Studying Structural Behavior of Concrete Faced Rockfill Dam Using Finite Element Method

Concrete faced rock fill dam has been increasingly popular among dam engineers due to their inherent advantages over other type of dams. The construction of concrete faced rockfill dam has been conducted in full swing in recent years. But still there is some crucial problems needed further investigation. In this study an attempt has been made to investigate various aspects related to the structural analysis of concrete face rockfill dams, this involved, physical modelling, constitutive modelling, effect of concrete slab and simulation of sequence of construction. To model sequential stages of construction of concrete faced rockfill dam the Dead- Birth-Ghost element technique was used. The physical modeling was carried out using finite-infinite elements to represent bedding media, eight and six noded isoparametric elements were used for modeling the dam body and the concrete face respectively. Moreover the interfacial behavior between the concrete face and the body of the dam was modeled using interface element. The constitutive modeling has body of the dam was modeled using interface element. The constitutive modeling has been accounted by employing the hyperbolic nonlinear elastic model. So based on the above physical and material modeling a two dimension linear and nonlinear finite element program with different type of isoparametric elements was written. The verification of the program was well established by analyzing certain bench mark examples. The applicability of the above program has been illustrated by analyzing two concrete faced rockfill dam namely; Kavar dam currently under construction in Iran (53.5 m), and Bakun dam currently under construction in the state of Sarawak Malaysia (205 m). The results indicates that the sequences of construction, reservoir filling and nonlinear material behavior have significant effects on the structural response of the dam in terms of displacement and stresses and need to be considered for accurate prediction of the structural behavior of the dam and focuses on the effect of face slab on the distribution of deformation and stresses developed due to the static loading including gravitation and reservoir loading

Phytotoxicity of <em>Plantago major</em> Extracts on Germination and Seedling Growth of Purslane (<em>Portulaca oleracea</em>)

Plantago major L. (Plantaginaceae family) has been used as herbal remedies for centuries in almost all over the world and in the treatment of a number of diseases. This study aims to assess the allelopathic potential of Plantago major extracts on the germination and early seedling growth of purslane. Total phenols, tannins, saponins, flavonoids, and alkaloids were determined in P. major. Furthermore, concentrations of 2.5, 5, 10, 20, and 40 mg.ml−1 of both alcoholic and aqueous extracts were prepared to study their phytotoxic effect on the germination and seedling growth of Portulaca oleracea weed. In our study, showing the germination of P. oleracea was completely inhibited (96.30 mg.ml−1) under treatment of P. major methanolic extracts at 40 mg ml−1. Moreover, both radicle and plumule were strongly inhibited (87.20 and 74.29 mg.ml−1, respectively) under the same treatment. This could be attributed to the high content of bioactive constituents. Therefore, this species can be used in the method of biological control of weeds. In addition, further studies are required to identify and characterize the proper allelochemicals and demonstrate their modes of action

Design and economic evaluation of solar-powered hybrid multi effect and reverse osmosis system for seawater desalination

YesReducing the cost of fresh water has always been a major concern in the desalination industry. A solar powered hybrid multi-effect distillation and reverse osmosis desalination plant (MED+RO) has been designed and optimised from an economical point of view in a previous work by the same authors. In the present study, the possibility of coupling the desalination plant with a photovoltaic (PV) solar farm is investigated, with the aim of generating electricity at low cost and in a sustainable way. A detailed mathematical model for the PV system has been implemented from the literature. Interestingly, the model can predict the cost of the PV system in terms of capital cost and electricity cost per kWh considering the input data of solar irradiation, duration of daylight and technical specification of a real solar module. Consequently, the solar PV model has been combined with the desalination model, which enables to estimate the cost of fresh water per cubic meter. Data about four locations, namely Isola di Pantelleria (IT), Las Palmas (ES), Abu Dhabi (UAE), and Perth (AUS), have been used to economically test the feasibility of installing the proposed plant, and especially of the PV solar farm

Cost evaluation and optimisation of hybrid multi effect distillation and reverse osmosis system for seawater desalination

YesIn this research, the effect of operating parameters on the fresh water production cost of hybrid Multi Effect Distillation (MED) and Reverse Osmosis (RO) system is investigated. To achieve this, an earlier comprehensive model developed by the authors for MED + RO system is combined with two full-scale cost models of MED and RO processes collected from the literature. Using the economic model, the variation of the overall fresh water cost with respect to some operating conditions, namely steam temperature and steam flow rate for the MED process and inlet pressure and flow rate for the RO process, is accurately investigated. Then, the hybrid process model is incorporated into a single-objective non-linear optimisation framework to minimise the fresh water cost by finding the optimal values of the above operating conditions. The optimisation results confirm the economic feasibility of the proposed hybrid seawater desalination plant

Multiplateau structure in photoemission spectra of strong-field ionization of dense media

Strong-field ionization of dense molecular gases in a short infrared laser pulse is studied by means of photoelectron spectroscopy combined with a liquid microjet technique. By increasing the gas density, we observe how the laser- assisted electron scattering on neighboring particles becomes a dominant mechanism of hot electron emission. The angle-resolved energy distributions of rescattered electrons are obtained by analyzing the density dependency of emission spectra. A semiclassical consideration of electron trajectories is shown to provide a good description of experimental spectra. The model predicts the existence of four energy plateaus. Two cutoffs at higher energies are evident in the spectra

Iraqi refugees in Egypt: an exploration of their mental health and psychosocial status

Thousands of Iraqis have settled in Egypt since 2003, escaping death threats, torture, kidnappings and military attacks to face uncertainty in their lives and increasing strain on the psychosocial challenges in their new lives. This explorative study describes the psychosocial stress faced by these Iraqi refugees in Egypt. Two hundred and four Iraqis in Egypt ¢lled in a checklist focussing on four groups of stress factors.The data provided by this study demonstrate the contribution of violence to Iraqi refugees&apos;life from a number of sources. More than 56% have experienced multiple traumatic situations before immigration and the refugees themselves report major impacts on their health, mental health and socioeconomic demands. A motivated desire to return home was preferred by only one third of respondents

How to better exploit the use of LCA analysis for Ultra High Performance Concrete (UHPC) through a constitutive law which integrates chloride and sulfate attack

Structural applications of advanced cementitious materials such as Ultra High Performance Concrete (UHPC) have been already assessed in harsh exposure conditions with presence of chlorides or sulfates. Nevertheless, the limited availability of design standards has not favoured so far a widespread use of these materials. Moreover, previous studies employed a constitutive model only partially representative of the real behavior of such materials when exposed to aggressive conditions. Therefore, this work, employing a “scenario dependent” constitutive law, estimates the serviceability limit state in correspondence of which it is needed to carry out the maintenance activities and investigates, through the Life Cycle Assessment (LCA) methodology, the ecological and economic profile of a UHPC water basin structure subjected to chloride and sulfate attack. The CML impact assessment method has been employed for the specific purpose to compare such structure to one made with ordinary reinforced concrete (ORC) using as system boundary the A1-B7 stages indicated in EN 15804

Magnetic resonance imaging findings in children with Parry-Romberg syndrome and en coup de sabre

BACKGROUND: The aim of this study was to: (i) describe the abnormalities seen on brain imaging in a group of children with en coup de sabre (EDCS) with/without Parry-Romberg syndrome (PRS); and (ii) identify clinical predictors of brain imaging abnormalities. METHODS: This was a single centre (Great Ormond Street Hospital, London) retrospective case series of patients with ECDS/PRS seen from 2000 to 2018. We identified patients with cutaneous manifestations consistent with the clinical descriptions of ECDS/PRS. Presenting clinical, laboratory, and radiological brain findings are described. Results are expressed as medians and ranges or frequencies and percentages. Fisher's exact test was used to identify clinical associations with magnetic resonance imaging (MRI) abnormalities. RESULTS: Fourteen patients were studied: 6 males and 8 females; median age 14 years (range 3-20). We observed neuroimaging abnormalities in 2/6 ECDS and 5/8 ECDS/PRS patients. White matter signal abnormality, dystrophic calcification, leptomeningeal enhancement, and sulcal crowding were the typical findings on brain imaging. A total of 50% of patients had no MRI abnormality despite some of these patients having neurological symptoms. The presence of seizures was significantly associated with ipsilateral enhanced white matter signalling on MRI (p < 0.05). CONCLUSIONS: In summary, we observed several distinct radiographic patterns associated with ECDS/PRS. Seizure disorder was strongly associated with the presence of ipsilateral enhanced white matter signalling. Improved neuroimaging techniques that combine morphological with functional imaging may improve the detection rate of brain involvement in children with ECDS/PRS in the future

The effect of blade angles of the vertical axis wind turbine on the output performance.

There are many social, political and environmental issues associated with the use of fossil fuels. For this reason, there are numerous investigations currently being carried out to develop newer and renewable sources of energy to alleviate energy demand. Wind is one source of energy that can be harnessed using wind turbines. In this study, numerical investigations using CFD analysis have been carried out to determine the optimum dimensions of a wind turbine used in urban environments by varying the rotor and stator blade angles. The effect of these blade angles have been considered to be within the normal operating range (α from 1.689 to 21.689 , δ from 22.357 to 42.357 and γ from 18.2 to 38.2 ) while β was kept constant to 90 . The results show that as α increase torque output and power output increases to a certain point after which both these quantities start decreasing. On the contrary to α, as δ increase torque output and power output decreases. From the results it can be concluded that the ideal blade angles, for optimal power output, are α=16.689, γ=18.2 and δ=22.357

Performance analysis of hybrid system of multi effect distillation and reverse osmosis for seawater desalination via modeling and simulation

YesThe coupling of thermal (Multi Stage Flash, MSF) and membrane processes (Reverse Osmosis, RO) in desalination systems has been widely presented in the literature to achieve an improvement of performance compared to an individual process. However, very little study has been made to the combined Multi Effect Distillation (MED) and Reverse Osmosis (RO) processes. Therefore, this research investigates several design options of MED with thermal vapor compression (MED_TVC) coupled with RO system. To achieve this aim, detailed mathematical models for the two processes are developed, which are independently validated against the literature. Then, the integrated model is used to investigate the performance of several configurations of the MED_TVC and RO processes in the hybrid system. The performance indicators include the fresh water productivity, energy consumption, fresh water purity, and recovery ratio. Basically, the sensitivity analysis for each configuration is conducted with respect to seawater conditions and steam supply variation. Most importantly, placing the RO membrane process upstream in the hybrid system generates the overall best configuration in terms of the quantity and quality of fresh water produced. This is attributed to acquiring the best recovery ratio and lower energy consumption over a wide range of seawater salinity