680 research outputs found

    Neural Network Modelling of Tds Concentrations in Shatt Al-Arab River Water

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    River water salinity is a big concern in many countries, considering agricultural and drinking usages. Therefore, prediction of amount of Total Dissolved Solid (TDS) is a necessary tool for planning and management of water resources. Shatt Al-Arab river basin in Basrah which is located in south of Iraq suffer from high salinity, therefore use of the water for irrigation and drinking has become problematic. In this regard, prediction of future TDS of Shatt Al-Arab river basin was studied using Artificial Neural Network (ANN). Data measured monthly from January 2007 up to December 2012 at monitoring station in the middle point along to the Shatt Al-Arab river has been used for training of the selected ANN. Some of water quality parameters such as, power of hydrogen (pH), Total Hardness (TH), Magnesium hardness (MgSO4), Calcium hardness (CaSO4), Chlorides (Cl), Sulphates (SO4), turbidity (TU) and electrical conductivity (EC) were considered as inputs for the ANN and Total Dissolved Solid (TDS) was the output of the model. The validation of the neural network model showed very good agreement for predictions of the TDS concentrations between observed and simulated values. The coefficient of correlation (R), during the validation process was found to be (1), and the mean squared error (MSE) was (0.075). This work supports the concept that the neural network approach is a successful method of modelling such complex and nonlinear behavior of TDS in the rivers with different environmental conditions

    Impact of Clustering Microgrids on Their Stability and Resilience during Blackouts

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    In this paper, the impact of clustering multiple microgrids during blackouts, on their stability and supply availability, will be investigated. Microgrids have the capability of satisfying their emergency loads during blackouts. However, distributed energy resources (DERs)-dominated microgrids are affected by the uncertainty of their input energy supply, e.g. impact of solar irradiance on photovoltaic (PV) output. Moreover, an individual islanded microgrid is prone to instability issues due to large sudden load/generation changes. In order to increase the supply security, and enhance system stability, we propose to use the existing distribution grid infrastructure, if applicable, during blackouts to form microgrid clusters. The paper discusses the required control hierarchy required to manage the microgrid clusters, and communicate with the Distribution Network Operator (DNO). A case study based on the 13-bus standard distribution feeder, and two microgrid models, is presented. Results show that microgrids clustering helps improve their performance and that the microgrid generator inertia has a direct impact on the stability of the microgrid cluster

    Intelligent Optimization Systems for MaintenanceScheduling of Power Plant Generators

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    This paper presents a Genetic Algorithm (GA) and Ant-Colony (AC) optimization model for power plant generators’ maintenance scheduling. Maintenance scheduling of power plant generators is essential for ensuring the reliability and economic operation of a power system. Proper maintenance scheduling prolongs the shelf life of the generators and prevents unexpected failures. To reduce the cost and duration of generator maintenance, these models are built with various constants, fitness functions, and objective functions. The Analytical Hierarchy Process (AHP), a decision-making tool, is implemented to aid the researcher in prioritizing and re-ranking the maintenance activities from the most important to the least. The intelligent optimization models are developed using MATLAB and the developed intelligent algorithms are tested on a case study in a coal power plant located at minjung, Perak, Malaysia. The power plant is owned and operated by Tenaga Nasional Berhad (TNB), the electric utility company in peninsular Malaysia. The results show that GA outperforms ACO since it reduces maintenance costs by 39.78% and maintenance duration by 60%. The study demonstrates that the proposed optimization method is effective in reducing maintenance time and cost while also optimizing power plant operation

    Left atrial and left atrial appendage functional recovery after cardioversion in patients with recent atrial fibrillation: Serial echocardiographic study

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    Background: The aim of this study is to point out timing of left atrium and its appendage functional recovery after cardioversion (CV) in recent onset atrial fibrillation (AF). Methods: Fifty patients; 27 within 48-h (group I) and 23 after 48-h (group II), of AF onset, who had successful CV underwent transthoracic echocardiography (TTE), before and im­mediately after CV, then 15, 30 and 90 days later. Transesophageal echocardiography (TEE) was performed for group II before and for all patients immediately after CV and 1 month later. Mitral peak A velocity and left atrial (LA) reversal (Ar) velocity, tissue Doppler imaging (TDI) of septal mitral annular velocity (A1) and LA free wall velocity (A3) were recorded. Absence or peak A velocity < 50 cm/s was taken as a cut off value for atrial stunning. Intra-atrial conduction time (IACT) was measured. LA appendage late emptying (LAALE) velocity was measured by TEE-pulsed TDI of LA appendage. Results: Post CV, all group II and 34% of group I experienced stunning. In both groups, peak A, Ar, A1, A3 and LAALE velocities increased (p = 0.000), while IACT decreased (p = 0.000) progressively over time. Partial recovery occurred after 15 and 30 days, while full recovery occurred 30 and 90 days post CV in groups I and II, respectively. IACT1 and IACT2 correlated with LA diameter (r = 0.2778 and r = 0.227, respectively, p < 0.01). Conclusions: Stunning and functional recovery of the LA and its appendage are strongly determined by the duration being in AF. Serial IACT by TDI was a good new parameter for detection of functional recovery of LA and LA appendage

    PERFORMANCE ANALYSIS OF OPTICAL CDMA SYSTEM USING VC CODE FAMILY UNDER VARIOUS OPTICAL PARAMETERS

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    The intent of this paper is to study the performance of spectral-amplitude coding optical code-division multiple-access (OCDMA) systems using Vector Combinatorial (VC) code under various optical parameters. This code can be constructed by an algebraic way based on Euclidian vectors for any positive integer number. One of the important properties of this code is that the maximum cross-correlation is always one which means that multi-user interference (MUI) and phase induced intensity noise are reduced. Transmitter and receiver structures based on unchirped fiber Bragg grating (FBGs) using VC code and taking into account effects of the intensity, shot and thermal noise sources is demonstrated. The impact of the fiber distance effects on bit error rate (BER) is reported using a commercial optical systems simulator, virtual photonic instrument, VPITM. The VC code is compared mathematically with reported codes which use similar techniques. We analyzed and characterized the fiber link, received power, BER and channel spacing. The performance and optimization of VC code in SAC-OCDMA system is reported. By comparing the theoretical and simulation results taken from VPITM, we have demonstrated that, for a high number of users, even if data rate is higher, the effective power source is adequate when the VC is used. Also it is found that as the channel spacing width goes from very narrow to wider, the BER decreases, best performance occurs at a spacing bandwidth between 0.8 and 1 nm. We have shown that the SAC system utilizing VC code significantly improves the performance compared with the reported codes

    Artesunate plus sulfadoxine-pyrimethamine for treatment of uncomplicated Plasmodium falciparum malaria in Sudan

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    BACKGROUND: Early diagnosis and effective treatment with an appropriate drug form the main components of the World Health Organization's strategy to reduce malaria related mortality. The few available drugs might be safeguarded if combined with artesunate. The addition of artesunate to a standard antimalarial treatment substantially reduces treatment failure, recrudescence and gametocyte carriage. METHODS: During late 2004, the efficacy of artesunate (4 mg/kg. day, on days 0–2) plus sulfadoxine-pyrimethamine (25 mg/kg, on day 0) for the treatment of uncomplicated Plasmodium falciparum malaria was investigated in four sentinel areas in Sudan, with different malaria transmission (Damazin, Kassala, Kosti, and Malakal). RESULTS: Two hundreds and sixty-nine patients completed the 28-day follow-up. On day one, 60 (22.3%) patients were febrile and 15 (5.5%) patients were parasitaemic. On day three, all the patients were afebrile and aparasitaemic. While two patients (0.7%, Kassala) showed late Clinical and Parasitological Failures, the rest (99.3%) of the patients demonstrated Adequate Clinical and Parasitological Response. A gametocytaemia were detected during the follow-up in one patient (0.37%, Kassala). Adverse drug effects were detected in 32 (11.9%) patients CONCLUSION: The study showed that AS plus SP is an effective, safe drug in the treatment of uncomplicated P. falciparum malaria in Sudan

    Spectrophotometric study on reaction of non-naturally haem proteins with thiols in aqueous solutions .

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    Spectrophotometric titrations of dilute solution of tetra (p-sulphonaphthyl) porphinato Iron (II) [ TNPS4 Fe (II) ] in the presence of a large excess of thiols at high (PH=12.8) were studied. Evidence for high spin five coordinate iron (II) complexes were found . Thermodynamic parameters and stability constants , refer to exothermic reaction with negative values of ∆H and ∆G. LogKF , Log KD and (n) number of bounded ligands were calculated , and found to be (n=1-1.3) , which were assigned to five and six coordinate to the iron (II) atom. These results are discussed in relation to the high spin iron (II) state in the catalytic cycle of cytochrome (p-450

    Laminectomy versus interlaminar approach for Lumbar disc herniation

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    Background: Low back pain is the most common health problem in men and women between the ages of 20 and 50 years. The lumbar disc prolapse has a major role in this condition. Treatment is either conservative or surgical. The most common surgical interventions are either laminectomy or interlaminar approach. Objective: To determine which is the best surgical approach for the patient according to his/her type of disc herniation. Patients and methods: A comparative clinical study conducted in the Neurosciences Hospital, Baghdad, Iraq from January 2016 to January 2018. In this paper we evaluated the clinical outcome following both approaches Results: We studied sixty cases; thirty-four patients had interlaminar approach for lumbar discectomy while twenty-six patients had laminectomy with discectomy. Conclusion: Both methods can manage different types of lumbar disc prolapse, apart from far-lateral disc which favors laminectomy approach

    Viridiflorol Induces Anti-Neoplastic Effects on Breast, Lung, and Brain Cancer Cells Through Apoptosis

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    All active natural molecules are not fully exploited as therapeutic agents, causing delays in the advancement of anticancer drug discovery. Viridiflorol is a natural volatile element that may work as anti-cancer compound. We tested the anticancer properties of viridiflorol at different concentrations ranging from 0.03 to 300 ΌM in vitro on three cancer cells including breast (MCF-7), lung (A549) and brain (Daoy). The cancer cells responses were documented after treatment using MTT and Annexin V assays. Viridiflorol showed cytotoxic effects against all tested cell lines, reducing cell viability in a concentration-dependent manner with variable IC50 values. Daoy and A549 cell lines were more sensitive to viridiflorol when compared with temozolomide and doxorubicin, respectively. Viridiflorol demonstrated the highest anticancer activity against the Daoy cells with an estimated IC50 of 0.1 ”M followed by MCF-7 at 10 ”M, and A549 at 30 ”M. In addition, upon exposure to concentrations ranging from 30 ”M to 300 ”M of viridiflorol, early and late apoptotic cell death was induced in a concentration dependent manner in Daoy (55.8%-72.1%), MCF-7 (36.2%-72.7%) and A459 (35%-98.9%) cell lines, respectively. In conclusion, viridiflorol demonstrates cytotoxic and apoptotic ability in three different cancer cell lines (brain, breast and lung)
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