This paper presents the development of an optimized fuzzy logic controller (FLC) for operating a standalone hybrid power system based on cuckoo search algorithm. The FLC inputs are batteries state of ...charge (SOC) and net power flow, FLC outputs are the power rate of batteries, photovoltaic and diesel generator. Data for weekly solar irradiation, ambient temperature and load profile are used to tune the proposed controller by using cuckoo search algorithm. The optimized FLC is able to minimize loss of power supply probability (LPSP), excess energy (EE) and levelized energy cost (LEC). Moreover, the results of CS optimization are better than of particle swarm optimization PSO for fuzzy system controller.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK
In this paper, a mathematical model based on energy analysis, has been developed for modeling and simulation of solar tower power plants (STPP) performances without energy storage. The STPP system ...has been divided into four main subsystems: the heliostat field subsystem, the cavity receiver subsystem (tower), the steam generation subsystem and the power cycle subsystem (Rankine cycle). Thermal and thermodynamic models of main subsystems have been developed. A general nonlinear mathematical model of the studied system (STPP) has been presented and solved using numerical optimization methods. The obtained results are presented and analyzed. The effects of the receiver surface temperature and the receiver surface area on the cavity receiver efficiency and the steam mass flow have been investigated. The effects of other parameters, such as the incident heat flux, the absorbed energy and the heat losses from the receiver are also studied. The analysis of these results shows the existence of an optimal receiver efficiency value for each steam mass flow, receiver surface temperature and receiver surface area.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK
Proton Exchange Membrane (PEM) Electrolysers (ELSs) are considered as pollution-free with enhanced efficiency technology. Hydrogen can be easily produced from different resources like biomass, water ...electrolysis, natural gas, propane, and methanol. Hydrogen generation from water electrolysis, which is the splitting of water molecules into hydrogen and oxygen using electricity, can be beneficial when used in combination with variable Renewable Energy (RE) technologies such as solar and wind. When the electricity used for water electrolysis is produced by a variable RE source, the hydrogen stores the unused energy for a later use and can be considered as a renewable fuel and energy resource for the transport and energy sectors.
This paper aims to propose a novel graphical model design for the PEM-ELS for hydrogen production based on the electrochemical, thermodynamical and thermal equations. The model under study is experimentally validated using a small-scale laboratory electrolyser. Simulation results, using Matlab-Simulink™, show an adequate parameter agreement with those found experimentally. Therefore, the impact of the different parameters on the electrolyser dynamic performance is introduced and the relevant analytical-experimental comparison is shown. The temperature effect on the PEM-ELS dynamic behaviour is also discussed.
•State of the art of PEM-ELS modelling and experimentation.•Novel PEM-ELS graphical model design based on electrochemical, thermodynamical and thermal equations.•Experimental validation of the PEM-ELS using small-scale laboratory electrolyser.•Analytical-experimental comparison for PEM-ELS dynamic behaviour considering temperature effect.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Abstract Ankle brachial index (ABI) is a simple method to screen peripheral arterial disease (PAD) and to evaluate cardiovascular (CV) prognosis in the general population. Measuring it requires a ...hand-held Doppler probe but it can be done also with an automatic device. ABI is an effective tool for clinical practice or clinical studies. However, in diabetic patients, it has some specific caveats. Sensitivity of the standard threshold of 0.9 appears to be lower in diabetic patients with complications. Moreover, highly frequent arterial medial calcifications in diabetes increase ABI. It has been demonstrated that measurements >1.3 are well correlated with both an increased prevalence of PAD and CV risk. Therefore, ABI thresholds of less than 0.9 and more than 1.3 are highly suspicious for PAD and high CV risk in diabetic patients. However, when there is concomitant clinical peripheral neuropathy or high risk of arterial calcification, the efficiency of ABI seems to be limited. In this case, other methods should be applied, toe pressure, in particular. Thus, the ABI could be used in patients with diabetes, but values should be interpreted with precision, according to the clinical situation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Performance of power plant with molten salt cavity receiver is assessed.•A method has been used to optimize the plant solar multiple, capacity factor and LEC.•Comparison of the simulated results to ...those of PS20 has shown good agreement.•Higher fossil fuel fraction reduces the LEC and increases the capacity factor.•Highland and Sahara regions are suitable for CRS plants deployment.
Of all Concentrating Solar Power (CSP) technologies available today, the molten salt solar power plant appears to be the most important option for providing a major share of the clean and renewable electricity needed in the future. In the present paper, a technical and economic analysis for the implementation of a probable molten salt cavity receiver thermal power plant in Algeria has been carried out. In order to do so, we have investigated the effect of solar field size, storage capacity factor, solar radiation intensity, hybridization and power plant capacity on the thermal efficiency and electricity cost of the selected plant. The system advisor model has been used to perform the technical performance and the economic assessment for different locations (coastal, highland and Sahara regions) in Algeria. Taking into account various factors, a method has been applied to optimize the solar multiple and the capacity factor of the plant, to get a trade-off between the incremental investment costs of the heliostat field and the thermal energy storage. The analysis has shown that the use of higher fossil fuel fraction significantly reduces the levelized electricity cost (LEC) and sensibly increases the capacity factor (CF). The present study indicates that hybrid molten salt solar tower power technology is very promising. The CF and the LEC have been found to be respectively of the order of 71% and 0.35$/kWe. For solar-only power plants, these parameters are respectively about 27% and 0.63$/kWe. Therefore, hybrid central receiver systems are really attractive solutions for rapid deployment of CSP technology in Algeria.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK
Objective Cushing’s disease (CD) may recur despite corticotropic insufficiency (COI) following pituitary surgery. The predictive value of the desmopressin test (DT) for recurrence in this setting ...remains controversial. We have evaluated whether the disappearance of the response to DT predicts a low probability recurrence in a large cohort of patients with post-operative COI. Design Multicentre retrospective study. Methods Ninety-five patients with CD (women 82%, age 41 ± 14 years), responding preoperatively to DT and with early post-operative COI (08 00 am cortisol: <138 nmol/L), underwent a DT within 3 months post-surgery. Association between DT findings and the prediction of recurrence was tested using regression and ROC analyses. Results Recurrence occurred in 17/95 patients within 29 to 91 months. The cortisol peak (327, 95% CI (237–417) vs 121 (79–164) nmol/L, P = 0.0001) and absolute increment during DT (208 (136–280) vs 56 (22–90) nmol/L, P = 0.005) were greater in the recurrence vs remission group. Cortisol peak (AUC: 0.786 (0.670–0.902)) and increment (0.793 (0.672–0.914)) yielded a higher prognostic performance for recurrence than did the early post-operative 08 00 am cortisol (0.655 (0.505–0.804)). In the context of COI, cortisol peak >100 nmol/L and increment >30 nmol/L had a high negative predictive value (94, 95% CI (88–100) and 94, (88–100), respectively). Patients with a cortisol peak ≤100 nmol/L (vs >100) or an increment ≤30 nmol/L (vs >30) were less likely to have CD recurrence (odds ratios: 0.12, 95% CI (0.03–0.41) and 0.11 (0.02–0.36), respectively). Conclusion The disappearance of the response to the post-operative DT was independently associated with a lower odds of CD recurrence and offers an incremental prognostic value, which may help to stratify patients with COI and refine their follow-up according to the risk of recurrence.
Advanced glycation end-products play a role in diabetic vascular complications. Their optical properties allow to estimate their accumulation in tissues by measuring the skin autofluorescence (SAF). ...We searched for an association between SAF and major adverse cardiovascular events (MACE) incidence in subjects with Type 1 Diabetes (T1D) during a 7 year follow-up.
During year 2009, 232 subjects with T1D were included. SAF measurement, clinical age, sex, body mass index (BMI), comorbidities and biological data (HbA1C, blood lipids, renal parameters) were recorded. MACE (myocardial infarction, stroke, lower extremity amputation or a revascularization procedure) were registered at visits in the center or by phone call to general practitioners until 2016.
The participants were mainly men (59.5%), 51.5 ± 16.7 years old, with BMI 25.0 ± 4.1 kg/m
, diabetes duration 21.5 ± 13.6 years, HbA1C 7.6 ± 1.1%. LDL cholesterol was 1.04 ± 0.29 g/L, estimated Glomerular Filtration Rates (CKD-EPI): 86.3 ± 26.6 ml/min/1.73 m
. Among these subjects, 25.1% were smokers, 45.3% had arterial hypertension, 15.9% had elevated AER (≥ 30 mg/24 h), and 9.9% subjects had a history of previous MACE. From 2009 to 2016, 22 patients had at least one new MACE: 6 myocardial infarctions, 1 lower limb amputation, 15 revascularization procedures. Their SAF was 2.63 ± 0.73 arbitrary units (AU) vs 2.08 ± 0.54 for other patients (p = 0.002). Using Cox-model, after adjustment for age (as the scale time), sex, diabetes duration, BMI, hypertension, smoking status, albumin excretion rates, statin treatment and a previous history of MACE, higher baseline levels of SAF were significantly associated with an increased risk of MACE during follow-up (HR = 4.13 1.30-13.07; p = 0.02 for 1 AU of SAF) and Kaplan-Meier curve follow-up showed significantly more frequent MACE in group with SAF upper the median (p = 0.001).
A high SAF predicts MACE in patients with T1D.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The displacement of a fluid by a second immiscible fluid is a fundamental process which is relevant for many technological applications, particularly in the petroleum industry. Water is the fluid ...widely used to push oil to production wells. During this immiscible displacement, a viscous fingering instability appears at the water-oil interface. This undesirable phenomenon leads to a low oil sweeping efficiency. To prevent this situation, techniques called EOR (Enhance Oil Recovery) are used. These methods have technical, economic and environmental disadvantages. Therefore, the objective of this work is to seek a rational use of EOR techniques by determining the right place and the appropriate time to operate them. In many previous studies, the effects of viscosity ratio, interfacial tension and flow rate are investigated. In this study, we numerically investigate the effect of the heterogeneity of the medium and the presence of the fracture on this phenomenon. Three different configurations are studied. The obtained results allowed to locate the regions where the behaviour of the instability varies during displacement in the porous medium, regions where instability is increasing and others where it remains constant. a qualitative comparison between the different cases is also made.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
This study evaluates the growth dynamics and the effect of altitude on different growth phases of pre-weaned Ouled Djellal lambs in northeastern Algeria. Forty-nine lambs born in the spring to ...multiparous ewes were weighed, and their average daily gain was calculated at different ages (at birth, D 30, 60, 90 and 120). The results show that maximum growth occurs during the lamb’s first month of life at 200 g/day. Highly positive and significant correlations were recorded between D 90 and D 120 (0.94), D 60 and D 120 (0.88), D 60 and D 90 (0.87) and D 30 and D 90 (0.77). Concerning the altitude effect, lambs born in low altitude regions show a better growth performance than lambs born in high altitude regions, with a significant difference (P0.05) noticed for D 90 and D 120, which confirms that the Ouled Djellal breed is a typical breed of the steppe and the high plains.
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