1,354,278 research outputs found
Isola dei Granai, Danzica
No full textPresentazione del progetto per la trasformazione dell'Isola dei granai in centro città, redatto da G. Polesello con i suoi allievi (R. Fein, M. El Daccache, A. Dal Fabbro, M. Iori, S. Maffioletti, M. Montuori, P. Valle) in occasione del Seminario internazionale organizzato dall'Ordine degli Architetti della Polonia, Danzica 1989
Innovative Approaches for Mapping the Pressurized Irrigation Systems Performances Under Unsteady Flow Conditions
No full textNowadays, the management of pressurized irrigation networks requires plenty of information to provide an efficient and reliable service to farmers. An approach called MASSPRES is being developed as a collaboration between FAO and CIHEAM-Bari with the goal of developing a reliable modernization strategy and improving the performance of pressurized irrigation systems. Mapping the perturbation, which is represented by the unsteady state flow analysis, is one of the most significant steps of this approach. The perturbation in irrigation networks is often created when sudden changes in flow rates occur in the pipes. This is essentially due to the manipulation of hydrants (service outlets) according the operational scenarios called configurations.
During the perturbation occurrence, pressure waves propagate through the networks pipes that may lead to a signification pressure variation. This variation could expose the irrigation system’s components to a substantial danger that could cause significant damage.
To model such a phenomenon, several computational algorithms have been developed. The majority of these models aimed to simulate the unsteady state conditions induced by the farmer’s behavior. The most recent ones are efficient enough to provide a good image of the perturbation occurrence through different indicators, however, one of the main draw backs of such model is the significantly high time and computational costs.
In the present work, two different generations of models were developed. The first is a directly programmed model that was devaloped based on the method of characteristics and two indicators have been introduced: i) The hydrant risk indicator (HRI), which is defined as the ratio between the participation probability of hydrant no. x in the riskiest configurations and its total number of participations; and ii) the relative pressure exceedance (RPE), which provides the variation of the unsteady state pressure with respect to the nominal pressure. The two indicators could help managers better understand the network behavior with respect to the perturbation by defining the riskiest hydrants and the potentially affected pipes.
Although, knowing the riskiest hydrants in the network is an important piece of information, managing ramified networks in real time will remain a difficult task to handle in real time. Thus, the need of developing a real time Decision Support System (RTDSS) that could process such information and guide the manager in real time is crucial.
For this aim, two thousand configurations (operational scenarios) were simulated using the directly programmed model from the first step and fed to train a new model based on deep learning with the objective of forecasting the maximum pressure occurred due to the perturbation at each section. The occurred pressure is represented as classes according to the case sensitivity and the required precision. Steps of 1, 2 and 3 bars were simulated. The model proved to be significantly time saving compared to previous approaches as the results are produced instantaneously with a forecasting accuracy of 85 %. Furthermore, using the confusion matrix, the error committed by the model is of one class lower or higher that may be considered tolerable according to the system sensitivity.
This approach was applied on a pressurized on-demand irrigation system located in south of Italy that consists of 19 hydrants and covers 57 hectares. Nonetheless, the deep learning-based model needs to be trained on each section. Thus, as a main step of the method of characteristics, the network was discretized into 1017 sections of 3 meter each. Training the deep learning model for such number of sections is not practical and time consuming. For this reason, a code was developed using autoencoding combined with t-distributed stochastic neighbor embedding (t-SNE) algorithm for features extraction and their visualization respectively. It is principally to cluster the sections according to their behavior to the perturbation, thus, reduce the number of trainings of the previously mentioned model. Nine zones of similar behavior were determined by the present developed code and the deep learning model will be trained only on these zones representing all the sections.
The two last developed codes could be integrated for a decision support system (DSS) for modelling the perturbation in the on-demand pressurized irrigation networks that would add a significant contribution to provide practical recommendations for real-time decision-making processes. which was not possible using directly programmed software
Assessing pressure changes in an on-demand water distribution system on drip irrigation performance - a case study in Italy
No full textThe hydrant pressure head in an on-demand water distribution system can be subject to high fluctuation depending on the discharge flowing inside the pipes, with consequent impacts on the performance of on-farm irrigation systems. In this work, an Italian water distribution system was analyzed using the AKLA model at upstream discharges of 1,200 and 600 L center dot s(-1) to estimate the range of hydrant pressure variation. A computer model was developed, calibrated, and used to evaluate the performance of a drip irrigation system by relating the on-farm network with the hydrant characteristic curve at a certain operating status. The flow regulator within the hydrant played an important role in stabilizing the performance of the network at hydrant pressures higher than 27 m. At lower hydrant pressures, to apply the same amount of water, irrigation time must be extended by 17 and 95% for pressure heads of 20 and 12 m, respectively. These approaches described have great utility to ensure adequate irrigation management when water is delivered by pressurized on-demand systems
On-demand pressurized water distribution system impacts on sprinkler network design and performance
No full textOn-farm irrigation networks are designed for optimum performance at a specific upstream pressure head. In pressurized water distribution systems operating on demand, the upstream pressure head of the on-farm network can be subject to high and continuous fluctuations depending on the number of the hydrants being simultaneously opened. In this paper, a methodology combining network design and performance analysis of a sprinkler network is described and applied to an irrigation distribution system operating at two different water demands (1,200 and 600 l s -1) using a case study in Italy. Four designs of the same sprinkler network were optimized at different upstream designing pressure and were evaluated at all the possible operating conditions of the system. The expensive large pipe size diameter design presented the best performance and the highest reliability at a wide range of hydrant pressure while the small pipe size designs have the tendency to fail during the peak water demand period as a result of low hydrant pressure. Flow regulators within the hydrants showed to have an important role in stabilizing the network performance at elevated upstream pressure head
SIM - Safe Irrigation Management V2.0
No full textSIM (Safe Irrigation Management) is a one-dimensional, daily water balance model designed for simulating soil moisture content under specific crop, soil, irrigation management, water quality and climatic conditions. The model contains 4 modules (Figure 1): i) crop water demand and irrigation scheduling module, ii) salinity management module, iii) bacterial movement and risk assessment module and v) nutrient management module
On-farm Sprinkler Irrigation Performance as affected by the Distribution System
No full textIn this paper, the influence of the pressurised distribution irrigation system on the performance of the on-farm sprinkler network is analysed. The pressure values at the hydrants were calculated by means of a stochastic simulation model using a random procedure to generate a large number of different operating conditions. An iterative model was developed for generating the characteristic curve of the on-farm sprinkler irrigation network. The pressure variation downstream of the hydrant was computed by intersecting the characteristic curve of the latter with the generated on-farm characteristic curve. A detailed performance analysis was carried out on an existing irrigation system.
This study highlighted that the performance of the on-farm sprinkler network is greatly affected by the variation in the hydrant pressure head
Closure to “Assessing Pressure Changes in an On-Demand Water Distribution System on Drip Irrigation Performance—Case Study in Italy”
No full textIgnace Antoine II Hayek, "Le relazioni della Chiesa Siro-giacobita con la Santa Sede dal 1143 al 1656"
No full textEdizione della tesi di dottorato di A. Hayek (1936
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Climate change and the performance of pressurized irrigation water distribution networks under mediterranean conditions: Impacts and adaptations
No full textNumerous previous studies have modelled the impact of climate change on crop
water requirements and hence future water resource needs for irrigated
agriculture. Fewer have considered the impacts on the performance of irrigation
systems and the required engineering and managerial adaptations. This study
considers the impacts and adaptations for a typical pressurized pipe irrigation
system. The dry years of the baseline period (1970-90) in the southern part of
Italy are expected to become the average or even wet year by the 2050s,
according to HadCM3 projections. Under these conditions, the large water
distribution systems designed to satisfy the baseline dry years will fail unless
appropriate engineering or managerial adaptations are made. The resilience of
District 8 of the Sinistra Ofanto to the possible future increase in irrigation
demand has been assessed. A stochastic weather generator was used to generate
future weather under the IPCC A1 and B1 emissions scenarios, taking into
consideration the outputs of the HadCM3 model. A daily water balance model was
used to quantify the actual and future peak water demand of the district. The
reliability of each hydrant under baseline and future demand was calculated
using a stochastic hydraulic model and the failure zones identified. Under the
current design, the system can tolerate a peak demand discharge up to 1,500 l.s
(-1), which is below the 2050s' average (1,720 l.s(-1)). Above that value, the
performance of the system will fall drastically as the number of unreliable
hydrants will increase. In the future, assuming the same cropping pattern, the
threshold discharge (1,500 l.s(-1)) will be exceeded 80% of the time and, as an
average, 20% of the system's hydrants will be failing during the peak demand
periods. The adaptation options available to farmers and system managers in
response to the increasing demand are discussed
- …
