Search results for "Science and technology"

Two-Dimensional Numerical Modelling of a Moored Floating Body under Sloping Seabed Conditions

2020

A coupled floating body-mooring line model is developed by combining a boundary element model for a two-dimensional floating body and a catenary mooring line model. The boundary element model is formulated in the time domain by a continuous Rankine source, and a reflection potential is introduced to account for the wave reflection due to sloping seabed. This newly developed model is validated by comparisons against available data. Then, dynamic response analyses are performed for the moored body in various seabed conditions. Compared with a flat seabed, a sloping seabed causes unsymmetrical mooring line configuration and generates noticeable effects in the motion responses of the floating b…

Dynamic goal programming synthetic indicator: an application for water companies sustainability assessment

2018

ABSTRACTThis study proposes to evaluate the sustainability of water companies through time by using a new approach, one that involves a dynamic synthetic indicator derived from goal programming techniques. This dynamic indicator approach incorporates catch-up and innovation indices, which enables one to identify the main factors that drive changes in sustainability through time. We used a case study approach to clarify this dynamic approach by evaluating indicator values from a sample of 129 Portuguese water companies over the 2012 to 2015 time period. For most of the water companies we evaluated, sustainability values changed over time, which illustrates the importance of evaluating dynami…

Optimization of photovoltaic solar power plant locations in northern Chile

2017

The optimization of photovoltaic solar power plants location in Atacama Desert, Chile, is presented in this study. The study considers three objectives: (1) Find sites with the highest solar energy potential, (2) determine sites with the least impact on the environment, and (3) locate the areas which produce small social impact. To solve this task, multi-criteria decision analyses (MCDAs) such as analytical hierarchy process and ordered weighted averaging were applied in a GIS environment. In addition, survey results of social impacts were analyzed and included into the decision-making process, including landscape values. The most suitable sites for solar energy projects were found near roa…

Linking the Kinetic Energy Fraction and Equivalent Length Method for Trickle Irrigation Design under Local Losses

2020

New methods using analytical relationships to design drip irrigation laterals and subunits have been introduced in recent years based on the assumption that minor losses can be neglected. This assumption could be relaxed by applying the equivalent method, which makes it possible to account for minor losses, such as those caused by emitter connections, through formulas based on the rationale that an equivalent length of the drip lateral produces the same losses. However, equivalent length formulas are empirical; thus, they do not necessarily cover the entire range of conditions in the real-world contexts in which the formulas will be applied, and their extrapolation could lead to erroneous r…

Experimental study and numerical simulation of inclined rectangular weirs

2018

Inclined rectangular weirs, also named pivot weirs, are used both to adjust the upstream water level and to increase the flow capacity compared with that of normal rectangular weirs. However, the experimental studies available in the literature present contradictory conclusions for the inclined weir discharge capacity. In this paper, new experimental runs and numerical simulations were performed to investigate the effect of the rectangular weir inclination angle on the stage-discharge formula. The experiments were carried out using inclination angles ranging from 30° to 90°. Buckingham's theorem of dimensional analysis was used to obtain an equation for the flow magnification ratio (the dis…

Discussion of "extraction of the flow rate equation under free and submerged flow conditions in pivot weirs with different side contractions" by N. S…

2018

This paper is the discusison of the paper "Extraction of the flow rate equation under free and submerged flow conditions in pivot weirs with different side contractions" by N. Sheikh Rezazadeh Nikou, M. J. Monem, and K. Safavi.

Soil genetic erosion: New conceptual developments in soil security

2019

In the last decades, in some Mediterranean areas, pedodiversity decreased mainly due to pedotechnique application in large-scale farming that transformed original soils into Anthrosols. Supporting the consideration that soils can be considered as living systems, the original concept of 'soil genetic erosion' is re-proposed. Data, extrapolated and modeled from a Soil Information System in a study case representative of a Mediterranean landscape, predicted that most of the soil types would disappear in few years leading to a decrease of the soil diversity and originating soil genetic erosion. This circumstance is intentionally here told in form of a story where the fairy tale characters are s…

Waste activated sludge dewaterability: comparative evaluation of sludge derived from CAS and MBR systems

2016

Nowadays, sludge dewatering is one of the greatest operational cost to wastewater treatment cycle. Specifically, 1t of fresh sludge to be disposed is composed, on average, by 0.25 - 0.30t of suspended solids, with an average cost for treatment and disposal around 280 - 470 €/t of suspended solids. Despite several technologies have been developed with the focus to reduce also the specific sludge production, still mechanical dewatering represents a crucial step to limit the amount of sludge to be disposed. Many physical–chemical parameters influence the sludge dewaterability: floc structure, particle size, bound water content, surface charge and hydrophobicity, Extracellular Polymeric Substan…

Closure to “Extraction of the Flow Rate Equation under Free and Submerged Flow Conditions in Pivot Weirs with Different Side Contractions” by N. Shei…

2018

Financial winners and losers since the privatization of the English and Welsh water and sewerage industry: a profit decomposition approach

2020

Evaluating changes in profit, price and productivity over time can be of great importance for regulated water industries. We investigate the drivers of profit, price (capital, labour and other inputs) and productivity change (cost efficiency change, technical change and scale effect) and the recipients of productivity change (consumers, the business itself, employees and other resource suppliers) of the English and Welsh water and sewerage companies over the period of 1995–2016. The results indicate that the profit decreased over time due to the negative quantity effect, which offset the positive price effect. A further decomposition of the quantity effect illustrates the negative impact of…