
Quantitative Information ◽  
Full Scale ◽  
Small Samples ◽  
Experimental Program ◽  
Bench Scale ◽  
Regulatory Commission ◽  
Electrical Cables

CHRISTIFIRE (Cable Heat Release, Ignition, and Spread in Tray Installations during FIRE) is a U.S. Nuclear Regulatory Commission Office of Research program to quantify the mass and energy released from burning electrical cables. This type of quantitative information will be used to develop more realistic models of cable fires for use in fire probabilistic risk assessment (PRA) analyses. The experimental program has two main thrusts—bench-scale measurements of small samples of burning cables and full-scale measurements of the heat release and fire-spread rates of cables burning within typical ladder-type trays. The bench-scale measurements include micro-calorimetry of cable components, effluent characterization using absorption spectroscopy, and measurements of the heat release rate using a cone calorimeter. The full-scale measurements include the burning of a variety of cables within a typical tray under radiant panel heating, and full-scale, multiple tray fires. The outcome of the experiments is to be used by a variety of fire models, ranging from simple correlations to computational fluid dynamics.

scholarly journals A Multisensor System for the Characterization of the Field Pressure in Terrain. Accuracy, Response, and Adjustments

Sensors ◽  
2019 ◽  
Vol 19 (18) ◽  
pp. 3942
Author(s):  
Isabel Sicilia ◽  
Sofía Aparicio ◽  
Borja Frutos ◽  
Eduardo Muñoz ◽  
Margarita González ◽  
...  
Keyword(s):  
Concrete Slab ◽  
Pressure Sensors ◽  
Temporal Response ◽  
Generator System ◽  
Multisensor System ◽  
Motion System ◽  
Transport Studies ◽  
Real Model ◽  
In Series ◽  
Physical Phenomena

In different disciplines of science, the knowledge of the resulting pressures in the subsoil can help to understand physical phenomena of mass exchange between the atmosphere and the terrain. The measurement of lower differential pressures is complicated given the low range of detected values. In this paper, a multisensor system has been designed and developed to measure differential pressures in radon gas transport studies. The adequacy of this system has been proven using a purpose-built pressure chamber and an automatic motion system developed by the authors. The temporal response frequencies, the pressure values measured by the sensors, and their ability to link in series were analyzed to offer a multisensor spatial and temporal mapping. At the same time, the influence of the components required for a real deployment were studied using different tube lengths and diameters, connectors, and obstructions across the operating range of the pressure sensors. The system has also been tested for measuring differential pressures in a real model with a concrete slab above the soil and a pressure generator system below. It was found that this system is very suitable for outdoor measurements that demand a quick temporal response and accuracy.

Quantitative assessment of the removal of indicator bacteria in full-scale treatment plants

2004 ◽  
Vol 4 (2) ◽  
pp. 47-54 ◽  
Author(s):  
W.A.M. Hijnen ◽  
G.J. Medema ◽  
D. van der Kooij
Keyword(s):  
Quantitative Information ◽  
Average Concentration ◽  
Full Scale ◽  
Indicator Bacteria ◽  
Quantitative Microbial Risk Assessment ◽  
Water Recovery ◽  
Microbial Risk Assessment ◽  
Microbial Risk ◽  
Drinking Water Standard ◽  
Micro Organisms

The elimination of thermotolerant coliforms (Coli44) and spores of sulphite-reducing clostridia (SSRC) in full-scale water treatment was determined by large volume sampling. The objective was to determine the elimination capacity of full-scale treatment processes for micro-organisms, both vegetative bacteria and bacterial spores. In two short-periods in winter and summer, information was collected about the elimination of Coli44 and SSRC by the overall treatment, the contribution of the unit processes and the variability in elimination. Coli44 concentrations in the source waters were reduced by 3.2 to 6.3 log to an average concentration sufficiently low to achieve more than 99% compliance with the drinking water standard. The elimination of SSRC was lower (1.4 to 4.2) and SSRC were observed occasionally (>1%) in finished water by the routine weekly sampling of 100 ml samples. The study also yielded much information about the elimination efficacy of unit processes at the different locations, which enables process optimization and improved process control. Moreover, it is demonstrated that this quantitative information on removal of indicator bacteria by full-scale treatment systems can be used as input for quantitative microbial risk assessment. Further research will be focussed on comparative studies on the removal of faecal indicators and pathogens by unit processes and the improvement of the enumeration methods of pathogens in the source water (recovery efficiencies, specificity).

Optimisation and Uprating of Activated Sludge Plants by Efficient Process Design

1988 ◽  
Vol 20 (4-5) ◽  
pp. 121-132 ◽  
Author(s):  
B. Chambers ◽  
G. L. Jones
Keyword(s):  
Mathematical Model ◽  
Activated Sludge ◽  
Plug Flow ◽  
Oxygen Demand ◽  
Full Scale ◽  
Aeration Tank ◽  
Effluent Quality ◽  
Integration Techniques ◽  
In Series ◽  
The Uk

Requirements to improve effluent quality and reduce operating costs at existing activated sludge plants in the UK have led to the development of an accurate mathematical model of the process which can be used for full-scale design. The WRc Activated Sludge Model has been developed over a number of years and is based on the concept of describing the kinetics of BOD removal by including a Monod term for growth and a Michaelis-Menten term for enzymatic activity. Since the first formulation of the model, further equations have been added which describe the use of oxygen and nitrate as electron acceptors for the conversion of BOD. The model equations can be used to predict the performance of most configurations of the activated sludge process by using the ‘tanks in series' concept to describe aeration tank mixing characteristics. Solutions to the equations are easily obtained by standard numerical integration techniques using a computer. The software has been written in such a way that the model can be used interactively by a plant designer. Results obtained using the mathematical model have been used to redesign several full-scale activated sludge plants in the UK. In some cases, it has been possible to reduce the energy costs for aeration by 40% whilst maintaining effluent quality by accurately matching the supply of oxygen to the spatially-varying oxygen demand in plug-flow aeration tanks. Bulking sludge problems have also been solved by the conversion of completely-mixed aeration tanks to plug-flow aeration tanks with complementary redesign of the aeration system.

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